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Sample records for bony heterogeneity effects

  1. Heterogeneous Economic Integration Agreement Effects

    OpenAIRE

    Scott L. Baier; Jeffrey H. Bergstrand; Clance, Matthew W.

    2015-01-01

    Gravity equations have been used for more than 50 years to estimate ex post the partial effects of trade costs on international trade flows, and the well-known - and traditionally presumed exogenous – “trade-cost elasticity” plays a central role in computing general equilibrium trade-flow and welfare effects of trade-cost changes. This paper addresses theoretically and empirically the influence of variable and fixed export costs in explaining the likely heterogeneity in the trade-cost elastic...

  2. Laboratory effect of Boni Protect containing Aureobasidium pullulans (de Bary Arnoud in the control of some fungal diseases of apple fruit

    Directory of Open Access Journals (Sweden)

    Anna Wagner

    2013-04-01

    Full Text Available The efficacy of Aureobasidium pullulans (in the biopreparation Boni Protect against different pathogens of apples (Botrytis cinerea, Monilinia fructigena, Penicillium expansum, and Pezicula malicorticis was evaluated under laboratory con- ditions. The biocontrol product was applied at concentrations of 0.05%, 0.1%, and 0.5%. Fruits of apple cultivars 'Jonagold Decosta' and 'Pinova' were used. Boni Protect was very effective against B. cinerea on cv. 'Jonagold Decosta', reducing disease incidence by 55–83.8%. On 'Pinova' apples, this biological control product was the most efficient at earlier stages of the experiment. It inhibited grey mold by 65% after 5 days from inoculation and only by 14% after 20 days. On cv. 'Jonagold Decosta', Boni Protect at a concentration of 0.1% was also effective against M. fructigena, reducing brown rot by 31.4–74.5%, but its efficiency on cv. 'Pinova' was not significant. Blue mold caused by P. expansum was inhibited only slightly by the biocontrol product, while P. malicorticis proved to be the most resistant to its antagonistic abilities.

  3. Distribution of internal pressure around bony prominences: implications to deep tissue injury and effectiveness of intermittent electrical stimulation.

    Science.gov (United States)

    Solis, Leandro R; Liggins, Adrian; Uwiera, Richard R E; Poppe, Niek; Pehowich, Enid; Seres, Peter; Thompson, Richard B; Mushahwar, Vivian K

    2012-08-01

    The overall goal of this project is to develop interventions for the prevention of deep tissue injury (DTI), a form of pressure ulcers that originates in deep tissue around bony prominences. The present study focused on: (1) obtaining detailed measures of the distribution of pressure experienced by tissue around the ischial tuberosities, and (2) investigating the effectiveness of intermittent electrical stimulation (IES), a novel strategy for the prevention of DTI, in alleviating pressure in regions at risk of breakdown due to sustained loading. The experiments were conducted in adult pigs. Five animals had intact spinal cords and healthy muscles and one had a spinal cord injury that led to substantial muscle atrophy at the time of the experiment. A force-controlled servomotor was used to load the region of the buttocks to levels corresponding to 25%, 50% or 75% of each animal's body weight. A pressure transducer embedded in a catheter was advanced into the tissue to measure pressure along a three dimensional grid around the ischial tuberosity of one hind leg. For all levels of external loading in intact animals, average peak internal pressure was 2.01 ± 0.08 times larger than the maximal interfacial pressure measured at the level of the skin. In the animal with spinal cord injury, similar absolute values of internal pressure as that in intact animals were recorded, but the substantial muscle atrophy produced larger maximal interfacial pressures. Average peak internal pressure in this animal was 1.43 ± 0.055 times larger than the maximal interfacial pressure. Peak internal pressure was localized within a ±2 cm region medio-laterally and dorso-ventrally from the bone in intact animals and ±1 cm in the animal with spinal cord injury. IES significantly redistributed internal pressure, shifting the peak values away from the bone in spinally intact and injured animals. These findings provide critical information regarding the relationship between internal and

  4. Bony regeneration effect of electron-beam irradiated hydroxyapatite and tricalcium phosphate mixtures with 7 to 3 ratio in the caravel defect model of rat

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Soung Min; Eo, Mi Young; Kang, Ji Young; Myoung, Hoon; Lee, Jong Ho [Seoul National Univ., Seoul (Korea, Republic of); Cho, Hye Jin [Korea Basic Science Institute, Daejeon (Korea, Republic of); Yea, Kwon Hae; Lee, Byung Cheol [Korea Atomic Research Institute, Daejeon (Korea, Republic of)

    2011-07-01

    The aim of this study is to evaluate the effect and potential of electron beam irradiation treatment to the new bone formation in the rat calvarial bony defects by using of 7 to 3 ratios of hydroxyapatite and tricalcium phosphate mixed with type I collagen. We used 1.0 MeV linear accelerator and 2.0 MeV superconductive linear accelerator with different irradiation dose, such as 1, 30, 60 kGy. And 10.0 MeV high frequency superconductive linear accelerator was also used. In six different experimental groups, the defect of every three rate was filled with E-beam irradiated bony mixtures, which different energy and dose, and that of rats without E-beam irradiated bony mixtures can be compared with out previous results. The other three rats were used as sham group. Rats were sacrificed after 4, 8, and 16 weeks, and grafted healing specimens were studied by clinical and radiographic findings, histomorphologic staining with hematoxylin and eosin. The large particular size of HLA was changed to small particles after E-beam irradiation, to which small particle of TEPC was engaged to small sexed HLA with organic collagen components in Seam findings. Abundant endothelial cells with preciosity were found around inner portions of grafted healing bone and many couplings of osteoblast with osteoclast in Tem findings were found in every experimental groups.

  5. Effect of decompression surgery on neurological recovery after cervical cord injury with canal stenosis but without distinct bony damage. Multicenter prospective randomized clinical trial

    International Nuclear Information System (INIS)

    A prospective randomized clinical trial examining the effects of decompression surgery on neurological recovery in patients with cervical cord injuries without remarkable bony damages was performed at 11 hospitals nationwide in Japan. Cases admitted within 14 days of injury, with a Frankel B or C classification, and with ≥20% compression of the spinal cord at the injured level, as seen on MRI, were enrolled. Decompression surgery was selected for cases in which the day of injury was an odd number, while conservative treatment was selected for all other cases. The Frankel classification and ASIA motor scores were followed for one year after injury. No statistically significant differences in neurological recovery were observed between the surgery group and the conservative treatment group. (author)

  6. Post Pelvic Radiotherapy Bony Changes

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Seung Jae [Samsung Medical Center, Seoul (Korea, Republic of)

    2009-03-15

    There has been recent interest in radiation-induced bone injury in clinical conditions, especially for pelvic insufficiency fracture (PIF). A PIF is caused by the effect of normal or physiological stress on bone with demineralization and decreased elastic resistance. Pelvic radiotherapy (RT) can also contribute to the development of a PIF. A PIF has been regarded as a rare complication with the use of megavoltage equipment. However, recent studies have reported the incidence of PIFs as 8.2{approx}20% after pelvic RT in gynecological patients, an incidence that was higher than previously believed. The importance of understanding a PIF lies in the potential for misdiagnosis as a bony metastasis. If patients complain of pelvic pain after whole-pelvis radiation therapy, the presence of a PIF must be considered in the differential diagnosis. The use of multibeam arrangements and conformal RT to reduce the volume and dose of irradiated pelvic bone can be helpful to minimize the risk of fracture. In addition to a PIF, osteonecrosis and avascular necrosis of the femoral head can develop after radiation therapy. Osteoradionecrosis of the pelvic bone is a clinical diagnostic challenge that must be differentiated from an osseous metastasis. A post-radiation bone sarcoma can result as a long-term sequela of pelvic irradiation for uterine cervical cancer.

  7. Histologic and histomorphometric evaluation of the effect of lactoferrin combined with anorganic bovine bone on healing of experimentally induced bony defects on rabbit calvaria

    Directory of Open Access Journals (Sweden)

    Mojgan Paknejad

    2012-01-01

    Conclusion: Based on results of this study, the combination of lactoferrin and ABB did not show any significant improvement in bone regeneration compared with ABB alone in surgically induced bony defects in rabbit calvaria.

  8. Heterogeneous Causal Effects and Sample Selection Bias

    DEFF Research Database (Denmark)

    Breen, Richard; Choi, Seongsoo; Holm, Anders

    2015-01-01

    The role of education in the process of socioeconomic attainment is a topic of long standing interest to sociologists and economists. Recently there has been growing interest not only in estimating the average causal effect of education on outcomes such as earnings, but also in estimating how...... causal effects might vary over individuals or groups. In this paper we point out one of the under-appreciated hazards of seeking to estimate heterogeneous causal effects: conventional selection bias (that is, selection on baseline differences) can easily be mistaken for heterogeneity of causal effects...

  9. Primitive Form of Bony Fish Unveiled

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ With over 50,000 species,Osteichthyans, or bony fish, accounts for 98% of the present-day vertebrates. Bony fish falls into two groups: actinopterygians, meaning ray-finned bony fish, and sarcopterygians,meaning lobe-finned bony fish. The huge morphotype difference of the two catagories cast doubts on research into the origin and evolution of bony fish. The recent discovery of a primitive fish species by CAS researchers and their overseas colleagues provides a missing link between the two lineages, unveiling unique features for understanding primitive bony vertebrates.

  10. Arthroscopic Bony Bankart Repair Using Double-Threaded Headless Screw: A Case Report

    Directory of Open Access Journals (Sweden)

    Takeshi Kokubu

    2012-01-01

    Full Text Available We present a case of arthroscopic fixation for bony Bankart lesion using a double-threaded cannulated screw. A 39-year-old man sustained a left shoulder injury from a motorcycle accident. Radiographs showed bony Bankart lesion and CT revealed 40% defect of glenoid articular surface. Arthroscopic fixation was performed using double-threaded cannulated screw after the bony fragment was reduced by suturing the labrum at the edge with a suture anchor. Arthroscopic bony Bankart repair using double-threaded cannulated screw fixation is effective because compression force could be applied between bony fragments and the screw head is not exposed in the glenohumeral joint.

  11. Biochemical effect of a histidine phosphatase acid (phytase) of Aspergillus japonicus var. Saito on performance and bony characteristics of broiler.

    Science.gov (United States)

    Maller, Alexandre; de Quadros, Thays Cristina Oliveira; Junqueira, Otto M; Graña, Alfredo Lora; de Lima Montaldi, Ana Paula; Alarcon, Ricardo Fernandes; Jorge, João Atílio; de Lourdes T M Polizeli, Maria

    2016-01-01

    Phytases are enzymes that hydrolyze the ester linkage of phytic acid, releasing inositol and inorganic phosphate. The phytic acid (phytate) is a major form of phosphorus in plant foods. Knowing that diet for animal of production has the cereal base (corn and soybean), primarily, broilers need for an alternative to use of the phosphate present in these ingredients, since it does not naturally produce the enzyme phytase, which makes it available. The aims of this work was studding the safe supplementation of Aspergillus japonicus var. Saito crude phytase in feeding broilers and check the biochemical effect on performance and bones of these animals. The enzymatic extract did not have aflatoxins B1, B2, G2 and G1 and zearalenone and ochratoxin, and low concentrations of this extract did not have cytotoxic effects on cells derived from lung tissue. The in vivo experiments showed that the phytase supplied the available phosphate reduction in the broiler feed formulation, with a live weight, weight gain, feed intake, feed conversion, viability, productive efficiency index and carcass yield similar to the control test. Furthermore, the phytase supplementation favored the formation of bone structure and performance of the broilers. The results show the high biotechnological potential of A. japonicus phytase on broiler food supplementation to reduce phosphorus addition in the food formulation. So, this enzyme could be used as a commercial alternative to animal diet supplementation. PMID:27625972

  12. Seismoelectric effects due to mesoscopic heterogeneities

    CERN Document Server

    Jougnot, D; Carbajal, M Rosas; Linde, N; Holliger, K

    2014-01-01

    While the seismic effects of wave-induced fluid flow due to mesoscopic heterogeneities have been studied for several decades, the role played by these types of heterogeneities on seismoelectric phenomena is largely unexplored. To address this issue, we have developed a novel methodological framework which allows for the coupling of wave-induced fluid flow, as inferred through numerical oscillatory compressibility tests, with the pertinent seismoelectric conversion mechanisms. Simulating the corresponding response of a water-saturated sandstone sample containing mesoscopic fractures, we demonstrate for the first time that these kinds of heterogeneities can produce measurable seismoelectric signals under typical laboratory conditions. Given that this phenomenon is sensitive to key hydraulic and mechanical properties, we expect that the results of this pilot study will stimulate further exploration on this topic in several domains of the Earth, environmental, and engineering sciences.

  13. On the compensation effect in heterogeneous catalysis

    DEFF Research Database (Denmark)

    Pedersen, Thomas Bligaard; Honkala, Johanna Karoliina; Logadottir, Ashildur;

    2003-01-01

    to illustrate the effect. Both experiments and a detailed kinetic model show a compensation effect. Second, we use density functional theory calculations to show that the compensation effect is not only due to changes in the activation barrier and prefactor of the rate-determining step, N-2 dissociation. We......For a class of heterogeneously catalyzed reactions, we explain the compensation effect in terms of a switching of kinetic regimes leading to a concomitant change in the apparent activation energy and in the prefactor for the overall rate of the reaction. We first use the ammonia synthesis...

  14. Bony sequestrum: A radiologic review

    Energy Technology Data Exchange (ETDEWEB)

    Jennin, Felicie; Bousson, Valerie; Parlier, Caroline; Jomaah, Nabil; Khanine, Vanessa; Laredo, Jean-Denis [Lariboisiere Hospital, Department of Radiology, Paris (France)

    2011-08-15

    According to a pathological definition, a bony sequestrum is defined as a piece of devitalized bone that has been separated from the surrounding bone during the process of necrosis. However, the radiological definition of a sequestrum is different and refers to an image of calcification visible within a lucent lesion, completely separated from the surrounding bone, without referring to the vascular status and histological nature of the calcified tissue. The term ''button sequestrum'' has been used in calvarial lesions. The prototype conditions that may present with a bony sequestrum are osteomyelitis and skeletal tuberculosis. Other conditions such as radiation necrosis, eosinophilic granuloma, metastatic carcinoma, primary lymphoma of bone, aggressive fibrous tumors may also manifest as osteolytic lesions containing a sequestrum. In addition, some primary bone tumors produce a matrix that may mineralize and sometimes simulate a bone sequestrum. These include osteoid tumors (osteoid osteoma, osteoblastoma), cartilaginous tumors (chondroma and chondroblastoma), lipomatous tumors (lipoma), and benign fibrous tumors (fibromyxoma, myxoma, and desmoplastic fibroma). Therefore, various conditions may present at imaging as a small area of osteolysis containing central calcifications. However, a careful analysis of the sequestrum as well as the associated clinical and radiological findings often enables to point toward a limited number of conditions. (orig.)

  15. Bony sequestrum: A radiologic review

    International Nuclear Information System (INIS)

    According to a pathological definition, a bony sequestrum is defined as a piece of devitalized bone that has been separated from the surrounding bone during the process of necrosis. However, the radiological definition of a sequestrum is different and refers to an image of calcification visible within a lucent lesion, completely separated from the surrounding bone, without referring to the vascular status and histological nature of the calcified tissue. The term ''button sequestrum'' has been used in calvarial lesions. The prototype conditions that may present with a bony sequestrum are osteomyelitis and skeletal tuberculosis. Other conditions such as radiation necrosis, eosinophilic granuloma, metastatic carcinoma, primary lymphoma of bone, aggressive fibrous tumors may also manifest as osteolytic lesions containing a sequestrum. In addition, some primary bone tumors produce a matrix that may mineralize and sometimes simulate a bone sequestrum. These include osteoid tumors (osteoid osteoma, osteoblastoma), cartilaginous tumors (chondroma and chondroblastoma), lipomatous tumors (lipoma), and benign fibrous tumors (fibromyxoma, myxoma, and desmoplastic fibroma). Therefore, various conditions may present at imaging as a small area of osteolysis containing central calcifications. However, a careful analysis of the sequestrum as well as the associated clinical and radiological findings often enables to point toward a limited number of conditions. (orig.)

  16. Injury of anterior cruciate ligament with associated bony lesions: MR image

    International Nuclear Information System (INIS)

    To evaluate the characteristic MR findings in injury of the anterior cruciate ligament (ACL) with associated bony lesions. We reviewed MR findings and the corresponding arthroscopic or operative results of 48 patients with ACL injuries, and evaluated ACL signal intensity and contour. In associated bony lesions, we determined the location of avulsion fracture and bony bruise. Complete ACL tears were seen in 27 cases, partial tears in 13, and avulsion injury in eight. Complete tears showed heterogeneously increased signal intensity with contour bulging in ten cases (37%), and combined bony lesion in 14 (52%). ACL with a thin continous low signal intensity band surrounding heterogeneously-increased signal intensity suggested partial tears, and was seen in three of 13 proven cases (23%) of partial ACL tears;combined bony lesion was seen in four such cases(31%). There were eight cases of avulsion fracture;the most frequent site was the anterolateral portion of the tibial spine (n=6). The most frequent sites of bony lesion were at the midportion of the lateral femoral condyle (n=6), and the posterior portion of the lateral tibial plateau (n=6);the next most frequent site was the anterior portion of the lateral tibial plateau (n=5). Tearing of the ACL was seen on MRI as ligament discontinuity, and heterogeneously increased signal intensity with ACL contour bulging. The most frequent sites of associated bony lesions were the midportion of the lateral femoral condyle, and the posterior portion of the lateral tibial plateau. In associated bony lesions, bony contusion suggested ACL tearing, but avulsion fracture suggested ligament avulsion injury without tear

  17. Injury of anterior cruciate ligament with associated bony lesions: MR image

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Soon; Oh, Yeon Hee; Lee, Chang Wook [Dongguk Univ. College of Medicine, Seoul (Korea, Republic of); Kim, Yong Min [Chungbuk Univ. College of Medicine, Chongju (Korea, Republic of); Lee, Hyeon Kyeong; Kim, Seung Hyeon; Lee, Sung Woo [Dongguk Univ. College of Medicine, Seoul (Korea, Republic of)

    1997-05-01

    To evaluate the characteristic MR findings in injury of the anterior cruciate ligament (ACL) with associated bony lesions. We reviewed MR findings and the corresponding arthroscopic or operative results of 48 patients with ACL injuries, and evaluated ACL signal intensity and contour. In associated bony lesions, we determined the location of avulsion fracture and bony bruise. Complete ACL tears were seen in 27 cases, partial tears in 13, and avulsion injury in eight. Complete tears showed heterogeneously increased signal intensity with contour bulging in ten cases (37%), and combined bony lesion in 14 (52%). ACL with a thin continous low signal intensity band surrounding heterogeneously-increased signal intensity suggested partial tears, and was seen in three of 13 proven cases (23%) of partial ACL tears;combined bony lesion was seen in four such cases(31%). There were eight cases of avulsion fracture;the most frequent site was the anterolateral portion of the tibial spine (n=6). The most frequent sites of bony lesion were at the midportion of the lateral femoral condyle (n=6), and the posterior portion of the lateral tibial plateau (n=6);the next most frequent site was the anterior portion of the lateral tibial plateau (n=5). Tearing of the ACL was seen on MRI as ligament discontinuity, and heterogeneously increased signal intensity with ACL contour bulging. The most frequent sites of associated bony lesions were the midportion of the lateral femoral condyle, and the posterior portion of the lateral tibial plateau. In associated bony lesions, bony contusion suggested ACL tearing, but avulsion fracture suggested ligament avulsion injury without tear.

  18. Bony ankylosis following thermal and electrical injury

    Energy Technology Data Exchange (ETDEWEB)

    Balen, P.F.; Helms, C.A. [Dept. of Radiology, Duke University Medical Center, Durham, NC (United States)

    2001-07-01

    Objective. Bony ankylosis has been described following trauma, paralysis, psoriasis, Reiter's syndrome, ankylosing spondylitis, juvenile chronic arthritis and rheumatoid arthritis. Reports of bony ankylosis following thermal and electrical injury are limited.Design and patients. Thirteen cases of burn-related joint ankylosis in four patients are presented.Conclusion. Patients with burns from thermal or electrical injury may develop bony ankylosis among other radiographic manifestations. This bony ankylosis may result either from bridging extra-articular heterotopic ossification with preservation of the underlying joint or from intra-articular fusion due to joint destruction. (orig.)

  19. Bony ankylosis following thermal and electrical injury

    International Nuclear Information System (INIS)

    Objective. Bony ankylosis has been described following trauma, paralysis, psoriasis, Reiter's syndrome, ankylosing spondylitis, juvenile chronic arthritis and rheumatoid arthritis. Reports of bony ankylosis following thermal and electrical injury are limited.Design and patients. Thirteen cases of burn-related joint ankylosis in four patients are presented.Conclusion. Patients with burns from thermal or electrical injury may develop bony ankylosis among other radiographic manifestations. This bony ankylosis may result either from bridging extra-articular heterotopic ossification with preservation of the underlying joint or from intra-articular fusion due to joint destruction. (orig.)

  20. The effect of Songmeile injectio on joint rehabilitation in patients with chronic bony arthrosis%松梅乐注射液对膝部骨性关节病关节功能康复的作用

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@Background:Songmeile injectio is a kind of bone-inducing growth factors extracted from bones of deer,which contains bone-forming protein,bone-derived growth factor,cartilage-derived growth factor,TGF,and FGP.It was involved in metabolism of calcium,phosphorus,local blood circulation, and injury repair. We observed effects of Songmeile injectio on arthritis and retrograde affection of knee. Objective: To study effect of songmeile injectio on rehabilitation of bony arthritis of knee joint. Unit:Department of Orthopedics,Second Affiliated Hospital of Hunan Traditional Chinese Medicine Cellege.

  1. Reactor core heterogeneity effects on radionuclide inventory

    International Nuclear Information System (INIS)

    Highlights: ► Reactor core heterogeneity effects on radionuclide inventory are studied. ► A methodology for inventory estimation of individual fuel assembly is developed. ► Estimated inventory using presently developed and conventional method is compared. ► Radionuclide density peak and its location in equilibrium VVER core are investigated. - Abstract: Understanding fission product behavior is an important aspect of nuclear safety studies. A nuclear reactor core contains complex mixture of fuel elements with different levels of enrichment, power and burnup. Conventional method of core radionuclide inventory estimation is based on use of homogenized core parameters like burnup, enrichment, specific power etc. This approach does not reveal the variation in radionuclide density among different fuel elements within the core. The present work aims to bridge this knowledge gap by estimating the distribution of radionuclides in the nuclear reactor core taking into account the heterogeneity of the core explicitly. The analysis has brought out peak radionuclide density in the core which can be helpful in appropriate estimation of the radiological release in the accidental scenarios involving failures of few fuel assemblies. A quantitative comparison of total core inventory estimated based conventional core average parameters and detailed core inventory using individual fuel assembly inventory estimate has been made

  2. Recursive partitioning for heterogeneous causal effects.

    Science.gov (United States)

    Athey, Susan; Imbens, Guido

    2016-07-01

    In this paper we propose methods for estimating heterogeneity in causal effects in experimental and observational studies and for conducting hypothesis tests about the magnitude of differences in treatment effects across subsets of the population. We provide a data-driven approach to partition the data into subpopulations that differ in the magnitude of their treatment effects. The approach enables the construction of valid confidence intervals for treatment effects, even with many covariates relative to the sample size, and without "sparsity" assumptions. We propose an "honest" approach to estimation, whereby one sample is used to construct the partition and another to estimate treatment effects for each subpopulation. Our approach builds on regression tree methods, modified to optimize for goodness of fit in treatment effects and to account for honest estimation. Our model selection criterion anticipates that bias will be eliminated by honest estimation and also accounts for the effect of making additional splits on the variance of treatment effect estimates within each subpopulation. We address the challenge that the "ground truth" for a causal effect is not observed for any individual unit, so that standard approaches to cross-validation must be modified. Through a simulation study, we show that for our preferred method honest estimation results in nominal coverage for 90% confidence intervals, whereas coverage ranges between 74% and 84% for nonhonest approaches. Honest estimation requires estimating the model with a smaller sample size; the cost in terms of mean squared error of treatment effects for our preferred method ranges between 7-22%. PMID:27382149

  3. Landscape Heterogeneity-Biodiversity Relationship: Effect of Range Size

    OpenAIRE

    Katayama, Naoki; Amano, Tatsuya; Naoe, Shoji; YAMAKITA Takehisa; Komatsu, Isamu; Takagawa, Shin-ichi; Sato, Naoto; Ueta, Mutsuyuki; Miyashita, Tadashi

    2014-01-01

    The importance of landscape heterogeneity to biodiversity may depend on the size of the geographic range of species, which in turn can reflect species traits (such as habitat generalization) and the effects of historical and contemporary land covers. We used nationwide bird survey data from Japan, where heterogeneous landscapes predominate, to test the hypothesis that wide-ranging species are positively associated with landscape heterogeneity in terms of species richness and abundance, wherea...

  4. Primary bony Hodgkin’s lymphoma

    OpenAIRE

    Binesh, Fariba; Mirjalili, Mohammad Reza; Akhavan, Ali; Navabii, Hossein

    2012-01-01

    Hodgkin’s lymphoma most commonly presents with progressive painless enlargement of peripheral lymph nodes, especially around the cervical region. At the time of diagnosis osseous involvement is uncommon and even in the late stages only 9–35% of cases have any bony involvement. Rarely Hodgkin’s lymphoma presents as an osseous lesion without involvement of lymph nodes, therefore the histological diagnosis of osseous Hodgkin’s lymphoma can be problematic. Here, the authors present a rare case of...

  5. Ultrasound of the elbow: A systematic approach using bony landmarks

    International Nuclear Information System (INIS)

    The use of bony landmarks can be helpful in performing an ultrasound study of the elbow. We discuss bony landmarks that can be used for evaluation of the common extensor tendon, ulnar collateral ligament and common flexor tendon, coronoid and olecranon fossa, ulnar nerve, and biceps tendon. We discuss bony landmarks for each of these structures.

  6. Effectiveness of Microinvasive Arthroscopic Therapy of Bony Ankle Impingent Symdrome%踝关节镜微创治疗踝关节前方骨性撞击的疗效分析

    Institute of Scientific and Technical Information of China (English)

    陈继铭; 钟环; 陈海聪; 冯柏淋

    2015-01-01

    目的:探讨关节镜在踝关节骨性撞击综合症中的诊治效果。方法收集18例踝关节骨性撞击综合征患者,行关节镜检查及镜下手术,其中男14例,女4例,平均年龄27.6岁(17~55岁)。14例患者有踝关节扭伤史,踝关节疼痛持续时间7~66个月,平均22.5个月。所有患者都有踝关节前方疼痛、关节活动度降低、肿胀、踝关节撞击试验阳性。关节镜下治疗包括清除骨赘、清除疤痕组织和滑膜组织,去除骨软骨碎片,修整损伤的关节软骨面。结果18例患者获5~18个月随访,平均10个月,术后踝关节功能评估根据美国足踝外科协会足踝关节评分系统(AOFAS):优10例;良6例;中2例;优良率88.9%。1例出现足背麻木,1例出现足背动脉损伤。结论踝关节镜是治疗踝关节骨性撞击综合征的有效方法。%Objective To explore the effectiveness of Microinvasive arthroscopy for bony ankle impingement syn-drome. Methods 18 patients with bony ankle impingement syndrome were treated with arthroscopy surgery. Among them, there were 14 males and 4 females with an average age of 27. 6 years(range,16~55 years). Fourteen patients had a history of obvious ankle sprains. The disease duration was 7~66 months(mean,22. 5 months). All cases had ankle pain,limitation of activity,and positive results of ankle impact test. Arthroscopic intervention included removing osteophytes,debriding fabric scars and synovial membrane tissues,and removing osteochondral fragments,mending the damage of articular cartilage surface. Results All patients were followed for 5~18(mean 10. 0) months. The efficacy was evaluated by the American Orthopedic Foot and Ankle Society ( AOFAS) . There were 10 cases in excellent,6 cases in good grade,and 2 cases in medium grade. The excellent and good rate was up to 88. 9%. Among the 18 cases,there were no complications such as postoperative infection, neurologic damage,and injury of blood vessel. One case showed foot

  7. Estimation of effective hydrogeological parameters in heterogeneous and anisotropic aquifers

    Science.gov (United States)

    Lin, Hsien-Tsung; Tan, Yih-Chi; Chen, Chu-Hui; Yu, Hwa-Lung; Wu, Shih-Ching; Ke, Kai-Yuan

    2010-07-01

    SummaryObtaining reasonable hydrological input parameters is a key challenge in groundwater modeling. Analysis of temporal evolution during pump-induced drawdown is one common approach used to estimate the effective transmissivity and storage coefficients in a heterogeneous aquifer. In this study, we propose a Modified Tabu search Method (MTM), an improvement drawn from an alliance between the Tabu Search (TS) and the Adjoint State Method (ASM) developed by Tan et al. (2008). The latter is employed to estimate effective parameters for anisotropic, heterogeneous aquifers. MTM is validated by several numerical pumping tests. Comparisons are made to other well-known techniques, such as the type-curve method (TCM) and the straight-line method (SLM), to provide insight into the challenge of determining the most effective parameter for an anisotropic, heterogeneous aquifer. The results reveal that MTM can efficiently obtain the best representative and effective aquifer parameters in terms of the least mean square errors of the drawdown estimations. The use of MTM may involve less artificial errors than occur with TCM and SLM, and lead to better solutions. Therefore, effective transmissivity is more likely to be comprised of the geometric mean of all transmissivities within the cone of depression based on a precise estimation of MTM. Further investigation into the applicability of MTM shows that a higher level of heterogeneity in an aquifer can induce an uncertainty in estimations, while the changes in correlation length will affect the accuracy of MTM only once the degree of heterogeneity has also risen.

  8. Local heterogeneity effects on small-sample worths

    International Nuclear Information System (INIS)

    One of the parameters usually measured in a fast reactor critical assembly is the reactivity associated with inserting a small sample of a material into the core (sample worth). Local heterogeneities introduced by the worth measurement techniques can have a significant effect on the sample worth. Unfortunately, the capability is lacking to model some of the heterogeneity effects associated with the experimental technique traditionally used at ANL (the radial tube technique). It has been suggested that these effects could account for a large portion of what remains of the longstanding central worth discrepancy. The purpose of this paper is to describe a large body of experimental data - most of which has never been reported - that shows the effect of radial tube-related local heterogeneities

  9. Effects of Heterogeneous Diffuse Fibrosis on Arrhythmia Dynamics and Mechanism.

    Science.gov (United States)

    Kazbanov, Ivan V; ten Tusscher, Kirsten H W J; Panfilov, Alexander V

    2016-01-01

    Myocardial fibrosis is an important risk factor for cardiac arrhythmias. Previous experimental and numerical studies have shown that the texture and spatial distribution of fibrosis may play an important role in arrhythmia onset. Here, we investigate how spatial heterogeneity of fibrosis affects arrhythmia onset using numerical methods. We generate various tissue textures that differ by the mean amount of fibrosis, the degree of heterogeneity and the characteristic size of heterogeneity. We study the onset of arrhythmias using a burst pacing protocol. We confirm that spatial heterogeneity of fibrosis increases the probability of arrhythmia induction. This effect is more pronounced with the increase of both the spatial size and the degree of heterogeneity. The induced arrhythmias have a regular structure with the period being mostly determined by the maximal local fibrosis level. We perform ablations of the induced fibrillatory patterns to classify their type. We show that in fibrotic tissue fibrillation is usually of the mother rotor type but becomes of the multiple wavelet type with increase in tissue size. Overall, we conclude that the most important factor determining the formation and dynamics of arrhythmia in heterogeneous fibrotic tissue is the value of maximal local fibrosis. PMID:26861111

  10. Effect of heterogeneities on evaluating earthquake triggering of volcanic eruptions

    Directory of Open Access Journals (Sweden)

    J. Takekawa

    2013-02-01

    Full Text Available Recent researches have indicated coupling between volcanic eruptions and earthquakes. Some of them calculated static stress transfer in subsurface induced by the occurrences of earthquakes. Most of their analyses ignored the spatial heterogeneity in subsurface, or only took into account the rigidity layering in the crust. On the other hand, a smaller scale heterogeneity of around hundreds of meters has been suggested by geophysical investigations. It is difficult to reflect that kind of heterogeneity in analysis models because accurate distributions of fluctuation are not well understood in many cases. Thus, the effect of the ignorance of the smaller scale heterogeneity on evaluating the earthquake triggering of volcanic eruptions is also not well understood. In the present study, we investigate the influence of the assumption of homogeneity on evaluating earthquake triggering of volcanic eruptions using finite element simulations. The crust is treated as a stochastic media with different heterogeneous parameters (correlation length and magnitude of velocity perturbation in our simulations. We adopt exponential and von Karman functions as spatial auto-correlation functions (ACF. In all our simulation results, the ignorance of the smaller scale heterogeneity leads to underestimation of the failure pressure around a chamber wall, which relates to dyke initiation. The magnitude of the velocity perturbation has a larger effect on the tensile failure at the chamber wall than the difference of the ACF and the correlation length. The maximum effect on the failure pressure in all our simulations is about twice larger than that in the homogeneous case. This indicates that the estimation of the earthquake triggering due to static stress transfer should take account of the heterogeneity of around hundreds of meters.

  11. Effect of tissue heterogeneity on quantification in positron emission tomography

    International Nuclear Information System (INIS)

    As a result of the limited spatial resolution of positron emission tomographic scanners, the measurements of physiological parameters are compromised by tissue heterogeneity. The effect of tissue heterogeneity on a number of parameters was studied by simulation and an analytical method. Five common tracer models were assessed. The input and tissue response functions were assumed to be free from noise and systematic errors. The kinetic model was assumed to be perfect. Two components with different kinetics were mixed in different proportions and contrast with respect to the model parameters. Different experimental protocols were investigated. Of three methods investigated for the measurement of cerebral blood flow (CBF) (steady state, dynamic, integral), the second one was least sensitive to errors caused by tissue heterogeneity and the main effect was an underestimation of the distribution volume. With the steady state method, errors in oxygen extraction fraction caused by tissue heterogeneity were always found to be less than the corresponding errors in CBF. For myocardial blood flow the steady state method was found to perform better than the bolus method. The net accumulation of substrate (i.e. rCMRglc in the case of glucose analogs) was found to be comparatively insensitive to tissue heterogeneity. Individual rate constans such as k2 and k3 for efflux and metabolism of the substrate in the pool of unmetabolized substrate in the tissue, respectively, were found to be more sensitive. In studies of radioligand binding, using only tracer doses, the effect of tissue heterogeneity on the parameter kon.Bmax could be considerable. In studies of radioligand binding using a protocol with two experiments, one with high and one with low specific activity, Bmax was found to be insensitive while Kd was very sensitive to tissue heterogeneity. (orig.)

  12. Effect of tissue heterogeneity on quantification in positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Blomqvist, G. [Dept. of Clinical Neuroscience, Experimental Alcohol and Drug Addiction Research Section, Karolinska Hospital, Stockholm (Sweden); Lammertsma, A.A. [PET Methodology Group, Cyclotron Unit, MRC Clinical Sciences Centre, Royal Postgraduate Medical School, Hammersmith Hospital, London (United Kingdom); Mazoyer, B. [Service Hospitalier Frederic Joliot CEA/Dept. de Biologie, Hopital d`Orsay and Antenne d`Informatique Medicale, Hopital Robert Debre, Paris (France); Wienhard, K. [Max-Planck-Inst. fuer Neurologische Forschung, Koeln (Germany)

    1995-07-01

    As a result of the limited spatial resolution of positron emission tomographic scanners, the measurements of physiological parameters are compromised by tissue heterogeneity. The effect of tissue heterogeneity on a number of parameters was studied by simulation and an analytical method. Five common tracer models were assessed. The input and tissue response functions were assumed to be free from noise and systematic errors. The kinetic model was assumed to be perfect. Two components with different kinetics were mixed in different proportions and contrast with respect to the model parameters. Different experimental protocols were investigated. Of three methods investigated for the measurement of cerebral blood flow (CBF) (steady state, dynamic, integral), the second one was least sensitive to errors caused by tissue heterogeneity and the main effect was an underestimation of the distribution volume. With the steady state method, errors in oxygen extraction fraction caused by tissue heterogeneity were always found to be less than the corresponding errors in CBF. For myocardial blood flow the steady state method was found to perform better than the bolus method. The net accumulation of substrate (i.e. rCMR{sub glc} in the case of glucose analogs) was found to be comparatively insensitive to tissue heterogeneity. Individual rate constans such as k{sub 2} and k{sub 3} for efflux and metabolism of the substrate in the pool of unmetabolized substrate in the tissue, respectively, were found to be more sensitive. In studies of radioligand binding, using only tracer doses, the effect of tissue heterogeneity on the parameter k{sub on}.B{sub max} could be considerable. In studies of radioligand binding using a protocol with two experiments, one with high and one with low specific activity, B{sub max} was found to be insensitive while K{sub d} was very sensitive to tissue heterogeneity. (orig.)

  13. Effects of Heterogeneous Sink Distribution on Void Swelling

    DEFF Research Database (Denmark)

    Leffers, Torben; Volobuyev, A. V.; Gann, V. V.;

    1986-01-01

    different shells by a finite-difference method. From these concentrations the local and the average swelling rate and the dependence of this effect of the heterogeneities in sink distribution on swelling rate and the dependence of this effect on various structural parameters are investigated....

  14. The heterogeneous effects of HIV testing

    OpenAIRE

    Baird, Sarah; Gong, Erick; McIntosh, Craig; Özler, Berk

    2014-01-01

    An extensive multi-disciplinary literature examines the effects of learning one's HIV status on subsequent risky sexual behaviors. However, many of these studies rely on non-experimental designs; use self-reported outcome measures, or both. This study investigates the effects of a randomly assigned home based HIV testing and counseling (HTC) intervention on risky sexual behaviors and schoo...

  15. Competing risk and heterogeneity of treatment effect in clinical trials

    Directory of Open Access Journals (Sweden)

    Alsheikh-Ali Alawi

    2008-05-01

    Full Text Available Abstract It has been demonstrated that patients enrolled in clinical trials frequently have a large degree of variation in their baseline risk for the outcome of interest. Thus, some have suggested that clinical trial results should routinely be stratified by outcome risk using risk models, since the summary results may otherwise be misleading. However, variation in competing risk is another dimension of risk heterogeneity that may also underlie treatment effect heterogeneity. Understanding the effects of competing risk heterogeneity may be especially important for pragmatic comparative effectiveness trials, which seek to include traditionally excluded patients, such as the elderly or complex patients with multiple comorbidities. Indeed, the observed effect of an intervention is dependent on the ratio of outcome risk to competing risk, and these risks – which may or may not be correlated – may vary considerably in patients enrolled in a trial. Further, the effects of competing risk on treatment effect heterogeneity can be amplified by even a small degree of treatment related harm. Stratification of trial results along both the competing and the outcome risk dimensions may be necessary if pragmatic comparative effectiveness trials are to provide the clinically useful information their advocates intend.

  16. Treatment Effect Heterogeneity in Theory and Practice

    OpenAIRE

    Angrist, Joshua D.

    2003-01-01

    Instrumental Variables (IV) methods identify internally valid causal effects for individuals whose treatment status is manipulable by the instrument at hand. Inference for other populations requires some sort of homogeneity assumption. This paper outlines a theoretical framework that nests all possible homogeneity assumptions for a causal treatment-effects model with a binary instrument. The framework suggests strategies for using IV estimates for extrapolation, while making it clear that eff...

  17. Heterogeneous Causal Effects and Sample Selection Bias

    DEFF Research Database (Denmark)

    Breen, Richard; Choi, Seongsoo; Holm, Anders

    2015-01-01

    The role of education in the process of socioeconomic attainment is a topic of long standing interest to sociologists and economists. Recently there has been growing interest not only in estimating the average causal effect of education on outcomes such as earnings, but also in estimating how cau...

  18. Heterogeneous structure effect on molten salt blanket neutronics

    Energy Technology Data Exchange (ETDEWEB)

    Grebyonkin, K.F.; Kandiev, Ya.Z.; Malyshkin, G.N.; Orlov, A.I. [Inst. of Technical Pysics, Chelyabinsk (Russian Federation). Dept. of Physics

    1997-09-01

    The report presents the results of the molten salt blanket neutronics calculations performed for researchers of a facility for accelerator-driven transmutation of long-lived radioactive wastes and plutonium conversion. Heterogeneous structure effect on molten salt blanket neutronics was studied through computation. 4 refs., 1 fig., 1 tab.

  19. Modeling Strain Rate Effect for Heterogeneous Brittle Materials

    Institute of Scientific and Technical Information of China (English)

    MA Guowei; DONG Aiai; LI Jianchun

    2006-01-01

    Rocks are heterogeneous from the point of microstructure which is of significance to their dynamic failure behavior.Both the compressive and tensile strength of rock-like materials is regarded different from the static strength.The present study adopts smoothed particle hydrodynamics (SPH) which is a virtual particle based meshfree method to investigate strain rate effect for heterogeneous brittle materials.The SPH method is capable of simulating rock fracture,free of the mesh constraint of the traditional FEM and FDM models.A pressure dependent J-H constitutive model involving heterogeneity is employed in the numerical modeling.The results show the compressive strength increases with the increase of strain rate as well as the tensile strength,which is important to the engineering design.

  20. Effect of Heterogeneity in Initial Geographic Distribution on Opinions’ Competitiveness

    Directory of Open Access Journals (Sweden)

    Alexander S. Balankin

    2015-05-01

    Full Text Available Spin dynamics on networks allows us to understand how a global consensus emerges out of individual opinions. Here, we are interested in the effect of heterogeneity in the initial geographic distribution of a competing opinion on the competitiveness of its own opinion. Accordingly, in this work, we studied the effect of spatial heterogeneity on the majority rule dynamics using a three-state spin model, in which one state is neutral. Monte Carlo simulations were performed on square lattices divided into square blocks (cells. Accordingly, one competing opinion was distributed uniformly among cells, whereas the spatial distribution of the rival opinion was varied from the uniform to heterogeneous, with the median-to-mean ratio in the range from 1 to 0. When the size of discussion group is odd, the uncommitted agents disappear completely after  3.30 ± 0.05 update cycles, and then the system evolves in a two-state regime with complementary spatial distributions of two competing opinions. Even so, the initial heterogeneity in the spatial distribution of one of the competing opinions causes a decrease of this opinion competitiveness. That is, the opinion with initially heterogeneous spatial distribution has less probability to win, than the opinion with the initially uniform spatial distribution, even when the initial concentrations of both opinions are equal. We found that although the time to consensus , the opinion’s recession rate is determined during the first 3.3 update cycles. On the other hand, we found that the initial heterogeneity of the opinion spatial distribution assists the formation of quasi-stable regions, in which this opinion is dominant. The results of Monte Carlo simulations are discussed with regard to the electoral competition of political parties.

  1. Cavernous Hemangioma of the Bony Orbit

    Institute of Scientific and Technical Information of China (English)

    Jianhua Yan; Yu Cai; Zhongyao Wu; Ji Han; Youjian Pang

    2005-01-01

    Purpose: To study the clinical features, diagnosis and management of intraosseous cavernous hemangioma of the orbit.Methods: Five cases of intraosseous cavernous hemangioma seen in our hospital from Jan 1, 1986 to Dec 31, 2000 were reviewed.Results: Among all five cases, two were male and three were female. The mean age was 47.6 years old, ranging from 39.0 to 55.0 years. The left orbit was affected in 4 cases and the right one in 1 case. The bony involvement occurred in frontal bone (two cases),zygomatic bone (two cases) and sphenoid bone (one case). A painless, slowly enlarging hard bony mass fixed to the bone with no pulsations was the main clinical sign. The x-ray and CT appearance of intraosseous cavernous hemangioma of the orbit were characteristic and usually diagnostic. The differential diagnosis of it included fibrous dysplasia,eosinophilic granuloma, multiple myeloma and metastatic carcinoma. Treatment is local removal of the bone containing the tumor.Conclusions: Intraosseous cavernous hemangioma is a rare tumor of the orbit and usually has good surgical result.

  2. Effect of Heterogeneity of JSFR Fuel Assemblies to Power Distribution

    International Nuclear Information System (INIS)

    The Japanese sodium-cooled fast reactor JSFR is an oxide fueled system rated at 1,500 MWe. The core is composed of large fuel assemblies with an inner duct for each assembly. Thus, the assembly heterogeneity is rather strong. The purpose of the present paper is to make clear the effect of the heterogeneity to assembly and core characteristics, especially to power distribution. The inner duct is located at one corner of a hexagonal assembly, and the effect of the location has been investigated. We have compared the power distribution when the inner duct is always located near the core center and/or far from the core center. The power at the core center increased and decreased by ~10%, respectively compared to the case when the inner duct is randomly located. Thus, the location has important effect to power distribution. (author)

  3. TRAPEZE: a randomised controlled trial of the clinical effectiveness and cost-effectiveness of chemotherapy with zoledronic acid, strontium-89, or both, in men with bony metastatic castration-refractory prostate cancer.

    Science.gov (United States)

    James, Nicholas; Pirrie, Sarah; Pope, Ann; Barton, Darren; Andronis, Lazaros; Goranitis, Ilias; Collins, Stuart; McLaren, Duncan; O'Sullivan, Joe; Parker, Chris; Porfiri, Emilio; Staffurth, John; Stanley, Andrew; Wylie, James; Beesley, Sharon; Birtle, Alison; Brown, Janet; Chakraborti, Prabir; Russell, Martin; Billingham, Lucinda

    2016-01-01

    BACKGROUND: Bony metastatic castration-refractory prostate cancer is associated with a poor prognosis and high morbidity. TRAPEZE was a two-by-two factorial randomised controlled trial of zoledronic acid (ZA) and strontium-89 (Sr-89), each combined with docetaxel. All have palliative benefits, are used to control bone symptoms and are used with docetaxel to prolong survival. ZA, approved on the basis of reducing skeletal-related events (SREs), is commonly combined with docetaxel in practice, although evidence of efficacy and cost-effectiveness is lacking. Sr-89, approved for controlling metastatic pain and reducing need for subsequent bone treatments, is generally palliatively used in patients unfit for chemotherapy. Phase II analysis confirmed the safety and feasibility of combining these agents. TRAPEZE aimed to determine the clinical effectiveness and cost-effectiveness of each agent. METHODS: Patients were randomised to receive six cycles of docetaxel plus prednisolone: alone, with ZA, with a single Sr-89 dose after cycle 6, or with both. Primary outcomes were clinical progression-free survival (CPFS: time to pain progression, SRE or death) and cost-effectiveness. Secondary outcomes were SRE-free interval (SREFI), total SREs, overall survival (OS) and quality of life (QoL). Log-rank test and Cox regression modelling were used to determine clinical effectiveness. Cost-effectiveness was assessed from the NHS perspective and expressed as cost per additional quality-adjusted life-year (QALY). An additional analysis was carried out for ZA to reflect the availability of generic ZA. RESULTS: PATIENTS: 757 randomised (median age 68.7 years; Eastern Cooperative Oncology Group scale score 0, 40%; 1, 52%; 2, 8%; prior radiotherapy, 45%); median prostate-specific antigen 143.78 ng/ml (interquartile range 50.8-353.9 ng/ml). Stratified log-rank analysis of CPFS was statistically non-significant for either agent (Sr-89, p = 0.11; ZA, p = 0.45). Cox regression

  4. On the Effects of Heterogeneous Packet Lengths on Network Coding

    DEFF Research Database (Denmark)

    Compta, Pol Torres; Fitzek, Frank; Roetter, Daniel Enrique Lucani

    best case scenario as coded packets will incur little overhead to handle such packets. However, packet lengths are quite heterogeneous in real networks, which can cause a high overhead or, alternatively, a high delay in the transmission of data packets. As we show, this can have a severe effect on a...... variety of applications. This paper proposes a series of mechanisms to manage heterogeneous packet lengths and analyzes the induced overhead of those mechanisms using real packet length distributions provided by CAIDA and own measurements using video content. Our results show that an appropriate...... packetization of the data packets can reduce the overhead from over 100% (zero-padding packets) to below 5% for CAIDA packet distributions and that the right choice of parameters can reduce the overhead to less than 10% in the case of video data....

  5. Continuous Trading Dynamically Effectively Complete Market with Heterogeneous Beliefs

    DEFF Research Database (Denmark)

    Qin, Zhenjiang

    In a framework of heterogeneous beliefs, I investigate a two-date consumption model with continuous trading over the interval [0; T], in which information on the aggregate consumption at time T is revealed by an Ornstein-Uhlenbeck Bridge. This information structure allows investors to speculate on...... the heterogeneous posterior variance of dividend throughout [0; T). The market populated with many time-additive exponential-utility investors is dynamically effectively complete, if investors are allowed to trade in only two long-lived securities continuously. The underlying mechanism is that these...... measurable with respect to the aggregate consumption. With normally distributed dividend, the equilibrium stock price is endogenized in a Radner equilibrium as a precision weighted average of the investors’ posterior mean minus a risk premium determined by the average posterior precision. The stock price is...

  6. Frequency-dependent effective hydraulic conductivity of strongly heterogeneous media.

    Science.gov (United States)

    Caspari, E; Gurevich, B; Müller, T M

    2013-10-01

    The determination of the transport properties of heterogeneous porous rocks, such as an effective hydraulic conductivity, arises in a range of geoscience problems, from groundwater flow analysis to hydrocarbon reservoir modeling. In the presence of formation-scale heterogeneities, nonstationary flows, induced by pumping tests or propagating elastic waves, entail localized pressure diffusion processes with a characteristic frequency depending on the pressure diffusivity and size of the heterogeneity. Then, on a macroscale, a homogeneous equivalent medium exists, which has a frequency-dependent effective conductivity. The frequency dependence of the conductivity can be analyzed with Biot's equations of poroelasticity. In the quasistatic frequency regime of this framework, the slow compressional wave is a proxy for pressure diffusion processes. This slow compressional wave is associated with the out-of-phase motion of the fluid and solid phase, thereby creating a relative fluid-solid displacement vector field. Decoupling of the poroelasticity equations gives a diffusion equation for the fluid-solid displacement field valid in a poroelastic medium with spatial fluctuations in hydraulic conductivity. Then, an effective conductivity is found by a Green's function approach followed by a strong-contrast perturbation theory suggested earlier in the context of random dielectrics. This theory leads to closed-form expressions for the frequency-dependent effective conductivity as a function of the one- and two-point probability functions of the conductivity fluctuations. In one dimension, these expressions are consistent with exact solutions in both low- and high-frequency limits for arbitrary conductivity contrast. In 3D, the low-frequency limit depends on the details of the microstructure. However, the derived approximation for the effective conductivity is consistent with the Hashin-Shtrikman bounds. PMID:24229128

  7. Tailgut cyst accompanied with bony defect.

    Science.gov (United States)

    Oh, Jae-Sang; Shim, Jai-Joon; Lee, Kyeong-Seok; Doh, Jae-Won

    2016-04-01

    Retro-rectal cystic hamartoma (tailgut cyst), is an uncommon congenital developmental lesion, generally located in the retro-rectal space. Its diagnosis and approach is challenging because the retropelvic space is not familiar. We report a 51-year-old woman who presented with paresthesia and pain in perianal area. The magnetic resonance image showed high signal intensity on the T1-weighted image and iso to high signal intensity on the T2-weighted image of the retropelvic space and CT showed sacral bony defect. We chose the posterior approach for removal of the tailgut cyst. Histopathology exam of the retropelvic cyst revealed a multiloculated cyst containing abundant mucoid material lined by both squamous and glandular mucinous epithelium. The patient has recovered nicely with no recurrence. Tailgut cyst needs complete surgical excision for good prognosis. So, a preoperative high-resolution image and co-operation between neurosurgen and general surgeon would help to make safe and feasible diagnosis and surgical access. PMID:27073796

  8. Effect of Heterogeneity of JSFR Fuel Assemblies to Power Distribution

    International Nuclear Information System (INIS)

    Conclusion: 1) Strong heterogeneity of JSFR assemblies was successfully calculated by BACH. 2) Verification test of BACH: • Infinite assembly model; • Color set model; • Good agreement with Monte-Carlo results. 3) Core calculations 3 models for inner duct was used; inward model, outward model and homogeneous model. • keff difference between the inward and out ward model → 0.3%Δk; • ~20% effect on flux and power distributions. Therefore, we have to pay careful attention for the location of inner duct in fuel loading of JSFR

  9. Effects of Diffusive Property Heterogeneity on Effective Matrix Diffusion Coefficient for Fractured Rock

    OpenAIRE

    Zhang, Yingqi; Liu, Hui-Hai; Zhou, Quanlin; Finsterle, Stefan

    2005-01-01

    Heterogeneities of diffusion properties are likely to influence the effective matrix diffusion coefficient determined from tracer breakthrough curves. The objectives of this study are (1) to examine if it is appropriate to use a single, effective matrix diffusion coefficient to predict breakthrough curves in a fractured formation, (2) to examine if a postulated scale dependence of the effective matrix diffusion coefficient is caused by heterogeneity in diffusion properties, and (3) to ex...

  10. Hydrological effects of within-catchment heterogeneity of drainage density

    Science.gov (United States)

    Di Lazzaro, Michele; Zarlenga, Antonio; Volpi, Elena

    2015-02-01

    Local drainage density (dd) has been traditionally defined as the inverse of twice the distance one has to walk before encountering a channel. This formalization easily allows to derive raster-based maps of dd extracted straight off from digital elevation model data. Maps of local dd, which are continuous in space, are able to reveal the appearance of strong heterogeneities in the geological and geomorphological properties of natural landscapes across different scales. In this work we employ the information provided by these spatial maps to study the potential effects of the within-catchment variability of dd on the hydrologic response. A simple power law relationship between runoff yield at the local scale and the value of dd has been adopted; the hypothesis is supported by a large number of past empirical observations and modeling. The novel framework proposed (ddRWF) embeds this spatially variable runoff weight in the well-known Rescaled Width Function (RWF) framework, based on the more general geomorphological theory of the hydrologic response. The model is applied to four sub-basins in the Cascade Range Region (Oregon, USA) where strong contrasts in dissection patterns due the underlain geology have been broadly addressed in previous literature. The ddRWF approach is compared with the classic RWF in terms of shape, moments and peak of the simulated hydrograph response. Results hint that the variability of runoff yield due to the heterogeneity of dd (i.e. of hillslope lengths) determines a more rapid concentration of runoff, which implies shorter lag times, larger skewness and higher peak floods, especially in the case hillslope velocity is much smaller than channel velocity. The potential of the proposed framework relies on accounting for spatially variable losses related to geomorphologic heterogeneity in lumped rainfall-runoff models, still keeping the simple and robust structure of the IUH approach.

  11. Epithelial myoepithelial carcinoma in nasal cavity with bony destruction: A case report

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Ho Jin; Lee, Byung Hoon; Hwang, Yoon Joon; Kim, Su Young [Dept. of Radiology, Ilsan Paik Hospital, Inje University School of Medicine, Goyang , (Korea, Republic of)

    2013-10-15

    Epithelial-myoepithelial carcinoma (EMC) is a rare tumor that commonly involves the salivary glands. EMC arising from the nasal cavity is one of the most unusual cases. We describe a case of a 48-year-old patient who is presented with bilateral nasal obstruction for several months. Multidetector computed tomography reveals expansile, well-defined, heterogeneous enhancing soft tissue masses filling the nasal cavity with bony destruction of hard palate and maxillary alveolar ridge. The carcinoma was histologically characterized by a mixture of trabecular structure with myoepithelial cells and ductal cells, which are confirmed by electron microscopy and immunohistochemistry.

  12. Interphase thermodynamic bond in heterogeneous alloys: effects on alloy properties

    International Nuclear Information System (INIS)

    Inconsistency between a conventional thermodynamic description of alloys as a mechanical mixture of phases and a real alloys state as a common thermodynamic system in which there is a complicated physical-chemical phases interaction has been considered. It is supposed that in heterogeneous alloys (eutectic ones, for instance), so called interphase thermodynamic bond can become apparent due to a partial electron levels splitting under phase interaction. Thermodynamic description of phase equilibrium in alloys is proposed taking into account a thermodynamic bond for the system with phase diagram of eutectic type, and methods of the value of this bond estimation are presented. Experimental evidence (Al-Cu-Si, Al-Si-Mg-Cu, U-Mo + Al) of the effect of interphase thermodynamic bond on temperature and enthalpy of melting of alloys are produced as well as possibility of its effects on alloys electrical conduction, strength, heat and corrosion resistance is substantiated theoretically

  13. Treating Bony craters by osseous resection in periodontics: Crater therapy

    OpenAIRE

    V. Selahi Moghadam

    1989-01-01

    Treating bony craters by surgical method needs elimination or reduction of bony lesions as well as providing sufficient bone by minimum osteotomy in order to preserve supporting bone. Furcation preservation is very important. Most mandibular molars are overtreated from buccal aspect that leads to inverted morphology and affects buccal forcation. Identifying anatomical structures and their relation to lesions is essential. In crater therapy, furcation and tooth trunk are two ...

  14. Effects of Dipole Potential Modifiers on Heterogenic Lipid Bilayers.

    Science.gov (United States)

    Efimova, Svetlana S; Malev, Valery V; Ostroumova, Olga S

    2016-04-01

    In this work, we examine the ability of dipole modifiers, flavonoids, and RH dyes to affect the dipole potential (φ d) and phase separation in membranes composed of ternary mixtures of POPC with different sphingolipids and sterols. Changes in the steady-state conductance induced by cation-ionophore complexes have been measured to evaluate the changes in dipole potential of planar lipid bilayers. Confocal fluorescence microscopy has been employed to investigate lipid segregation in giant unilamellar vesicles. The effects of flavonoids on φ d depend on lipid composition and dipole modifier type. The effectiveness of RH dyes to increase φ d depends on sphingolipid type but is not influenced by sterol content. Tested modifiers lead to partial or complete disruption of gel domains in bilayers composed of POPC, sphingomyelin, and cholesterol. Substitution of cholesterol to ergosterol or 7-dehydrocholesterol leads to a loss of fluidizing effects of modifiers except phloretin. This may be due to various compositions of gel domains. The lack of influence of modifiers on phase scenario in vesicles composed of ternary mixtures of POPC, cholesterol, and phytosphingosine or sphinganine is related to an absence of gel-like phase. It was concluded that the membrane lateral heterogeneity affects the dipole-modifying abilities of the agents that influence the magnitude of φ d by intercalation into the bilayer and orientation of its own large dipole moments (phloretin and RH dyes). The efficacy of modifiers that do not penetrate deeply and affect φ d through water adsorption (phlorizin, quercetin, and myricetin) is not influenced by lateral heterogeneity of membrane. PMID:26454655

  15. Heterogeneous Deployment Analysis for Cost-Effective Mobile Network Evolution

    DEFF Research Database (Denmark)

    Coletti, Claudio

    2013-01-01

    The plethora of connected devices, such as attractive smartphones, data dongles and 3G/4G built-in tablet computers, has brought mobile operators to face increasing demand in mobile broadband traffic and services. In addition to the roll-out of Long Term Evolution (LTE), the deployment of small low......-powered base stations is a promising cost-effective solution to considerably enhance user experience. In such a network topology, which is denoted as heterogeneous deployment, the macro layer is expected to provide wider coverage but lower average data speeds whereas small cells are targeted at extending...... network coverage and boosting network capacity in traffic hot-spot areas. The thesis deals with the deployment of both outdoor small cells and indoor femto cells. Amongst the outdoor solution, particular emphasis is put on relay base stations as backhaul costs can be reduced by utilizing LTE spectrum...

  16. Effective IPTV channel management method over heterogeneous environments

    Science.gov (United States)

    Joo, Hyunchul; Lee, Dai-boong; Song, Hwangjun

    2007-09-01

    This paper presents an effective IPTV channel management method using SVC (scalable video coding) that considers concurrently both channel zapping time and network utilization. A broadcasting channel is encoded in two-layered bitstream (base-layer channel and enhancement-layer channel) to supply for heterogeneous environments. The proposed algorithm locates only a limited numbers of base-layer channels close to users to reduce the network delay part of channel zapping time and adjusts the length of GOP (group of picture) into each base-layer channel to decrease the video decoding delay part of channel zapping time, which are performed based on user's channel preference information. Finally, the experimental results are provided to show the performance of the proposed schemes.

  17. Elastic and plastic effects on heterogeneous nucleation and nanowire formation

    Science.gov (United States)

    Boussinot, G.; Schulz, R.; Hüter, C.; Brener, E. A.; Spatschek, R.

    2014-02-01

    We investigate theoretically the effects of elastic and plastic deformations on heterogeneous nucleation and nanowire formation. In the first case, the influence of the confinement of the critical nucleus between two parallel misfitting substrates is investigated using scaling arguments. We present phase diagrams giving the nature of the nucleation regime as a function of the driving force and the degree of confinement. We complement this analytical study by amplitude equations simulations. In the second case, the influence of a screw dislocation inside a nanowire on the development of the morphological surface instability of the wire, related to the Rayleigh-Plateau instability, is examined. Here the screw dislocation provokes a torsion of the wire known as Eshelby twist. Numerical calculations using the finite element method and the amplitude equations are performed to support analytical investigations. It is shown that the screw dislocation promotes the Rayleigh-Plateau instability.

  18. The effects of physical and geochemical heterogeneities on hydro-geochemical transport and effective reaction rates

    Science.gov (United States)

    Atchley, Adam L.; Navarre-Sitchler, Alexis K.; Maxwell, Reed M.

    2014-09-01

    The role of coupled physical and geochemical heterogeneities in hydro-geochemical transport is investigated by simulating three-dimensional transport in a heterogeneous system with kinetic mineral reactions. Ensembles of 100 physically heterogeneous realizations were simulated for three geochemical conditions: 1) spatially homogeneous reactive mineral surface area, 2) reactive surface area positively correlated to hydraulic heterogeneity, and 3) reactive surface area negatively correlated to hydraulic heterogeneity. Groundwater chemistry and the corresponding effective reaction rates were calculated at three transverse planes to quantify differences in plume evolution due to heterogeneity in mineral reaction rates and solute residence time (τ). The model is based on a hypothetical CO2 intrusion into groundwater from a carbon capture utilization and storage (CCUS) operation where CO2 dissolution and formation of carbonic acid created geochemical dis-equilibrium between fluids and the mineral galena that resulted in increased aqueous lead (Pb2 +) concentrations. Calcite dissolution buffered the pH change and created conditions of galena oversaturation, which then reduced lead concentrations along the flow path. Near the leak kinetic geochemical reactions control the release of solutes into the fluid, but further along the flow path mineral solubility controls solute concentrations. Simulation results demonstrate the impact of heterogeneous distribution of geochemical reactive surface area in coordination with physical heterogeneity on the effective reaction rate (Krxn,eff) and Pb2 + concentrations within the plume. Dissimilarities between ensemble Pb2 + concentration and Krxn,eff are attributed to how geochemical heterogeneity affects the time (τeq) and therefore advection distance (Leq) required for the system to re-establish geochemical equilibrium. Only after geochemical equilibrium is re-established, Krxn,eff and Pb2 + concentrations are the same for all three

  19. Effects of lung inflation on airway heterogeneity during histaminergic bronchoconstriction.

    Science.gov (United States)

    Kaczka, David W; Mitzner, Wayne; Brown, Robert H

    2013-09-01

    Lung inflation has been shown to dilate airways by altering the mechanical equilibrium between opposing airway and parenchymal forces. However, it is not known how heterogeneously such dilation occurs throughout the airway tree. In six anesthetized dogs, we measured the diameters of five to six central airway segments using high-resolution computed tomography, along with respiratory input impedance (Zrs) during generalized aerosol histamine challenge, and local histamine challenge in which the agonist was instilled directly onto the epithelia of the imaged central airways. Airway diameters and Zrs were measured at 12 and 25 cmH2O. The Zrs spectra were fitted with a model that incorporated continuous distributions of airway resistances. Airway heterogeneity was quantified using the coefficient of variation for predefined airway distribution functions. Significant reductions in average central airway diameter were observed at 12 cmH2O for both aerosolized and local challenges, along with significant increases upon inflation to 25 cmH2O. No significant differences were observed for the coefficient of variation of airway diameters under any condition. Significant increases in effective airway resistance as measured by Zrs were observed only for the aerosolized challenge at 12 cmH2O, which was completely reversed upon inflation. We conclude that the lung periphery may be the most dominant contributor to increases in airway resistance and tissue elastance during bronchoconstriction induced by aerosolized histamine. However, isolated constriction of only a few central airway segments may also affect tissue stiffness via interdependence with their surrounding parenchyma. PMID:23813528

  20. The Effects of Japanese Interventions on FX-Forecast Heterogeneity

    OpenAIRE

    Reitz, Stefan; Stadtmann, Georg; Taylor, Mark P

    2009-01-01

    This paper investigates the determinants of forecast heterogeneity in the Yen-US dollar market using a panel data set from Consensus Economics. Regardless of the particular model specification and consideration of control variables we find that exchange rate misalignments increase forecast dispersion, while foreign exchange intervention of the Japanese Ministry of Finance dampens expectation heterogeneity.

  1. Effects of reservoir heterogeneity on scaling of effective mass transfer coefficient for solute transport

    Science.gov (United States)

    Leung, Juliana Y.; Srinivasan, Sanjay

    2016-09-01

    Modeling transport process at large scale requires proper scale-up of subsurface heterogeneity and an understanding of its interaction with the underlying transport mechanisms. A technique based on volume averaging is applied to quantitatively assess the scaling characteristics of effective mass transfer coefficient in heterogeneous reservoir models. The effective mass transfer coefficient represents the combined contribution from diffusion and dispersion to the transport of non-reactive solute particles within a fluid phase. Although treatment of transport problems with the volume averaging technique has been published in the past, application to geological systems exhibiting realistic spatial variability remains a challenge. Previously, the authors developed a new procedure where results from a fine-scale numerical flow simulation reflecting the full physics of the transport process albeit over a sub-volume of the reservoir are integrated with the volume averaging technique to provide effective description of transport properties. The procedure is extended such that spatial averaging is performed at the local-heterogeneity scale. In this paper, the transport of a passive (non-reactive) solute is simulated on multiple reservoir models exhibiting different patterns of heterogeneities, and the scaling behavior of effective mass transfer coefficient (Keff) is examined and compared. One such set of models exhibit power-law (fractal) characteristics, and the variability of dispersion and Keff with scale is in good agreement with analytical expressions described in the literature. This work offers an insight into the impacts of heterogeneity on the scaling of effective transport parameters. A key finding is that spatial heterogeneity models with similar univariate and bivariate statistics may exhibit different scaling characteristics because of the influence of higher order statistics. More mixing is observed in the channelized models with higher-order continuity. It

  2. Effects of reservoir heterogeneity on scaling of effective mass transfer coefficient for solute transport.

    Science.gov (United States)

    Leung, Juliana Y; Srinivasan, Sanjay

    2016-09-01

    Modeling transport process at large scale requires proper scale-up of subsurface heterogeneity and an understanding of its interaction with the underlying transport mechanisms. A technique based on volume averaging is applied to quantitatively assess the scaling characteristics of effective mass transfer coefficient in heterogeneous reservoir models. The effective mass transfer coefficient represents the combined contribution from diffusion and dispersion to the transport of non-reactive solute particles within a fluid phase. Although treatment of transport problems with the volume averaging technique has been published in the past, application to geological systems exhibiting realistic spatial variability remains a challenge. Previously, the authors developed a new procedure where results from a fine-scale numerical flow simulation reflecting the full physics of the transport process albeit over a sub-volume of the reservoir are integrated with the volume averaging technique to provide effective description of transport properties. The procedure is extended such that spatial averaging is performed at the local-heterogeneity scale. In this paper, the transport of a passive (non-reactive) solute is simulated on multiple reservoir models exhibiting different patterns of heterogeneities, and the scaling behavior of effective mass transfer coefficient (Keff) is examined and compared. One such set of models exhibit power-law (fractal) characteristics, and the variability of dispersion and Keff with scale is in good agreement with analytical expressions described in the literature. This work offers an insight into the impacts of heterogeneity on the scaling of effective transport parameters. A key finding is that spatial heterogeneity models with similar univariate and bivariate statistics may exhibit different scaling characteristics because of the influence of higher order statistics. More mixing is observed in the channelized models with higher-order continuity. It

  3. Heterogeneous Effects of Direct Hypoxia Pathway Activation in Kidney Cancer.

    Directory of Open Access Journals (Sweden)

    Rafik Salama

    Full Text Available General activation of hypoxia-inducible factor (HIF pathways is classically associated with adverse prognosis in cancer and has been proposed to contribute to oncogenic drive. In clear cell renal carcinoma (CCRC HIF pathways are upregulated by inactivation of the von-Hippel-Lindau tumor suppressor. However HIF-1α and HIF-2α have contrasting effects on experimental tumor progression. To better understand this paradox we examined pan-genomic patterns of HIF DNA binding and associated gene expression in response to manipulation of HIF-1α and HIF-2α and related the findings to CCRC prognosis. Our findings reveal distinct pan-genomic organization of canonical and non-canonical HIF isoform-specific DNA binding at thousands of sites. Overall associations were observed between HIF-1α-specific binding, and genes associated with favorable prognosis and between HIF-2α-specific binding and adverse prognosis. However within each isoform-specific set, individual gene associations were heterogeneous in sign and magnitude, suggesting that activation of each HIF-α isoform contributes a highly complex mix of pro- and anti-tumorigenic effects.

  4. Occult bony lesions associated with anterior cruciate ligament injury

    International Nuclear Information System (INIS)

    To examine bony lesions associated with anterior cruciate ligament (ACL) injuries, magnetic resonance (MR) imaging was performed on 55 knees with ACL injuries. With respect to the period between ACL injuries and MR imaging, the knees were divided into acute (within one month), subacute (from one month to one year) and chronic (over one year) groups, containing 19, 16 and 20 knees, respectively. Occult bony lesions not shown in roentgenography were observed more frequently in the acute group (13/19) than in the other two groups (subacute group, 5/16; chronic group, 1/20), located in the lateral compartment of the knee joint. In the acute group, bony lesions had high signal intensity on T2-weighted images and low signal intensity on proton density images. In the subacute and chronic groups, bony lesions were less pronounced and had low signal intensity on T2-weighted images. These findings suggest that bony lesions are frequently associated with and occur simultaneously with ACL injury. (author)

  5. Bony Lesions in Pediatric Acute Leukemia: Pictorial Essay

    Directory of Open Access Journals (Sweden)

    Makhtoom Shahnazi

    2012-03-01

    Full Text Available Acute leukemia is the most common malignancy in childhood, which mainly involves children less than 15 years of age. The growing skeleton is the main site of involvement in children. Leukemic cells proliferate within the massive red bone marrow in children. So besides the pallor, petechia, purpura and ecchymosis in the skin and mucosal surfaces, bone pain and other bony lesions are other manifestations of leukemia.On the other hand, bony lesions are more prevalent in children than adults with no poor prognosis in comparison to patients without bone lesions. These bony lesions may precede other laboratory tests so familiarity with these presentations is very important for earlier diagnosis.In this pictorial essay, we tried to gather the most common bony lesions that may be seen in acute leukemia in different cases admitted to our hospital with general malaise and localized tenderness and discomfort leading us to perform plain X-ray for further evaluation. Finding these bony lesions helps clinicians to reach the diagnosis quickly. These findings include metaphyseal lucent band and erosion, periosteal reaction, small lucent bone lesion and permeative appearance, reduced bone density and collapsed vertebra.

  6. The effect of heterogeneity on invasion in spatial epidemics

    DEFF Research Database (Denmark)

    Neri, Franco M; Bates, Anne; Füchtbauer, Winnie Sophie;

    2011-01-01

    paradigm” to the spread of a pathogen in discrete heterogeneous host populations. In particular, we test the hypothesis that the probability of epidemic invasion decreases when host heterogeneity is increased. We use replicated experimental microcosms, in which the ubiquitous pathogenic fungus Rhizoctonia...... agreement with the theoretical predictions. We briefly discuss how our results can be exploited in the design and implementation of disease control strategies...

  7. Migration Effects of Parallel Genetic Algorithms on Line Topologies of Heterogeneous Computing Resources

    Science.gov (United States)

    Gong, Yiyuan; Guan, Senlin; Nakamura, Morikazu

    This paper investigates migration effects of parallel genetic algorithms (GAs) on the line topology of heterogeneous computing resources. Evolution process of parallel GAs is evaluated experimentally on two types of arrangements of heterogeneous computing resources: the ascending and descending order arrangements. Migration effects are evaluated from the viewpoints of scalability, chromosome diversity, migration frequency and solution quality. The results reveal that the performance of parallel GAs strongly depends on the design of the chromosome migration in which we need to consider the arrangement of heterogeneous computing resources, the migration frequency and so on. The results contribute to provide referential scheme of implementation of parallel GAs on heterogeneous computing resources.

  8. Circumferential Calcification of Silicone Implant Misunderstood as a Bony Substitute.

    Science.gov (United States)

    Lee, Sae Bin; Min, Hyun Jin

    2016-01-01

    Silicone implant is known to be safe and easy to handle, and frequently used in Asian rhinoplasty. Compared with breast implant, complication studies about silicone calcification used in rhinoplasty are very limited. Recently, the authors experienced an interesting patient who underwent revision rhinoplasty in our institution. Based on preoperative images, previously inserted dorsal augmentation material was identified. It was circumferentially enclosed with bony material and hypertrophied bony lesion induced hump on the mid portion of nasal dorsum. During operation, the authors found it was the calcified capsule of silicone implant, and the calcification was surrounding the whole implant material. PMID:26703034

  9. Heterogenization of Homogeneous Catalysts: the Effect of the Support

    Energy Technology Data Exchange (ETDEWEB)

    Earl, W.L.; Ott, K.C.; Hall, K.A.; de Rege, F.M.; Morita, D.K.; Tumas, W.; Brown, G.H.; Broene, R.D.

    1999-06-29

    We have studied the influence of placing a soluble, homogeneous catalyst onto a solid support. We determined that such a 'heterogenized' homogeneous catalyst can have improved activity and selectivity for the asymmetric hydrogenation of enamides to amino acid derivatives. The route of heterogenization of RhDuPhos(COD){sup +} cations occurs via electrostatic interactions with anions that are capable of strong hydrogen bonding to silica surfaces. This is a novel approach to supported catalysis. Supported RhDuPhos(COD){sup +} is a recyclable, non-leaching catalyst in non-polar media. This is one of the few heterogenized catalysts that exhibits improved catalytic performance as compared to its homogeneous analog.

  10. Effects of host heterogeneity on pathogen diversity and evolution

    DEFF Research Database (Denmark)

    Fleming-Davies, Arietta E; Dukic, Vanja; Andreasen, Viggo;

    2015-01-01

    strategy for the pathogen: a low-transmission, low-variability type can coexist with the high-transmission type favoured by classical non-heterogeneity models. In addition, this tradeoff can help explain the extensive phenotypic variation we observed in field-collected pathogen isolates, in traits...... (Lymantria dispar) larvae. We found that an empirically observed tradeoff between mean transmission rate and variation in transmission, which results from host heterogeneity, promotes long-term coexistence of two pathogen types in simulations of a population model. This tradeoff introduces an alternative...... affecting virus fitness including transmission and environmental persistence. Similar heterogeneity tradeoffs might be a general mechanism promoting phenotypic variation in any pathogen for which hosts vary continuously in susceptibility....

  11. Heterogeneity in Consumer Demands and the Income Effect

    DEFF Research Database (Denmark)

    Christensen, Mette

    2014-01-01

    This paper uses unique Spanish panel data on household expenditures to test whether unobservable heterogeneity in household demands (taste, etc.) is correlated with total expenditures (income). The main finding is that tastes are indeed correlated with income for about half of the goods considered......, implying that cross-sectional estimates of income elasticities for these goods are biased. The goods are the following: food eaten outside home, alcohol and tobacco, transportation, and energy. The elasticity of alcohol and tobacco is more than halved when taking unobserved heterogeneity into account. For...

  12. Bony exostosis of the atlas with resultant cranial nerve palsy

    International Nuclear Information System (INIS)

    A case of tenth and twelfth nerve compression secondary to a bony exostosis of the first cervical vertebra is described. This uncommon phenomenon serves to outline the importance of imaging the course of a cranial nerve when no intracranial abnormality is demonstrable on CT or MRI. The radiologic features of spinal osteochondromas are reviewed. (orig.)

  13. Arthroscopic treatment of bony loose bodies in the subacromial space

    Directory of Open Access Journals (Sweden)

    Wei Li

    2015-01-01

    Conclusion: The mechanism of formation of bony loose bodies is not clear, may be associated with synovial cartilage metaplasia. Arthroscopic removal of loose bodies and bursa debridement is a good option for treatment of the loose body in the subacromial space, which can receive good function.

  14. Effect of distance on trade under slope heterogeneity and cross-correlated effects

    OpenAIRE

    Lugovskyy, Oleksandr; Skiba, Alexandre

    2014-01-01

    The authors argue that endogeneity of transportation costs needs to be taken into account when estimating the effect of distance on trade. Otherwise, the estimates of the distance effect may be biased and inconsistent. Endogenous transportation can introduce slope heterogeneity and spatial correlation. Both issues can be accommodated with the help of Pesaran's cross-correlated effects mean-group (CCEMG) estimator. After applying this methodology, the authors uncover significant compression of...

  15. The Heterogeneous Effects of Income Changes on Happiness

    Science.gov (United States)

    Becchetti, Leonardo; Corrado, Luisa; Rossetti, Fiammetta

    2011-01-01

    We investigate the relationship between money and happiness across the waves of the British Household Panel Study by using a latent class approach which accounts for slope heterogeneity. Our findings reveal the presence of a vast majority of "Easterlin-type" individuals with positive but very weak relationship between changes in income and changes…

  16. Laboratory investigations of effective flow behavior in unsaturated heterogeneous sands

    DEFF Research Database (Denmark)

    Wildenschild, Dorthe; Høgh Jensen, Karsten

    1999-01-01

    controlled method. The heterogeneous sand systems were established in a laboratory tank for three realizations of random distributions of the homogeneous sands comprising a system of 207 grid cells. The water flux was controlled at the upper boundary, while a suction was applied at the lower boundary such...

  17. Calculation of Heterogeneity Effects in Fast Critical Assemblies

    International Nuclear Information System (INIS)

    The physical properties of the fast power reactor cores with respect to the neutron transport are usually not essentially influenced by the heterogeneity of the core structure. Nevertheless, when modelling the cores of these reactors by experimental critical assemblies the heterogeneity of the structure becomes essentially greater and cannot be neglected in the analysis of experiments. In connection with this fact a further development of the previously presented method of homogenization of slab lattices with respect to the chain reaction with fast neutrons is contributed. Attention is restricted to bare assemblies made up of a periodic lattice of parallel slabs of two different materials, a so-called ''sandwich'' reactor of materials 1 and 2. The geometry considered is (a) the plane geometry with boundaries parallel to the slabs, (b) the plane geometry with boundaries perpendicular to the slabs, and (c) the cylindrical geometry with boundaries perpendicular to the slabs with infinite or finite height. The restriction to two different media is made because of a simplification only and is not substantial. The starting point is the integral transport theory based on the solution of the kinetic Boltzmann equation. The solution is sought in the form of a product of asymptotic transport theory solution characterized by the buckling B2 and representing the general trend of the neutron emission density with the fine structure, taking account of the heterogeneous structure of alternative layers of media 1 and 2. As a result the value of the buckling B2 of the heterogeneous assembly together with energy spectra in each medium is obtained. As an illustration of the method the chain reaction with fast neutrons in a heterogeneous medium consisting of 235U and 238U plates placed in turn is investigated. For 16 energy groups the buckling B2 and the energy spectrum in 235U and 238U have been calculated for a 10%, 20% and 30% enrichment with 235U for different cell dimensions of

  18. Individuals' Unemployment Experiences: Heterogeneity and Business Cycle Effects

    OpenAIRE

    Kalwij, Adriaan S.

    2001-01-01

    This study examines individuals? unemployment experiences from the age of 18 up to the age of 35 using a large panel of administrative records on unemployment related benefit claims of men in the United Kingdom over the past two decades. The main focus is on the extent to which individuals? unemployment experiences are affected by regional and skill differences, i.e. individual heterogeneity, and the business cycle. In particular this study analyses the extent to which repeated unemployment i...

  19. Dynamic effects of increasing heterogeneity in financial markets

    International Nuclear Information System (INIS)

    Despite canonical behavioural financial market models [Day R, Huang W. Bulls, bears and market sheep. J Econ Behav Org 1990;14:299-329], that use different types of agents (i.e., fundamentalist vs. chartists), we develop a model in which the source of instability is the interaction of groups that are homogeneous in the strategy they use, but have heterogeneous beliefs about the fundamental value of the asset. Specifically, heterogeneity arises among two groups of fundamentalists that follow gurus. We show that an increasing distance between beliefs (the degree of heterogeneity), leads first (i) to a pitchfork bifurcation to arise secondly (ii) it generates, together with a larger reaction to misalignment of both market maker and agents, the appearance of a periodic, or even, chaotic, price fluctuation; (iii) finally a homoclinic bifurcation [Dieci R, Bischi GI, Gardini L. From bi-stability to chaotic oscillations in a macroeconomic model. Chaos, Solitons and Fractals 2001;12:805-22] transforms a two piece chaotic set into a one piece chaotic set that generates bull and bear markets.

  20. Imaging of the hip and bony pelvis. Techniques and applications

    Energy Technology Data Exchange (ETDEWEB)

    Davies, A.M. [Royal Orthopaedic Hospital, Birmingham (United Kingdom). MRI Centre; Johnson, K.J. [Princess of Wales Birmingham Children' s Hospital (United Kingdom); Whitehouse, R.W. (eds.) [Manchester Royal Infirmary (United Kingdom). Dept. of Clinical Radiology

    2006-07-01

    This is a comprehensive textbook on imaging of the bony pelvis and hip joint that provides a detailed description of the techniques and imaging findings relevant to this complex anatomical region. In the first part of the book, the various techniques and procedures employed for imaging the pelvis and hip are discussed in detail. The second part of the book documents the application of these techniques to the diverse clinical problems and diseases encountered. Among the many topics addressed are congenital and developmental disorders including developmental dysplasia of the hip, irritable hip and septic arthritis, Perthes' disease and avascular necrosis, slipped upper femoral epiphysis, bony and soft tissue trauma, arthritis, tumours and hip prostheses. Each chapter is written by an acknowledged expert in the field, and a wealth of illustrative material is included. This book will be of great value to musculoskeletal and general radiologists, orthopaedic surgeons and rheumatologists. (orig.)

  1. Homogeneous-heterogeneous reaction effects in peristalsis through curved geometry

    Science.gov (United States)

    Hayat, Tasawar; Tanveer, Anum; Alsaadi, Fuad; Alotaibi, Naif D.

    2015-06-01

    This paper looks at the influence of homogeneous-heterogeneous reactions on the peristaltic transport of non-Newtonian fluid in a curved channel with wall properties. Constitutive relations for thermodynamic third grade material are utilized in the problem development. An electrically conducting fluid in the presence of radial applied magnetic field is considered. The governing flow equations are developed in the presence of viscous heating. Mathematical computations are simplified employing long wavelength and low Reynolds number considerations. The solutions for velocity, temperature, concentration and heat transfer coefficient are obtained and examined. The features of sundry parameters are analyzed by plotting graphs.

  2. Homogeneous-heterogeneous reaction effects in peristalsis through curved geometry

    Directory of Open Access Journals (Sweden)

    Tasawar Hayat

    2015-06-01

    Full Text Available This paper looks at the influence of homogeneous-heterogeneous reactions on the peristaltic transport of non-Newtonian fluid in a curved channel with wall properties. Constitutive relations for thermodynamic third grade material are utilized in the problem development. An electrically conducting fluid in the presence of radial applied magnetic field is considered. The governing flow equations are developed in the presence of viscous heating. Mathematical computations are simplified employing long wavelength and low Reynolds number considerations. The solutions for velocity, temperature, concentration and heat transfer coefficient are obtained and examined. The features of sundry parameters are analyzed by plotting graphs.

  3. Homogeneous-heterogeneous reaction effects in peristalsis through curved geometry

    Energy Technology Data Exchange (ETDEWEB)

    Hayat, Tasawar [Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan); Department of Electrical and Computer Engineering, Faculty of Engineering, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Tanveer, Anum, E-mail: qau14@yahoo.com; Alsaadi, Fuad [Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan); Alotaibi, Naif D. [Department of Electrical and Computer Engineering, Faculty of Engineering, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

    2015-06-15

    This paper looks at the influence of homogeneous-heterogeneous reactions on the peristaltic transport of non-Newtonian fluid in a curved channel with wall properties. Constitutive relations for thermodynamic third grade material are utilized in the problem development. An electrically conducting fluid in the presence of radial applied magnetic field is considered. The governing flow equations are developed in the presence of viscous heating. Mathematical computations are simplified employing long wavelength and low Reynolds number considerations. The solutions for velocity, temperature, concentration and heat transfer coefficient are obtained and examined. The features of sundry parameters are analyzed by plotting graphs.

  4. Homogeneous-heterogeneous reaction effects in peristalsis through curved geometry

    International Nuclear Information System (INIS)

    This paper looks at the influence of homogeneous-heterogeneous reactions on the peristaltic transport of non-Newtonian fluid in a curved channel with wall properties. Constitutive relations for thermodynamic third grade material are utilized in the problem development. An electrically conducting fluid in the presence of radial applied magnetic field is considered. The governing flow equations are developed in the presence of viscous heating. Mathematical computations are simplified employing long wavelength and low Reynolds number considerations. The solutions for velocity, temperature, concentration and heat transfer coefficient are obtained and examined. The features of sundry parameters are analyzed by plotting graphs

  5. Effects of spatial plant-soil feedback heterogeneity on plant performance in monocultures

    OpenAIRE

    Wubs, E.R.J.; Bezemer, T.M.

    2016-01-01

    1. Plant-soil feedback (PSF) effects have almost exclusively been quantified on homogeneous soils, but as different plant species will influence their local soil differently in reality PSF effects will be spatially heterogeneous. Whether plant performance in soils with spatially heterogeneous PSF can be predicted from pot experiments with homogeneous soils is unclear. 2. In a greenhouse experiment we tested the response of monocultures of six grassland species (two grasses, two legumes, and t...

  6. Between Organism and Sky: Oscar Bony, 1965-1976

    Directory of Open Access Journals (Sweden)

    Daniel Quiles

    2014-06-01

    Full Text Available Oscar Bony was a key figure in the generation of avant-garde artists who famously broke with the Instituto Torcuato Di Tella in the wake of censorship at Experiencias ’68. He was also the official photographer for RCA’s affiliate record label in Argentina between 1967 and 1973, producing publicity for a new wave of rock n’ roll bands and solo popular music acts including Los Gatos and Arco Iris. Attending to key phases in his artistic oeuvre as well as close readings of his expertly crafted popular images, this article attempts to bridge these seemingly irreconcilable aspects of Bony’s practice. At first glance, his rock photography, known as el estilo Bony, has little relation to his art, and is perhaps even its political antithesis: “creative” work in the service of a top-down business model. Yet a closer look at both endeavors yields a lasting interplay between flesh and concept—at the grain of the work, a dialectic between incontrovertible index and crafted, calculated image—that was the artist’s central preoccupation in the fraught decade between the military coups. As such, Bony provides an opportunity to recover a category often absent from the Argentine art of this moment: the body, factual and libidinal.

  7. Canine hip dysplasia: significance of early bony spurring

    International Nuclear Information System (INIS)

    It is the purpose of this study to call attention to new bone production that often occurs early in the sequence of pathological changes associated with canine hip dysplasia. New bone production extending to bony remodeling, as well as femoral head subluxation, both occur in the sequence of pathologic changes associated with canine hip dysplasia. Subluxation is considered primary, while osteoarthrosis is a secondary feature, and both are used in the diagnosis of canine hip dysplasia. This report concerns the significance of the presence of a solitary bony osteophyte, or spur, that is frequently evident on the caudal aspect of the femoral neck as viewed on the conventional ventrodorsal projection. This report utilizes findings from pelvic radiographs of 605 dogs (five breeds). There was a greater frequency (54%)of this bony change in cases diagnosed radiographically as dysplastic than in cases diagnosed as normal(15%).Thus, it is suggested that this minimal radiographic change can be used as an indicator of early canine hip dysplasia, especially in the absence of subluxation of the femoral head

  8. Charge Transfer and Support Effects in Heterogeneous Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Hervier, Antoine [Univ. of California, Berkeley, CA (United States)

    2011-12-21

    the band bending at the interface, gives rise to a steady-state flow of hot holes to the surface. This leads to a decrease in turnover on the surface, an effect which is enhanced when a reverse bias is applied to the diode. Similar experiments were carried out for CO oxidation. On Pt/Si diodes, the reaction rate was found to increase when a forward bias was applied. When the diode was exposed to visible light and a reverse bias was applied, the rate was instead decreased. This implies that a flow of negative charges to the surface increases turnover, while positive charges decrease it. Charge flow in an oxide supported metal catalyst can be modified even without designing the catalyst as a solid state electronic device. This was done by doping stoichiometric and nonstoichiometric TiO2 films with F, and using the resulting oxides as supports for Pt films. In the case of stoichiometric TiO2, F was found to act as an n-type dopant, creating a population of filled electronic states just below the conduction band, and dramatically increasing the conductivity of the oxide film. The electrons in those states can transfer to surface O, activating it for reaction with CO, and leading to increased turnover for CO oxidation. This reinforces the hypothesis that CO oxidation is activated by a flow of negative charges to the surface. The same set of catalysts was used for methanol oxidation. The electronic properties of the TiO2 films again correlated with the turnover rates, but also with selectivity. With stoichiometric TiO2 as the support, F-doping caused an increase in selectivity toward the formation of partial oxidation products, formaldehyde and methyl formate, versus the total oxidation product, CO2. With non-stoichiometric TiO2, F-doping had the reverse effect. Ambient Pressure X-Ray Photoelectron Spectroscopy was used to investigate this F-doping effect in reaction conditions. In O2 alone, and in

  9. The effect of spatial variation in potential energy on the diffusion in heterogeneous media

    Science.gov (United States)

    Livshits, A. I.

    2016-05-01

    The standard equation of diffusion in heterogeneous media is found to be incomplete. The effect of heterogeneity on diffusion phenomena is commonly considered to be caused by only spatial variations of diffusion coefficient while the spatial difference in the potential energy of diffusing particles due to their interactions with the inhomogeneous medium is not taken into consideration. The possibility of new transport phenomena in heterogeneous media follows from the corrected equation. In particular the great increase of hydrogen permeability through the membranes of metallic alloy is turned out possible due to an optimization of spatial distribution of the alloy composition.

  10. Temperature effect on heterogeneity of microstrain distribution in steels

    International Nuclear Information System (INIS)

    Results of investigation into development of microheterogeneous deformation in steels in the temperature range of 800-1300 deg C are given. For the 0Kh13 ferritic steel the temperature increase results in continuous decrease of microdeformation heterogeneity level. For the 1Kh21N5T steel up to 1100 deg C Kh.d. decreases slightly and then on heating of up to 1300 deg C Kh.d. increases abruptly, at that, the higher austenite content in steel the swifter Kh.d. growth. For 08Kh18N10T steel up to 1200 deg C Kh.d. decreases and on further heating Kh.d. increases abruptly

  11. Effect of genetic heterogeneity and assortative mating on linkage analysis: a simulation study.

    OpenAIRE

    Falk, C T

    1997-01-01

    Linkage studies of complex genetic traits raise questions about the effects of genetic heterogeneity and assortative mating on linkage analysis. To further understand these problems, I have simulated and analyzed family data for a complex genetic disease in which disease phenotype is determined by two unlinked disease loci. Two models were studied, a two-locus threshold model and a two-locus heterogeneity model. Information was generated for a marker locus linked to one of the disease-definin...

  12. Which Farmers Benefit the Most from Bt Corn Adoption in the Philippines? Estimating Heterogeneity Effects

    OpenAIRE

    Mutuc, Maria Erlinda M.; Rejesus, Roderick M.; Yorobe, Jose M., Jr.

    2012-01-01

    The potential contributions of new biotechnologies to sustainable food and income security have been the subject of widespread discussions around the turn of the twenty-first century. But distributional issues of which segments of GMO adopters benefit the most have not been given ample attention. Using propensity scores, we apply the (a) stratification-multilevel method of estimating heterogeneous treatment effects (SM-HTE); and the (b) matching-smoothing method of estimating heterogeneous tr...

  13. Heterogeneous plastic deformation and Bauschinger effect in ultrafine-grained metals: atomistic simulations

    Science.gov (United States)

    Tsuru, Tomohito; Aoyagi, Yoshiteru; Kaji, Yoshiyuki; Shimokawa, Tomotsugu

    2016-03-01

    The effect of the dislocation density on yield strength and subsequent plastic deformation of ultrafine-grained metals was investigated in large-scale atomistic simulations. Polycrystalline models were constructed and uniaxial tension and compression were applied to elucidate the heterogeneous plastic deformation and the Bauschinger effect. The initial yield becomes heterogeneous as the dislocation density decreases owing to a wide range of Schmid factors of activated slip systems in each grain. A different mechanism of the Bauschinger effect was proposed, where the Bauschinger effect of ultrafine-grained metals is caused by the change in dislocation density in the process of forward and backward loadings.

  14. Treatment Effect Heterogeneity in a Science Professional Development Initiative: The Case for School Capacity

    Science.gov (United States)

    Bruch, Sarah; Grigg, Jeffrey; Hanselman, Paul

    2010-01-01

    This study focuses on how the treatment effects of a teacher professional development initiative in science differed by school capacity. In other words, the authors are primarily concerned with treatment effect heterogeneity. As such, this paper complements ongoing evaluation of the average treatment effects of the initiative over time. The…

  15. Correlation of Effective Dispersive and Polar Surface Energies in Heterogeneous Self-Assembled Monolayer Coatings

    DEFF Research Database (Denmark)

    Zhuang, Yanxin; Hansen, Ole

    2009-01-01

    We show, theoretically, that the measured effective dispersive and polar surface energies of a heterogeneous Surface are correlated; the correlation, however, differs whether a Cassic or an Israelachvili and Gee model is assumed. Fluorocarbon self-assembled monolayers with varying coverage were...... grown oil oxidized (100) silicon Surfaces in a vapor phase process using five different precursors. Experimentally, effective surface energy components of the fluorocarbon self-assembled monolayers were determined from measured contact angles using the Owens-Wendt-Rabel-Kaelble method. We show that the...... correlation between the effective surface energy components of the heterogeneous Surfaces coated with fluorocarbon self-assembled monolayers is in agreement with the Cassie model....

  16. Development of numerical framework to study microstructural effects on shock initiation in heterogeneous energetic materials

    Science.gov (United States)

    Schmidt, Martin; Rai, Nirmal; Udaykumar, H. S.

    2015-06-01

    Heterogeneous energetic materials like plastic bonded explosives (PBX) have very detailed and non-uniform microstructure. The heterogeneity is mainly because of presence of HMX crystals embedded in a polymer binder matrix. Also, manufacturing defects often creates pores and cracks in the material. Shock interaction with these heterogeneities leads to local heated regions known as hot spots. It is widely accepted that these hot spots are predominantly the cause of triggering reaction and eventually ignition in these energetic materials. There are various physical phenomenon through which hot spot can be created such as pore collapse, inter-granular friction in HMX crystals, shock heating of HMX crystals and binder etc. Hence, microstructural heterogeneity can play a vital role for shock initiation in PBX. In the current work, a general framework has been established for performing mesoscale simulations on heterogeneous energetic material. In order to get an accurate representation of the microstructure, image processing algorithms have been employed on XCMT images of PBX microstructure. The image processing framework has been built up with massively parallel Eulerian code, SCIMITAR3D. Shock simulation on PBX microstructures has been performed and the effect of microstructure geometry has been studied for different shock strengths case. The simulation results have been shown to resolve hot spots created due to various heterogeneities present in the microstructure.

  17. Evaluating heterogeneous conservation effects of forest protection in Indonesia.

    Science.gov (United States)

    Shah, Payal; Baylis, Kathy

    2015-01-01

    Establishing legal protection for forest areas is the most common policy used to limit forest loss. This article evaluates the effectiveness of seven Indonesian forest protected areas introduced between 1999 and 2012. Specifically, we explore how the effectiveness of these parks varies over space. Protected areas have mixed success in preserving forest, and it is important for conservationists to understand where they work and where they do not. Observed differences in the estimated treatment effect of protection may be driven by several factors. Indonesia is particularly diverse, with the landscape, forest and forest threats varying greatly from region to region, and this diversity may drive differences in the effectiveness of protected areas in conserving forest. However, the observed variation may also be spurious and arise from differing degrees of bias in the estimated treatment effect over space. In this paper, we use a difference-in-differences approach comparing treated observations and matched controls to estimate the effect of each protected area. We then distinguish the true variation in protected area effectiveness from spurious variation driven by several sources of estimation bias. Based on our most flexible method that allows the data generating process to vary across space, we find that the national average effect of protection preserves an additional 1.1% of forest cover; however the effect of individual parks range from a decrease of 3.4% to an increase of 5.3% and the effect of most parks differ from the national average. Potential biases may affect estimates in two parks, but results consistently show Sebangau National Park is more effective while two parks are substantially less able to protect forest cover than the national average. PMID:26039754

  18. Nonlinear effects of locally heterogeneous hydraulic conductivity fields on regional stream-aquifer exchanges

    Science.gov (United States)

    Zhu, J.; Winter, C. L.; Wang, Z.

    2015-11-01

    Computational experiments are performed to evaluate the effects of locally heterogeneous conductivity fields on regional exchanges of water between stream and aquifer systems in the Middle Heihe River basin (MHRB) of northwestern China. The effects are found to be nonlinear in the sense that simulated discharges from aquifers to streams are systematically lower than discharges produced by a base model parameterized with relatively coarse effective conductivity. A similar, but weaker, effect is observed for stream leakage. The study is organized around three hypotheses: (H1) small-scale spatial variations of conductivity significantly affect regional exchanges of water between streams and aquifers in river basins, (H2) aggregating small-scale heterogeneities into regional effective parameters systematically biases estimates of stream-aquifer exchanges, and (H3) the biases result from slow paths in groundwater flow that emerge due to small-scale heterogeneities. The hypotheses are evaluated by comparing stream-aquifer fluxes produced by the base model to fluxes simulated using realizations of the MHRB characterized by local (grid-scale) heterogeneity. Levels of local heterogeneity are manipulated as control variables by adjusting coefficients of variation. All models are implemented using the MODFLOW (Modular Three-dimensional Finite-difference Groundwater Flow Model) simulation environment, and the PEST (parameter estimation) tool is used to calibrate effective conductivities defined over 16 zones within the MHRB. The effective parameters are also used as expected values to develop lognormally distributed conductivity (K) fields on local grid scales. Stream-aquifer exchanges are simulated with K fields at both scales and then compared. Results show that the effects of small-scale heterogeneities significantly influence exchanges with simulations based on local-scale heterogeneities always producing discharges that are less than those produced by the base model

  19. Scaling Effects of Cr(VI) Reduction Kinetics. The Role of Geochemical Heterogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Li [Pennsylvania State Univ., State College, PA (United States); Li, Li [Pennsylvania State Univ., State College, PA (United States)

    2015-10-22

    The natural subsurface is highly heterogeneous with minerals distributed in different spatial patterns. Fundamental understanding of how mineral spatial distribution patterns regulate sorption process is important for predicting the transport and fate of chemicals. Existing studies about the sorption was carried out in well-mixed batch reactors or uniformly packed columns, with few data available on the effects of spatial heterogeneities. As a result, there is a lack of data and understanding on how spatial heterogeneities control sorption processes. In this project, we aim to understand and develop modeling capabilities to predict the sorption of Cr(VI), an omnipresent contaminant in natural systems due to its natural occurrence and industrial utilization. We systematically examine the role of spatial patterns of illite, a common clay, in determining the extent of transport limitation and scaling effects associated with Cr(VI) sorption capacity and kinetics using column experiments and reactive transport modeling. Our results showed that the sorbed mass and rates can differ by an order of magnitude due to of the illite spatial heterogeneities and transport limitation. With constraints from data, we also developed the capabilities of modeling Cr(VI) in heterogeneous media. The developed model is then utilized to understand the general principles that govern the relationship between sorption and connectivity, a key measure of the spatial pattern characteristics. This correlation can be used to estimate Cr(VI) sorption characteristics in heterogeneous porous media. Insights gained here bridge gaps between laboratory and field application in hydrogeology and geochemical field, and advance predictive understanding of reactive transport processes in the natural heterogeneous subsurface. We believe that these findings will be of interest to a large number of environmental geochemists and engineers, hydrogeologists, and those interested in contaminant fate and transport

  20. Effect of Heterogeneity on Decorrelation Mechanisms in Spiking Neural Networks: A Neuromorphic-Hardware Study

    Science.gov (United States)

    Pfeil, Thomas; Jordan, Jakob; Tetzlaff, Tom; Grübl, Andreas; Schemmel, Johannes; Diesmann, Markus; Meier, Karlheinz

    2016-04-01

    High-level brain function, such as memory, classification, or reasoning, can be realized by means of recurrent networks of simplified model neurons. Analog neuromorphic hardware constitutes a fast and energy-efficient substrate for the implementation of such neural computing architectures in technical applications and neuroscientific research. The functional performance of neural networks is often critically dependent on the level of correlations in the neural activity. In finite networks, correlations are typically inevitable due to shared presynaptic input. Recent theoretical studies have shown that inhibitory feedback, abundant in biological neural networks, can actively suppress these shared-input correlations and thereby enable neurons to fire nearly independently. For networks of spiking neurons, the decorrelating effect of inhibitory feedback has so far been explicitly demonstrated only for homogeneous networks of neurons with linear subthreshold dynamics. Theory, however, suggests that the effect is a general phenomenon, present in any system with sufficient inhibitory feedback, irrespective of the details of the network structure or the neuronal and synaptic properties. Here, we investigate the effect of network heterogeneity on correlations in sparse, random networks of inhibitory neurons with nonlinear, conductance-based synapses. Emulations of these networks on the analog neuromorphic-hardware system Spikey allow us to test the efficiency of decorrelation by inhibitory feedback in the presence of hardware-specific heterogeneities. The configurability of the hardware substrate enables us to modulate the extent of heterogeneity in a systematic manner. We selectively study the effects of shared input and recurrent connections on correlations in membrane potentials and spike trains. Our results confirm that shared-input correlations are actively suppressed by inhibitory feedback also in highly heterogeneous networks exhibiting broad, heavy-tailed firing

  1. Neighbourhood Effects, Preference Heterogeneity and Immigrant Educational Attainment

    OpenAIRE

    Cardak, Buly/A; James Ted McDonald

    2002-01-01

    This paper investigates differences between the educational attainment immigrants and native born individuals in Australia by using Australian Youth Survey (AYS) data combined with aggregate Australian Census data. We decompose differences in educational attainment into: (i) typical demographic and socio-economic sources common to all ethnic groups, (ii) unobserved region of residence and region of origin effects, and (iii) neighbourhood effects such as degree and ethnic concentration of part...

  2. Effect of heterogeneous catalysts on radiolysis of aqueous solutions of phenol

    International Nuclear Information System (INIS)

    Peculiarities of phenol aqueous solution radiolysis under conditions of continuous liquid flow through the layer of solid sorbent or various heterogeneous catalysts (MnO2, Pt, Ni, Ni-Pd), applied on activated carbons, are investigated. γ-radiation dose rate is 3 Gy/s, the dose is 0.36 kGy. Data on radiation-chemical yields of phenol destruction in the presence of sorbent and heterogeneous catalysts are presented. It is shown that during heterogeneous radiolysis of phenol in all the cases its more effective removal as compared with homogeneous one takes place; simultaneously, selective effect of the surface nature of the catalysts used on the mechanism of reactions and quantitative characteristics of the destruction process is observed

  3. The effect of ignoring individual heterogeneity in Weibull log-normal sire frailty models

    DEFF Research Database (Denmark)

    Damgaard, Lars Holm; Korsgaard, Inge Riis; Simonsen, J;

    2006-01-01

    The objective of this study was, by means of simulation, to quantify the effect of ignoring individual heterogeneity in Weibull sire frailty models on parameter estimates and to address the consequences for genetic inferences. Three simulation studies were evaluated, which included 3 levels of...... sire model, equivalent to the animal model used to generate the data (complete sire model), and a corresponding model in which individual heterogeneity in log-frailty was neglected (incomplete sire model). Parameter estimates were obtained from a Bayesian analysis using Gibbs sampling, and also from...... the software Survival Kit for the incomplete sire model. For the incomplete sire model, the Monte Carlo and Survival Kit parameter estimates were similar. This study established that when unobserved individual heterogeneity was ignored, the parameter estimates that included sire effects were biased...

  4. Changes in porosity, permeability and surface area during rock dissolution: effects of mineralogical heterogeneity

    CERN Document Server

    Min, Ting; Chen, Li; Kang, Qinjun; Tao, Wen-Quan

    2015-01-01

    Effects of heterogeneity of mineral distribution and reaction rate on the rock dissolution process are investigated using a pore-scale reactive transport model based on the lattice Boltzmann method. Coupled fluid flow, species transport, chemical reaction and solid structure alternation due to dissolution are simulated. Effects of mineral distributions and chemical heterogeneity on the dissolution behaviors and evolutions of hydrologic properties are studied under different reactive transport conditions. Simulation results show that the coupling between advection, diffusion and reaction as well as the mineralogical heterogeneity leads to complex reactive transport behaviors and complicated temporal evolutions of hydrologic properties including porosity, permeability and reactive surface. Diverse relationships between surface area and volume are predicted, which cannot be described by simple models such as the spherical-grain model. Porosity-permeability relationships also differ under different mineral distri...

  5. Effective Data Acquisition Protocol for Multi-Hop Heterogeneous Wireless Sensor Networks Using Compressive Sensing

    Directory of Open Access Journals (Sweden)

    Ahmed M. Khedr

    2015-10-01

    Full Text Available In designing wireless sensor networks (WSNs, it is important to reduce energy dissipation and prolong network lifetime. Clustering of nodes is one of the most effective approaches for conserving energy in WSNs. Cluster formation protocols generally consider the heterogeneity of sensor nodes in terms of energy difference of nodes but ignore the different transmission ranges of them. In this paper, we propose an effective data acquisition clustered protocol using compressive sensing (EDACP-CS for heterogeneous WSNs that aims to conserve the energy of sensor nodes in the presence of energy and transmission range heterogeneity. In EDACP-CS, cluster heads are selected based on the distance from the base station and sensor residual energy. Simulation results show that our protocol offers a much better performance than the existing protocols in terms of energy consumption, stability, network lifetime, and throughput.

  6. Quantifying effects of soil heterogeneity on groundwater pollution at four sites in USA

    Institute of Scientific and Technical Information of China (English)

    Saskia; Vuurens; Frank; Stagnitti; Gerrit; de; Rooij; Jan

    2005-01-01

    Four sites located in the north-eastern region of the United States of America have been chosen to investigate the impacts of soil heterogeneity in the transport of solutes (bromide and chloride) through the vadose zone (the zone in the soil that lies below the root zone and above the permanent saturated groundwater). A recently proposed mathematical model based on the cumulative beta distribution has been deployed to compare and contrast the regions' heterogeneity from multiple sample percolation experiments. Significant differences in patterns of solute leaching were observed even over a small spatial scale, indicating that traditional sampling methods for solute transport, for example the gravity pan or suction lysimeters, or more recent inventions such as the multiple sample percolation systems may not be effective in estimating solute fluxes in soils when a significant degree of soil heterogeneity is present. Consequently, ignoring soil heterogeneity in solute transport studies will likely result in under- or overprediction of leached fluxes and potentially lead to serious pollution of soils and/or groundwater.The cumulative beta distribution technique is found to be a versatile and simple technique of gaining valuable information regarding soil heterogeneity effects on solute transport. It is also an excellent tool for guiding future decisions of experimental designs particularly in regard to the number of samples within one site and the number of sampling locations between sites required to obtain a representative estimate of field solute or drainage flux.

  7. The effect of material heterogeneity in curved composite beams for use in aircraft structures

    Science.gov (United States)

    Otoole, Brendan J.; Santare, Michael H.

    1992-01-01

    A design tool is presented for predicting the effect of material heterogeneity on the performance of curved composite beams for use in aircraft fuselage structures. Material heterogeneity can be induced during processes such as sheet forming and stretch forming of thermoplastic composites. This heterogeneity can be introduced in the form of fiber realignment and spreading during the manufacturing process causing a gradient in material properties in both the radial and tangential directions. The analysis procedure uses a separate two-dimensional elasticity solution for the stresses in the flanges and web sections of the beam. The separate solutions are coupled by requiring the forces and displacements match at the section boundaries. Analysis is performed for curved beams loaded in pure bending and uniform pressure. The beams can be of any general cross-section such as a hat, T-, I-, or J-beam. Preliminary results show that geometry of the beam dictates the effect of heterogeneity on performance. Heterogeneity plays a much larger role in beams with a small average radius to depth ratio, R/t, where R is the average radius of the beam and t is the difference between the inside and outside radius. Results of the analysis are in the form of stresses and displacements, and they are compared to both mechanics of materials and numerical solutions obtained using finite element analysis.

  8. Bubble Effect in Heterogeneous Nuclear Fuel Solution System

    Institute of Scientific and Technical Information of China (English)

    ZHOU; Xiao-ping; LUO; Huang-da; ZHANG; Wei; ZHU; Qing-fu

    2013-01-01

    Bubble effect means system reactivity changes due to the bubble induced solution volume,neutron leakage and absorption properties,neutron energy spectrum change in the nuclear fuel solution system.In the spent fuel dissolver,during uranium element shearing,the oxygen will be inlet to accelerate the

  9. Negative cooperativity in Root-effect hemoglobins: role of heterogeneity.

    Science.gov (United States)

    Decker, Heinz; Nadja, Hellmann

    2007-10-01

    In some animals, the oxygen transport capacity of blood decreases when pH is lowered, yielding oxygen binding curves with Hill-coefficients smaller than unity. This so-called Root effect is observed in several fishes and is important for creating large oxygen partial pressures locally, for example in the swim bladder. While there is general agreement on the physiological advantages of this effect, its molecular basis remains ambiguous. Various studies show that isoforms of hemoglobins usually are present in the hemolymph, when the Root effect is observed. Here, we show that in such a case the mixture of these isoforms can exhibit apparent negative cooperativity, although each component taken separately can be described by the MWC model. In other cases, isolated isoforms exhibit true negative cooperativity. The well established MWC model describes many cooperative phenomena of enzymes and respiratory proteins but is not capable of describing negative cooperativity. In order to model negative cooperativity within a single molecular species a decoupling model might be employed, as pointed out previously. However, simulations show that it is not mandatory to have species with negative cooperativity, in order to obtain the binding curves typically seen for whole blood. These two aspects of the Root effect will be discussed on the basis of data from the literature. PMID:21672870

  10. Effects of Incorporated Radioactivity and External Radiation on Heterogeneous Catalysis

    International Nuclear Information System (INIS)

    The vapour phase dehydration of cyclohexanol on magnesium sulphate and magnesium sulphatesodium sulphate catalysts and the dehydrogenation of methylcyclohexane to toluene on promoted chromiaalumina catalysts were studied in flow systems. The effects of incorporating radioisotopes into the catalysts and of pre-irradiation with cobalt-60 gamma rays were investigated. Magnesium sulphate and magnesium sulphate-sodium sulphate catalysts containing up to 45.5 mc (S35)/g were less active than non-radioactive catalysts of similar composition when compared on a unit surface area basis. The reduction in catalytic activity persisted even after the radioactivity had substantially decayed. Further, no change in catalytic activity was observed upon irradiation with X-rays while the reaction was in progress. From these results it is concluded that the emission of beta particles from the catalyst during its use has no effect. Reports of an enhancement of catalytic activity may be attributed to the fact that,for a given set of preparation conditions, the radioactive catalysts have larger surface areas than their non-radioactive counterparts, and that this was not taken into account. Pre-irradiation with cobalt-60 gamma rays to 1011 erg/g had no effect on the catalysts' activity. In contrast, pre-irradiation of the chromia-alumina catalysts with cobalt-60 gamma rays to a dose of 4.2 x 1011 erg/g enhanced the catalytic activity by about 34% at 485oC, but incorporation of up to 148 mc (Pm147)/g of catalyst had little or no effect. No substantial effect of radiation on surface area or on apparent activation energy was observed in this case. (author)

  11. Multidetector computed tomography evaluation of bony fragments and donor sites in acute patellar dislocation

    Energy Technology Data Exchange (ETDEWEB)

    Peltola, Erno K.; Koskinen, Seppo K. (Dept. of Radiology, Helsinki Medical Imaging Center, Helsinki Univ. Hospital, Toeoeloe Trauma Center, Helsinki (Finland)), e-mail: erno.peltola@fimnet.fi

    2011-02-15

    Background: Patellar dislocation is frequently associated with bony fragments that are difficult to see on radiographs. MRI or MDCT are often used to rule out or characterize these bony fragments. Purpose: To assess the use of MDCT for locating bony fragments and donor sites in patients with acute patellar dislocation, and to test whether sizes and quantity of bony fragments differ between first-time dislocations and recurrent dislocations. Material and Methods: Retrospective data from two hospitals during a 96-month period were collected, and a total of 46 patients (mean age 27 years, range 9-69 years) that had sustained an acute patellar dislocation (22 first-time, 24 recurrent) were identified. Size, location and donor site of bony fragments were evaluated on MDCT images. Surgical correlation was available for 22 of 46 patients. Results: On MDCT images, the likely donor site could be identified in 62 of 71 (87%) bony fragments. Of the bony fragments that were seen on MDCT images, 40 of 68 (59%) were not seen on AP and lateral views of the conventional radiographs. There was no significant difference in size of bony fragments between first-time or recurrent dislocators (p 0.77). The average number of bony fragments were 2.1 and 1.0 in first-time and recurrent dislocators, respectively. The location and donor site of bony fragments was similar between two patients groups. Conclusion: MDCT is a suitable imaging method to locate bony fragments and donor sites. The number of bony fragments seems to be higher in first-time dislocators than recurrent dislocators, otherwise findings between the two patient groups were similar

  12. Heterogeneous responses to effective tax enforcement: evidence from Spanish firms

    OpenAIRE

    Almunia, Miguel; Lopez-Rodriguez, David

    2014-01-01

    This paper investigates the effects of monitoring the information trails generated by firms’ activities in order to improve tax compliance. We use quasi-experimental variation provided by a Large Taxpayers Unit (LTU) in Spain to empirically test the theoretical predictions on firms’ responses to an increase in monitoring effort. Firms with more than €6 million in reported revenue are monitored by the LTU, which devotes more resources to verifying the transactions reported by those firms. U...

  13. Generalized traveling wave in heterogeneous media: Allee effect can inhibit invasion

    OpenAIRE

    Sarels, Benoit

    2012-01-01

    In this paper, we study a simple one-dimensional model of reaction-diffusion with bistable non-linearity and in heterogeneous media. The bistable term accounts for the so-called Allee effect, and the heterogeneity in the media is localized. We recall the definition of a transition wave used in similar situations by well-known authors, and propose an alternative definition for discussion. We call it generalized traveling wave. As a consequence, we give new results of pinning in such media, due...

  14. The heterogeneous world of congruency sequence effects: an update.

    Science.gov (United States)

    Duthoo, Wout; Abrahamse, Elger L; Braem, Senne; Boehler, Carsten N; Notebaert, Wim

    2014-01-01

    Congruency sequence effects (CSEs) refer to the observation that congruency effects in conflict tasks are typically smaller following incongruent compared to following congruent trials. This measure has long been thought to provide a unique window into top-down attentional adjustments and their underlying brain mechanisms. According to the renowned conflict monitoring theory, CSEs reflect enhanced selective attention following conflict detection. Still, alternative accounts suggested that bottom-up associative learning suffices to explain the pattern of reaction times and error rates. A couple of years ago, a review by Egner (2007) pitted these two rivalry accounts against each other, concluding that both conflict adaptation and feature integration contribute to the CSE. Since then, a wealth of studies has further debated this issue, and two additional accounts have been proposed, offering intriguing alternative explanations. Contingency learning accounts put forward that predictive relationships between stimuli and responses drive the CSE, whereas the repetition expectancy hypothesis suggests that top-down, expectancy-driven control adjustments affect the CSE. In the present paper, we build further on the previous review (Egner, 2007) by summarizing and integrating recent behavioral and neurophysiological studies on the CSE. In doing so, we evaluate the relative contribution and theoretical value of the different attentional and memory-based accounts. Moreover, we review how all of these influences can be experimentally isolated, and discuss designs and procedures that can critically judge between them. PMID:25250005

  15. The heterogeneous world of congruency sequence effects: An update.

    Directory of Open Access Journals (Sweden)

    WoutDuthoo

    2014-09-01

    Full Text Available Congruency sequence effects (CSEs refer to the observation that congruency effects in conflict tasks are typically smaller following incongruent compared to following congruent trials. This measure has long been thought to provide a unique window into top-down attentional adjustments and their underlying brain mechanisms. According to the renowned conflict monitoring theory, CSEs reflect enhanced selective attention following conflict detection. Still, alternative accounts suggested that bottom-up associative learning suffices to explain the pattern of reaction times and error rates. A couple of years ago, a review by Egner (2007 pitted these two rivalry accounts against each other, concluding that both conflict adaptation and feature integration contribute to the CSE. Since then, a wealth of studies has further debated this issue, and two additional accounts have been proposed, offering intriguing alternative explanations. Contingency learning accounts put forward that predictive relationships between stimuli and responses drive the CSE, whereas the repetition expectancy hypothesis suggests that top-down, expectancy-driven control adjustments affect the CSE. In the present paper, we build further on the previous review (Egner, 2007 by summarizing and integrating recent behavioural and neurophysiological studies on the CSE. In doing so, we evaluate the relative contribution and theoretical value of the different attentional and memory-based accounts. Moreover, we review how all of these influences can be experimentally isolated, and discuss designs and procedures that can critically judge between them.

  16. Explaining heterogeneity in disability with major depressive disorder : Effects of personal and environmental characteristics

    NARCIS (Netherlands)

    Verboom, C.E.; Sentse, M.; Sijtsema, J.J.; Nolen, W.A.; Ormel, J.; Penninx, B.W.

    2011-01-01

    Background: Major depressive disorder (MDD) is associated with disability, yet some patients function surprisingly well. The reason for this heterogeneity between patients is unclear. Building on the International Classification of Functioning (ICE) model, this study aims to examine effects of perso

  17. Pore-Scale Process Coupling and Effective Surface Reaction Rates in Heterogeneous Subsurface Materials

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chongxuan; Liu, Yuanyuan; Kerisit, Sebastien N.; Zachara, John M.

    2015-09-01

    This manuscript provides a review of pore-scale researches in literature including experimental and numerical approaches, and scale-dependent behavior of geochemical and biogeochemical reaction rates in heterogeneous porous media. A mathematical equation that can be used to predict the scale-dependent behavior of geochemical reaction rates in heterogeneous porous media has been derived. The derived effective rate expression explicitly links the effective reaction rate constant to the intrinsic rate constant, and to the pore-scale variations in reactant concentrations in porous media. Molecular simulations to calculate the intrinsic rate constants were provided. A few examples of pore-scale simulations were used to demonstrate the application of the equation to calculate effective rate constants in heterogeneous materials. The results indicate that the deviation of effective rate constant from the intrinsic rate in heterogeneous porous media is caused by the pore-scale distributions of reactants and their correlation, which are affected by the pore-scale coupling of reactions and transport.

  18. Oxalic acid as a heterogeneous ice nucleus in the upper troposphere and its indirect aerosol effect

    Directory of Open Access Journals (Sweden)

    B. Zobrist

    2006-05-01

    Full Text Available Heterogeneous ice freezing points of aqueous solutions containing various immersed solid dicarboxylic acids (oxalic, adipic, succinic, phthalic and fumaric have been measured with a differential scanning calorimeter. The results show that only the dihydrate of oxalic acid (OAD acts as a heterogeneous ice nucleus, with an increase in freezing temperature between 2-5 K depending on solution composition. In several field campaigns, oxalic acid enriched particles have been detected in the upper troposphere with single particle aerosol mass spectrometry. Simulations with a microphysical box model indicate that the presence of OAD may reduce the ice particle number density in cirrus clouds by up to ~50% when compared to exclusively homogeneous cirrus formation without OAD. Using the ECHAM4 climate model we estimate the global net radiative effect caused by this heterogeneous freezing to result in a cooling as high as -0.3 Wm-2.

  19. Oxalic acid as a heterogeneous ice nucleus in the upper troposphere and its indirect aerosol effect

    Directory of Open Access Journals (Sweden)

    B. Zobrist

    2006-01-01

    Full Text Available Heterogeneous ice freezing points of aqueous solutions containing various immersed solid dicarboxylic acids (oxalic, adipic, succinic, phthalic and fumaric have been measured with a differential scanning calorimeter. The results show that only the dihydrate of oxalic acid (OAD acts as a heterogeneous ice nucleus, with an increase in freezing temperature between 2 and 5 K depending on solution composition. In several field campaigns, oxalic acid enriched particles have been detected in the upper troposphere with single particle aerosol mass spectrometry. Simulations with a microphysical box model indicate that the presence of OAD may reduce the ice particle number density in cirrus clouds by up to ~50% when compared to exclusively homogeneous cirrus formation without OAD. Using the ECHAM4 climate model we estimate the global net radiative effect caused by this heterogeneous freezing to result in a cooling as high as −0.3 Wm−2.

  20. Effects of Spatial Heterogeneity in Rainfall and Vegetation Type on Soil Moisture and Evapotranspiration

    CERN Document Server

    Puma, Michael J; Rodriguez-Iturbe, Ignacio; Nordbotten, Jan M; Guswa, Andrew J; Kavetski, Dmitri

    2016-01-01

    Nonlinear plant-scale interactions controlling the soil-water balance are generally not valid at larger spatial scales due to spatial heterogeneity in rainfall and vegetation type. The relationships between spatially averaged variables are hysteretic even when unique relationships are imposed at the plant scale. The characteristics of these hysteretic relationships depend on the size of the averaging area and the spatial properties of the soil, vegetation, and rainfall. We upscale the plant-scale relationships to the scale of a regional land-surface model based on simulation data obtained through explicit representation of spatial heterogeneity in rainfall and vegetation type. The proposed upscaled function improves predictions of spatially averaged soil moisture and evapotranspiration relative to the effective-parameter approach for a water-limited Texas shrubland. The degree of improvement is a function of the scales of heterogeneity and the size of the averaging area. We also find that single-valued functi...

  1. Macroscopic heterogeneity effects in FeNiNbCuBSi ribbons

    International Nuclear Information System (INIS)

    The effect of Ni substitution on the magnetic response to macroscopic heterogeneity has been investigated on (FeNi)73.5Nb3Cu1B9Si13.5 ribbons. 10, 20 and 30 at% of Ni was alloyed to the detriment of Fe. No significant change was observed as to the bias to build heterogeneity in a non-protective annealing ambience. Instead, the favorable insensitivity of magnetic properties to the heterogeneity, as known for the standard Finemet, gets lost with Ni substitution and serious magnetic hardening takes place for higher Ni percentage. These changes are mainly due to the changed intrinsic properties of the Ni-substituted alloys, as high magnetostriction and the occurrence of a Ni-containing phase, if the alloy is nanocrystallized

  2. Heterogeneous photocatalytic degradation of rose bengal: Effect of operational parameters

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Japinder, E-mail: jap.chawla@gmail.com; Singhal, Sonal, E-mail: sonal1174@gmail.com

    2014-10-01

    The photocatalytic degradation of rose bengal dye has been investigated using ZnO nanoparticles as photocatalyst. ZnO nanoparticles were found to be efficient catalyst for the degradation of dye and 98% degradation was observed in 90 min. Effect of various operational parameters such as amount of catalyst (0.25–2.00 g/L), concentration of dye (0.01–0.05 mM) and pH (3–11) of dye solution on the rate of dye degradation was studied. The most favorable results for the degradation of rose bengal were observed at pH 5 at a catalyst loading of 1 g/L. Moreover, hydroxyl radicals have been detected in the photocatalytic reaction mixture by using terephthalic acid photoluminescence probing technique. The reusability of the catalyst has also been studied and catalyst was found to be active even after being used for 5 times.

  3. Bony injuries in trauma patients diagnosed by radiological examination

    International Nuclear Information System (INIS)

    This study was carried out to determine the incidence of bony injuries in trauma patients who had plain radiographs done at the Central Regional Hospital in Cape Coast. This is a retrospective study based on plain radiographs taken by trauma patients who reported to the Central Regional Hospital. The case notes of all patients with a discharge diagnosis of Road Traffic Accident or trauma of all aetiologies that presented to the hospital between January 2005 and December 2011 were retrieved, and those patients that had skeletal radiographic examinations were included in this study. The total number of cases seen was 1,133. The ages of the patients ranged between 1 and 72 years. Sixty-nine (6.1%) of the patients were between 1 and 4 years old, with the majority between 20 and 49 years old, constituting 52.3%, with patients 60 years and above at 9.2%. There was statistically significant difference between male and female patients (p=0.001). A total of 912 (80.5%) patients had radiographic examination done out of which only 324 (35.5%) radiographs could be retrieved. There were 106 (32.7%) radiographs with various bony injuries which was statistically significant (p=0.001). Rib fractures represented 19/106 (17.9%) of which 62.5% had multiple rib fractures. Fifty-eight (54.7%) had long bone fractures. Other anatomical sites included the pelvis and the skull. Conclusion: Trauma is a major public health problem in the country, involving mainly the productive age group. Unnecessary exposure to X-rays is common. Inadequate management of trauma patients negatively impacts on the outcome of trauma patients. Trauma prevention is the best way forward.(au)

  4. Effects of heterogeneity on earthquake location at ISC

    Science.gov (United States)

    Adams, R. D.

    1992-12-01

    Earthquake location at the International Seismological Centre is carried out by routine least-squares analysis using Jeffreys-Bullen travel times. It is impossible to examine every earthquake in detail, but when obvious discrepancies in location become apparent, adjustments can be made by analysts, usually in phase identification or the restraint of depth. Such discrepancies often result from inappropriateness of the Jeffreys-Bullen model. The effect is most apparent in subduction zones, where it is often difficult to reconcile local and teleseismic observations, and differences from the standard model can result in substantial mislocations. Large events, located by steeply descending teleseismic phases, may be only slightly misplaced, with large residuals at close stations giving a true indication of velocity anomalies. Small events, however, are often significantly misplaced, although giving small residuals at a few close stations. These apparently well located events give compensating misinformation about velocities and location. In other areas, especially mid-oceanic ridges, difficulties in depth determination are likely to be related to deviations from a laterally homogeneous velocity model.

  5. NOx AND HETEROGENEITY EFFECTS IN HIGH LEVEL WASTE (HLW)

    International Nuclear Information System (INIS)

    We summarize contributions from our EMSP supported research to several field operations of the Office of Environmental Management (EM). In particular we emphasize its impact on safety programs at the Hanford and other EM sites where storage, maintenance and handling of HLW is a major mission. In recent years we were engaged in coordinated efforts to understand the chemistry initiated by radiation in HLW. Three projects of the EMSP (''The NOx System in Nuclear Waste,'' ''Mechanisms and Kinetics of Organic Aging in High Level Nuclear Wastes, D. Camaioni--PI'' and ''Interfacial Radiolysis Effects in Tanks Waste, T. Orlando--PI'') were involved in that effort, which included a team at Argonne, later moved to the University of Notre Dame, and two teams at the Pacific Northwest National Laboratory. Much effort was invested in integrating the results of the scientific studies into the engineering operations via coordination meetings and participation in various stages of the resolution of some of the outstanding safety issues at the sites. However, in this Abstract we summarize the effort at Notre Dame

  6. Effect of heterogeneities on the thermoelectric power of pressure vessel steel

    International Nuclear Information System (INIS)

    In service working conditions, the vessel of the Pressurized Water Reactors (PWR) undergoes an ageing due to irradiation. In order to follow the evolution of the mechanical characteristics of the steel in service, EDF launched a surveillance program which consists to carry out mechanical tests on samples aged in reactor. However, the results of these tests have the disadvantage to be affected by the presence of heterogeneities within the steel. Indeed, because of its manufacturing process, the steel contains segregated areas. Thus, EDF launched Thermoelectric Power Measurements (TEP) on the resilience samples of the surveillance program, to complete the mechanical tests and to help with their interpretation. However, these measurements are today difficult to analyse because they include at the same time the effect of the irradiation and the effect of the metallurgical heterogeneities. The aim of this work consisted in evaluating the effect of the heterogeneities on the TEP of the non-irradiated vessel steel. For that, a numerical model was developed which allows to calculate the TEP of a composite structure. We have shown that the model is pertinent to highlight the effect of the heterogeneities on the TEP of the vessel steel, which is considered like a 'matrix'/'segregation' composite. The model allowed us to put emphasis on the influence of different parameters on the TEP measurement. We have thus showed that the measurements conditions have an important effect on the obtained TEP value (influence of the applied pressure, the position of the sample on the device, the site of the metallurgical heterogeneities,...). (author)

  7. Analysis of the effect of short interval staged bilateral replacement in the treatment of ankylosing spondylitis combined with bilateral hip bony ankylosis%短间隔分期双侧置换治疗强直性脊柱炎伴双髋关节骨性强直的疗效分析

    Institute of Scientific and Technical Information of China (English)

    韩博闻; 殷力; 韩奇财; 娄超举; 李弘帅; 胡明鑫

    2015-01-01

    Objective To discuss the clinical effects of short interval staged bilateral replacement in the treatment of ankylo-sing spondylitis(AS)combined with bilateral hip bony ankylosis. Methods 21 cases(42 hips)of ankylosing spondylitis com-bined with bilateral hip bony ankylosis hospitalized from October of 2010 to October of 2014 were enrolled and received short in-terval(bilateral operation interval < 1 month)staged bilateral total hip arthroplasty. The Harris score,visual analogue score (VAS),total hip joint activity,short form health survey(SF - 36)were compared between pre - operation and the last follow -up,and the postoperative complications were observed. Results The Harris score,total hip joint activity and SF - 36 score on the last follow - up day were markedly increased than those before operation. The VAS score of the last follow - up day were markedly decreased than those before operation. 6 hips had mild heterotopic ossification,and 3 hips had femoral anterolateral in-termittent pain,but those had no obvious effect on the function. There were no femoral nerve injury. Conclusion SISBTHA can reconstruct the hip joint function,improve the quality of life,which is an effective and reliable method.%目的:探讨短间隔分期双侧置换治疗强直性脊柱炎(ankylosing spondylitis,AS)伴双髋关节骨性强直的临床疗效。方法回顾性研究2010年10月至2014年10月收治的21例(42髋)强直性脊柱炎双髋关节骨性强直患者,采用短间隔(双侧手术间隔<1个月)分期双侧人工全髋关节置换术(short interval staged bilateraltotal hip arthroplasty,SISBTHA)。比较患者术前及末次随访的 Harris 评分、疼痛视觉模拟评分(VAS)、髋关节总活动度、健康调查简表(SF -36),以及观察术后并发症发生情况。结果末次随访时 Harris 评分、髋关节总体活动度和 SF -36评分均较术前显著升高(P <0.05),VAS 评分较术前显著降低(P <0

  8. "Macroeconomic stabilization in a heterogeneous monetary union: some insights into the effects of fiscal policy coordination"

    OpenAIRE

    Cornel Oros

    2008-01-01

    This paper studies the effects the fiscal coordination can have in terms of macroeconomic stabilization in a monetary Union which is heterogeneous at the level of the mechanisms of monetary policy transmission. We will use a static Keynesian model in a closed monetary Union and will prove that the stabilization effectiveness depends mainly on the type and origin of the economic shocks affecting the Union members (demand or supply shocks, domestic or foreign shocks) and on the extent of the Un...

  9. Heterogeneous Aid Effects on Tax Revenues: Accounting for Government Stability in WAEMU Countries

    OpenAIRE

    YOHOU, Djedje Hermann; Goujon, Michaël; OUATTARA, Wautabouna

    2015-01-01

    We examine the heterogeneous effects due to government stability of foreign aid on tax revenues in the West African Economic and Monetary Union countries over the period 1986-2010. We show that the tax effects of aid are gradual and varying across countries according to the level of government stability. The Panel Smooth Threshold Regressions indicate that at low levels of government stability, aid negatively affects tax performances. At high levels, it encourages tax collection. Consequently...

  10. Fiscal policy effects in a heterogeneous-agent OLG economy with an aging population

    OpenAIRE

    Nishiyama, Shinichi

    2015-01-01

    This paper incorporates the aging population projected by the U.S. Social Security Administration to a heterogeneous-agent OLG model with idiosyncratic wage shocks and analyzes its effects on individual households, the government budget, and the overall economy. The fiscal gap caused by the demographic change is 2.92% of GDP under the SSA's intermediate projection. The effect of the aging population is large by itself and depends significantly on how the government finances the cost of the de...

  11. On the validity of effective formulations for transport through heterogeneous porous media

    Science.gov (United States)

    de Dreuzy, Jean-Raynald; Carrera, Jesus

    2016-04-01

    Geological heterogeneity enhances spreading of solutes and causes transport to be anomalous (i.e., non-Fickian), with much less mixing than suggested by dispersion. This implies that modeling transport requires adopting either stochastic approaches that model heterogeneity explicitly or effective transport formulations that acknowledge the effects of heterogeneity. A number of such formulations have been developed and tested as upscaled representations of enhanced spreading. However, their ability to represent mixing has not been formally tested, which is required for proper reproduction of chemical reactions and which motivates our work. We propose that, for an effective transport formulation to be considered a valid representation of transport through heterogeneous porous media (HPM), it should honor mean advection, mixing and spreading. It should also be flexible enough to be applicable to real problems. We test the capacity of the multi-rate mass transfer (MRMT) model to reproduce mixing observed in HPM, as represented by the classical multi-Gaussian log-permeability field with a Gaussian correlation pattern. Non-dispersive mixing comes from heterogeneity structures in the concentration fields that are not captured by macrodispersion. These fine structures limit mixing initially, but eventually enhance it. Numerical results show that, relative to HPM, MRMT models display a much stronger memory of initial conditions on mixing than on dispersion because of the sensitivity of the mixing state to the actual values of concentration. Because MRMT does not restitute the local concentration structures, it induces smaller non-dispersive mixing than HPM. However long-lived trapping in the immobile zones may sustain the deviation from dispersive mixing over much longer times. While spreading can be well captured by MRMT models, in general non-dispersive mixing cannot.

  12. On the validity of effective formulations for transport through heterogeneous porous media

    Directory of Open Access Journals (Sweden)

    J.-R. de Dreuzy

    2015-11-01

    Full Text Available Geological heterogeneity enhances spreading of solutes, and causes transport to be anomalous (i.e., non-Fickian, with much less mixing than suggested by dispersion. This implies that modeling transport requires adopting either stochastic approaches that model heterogeneity explicitly or effective transport formulations that acknowledge the effects of heterogeneity. A number of such formulations have been developed and tested as upscaled representations of enhanced spreading. However, their ability to represent mixing has not been formally tested, which is required for proper reproduction of chemical reactions and which motivates our work. We propose that, for an effective transport formulation to be considered a valid representation of transport through Heterogeneous Porous Media (HPM, it should honor mean advection, mixing and spreading. It should also be flexible enough to be applicable to real problems. We test the capacity of the Multi-Rate Mass Transfer (MRMT to reproduce mixing observed in HPM, as represented by the classical multi-Gaussian log-permeability field with a Gaussian correlation pattern. Non-dispersive mixing comes from heterogeneity structures in the concentration fields that are not captured by macrodispersion. These fine structures limit mixing initially, but eventually enhance it. Numerical results show that, relative to HPM, MRMT models display a much stronger memory of initial conditions on mixing than on dispersion because of the sensitivity of the mixing state to the actual values of concentration. Because MRMT does not restitute the local concentration structures, it induces smaller non-dispersive mixing than HPM. However long-lived trapping in the immobile zones may sustain the deviation from dispersive mixing over much longer times. While spreading can be well captured by MRMT models, non-dispersive mixing cannot.

  13. Radiographic Study on the Bony Changes of Mandibular Condyle Head in Temporomandibular Disorder Patients

    International Nuclear Information System (INIS)

    The author has studied radiographic bony changes of mandibular condyle head in temporomandibular disorder patients using Oblique lateral transcranial projection, Orthopantomography, and Tomography. The bony change types and the frequencies of occurrence and the incidences of bony changes in three different radiographic techniques were examined. The coincidences of body change types between the Oblique lateral transcranial projection and the lateral part of Tomogram, the Orthopantomogram and the medial part of Tomogram were also examined. The results were as follows: 1. The mean age of patients was 31.7 years and under 40 years were 24 patients, women were 27 patients, men were 4 patients. 2. The observable cases of bony changes in all three radiographic techniques were 19 cases (50%) of 38 cases and the observable cases of bony changes in only Tomography were 5 cases (13.2%). 3. The most frequent radiographic bony change type was osteophyte and next orders were flattening, erosion, concavity. 4. The positional incidences of bony changes in Tomogram were 31 cases in lateral part and 27 cases in central part. 5. The coincidence of bony change types between the oblique lateral transcranial projection and the lateral part of Tomogram was 80%, and the coincidence between the Orthopantomogram and the medial part of Tomogram was 76.9%.

  14. Quantitative computed tomography as a test of endurance for evaluation of bony plates

    International Nuclear Information System (INIS)

    Quantitative computed tomography was used to determine the radiodensity of bony plates. The CT scans provided information regarding radiodensity of bony plates and allowed to verify the uniformity of bone mineral density in their scope. The proposed methodology should be considered as another tool for determining the resistance of these biomaterials. (author)

  15. Experimental study on effects of geologic heterogeneity in enhancing dissolution trapping of supercritical CO2

    Science.gov (United States)

    Agartan, Elif; Trevisan, Luca; Cihan, Abdullah; Birkholzer, Jens; Zhou, Quanlin; Illangasekare, Tissa H.

    2015-03-01

    Dissolution trapping is one of the primary mechanisms that enhance the storage security of supercritical carbon dioxide (scCO2) in saline geologic formations. When scCO2 dissolves in formation brine produces an aqueous solution that is denser than formation brine, which leads to convective mixing driven by gravitational instabilities. Convective mixing can enhance the dissolution of CO2 and thus it can contribute to stable trapping of dissolved CO2. However, in the presence of geologic heterogeneities, diffusive mixing may also contribute to dissolution trapping. The effects of heterogeneity on mixing and its contribution to stable trapping are not well understood. The goal of this experimental study is to investigate the effects of geologic heterogeneity on mixing and stable trapping of dissolved CO2. Homogeneous and heterogeneous media experiments were conducted in a two-dimensional test tank with various packing configurations using surrogates for scCO2 (water) and brine (propylene glycol) under ambient pressure and temperature conditions. The results show that the density-driven flow in heterogeneous formations may not always cause significant convective mixing especially in layered systems containing low-permeability zones. In homogeneous formations, density-driven fingering enhances both storage in the deeper parts of the formation and contact between the host rock and dissolved CO2 for the potential mineralization. On the other hand, for layered systems, dissolved CO2 becomes immobilized in low-permeability zones with low-diffusion rates, which reduces the risk of leakage through any fault or fracture. Both cases contribute to the permanence of the dissolved plume in the formation.

  16. Study on morphology of subacromial bony spur using three-dimensional computed tomography

    International Nuclear Information System (INIS)

    Arthroscopic subacromial decompression (ASD) is a procedure required for rotator cuff tears and impingement syndrome, but the amount of bone to be removed and range of decompression depend on the surgery performed. We reviewed the morphology of bony spur using three-dimensional computed tomography (3DCT). The subjects were 27 cases operated on for rotator cuff tears from October 2008 to July 2009. We took CT images of all cases preoperatively. We classified the morphology of bony spurs into four groups according to size and investigated the characteristics. The bony spur was found to elongate to the coracoid process and show double floor-like configuration inwards. Moreover, when the bony spur size increases, the duration of the disease also increases. In addition, there was a tendency for the size of rotator cuff tears to grow large except in trauma cases. 3DCT can capture the morphological characteristics of subacromial bony spurs and provide useful information in ASD. (author)

  17. Evaluation of aquifer heterogeneity effects on river flow loss using a transition probability framework

    Science.gov (United States)

    Engdahl, N.B.; Vogler, E.T.; Weissmann, G.S.

    2010-01-01

    River-aquifer exchange is considered within a transition probability framework along the Rio Grande in Albuquerque, New Mexico, to provide a stochastic estimate of aquifer heterogeneity and river loss. Six plausible hydrofacies configurations were determined using categorized drill core and wetland survey data processed through the TPROGS geostatistical package. A base case homogeneous model was also constructed for comparison. River loss was simulated for low, moderate, and high Rio Grande stages and several different riverside drain stage configurations. Heterogeneity effects were quantified by determining the mean and variance of the K field for each realization compared to the root-mean-square (RMS) error of the observed groundwater head data. Simulation results showed that the heterogeneous models produced smaller estimates of loss than the homogeneous approximation. Differences between heterogeneous and homogeneous model results indicate that the use of a homogeneous K in a regional-scale model may result in an overestimation of loss but comparable RMS error. We find that the simulated river loss is dependent on the aquifer structure and is most sensitive to the volumetric proportion of fines within the river channel. Copyright 2010 by the American Geophysical Union.

  18. The effects of racial heterogeneity on mental health: A study of detained youth across multiple counties.

    Science.gov (United States)

    Lau, Katherine S L; Aalsma, Matthew C; Holloway, Evan D; Wiehe, Sarah E; Vachon, David D

    2015-09-01

    A majority of detained adolescents experience mental health and substance use problems. Limited research has examined the interaction between the race/ethnicity of an individual youth and county-level racial heterogeneity on adolescent mental health outcomes. Participants were identified through a statewide mental health screening project that took place in detention centers across 11 different counties in a Midwestern state during January 1, 2008, to May 10, 2010. A total of 23,831 detained youth (ages 11-18 years), identified as non-Hispanic White (46.6%), Black (43.5%), or Hispanic (9.8%), completed a mental health screener that assessed problems in alcohol/drug use, depression-anxiety, anger-irritability, trauma, somatic complaints, and suicide ideation. Census data were gathered to determine the racial heterogeneity of each county and other county-level variables. Hierarchical linear regression analyses were used to test the independent and interactive effects of youth race/ethnicity and county-level variables (including racial heterogeneity of the county) on adolescent mental health. Independent of other community characteristics, as county-level racial heterogeneity increased, mental health problems among detained youth decreased. In future research on the development and persistence of mental health problems in detained youth, both community and individual-level factors should be considered. PMID:26460702

  19. Effect of size and heterogeneity of samples on biomarker discovery: synthetic and real data assessment.

    Directory of Open Access Journals (Sweden)

    Barbara Di Camillo

    Full Text Available MOTIVATION: The identification of robust lists of molecular biomarkers related to a disease is a fundamental step for early diagnosis and treatment. However, methodologies for the discovery of biomarkers using microarray data often provide results with limited overlap. These differences are imputable to 1 dataset size (few subjects with respect to the number of features; 2 heterogeneity of the disease; 3 heterogeneity of experimental protocols and computational pipelines employed in the analysis. In this paper, we focus on the first two issues and assess, both on simulated (through an in silico regulation network model and real clinical datasets, the consistency of candidate biomarkers provided by a number of different methods. METHODS: We extensively simulated the effect of heterogeneity characteristic of complex diseases on different sets of microarray data. Heterogeneity was reproduced by simulating both intrinsic variability of the population and the alteration of regulatory mechanisms. Population variability was simulated by modeling evolution of a pool of subjects; then, a subset of them underwent alterations in regulatory mechanisms so as to mimic the disease state. RESULTS: The simulated data allowed us to outline advantages and drawbacks of different methods across multiple studies and varying number of samples and to evaluate precision of feature selection on a benchmark with known biomarkers. Although comparable classification accuracy was reached by different methods, the use of external cross-validation loops is helpful in finding features with a higher degree of precision and stability. Application to real data confirmed these results.

  20. Effects of Heterogeneity in Residential Preferences on an Agent-Based Model of Urban Sprawl

    Directory of Open Access Journals (Sweden)

    Derek T. Robinson

    2006-06-01

    Full Text Available The ability of agent-based models (ABMs to represent heterogeneity in the characteristics and behaviors of actors enables analyses about the implications of this heterogeneity for system behavior. The importance of heterogeneity in the specification of ABMs, however, creates new demands for empirical support. An earlier analysis of a survey of residential preferences within southeastern Michigan revealed seven groups of residents with similar preferences on similar characteristics of location. In this paper, we present an ABM that represents the process of residential development within an urban system and run it for a hypothetical pattern of environmental variation. Residential locations are selected by residential agents, who evaluate locations on the basis of preference for nearness to urban services, including jobs, aesthetic quality of the landscape, and their similarity to their neighbors. We populate our ABM with a population of residential preferences drawn from the survey results in five different ways: (1 preferences drawn at random; (2 equal preferences based on the mean from the entire survey sample; (3 preferences drawn from a single distribution, whose mean and standard deviation are derived from the survey sample; (4 equal preferences within each of seven groups, based on the group means; and (5 preferences drawn from distributions for each of seven groups, defined by group means and standard deviations. Model sensitivity analysis, based on multiple runs of our model under each case, revealed that adding heterogeneity to agents has a significant effect on model outcomes, measured by aggregate patterns of development sprawl and clustering.

  1. Bony fish and their contribution to marine inorganic carbon cycling

    Science.gov (United States)

    Salter, Michael; Perry, Chris; Wilson, Rod; Harborne, Alistair

    2016-04-01

    Conventional understanding of the marine inorganic carbon cycle holds that CaCO3 (mostly as low Mg-calcite and aragonite) precipitates in the upper reaches of the ocean and sinks to a point where it either dissolves or is deposited as sediment. Thus, it plays a key role controlling the distribution of DIC in the oceans and in regulating their capacity to absorb atmospheric CO2. However, several aspects of this cycle remain poorly understood and have long perplexed oceanographers, such as the positive alkalinity anomaly observed in the upper water column of many of the world's oceans, above the aragonite and calcite saturation horizons. This anomaly would be explained by extensive dissolution of a carbonate phase more soluble than low Mg-calcite or aragonite, but major sources for such phases remain elusive. Here we highlight marine bony fish as a potentially important primary source of this 'missing' high-solubility CaCO3. Precipitation of CaCO3 takes place within the intestines of all marine bony fish as part of their normal physiological functioning, and global production models suggest it could account for up to 45 % of total new marine CaCO3 production. Moreover, high Mg-calcite containing >25 % mol% MgCO3 - a more soluble phase than aragonite - is a major component of these precipitates. Thus, fish CaCO3 may at least partially explain the alkalinity anomaly in the upper water column. However, the issue is complicated by the fact that carbonate mineralogy actually varies among fish species, with high Mg-calcite (HMC), low Mg-calcite (LMC), aragonite, and amorphous calcium carbonate (ACC) all being common products. Using data from 22 Caribbean fish species, we have generated a novel production model that resolves phase proportions. We evaluate the preservation/dissolution potential of these phases and consider potential implications for marine inorganic carbon cycling. In addition, we consider the dramatic changes in fish biomass structure that have resulted

  2. The Effect of Number of Agents on Optimization of adaptivity Join Queries in Heterogeneous Distributed Databases

    Directory of Open Access Journals (Sweden)

    Amir ASIL

    2013-01-01

    Full Text Available Distributed systems signify data distribution, association of activities, and controlling the distributed components of the system. Distributed systems are mostly used to share the workload or transfer data processing functions to a place nearer to those functions. This important task should be mentioned in database query optimization. The growing need for optimizing query processing in databases has given rise to many methods of doing this. This article provides a multi-agent system for heterogeneous distributed databases by combining optimization techniques for processing queries in databases and adaptivity. In this system the effect of the number of agents on optimization of query processing in Heterogeneous distributed databases will be analyzed. In this system an agent has been added to make the database adaptable. In this system the greatness of the effect of number of agents on optimization of processing of joined queries has been analyzed.

  3. The effect of heterogeneous dynamics of online users on information filtering

    Science.gov (United States)

    Chen, Bo-Lun; Zeng, An; Chen, Ling

    2015-11-01

    The rapid expansion of the Internet requires effective information filtering techniques to extract the most essential and relevant information for online users. Many recommendation algorithms have been proposed to predict the future items that a given user might be interested in. However, there is an important issue that has always been ignored so far in related works, namely the heterogeneous dynamics of online users. The interest of active users changes more often than that of less active users, which asks for different update frequency of their recommendation lists. In this paper, we develop a framework to study the effect of heterogeneous dynamics of users on the recommendation performance. We find that the personalized application of recommendation algorithms results in remarkable improvement in the recommendation accuracy and diversity. Our findings may help online retailers make better use of the existing recommendation methods.

  4. Ancient origin of lubricated joints in bony vertebrates

    Science.gov (United States)

    Askary, Amjad; Smeeton, Joanna; Paul, Sandeep; Schindler, Simone; Braasch, Ingo; Ellis, Nicholas A; Postlethwait, John; Miller, Craig T; Crump, J Gage

    2016-01-01

    Synovial joints are the lubricated connections between the bones of our body that are commonly affected in arthritis. It is assumed that synovial joints first evolved as vertebrates came to land, with ray-finned fishes lacking lubricated joints. Here, we examine the expression and function of a critical lubricating protein of mammalian synovial joints, Prg4/Lubricin, in diverse ray-finned fishes. We find that Prg4 homologs are specifically enriched at the jaw and pectoral fin joints of zebrafish, stickleback, and gar, with genetic deletion of the zebrafish prg4b gene resulting in the same age-related degeneration of joints as seen in lubricin-deficient mice and humans. Our data support lubricated synovial joints evolving much earlier than currently accepted, at least in the common ancestor of all bony vertebrates. Establishment of the first arthritis model in the highly regenerative zebrafish will offer unique opportunities to understand the aetiology and possible treatment of synovial joint disease. DOI: http://dx.doi.org/10.7554/eLife.16415.001 PMID:27434666

  5. Viral vaccines for bony fish: past, present and future.

    Science.gov (United States)

    Salgado-Miranda, Celene; Loza-Rubio, Elizabeth; Rojas-Anaya, Edith; García-Espinosa, Gary

    2013-05-01

    Since 1970, aquaculture production has grown. In 2010, it had an annual average rate of 6.3% with 59.9 million tons of product and soon could exceed capture fisheries as a source of fishery products. However, the occurrence of viral diseases continues to be a significant limiting factor and its control is important for the development of this sector. In aquaculture farms, fish are reared under intensive culture conditions, and the use of viral vaccines has enabled an increase in production. Several types of vaccines and strategies of vaccination have been developed; however, this approach has not reached the expected goals in the most susceptible stage (fingerlings). Currently, there are inactivated and recombinant commercial vaccines, mainly for salmonids and cyprinids. In addition, updated genomic and proteomic technology has expedited the research and expansion of new vaccine models, such as those comprised of subunits or DNA. The objective of this review is to cover the various types of viral vaccines that have been developed and are available for bony fishes, as well as the advantages and challenges that DNA vaccines present for massive administration in a growing aquaculture, possible risks for the environment, the controversy regarding genetically modified organisms and possible acceptance by consumers. PMID:23659303

  6. Effect of heterogeneity on the quantitative determination of trace elements in concrete.

    Science.gov (United States)

    Weritz, Friederike; Schaurich, Dieter; Taffe, Alexander; Wilsch, Gerd

    2006-05-01

    Laser-induced breakdown spectroscopy has been used for quantitative measurement of trace elements, e.g. sulfur and chlorine, in concrete. Chloride and sulfate ions have a large effect on the durability of concrete structures, and quantitative measurement is important for condition assessment and quality assurance. Concrete is a highly heterogeneous material in composition and grain-size distribution, i.e. the spatial distribution of elements. Calibration plots were determined by use of laboratory-made reference samples consisting of pressings of cement powder, hydrated cement, cement mortar, and concrete, in which the heterogeneity of the material is increasing because of the aggregates. Coarse aggregate and cement paste are distinguishable by the intensity of the Ca spectral lines. More advanced evaluation is necessary to account for the effect of the fine aggregate. The three series of reference samples enable systematic study of the effects of heterogeneity on spectral intensity, signal fluctuation, uncertainty, and limits of detection. Spatially resolved measurements and many spectra enable statistical evaluation of the data. The heterogeneity has an effect on measurement of the sulfur and chlorine content, because both occur mainly in the cement matrix. Critical chloride concentrations are approximately 0.04% (m/m). The chlorine spectral line at 837.6 nm is evaluated. The natural sulfur content of concrete is approximately 0.1% (m/m). The spectral line at 921.3 nm is evaluated. One future application may be simultaneous determination of the amount of damaging trace elements and the cement content of the concrete. PMID:16520935

  7. Heterogeneity in the effect of regulation on entrepreneurship and entry size

    OpenAIRE

    Silvia Ardagna; Annamaria Lusardi

    2009-01-01

    We use cross-national harmonized micro data from a broad sample of developed and developing countries and investigate the heterogeneity of the effect of entry, contract enforcement regulation, and financial development on both the decision to become an entrepreneur and the level of employment of newly created businesses. We focus on the interaction between the level of regulation and financial development and some individual characteristics that are important determinants of entrepreneurship,...

  8. From concepts, theory, and evidence of heterogeneity of treatment effects to methodological approaches: a primer

    OpenAIRE

    Willke Richard J; Zheng Zhiyuan; Subedi Prasun; Althin Rikard; Mullins C Daniel

    2012-01-01

    Abstract Implicit in the growing interest in patient-centered outcomes research is a growing need for better evidence regarding how responses to a given intervention or treatment may vary across patients, referred to as heterogeneity of treatment effect (HTE). A variety of methods are available for exploring HTE, each associated with unique strengths and limitations. This paper reviews a selected set of methodological approaches to understanding HTE, focusing largely but not exclusively on th...

  9. Spatial Heterogeneity in Spillover Effects of Assisted and Unassisted Rental Housing

    OpenAIRE

    Julia Koschinsky

    2008-01-01

    Three new contributions are added to the literature on subsidized rental housing impacts on nearby property values: 1) A primary focus on the spatial heterogeneity of these effects which warrants caution regarding citywide results; 2) an analysis by zoning area, and 3) a comparison of impacts with unsubsidized apartments. An adjusted-interrupted time series (difference-in-difference) model is estimated with a comprehensive dataset for Seattle, WA (1987-97). Contrary to NIMBY expectations, the...

  10. Cost-effectiveness of alternative green payment policies for conservation technology adoption with heterogeneous land quality

    OpenAIRE

    Khanna, Madhu; Isik, Murat; Zilberman, David

    2002-01-01

    This paper quantitatively analyses the cost-effectiveness of alternative green payment policies designed to achieve a targeted level of pollution control by heterogeneous micro units. These green payment policies include cost-share subsidies that share the fixed costs of adoption of a conservation technology and/or input reduction subsidies to reduce the use of a polluting input. The paper shows that unlike a pollution tax that achieves abatement through three mechanisms, a negative extensive...

  11. Effect of Spatial Heterogeneity on Near-Limit Propagation of a Stable Detonation

    OpenAIRE

    Li, Jianling; Mi, XiaoCheng; Higgins, Andrew J.

    2014-01-01

    The effect of introducing a spatial heterogeneity into an explosive medium is studied computationally by examining the detonation velocity near the limit to propagation in a thin explosive layer. The explosive system studied is an ideal gas with a single exothermic reaction governed by a pressure-dependent reaction rate ($p^n$) with a pressure exponent of $n = 3$. A pressure-dependent reaction rate, rather than the exponential dependence of reaction on temperature of Arrhenius kinetics, is us...

  12. Effective reactive surface area: An anisotropic property of physically and chemically heterogeneous porous media

    International Nuclear Information System (INIS)

    Although transport calculations are often formulated in terms of mass-based isotropic distribution coefficients, it is the abundance of reactive surface areas of subsurface materials that controls contaminant adsorption. In water-saturated homogeneous systems devoid of advective fluxes (e.g., batch experiments), the available reactive surface area is similar to the total surface area (as measured by conventional methods such as BET gas adsorption). However, in physically and chemically heterogeneous systems with advective fluxes, the effective reactive surface area (i.e., the surface area that a packet of advecting water interacts with) is smaller than the laboratory measured surface area and is a complex function of advective velocity and the correlation structures of the physical and chemical heterogeneities. Theoretical derivations for an important but simple type of heterogeneity (fine-scale horizontal layering) suggest that the effective reactive surface area is an anisotropic property of the medium and is inversely correlated with the anisotropy in hydraulic conductivity. The implications of reactive transport anisotropy include the concept that the retardation factor should be treated as a directional property rather than being treated as a constant. Furthermore, because of the inverse relationship between effective reactive surface area and hydraulic conductivity, batch adsorption experiments tend to overestimate the retention of contaminants relative to intact natural materials

  13. Effect of Spatial Heterogeneity on Near-Limit Propagation of a Stable Detonation

    CERN Document Server

    Li, Jianling; Higgins, Andrew J

    2014-01-01

    The effect of introducing a spatial heterogeneity into an explosive medium is studied computationally by examining the detonation velocity near the limit to propagation in a thin explosive layer. The explosive system studied is an ideal gas with a single exothermic reaction governed by a pressure-dependent reaction rate ($p^n$) with a pressure exponent of $n = 3$. A pressure-dependent reaction rate, rather than the exponential dependence of reaction on temperature of Arrhenius kinetics, is used so that the detonation wave is stable in the homogeneous case and can be modelled with simple, analytical techniques, and thus the effect of introducing heterogeneity can be clearly identified. The two-dimensional slab of explosive is bounded by a layer of inert gas with the same thermodynamic properties as the explosive. The heterogeneity is introduced into the explosive via a large-amplitude, two-dimensional sinusoidal ripple in density in the initialization of the simulation, while maintaining a constant pressure. T...

  14. Effect of heterogeneous catalysts on the radiolysis of aqueous phenol solutions

    International Nuclear Information System (INIS)

    A carbon sorbent or a heterogeneous catalyst on a carbon support had a surface-dependent effect on the route and quantitative characteristics pertaining to radiative decomposition of phenol adsorbed from an aqueous solution in a flow system. The heterogeneous catalysts studied were manganese dioxide, platinum, nickel, and nickel-palladium deposited on activated carbon brands AG-3 and BAU (birch carbon) as well as on a spherical carbon sorbent. The nickel-containing catalysts were modified by addition of a 12th series, reduced heteropolytungstate (HPT). The manganese dioxide was deposited on AG-3 carbon by a radiation-chemical method. A weighed amount of the sorent was impregnated with a potassium permanganate solution and then irradiated from a γ source

  15. Perceived Disagreement and Heterogeneity in Social Networks: Distinct Effects on Political Participation.

    Science.gov (United States)

    Guidetti, Margherita; Cavazza, Nicoletta; Graziani, Anna Rita

    2016-01-01

    Although the coexistence of conflicting opinions in society is the very core of democracy, people's tendency to avoid conflict could keep them away from political discussion and participation. On the other hand, being exposed to diverse political views could motivate citizens to participate. We conducted secondary analyses on two 2013 ITANES (Italian National Election Studies) probability samples in order to test the hypotheses that perceived network disagreement (between an individual and her/his discussion partners) and heterogeneity (among discussants holding different political opinions) exert independent and opposite effects on political participation through motivation and knowledge. Results converged in showing that disagreement dampened, while heterogeneity encouraged, political participation (voting, propensity to abstain in future, offline and online activism, and timing of vote decision) by decreasing or increasing, respectively, political interest and, in turn, knowledge. PMID:26390803

  16. Differential effects of excitatory and inhibitory heterogeneity on the gain and asynchronous state of sparse cortical networks

    Directory of Open Access Journals (Sweden)

    Jorge F Mejias

    2014-09-01

    Full Text Available Recent experimental and theoretical studies have highlighted the importance of cell-to-cell differences in the dynamics and functions of neural networks, such as in different types of neural coding or synchronization. It is still not known, however, how neural heterogeneity can affect cortical computations, or impact the dynamics of typical cortical circuits constituted of sparse excitatory and inhibitory networks. In this work, we analytically and numerically study the dynamics of a typical cortical circuit with a certain level of neural heterogeneity. Our circuit includes realistic features found in real cortical populations, such as network sparseness, excitatory and inhibitory subpopulations of neurons, and different cell-to-cell heterogeneities for each type of population in the system. We find highly differentiated roles for heterogeneity, depending on the subpopulation in which it is found. In particular, while heterogeneity among excitatory neurons nonlinearly increases the mean firing rate and linearizes the f-I curves, heterogeneity among inhibitory neurons may decrease the network activity level and induces divisive gain effects in the f-I curves of the excitatory cells, providing an effective gain control mechanism to influence information flow. In addition, we compute the conditions for stability of the network activity, finding that the synchronization onset is robust to inhibitory heterogeneity, but it shifts to lower input levels for higher excitatory heterogeneity. Finally, we provide an extension of recently reported heterogeneity-induced mechanisms for signal detection under rate coding, and we explore the validity of our findings when multiple sources of heterogeneity are present. These results allow for a detailed characterization of the role of neural heterogeneity in asynchronous cortical networks.

  17. Heterogeneous Suppression of Sequential Effects in Random Sequence Generation, but Not in Operant Learning

    Science.gov (United States)

    Shteingart, Hanan; Loewenstein, Yonatan

    2016-01-01

    There is a long history of experiments in which participants are instructed to generate a long sequence of binary random numbers. The scope of this line of research has shifted over the years from identifying the basic psychological principles and/or the heuristics that lead to deviations from randomness, to one of predicting future choices. In this paper, we used generalized linear regression and the framework of Reinforcement Learning in order to address both points. In particular, we used logistic regression analysis in order to characterize the temporal sequence of participants’ choices. Surprisingly, a population analysis indicated that the contribution of the most recent trial has only a weak effect on behavior, compared to more preceding trials, a result that seems irreconcilable with standard sequential effects that decay monotonously with the delay. However, when considering each participant separately, we found that the magnitudes of the sequential effect are a monotonous decreasing function of the delay, yet these individual sequential effects are largely averaged out in a population analysis because of heterogeneity. The substantial behavioral heterogeneity in this task is further demonstrated quantitatively by considering the predictive power of the model. We show that a heterogeneous model of sequential dependencies captures the structure available in random sequence generation. Finally, we show that the results of the logistic regression analysis can be interpreted in the framework of reinforcement learning, allowing us to compare the sequential effects in the random sequence generation task to those in an operant learning task. We show that in contrast to the random sequence generation task, sequential effects in operant learning are far more homogenous across the population. These results suggest that in the random sequence generation task, different participants adopt different cognitive strategies to suppress sequential dependencies when

  18. Effect of crustal heterogeneities and effective rock strength on the formation of HP and UHP rocks.

    Science.gov (United States)

    Reuber, Georg; Kaus, Boris; Schmalholz, Stefan; White, Richard

    2015-04-01

    next step, we performed several hundred numerical simulations to understand the effects of km-scale heterogeneities and material parameters on pressure magnitudes, using a model setup that is otherwise very similar to the one of Li et al. (2010). Results show that significant non-lithostatic pressures occur if (lower) crustal rocks are dry or if km-scale (nappe-sized) heterogeneities with dryer rocks are present within the crust. Overpressure magnitudes can be up to 1 GPa or 100% and in some cases rock assemblages are temporarily in the coesite stability field at a depth of only 40 km, followed by rapid exhumation to the surface. Tectonic overpressures can vary strongly in magnitude versus time, but peak pressures are present sufficiently long for metamorphic reactions to occur. The presence of heterogeneities can affect the crustal-scaled deformation pattern, and the effective friction angle of crustal-scale rocks (or the dryness of these rocks) is a key parameter that determines the magnitude of non-lithostatic pressures. Our results thus reconcile previous findings and highlight the importance of having an accurate knowledge of the fluid-pressure, initial crustal structure and rock composition during continental collision. If rocks are dry by the time they enter a subduction zone, or are stronger/dryer than surrounding rocks, they are likely to develop significantly higher pressures than nearby rocks. This might explain the puzzling observation that some nappes have very high peak pressures, while juxtaposed nappes have much lower values, without clear structural evidence for deep burial and exhumation along a subduction channel of the high-pressure nappe. Our models might also give a partial explanation of why the reported timescales for high and ultra-high pressure stages of peak metamorphism are often very short. References: Burov, E., Francois, T., Agard, P., Le Pourhiet, L., Meyer, B., Tirel, C., Lebedev, S., Yamato, P., Brun, J.-P., 2014. Tectonophysics

  19. Importance of bony analysis for interpreting ear CT scans: part three

    International Nuclear Information System (INIS)

    The accurate description of bony changes in ear CT scans has a great diagnostic and therapeutic impact. The third part shows the way to analyze bone remodeling when CT scan is performed for tumors in the vicinity of the temporal bone, for intra temporal lesions of the facial nerve and for external auditory canal malformations. It demonstrates how bony analysis should be included in postoperative report of ear CT scan. The importance of bony signs in tumors and pseudo tumors of the inner ear are outlined. (authors)

  20. CT image evaluation of the internal rotation limit prior to bony impingement after total hip arthroplasty

    International Nuclear Information System (INIS)

    This study evaluated the internal rotation limit prior to bony impingement of the proximal femur on the pelvis after total hip arthroplasty (THA). Reconstructed computed tomography (CT) images of 90 deg hip flexion were used to simulate the internal rotation limit against safety limits measured intraoperatively. Ninety joints in 86 subjects (12 men and 74 women) underwent THA for the treatment of secondary coxarthrosis. The correlation between the internal rotation limit prior to the bony impingement intraoperatively and the simulated internal rotation angle on the reconstructed CT image was statistically significant. We provide a new method to simulate the internal rotation limit prior to bony impingement based on postoperative CT. (author)

  1. Algodystrophy in children and young adults with isotopic bony hypofixation. A propos of 5 observations

    International Nuclear Information System (INIS)

    The authors report 5 observations of young adults 3 teen-agers and 2 children suffering from algodystrophy, and in whom isotopic exploration of the skeleton disclosed a clear bony hypofixation during the entire evolution. These observations confirm their 1981 work concerning a young adult suffering from algodystrophy with isotopic bony hypofixation. Recent Canadian and American studies emphasize also the frequency of isotopic hypofixation in children algodystrophy. It seems, therefore, that isotopic bony hypofixation (linked perhaps to a decreased blood flow), is rather specific of algodystrophy in young subjects

  2. A heterogeneous chemistry model for acid rain`s effect on ozone

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Tao [Univ. of New York, Stonybrook, NY (United States)

    1995-11-01

    A computer model for simulating heterogeneous reactions in cloud is developed to determine the S(IV) species` effect on ozone. Crutzen claims that NO{sub x}, HO{sub x} families and H{sub 2}CO in the troposphere can decrease ozone by 5 to 10%. However, is this claim valid for a SO{sub x} polluted atmosphere? The SO{sub x} family reacts with the ozone destroyers. These reactions seem to be significant enough to reduce the H{sub 2}CO`s destructive effect on ozone.

  3. Effects of the heterogeneous landscape on a predator-prey system

    Science.gov (United States)

    Lee, Sang-Hee

    2010-01-01

    In order to understand how a heterogeneous landscape affects a predator-prey system, a spatially explicit lattice model consisting of predators, prey, grass, and landscape was constructed. The predators and preys randomly move on the lattice space and the grass grows in its neighboring site according to its growth probability. When predators and preys meet at the same site at the same time, a number of prey, equal to the number of predators are eaten. This rule was also applied to the relationship between the prey and grass. The predator (prey) could give birth to an offspring when it ate prey (grass), with a birth probability. When a predator or prey animal was initially introduced, or newly born, its health state was set at a given high value. This health state decreased by one with every time step. When the state of an animal decreased to less than zero, the animal died and was removed from the system. The heterogeneous landscape was characterized by parameter H, which controlled the heterogeneity according to the neutral model. The simulation results showed that H positively or negatively affected a predator’s survival, while its effect on prey and grass was less pronounced. The results can be understood by the disturbance of the balance between the prey and predator densities in the areas where the animals aggregated.

  4. Effect of Multipoint Heterogeneity on Nonlinear Transformations for Geological Modeling: Porosity-Permeability Relations Revisited

    Institute of Scientific and Technical Information of China (English)

    J A Vargas-Guzmán

    2008-01-01

    An analysis of statistical expected values for transformations is performed in this study to quantify the effect of heterogeneity on spatial geological modeling and evaluations. Algebraic transformations are frequently applied to data from logging to allow for the modeling of geological properties. Transformations may be powers, products, and exponential operations which are commonly used in well-known relations (e.g., porosity-permeability transforms). The results of this study show that correct computations must account for residual transformation terms which arise due to lack of independence among heterogeneous geological properties. In the case of an exponential porosity-permeability transform, the values may be positive. This proves that a simple exponential model back-transformed from linear regression underestimates permeability. In the case of transformations involving two or more properties, residual terms may represent the contribution of heterogeneous components which occur when properties vary together, regardless of a pair-wise linear independence. A consequence of power- and product-transform models is that regression equationswithin those transformations need corrections via residual cumulants. A generalization of this result isthat transformations of multivariate spatial attributes require multiple-point random variable relations. This analysis provides practical solutions leading to a methodology for nonlinear modeling using correct back transformations in geology.

  5. Study of the heterogeneity effects of lung in the evaluation of absorbed dose in radiotherapy

    International Nuclear Information System (INIS)

    The main objective of radiotherapy is to deliver the highest possible dose to the tumour, in order to destroy it, reducing as much as possible the doses to healthy tissues adjacent to the target volume. Therefore, it is necessary to do a planning of the treatment. The more complex is the treatment, the more difficult the planning will be, demanding computation sophisticated methods in its execution, in order to consider the heterogeneities present in the human body. Additionally, with the appearing of new radiotherapeutic techniques, that used irradiation fields of small area, for instance, the intensity modulated radiotherapy, the difficulties for the execution of a reliable treatment planning, became still larger. In this work it was studied the influence of the lung heterogeneity in the planning of the curves of percentage depth dose, PDP, obtained with the EclipseR planning system for different sizes of irradiation fields, using the correction algorithms for heterogeneities available in the planning system: modified Batho, general Batho and equivalent tissue-air ratio. A thorax phantom, manufactured in acrylic, containing a region made of cork to simulate the lung tissue, was used. The PDP curves generated by the planning system were compared to those obtained by Monte Carlo simulation and with the use of thermoluminescent, TL, dosimetry. It was verified that the algorithms used by the EclipseR system for the correction of heterogeneity effects are not able to generate correct results for PDP curves in the case of small fields, occurring differences of up to 100%, when the 1x1 cm2 treatment field is considered. These differences can cause a considerable subdosage in the lung tissue, reducing the possibility of the patient cure. (author)

  6. Accounting for Heterogeneity in Relative Treatment Effects for Use in Cost-Effectiveness Models and Value-of-Information Analyses.

    Science.gov (United States)

    Welton, Nicky J; Soares, Marta O; Palmer, Stephen; Ades, Anthony E; Harrison, David; Shankar-Hari, Manu; Rowan, Kathy M

    2015-07-01

    Cost-effectiveness analysis (CEA) models are routinely used to inform health care policy. Key model inputs include relative effectiveness of competing treatments, typically informed by meta-analysis. Heterogeneity is ubiquitous in meta-analysis, and random effects models are usually used when there is variability in effects across studies. In the absence of observed treatment effect modifiers, various summaries from the random effects distribution (random effects mean, predictive distribution, random effects distribution, or study-specific estimate [shrunken or independent of other studies]) can be used depending on the relationship between the setting for the decision (population characteristics, treatment definitions, and other contextual factors) and the included studies. If covariates have been measured that could potentially explain the heterogeneity, then these can be included in a meta-regression model. We describe how covariates can be included in a network meta-analysis model and how the output from such an analysis can be used in a CEA model. We outline a model selection procedure to help choose between competing models and stress the importance of clinical input. We illustrate the approach with a health technology assessment of intravenous immunoglobulin for the management of adult patients with severe sepsis in an intensive care setting, which exemplifies how risk of bias information can be incorporated into CEA models. We show that the results of the CEA and value-of-information analyses are sensitive to the model and highlight the importance of sensitivity analyses when conducting CEA in the presence of heterogeneity. The methods presented extend naturally to heterogeneity in other model inputs, such as baseline risk. PMID:25712447

  7. A Comparative Dosimetric Analysis of the Effect of Heterogeneity Corrections Used in Three Treatment Planning Algorithms

    Science.gov (United States)

    Herrick, Andrea Celeste

    Successful treatment in radiation oncology relies on the evaluation of a plan for each individual patient based on delivering the maximum dose to the tumor while sparing the surrounding normal tissue (organs at risk) in the patient. Organs at risk (OAR) typically considered include the heart, the spinal cord, healthy lung tissue, and any other organ in the vicinity of the target that is not affected by the disease being treated. Depending on the location of the tumor and its proximity to these OARs, several plans may be created and evaluated in order to assess which "solution" most closely meets all of the specified criteria. In order to successfully review a treatment plan and take the correct course of action, a physician needs to rely on the computer model (treatment planning algorithm) of dose distribution to reconstruct CT scan data to proceed with the plan that best achieves all of the goals. There are many available treatment planning systems from which a Radiation Oncology center can choose from. While the radiation interactions considered are identical among clinics, the way the chosen algorithm handles these interactions can vary immensely. The goal of this study was to provide a comparison between two commonly used treatment planning systems (Pinnacle and Eclipse) and their associated dose calculation algorithms. In order to this, heterogeneity correction models were evaluated via test plans, and the effects of going from heterogeneity uncorrected patient representation to a heterogeneity correction representation were studied. The results of this study indicate that the actual dose delivered to the patient varies greatly between treatment planning algorithms in areas of low density tissue such as in the lungs. Although treatment planning algorithms are attempting to come to the same result with heterogeneity corrections, the reality is that the results depend strongly on the algorithm used in the situations studied. While the Anisotropic Analytic Method

  8. Effects of Normalized Difference Vegetation Index and Related Wavebands' Characteristics on Detecting Spatial Heterogeneity Using Variogram-based Analysis

    Institute of Scientific and Technical Information of China (English)

    WEN Zhaofei; ZHANG Ce; ZHANG Shuqing; DING Changhong; LIU Chunyue; PAN Xin; LI Huapeng; SUN Yan

    2012-01-01

    Spatial heterogeneity is widely used in diverse applications,such as recognizing ecological process,guiding ecological restoration,managing land use,etc.Many researches have focused on the inherent scale multiplicity of spatial heterogeneity by using various environmental variables.How these variables affect their corresponding spatial heterogeneities,however,have received little attention.In this paper,we examined the effects of characteristics of normalized difference vegetation index (NDVI) and its related bands variable images,namely red and near infrared (NIR),on their corresponding spatial heterogeneity detection based on variogram models.In a coastal wetland region,two groups of study sites with distinct fractal vegetation cover were tested and analyzed.The results show that:1) in high fractal vegetation cover (H-FVC) area,NDVI and NIR variables display a similar ability in detecting the spatial heterogeneity caused by vegetation growing status structure; 2) in low fractal vegetation cover (L-FVC) area,the NIR and red variables outperform NDVI in the survey of soil spatial heterogeneity; and 3) generally,NIR variable is ubiquitously applicable for vegetation spatial heterogeneity investigation in different fractal vegetation covers.Moreover,as variable selection for remote sensing applications should fully take the characteristics of variables and the study object into account,the proposed variogram analysis method can make the variable selection objectively and scientifically,especially in studies related to spatial heterogeneity using remotely sensed data.

  9. Heterogeneity in cost-effectiveness of lifestyle counseling for metabolic syndrome risk groups -primary care patients in Sweden

    OpenAIRE

    Feldman, Inna; Hellström, Lennart; Johansson, Pia

    2013-01-01

    BACKGROUND: Clinical trials have indicated that lifestyle interventions for patients with lifestyle-related cardiovascular and diabetes risk factors (the metabolic syndrome) are cost-effective. However, patient characteristics in primary care practice vary considerably, i.e. they exhibit heterogeneity in risk factors. The cost-effectiveness of lifestyle interventions is likely to differ over heterogeneous patient groups. METHODS: Patients (62 men, 80 women) in the Kalmar Metabolic Syndrome Pr...

  10. Study of the effect of heterogeneity of the control rods in the PHÉNIX reactor

    International Nuclear Information System (INIS)

    Neutron cross-section processing for fast reactor sub-regions containing control rods has to take into account heterogeneity effects in order to get a reliable assessment of the control rod reactivity worth. Several numerical methods have been developed in the past with a support of experimental campaigns and are employed nowadays to reasonably treat such effects by using sophisticated neutronics codes. The SIMMER code is employed at KIT for severe accident analyses of metal-cooled fast reactors and other reactor systems. Neutron cross-sections are processed in the original SIMMER version by approximating each reactor region as a homogeneous medium. This simplified treatment results in the overestimation of the control rod worth. Efforts are therefore going on to extend the code in order to take into account heterogeneity effects in the control rod subassemblies. In this paper a technique proposed in the past was applied to take into account these effects as basis for further SIMMER extensions. With this aim a 3D (HEX-Z) ERANOS model of the PHÉNIX reactor has been assessed. Further, the corresponding 3D (XYZ) PARTISN model has been employed, the latter code being now introduced in SIMMER as a new neutronics solver. Results show that the employed technique improves the capability of SIMMER and ERANOS codes to predict the control rod reactivity worths. Results also show that the HEX-Z ERANOS and XYZ PARTISN models for PHÉNIX reasonably agree. (author)

  11. Efficiency effects of observed and unobserved heterogeneity: Evidence from Norwegian electricity distribution networks

    International Nuclear Information System (INIS)

    Since the 1990s, efficiency and benchmarking analysis has increasingly been used in network utilities research and regulation. A recurrent concern is the effect of observable environmental factors that are beyond the influence of firms and unobserved factors that are not identifiable on measured cost and quality performance of firms. This paper analyses the effect of observed geographic and weather factors and unobserved heterogeneity on a set of 128 Norwegian electricity distribution utilities for the 2001–2004 period. We utilise data on 78 geographic and weather variables to identify real economic inefficiency while controlling for observed and unobserved heterogeneity. We use the Factor Analysis technique to reduce the number of environmental factors into few composite variables and to avoid the problem of multicollinearity. In order to identify firm-specific inefficiency, we then estimate a pooled version of the established stochastic frontier model of Aigner et al. (1977) and the recent true random effects model of Greene (2004; 2005a,b) without and with environmental variables. The results indicate that the observed environmental factors have a rather limited influence on the utilities' average efficiency and the efficiency rankings. Moreover, the difference between the average efficiency scores and the efficiency rankings among the pooled and the true random effects models imply that the type of SFA model used is highly influencing the efficiency estimates.

  12. Effects of farm heterogeneity and methods for upscaling on modelled nitrogen losses in agricultural landscapes

    Energy Technology Data Exchange (ETDEWEB)

    Dalgaard, T., E-mail: tommy.dalgaard@agrsci.dk [Aarhus University, Department of Agroecology, Blichers Alle 20, P.O. Box 50, DK-8830 Tjele (Denmark); Hutchings, N. [Aarhus University, Department of Agroecology, Blichers Alle 20, P.O. Box 50, DK-8830 Tjele (Denmark); Dragosits, U. [CEH Edinburgh, Bush Estate, Penicuik, Midlothian EH26 0QB, Scotland (United Kingdom); Olesen, J.E.; Kjeldsen, C. [Aarhus University, Department of Agroecology, Blichers Alle 20, P.O. Box 50, DK-8830 Tjele (Denmark); Drouet, J.L.; Cellier, P. [INRA, UMR Environnement et Grandes Cultures, BP 01, 78850 Thiverval-Grignon (France)

    2011-11-15

    The aim of this study is to illustrate the importance of farm scale heterogeneity on nitrogen (N) losses in agricultural landscapes. Results are exemplified with a chain of N models calculating farm-N balances and distributing the N-surplus to N-losses (volatilisation, denitrification, leaching) and soil-N accumulation/release in a Danish landscape. Possible non-linearities in upscaling are assessed by comparing average model results based on (i) individual farm level calculations and (ii) averaged inputs at landscape level. Effects of the non-linearities that appear when scaling up from farm to landscape are demonstrated. Especially in relation to ammonia losses the non-linearity between livestock density and N-loss is significant (p > 0.999), with around 20-30% difference compared to a scaling procedure not taking this non-linearity into account. A significant effect of farm type on soil N accumulation (p > 0.95) was also identified and needs to be included when modelling landscape level N-fluxes and greenhouse gas emissions. - Highlights: > Farm-N balances and the distribution on types of N-losses are modelled for 56 farms. > Farm type significantly affects N-losses and soil-N accumulation. > A non-linear relation between livestock density and ammonia loss is identified. > Approaches for upscaling from farm to landscape level are discussed. > Accounting farm heterogeneity is important when upscaling N-losses. - This study illustrates the importance of including non-linear effects of farm and landscape heterogeneity on the modelling and upscaling of farm nitrogen losses and greenhouse gas emissions in agricultural landscapes.

  13. Effects of farm heterogeneity and methods for upscaling on modelled nitrogen losses in agricultural landscapes

    International Nuclear Information System (INIS)

    The aim of this study is to illustrate the importance of farm scale heterogeneity on nitrogen (N) losses in agricultural landscapes. Results are exemplified with a chain of N models calculating farm-N balances and distributing the N-surplus to N-losses (volatilisation, denitrification, leaching) and soil-N accumulation/release in a Danish landscape. Possible non-linearities in upscaling are assessed by comparing average model results based on (i) individual farm level calculations and (ii) averaged inputs at landscape level. Effects of the non-linearities that appear when scaling up from farm to landscape are demonstrated. Especially in relation to ammonia losses the non-linearity between livestock density and N-loss is significant (p > 0.999), with around 20-30% difference compared to a scaling procedure not taking this non-linearity into account. A significant effect of farm type on soil N accumulation (p > 0.95) was also identified and needs to be included when modelling landscape level N-fluxes and greenhouse gas emissions. - Highlights: → Farm-N balances and the distribution on types of N-losses are modelled for 56 farms. → Farm type significantly affects N-losses and soil-N accumulation. → A non-linear relation between livestock density and ammonia loss is identified. → Approaches for upscaling from farm to landscape level are discussed. → Accounting farm heterogeneity is important when upscaling N-losses. - This study illustrates the importance of including non-linear effects of farm and landscape heterogeneity on the modelling and upscaling of farm nitrogen losses and greenhouse gas emissions in agricultural landscapes.

  14. Distribution of internal strains around bony prominences in pigs.

    Science.gov (United States)

    Solis, Leandro R; Liggins, Adrian B; Seres, Peter; Uwiera, Richard R E; Poppe, Niek R; Pehowich, Enid; Thompson, Richard B; Mushahwar, Vivian K

    2012-08-01

    Deep tissue injury (DTI) is a type of pressure ulcer in which tissue breakdown initiates at the bone-muscle interface under intact skin. Excessive deformation in the soft tissue, particularly around bony prominences, is believed to be one of the causes leading to the development of DTI. The main goal of this study was to measure the magnitude and distribution of strains within muscles surrounding the ischial tuberosities, induced by levels of external loading that encompass the range of loading experienced by the soft tissue in seated individuals. The experiments were conducted in adult pigs with intact spinal cords (n = 5) and pigs with partial spinal cord injury (SCI) (n = 2), one of which also had a DTI. A secondary goal was to obtain a preliminary assessment regarding the capacity of intermittent electrical stimulation (IES), an intervention for preventing the formation of DTI, to counteract the muscle compression caused by external loading. In intact animals, muscles subjected to external loads equivalent to 25% of body weight experienced maximal principal strains, minimal principal strains, and shear strains of 0.68, -0.3, and 0.4, respectively. These magnitudes increased by 91.9, 17.6, and 87.5%, respectively, when external loading increased to 50% body weight. Minimal to no further increases in strain magnitudes were seen with the 75% body weight loading level. In one animal with SCI and no DTI, strain magnitudes were on average 9.7% higher than those in the intact animals at the corresponding loading levels. The presence of a DTI in another animal with SCI reduced strain magnitudes by 28% compared to intact animals. The regions in the muscle that underwent the largest deformations were those between the ischial tuberosity and the external surface, and up to 2 cm ventral to the ischial tuberosity (furthest measured). Muscle contractions produced by IES increased the thickness of the tissue between the ischial tuberosities and skin during the period of

  15. Time-resolved diffused optical characterization of key tissue constituents of human bony prominence locations

    Science.gov (United States)

    Konugolu Venkata Sekar, Sanathana; Farina, Andrea; Martinenghi, Edoardo; Dalla Mora, Alberto; Taroni, Paola; Pifferi, Antonio; Negredo, Eugènia; Puig, Jordi; Escrig, Roser; Rosales, Quim; Lindner, Claus; Pagliazzi, Marco; Durduran, Turgut

    2015-07-01

    We report a broadband time-resolved characterization of selected bony prominence locations of the human body. A clinical study was performed at six different bony prominence locations of 53 subjects. A portable broadband time-resolved system equipped with pulse drift and distortion compensation strategy was used for absorption and scattering measurements. Key tissue constituents were quantified as a pilot step towards non-invasive optical assessment of bone pathologies.

  16. Assessment of the effect of reduced compositional heterogeneity on fracture resistance of human cortical bone using finite element modeling.

    Science.gov (United States)

    Demirtas, Ahmet; Curran, Erin; Ural, Ani

    2016-10-01

    The recent reports of atypical femoral fracture (AFF) and its possible association with prolonged bisphosphonate (BP) use highlighted the importance of a thorough understanding of mechanical modifications in bone due to bisphosphonate treatment. The reduced compositional heterogeneity is one of the modifications in bone due to extensive suppression of bone turnover. Although experimental evaluations suggested that compositional changes lead to a reduction in the heterogeneity of elastic properties, there is limited information on the extent of influence of reduced heterogeneity on fracture resistance of cortical bone. As a result, the goal of the current study is to evaluate the influence of varying the number of unique elastic and fracture properties for osteons, interstitial bone, and cement lines on fracture resistance across seven different human cortical bone specimens using finite element modeling. Fracture resistance of seven human cortical bone samples under homogeneous and three different heterogeneous material levels was evaluated using a compact tension test setup. The simulation results predicted that the crack volume was the highest for the models with homogeneous material properties. Increasing heterogeneity resulted in a lower amount of crack volume indicating an increase in fracture resistance of cortical bone. This reduction was observed up to a certain level of heterogeneity after which further beneficial effects of heterogeneity diminished suggesting a possible optimum level of heterogeneity for the bone tissue. The homogeneous models demonstrated limited areas of damage with extensive crack formation. On the other hand, the heterogeneity in the material properties led to increased damage volume and a more variable distribution of damage compared to the homogeneous models. This resulted in uncracked regions which tended to have less damage accumulation preventing extensive crack propagation. The results also showed that the percent osteonal area

  17. Heterogeneity of Rapid Sand Filters and Its Effect on Contaminant Transport and Nitrification Performance

    DEFF Research Database (Denmark)

    Lopato, Laure Rose; Galaj, Zofia; Delpont, Sébastien;

    2011-01-01

    Laboratory and full-scale experiments were conducted to investigate the development and effect of heterogeneity caused by filter media nonuniformity, biofilm, particles, precipitates, and gas bubbles in rapid sand filters used for drinking-water treatment. Salt tracer experiments were conducted in...... laboratory columns and in a waterworks, where a new tracer method for rapid sand filters was developed. Pore-water velocities and dispersivities were estimated by fitting an analytical solution to the measured breakthrough curves. Results of the column experiments showed an increase in average longitudinal...

  18. The effect of spatial heterogeneity on nitrate reduction in soil systems

    DEFF Research Database (Denmark)

    Pedersen, Lasse Lu

    hand governed by formation by oxidation of ammonia-N, and on the other hand by removal a removal by two dissimilatory nitrate reduction processes:denitrification, in which nitrate is converted to the gaseous compounds dinitrogen and nitrous oxide, and dissimilatory nitrate reduction to ammonium, DNRA...... nitrate, and can be assimilated into organic matter, effectively bypassing both denitrification and dinitrogen fixation and conserving nitrogen in the ecosystem. It is well established that soil is an extremely heterogeneous environment, not merely on a macroscopic level, but also on a microscopic level...

  19. Cementless Titanium Mesh Fixation of Osteoporotic Burst Fractures of the Lumbar Spine Leads to Bony Healing: Results of an Experimental Sheep Model

    Science.gov (United States)

    Roepenack, Paula; Roesner, Jan; Herlyn, Philipp Karl Ewald; Martin, Heiner; Reichel, Martin; Rotter, Robert; Vollmar, Brigitte; Mittlmeier, Thomas; Gradl, Georg

    2016-01-01

    Introduction. Current treatment strategies for osteoporotic vertebral compression fractures (VCFs) focus on cement-associated solutions. Complications associated with cement application are leakage, embolism, adjacent fractures, and compromise in bony healing. This study comprises a validated VCF model in osteoporotic sheep in order to (1) evaluate a new cementless fracture fixation technique using titanium mesh implants (TMIs) and (2) demonstrate the healing capabilities in osteoporotic VCFs. Methods. Twelve 5-year-old Merino sheep received ovariectomy, corticosteroid injections, and a calcium/phosphorus/vitamin D-deficient diet for osteoporosis induction. Standardized VCFs (type AO A3.1) were created, reduced, and fixed using intravertebral TMIs. Randomly additional autologous spongiosa grafting (G1) or no augmentation was performed (G2, n = 6 each). Two months postoperatively, macroscopic, micro-CT and biomechanical evaluation assessed bony consolidation. Results. Fracture reduction succeeded in all cases without intraoperative complications. Bony consolidation was proven for all cases with increased amounts of callus development for G2 (58.3%). Micro-CT revealed cage integration. Neither group showed improved results with biomechanical testing. Conclusions. Fracture reduction/fixation using TMIs without cement in osteoporotic sheep lumbar VCF resulted in bony fracture healing. Intravertebral application of autologous spongiosa showed no beneficial effects. The technique is now available for clinical use; thus, it offers an opportunity to abandon cement-associated complications. PMID:27019848

  20. Cementless Titanium Mesh Fixation of Osteoporotic Burst Fractures of the Lumbar Spine Leads to Bony Healing: Results of an Experimental Sheep Model.

    Science.gov (United States)

    Eschler, Anica; Roepenack, Paula; Roesner, Jan; Herlyn, Philipp Karl Ewald; Martin, Heiner; Reichel, Martin; Rotter, Robert; Vollmar, Brigitte; Mittlmeier, Thomas; Gradl, Georg

    2016-01-01

    Introduction. Current treatment strategies for osteoporotic vertebral compression fractures (VCFs) focus on cement-associated solutions. Complications associated with cement application are leakage, embolism, adjacent fractures, and compromise in bony healing. This study comprises a validated VCF model in osteoporotic sheep in order to (1) evaluate a new cementless fracture fixation technique using titanium mesh implants (TMIs) and (2) demonstrate the healing capabilities in osteoporotic VCFs. Methods. Twelve 5-year-old Merino sheep received ovariectomy, corticosteroid injections, and a calcium/phosphorus/vitamin D-deficient diet for osteoporosis induction. Standardized VCFs (type AO A3.1) were created, reduced, and fixed using intravertebral TMIs. Randomly additional autologous spongiosa grafting (G1) or no augmentation was performed (G2, n = 6 each). Two months postoperatively, macroscopic, micro-CT and biomechanical evaluation assessed bony consolidation. Results. Fracture reduction succeeded in all cases without intraoperative complications. Bony consolidation was proven for all cases with increased amounts of callus development for G2 (58.3%). Micro-CT revealed cage integration. Neither group showed improved results with biomechanical testing. Conclusions. Fracture reduction/fixation using TMIs without cement in osteoporotic sheep lumbar VCF resulted in bony fracture healing. Intravertebral application of autologous spongiosa showed no beneficial effects. The technique is now available for clinical use; thus, it offers an opportunity to abandon cement-associated complications. PMID:27019848

  1. The paediatric wrist revisited - findings of bony depressions in healthy children on radiographs compared to MRI

    Energy Technology Data Exchange (ETDEWEB)

    Avenarius, Derk M.F.; Eldevik, Petter [University Hospital North Norway, Department of Radiology, Tromsoe (Norway); Ording Mueller, Lil-Sofie [University Hospital North Norway, Department of Radiology, Tromsoe (Norway); Great Ormond Street Hospital for Children, Department of Radiology, London (United Kingdom); Owens, Catherine M. [Great Ormond Street Hospital for Children, Department of Radiology, London (United Kingdom); University College London, Institute of Child Health, London (United Kingdom); Rosendahl, Karen [Haukeland University Hospital, Department of Radiology, Bergen (Norway); University of Bergen, Department of Surgical Sciences, Bergen (Norway); Great Ormond Street Hospital for Children, Department of Radiology, London (United Kingdom)

    2012-07-15

    The presence of erosions is used for diagnosis and monitoring of disease activity in juvenile idiopathic arthritis (JIA). Assessment of carpal bone erosions in children is challenging due to lack of normal references. To define normal appearances of bony depressions in the wrist on radiographs and MRI. MRI and radiography of the wrist were performed in 88 healthy children, 5-15 years of age. We assessed the number of bony depressions within the carpals/proximal metacarpals on both modalities, separately and combined. A total of 75 carpal depressions were identified on radiography compared to 715 on MRI. The number of bony depressions identified radiographically showed no statistically significant difference across age-groups. Within the metacarpals, there was no significant difference between bony depressions identified by MRI or radiography, except at the bases of the second metacarpal. Bony depressions that resemble erosions are normal findings in the wrist in children. MRI identifies more depressions than radiographs in the carpus. Some bony depressions occur at typical locations and should be accounted for when assessing the wrist in JIA to avoid overstaging. (orig.)

  2. The paediatric wrist revisited - findings of bony depressions in healthy children on radiographs compared to MRI

    International Nuclear Information System (INIS)

    The presence of erosions is used for diagnosis and monitoring of disease activity in juvenile idiopathic arthritis (JIA). Assessment of carpal bone erosions in children is challenging due to lack of normal references. To define normal appearances of bony depressions in the wrist on radiographs and MRI. MRI and radiography of the wrist were performed in 88 healthy children, 5-15 years of age. We assessed the number of bony depressions within the carpals/proximal metacarpals on both modalities, separately and combined. A total of 75 carpal depressions were identified on radiography compared to 715 on MRI. The number of bony depressions identified radiographically showed no statistically significant difference across age-groups. Within the metacarpals, there was no significant difference between bony depressions identified by MRI or radiography, except at the bases of the second metacarpal. Bony depressions that resemble erosions are normal findings in the wrist in children. MRI identifies more depressions than radiographs in the carpus. Some bony depressions occur at typical locations and should be accounted for when assessing the wrist in JIA to avoid overstaging. (orig.)

  3. Vaccination Games with Peer Effects in a Heterogeneous Hospital Worker Population

    Directory of Open Access Journals (Sweden)

    Troy Tassier

    2015-01-01

    Full Text Available We develop a game theoretic model to analyze the Nash equilibrium of vaccine decisions in a hospital population with heterogeneous contacts. We use the model in conjunction with person-to-person contact data within a large university hospital. We simulate, using agent-based models, the probability of infection for various worker types in the data and use these probabilities to identify the Nash equilibrium vaccine choices of hospital workers. The analysis suggests that there may be large differences in vaccination rates among hospital worker groups. We extend the model to include peer effects within the game. The peer effects may create additional equilibria or may further cement existing equilibria depending on parameter values. Further, depending on the magnitude of the peer effects and the costs of infection and vaccination, peer effects may increase or decrease differences in worker group vaccination rates within the hospital.

  4. Effects of heterogeneity on recrystallization kinetics of nanocrystalline copper prepared by dynamic plastic deformation

    DEFF Research Database (Denmark)

    Lin, Fengxiang; Zhang, Yubin; Tao, Nairong;

    2014-01-01

    develop a heterogeneous structure, consisting of regions with different textures and microstructures. This heterogeneity within the deformed structure leads to the formation of severely clustered grains in partially recrystallized samples. The recrystallization kinetic curve shows an Avrami exponent less...

  5. Effects of heterogeneous traffic with speed limit zone on the car accidents

    Science.gov (United States)

    Marzoug, R.; Lakouari, N.; Bentaleb, K.; Ez-Zahraouy, H.; Benyoussef, A.

    2016-06-01

    Using the extended Nagel-Schreckenberg (NS) model, we numerically study the impact of the heterogeneity of traffic with speed limit zone (SLZ) on the probability of occurrence of car accidents (Pac). SLZ in the heterogeneous traffic has an important effect, typically in the mixture velocities case. In the deterministic case, SLZ leads to the appearance of car accidents even in the low densities, in this region Pac increases with increasing of fraction of fast vehicles (Ff). In the nondeterministic case, SLZ decreases the effect of braking probability Pb in the low densities. Furthermore, the impact of multi-SLZ on the probability Pac is also studied. In contrast with the homogeneous case [X. Li, H. Kuang, Y. Fan and G. Zhang, Int. J. Mod. Phys. C 25 (2014) 1450036], it is found that in the low densities the probability Pac without SLZ (n = 0) is low than Pac with multi-SLZ (n > 0). However, the existence of multi-SLZ in the road decreases the risk of collision in the congestion phase.

  6. Effects of temperature on the heterogeneous oxidation of sulfur dioxide by ozone on calcium carbonate

    Directory of Open Access Journals (Sweden)

    L. Y. Wu

    2011-01-01

    Full Text Available The heterogeneous oxidations of sulfur dioxide by ozone on CaCO3 were studied as a function of temperature (230 to 298 K at ambient pressure. Oxidation reactions were followed in real time using diffuse reflectance infrared Fourier transform spectrometry (DRIFTS to obtain kinetics and mechanistic data. From the analysis of the spectral features, the formation of sulfate was identified on the surface in the presence of O3 and SO2 at different temperatures from 230 to 298 K. The results showed that the heterogeneous oxidations and the rate of sulfate formation were sensitive to temperature. An interesting stage-transition state was observed at temperatures range from 230 to 257 K, but it became ambiguous gradually above 257 K. The reactive uptake coefficients at different temperatures from 230 to 298 K were acquired for the first time, which can be used directly in the model studies to predict the formation of secondary sulfate aerosol in the troposphere. Furthermore, the rate of sulfate formation had a turning point at about 250 K. The sulfate concentration at 250 K was about twice as large as that at 298 K. The rate of sulfate formation increased with decreasing temperature at temperatures above 250 K, while there is a contrary temperature effect at temperatures below 250 K. The activation energy for heterogeneous oxidations at temperatures from 245 K to 230 K was determined to be 14.63 ± 0.20 kJ mol−1. Mechanism of temperature dependence was proposed and the atmospheric implications were discussed.

  7. Effects of temperature on the heterogeneous oxidation of sulfur dioxide by ozone on calcium carbonate

    Directory of Open Access Journals (Sweden)

    L. Y. Wu

    2011-07-01

    Full Text Available The heterogeneous oxidation of sulfur dioxide by ozone on CaCO3 was studied as a function of temperature (230 to 298 K at ambient pressure. Oxidation reactions were followed in real time using diffuse reflectance infrared Fourier transform spectrometry (DRIFTS to obtain kinetic and mechanistic data. From the analysis of the spectral features, the formation of sulfate was identified on the surface in the presence of O3 and SO2 at different temperatures from 230 to 298 K. The results showed that the heterogeneous oxidation and the rate of sulfate formation were sensitive to temperature. An interesting stage-transition region was observed at temperatures ranging from 230 to 257 K, but it became ambiguous gradually above 257 K. The reactive uptake coefficients at different temperatures from 230 to 298 K were acquired for the first time, which can be used directly in atmospheric chemistry modeling studies to predict the formation of secondary sulfate aerosol in the troposphere. Furthermore, the rate of sulfate formation had a turning point at about 250 K. The sulfate concentration at 250 K was about twice as large as that at 298 K. The rate of sulfate formation increased with decreasing temperature at temperatures above 250 K, while there is a contrary temperature effect at temperatures below 250 K. The activation energy for heterogeneous oxidation at temperatures from 245 K to 230 K was determined to be 14.63 ± 0.20 kJ mol−1. A mechanism for the temperature dependence was proposed and the atmospheric implications were discussed.

  8. The effect of organic coating on the heterogeneous ice nucleation efficiency of mineral dust aerosols

    International Nuclear Information System (INIS)

    The effect of organic coating on the heterogeneous ice nucleation (IN) efficiency of dust particles was investigated at simulated cirrus cloud conditions in the AIDA cloud chamber of Forschungszentrum Karlsruhe. Arizona test dust (ATD) and the clay mineral illite were used as surrogates for atmospheric dust aerosols. The dry dust samples were dispersed into a 3.7 m3 aerosol vessel and either directly transferred into the 84 m3 cloud simulation chamber or coated before with the semi-volatile products from the reaction of α-pinene with ozone in order to mimic the coating of atmospheric dust particles with secondary organic aerosol (SOA) substances. The ice-active fraction was measured in AIDA expansion cooling experiments as a function of the relative humidity with respect to ice, RHi, in the temperature range from 205 to 210 K. Almost all uncoated dust particles with diameters between 0.1 and 1.0 μm acted as efficient deposition mode ice nuclei at RHi between 105 and 120%. This high ice nucleation efficiency was markedly suppressed by coating with SOA. About 20% of the ATD particles coated with a SOA mass fraction of 17 wt% were ice-active at RHi between 115 and 130%, and only 10% of the illite particles coated with an SOA mass fraction of 41 wt% were ice-active at RHi between 160 and 170%. Only a minor fraction of pure SOA particles were ice-active at RHi between 150 and 190%. Strong IN activation of SOA particles was observed only at RHi above 200%, which is clearly above water saturation at the given temperature. The IN suppression and the shift of the heterogeneous IN onset to higher RHi seem to depend on the coating thickness or the fractional surface coverage of the mineral particles. The results indicate that the heterogeneous ice nucleation potential of atmospheric mineral particles may also be suppressed if they are coated with secondary organics

  9. Numerical determination of micro-forming limit diagrams: introduction of the effect of grain size heterogeneity

    International Nuclear Information System (INIS)

    This paper presents the determination of virtual micro-forming limit diagrams by a behaviour law adapted to thin materials introducing the effect of microstructure heterogeneity. The observed size effect, i.e. the decrease in flow stress when the grain size increased, was modelled by a specific phenomenological behaviour law. A reduced numerical simulation by a finite element method rendered it possible to carry out very fast simulations of the different modes of deformation and to determine the virtual micro-forming limit diagrams from the onset of necking. This methodology was compared with experimental results on aluminium 1050A (99.5%) of thickness 0.2 mm. The comparison of the experimental and numerical data demonstrated good agreement between the real and virtual results obtained by such a methodology. (paper)

  10. Surface heterogeneity effects of activated carbons on the kinetics of paracetamol removal from aqueous solution

    Science.gov (United States)

    Ruiz, B.; Cabrita, I.; Mestre, A. S.; Parra, J. B.; Pires, J.; Carvalho, A. P.; Ania, C. O.

    2010-06-01

    The removal of a compound with therapeutic activity (paracetamol) from aqueous solutions using chemically modified activated carbons has been investigated. The chemical nature of the activated carbon material was modified by wet oxidation, so as to study the effect of the carbon surface chemistry and composition on the removal of paracetamol. The surface heterogeneity of the carbon created upon oxidation was found to be a determinant in the adsorption capability of the modified adsorbents, as well as in the rate of paracetamol removal. The experimental kinetic data were fitted to the pseudo-second order and intraparticle diffusion models. The parameters obtained were linked to the textural and chemical features of the activated carbons. After oxidation the wettability of the carbon is enhanced, which favors the transfer of paracetamol molecules to the carbon pores (smaller boundary layer thickness). At the same time the overall adsorption rate and removal efficiency are reduced in the oxidized carbon due to the competitive effect of water molecules.

  11. Pore and Continuum Scale Study of the Effect of Subgrid Transport Heterogeneity on Redox Reaction Rates

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yuanyuan; Liu, Chongxuan; Zhang, Changyong; Yang, Xiaofan; Zachara, John M.

    2015-08-01

    A micromodel system with a pore structure for heterogeneous flow and transport was used to investigate the effect of subgrid transport heterogeneity on redox reaction rates. Hematite reductive dissolution by injecting a reduced form of flavin mononucleotide (FMNH2) at variable flow rates was used as an example to probe the variations of redox reaction rates in different subgrid transport domains. Experiments, pore-scale simulations, and macroscopic modeling were performed to measure and simulate in-situ hematite reduction and to evaluate the scaling behavior of the redox reaction rates from the pore to macroscopic scales. The results indicated that the measured pore-scale rates of hematite reduction were consistent with the predictions from a pore scale reactive transport model. A general trend is that hematite reduction followed reductant transport pathways, starting from the advection-dominated pores toward the interior of diffusion-dominated domains. Two types of diffusion domains were considered in the micromodel: a micropore diffusion domain, which locates inside solid grains or aggregates where reactant transport is limited by diffusion; and a macropore diffusion domain, which locates at wedged, dead-end pore spaces created by the grain-grain contacts. The rate of hematite reduction in the advection-dominated domain was faster than those in the diffusion-controlled domains, and the rate in the macropore diffusion domain was faster than that in the micropore domain. The reduction rates in the advection and macropore diffusion domains increased with increasing flow rate, but were affected by different mechanisms. The rate increase in the advection domain was controlled by the mass action effect as a faster flow supplied more reactants, and the rate increase in the macropore domain was more affected by the rate of mass exchange with the advection domain, which increased with increasing flow rate. The hematite reduction rate in the micropore domain was, however

  12. Effect of Heterogeneous Transmission Rate on Epidemic Spreading Over Scale Free Networks

    CERN Document Server

    Sagar, Vikram

    2016-01-01

    In the present work the spread of epidemic is studied over complex networks which are characterized by power law degree distribution of links and heterogeneous rate of disease transmission. The random allocation of epidemic transmission rates to the nodes results in the heterogeneity, which in turn causes the segregation of nodes in terms of various sub populations. The aim of the study is to gain microscopic insight into the effect of interactions among various sub populations in the spreading processes of disease over such networks. The discrete time Markov chain method based upon the susceptible infected susceptible (SIS) model of diseases transmission has been used to describe the spreading of epidemic over the networks. The study is parameterized in terms of variable $\\lambda$, defined as the number of contacts a node makes with the fraction of its neighboring nodes. From the simulation results, it is found that the spread of epidemic on such networks is critical in terms of number of minimum contacts ma...

  13. Nanoparticle-enhanced spectral photoacoustic tomography: effect of oxygen saturation and tissue heterogeneity

    Science.gov (United States)

    Vogt, William C.; Jia, Congxian; Wear, Keith A.; Garra, Brian S.; Pfefer, T. Joshua

    2016-03-01

    Molecular imaging for breast cancer detection, infectious disease diagnostics and preclinical animal research may be achievable through combined use of targeted exogenous agents - such as nanoparticles - and spectral Photoacoustic Tomography (PAT). However, tissue heterogeneity can alter fluence distributions and acoustic propagation, corrupting measured PAT absorption spectra and complicating in vivo nanoparticle detection and quantitation. Highly absorptive vascular structures represent a common confounding factor, and variations in vessel hemoglobin saturation (SO2) may alter spectral content of signals from adjacent/deeper regions. To evaluate the impact of this effect on PAT nanoparticle detectability, we constructed heterogeneous phantoms with well-characterized channel-inclusion geometries and biologically relevant optical and acoustic properties. Phantoms contained an array of tubes at several depths filled with hemoglobin solutions doped with varying concentrations of gold nanorods with an absorption peak at 780 nm. Both overlying and target network SO2 was tuned using sodium dithionite. Phantoms were imaged from 700 to 900 nm using a custom PAT system comprised of a tunable pulsed laser and a research-grade ultrasound system. Recovered nanoparticle spectra were analyzed and compared with results from both spectrophotometry and PAT data from waterimmersed tubes containing blood and nanoparticle solutions. Results suggested that nanoparticle selection for a given PAT application should take into account expected oxygenation states of both target blood vessel and background tissue oxygenation to achieve optimal performance.

  14. Soil heterogeneity effects on water and solute transport. Methodological comparison in different climates

    Energy Technology Data Exchange (ETDEWEB)

    Yasuda, Hiroshi

    1996-11-01

    Spatial heterogeneity of soils is important to consider for soil water and solute transport. The results of the present work indicated that spatial heterogeneity affects all investigated soils and for widely varying climates. Both soil water content and temperature patterns for a bare and vegetated transect in a typical sand dune area in China indicated preferential transport of soil water after rainfall. Infiltrating soil water appeared to follow paths that had high water content before the rainfall. The effect of rainfall was therefore not a larger uniformity of soil water, but rather increasing variability. Preferential flow was observed by tracer and dye in Tunisia. The experimental data indicated a high degree of bypass or preferential flow within small plots and non-sigmoid breakthrough curves suggesting tailing phenomena and immobile fractions of soil water. The groundwater tracer concentration increased up to twice the concentration of the water in the unsaturated zone withdrawn from different depths. This consequently shows that bypass directly to the groundwater occurred also for unsaturated conditions. Soil layering appeared to be a significant cause for preferential flow for both sand and clay soils. The results also showed great variability for hydraulic properties in terms of van Genuchten parameters for a small plot in a temperate climate. The present work supports the dual-porosity hypothesis. But findings also indicate that the observation scale is important to consider when averaging the process in time and space. 95 refs, 7 figs, 1 tab

  15. Mixing effects on apparent reaction rates and isotope fractionation during denitrification in a heterogeneous aquifer

    Science.gov (United States)

    Green, C.T.; Böhlke, J.K.; Bekins, B.A.; Phillips, S.P.

    2010-01-01

    Gradients in contaminant concentrations and isotopic compositions commonly are used to derive reaction parameters for natural attenuation in aquifers. Differences between field-scale (apparent) estimated reaction rates and isotopic fractionations and local-scale (intrinsic) effects are poorly understood for complex natural systems. For a heterogeneous alluvial fan aquifer, numerical models and field observations were used to study the effects of physical heterogeneity on reaction parameter estimates. Field measurements included major ions, age tracers, stable isotopes, and dissolved gases. Parameters were estimated for the O2 reduction rate, denitrification rate, O 2 threshold for denitrification, and stable N isotope fractionation during denitrification. For multiple geostatistical realizations of the aquifer, inverse modeling was used to establish reactive transport simulations that were consistent with field observations and served as a basis for numerical experiments to compare sample-based estimates of "apparent" parameters with "true" (intrinsic) values. For this aquifer, non-Gaussian dispersion reduced the magnitudes of apparent reaction rates and isotope fractionations to a greater extent than Gaussian mixing alone. Apparent and true rate constants and fractionation parameters can differ by an order of magnitude or more, especially for samples subject to slow transport, long travel times, or rapid reactions. The effect of mixing on apparent N isotope fractionation potentially explains differences between previous laboratory and field estimates. Similarly, predicted effects on apparent O2 threshold values for denitrification are consistent with previous reports of higher values in aquifers than in the laboratory. These results show that hydrogeological complexity substantially influences the interpretation and prediction of reactive transport. ?? 2010 by the American Geophysical Union.

  16. Distance-to-Agreement Investigation of Tomotherapy's Bony Anatomy-Based Autoregistration and Planning Target Volume Contour-Based Optimization

    International Nuclear Information System (INIS)

    Purpose: To compare Tomotherapy's megavoltage computed tomography bony anatomy autoregistration with the best achievable registration, assuming no deformation and perfect knowledge of planning target volume (PTV) location. Methods and Materials: Distance-to-agreement (DTA) of the PTV was determined by applying a rigid-body shift to the PTV region of interest of the prostate from its reference position, assuming no deformations. Planning target volume region of interest of the prostate was extracted from the patient archives. The reference position was set by the 6 degrees of freedom (dof)—x, y, z, roll, pitch, and yaw—optimization results from the previous study at this institution. The DTA and the compensating parameters were calculated by the shift of the PTV from the reference 6-dof to the 4-dof—x, y, z, and roll—optimization. In this study, the effectiveness of Tomotherapy's 4-dof bony anatomy–based autoregistration was compared with the idealized 4-dof PTV contour-based optimization. Results: The maximum DTA (maxDTA) of the bony anatomy-based autoregistration was 3.2 ± 1.9 mm, with the maximum value of 8.0 mm. The maxDTA of the contour-based optimization was 1.8 ± 1.3 mm, with the maximum value of 5.7 mm. Comparison of Pearson correlation of the compensating parameters between the 2 4-dof optimization algorithms shows that there is a small but statistically significant correlation in y and z (0.236 and 0.300, respectively), whereas there is very weak correlation in x and roll (0.062 and 0.025, respectively). Conclusions: We find that there is an average improvement of approximately 1 mm in terms of maxDTA on the PTV going from 4-dof bony anatomy-based autoregistration to the 4-dof contour-based optimization. Pearson correlation analysis of the 2 4-dof optimizations suggests that uncertainties due to deformation and inadequate resolution account for much of the compensating parameters, but pitch variation also makes a statistically significant

  17. Effect of low-density heterogeneities in telecobalt therapy and validation of dose calculation algorithm of a treatment planning system

    International Nuclear Information System (INIS)

    Telecobalt machines are still prominently used for the treatment of a variety of cancer cases in developing countries. The human body is a heterogeneous composition of variety of tissues and cavities which vary widely in their physical and radiological properties. The presence of heterogeneities in the path of telecobalt beam presents an altered dose distribution in the region of clinical interests. A computerized treatment planning system (TPS) is generally used for calculating the dose distribution in the patient. Experimental measurements were carried out in a telecobalt beam with the objectives to study the effects of low-density heterogeneities and to verify the ability of the ASHA radiotherapy TPS in predicting the altered dose distribution along the central axis and off-axis of the beam. Locally available kailwood was tested for its lung equivalence and measurements were carried out in a polymethyl methacrylate phantom by introducing lung equivalent and air gap heterogeneities. A comparison of experimentally measured and TPS calculated dose values indicates that the TPS overestimates the dose by 11.6% in lung equivalent (kailwood) heterogeneity along the central axis. Similarly, it was found that the TPS overestimates the dose by 3.9% and 5.9%, respectively, with air heterogeneity of 1.0 and 2.0 cm. While testing the adequacy of TPS in off-axis region, it was found that the TPS calculation does not indicate the widening of the beam profile in the low-density heterogeneity region. This study suggests that the effective path length based algorithm of the ASHA radiotherapy TPS is unable to achieve the recommended 3% accuracy of clinical dose calculation in heterogeneous media. (author)

  18. Bony labyrinth shape variation in extant Carnivora: a case study of Musteloidea.

    Science.gov (United States)

    Grohé, Camille; Tseng, Z Jack; Lebrun, Renaud; Boistel, Renaud; Flynn, John J

    2016-03-01

    The bony labyrinth provides a proxy for the morphology of the inner ear, a primary cognitive organ involved in hearing, body perception in space, and balance in vertebrates. Bony labyrinth shape variations often are attributed to phylogenetic and ecological factors. Here we use three-dimensional (3D) geometric morphometrics to examine the phylogenetic and ecological patterns of variation in the bony labyrinth morphology of the most species-rich and ecologically diversified traditionally recognized superfamily of Carnivora, the Musteloidea (e.g. weasels, otters, badgers, red panda, skunks, raccoons, coatis). We scanned the basicrania of specimens belonging to 31 species using high-resolution X-ray computed micro-tomography (μCT) to virtually reconstruct 3D models of the bony labyrinths. Labyrinth morphology is captured by a set of six fixed landmarks on the vestibular and cochlear systems, and 120 sliding semilandmarks, slid at the center of the semicircular canals and the cochlea. We found that the morphology of this sensory structure is not significantly influenced by bony labyrinth size, in comparisons across all musteloids or in any of the individual traditionally recognized families (Mephitidae, Procyonidae, Mustelidae). PCA (principal components analysis) of shape data revealed that bony labyrinth morphology is clearly distinguishable between musteloid families, and permutation tests of the Kmult statistic confirmed that the bony labyrinth shows a phylogenetic signal in musteloids and in most mustelids. Both the vestibular and cochlear regions display morphological differences among the musteloids sampled, associated with the size and curvature of the semicircular canals, angles between canals, presence or absence of a secondary common crus, degree of lateral compression of the vestibule, orientation of the cochlea relative to the semicircular canals, proportions of the cochlea, and degree of curvature of its turns. We detected a significant ecological signal

  19. Volumetric Changes in the Bony External Auditory Canal in Unilateral Chronic Otitis Media

    Science.gov (United States)

    Park, Jae Hong; Noh, MinHo; Park, Seung Bum; Park, Kye Hoon; Han, Jong Kyu; Kim, Hyun Jeong

    2016-01-01

    Background and Objectives Pneumatization of air cells in the mastoid bone is decreased in chronic otitis media (COM). A decrease in the size of the external auditory canal (EAC) is also found frequently in patients with COM, but this has been little studied. We compared the size of affected bony EACs and the contralateral side in patients with single-side COM using high-resolution computed tomography. Subjects and Methods In total, 99 patients with single-side COM were included. Four indicators related to the size of the bony EAC and IAC were measured using high-resolution computed tomography: the axial and coronal lengths of the tympanic membrane, the length of the isthmus, and the area of the bony ear canal. We also compared both internal auditory canals as negative controls. These assessments were made by radiologists who were blinded to the objective of this study. Results In patients with single-side COM, the axial length of the tympanic membrane was significantly shorter than normal, and the volume of the EAC was also significantly smaller. The length of the isthmus of the EAC was shorter on the affected side, but the difference was not significant. The IAC volume showed no difference between the two sides. Conclusions COM affects general temporal bony development, including the bony EAC and mastoid bone. Therefore, whether to correct this should be considered when preparing for COM surgery. PMID:27144233

  20. Effects of vegetation heterogeneity and surface topography on spatial scaling of net primary productivity

    Directory of Open Access Journals (Sweden)

    J. M. Chen

    2013-03-01

    Full Text Available Due to the heterogeneous nature of the land surface, spatial scaling is an inevitable issue in the development of land models coupled with low-resolution Earth system models (ESMs for predicting land-atmosphere interactions and carbon-climate feedbacks. In this study, a simple spatial scaling algorithm is developed to correct errors in net primary productivity (NPP estimates made at a coarse spatial resolution based on sub-pixel information of vegetation heterogeneity and surface topography. An eco-hydrological model BEPS-TerrainLab, which considers both vegetation and topographical effects on the vertical and lateral water flows and the carbon cycle, is used to simulate NPP at 30 m and 1 km resolutions for a 5700 km2 watershed with an elevation range from 518 m to 3767 m in the Qinling Mountain, Shaanxi Province, China. Assuming that the NPP simulated at 30 m resolution represents the reality and that at 1 km resolution is subject to errors due to sub-pixel heterogeneity, a spatial scaling index (SSI is developed to correct the coarse resolution NPP values pixel by pixel. The agreement between the NPP values at these two resolutions is improved considerably from R2 = 0.782 to R2 = 0.884 after the correction. The mean bias error (MBE in NPP modeled at the 1 km resolution is reduced from 14.8 g C m−2 yr−1 to 4.8 g C m−2 yr−1 in comparison with NPP modeled at 30 m resolution, where the mean NPP is 668 g C m−2 yr−1. The range of spatial variations of NPP at 30 m resolution is larger than that at 1 km resolution. Land cover fraction is the most important vegetation factor to be considered in NPP spatial scaling, and slope is the most important topographical factor for NPP spatial scaling especially in mountainous areas, because of its influence on the lateral water redistribution, affecting water table, soil moisture and plant growth. Other factors including leaf area index (LAI, elevation and aspect have small and additive effects on

  1. Sensitivity of Effective Thermal Conductivity Models on Temperature Distribution of Heterogeneous media of Fully Ceramic Micro-encapsulated Fuel

    International Nuclear Information System (INIS)

    A TRISO fuel particle consists of a spherical fuel kernel with four coating layers such as buffer, Inner PyC, SiC, Outer PyC. A FCM fuel pellet contains randomly distributed 36 in a SiC matrix. Such heterogeneous and complicated structure adds difficulty in calculating the realistic temperature distributions in the FCM fuel. General practice is to use a homogenized model using an effective thermal conductivity model. For these difficulties, a realistic temperature profile on a heterogeneous media is generally calculated on a homogenization model. In this study, we investigate the influence of effective thermal conductivity models on the temperature distribution in a heterogeneous media on FCM fuel pellet. Feasibility of Single Domain Homogenization(SDH) model has been estimated for a heterogeneous media like FCM fuel. From the study, it is found that the effective thermal conductivity is a crucial parameter in analyzing the temperature distributions in SDH approach. Sensitivity of the effective thermal conductivity models indicates that the Maxwell model or an optimized conductivity models are adequate in modeling the heterogeneous FCM fuel

  2. Heterogeneous reactivity effects in medium- and high-enriched uranium metal-water systems

    International Nuclear Information System (INIS)

    The effect of heterogeneity on reactivity of low-, medium-, and high-enriched, water-moderated uranium metal systems has been examined for various hydrogen-to-fissile (H/X) ratios using the CSAS1X sequence in SCALE and MCNP. For the calculations, an infinite array of close-packed unit cells was modeled which consisted of centered uranium metal spheres surrounded by water. The enrichments used correspond to the average enrichments of fragmented fuel plates in three proposed waste shipments from Oak Ridge National Laboratory. The analysis performed to obtain peak reactivity for each enrichment as a function of particle size and H/X ratio led to the development of the topic discussed in this paper

  3. Prisoner's Dilemma Game with Heterogeneous Influential Effect on Regular Small-World Networks

    Institute of Scientific and Technical Information of China (English)

    WU Zhi-Xi; XU Xin-Jian; WANG Ying-Hai

    2006-01-01

    @@ The effect of heterogeneous influence of different individuals on the maintenance of co-operative behaviour is studied in an evolutionary Prisoner's Dilemma game with players located on the sites of regular small-world networks. The players interacting with their neighbours can either co-operate or defect and update their states by choosing one of the neighbours and adopting its strategy with a probability depending on the payoff difference.The selection of the neighbour obeys a preferential rule: the more influential a neighbour, the larger the probability it is picked. It is found that this simple preferential selection rule can promote continuously the co-operation of the whole population with the strengthening of the disorder of the underlying network.

  4. Modeling the Effects of Node Heterogeneity on the Performance of Grid Applications

    Directory of Open Access Journals (Sweden)

    Paolo Cremonesi

    2009-11-01

    Full Text Available The performance benefit when using grid systems comes from different strategies, among which partitioning the applications into parallel tasks is the most important. However, in most cases the enhancement coming from partitioning is smoothed by the effects of synchronization overheads, mainly due to the high variability in the execution times of the different tasks, which, in turn, is accentuated by the large heterogeneity of grid nodes. In this paper we design hierarchical, queuing network performance models able to accurately analyze grid architectures and applications. Thanks to the model results, we introduce a new allocation policy based on a combination between task partitioning and task replication. The models are used to study two real applications and to evaluate the performance benefits obtained with allocation policies based on task replication.

  5. The Effect of Heterogeneity on Rock's Ultrasonic Attenuation and Its Correction

    Institute of Scientific and Technical Information of China (English)

    Wang Baoshan; Sun Daoyuan; Li Shengjie; Li Weidong; Shi Xingjue; Liu Bin

    2001-01-01

    The effect of Rayleigh scatter caused by the heterogeneity of rocks, on attenuation measurement has been considered adequately. According to the related theory and calculation, we can distinguish the intrinsic attenuation from the scattering attenuation. And we amended the classic spectral ratio method, based on the homogeneous medium hypothesis. Using the improved spectral ratio method, we can obtain Q value within a wider frequency range, so we can eliminate the uncertainty condition in classic spectral ratio, where Q value depends on the frequency range. The frequency shift method has been introduced and improved. Those three methods on one set of data had been applied. The results obtained by using the classic and improved spectral ratio and frequency shift methods fit well.

  6. Allocating Sample Sizes to Reduce Budget for Fixed-Effect 2×2 Heterogeneous Analysis of Variance

    Science.gov (United States)

    Luh, Wei-Ming; Guo, Jiin-Huarng

    2016-01-01

    This article discusses the sample size requirements for the interaction, row, and column effects, respectively, by forming a linear contrast for a 2×2 factorial design for fixed-effects heterogeneous analysis of variance. The proposed method uses the Welch t test and its corresponding degrees of freedom to calculate the final sample size in a…

  7. Severe bony ankylosis of the temporomandibular joint on one side and contralateral adhesion: A case report

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ji Young [Dept. of Oral and Maxillofacial Surgery, Jeju National University Hospital, Jeju National University School of Medicine, Jeju (Korea, Republic of); Kim, Seong Gon; Choi, Hang Moon [School of Dentistry, Gangneung-Wonju National University, Gangneung (Korea, Republic of); Kim, Hyun Jung [Dept. of Anesthesiology and Pain Medicine, Jeju National University School of Medicine, Jeju (Korea, Republic of)

    2015-06-15

    Bony fusion between the mandibular condyle and skull base involves temporomandibular joint (TMJ) bony ankylosis. This condition might originate from trauma, infection, or systemic disease. TMJ adhesion can develop after synovial damage. Both TMJ ankylosis and adhesion lead to functional impairment and pain. Here, we present a case of a 50-year-old female who had bony ankylosis of the right TMJ and adhesion of the left TMJ. She had otitis media in the right ear. A large mass in the right TMJ was observed on computed tomograph. Magnetic resonance image showed a large fused bone mass with normal bone marrow in the right TMJ and flattening of the condyle with a thin disk in the left TMJ. Gap arthroplasty with temporal fascia was performed on the right TMJ, and discectomy, high condylectomy, and coronoidectomy were performed on the left TMJ. During a 2-year follow-up after surgery, the patient had no recurrence.

  8. Epidermal cyst of the bony external auditory canal in an adult

    Directory of Open Access Journals (Sweden)

    Ihshan Ali

    2012-01-01

    Full Text Available To present a rare case of epidermal cyst of the bony external auditory canal (EAC in an adult. Epidermal cyst of the bony EAC, although very rare, should be kept in the list of differential diagnosis of a skin-lined mass of the EAC. Epidermal cyst is very rare in the EAC. Only two cases of epidermoid cyst arising from the bony EAC are reported previously in English, but both were in pediatric age group. Epidermal cyst in EAC in adult patients may be confused with masses that are commonly seen, and these include osteomas, exostosis, ear polyps, carcinomas, etc. Epidermal cyst should be included in the differential diagnosis of a patient with an ear mass.

  9. Severe bony ankylosis of the temporomandibular joint on one side and contralateral adhesion: A case report

    International Nuclear Information System (INIS)

    Bony fusion between the mandibular condyle and skull base involves temporomandibular joint (TMJ) bony ankylosis. This condition might originate from trauma, infection, or systemic disease. TMJ adhesion can develop after synovial damage. Both TMJ ankylosis and adhesion lead to functional impairment and pain. Here, we present a case of a 50-year-old female who had bony ankylosis of the right TMJ and adhesion of the left TMJ. She had otitis media in the right ear. A large mass in the right TMJ was observed on computed tomograph. Magnetic resonance image showed a large fused bone mass with normal bone marrow in the right TMJ and flattening of the condyle with a thin disk in the left TMJ. Gap arthroplasty with temporal fascia was performed on the right TMJ, and discectomy, high condylectomy, and coronoidectomy were performed on the left TMJ. During a 2-year follow-up after surgery, the patient had no recurrence

  10. Effect of heterogeneity on enhanced reductive dechlorination: Analysis of remediation efficiency and groundwater acidification

    Science.gov (United States)

    Brovelli, A.; Lacroix, E.; Robinson, C. E.; Gerhard, J.; Holliger, C.; Barry, D. A.

    2011-12-01

    Enhanced reductive dehalogenation is an attractive in situ treatment technology for chlorinated contaminants. The process includes two acid-forming microbial reactions: fermentation of an organic substrate resulting in short-chain fatty acids, and dehalogenation resulting in hydrochloric acid. The accumulation of acids and the resulting drop of groundwater pH are controlled by the mass and distribution of chlorinated solvents in the source zone, type of electron donor, alternative terminal electron acceptors available and presence of soil mineral phases able to buffer the pH (such as carbonates). Groundwater acidification may reduce or halt microbial activity, and thus dehalogenation, significantly increasing the time and costs required to remediate the aquifer. In previous work a detailed geochemical and groundwater flow simulator able to model the fermentation-dechlorination reactions and associated pH change was developed. The model accounts for the main processes influencing microbial activity and groundwater pH, including the groundwater composition, the electron donor used and soil mineral phase interactions. In this study, the model was applied to investigate how spatial variability occurring at the field scale affects dechlorination rates, groundwater pH and ultimately the remediation efficiency. Numerical simulations were conducted to examine the influence of heterogeneous hydraulic conductivity on the distribution of the injected, fermentable substrate and on the accumulation/dilution of the acidic products of reductive dehalogenation. The influence of the geometry of the DNAPL source zone was studied, as well as the spatial distribution of soil minerals. The results of this study showed that the heterogeneous distribution of the soil properties have a potentially large effect on the remediation efficiency. For examples, zones of high hydraulic conductivity can prevent the accumulation of acids and alleviate the problem of groundwater acidification. The

  11. Serological markers suggest heterogeneity of effectiveness of malaria control interventions on Bioko Island, equatorial Guinea.

    Directory of Open Access Journals (Sweden)

    Jackie Cook

    Full Text Available BACKGROUND: In order to control and eliminate malaria, areas of on-going transmission need to be identified and targeted for malaria control interventions. Immediately following intense interventions, malaria transmission can become more heterogeneous if interventions are more successful in some areas than others. Bioko Island, Equatorial Guinea, has been subject to comprehensive malaria control interventions since 2004. This has resulted in substantial reductions in the parasite burden, although this drop has not been uniform across the island. METHODS/PRINCIPAL FINDINGS: In 2008, filter paper blood samples were collected from 7387 people in a cross-sectional study incorporating 18 sentinel sites across Bioko, Equatorial Guinea. Antibodies were measured to P. falciparum Apical Membrane Antigen-1 (AMA-1 by Enzyme Linked Immunosorbent Assay (ELISA. Age-specific seropositivity rates were used to estimate seroconversion rates (SCR. Analysis indicated there had been at least a 60% decline in SCR in four out of five regions on the island. Changes in SCR showed a high degree of congruence with changes in parasite rate (PR and with regional reductions in all cause child mortality. The mean age adjusted concentration of anti-AMA-1 antibodies was mapped to identify areas where individual antibody responses were higher than expected. This approach confirmed the North West of the island as a major focus of continuing infection and an area where control interventions need to be concentrated or re-evaluated. CONCLUSION/INTERPRETATION: Both SCR and PR revealed heterogeneity in malaria transmission and demonstrated the variable effectiveness of malaria control measures. This work confirms the utility of serological analysis as an adjunct measure for monitoring transmission. Age-specific seroprevalence based evidence of changes in transmission over time will be of particular value when no baseline data are available. Importantly, SCR data provide additional

  12. Effect of electrical forepaw stimulation on capillary transit-time heterogeneity (CTH)

    DEFF Research Database (Denmark)

    Gutiérrez-Jiménez, Eugenio; Cai, Changsi; Mikkelsen, Irene Klærke;

    2016-01-01

    Functional hyperemia reduces oxygen extraction efficacy unless counteracted by a reduction of capillary transit-time heterogeneity of blood. We adapted a bolus tracking approach to capillary transit-time heterogeneity estimation for two-photon microscopy and then quantified changes in plasma mean...

  13. Assessing and reporting heterogeneity in treatment effects in clinical trials: a proposal

    Directory of Open Access Journals (Sweden)

    Kent David M

    2010-08-01

    Full Text Available Abstract Mounting evidence suggests that there is frequently considerable variation in the risk of the outcome of interest in clinical trial populations. These differences in risk will often cause clinically important heterogeneity in treatment effects (HTE across the trial population, such that the balance between treatment risks and benefits may differ substantially between large identifiable patient subgroups; the "average" benefit observed in the summary result may even be non-representative of the treatment effect for a typical patient in the trial. Conventional subgroup analyses, which examine whether specific patient characteristics modify the effects of treatment, are usually unable to detect even large variations in treatment benefit (and harm across risk groups because they do not account for the fact that patients have multiple characteristics simultaneously that affect the likelihood of treatment benefit. Based upon recent evidence on optimal statistical approaches to assessing HTE, we propose a framework that prioritizes the analysis and reporting of multivariate risk-based HTE and suggests that other subgroup analyses should be explicitly labeled either as primary subgroup analyses (well-motivated by prior evidence and intended to produce clinically actionable results or secondary (exploratory subgroup analyses (performed to inform future research. A standardized and transparent approach to HTE assessment and reporting could substantially improve clinical trial utility and interpretability.

  14. Heterogeneity in the Effect of Common Shocks on Healthcare Expenditure Growth.

    Science.gov (United States)

    Hauck, Katharina; Zhang, Xiaohui

    2016-09-01

    Healthcare expenditure growth is affected by important unobserved common shocks such as technological innovation, changes in sociological factors, shifts in preferences, and the epidemiology of diseases. While common factors impact in principle all countries, their effect is likely to differ across countries. To allow for unobserved heterogeneity in the effects of common shocks, we estimate a panel data model of healthcare expenditure growth in 34 OECD countries over the years 1980 to 2012, where the usual fixed or random effects are replaced by a multifactor error structure. We address model uncertainty with Bayesian model averaging, to identify a small set of robust expenditure drivers from 43 potential candidates. We establish 16 significant drivers of healthcare expenditure growth, including growth in GDP per capita and in insurance premiums, changes in financing arrangements and some institutional characteristics, expenditures on pharmaceuticals, population ageing, costs of health administration, and inpatient care. Our approach allows us to provide robust evidence to policy makers on the drivers that were most strongly associated with the growth in healthcare expenditures over the past 32 years. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26940606

  15. Necessity of using heterogeneous ellipsoidal Earth model with terrain to calculate co-seismic effect

    Science.gov (United States)

    Cheng, Huihong; Zhang, Bei; Zhang, Huai; Huang, Luyuan; Qu, Wulin; Shi, Yaolin

    2016-04-01

    Co-seismic deformation and stress changes, which reflect the elasticity of the earth, are very important in the earthquake dynamics, and also to other issues, such as the evaluation of the seismic risk, fracture process and triggering of earthquake. Lots of scholars have researched the dislocation theory and co-seismic deformation and obtained the half-space homogeneous model, half-space stratified model, spherical stratified model, and so on. Especially, models of Okada (1992) and Wang (2003, 2006) are widely applied in the research of calculating co-seismic and post-seismic effects. However, since both semi-infinite space model and layered model do not take the role of the earth curvature or heterogeneity or topography into consideration, there are large errors in calculating the co-seismic displacement of a great earthquake in its impacted area. Meanwhile, the computational methods of calculating the co-seismic strain and stress are different between spherical model and plane model. Here, we adopted the finite element method which could well deal with the complex characteristics (such as anisotropy, discontinuities) of rock and different conditions. We use the mash adaptive technique to automatically encrypt the mesh at the fault and adopt the equivalent volume force replace the dislocation source, which can avoid the difficulty in handling discontinuity surface with conventional (Zhang et al., 2015). We constructed an earth model that included earth's layered structure and curvature, the upper boundary was set as a free surface and the core-mantle boundary was set under buoyancy forces. Firstly, based on the precision requirement, we take a testing model - - a strike-slip fault (the length of fault is 500km and the width is 50km, and the slippage is 10m) for example. Because of the curvature of the Earth, some errors certainly occur in plane coordinates just as previous studies (Dong et al., 2014; Sun et al., 2012). However, we also found that: 1) the co

  16. Interatomic potential effects on dynamical heterogeneities in liquid SiO2

    Science.gov (United States)

    Hoang, V. V.

    2006-12-01

    Dynamical heterogeneities (DH) in low density liquid SiO2 have been investigated by molecular dynamics (MD) method. Simulations were done in the basic cube under periodic boundary conditions containing 3000 particles with the pair interatomic potentials, which have a weak electrostatic interaction and a Morse type short range interaction (PMSI). We have evaluated the non-Gaussian parameter for the self part of the van Hove correlation function and we found a clear evidence of the existence of DH in low density liquid SiO2. Moreover, the atomic displacement distribution (ADD) in a model has been obtained and it deviates from a Gaussian form. The results have been compared with those obtained in another liquid SiO2 system with the Born-Mayer interatomic potentials (BMP) in order to observe the interatomic potential effects on the DH in the system and indeed, the effects are strong. Calculations showed that particles of extremely low or fast mobility have a tendency to form a cluster and mean cluster size of most mobile and immobile particles in PMSI models increases with decreasing temperature. In contrast, no systematic changes have been obtained for the most mobile and immobile particles in BMP models. Calculations show that there is no relation between local particle environment and particle mobility in the system.

  17. The effects of laser welding on heterogeneous immunoassay performance in a microfluidic cartridge.

    Science.gov (United States)

    Mäntymaa, Anne; Halme, Jussi; Välimaa, Lasse; Kallio, Pasi

    2011-12-01

    Sealing of a microfluidic cartridge is a challenge, because the cartridge commonly contains heat-sensitive biomolecules that must also be protected from contamination. In addition, the objective is usually to obtain a sealing method suitable for mass production. Laser welding is a rapid technique that can be accomplished with low unit costs. Even though the technique has been widely adopted in industry, the literature on its use in microfluidic applications is not large. This paper is the first to report the effects of laser welding on the performance of the heterogeneous immunoassay in a polystyrene microfluidic cartridge in which biomolecules are immobilized into the reaction surface of the cartridge before sealing. The paper compares the immunoassay performance of microfluidic cartridges that are sealed either with an adhesive tape or by use of laser transmission welding. The model analyte used is thyroid stimulating hormone (TSH). The results show that the concentration curves in the laser-welded cartridges are very close to the curves in the taped cartridges. This indicates, first, that laser welding does not cause any significant reduction in immunoassay performance, and second, that the polystyrene cover does not have significant effect on the signal levels. Interestingly, the coefficients of variance between parallel samples were lower in the laser-welded cartridges than in the taped cartridges. PMID:22685505

  18. Effect of heterogenous and homogenous air gaps on dry heat loss through the garment.

    Science.gov (United States)

    Mert, Emel; Psikuta, Agnes; Bueno, Marie-Ange; Rossi, René M

    2015-11-01

    In real life conditions, the trapped air between the human body and the garment has uneven shape and vary over the body parts as a consequence of the complex geometry of the human body. However, the existing clothing models assume uniform air layer between the human body and the garment or its full contact, which may cause large error in the output of simulations. Therefore, the aim of this study was to investigate the effect of a heterogeneous vertical air gap with different configuration of folds (size and frequency) on dry heat loss using a heated cylinder (Torso). It was found that the presence of folds in the garment led to an increased heat loss from the body in comparison to a homogeneous air gap of comparable size. Interestingly, the size of folds did not have an influence on the dry heat loss. Additionally, the effect of the contact area on dry heat loss became important when exceeding a threshold of about 42%. The results from this study are useful for modelling of a realistic dry heat loss through the clothing and contribute to the improvement of design of protective and active sport garments. PMID:25796204

  19. Specification of electron beam quality from ionization distribution in central axis and a study about heterogenity effects in these distributions

    International Nuclear Information System (INIS)

    Some parameters on physical and terapeutic properties of the electron beams generated by ''nevratron XII'' accelerator of the Hospital of Medicine in Ribeirao Preto - USP, Brasil are evaluated. The effects from heterogenities into an irradiated mean, called ''phantom'' or simulator are studied. (M.J.C.)

  20. Similarity and heterogeneity effects in visual search are mediated by "segmentability".

    Science.gov (United States)

    Utochkin, Igor S; Yurevich, Maria A

    2016-07-01

    The heterogeneity of our visual environment typically reduces the speed with which a singleton target can be found. Visual search theories explain this phenomenon via nontarget similarities and dissimilarities that affect grouping, perceptual noise, and so forth. In this study, we show that increasing the heterogeneity of a display can facilitate rather than inhibit visual search for size and orientation singletons when heterogeneous features smoothly fill the transition between highly distinguishable nontargets. We suggest that this smooth transition reduces the "segmentability" of dissimilar items to otherwise separate subsets, causing the visual system to treat them as a near-homogenous set standing apart from a singleton. (PsycINFO Database Record PMID:26784002

  1. Representation of geological heterogeneities and their effects on mineral trapping during CO2 storage using numerical modeling

    International Nuclear Information System (INIS)

    The representation of geological heterogeneities and their impact on mineral trapping during CO2 storage was examined using TOUGHREACT. A series of simulations with increasing degrees of geological complexity were constructed and input parameters associated with different rock types were varied within reasonable ranges. Grid spacing was refined to determine the sensitivity of the models to grid size. Initial results indicate that the use of realistic relative permeability and capillary pressure input parameters for heterogeneous rock types have a significant effect on the extent of mineral sequestration due to the control relative permeability and capillary pressure have over the distribution of CO2 and pH. Significant numerical dispersion can occur when heterogeneities are represented by single grid layers. (authors)

  2. Representation of geological heterogeneities and their effects on mineral trapping during CO{sub 2} storage using numerical modeling

    Energy Technology Data Exchange (ETDEWEB)

    Hermanson, J.; Kirste, D. [Cooperative Research Centre for Greenhouse Gas Technologies - CO2CRC,GPO Box 463, Canberra, ACT, 2601 (Australia); Simon Fraser University, 8888 University Dr.,Burnaby, BC, V5A 1S6 (Canada)

    2013-07-01

    The representation of geological heterogeneities and their impact on mineral trapping during CO{sub 2} storage was examined using TOUGHREACT. A series of simulations with increasing degrees of geological complexity were constructed and input parameters associated with different rock types were varied within reasonable ranges. Grid spacing was refined to determine the sensitivity of the models to grid size. Initial results indicate that the use of realistic relative permeability and capillary pressure input parameters for heterogeneous rock types have a significant effect on the extent of mineral sequestration due to the control relative permeability and capillary pressure have over the distribution of CO{sub 2} and pH. Significant numerical dispersion can occur when heterogeneities are represented by single grid layers. (authors)

  3. Effects of city-size heterogeneity on epidemic spreading in a metapopulation: A reaction-diffusion approach

    CERN Document Server

    Lund, Halvor; Simonsen, Ingve

    2012-01-01

    We review and introduce a generalized reaction-diffusion approach to epidemic spreading in a metapopulation modeled as a complex network. The metapopulation consists of susceptible and infected individuals that are grouped in subpopulations symbolising cities and villages that are coupled by human travel in a transportation network. By analytic methods and numerical simulations we calculate the fraction of infected people in the metaopoluation in the long time limit, as well as the relevant parameters characterising the epidemic threshold that separates an epidemic from a non-epidemic phase. Within this model, we investigate the effect of a heterogeneous network topology and a heterogeneous subpopulation size distribution. Such a system is suited for epidemic modeling where small villages and big cities exist simultaneously in the metapopulation. We find that the heterogeneous conditions cause the epidemic threshold to be a non-trivial function of the reaction rates (local parameters), the network's topology ...

  4. The Effect of Point-spread Function Interaction with Radiance from Heterogeneous Scenes on Multitemporal Signature Analysis. [soybean stress

    Science.gov (United States)

    Duggin, M. J.; Schoch, L. B.

    1984-01-01

    The point-spread function is an important factor in determining the nature of feature types on the basis of multispectral recorded radiance, particularly from heterogeneous scenes and particularly from scenes which are imaged repetitively, in order to provide thematic characterization by means of multitemporal signature. To demonstrate the effect of the interaction of scene heterogeneity with the point spread function (PSF)1, a template was constructed from the line spread function (LSF) data for the thematic mapper photoflight model. The template was in 0.25 (nominal) pixel increments in the scan line direction across three scenes of different heterogeneity. The sensor output was calculated by considering the calculated scene radiance from each scene element occurring between the contours of the PSF template, plotted on a movable mylar sheet while it was located at a given position.

  5. Bony spinal canal changes that differentiate conjoined nerve roots from herniated nucleus pulposus

    International Nuclear Information System (INIS)

    CT examinations of the lumbar spine in 12 consecutive patients with conjoined nerve roots were reviewed. Asymmetry of the bony spinal canal, seen as slight dilatation of the ipsilateral lateral recess, was present in all cases. This finding, which is not typically associated with extruded free intervertebral disk fragments, should serve to distinguish these two entities

  6. Condylar bony changes in patients with temporomandibular disorders: a CBCT study

    International Nuclear Information System (INIS)

    Diagnosis of osteoarthritis most commonly depends on clinical and radiographic findings. The present study attempted to observe the bony changes in temporomandibular joint (TMJ) patients from all age groups. The first-visit clinical records and cone beam computed tomography (CBCT) data of 440 TMJs from 220 consecutive TMJ patients were reviewed retrospectively. The most frequent condylar bony change observed was sclerosis (133 joints, 30.2%) followed by surface erosion (129 joints, 29.3%), flattening of the articular surface (112 joints, 25.5%), and deviation in form (58 joints, 13.2%), which included 33 TMJs in a cane-shape, 16 with a lateral or medial pole depression, 6 with posterior condylar surface flattening, and 3 with a bifid-shaped condyle. Fifty-three joints (12.0%) showed hypoplastic condyles but only 1 joint showed hyperplasia. Osteophyte was found in 35 joints (8.0%) and subcortical cyst in 24 joints (5.5%), 5 of which had surface erosion as well. One hundred nineteen joints (27.0%) had only one kind of condylar bony change, 66 joints (15.0%) had two, 52 joints (11.8%) had three, 12 joints (5.0%) had four, and 6 joints (1.4%) had five kinds of condylar bony changes at the same time. Eighty-five (65.9%) of 129 joints with surface erosion had pain recorded at the chief complaint. With more widespread use of CBCT, more specific or detailed guidelines for osteoarthritis are needed.

  7. Condylar bony changes in patients with temporomandibular disorders: a CBCT study

    Energy Technology Data Exchange (ETDEWEB)

    Nah, Kyung Soo [Dept. of Oral and Maxillofacial Radiology, School of Dentistry, Pusan National University, Yangsan (Korea, Republic of)

    2012-09-15

    Diagnosis of osteoarthritis most commonly depends on clinical and radiographic findings. The present study attempted to observe the bony changes in temporomandibular joint (TMJ) patients from all age groups. The first-visit clinical records and cone beam computed tomography (CBCT) data of 440 TMJs from 220 consecutive TMJ patients were reviewed retrospectively. The most frequent condylar bony change observed was sclerosis (133 joints, 30.2%) followed by surface erosion (129 joints, 29.3%), flattening of the articular surface (112 joints, 25.5%), and deviation in form (58 joints, 13.2%), which included 33 TMJs in a cane-shape, 16 with a lateral or medial pole depression, 6 with posterior condylar surface flattening, and 3 with a bifid-shaped condyle. Fifty-three joints (12.0%) showed hypoplastic condyles but only 1 joint showed hyperplasia. Osteophyte was found in 35 joints (8.0%) and subcortical cyst in 24 joints (5.5%), 5 of which had surface erosion as well. One hundred nineteen joints (27.0%) had only one kind of condylar bony change, 66 joints (15.0%) had two, 52 joints (11.8%) had three, 12 joints (5.0%) had four, and 6 joints (1.4%) had five kinds of condylar bony changes at the same time. Eighty-five (65.9%) of 129 joints with surface erosion had pain recorded at the chief complaint. With more widespread use of CBCT, more specific or detailed guidelines for osteoarthritis are needed.

  8. On the biology of the bony otic capsule and the pathogenesis of otosclerosis

    DEFF Research Database (Denmark)

    Bloch, Sune Land

    2012-01-01

    In human otosclerosis, focal pathological bone remodeling occurs in significant amounts inside the normally anti-resorptive perilabyrinthine domain of the bony otic capsule. Otosclerosis causes hearing loss in 0.2-0.5% of the population by ankylosis of the footplate. The disease cannot be predict...... osteocyte survivors might distort the process and account for the otosclerotic morphology....

  9. Treatment effect heterogeneity for univariate subgroups in clinical trials: Shrinkage, standardization, or else.

    Science.gov (United States)

    Varadhan, Ravi; Wang, Sue-Jane

    2016-01-01

    Treatment effect heterogeneity is a well-recognized phenomenon in randomized controlled clinical trials. In this paper, we discuss subgroup analyses with prespecified subgroups of clinical or biological importance. We explore various alternatives to the naive (the traditional univariate) subgroup analyses to address the issues of multiplicity and confounding. Specifically, we consider a model-based Bayesian shrinkage (Bayes-DS) and a nonparametric, empirical Bayes shrinkage approach (Emp-Bayes) to temper the optimism of traditional univariate subgroup analyses; a standardization approach (standardization) that accounts for correlation between baseline covariates; and a model-based maximum likelihood estimation (MLE) approach. The Bayes-DS and Emp-Bayes methods model the variation in subgroup-specific treatment effect rather than testing the null hypothesis of no difference between subgroups. The standardization approach addresses the issue of confounding in subgroup analyses. The MLE approach is considered only for comparison in simulation studies as the "truth" since the data were generated from the same model. Using the characteristics of a hypothetical large outcome trial, we perform simulation studies and articulate the utilities and potential limitations of these estimators. Simulation results indicate that Bayes-DS and Emp-Bayes can protect against optimism present in the naïve approach. Due to its simplicity, the naïve approach should be the reference for reporting univariate subgroup-specific treatment effect estimates from exploratory subgroup analyses. Standardization, although it tends to have a larger variance, is suggested when it is important to address the confounding of univariate subgroup effects due to correlation between baseline covariates. The Bayes-DS approach is available as an R package (DSBayes). PMID:26485117

  10. Estudo experimental dos efeitos da heparina de baixo peso molecular (Enoxaparina na formação de calo ósseo em fêmures de ratos The effects of low-molecular-weight heparin (Enoxaparin on bony callus formation in rats' femurs - an experimental study

    Directory of Open Access Journals (Sweden)

    Salim Mussi Filho

    2006-01-01

    Full Text Available O tromboembolismo venoso é uma complicação grave que pode ocorrer após fraturas. O tratamento anticoagulante mais utilizado é com a heparina de baixo peso molecular (HBPM. Existem estudos que mostram que essa droga pode interferir no metabolismo ósseo. Com o objetivo de avaliar a influência da HBPM no processo de formação de calo ósseo, realizamos um estudo experimental em ratos. A amostra constituiu-se de 22 ratos de linhagem Wistar, machos, que foram submetidos à fratura diafisária de seus fêmures direitos. Foram divididos em dois grupos de 11. No grupo controle, os animais recebiam soro fisiológico e no grupo de estudo, recebiam HBPM, enoxaparina, diariamente, por 28 dias. Após este período os ratos foram submetidos à eutanásia e os fêmures foram avaliados. No estudo macroscópico foi constatada consolidação em 11 animais (100% que não receberam enoxaparina, e, em dez animais (90,9% que receberam a droga em estudo. No estudo histológico foi constatada a formação de calo ósseo em todos os fêmures. Concluiu-se neste experimento que a enoxaparina não altera o processo de consolidação óssea em fêmures de ratos Wistar.Venous thromboembolism is a serious complication that may follow fractures. The most commonly used anticoagulant treatment is low-molecular-weight heparin (LMWH. There are some studies showing that this drug may interfere on bone metabolism. With the objective of evaluating the LMWH influence on the process of bony callus formation, we conducted an experimental study on rats. Sample was constituted of 22 Wistar male rats, which were submitted to diaphyseal fracture on their right femurs. They were divided into two groups of 11 subjects each. In the control group, the animals received saline solution and in the study group, they received LMWH - enoxaparin - in a daily basis, during 28 days. After that period, the rats were submitted to euthanasia for femur assessment purposes. At the macroscopic study

  11. The Effect of Methyl, Hydroxyl, and Ketone Functional Groups on the Heterogeneous Oxidation of Succinic Acid Aerosol by OH Radicals

    Science.gov (United States)

    Chan, M.; Zhang, H.; Wilson, K. R.

    2013-12-01

    The heterogeneous oxidation of atmospheric organic aerosols can influence their effects on climate, human health, and visibility. During oxidation, functionalization occurs when an oxygenated functional group is added to a molecule, leaving the carbon skeleton intact. Fragmentation involves carbon-carbon bond cleavage and produces two products with smaller carbon numbers than the parent compound. To gain better insights into how the molecular structure of more oxygenated organic compounds affects heterogeneous reactivity, succinic acid aerosols are photo-oxidized in an aerosol flow tube reactor, and the reaction products are analyzed using Direct Analysis in Real Time Mass Spectrometry for online chemical analysis. The effect of various functional groups (CH3, OH, C=O) along the carbon backbone on the heterogeneous reaction mechanisms are also investigated using model compounds. For this series of compounds, the formation of more oxygenated products through functionalization can be explained by well-known condensation-phase reactions such as Russell and Bennett and Summers. The number of fragmentation products is found to increase with the presence of OH and CH3 groups. This can be attributed to the increased number of tertiary carbons, enhancing the fragmentation after multiple oxidation steps. Smaller dicaids (oxalic acid and malonic acid) can be formed through the fragmentation processes in the heterogeneous oxidation of succinic acid. The effect of molecular structure on reaction kinetics, volatilization, and the relative importance of functionalization and fragmentation pathways will be discussed.

  12. Effect of size and heterogeneity of samples on biomarker discovery: synthetic and real data assessment.

    OpenAIRE

    Barbara Di Camillo; Tiziana Sanavia; Matteo Martini; Giuseppe Jurman; Francesco Sambo; Annalisa Barla; Margherita Squillario; Cesare Furlanello; Gianna Toffolo; Claudio Cobelli

    2012-01-01

    MOTIVATION: The identification of robust lists of molecular biomarkers related to a disease is a fundamental step for early diagnosis and treatment. However, methodologies for the discovery of biomarkers using microarray data often provide results with limited overlap. These differences are imputable to 1) dataset size (few subjects with respect to the number of features); 2) heterogeneity of the disease; 3) heterogeneity of experimental protocols and computational pipelines employed in the a...

  13. The effect of native forest dynamics upon the arrangements of species in oak forests-analysis of heterogeneity effects at the example of epigeal arthropods

    OpenAIRE

    Langer, Marco

    2011-01-01

    The heterogeneity in species assemblages of epigeal spiders was studied in a natural forest and in a managed forest. Additionally the effects of small-scale microhabitat heterogeneity of managed and unmanaged forests were determined by analysing the spider assemblages of three different microhabitat structures (i. vegetation, ii. dead wood. iii. litter cover). The spider were collected in a block design by pitfall traps (n=72) in a 4-week interval. To reveal key environmental factors affectin...

  14. Heterogeneous nucleation promotes carrier transport in solution-processed organic field-effect transistors

    KAUST Repository

    Li, Ruipeng

    2012-09-04

    A new way to investigate and control the growth of solution-cast thin films is presented. The combination of in situ quartz crystal microbalance measurements with dissipation capabilities (QCM-D) and in situ grazing-incidence wide-angle X-ray scattering (GIWAXS) in an environmental chamber provides unique quantitative insights into the time-evolution of the concentration of the solution, the onset of nucleation, and the mode of growth of the organic semiconductor under varied drying conditions. It is demonstrated that careful control over the kinetics of solution drying enhances carrier transport significantly by promoting phase transformation predominantly via heterogeneous nucleation and sustained surface growth of a highly lamellar structure at the solid-liquid interface at the expense of homogeneous nucleation. A new way to investigate and control the growth of drop-cast thin films is presented. The solution-processing of small-molecule thin films of TIPS-pentacene is investigated using time-resolved techniques to reveal the mechanisms of nucleation and growth leading to solid film formation. By tuning the drying speed of the solution, the balance between surface and bulk growth modes is altered, thereby controlling the lamellar formation and tuning the carrier mobility in organic field-effect transistors Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Effect of the heterogeneity of metamaterials on the Casimir-Lifshitz interaction

    International Nuclear Information System (INIS)

    The Casimir-Lifshitz interaction between metamaterials is studied using a model that takes into account the structural heterogeneity of the dielectric and magnetic properties of the bodies. A recently developed perturbation theory for the Casimir-Lifshitz interaction between arbitrary material bodies is generalized to include nonuniform magnetic permeability profiles and used to study the interaction between the magneto-dielectric heterostructures within the leading order. The metamaterials are modeled as two-dimensional arrays of domains with varying permittivity and permeability. In the case of two semi-infinite bodies with flat boundaries, the patterned structure of the material properties is found to cause the normal Casimir-Lifshitz force to develop an oscillatory behavior when the distance between the two bodies is comparable to the wavelength of the patterned features in the metamaterials. The nonuniformity also leads to the emergence of lateral Casimir-Lifshitz forces, which tend to strengthen as the gap size becomes smaller. Our results suggest that the recent studies on Casimir-Lifshitz forces between metamaterials, which have been performed with the aim of examining the possibility of observing the repulsive force, should be revisited to include the effect of the patterned structure at the wavelength of several hundred nanometers that coincides with the relevant gap size in the experiments.

  16. The confounding effects of source isotopic heterogeneity on consumer-diet and tissue-tissue stable isotope relationships.

    Science.gov (United States)

    Codron, Daryl; Sponheimer, Matt; Codron, Jacqui; Newton, Ian; Lanham, John L; Clauss, Marcus

    2012-08-01

    Stable isotope analysis of consumer tissues document patterns of resource use because data are linearly related to isotope compositions of their source(s) (i.e., food, water, etc.). Deviations in parameters estimated for these relationships can arise from variations in consumer tissue-diet spacing (Δ(TS)) and the level of isotopic heterogeneity in the source(s). We present a set of simple hypotheses that distinguish between the effects of Δ(TS) and source isotope heterogeneity. The latter may arise via mixed diets, during tissue turnover, or by isotopic routing of dietary components. We apply these concepts to stable carbon and nitrogen isotope relationships between gut contents and body tissues of large mammal herbivores from mixed C(3)/C(4) South African savannas and test predictions based on the compound- and/or time-specific data archived within each material. Predicted effects of source isotope heterogeneity are readily detected in carbon isotope relationships between materials representing different time periods or comprising bulk versus protein-only diet components. Differences in Δ(TS) of carbon isotopes across mammal herbivore species with very different feeding niches (and diet isotope compositions) are likely to be small or non-existent in these habitats. Variations in Δ(TS) estimated for nitrogen isotopes are much greater, leading to inconsistencies that cannot be explained by diet or trophic level effects alone. The effects of source heterogeneity on isotopic relationships generate numerical artefacts that have been misinterpreted as variations in Δ(TS). We caution against generalized application of hypotheses based on assumptions of source isotopic homogeneity, even for single diets commonly used in laboratory studies. More careful consideration of how heterogeneity affects consumer-diet relationships is needed for many field and laboratory systems. PMID:22349754

  17. Endocrine and Local IGF-I in the Bony Fish Immune System

    Directory of Open Access Journals (Sweden)

    Anne-Constance Franz

    2016-01-01

    Full Text Available A role for GH and IGF-I in the modulation of the immune system has been under discussion for decades. Generally, GH is considered a stimulator of innate immune parameters in mammals and teleost fish. The stimulatory effects in humans as well as in bony fish often appear to be correlated with elevated endocrine IGF-I (liver-derived, which has also been shown to be suppressed during infection in some studies. Nevertheless, data are still fragmentary. Some studies point to an important role of GH and IGF-I particularly during immune organ development and constitution. Even less is known about the potential relevance of local (autocrine/paracrine IGF-I within adult and developing immune organs, and the distinct localization of IGF-I in immune cells and tissues of mammals and fish has not been systematically defined. Thus far, IGF-I has been localized in different mammalian immune cell types, particularly macrophages and granulocytes, and in supporting cells, but not in T-lymphocytes. In the present study, we detected IGF-I in phagocytic cells isolated from rainbow trout head kidney and, in contrast to some findings in mammals, in T-cells of a channel catfish cell line. Thus, although numerous analogies among mammals and teleosts exist not only for the GH/IGF-system, but also for the immune system, there are differences that should be further investigated. For instance, it is unclear whether the primarily reported role of GH/IGF-I in the innate immune response is due to the lack of studies focusing on the adaptive immune system, or whether it truly preferentially concerns innate immune parameters. Infectious challenges in combination with GH/IGF-I manipulations are another important topic that has not been sufficiently addressed to date, particularly with respect to developmental and environmental influences on fish growth and health.

  18. Reducing the effects of acoustic heterogeneity with an iterative reconstruction method from experimental data in microwave induced thermoacoustic tomography

    International Nuclear Information System (INIS)

    Purpose: An iterative reconstruction method has been previously reported by the authors of this paper. However, the iterative reconstruction method was demonstrated by solely using the numerical simulations. It is essential to apply the iterative reconstruction method to practice conditions. The objective of this work is to validate the capability of the iterative reconstruction method for reducing the effects of acoustic heterogeneity with the experimental data in microwave induced thermoacoustic tomography. Methods: Most existing reconstruction methods need to combine the ultrasonic measurement technology to quantitatively measure the velocity distribution of heterogeneity, which increases the system complexity. Different to existing reconstruction methods, the iterative reconstruction method combines time reversal mirror technique, fast marching method, and simultaneous algebraic reconstruction technique to iteratively estimate the velocity distribution of heterogeneous tissue by solely using the measured data. Then, the estimated velocity distribution is used subsequently to reconstruct the highly accurate image of microwave absorption distribution. Experiments that a target placed in an acoustic heterogeneous environment are performed to validate the iterative reconstruction method. Results: By using the estimated velocity distribution, the target in an acoustic heterogeneous environment can be reconstructed with better shape and higher image contrast than targets that are reconstructed with a homogeneous velocity distribution. Conclusions: The distortions caused by the acoustic heterogeneity can be efficiently corrected by utilizing the velocity distribution estimated by the iterative reconstruction method. The advantage of the iterative reconstruction method over the existing correction methods is that it is successful in improving the quality of the image of microwave absorption distribution without increasing the system complexity

  19. Reducing the effects of acoustic heterogeneity with an iterative reconstruction method from experimental data in microwave induced thermoacoustic tomography

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jinguo; Zhao, Zhiqin, E-mail: zqzhao@uestc.edu.cn; Song, Jian; Chen, Guoping; Nie, Zaiping [School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan 611731 (China); Liu, Qing-Huo [Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 (United States)

    2015-05-15

    Purpose: An iterative reconstruction method has been previously reported by the authors of this paper. However, the iterative reconstruction method was demonstrated by solely using the numerical simulations. It is essential to apply the iterative reconstruction method to practice conditions. The objective of this work is to validate the capability of the iterative reconstruction method for reducing the effects of acoustic heterogeneity with the experimental data in microwave induced thermoacoustic tomography. Methods: Most existing reconstruction methods need to combine the ultrasonic measurement technology to quantitatively measure the velocity distribution of heterogeneity, which increases the system complexity. Different to existing reconstruction methods, the iterative reconstruction method combines time reversal mirror technique, fast marching method, and simultaneous algebraic reconstruction technique to iteratively estimate the velocity distribution of heterogeneous tissue by solely using the measured data. Then, the estimated velocity distribution is used subsequently to reconstruct the highly accurate image of microwave absorption distribution. Experiments that a target placed in an acoustic heterogeneous environment are performed to validate the iterative reconstruction method. Results: By using the estimated velocity distribution, the target in an acoustic heterogeneous environment can be reconstructed with better shape and higher image contrast than targets that are reconstructed with a homogeneous velocity distribution. Conclusions: The distortions caused by the acoustic heterogeneity can be efficiently corrected by utilizing the velocity distribution estimated by the iterative reconstruction method. The advantage of the iterative reconstruction method over the existing correction methods is that it is successful in improving the quality of the image of microwave absorption distribution without increasing the system complexity.

  20. Effect of Subgrid Heterogeneity on Scaling Geochemical and Biogeochemical Reactions: A Case of U(VI) Desorption

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chongxuan; Shang, Jianying; Shan, Huimei; Zachara, John M.

    2014-02-04

    The effect of subgrid heterogeneity in sediment properties on the rate of uranyl[U(VI)] desorption was investigated using a sediment collected from the US Department of Energy Hanford site. The sediment was sieved into 7 grain size fractions that each exhibited different U(VI) desorption properties. Six columns were assembled using the sediment with its grain size fractions arranged in different spatial configurations to mimic subgrid heterogeneity in reactive transport properties. The apparent rate of U(VI) desorption varied significantly in the columns. Those columns with sediment structures leading to preferential transport had much lower rates of U(VI) desorption than those with relatively homogeneous transport. Modeling analysis indicated that the U(VI) desorption model and parameters characterized from well-mixed reactors significantly over-predicted the measured U(VI) desorption in the columns with preferential transport. A dual domain model, which operationally separates reactive transport properties into two subgrid domains improved the predictions significantly. A similar effect of subgrid heterogeneity, albeit at a less degree, was observed for denitrification, which also occurred in the columns. The results imply that subgrid heterogeneity is an important consideration in extrapolating reaction rates from the laboratory to field.

  1. The effect of reservoir heterogeneity on gas production from hydrate accumulations in the permafrost

    Energy Technology Data Exchange (ETDEWEB)

    Reagan, M. T.; Kowalsky, M B.; Moridis, G. J.; Silpngarmlert, S.

    2010-05-01

    The quantity of hydrocarbon gases trapped in natural hydrate accumulations is enormous, leading to significant interest in the evaluation of their potential as an energy source. Large volumes of gas can be readily produced at high rates for long times from methane hydrate accumulations in the permafrost by means of depressurization-induced dissociation combined with conventional technologies and horizontal or vertical well configurations. Initial studies on the possibility of natural gas production from permafrost hydrates assumed homogeneity in intrinsic reservoir properties and in the initial condition of the hydrate-bearing layers (either due to the coarseness of the model or due to simplifications in the definition of the system). These results showed great promise for gas recovery from Class 1, 2, and 3 systems in the permafrost. This work examines the consequences of inevitable heterogeneity in intrinsic properties, such as in the porosity of the hydrate-bearing formation, or heterogeneity in the initial state of hydrate saturation. Heterogeneous configurations are generated through multiple methods: (1) through defining heterogeneous layers via existing well-log data, (2) through randomized initialization of reservoir properties and initial conditions, and (3) through the use of geostatistical methods to create heterogeneous fields that extrapolate from the limited data available from cores and well-log data. These extrapolations use available information and established geophysical methods to capture a range of deposit properties and hydrate configurations. The results show that some forms of heterogeneity, such as horizontal stratification, can assist in production of hydrate-derived gas. However, more heterogeneous structures can lead to complex physical behavior within the deposit and near the wellbore that may obstruct the flow of fluids to the well, necessitating revised production strategies. The need for fine discretization is crucial in all cases to

  2. A randomization-based perspective of analysis of variance: a test statistic robust to treatment effect heterogeneity

    OpenAIRE

    Ding, Peng; Dasgupta, Tirthankar

    2016-01-01

    Fisher randomization tests for Neyman's null hypothesis of no average treatment effects are considered in a finite population setting associated with completely randomized experiments with more than two treatments. The consequences of using the F statistic to conduct such a test are examined both theoretically and computationally, and it is argued that under treatment effect heterogeneity, use of the F statistic can severely inflate the type I error of the Fisher randomization test. An altern...

  3. Wage effects of job-worker mismatches: Heterogeneous skills or institutional effects?

    OpenAIRE

    Allen J.P.; Velden R.K.W. van der; Badillo-Amador L.

    2013-01-01

    The strong wage effects related to mismatches between a workers education and that required in the job are usually attributed to assignment theory. This theory asserts that productivity and wages depend on the education-job match, which determines the utilization of skills. However, recent research shows that educational mismatches are only weakly related to skill utilization, which in any case fails to account for the bulk of the wage effects. Two alternative theories have been put forward t...

  4. Magnetic pyrite cinder as an efficient heterogeneous ozonation catalyst and synergetic effect of deposited Ce.

    Science.gov (United States)

    Wu, Deli; Liu, Ying; He, Hongping; Zhang, Yalei

    2016-07-01

    Heterogeneous catalytic ozonation was emerged to be a promising alternative in the mineralization of various persistent organic pollutants in recent decades. Magnetic pyrite cinder (PyC), which was employed as the catalyst in our investigation, was further deposited by Ce (Ce-PyC) to enhance its catalytic activity in the degradation of aqueous reactive black 5 (RB5). The results showed that additional 17.39%, 42.12% mineralization efficiency was obtained by O3/PyC, O3/Ce-PyC, respectively, in the degradation of RB5 compared to that of O3 alone under identical experimental condition. The reaction mechanism involved the enhanced mineralization of aqueous RB5 at the catalyst-solution interface via hydroxyl radicals produced by the reaction between O3 and catalyst surface. Besides surface hydroxyl, surface Ce(Ⅲ) was crucial for Ce-PyC in the enhanced generation of hydroxyl radicals. More surprisingly, it was found that both PyC and Ce-PyC could exert quite stable catalytic activity in a wide pH range from 3 to 10, which was supposed to be combined with inherently comprised various metal oxide, such as Fe2O3, Fe3O4, MnO2 and CuO. Ozone utilization evaluation demonstrated that PyC and Ce-PyC facilitated effective ozone decomposition, as ozone utilization efficiency (mgTOC/mgO3) of O3/PyC and O3/Ce-PyC increased 64.0%, 155.0%, respectively, compared to that of O3 alone. This investigation provided an effective alternative in the resource utilization of PyC, which was traditionally characterized as a waste material. PMID:27108370

  5. Effect of heterogeneity correction on dosimetric parameters of radiotherapy planning for thoracic esophageal cancer

    Energy Technology Data Exchange (ETDEWEB)

    Nakayama, Masao, E-mail: naka2008@med.kobe-u.ac.jp [Division of Radiation Oncology, Kobe University Graduate School of Medicine, Kobe, Hyogo (Japan); Yoshida, Kenji; Nishimura, Hideki; Miyawaki, Daisuke; Uehara, Kazuyuki; Okamoto, Yoshiaki [Division of Radiation Oncology, Kobe University Graduate School of Medicine, Kobe, Hyogo (Japan); Okayama, Takanobu [Radiology Department, Kobe University Hospital, Kobe, Hyogo (Japan); Sasaki, Ryohei [Division of Radiation Oncology, Kobe University Graduate School of Medicine, Kobe, Hyogo (Japan)

    2014-04-01

    The present study aimed to investigate the effect of heterogeneity correction (HC) on dosimetric parameters in 3-dimensional conformal radiotherapy planning for patients with thoracic esophageal cancer. We retrospectively analyzed 20 patients. Two treatment plans were generated for each patient using a superposition algorithm on the Xio radiotherapy planning system. The first plan was calculated without HC. The second was a new plan calculated with HC, using identical beam geometries and maintaining the same number of monitor units as the first. With regard to the planning target volume (PTV), the overall mean differences in the prescription dose, maximum dose, mean dose, and dose that covers 95% of the PTV between the first and second plans were 1.10 Gy (1.8%), 1.35 Gy (2.2%), 1.10 Gy (1.9%), and 0.56 Gy (1.0%), respectively. With regard to parameters related to the organs at risk (OARs), the mean differences in the absolute percentages of lung volume receiving greater than 5, 10, 20, and 30 Gy (lung V{sub 5}, V{sub 10}, V{sub 20}, and V{sub 30}) between the first and second plans were 7.1%, 2.7%, 0.4%, and 0.5%, respectively. These results suggest that HC might have a more pronounced effect on the percentages of lung volume receiving lower doses (e.g., V{sub 5} and V{sub 10}) than on the dosimetric parameters related to the PTV and other OARs.

  6. Transuranic Transmutation and Criticality Calculation Sensitivity to Heterogeneous Lattice Effects - 12391

    International Nuclear Information System (INIS)

    whereas U-238, Pu-242, and Pu-238 composition was not changed by taking into account the non-homogenous lattice effects. Heterogeneous lattice effects do change the calculated eigenvalue and transmutation rate in a non-uniform lattice of MOX fuel rods and UO2 fuel. However, the uncertainty in the ENDF data used by SCALE in these calculations is large enough that the infinite lattice assumption remains valid. (authors)

  7. Effect of Number of Days between Semen Sampling on Variance Heterogeneity of Semen Concentration of Young Simmental Bulls

    Directory of Open Access Journals (Sweden)

    Kristijan Grubišić

    2003-06-01

    In order to analyze heterogeneity of variance, four data sets with two days periods (i.e. two and three; three and four; four and five; and five and six days between semen samplings were derived. Similarly, three data sets with three days periods between semen samplings were derived. Variance and covariance components and associated heritabilities for such defined data sets were estimated by Restricted Maximum Likelihood from a set of single-trait animal models. Fixed effects were defined as birth year x season and number of days between collections, and animal effect was defined as a random effect. The heritability estimates ranged between 0.01 to 0.08. Days between collections influenced variance heterogeneity. An increase of days between collections increased additive and permanent environment variance, decreased error variance, thus the estimation of heritability was improved.

  8. Heterogeneous nanometer-scale Joule and Peltier effects in sub-25 nm thin phase change memory devices

    Science.gov (United States)

    Grosse, Kyle L.; Pop, Eric; King, William P.

    2014-09-01

    We measure heterogeneous power dissipation in phase change memory (PCM) films of 11 and 22 nm thin Ge2Sb2Te5 (GST) by scanning Joule expansion microscopy (SJEM), with sub-50 nm spatial and ˜0.2 K temperature resolution. The heterogeneous Joule and Peltier effects are explained using a finite element analysis (FEA) model with a mixture of hexagonal close-packed and face-centered cubic GST phases. Transfer length method measurements and effective media theory calculations yield the GST resistivity, GST-TiW contact resistivity, and crystal fraction of the GST films at different annealing temperatures. Further comparison of SJEM measurements and FEA modeling also predicts the thermopower of thin GST films. These measurements of nanometer-scale Joule, thermoelectric, and interface effects in PCM films could lead to energy-efficient designs of highly scaled PCM technology.

  9. From concepts, theory, and evidence of heterogeneity of treatment effects to methodological approaches: a primer

    Directory of Open Access Journals (Sweden)

    Willke Richard J

    2012-12-01

    Full Text Available Abstract Implicit in the growing interest in patient-centered outcomes research is a growing need for better evidence regarding how responses to a given intervention or treatment may vary across patients, referred to as heterogeneity of treatment effect (HTE. A variety of methods are available for exploring HTE, each associated with unique strengths and limitations. This paper reviews a selected set of methodological approaches to understanding HTE, focusing largely but not exclusively on their uses with randomized trial data. It is oriented for the “intermediate” outcomes researcher, who may already be familiar with some methods, but would value a systematic overview of both more and less familiar methods with attention to when and why they may be used. Drawing from the biomedical, statistical, epidemiological and econometrics literature, we describe the steps involved in choosing an HTE approach, focusing on whether the intent of the analysis is for exploratory, initial testing, or confirmatory testing purposes. We also map HTE methodological approaches to data considerations as well as the strengths and limitations of each approach. Methods reviewed include formal subgroup analysis, meta-analysis and meta-regression, various types of predictive risk modeling including classification and regression tree analysis, series of n-of-1 trials, latent growth and growth mixture models, quantile regression, and selected non-parametric methods. In addition to an overview of each HTE method, examples and references are provided for further reading. By guiding the selection of the methods and analysis, this review is meant to better enable outcomes researchers to understand and explore aspects of HTE in the context of patient-centered outcomes research.

  10. Heterogeneous Shock Effects in NWA 8159: a Unique new Martian Meteorite

    Science.gov (United States)

    Sharp, T. G.; Walton, E. L.; Hu, J.; Agee, C. B.

    2014-12-01

    NWA 8159 is a olivine-bearing, fine-grained augite basalt from Mars with SNC-like oxygen isotopes and Fe/Mn values. The sample consists of augite, plagioclase (An50-65), olivine (Fa61-76), magnetite and minor orthopyroxene. NWA 8159 has several mm-thick shock-melt veins that have crystallized to a fine-grained granular mixture of silicate and sulfide with a texture unlike that seen in other shocked meteorites. Raman spectra from the veins suggest a Ca-rich garnet in the veins. Although the shock effects in this sample are similar to those of other Martian meteorites, the plagioclase remains anisotropic (crystalline) with polysynthetic twinning and fractures throughout much of the sample. In the vicinity of shock veins, the plagioclase is isotropic and stoichiometric with undisturbed grain boundaries and no fractures. Some plagioclase in contact with shock melt has transformed to tissintite (Ca-jadelite like pyroxene). Fayalitic olivine is partially transformed to ahrensite (spinel) in contact with shock melt. As in several other shocked Martian meteorites, olivine is also transformed into a nanometer-scale mixture of oxide and silicate. Raman spectra from these areas are consistent with the presence of magnetite, rather than magnesiowüstite, as seen in other samples. Minor quartz grains have radiating fractures through the surrounding minerals indicative of partial back transformation from a high-density phase. Raman spectra from this material indicates stishovite and coesite. The coexistence of crystalline plagioclase and maskelynite suggests a moderate shock pressure of 16 - 23 GPa. However, the association of maskelynite and other transformation features with shock veins indicates the importance of high temperatures in creating heterogeneous shock features. Nanometer-scale mineralogy and transformation nano-structures will be investigated in FIB sections with analytical TEM to better constrain the mineralogy, transformation mechanisms and shock conditions.

  11. Effect of porosity heterogeneity on the permeability and tortuosity of gas diffusion layers in polymer electrolyte membrane fuel cells

    Science.gov (United States)

    Nabovati, Aydin; Hinebaugh, James; Bazylak, Aimy; Amon, Cristina H.

    2014-02-01

    In this paper, we study the effect of porosity heterogeneity on the bulk hydrodynamic properties (permeability and tortuosity) of simulated gas diffusion layers (GDLs). The porosity distributions of the heterogeneous reconstructed samples are similar to those previously reported in the literature for Toray TGP-H 120™ GDLs. We use the lattice Boltzmann method to perform pore-level flow simulations in the reconstructed GDL samples. Using the results of pore-level simulations, the effect of porosity distribution is characterized on the predicted in- and cross-plane permeability and tortuosity. It was found that porosity heterogeneity causes a higher in-plane permeability and lower in-plane tortuosity, while the effect is opposite in the cross-plane direction, that is a lower cross-plane permeability and a higher cross-plane tortuosity. We further investigate the effect of adding poly-tetra-fluoro-ethylene (PTFE) & binder material to the reconstructed GDL samples. Three fiber volume percentages of 50, 75, and 100% are considered. Overall, increasing the fiber volume percentage reduces the predicted in- and cross-plane permeability and tortuosity values. A previously reported relationship for permeability of fibrous materials is fitted to the predicted permeability values, and the magnitude of the fitting parameter is reported as a function of fiber volume percentage.

  12. Prostate position relative to pelvic bony anatomy based on intraprostatic gold markers and electronic portal imaging

    International Nuclear Information System (INIS)

    Purpose: To describe the relative positions and motions of the prostate, pelvic bony anatomy, and intraprostatic gold fiducial markers during daily electronic portal localization of the prostate. Methods and Materials: Twenty prostate cancer patients were treated supine with definitive external radiotherapy according to an on-line target localization protocol using three or four intraprostatic gold fiducial markers and an electronic portal imaging device. Daily pretherapy and through-treatment electronic portal images (EPIs) were obtained for each of four treatment fields. The patients' pelvic bony anatomy, intraprostatic gold markers, and a best visual match to the target (i.e., prostate) were identified on simulation digitally reconstructed radiographs and during daily treatment setup and delivery. These data provided quantitative inter- and intrafractional analysis of prostate motion, its position relative to the bony anatomy, and the individual intraprostatic fiducial markers. Treatment planning margins, with and without on-line localization, were subsequently compared. Results: A total of 22,266 data points were obtained from daily pretherapy and through-treatment EPIs. The pretherapy three-dimensional (3D) average displacement of the fiducial markers, as a surrogate for the prostate, was 5.6 mm, which improved to 2.8 mm after use of the localization protocol. The bony anatomy 3D average displacement was 4.4 mm both before and after localization to the prostate (p = 0.46). Along the superior-inferior (SI), anterior-posterior (AP), and right-left (RL) axes, the average prostate displacement improved from 2.5, 3.7, and 1.9 mm, respectively, before localization to 1.4, 1.6, and 1.1 mm after (all p < 0.001). The pretherapy to through-treatment position of the bony landmarks worsened from 1.7 to 2.5 mm (p < 0.001) in the SI axis, remained statistically unchanged at 2.8 mm (p = 0.39) in the AP axis, and improved from 2.0 to 1.2 mm in the RL axis (p < 0.001). There

  13. Medial depression with bony dehiscence of lamina papyracea as an anatomic variation: CT evaluation

    International Nuclear Information System (INIS)

    To evaluate the incidence and CT findings of the medial depression and bony dehiscence of lamina papyracea as an anatomic variation. 1472 PNS CTs of the patients with symptoms of chronic sinusitis were retrospectively evaluated. The total incidence of depressed lamina papyracea as an anatomic variation was 3.5%(52/1472) on PNS CT. There was a statistically significant correlation between the increasing age and the incidence of depressed lamina papyracea. Depression of lamina papyracea anterior to the basal lamella were more common than those of the posterior depression. Associated findings were herniation of adjacent fatty tissue in all cases and the medial bowing and hypertrophied configuration of the medial rectus muscle without significant herniation in 19 cases(34%). Nontraumatic, asymptomatic depression with bony dehiscence of lamina papyracea as an anatomic variation is not uncommon with the incidence of 3.5%. Recognition of its existence and degree may be helpful in avoiding various ocular complication during ethmoid surgery

  14. Effects of induced magnetic field and homogeneous–heterogeneous reactions on stagnation flow of a Casson fluid

    Directory of Open Access Journals (Sweden)

    C.S.K. Raju

    2016-06-01

    Full Text Available In this study, we analyzed the induced magnetic field effect on the stagnation-point flow of a non-Newtonian fluid over a stretching sheet with homogeneous–heterogeneous reactions and non-uniform heat source or sink. The transformed ordinary differential equations are solved numerically using Runge–Kutta and Newton's method. For physical relevance we analyzed the behavior of homogeneous and heterogeneous profiles individually in the presence of induced magnetic field. The effects of different non-dimensional governing parameters on velocity, induced magnetic field, temperature and concentration profiles, along with the skin friction coefficient and local Nusselt number, are discussed and presented through graphs. The results of the present study are validated by comparing with the existed literature. Results indicate that induced magnetic field parameter and stretching ratio parameter have the tendency to enhance the heat transfer rate.

  15. Homogenized moment tensor and the effect of near-field heterogeneities on nonisotropic radiation in nuclear explosion

    Science.gov (United States)

    Burgos, Gaël.; Capdeville, Yann; Guillot, Laurent

    2016-06-01

    We investigate the effect of small-scale heterogeneities close to a seismic explosive source, at intermediate periods (20-50 s), with an emphasis on the resulting nonisotropic far-field radiation. First, using a direct numerical approach, we show that small-scale elastic heterogeneities located in the near-field of an explosive source, generate unexpected phases (i.e., long period S waves). We then demonstrate that the nonperiodic homogenization theory applied to 2-D and 3-D elastic models, with various pattern of small-scale heterogeneities near the source, leads to accurate waveforms at a reduced computational cost compared to direct modeling. Further, it gives an interpretation of how nearby small-scale features interact with the source at low frequencies, through an explicit correction to the seismic moment tensor. In 2-D simulations, we find a deviatoric contribution to the moment tensor, as high as 21% for near-source heterogeneities showing a 25% contrast of elastic values (relative to a homogeneous background medium). In 3-D this nonisotropic contribution reaches 27%. Second, we analyze intermediate-periods regional seismic waveforms associated with some underground nuclear explosions conducted at the Nevada National Security Site and invert for the full moment tensor, in order to quantify the relative contribution of the isotropic and deviatoric components of the tensor. The average value of the deviatoric part is about 35%. We conclude that the interactions between an explosive source and small-scale local heterogeneities of moderate amplitude may lead to a deviatoric contribution to the seismic moment, close to what is observed using regional data from nuclear test explosions.

  16. Effects of root mat buoyancy and heterogeneity on floating fen hydrology

    NARCIS (Netherlands)

    Stofberg, S.F.; Engelen, van Joeri; Witte, J.Ph.M.; Zee, van der S.E.A.T.M.

    2016-01-01

    Floating fen ecosystems are home to several protected habitats and species. Their development and conservation require special
    attention regarding water management. Although they are known to be heterogeneous and partially buoyant, their root mats are
    simulated in hydrological models as homo

  17. Effects of farm heterogeneity and methods for upscaling on modelled nitrogen losses in agricultural landscapes

    DEFF Research Database (Denmark)

    Dalgaard, Tommy; Hutchings, Nicholas John; Dragosits, U;

    2011-01-01

    The aim of this study is to illustrate the importance of farm scale heterogeneity on nitrogen (N) losses in agricultural landscapes. Results are exemplified with a chain of N models calculating farm-N balances and distributing the N-surplus to N-losses (volatilisation, denitrification, leaching) ...

  18. Comparative physiological selectivity of Pennsylvanian to Jurassic extinction in bony fish, sharks and invertebrates

    OpenAIRE

    Vazquez, Priscilla Rose

    2015-01-01

    The end-Permian and end-Triassic extinctions coincided with flood basalt eruptions that would have released large quantities of CO2 into the atmosphere, leading to ocean warming, anoxia, and perhaps acidification. Multiple stresses present during these extinction events provide analogues for anthropogenic CO2 emissions and can help us understand which taxonomic groups will be threatened by ocean acidification and warming. Bony fish and sharks (Actinoptyergii and Chondrichthyes) have cellular ...

  19. Stereotactic Bony Trajectory Preservation for Responsive Neurostimulator Lead Placement Following Depth EEG Recording.

    Science.gov (United States)

    Miller, Kai; Halpern, Casey H

    2016-01-01

    Responsive neurostimulation (RNS) is rapidly gaining traction as a therapy for medically refractory epilepsy. Depth electrode placement for stimulation of a deep seizure focus may be indicated after the focus has been electrophysiologically localized using depth electroencephalography (depth EEG). We describe a simple technique whereby the bony trajectories created during initial stereotactic placement of depth EEG electrodes are preserved and reused for RNS with depth electrodes. This technique may help to improve targeting and maximize surgical efficiency. PMID:27158578

  20. Knee joint secondary motion accuracy improved by quaternion-based optimizer with bony landmark constraints.

    Science.gov (United States)

    Wang, Hongsheng; Zheng, Naiqaun Nigel

    2010-12-01

    Skin marker-based motion analysis has been widely used in biomechanical studies and clinical applications. Unfortunately, the accuracy of knee joint secondary motions is largely limited by the nonrigidity nature of human body segments. Numerous studies have investigated the characteristics of soft tissue movement. Utilizing these characteristics, we may improve the accuracy of knee joint motion measurement. An optimizer was developed by incorporating the soft tissue movement patterns at special bony landmarks into constraint functions. Bony landmark constraints were assigned to the skin markers at femur epicondyles, tibial plateau edges, and tibial tuberosity in a motion analysis algorithm by limiting their allowed position space relative to the underlying bone. The rotation matrix was represented by quaternion, and the constrained optimization problem was solved by Fletcher's version of the Levenberg-Marquardt optimization technique. The algorithm was validated by using motion data from both skin-based markers and bone-mounted markers attached to fresh cadavers. By comparing the results with the ground truth bone motion generated from the bone-mounted markers, the new algorithm had a significantly higher accuracy (root-mean-square (RMS) error: 0.7 ± 0.1 deg in axial rotation and 0.4 ± 0.1 deg in varus-valgus) in estimating the knee joint secondary rotations than algorithms without bony landmark constraints (RMS error: 1.7 ± 0.4 deg in axial rotation and 0.7 ± 0.1 deg in varus-valgus). Also, it predicts a more accurate medial-lateral translation (RMS error: 0.4 ± 0.1 mm) than the conventional techniques (RMS error: 1.2 ± 0.2 mm). The new algorithm, using bony landmark constrains, estimates more accurate secondary rotations and medial-lateral translation of the underlying bone. PMID:21142329

  1. Treatment of painful bony metastasis of prostatic cancer by Samarium 153 (Quadramet)

    International Nuclear Information System (INIS)

    Full text: SUMMARY. Introduction: Despite of the progress realized in the treatment of prostatic cancer, the appearance of bony metastasis had limited considerably the life expectancy. In that case, pain is the most important symptom to consider because of its most frequency and the most difficult to manage. Its management needs a multidisciplinary approach with the objective of improving patients' life quality. Aim: The objective of the study was to evaluate the interest of metabolic radiotherapy to 153Samarium-EDTMP, for the pain treatment of bony metastasis of prostatic cancer. Material and method: This was a multicentric study where data were collected retrospectively lasting 40 months. The study was conducted in three departments of nuclear medicine: Institute Salah Azaiez, the center 'CERU', and military hospital of Tunis. Forty five patients with painful bony metastasis of prostatic cancer had been enrolled in the study. Efficacy and factors influencing treatment response had been assessed as well as toxicity and the cause of failures. Results: Positive response was obtained in 92.1% of cases and response was completed in 36.5% of cases. Results obtained after multiple administrations of treatment, showed that the cures could be repeated and could have results comparable to the first cure. The efficacy of our treatment is at least equivalent to the one obtained by the other methods of treatment, with very rare adverse events. The only toxicity was a hematological disorder that is usually moderated and reversible as well with complete recovery in around 8 weeks. Conclusion: Our results supported the efficacy of 'Samarium 153-EDTMP' in the management of painful bony metastasis of prostatic cancer. (author)

  2. Effect of Pore-Scale Heterogeneity and Capillary-Viscous Fingering on Commingled Waterflood Oil Recovery in Stratified Porous Media

    OpenAIRE

    Al-Shalabi, Emad W.; Ghosh, B

    2016-01-01

    Oil recovery prediction and field pilot implements require basic understanding and estimation of displacement efficiency. Corefloods and glass micromodels are two of the commonly used experimental methods to achieve this. In this paper, waterflood recovery is investigated using layered etched glass micromodel and Berea sandstone core plugs with large permeability contrasts. This study focuses mainly on the effect of permeability (heterogeneity) in stratified porous media with no cross-flow. T...

  3. In situ FTIR Investigation of Magnetic Field Effect on Heterogeneous Photocatalytic Degradation of Benzene over Pt/TiO2

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    In situ FTIR spectroscopy was utlized to investigate the magnetic field effect on the heterogeneous photocatalytic degradation of benzene over platinized titania (Pt/TiO2). The results revealed that the employment of magnetic field may not change the mechanism of photocatalytic degradation of benzene, however, it greatly facilitate the conversion of benzene to phenol and quinone, as well as the transformation from phenol to quinone, resulting in opening the benzene ring easily and promoting the production of CO2.

  4. Pore Fluid Effects on Shear Modulus in a Model of Heterogeneous Rocks, Reservoirs, and Granular Media

    Energy Technology Data Exchange (ETDEWEB)

    Berryman, J G

    2005-03-23

    To provide quantitative measures of the importance of fluid effects on shear waves in heterogeneous reservoirs, a model material called a ''random polycrystal of porous laminates'' is introduced. This model poroelastic material has constituent grains that are layered (or laminated), and each layer is an isotropic, microhomogeneous porous medium. All grains are composed of exactly the same porous constituents, and have the same relative volume fractions. The order of lamination is not important because the up-scaling method used to determine the transversely isotropic (hexagonal) properties of the grains is Backus averaging, which--for quasi-static or long-wavelength behavior--depends only on the volume fractions and layer properties. Grains are then jumbled together totally at random, filling all space, and producing an overall isotropic poroelastic medium. The poroelastic behavior of this medium is then analyzed using the Peselnick-Meister-Watt bounds (of Hashin-Shtrikman type). We study the dependence of the shear modulus on pore fluid properties and determine the range of behavior to be expected. In particular we compare and contrast these results to those anticipated from Gassmann's fluid substitution formulas, and to the predictions of Mavko and Jizba for very low porosity rocks with flat cracks. This approach also permits the study of arbitrary numbers of constituents, but for simplicity the numerical examples are restricted here to just two constituents. This restriction also permits the use of some special exact results available for computing the overall effective stress coefficient in any two-component porous medium. The bounds making use of polycrystalline microstructure are very tight. Results for the shear modulus demonstrate that the ratio of compliance differences R (i.e., shear compliance changes over bulk compliance changes when going from drained to undrained behavior, or vice versa) is usually nonzero and can take a wide

  5. The effect of land cover heterogeneity of MODIS pixel on canopy LAI estimation

    Science.gov (United States)

    Manninen, T.; Puttonen, N.

    2012-04-01

    The boreal zone land cover has a very significant influence on the northern hemisphere albedo and is an important component of the northern hemisphere carbon budget. Both albedo and the leaf area index (LAI) are one of the most important biophysical vegetation parameters and belong to the Essential Climate Variables (ECV) . In addition, in winter time the boreal forest albedo is a complicated combination of snow and canopy radiative properties, so that the albedo is a function of the canopy LAI. One possibility to estimate LAI using optical satellite data is by determination of spectral vegetation indices (SVIs), such as the reduced simple ratio (RSR). It uses the visible near infrared and short wave infrared channels. In large areas moderate resolution instruments, like MODIS, are suitable for LAI mapping. Yet, the heterogeneity of land cover in many boreal areas, for example in Finland, causes a challenge for LAI estimation. This effect was studied using several Landsat and MODIS images and the high resolution CORINE land cover map covering the same area in various parts of Finland. The atmospheric correction of the Landsat images was adjusted so that each MODIS pixel reflectance matched the average of the Landsat pixel reflectances within the MODIS pixel. The LAI values for Landsat and MODIS images were then determined using the RSR index. The LAI average of forested Landsat pixels was compared to the corresponding MODIS pixel LAI as a function of open water area fraction in the MODIS pixel. A regression function was determined to derive a method to correct the MODIS based LAI values with the open water area fraction. It turned out that the existence of open water in the MODIS pixels reduces the determined canopy LAI value on the average 30%. Also other land cover classes affect the LAI value, but the effect of water is largest, because the reflectance of water deviates so much from that of the canopy. The canopy LAI map of whole Finland was then calculated

  6. The Effect of Surface Heterogeneity on the Structure Parameters of Temperature and Specific Humidity: A Large-Eddy Simulation Case Study for the LITFASS-2003 Experiment

    NARCIS (Netherlands)

    Maronga, B.; Hartogensis, O.K.; Raasch, S.; Beyrich, F.

    2014-01-01

    We conduct a high-resolution large-eddy simulation (LES) case study in order to investigate the effects of surface heterogeneity on the (local) structure parameters of potential temperature C2T and specific humidity C2q in the convective boundary layer (CBL). The kilometre-scale heterogeneous land-u

  7. The Effects of Realistic Geological Heterogeneity on Seismic Modeling: Applications in Shear Wave Generation and Near-Surface Tunnel Detection

    Science.gov (United States)

    Sherman, Christopher Scott

    Naturally occurring geologic heterogeneity is an important, but often overlooked, aspect of seismic wave propagation. This dissertation presents a strategy for modeling the effects of heterogeneity using a combination of geostatistics and Finite Difference simulation. In the first chapter, I discuss my motivations for studying geologic heterogeneity and seis- mic wave propagation. Models based upon fractal statistics are powerful tools in geophysics for modeling heterogeneity. The important features of these fractal models are illustrated using borehole log data from an oil well and geomorphological observations from a site in Death Valley, California. A large part of the computational work presented in this disserta- tion was completed using the Finite Difference Code E3D. I discuss the Python-based user interface for E3D and the computational strategies for working with heterogeneous models developed over the course of this research. The second chapter explores a phenomenon observed for wave propagation in heteroge- neous media - the generation of unexpected shear wave phases in the near-source region. In spite of their popularity amongst seismic researchers, approximate methods for modeling wave propagation in these media, such as the Born and Rytov methods or Radiative Trans- fer Theory, are incapable of explaining these shear waves. This is primarily due to these method's assumptions regarding the coupling of near-source terms with the heterogeneities and mode conversion. To determine the source of these shear waves, I generate a suite of 3D synthetic heterogeneous fractal geologic models and use E3D to simulate the wave propaga- tion for a vertical point force on the surface of the models. I also present a methodology for calculating the effective source radiation patterns from the models. The numerical results show that, due to a combination of mode conversion and coupling with near-source hetero- geneity, shear wave energy on the order of 10% of the

  8. Correlation between target volume and electron transport effects affecting heterogeneity corrections in stereotactic body radiotherapy for lung cancer

    International Nuclear Information System (INIS)

    Recently, stereotactic body radiotherapy (SBRT) for lung cancer is conducted with heterogeneity-corrected treatment plans, as the correction greatly affects the dose delivery to the lung tumor. In this study, the correlation between the planning target volume (PTV) and the dose delivery is investigated by separation of the heterogeneity correction effects into photon attenuation and electron transport. Under Institutional Review Board exemption status, 74 patients with lung cancer who were treated with SBRT were retrospectively evaluated. All treatment plans were generated using an anisotropic analytical algorithm (AAA) of an Eclipse (Varian Medical Systems, Palo Alto, CA) treatment planning system. Two additional plans were created using the same treatment parameters (monitor units, beam angles and energy): a plan with no heterogeneity correction (NC), and a plan calculated with a pencil beam convolution algorithm (PBC). Compared with NC, AAA and PBC isocenter doses were on average 13.4% and 21.8% higher, respectively. The differences in the isocenter dose and the dose coverage for 95% of the PTV (D95%) between PBC and AAA were correlated logarithmically (ρ = 0.78 and ρ = 0.46, respectively) with PTV. Although D95% calculated with AAA was in general 2.9% larger than that for NC, patients with a small PTV showed a negative ΔD95% for AAA due to the significant effect of electron transport. The PTV volume shows logarithmic correlation with the effects of the lateral electron transport. These findings indicate that the dosimetric metrics and prescription, especially in clinical trials, should be clearly evaluated in the context of target volume characteristics and with proper heterogeneity correction. (author)

  9. Spatial and temporal trends of drought effects in a heterogeneous semi-arid forest ecosystem

    Science.gov (United States)

    Assal, Timothy J.; Anderson, Patrick J.; Sibold, Jason

    2016-01-01

    Drought has long been recognized as a driving mechanism in the forests of western North America and drought-induced mortality has been documented across genera in recent years. Given the frequency of these events are expected to increase in the future, understanding patterns of mortality and plant response to severe drought is important to resource managers. Drought can affect the functional, physiological, structural, and demographic properties of forest ecosystems. Remote sensing studies have documented changes in forest properties due to direct and indirect effects of drought; however, few studies have addressed this at local scales needed to characterize highly heterogeneous ecosystems in the forest-shrubland ecotone. We analyzed a 22-year Landsat time series (1985–2012) to determine changes in forest in an area that experienced a relatively dry decade punctuated by two years of extreme drought. We assessed the relationship between several vegetation indices and field measured characteristics (e.g. plant area index and canopy gap fraction) and applied these indices to trend analysis to uncover the location, direction and timing of change. Finally, we assessed the interaction of climate and topography by forest functional type. The Normalized Difference Moisture Index (NDMI), a measure of canopy water content, had the strongest correlation with short-term field measures of plant area index (R2 = 0.64) and canopy gap fraction (R2 = 0.65). Over the entire time period, 25% of the forested area experienced a significant (p-value trend in NDMI, compared to less than 10% in a positive trend. Coniferous forests were more likely to be associated with a negative NDMI trend than deciduous forest. Forests on southern aspects were least likely to exhibit a negative trend while north aspects were most prevalent. Field plots with a negative trend had a lower live density, and higher amounts of standing dead and down trees compared to plots with no trend. Our analysis

  10. Exploring dynamical complexity in diffusion driven predator-prey systems: Effect of toxin producing phytoplankton and spatial heterogeneities

    International Nuclear Information System (INIS)

    In this paper, dynamical complexities in two reaction-diffusion (RD) model systems are explored. A spatial heterogeneity in the form of linear spatial gradient in the reproductive growth rate of the phytoplankton is incorporated in both the model systems. Extra mortality of the zooplankton due to toxin production by the phytoplankton is included in the second reaction diffusion model system. Effect of toxin production and spatial heterogeneity in the model systems are studied. Toxin production does not seem to have an appreciable effect on the asymptotic dynamics of the model systems. On the other hand, spatial heterogeneity does influence the dynamics. In particular, it increases the frequency of occurrence of chaos as evident from two dimensional parameter scans. Both these model systems display short term recurrent chaos [Rai V. Chaos in natural populations: edge or wedge? Ecol Complex 2004;1: 127-38] as they reside on 'edges of chaos' (EOC) [Rai V, Upadhyay RK. Evolving to the edge of chaos: chance or necessity? Chaos, Solitons and Fractals 2006;30:1074-87]. This suggests that the ecological systems have a tendency to evolve to EOC. The study corroborates the inferences drawn from an earlier study by Rai and Upadhyay [Rai V, Upadhyay RK. Evolving to the edge of chaos: chance or necessity? Chaos, Solitons and Fractals 2006;30:1074-87]. The system's dynamics is largely unpredictable and admits bursts of short-term predictability.

  11. Effect of kinematic stability of initial orientation on deformation heterogeneity and ductile failure in duplex stainless steel during uniaxial tension

    International Nuclear Information System (INIS)

    The crystal plasticity finite element method (CPFEM) was used to investigate the effect of the kinematic stability of the initial orientations on the deformation heterogeneity and ductile failure of ferrite and austenite phases in duplex stainless steel (DSS) during uniaxial tension. The individual stress–strain relationships of ferrite and austenite phases in DSS were evaluated via in situ neutron diffraction in combination with the CPFEM. A CPFEM based on the volume elements (VEs) of a unit cell of DSS with a regular banded microstructure demonstrated that the kinematic stability of the initial orientations significantly affected the deformation heterogeneity and ductile failure in the constituent phases in VEs during uniaxial tension. The regions susceptible to ductile failure were identified as being in the austenite phase near the phase boundaries of ferrite and austenite

  12. Heterogeneity in a solid solution and its effect on the magnetization: hemo-ilmenite as an example

    Science.gov (United States)

    Eva, S.; Luster, J.; Fischer, H.; Gehring, A. U.

    2006-12-01

    Mineral phases of the hematite-ilmenite solid solutions series (y FeTiO3 - (1-y) α{Fe2O3; 0 AFM ordered areas in the boundary layers which became more prominent with decreasing temperature. The simultaneous occurrence of SP clusters and AFM ordered areas generated spin-glass like properties. At T AFM ordered areas set in and was documented by an increase in Hc. At lower temperature, the additional shift of the hysteresis indicated a change in AFM anisotropy. At 5 K, the hemo-ilmenite can be described as a heterogeneous system with local variations in AFM anisotropies which are most likely caused by structural defects or size distribution of magnetic nanostructures. This study provides evidence that exchange coupling caused by nano-scale heterogeneity can significantly influence the magnetic properties of hemo-ilmenite particles. The effect of exchange coupling on the magnetization of larger bodies (e.g. intrusions) remains an open question.

  13. Heterogeneous Catalysis

    OpenAIRE

    Schlögl, R.

    2015-01-01

    A heterogeneous catalyst is a functional material that continually creates active sites with its reactants under reaction conditions. These sites change the rates of chemical reactions of the reactants localized on them without changing the thermodynamic equilibrium between the materials.

  14. Heterogeneous Catalysis.

    Science.gov (United States)

    Miranda, R.

    1989-01-01

    Described is a heterogeneous catalysis course which has elements of materials processing embedded in the classical format of catalytic mechanisms and surface chemistry. A course outline and list of examples of recent review papers written by students are provided. (MVL)

  15. ''TIBERE'' a calculational method of the effect of lattice heterogeneity on the neutron leakage

    International Nuclear Information System (INIS)

    The flux calculation in a heterogeneous assembly in APOLLO and APOLLO-2 codes is based on the collision probability method. On the contrary, the neutron leakage calculation is accomplished for a flux-weighted homogenized assembly, which is a good approximation in the case of a non-voided assembly (PWR in normal conditions). If an assembly contains voided zones (for example as the consequence of LOCA) or if the reactor, in normal operation, contains void or transparent media (Na), the approximation may become much more debatable. The formalism proposed here treats the leakage taking into account the heterogeneity of the medium, the leakage being treated as a type of reaction analogous to others. This formalism is introduced in APOLLO-2 code as a module and uses only tools similar to those used for the calculation of the flux. (author)

  16. Effects of homogeneous-heterogeneous reactions in flow of Powell-Eyring fluid

    Institute of Scientific and Technical Information of China (English)

    T Hayat; M Imtiaz; A Alsaedi

    2015-01-01

    The steady two-dimensional flow of Powell-Eyring fluid is investigated. The flow is caused by a stretching surface with homogeneous-heterogeneous reactions. The governing nonlinear differential equations are reduced to the ordinary differential equations by similarity transformations. The analytic solutions are presented in series forms by homotopy analysis method (HAM). Convergence of the obtained series solutions is explicitly discussed. The physical significance of different parameters on the velocity and concentration profiles is discussed through graphical illustrations. It is noticed that the boundary layer thickness increases by increasing the Powell-Eyring fluid material parameter (ε) whereas it decreases by increasing the fluid material parameter (δ). Further, the concentration profile increases when Powell-Eyring fluid material parameters increase. The concentration is also an increasing function of Schmidt number and decreasing function of strength of homogeneous reaction. Also mass transfer rate increases for larger rate of heterogeneous reaction.

  17. Scale-dependent effects of a heterogeneous landscape on genetic differentiation in the Central American squirrel monkey (Saimiri oerstedii.

    Directory of Open Access Journals (Sweden)

    Mary E Blair

    Full Text Available Landscape genetic studies offer a fine-scale understanding of how habitat heterogeneity influences population genetic structure. We examined population genetic structure and conducted a landscape genetic analysis for the endangered Central American Squirrel Monkey (Saimiri oerstedii that lives in the fragmented, human-modified habitats of the Central Pacific region of Costa Rica. We analyzed non-invasively collected fecal samples from 244 individuals from 14 groups for 16 microsatellite markers. We found two geographically separate genetic clusters in the Central Pacific region with evidence of recent gene flow among them. We also found significant differentiation among groups of S. o. citrinellus using pairwise F(ST comparisons. These groups are in fragments of secondary forest separated by unsuitable "matrix" habitats such as cattle pasture, commercial African oil palm plantations, and human residential areas. We used an individual-based landscape genetic approach to measure spatial patterns of genetic variance while taking into account landscape heterogeneity. We found that large, commercial oil palm plantations represent moderate barriers to gene flow between populations, but cattle pastures, rivers, and residential areas do not. However, the influence of oil palm plantations on genetic variance was diminished when we restricted analyses to within population pairs, suggesting that their effect is scale-dependent and manifests during longer dispersal events among populations. We show that when landscape genetic methods are applied rigorously and at the right scale, they are sensitive enough to track population processes even in species with long, overlapping generations such as primates. Thus landscape genetic approaches are extremely valuable for the conservation management of a diverse array of endangered species in heterogeneous, human-modified habitats. Our results also stress the importance of explicitly considering the heterogeneity of

  18. Impact of Heterogeneity in Sexual Behavior on Effectiveness in Reducing HIV Transmission with Test-and-Treat Strategy.

    Science.gov (United States)

    Rozhnova, Ganna; van der Loeff, Maarten F Schim; Heijne, Janneke C M; Kretzschmar, Mirjam E

    2016-08-01

    The WHO's early-release guideline for antiretroviral treatment (ART) of HIV infection based on a recent trial conducted in 34 countries recommends starting treatment immediately upon an HIV diagnosis. Therefore, the test-and-treat strategy may become more widely used in an effort to scale up HIV treatment and curb further transmission. Here we examine behavioural determinants of HIV transmission and how heterogeneity in sexual behaviour influences the outcomes of this strategy. Using a deterministic model, we perform a systematic investigation into the effects of various mixing patterns in a population of men who have sex with men (MSM), stratified by partner change rates, on the elimination threshold and endemic HIV prevalence. We find that both the level of overdispersion in the distribution of the number of sexual partners and mixing between population subgroups have a large influence on endemic prevalence before introduction of ART and on possible long term effectiveness of ART. Increasing heterogeneity in risk behavior may lead to lower endemic prevalence levels, but requires higher coverage levels of ART for elimination. Elimination is only feasible for populations with a rather low degree of assortativeness of mixing and requires treatment coverage of almost 80% if rates of testing and treatment uptake by all population subgroups are equal. In this case, for fully assortative mixing and 80% coverage endemic prevalence is reduced by 57%. In the presence of heterogeneity in ART uptake, elimination is easier to achieve when the subpopulation with highest risk behavior is tested and treated more often than the rest of the population, and vice versa when it is less. The developed framework can be used to extract information on behavioral heterogeneity from existing data which is otherwise hard to determine from population surveys. PMID:27479074

  19. The effect of organic ion-exchange resin on properties of heterogeneous ion-exchange membranes

    Czech Academy of Sciences Publication Activity Database

    Křivčík, J.; Vladařová, J.; Hadrava, J.; Černín, A.; Brožová, Libuše

    2010-01-01

    Roč. 14, - (2010), s. 179-184. ISSN 1944-3994. [Membrane Science and Technology Conference of Visegrad Countries /4./ PERMEA 2009, 07.07.2009-11.07.2009] R&D Projects: GA MPO FT-TA4/116 Institutional research plan: CEZ:AV0Z40500505 Keywords : heterogeneous ion-exchange membrane * membrane modification * particle size of distribution Subject RIV: CG - Electrochemistry Impact factor: 0.752, year: 2010

  20. Heterogeneous TiO2 Photocatalysis : Fundamental Chemical Aspects and Effects of Solid Phase Alterations

    OpenAIRE

    Diesen, Veronica

    2013-01-01

    Heterogeneous photocatalysis on TiO2 is an emerging green technology for water disinfection. The rationale for this technology is based on in-situ generation of highly reactive transitory species for degradation of organic and inorganic pollutants as well as microorganisms. Recent research has concentrated on improving the efficiency of the photocatalytic process, however, some fundamental information on the mechanistic aspects and rate limiting properties still remain elusive.     The focus ...

  1. Spatial and temporal heterogeneity in a subtropical reservoir and their effects over the benthic macroinvertebrate community

    Directory of Open Access Journals (Sweden)

    Frederico Guilherme de Souza Beghelli

    2014-09-01

    Full Text Available AIM: The objective of the present study was to demonstrate the influences of the environment spatial heterogeneity on benthic macroinvertebrates considering transverse and longitudinal gradients as also seasonality. METHODS: Four samplings were performed: two in the wet and two in the dry season in the riverine, transitional and lacustrine zones in the littoral and profundal regions of Itupararanga reservoir, SP, Brazil. Abiotic characterization of the water and of the sediment was performed. The biotic characterization was based on richness, dominance, diversity, and density of organisms, as well as on the relative abundance of predominant taxa. Two-way ANOSIM analyses were performed for both biotic and abiotic components, in order to test the significance of the differences in the longitudinal and transverse directions as well as of the differences between seasons. RESULTS: Compartmentalization was present in both directions, longitudinal and transverse. In a general way, the littoral region presented higher diversity values when compared with the profundal region, and the riverine zone presented high densities and high percentage of taxons, which usually indicate organic pollution. The differentiation between the transitional and lacustrine zones was determined mainly by taxonomic composition. Seasonality was also observed and the transportation of small particles, the entrance of nutrients, and the presence of macrophytes were considered as determinants for differentiation. CONCLUSIONS: Together, these results demonstrate the responses of benthic macroinvertebrate communities considering distinct sources of variation: longitudinal heterogeneity, determined by the increasing distance from the forming rivers that leads to a gradient of physical and chemical conditions; transverse heterogeneity, determined by the proximity with the land environment and depth differences. Seasonal heterogeneity was recorded during the period of this research and

  2. Monte Carlo Investigation on the Effect of Heterogeneities on Strut Adjusted Volume Implant (SAVI) Dosimetry

    Science.gov (United States)

    Koontz, Craig

    Breast cancer is the most prevalent cancer for women with more than 225,000 new cases diagnosed in the United States in 2012 (ACS, 2012). With the high prevalence, comes an increased emphasis on researching new techniques to treat this disease. Accelerated partial breast irradiation (APBI) has been used as an alternative to whole breast irradiation (WBI) in order to treat occult disease after lumpectomy. Similar recurrence rates have been found using ABPI after lumpectomy as with mastectomy alone, but with the added benefit of improved cosmetic and psychological results. Intracavitary brachytherapy devices have been used to deliver the APBI prescription. However, inability to produce asymmetric dose distributions in order to avoid overdosing skin and chest wall has been an issue with these devices. Multi-lumen devices were introduced to overcome this problem. Of these, the Strut-Adjusted Volume Implant (SAVI) has demonstrated the greatest ability to produce an asymmetric dose distribution, which would have greater ability to avoid skin and chest wall dose, and thus allow more women to receive this type of treatment. However, SAVI treatments come with inherent heterogeneities including variable backscatter due to the proximity to the tissue-air and tissue-lung interfaces and variable contents within the cavity created by the SAVI. The dose calculation protocol based on TG-43 does not account for heterogeneities and thus will not produce accurate dosimetry; however Acuros, a model-based dose calculation algorithm manufactured by Varian Medical Systems, claims to accurately account for heterogeneities. Monte Carlo simulation can calculate the dosimetry with high accuracy. In this thesis, a model of the SAVI will be created for Monte Carlo, specifically using MCNP code, in order to explore the affects of heterogeneities on the dose distribution. This data will be compared to TG-43 and Acuros calculated dosimetry to explore their accuracy.

  3. Effects of Spatial Heterogeneity in Rainfall and Vegetation Type on Soil Moisture and Evapotranspiration

    OpenAIRE

    Puma, Michael J.; Celia, Michael A.; Rodriguez-Iturbe, Ignacio; Nordbotten, Jan M.; Guswa, Andrew J.; Kavetski, Dmitri

    2016-01-01

    Nonlinear plant-scale interactions controlling the soil-water balance are generally not valid at larger spatial scales due to spatial heterogeneity in rainfall and vegetation type. The relationships between spatially averaged variables are hysteretic even when unique relationships are imposed at the plant scale. The characteristics of these hysteretic relationships depend on the size of the averaging area and the spatial properties of the soil, vegetation, and rainfall. We upscale the plant-s...

  4. Heterogeneous Effects of Medical Interventions on the Health of Low-Risk Newborns

    OpenAIRE

    Daysal, N. Meltem; Trandafir, Mircea; van Ewijk, Reyn

    2016-01-01

    We investigate the impact of early-life medical interventions on low-risk newborn health. A policy rule in The Netherlands creates large discontinuities in medical treatments at gestational week 37. Using a regression discontinuity design, we find no health benefits from additional treatments for average newborns. However, there is substantial heterogeneity in returns to treatments with significant health benefits for newborns in the lowest income quartile and no benefits in higher income qua...

  5. Modeling the Heterogeneous Effects of GHG Mitigation Policies on Global Agriculture and Forestry

    Science.gov (United States)

    Golub, A.; Henderson, B.; Hertel, T. W.; Rose, S. K.; Sohngen, B.

    2010-12-01

    Agriculture and forestry are envisioned as potentially key sectors for climate change mitigation policy, yet the depth of analysis of mitigation options and their economic consequences remains remarkably shallow in comparison to that for industrial mitigation. Farming and land use change - much of it induced by agriculture -account for one-third of global greenhouse gas (GHG) emissions. Any serious attempt to curtail these emissions will involve changes in the way farming is conducted, as well as placing limits on agricultural expansion into areas currently under more carbon-intensive land cover. However, agriculture and forestry are extremely heterogeneous, both in the technology and intensity of production, as well as in the GHG emissions intensity of these activities. And these differences, in turn, give rise to significant changes in the distribution of agricultural production, trade and consumption in the wake of mitigation policies. This paper assesses such distributional impacts via a global economic analysis undertaken with a modified version of the GTAP model. The paper builds on a global general equilibrium GTAP-AEZ-GHG model (Golub et al., 2009). This is a unified modeling framework that links the agricultural, forestry, food processing and other sectors through land, and other factor markets and international trade, and incorporates different land-types, land uses and related CO2 and non-CO2 GHG emissions and sequestration. The economic data underlying this work is the global GTAP data base aggregated up to 19 regions and 29 sectors. The model incorporates mitigation cost curves for different regions and sectors based on information from the US-EPA. The forestry component of the model is calibrated to the results of the state of the art partial equilibrium global forestry model of Sohngen and Mendelson (2007). Forest carbon sequestration at both the extensive and intensive margins are modeled separately to better isolate land competition between

  6. Molecular interface effect of heterogeneous molecular junctions consisting of nonfluorinated and fluorinated phthalocyanines.

    Science.gov (United States)

    Liu, Yuhong; Yang, Deliang; Wang, Chen

    2006-10-26

    We report the tunneling behavior of homogeneous and heterogeneous molecular junctions using p-type molecules of iron phthalocyanine (FePc), phthalocyanine (H(2)Pc), and copper(II) octaalkoxyl substituted phthalocyanine (CuPcOC8) and n-type molecule of copper hexadecafluorophthalocyanine (F(16)CuPc). The molecular films formed on the electrode surfaces were inspected by X-ray photoelectron spectroscopy (XPS). The measured characteristic tunneling curves of single-component phthalocyanines revealed comparable energy gaps for homogeneous tunneling junctions using the photoemission method. In contrast, for the heterogeneous tunnel junctions of mixed phthalocyanines including fluorinated phthalocyanine a distinctive offset of the energy gaps to the positive bias voltage direction can be clearly identified. It is suggested that the substitution of phthalocyanines and surface affinity of phthalocyanines could contribute to the controlled phase separation within the heterogeneous tunneling junctions. The apparent shift of the tunneling spectra is attributed to the existence of an internal electric field originated with the phase separation of the binary mixture of p-type and n-type phthalocyanines within the tunneling junction. PMID:17048888

  7. Effective reaction rates for transport of particles to heterogeneous reactive (or porous) surfaces under shear

    Science.gov (United States)

    Shah, Preyas; Shaqfeh, Eric S. G.

    2015-11-01

    Mass transfer to heterogeneous reactive (or porous) surfaces is common in applications like heterogeneous catalysis, and biological porous media transport like drug delivery. This is modeled as advection-diffusion in a shear flow to an inert surface with first order reactive patches. We study transport of point particles using boundary element simulations. We show that the heterogeneous surface can be replaced with a uniform-flux boundary condition related to the Sherwood number (S), aka, the dimensionless flux to the reactive region. In the dilute limit of reactive regions, large-scale interaction between the reactive patches is important. In the dilute limit of inert regions, [S] grows as the reciprocal of the inert area fraction. Based on the method of resistances and numerical results, we provide correlations for [S] for general reactive surfaces and flow conditions. We model finite sized particles as general spheroids, specifically for biological applications. We do Brownian Dynamics simulations to account for hydrodynamic and steric interactions with the flow field and the domain geometry, and compare to the point particle results. We observe that anisotropic particles gave a higher pore transport flux compared to spherical particles at all flow conditions.

  8. The dual effect of ephaptic coupling on cardiac conduction with heterogeneous expression of connexin 43.

    Science.gov (United States)

    Wei, Ning; Mori, Yoichiro; Tolkacheva, Elena G

    2016-05-21

    Decreased and heterogeneous expression of connexin 43 (Cx43) are common features in animal heart failure models. Ephpatic coupling, which relies on the presence of junctional cleft space between the ends of adjacent cells, has been suggested to play a more active role in mediating intercellular electrical communication when gap junctions are reduced. To better understand the interplay of Cx43 expression and ephaptic coupling on cardiac conduction during heart failure, we performed numerical simulations on our model when Cx43 expression is reduced and heterogeneous. Under severely reduced Cx43 expression, we identified three new phenomena in the presence of ephaptic coupling: alternating conduction, in which ephaptic and gap junction-mediated mechanisms alternate; instability of planar fronts; and small amplitude action potential (SAP), which has a smaller potential amplitude than the normal action potential. In the presence of heterogeneous Cx43 expression, ephaptic coupling can either prevent or promote conduction block (CB) depending on the Cx43 knockout (Cx43KO) content. When Cx43KO content is relatively high, ephaptic coupling reduces the probabilities of CB. However, ephaptic coupling promotes CB when Cx43KO and wild type cells are mixed in roughly equal proportion, which can be attributed to an increase in current-to-load mismatch. PMID:26968493

  9. Effect of Heterogeneity of Vertex Activation on Epidemic Spreading in Temporal Networks

    Directory of Open Access Journals (Sweden)

    Yixin Zhu

    2014-01-01

    Full Text Available Development of sensor technologies and the prevalence of electronic communication services provide us with a huge amount of data on human communication behavior, including face-to-face conversations, e-mail exchanges, phone calls, message exchanges, and other types of interactions in various online forums. These indirect or direct interactions form potential bridges of the virus spread. For a long time, the study of virus spread is based on the aggregate static network. However, the interaction patterns containing diverse temporal properties may affect dynamic processes as much as the network topology does. Some empirical studies show that the activation time and duration of vertices and links are highly heterogeneous, which means intense activity may be followed by longer intervals of inactivity. We take heterogeneous distribution of the node interactivation time as the research background to build an asynchronous communication model. The two sides of the communication do not have to be active at the same time. One derives the threshold of virus spreading on the communication mode and analyzes the reason the heterogeneous distribution of the vertex interactivation time suppresses the spread of virus. At last, the analysis and results from the model are verified on the BA network.

  10. The Effects of Heterogeneities on Seismic Wave Propagation in the Climax Stock

    Science.gov (United States)

    Webb, C. H.; Snelson, C. M.; White, R. L.; Emmitt, R. F.; Barker, D. L.; Abbott, R. E.; Bonal, N. D.

    2011-12-01

    The Comprehensive Nuclear Test-Ban Treaty requires the ability to detect low-yield (less than 150kton) nuclear events. This kind of monitoring can only be done seismically on a regional scale (within 2000km). At this level, it is difficult to distinguish between low-yield nuclear events and non-nuclear events of similar magnitude. In order to confidently identify a nuclear event, a more detailed understanding of nuclear seismic sources is needed. In particular, it is important to know the effects of local geology on the seismic signal. This study focuses on P-wave velocity in heterogeneous granitoid. The Source Physics Experiment (SPE) is currently performing low-yield tests with chemical explosives at the Nevada National Security Site (NNSS). The exact test site was chosen to be in the Climax Stock, a cretaceous granodiorite and quartz-monzonite pluton located in Area 15 of the NNSS. It has been used in the past for the Hard Hat and Pile Driver nuclear tests, which provided legacy data that can be used to simulate wave propagation. The Climax Stock was originally chosen as the site of the SPE partly because of its assumed homogeneity. It has since been discovered that the area of the stock where the SPE tests are being performed contains a perched water table. In addition, the stock is known to contain an extensive network of faults, joints, and fractures, but the exact effect of these structural features on seismic wave velocity is not fully understood. The SPE tests are designed to seismically capture the explosion phenomena from the near- to the far-field transition of the seismic waveform. In the first SPE experiment, 100kg of chemical explosives were set off at a depth of 55m. The blast was recorded with an array of sensors and diagnostics, including accelerometers, geophones, rotational sensors, short-period and broadband seismic sensors, Continuous Reflectometry for Radius vs. Time Experiment, Time of Arrival, Velocity of Detonation, and infrasound sensors

  11. The Effects of Heterogeneities on Seismic Wave Propagation in the Climax Stock

    Energy Technology Data Exchange (ETDEWEB)

    Hagan Webb, C., Snelson, C. M., White, R., Emmitt, R., Barker, D., Abbott, R., Bonal, N.

    2011-12-01

    The Comprehensive Nuclear Test-Ban Treaty requires the ability to detect low-yield (less than 150kton) nuclear events. This kind of monitoring can only be done seismically on a regional scale (within 2000km). At this level, it is difficult to distinguish between low-yield nuclear events and non-nuclear events of similar magnitude. In order to confidently identify a nuclear event, a more detailed understanding of nuclear seismic sources is needed. In particular, it is important to know the effects of local geology on the seismic signal. This study focuses on P-wave velocity in heterogeneous granitoid. The Source Physics Experiment (SPE) is currently performing low-yield tests with chemical explosives at the Nevada National Security Site (NNSS). The exact test site was chosen to be in the Climax Stock, a cretaceous granodiorite and quartz-monzonite pluton located in Area 15 of the NNSS. It has been used in the past for the Hard Hat and Pile Driver nuclear tests, which provided legacy data that can be used to simulate wave propagation. The Climax Stock was originally chosen as the site of the SPE partly because of its assumed homogeneity. It has since been discovered that the area of the stock where the SPE tests are being performed contains a perched water table. In addition, the stock is known to contain an extensive network of faults, joints, and fractures, but the exact effect of these structural features on seismic wave velocity is not fully understood. The SPE tests are designed to seismically capture the explosion phenomena from the near- to the far-field transition of the seismic waveform. In the first SPE experiment, 100kg of chemical explosives were set off at a depth of 55m. The blast was recorded with an array of sensors and diagnostics, including accelerometers, geophones, rotational sensors, short-period and broadband seismic sensors, Continuous Reflectometry for Radius vs. Time Experiment, Time of Arrival, Velocity of Detonation, and infrasound sensors

  12. Unsharp masking technique as a preprocessing filter for improvement of 3D-CT image of bony structure in the maxillofacial region

    International Nuclear Information System (INIS)

    We evaluated the usefulness of the unsharp masking technique as a preprocessing filter to improve 3D-CT images of bony structure in the maxillofacial region. The effect of the unsharp masking technique with several combinations of mask size and weighting factor on image resolution was investigated using a spatial frequency phantom made of bone-equivalent material. The 3D-CT images were obtained with scans perpendicular to and parallel to the phantom plates. The contrast transfer function (CTF) and the full width at half maximum (FWHM) of each spatial frequency component were measured. The FWHM was expressed as a ratio against the actual thickness of phantom plate. The effect on pseudoforamina was assessed using sliced CT images obtained in clinical bony 3D-CT examinations. The effect of the unsharp masking technique on image quality was also visually evaluated using five clinical fracture cases. CTFs did not change. FWHM ratios of original 3D-CT images were smaller than 1.0, regardless of the scanning direction. Those in scans perpendicular to the phantom plates were not changed by the unsharp masking technique. Those in parallel scanning were increased by mask size and weighting factor. The area of pseudoforamina decreased with increases in mask size and weighting factor. The combination of mask size 3 x 3 pixels and weighting factor 5 was optimal. Visual evaluation indicated that preprocessing with the unsharp masking technique improved the image quality of the 3D-CT images. The unsharp masking technique is useful as a preprocessing filter to improve the 3D-CT image of bony structure in the maxillofacial region. (author)

  13. Modeling the large-scale effects of surface moisture heterogeneity on wetland carbon fluxes in the West Siberian Lowland

    Directory of Open Access Journals (Sweden)

    T. J. Bohn

    2013-10-01

    Full Text Available We used a process-based model to examine the role of spatial heterogeneity of surface and sub-surface water on the carbon budget of the wetlands of the West Siberian Lowland over the period 1948–2010. We found that, while surface heterogeneity (fractional saturated area had little overall effect on estimates of the region's carbon fluxes, sub-surface heterogeneity (spatial variations in water table depth played an important role in both the overall magnitude and spatial distribution of estimates of the region's carbon fluxes. In particular, to reproduce the spatial pattern of CH4 emissions recorded by intensive in situ observations across the domain, in which very little CH4 is emitted north of 60° N, it was necessary to (a account for CH4 emissions from unsaturated wetlands and (b use spatially varying methane model parameters that reduced estimated CH4 emissions in the northern (permafrost half of the domain (and/or account for lower CH4 emissions under inundated conditions. Our results suggest that previous estimates of the response of these wetlands to thawing permafrost may have overestimated future increases in methane emissions in the permafrost zone.

  14. Effects of imidapril on heterogeneity of action potential and calcium current of ventriclar myocytes in infarcted rabbits

    Institute of Scientific and Technical Information of China (English)

    YangLI; QiaoXUE; JieMA; Cun-taiZHANG; PingQIU; LinWANG; WeiGAO; ReiCHENG; Zai-yinLU; Shi-wenWANG

    2004-01-01

    AIM: To investigate the effects of chronic treatment with imidapril on the electrophysiologic heterogeneous change of the noninfarcted myocardium of rabbits after myocardial infarction and the mechanism of its antiarrhythmic efficacy. METHODS: Rabbits with left coronary artery ligation were prepared and allowed to recover for 8 weeks. Myocytes were isolated from subendocardial, midmyocardial, and subepicardial regions of the noninfarcted left ventricular wall. Action potentials and calcium current were recorded using whole-cell patch clamp technique. RESULTS: The action potential duration of repolarization 90 % (APD90) was more prolonged in midmyocardium rather than in subepicardium and subendocardium with healed myocardial infarction. The transmural dispersion of repolarization (TDR) was increased in the three ventricular regions. The amplitude of/Ca-L was enhanced but its density was decreased in noninfarcted ventricular myocytes due to increased cell membrane capacitance. The increased differences of calcium currents among subepicardium, midmyocardium, and subendocardium were also discovered. Normalization of heterogeneous changes in repolarization after treatment with imidapril was observed and decrease of TDR in noninfarcted area was measured. Early after depolarization (EAD) events of noninfarcted midmyocardium were markedly decreased by imidapril. CONCLUSION: Imidapril reduced the electrophysiologic heterogeneities in noninfarcted area in rabbits after myocardial infarction. This ability of imidapril may contribute to its antiarrhythmic efficacy.

  15. Effects of imidapril on heterogeneity of action potential and calcium current of ventriclar myocytes in infarcted rabbits

    Institute of Scientific and Technical Information of China (English)

    Yang LI; Shi-wen WANG; Qiao XUE; Jie MA; Cun-tai ZHANG; Ping QIU; Lin WANG; Wei GAO; Rei CHENG; Zai-ying LU

    2004-01-01

    AIM: To investigate the effects of chronic treatment with imidapril on the electrophysiologic heterogeneous change of the noninfarcted myocardium of rabbits after myocardial infarction and the mechanism of its antiarrhythmic efficacy. METHODS: Rabbits with left coronary artery ligation were prepared and allowed to recover for 8 weeks.Myocytes were isolated from subendocardial, midmyocardial, and subepicardial regions of the noninfarcted left ventricular wall. Action potentials and calcium current were recorded using whole-cell patch clamp technique.RESULTS: The action potential duration of repolarization 90 % (APD90)was more prolonged in midmyocardium rather than in subepicardium and subendocardium with healed myocardial infarction. The transmural dispersion of repolarization (TDR) was increased in the three ventricular regions. The amplitude of ICa-L was enhanced but its density was decreased in noninfarcted ventricular myocytes due to increased cell membrane capacitance. The increased differences of calcium currents among subepicardium, midmyocardium, and subendocardium were also discovered. Normalization of heterogeneous changes in repolarization after treatment with imidapril was observed and decrease of TDR in noninfarcted area was measvred. Early after depolarization (EAD) events of noninfarcted midmyocardium were markedly decreased by imidapril. CONCLUSION: Imidapril reduced the electrophysiologic heterogeneities in noninfarcted area in rabbits after myocardial infarction. This ability of imidapril may contribute to its antiarrhythmic efficacy.

  16. Heterogeneous of potassium currents in free wall myocytes from the infarcted rabbit ventricle and regression effects of imidapril

    Institute of Scientific and Technical Information of China (English)

    Yang Li; Shiwen Wang; Yi Wen; Bin Xu; Yuqi Liu; Zongbin Li; Xinhua Wang

    2008-01-01

    Objective To define the heterogeneous changes of ion channels in the noninfarcted myocardium after myocardial infarction in rabbit and effects of imidapril.Mehods Rabbits with left coronary artery ligation were prepared and allowed to recover for 8 wk.Myocytes were isolated from subendocardial,midmyocardial and subepicardial regions of the noninfarcted left ventricular free wall.Ion currents were recorded with whole-cell patch clamp way.Results The densities of the transient outward K+ currents (I to) and the inward rectifier K+ currents (I K1) were greatly reduced in midmyocardium and subepicardium while two currents reduced gently in subendocardium.The densities of the delayed rectifier K+ currents (I K) were reduced in noninfarcted three layers similarly.Imidapril could reverse the changes of membrane currents in healed myocardial infarction cells and depress the dispersion of repolarization.Conclusions The heterogeneities of K currents are enhanced in noninfarcted area.Normalization of heterogeneous changes of repolarization after treatment with imidapril was observed.

  17. Computed tomographic features of the bony canal of the cochlear nerve in pediatric patients with unilateral sensorineural hearing loss

    International Nuclear Information System (INIS)

    The aim of this study was to evaluate the diameters of the various bony canals of the inner ear in patients with sensorineural hearing loss (SNHL) and establish criteria for detecting hypoplasia of the bony canal of the cochlear nerve. Measurements obtained in 118 patients without inner ear malformations among 160 patients with unilateral SNHL were analyzed. The diameters of the internal auditory canal and the bony canals of the cochlear, vestibular, and facial nerves were measured on transverse or coronal computed tomographic images. Mean values (±standard deviation (SD)) were compared between the affected and unaffected ears, and statistical analysis was done. The diameter of the bony canal of the cochlear nerve was significantly smaller in affected ears than in unaffected ears (P<0.01). The affected ears could be divided into groups with (72 ears) and without (46 ears) bony canal stenosis. Most (60%) of the patients with unilateral SNHL showed a significant difference in the diameters of the bony canals of the cochlear nerve between the affected and unaffected sides; moreover, the mean value was significantly smaller in affected ears. The diameter of <1.7 mm on transverse images or <1.8 mm on coronal images suggests hypoplasia. (author)

  18. SU-E-J-63: Estimating the Effects of Respiratory Motion On Dose Heterogeneity for ITV-Based Treatments

    Energy Technology Data Exchange (ETDEWEB)

    Williams, C; Lewis, J [Harvard Medical School, Cambridge, MA (United States); Brigham and Women' s Hospital, Boston, MA (United States)

    2014-06-01

    Purpose: To quantify the relationship between the amount of dose heterogeneity in a treatment plan that uses an internal target volume (ITV) to account for respiratory motion and the true amount of heterogeneity in the dose delivered to the tumor contained within that ITV. Methods: We develop a convolution-based framework for calculating dose delivered to a tumor moving inside an ITV according to a common sinusoid-based breathing model including asymmetry. We model the planned ITV dose distribution as a centrally peaked analytic function approximating the profile of clinical stereotactic body radiotherapy treatments. Expressions for the minimum and maximum dose received by the tumor are derived and evaluated for a range of clinically relevant parameters. Results of the model are validated with phantom measurements using an ion chamber array. Results: An analytic expression is presented for the maximum and minimum doses received by the tumor relative to the planned ITV dose. The tumor dose heterogeneity depends solely on the ratio of tumor size to ITV size, the peak dose in the planned ITV dose distribution, and the respiratory asymmetry parameter. Under the assumptions of this model, using a typical breathing asymmetry parameter and a dose distribution with a fixed size ITV covered by the 100% line and with a 130% hotspot, the maximum dose to the tumor varies between 113%–130%, and the minimum dose varies between 100%–116% depending on the amount of tumor motion. Conclusion: This modeling exercise demonstrates the interplay between motion and dose heterogeneity. Tumors that exhibit large amounts of respiratory motion relative to their size will receive a more homogeneous dose and a larger minimum dose than would be inferred from the ITV dose distribution. This effect is not captured in current clinical treatment planning methods unless 4D dose calculation techniques are used. This work was partially supported by a Varian Medical Systems research grant.

  19. SU-E-J-63: Estimating the Effects of Respiratory Motion On Dose Heterogeneity for ITV-Based Treatments

    International Nuclear Information System (INIS)

    Purpose: To quantify the relationship between the amount of dose heterogeneity in a treatment plan that uses an internal target volume (ITV) to account for respiratory motion and the true amount of heterogeneity in the dose delivered to the tumor contained within that ITV. Methods: We develop a convolution-based framework for calculating dose delivered to a tumor moving inside an ITV according to a common sinusoid-based breathing model including asymmetry. We model the planned ITV dose distribution as a centrally peaked analytic function approximating the profile of clinical stereotactic body radiotherapy treatments. Expressions for the minimum and maximum dose received by the tumor are derived and evaluated for a range of clinically relevant parameters. Results of the model are validated with phantom measurements using an ion chamber array. Results: An analytic expression is presented for the maximum and minimum doses received by the tumor relative to the planned ITV dose. The tumor dose heterogeneity depends solely on the ratio of tumor size to ITV size, the peak dose in the planned ITV dose distribution, and the respiratory asymmetry parameter. Under the assumptions of this model, using a typical breathing asymmetry parameter and a dose distribution with a fixed size ITV covered by the 100% line and with a 130% hotspot, the maximum dose to the tumor varies between 113%–130%, and the minimum dose varies between 100%–116% depending on the amount of tumor motion. Conclusion: This modeling exercise demonstrates the interplay between motion and dose heterogeneity. Tumors that exhibit large amounts of respiratory motion relative to their size will receive a more homogeneous dose and a larger minimum dose than would be inferred from the ITV dose distribution. This effect is not captured in current clinical treatment planning methods unless 4D dose calculation techniques are used. This work was partially supported by a Varian Medical Systems research grant

  20. The effects of spatial and temporal heterogeneity on the population dynamics of four animal species in a Danish landscape

    Directory of Open Access Journals (Sweden)

    Forchhammer Mads C

    2009-06-01

    Full Text Available Abstract Background Variation in carrying capacity and population return rates is generally ignored in traditional studies of population dynamics. Variation is hard to study in the field because of difficulties controlling the environment in order to obtain statistical replicates, and because of the scale and expense of experimenting on populations. There may also be ethical issues. To circumvent these problems we used detailed simulations of the simultaneous behaviours of interacting animals in an accurate facsimile of a real Danish landscape. The models incorporate as much as possible of the behaviour and ecology of skylarks Alauda arvensis, voles Microtus agrestis, a ground beetle Bembidion lampros and a linyphiid spider Erigone atra. This allows us to quantify and evaluate the importance of spatial and temporal heterogeneity on the population dynamics of the four species. Results Both spatial and temporal heterogeneity affected the relationship between population growth rate and population density in all four species. Spatial heterogeneity accounted for 23–30% of the variance in population growth rate after accounting for the effects of density, reflecting big differences in local carrying capacity associated with the landscape features important to individual species. Temporal heterogeneity accounted for 3–13% of the variance in vole, skylark and spider, but 43% in beetles. The associated temporal variation in carrying capacity would be problematic in traditional analyses of density dependence. Return rates were less than one in all species and essentially invariant in skylarks, spiders and beetles. Return rates varied over the landscape in voles, being slower where there were larger fluctuations in local population sizes. Conclusion Our analyses estimated the traditional parameters of carrying capacities and return rates, but these are now seen as varying continuously over the landscape depending on habitat quality and the mechanisms

  1. Shear zone nucleation and deformation transient: effect of heterogeneities and loading conditions in experimentally deformed calcite

    Science.gov (United States)

    Morales, L. F. G.; Rybacki, E.; Dresen, G. H.; Kilian, R.

    2015-12-01

    In the Earth's middle to lower crust, strain is frequently localized along ductile shear zones, which commonly nucleate at structural and material heterogeneities. To investigate shear zone nucleation and development due to heterogeneities, we performed constant strain-rate (CSR) and constant stress (CS) simple shear (torsion) deformation experiments on Carrara marble samples containing weak (limestone) inclusions. The experiments were conducted in a Paterson-type gas deformation apparatus at 900 °C temperature and 400 MPa confining pressure and maximum bulk shear strains of 3. Peak shear stress was about 20 MPa for all the samples, followed by smooth weakening and steady state behavior. The strain is predominantly localized in the host marble within the process zone in front of the inclusion, defined by a zone of intense grain size reduction due to dynamic recrystallization. In CS tests a narrow shear zone developed in front of the inclusion, whereas in CSR experiments the deformation is more heterogeneously distributed, up to g=3.. In the later, secondary foliations oblique to the process zone and alternating thin, high-strain layers are common. In samples deformed at the same shear strain (g=1), the average recrystallized grain size in the process zone is similar for CS and CSR conditions. Crystallographic preferred orientation (CPO) measurements shows that different grain sizes have slightly different CPO patterns. CPO strength varies for different grain sizes, with a CPO strength peak between 40-50 μm, decreasing progressively within smaller grain size, but with secondary peaks for different coarse-grained sizes. Our observations suggest that the initial formation and transient deformation of shear zones is strongly affected by loading conditions.

  2. Pattern of bony injuries among civilian gunshot victims at tertiary care hospital in Karachi, Pakistan

    Institute of Scientific and Technical Information of China (English)

    Ghulam Mustafa Kaim Khani; Syed Mujahid Humail; Kamran Hafeez; Naveed Ahmed

    2015-01-01

    Purpose:Firearm injuries impose a continuous economic burden on society and hospital resources.The aim of this study was to assess the pattern of bony injuries among victims of gunshots.Methods:A retrospective study was conducted in the Department of Orthopedics,Dow University of Health Sciences and Civil Hospital Karachi from January 2011 to December 2012.Patients with isolated bony injuries were included while patients with other systemic injuries were excluded.Results:There were 90 cases and the majority of them were male (84.4%).Mean age was (32,52 ± 10.27) years.Most of the patients (72.2%) belong to the younger age group.A low velocity weapon was used in 61 (67.8%) cases and a high velocity weapon was used in 29 (32.2%) cases.Armed robbery (64.4%) was the cause of conflict in more than half of the cases.Lower limb was involved in 72.2%.Fifty eight (64.4%) patients remained hospitalized for 15-20 days and others for more than 20 days.Internal fixation with intramedullary nailing was done in 35 patients while K-wire was used in 5 patients.Fifty patients were managed with external fixation,either uniplanar or multiplanar ilizarov.Deep wound infection and nonunion were observed more often in high velocity injuries.Conclusion:Armed robbery was the leading cause of gunshot bony injuries in our hospital.Young males were victimized in a majority of cases.High velocity injuries were associated with more complications.

  3. Meta-analysis of heterogeneous Down Syndrome data reveals consistent genome-wide dosage effects related to neurological processes

    Directory of Open Access Journals (Sweden)

    Pérez-Jurado Luis A

    2011-05-01

    Full Text Available Abstract Background Down syndrome (DS; trisomy 21 is the most common genetic cause of mental retardation in the human population and key molecular networks dysregulated in DS are still unknown. Many different experimental techniques have been applied to analyse the effects of dosage imbalance at the molecular and phenotypical level, however, currently no integrative approach exists that attempts to extract the common information. Results We have performed a statistical meta-analysis from 45 heterogeneous publicly available DS data sets in order to identify consistent dosage effects from these studies. We identified 324 genes with significant genome-wide dosage effects, including well investigated genes like SOD1, APP, RUNX1 and DYRK1A as well as a large proportion of novel genes (N = 62. Furthermore, we characterized these genes using gene ontology, molecular interactions and promoter sequence analysis. In order to judge relevance of the 324 genes for more general cerebral pathologies we used independent publicly available microarry data from brain studies not related with DS and identified a subset of 79 genes with potential impact for neurocognitive processes. All results have been made available through a web server under http://ds-geneminer.molgen.mpg.de/. Conclusions Our study represents a comprehensive integrative analysis of heterogeneous data including genome-wide transcript levels in the domain of trisomy 21. The detected dosage effects build a resource for further studies of DS pathology and the development of new therapies.

  4. Heterogeneous reactors

    International Nuclear Information System (INIS)

    The microscopic study of a cell is meant for the determination of the infinite multiplication factor of the cell, which is given by the four factor formula: K(infinite) = n(epsilon)pf. The analysis of an homogeneous reactor is similar to that of an heterogeneous reactor, but each factor of the four factor formula can not be calculated by the formulas developed in the case of an homogeneous reactor. A great number of methods was developed for the calculation of heterogeneous reactors and some of them are discussed. (Author)

  5. Effect of Substrate Character on Heterogeneous Ozone Reaction Rate with Individual PAHs and Their Reaction Mixtures

    Science.gov (United States)

    Holmen, B. A.; Stevens, T.

    2009-12-01

    Vehicle exhaust contains many unregulated chemical compounds that are harmful to human health and the natural environment, including polycyclic aromatic hydrocarbons (PAH), a class of organic compounds derived from fuel combustion that can be carcinogenic and mutagenic. PAHs have been quantified in vehicle-derived ultrafine particles (Dpfilter and (ii) NIST diesel PM. The difference in the PAH/O3 heterogeneous reaction rate resulting from the two substrates will be discussed. The experiments were completed by spiking a known PAH mixture to the solid, reacting the samples with gas-phase ozone, and determining both PAH loss over time and products formed, using thermal-desorption gas chromatography / mass spectrometry (TD-GC/MS). The individual PAHs anthracene, phenanthrene, and fluorene, adsorbed to a QFF were also separately reacted with 0.4 ppm ozone. A volatilization control and the collection of volatilized PAHs using a Tenax-packed thermal desorption vial completed the mass balance and aided determination parent-product relationships. Heterogeneous reaction products analyzed directly without derivatization indicate the formation of 9,10-anthracenedione, 9H-fluoren-9-one, and (1,1’-biphenyl)-2,2’-dicarboxaldehyde from the reaction of ozone with the PAH mix on a QFF, but only 9,10-anthracenedione was detected for the diesel PM reaction. The implications of these results for aging of diesel particulate in urban environments will be discussed.

  6. Effects of diffusion on total biomass in heterogeneous continuous and discrete-patch systems

    Science.gov (United States)

    DeAngelis, Don; Ming Ni, Wei; Zhang, Bo

    2016-01-01

    Theoretical models of populations on a system of two connected patches previously have shown that when the two patches differ in maximum growth rate and carrying capacity, and in the limit of high diffusion, conditions exist for which the total population size at equilibrium exceeds that of the ideal free distribution, which predicts that the total population would equal the total carrying capacity of the two patches. However, this result has only been shown for the Pearl-Verhulst growth function on two patches and for a single-parameter growth function in continuous space. Here, we provide a general criterion for total population size to exceed total carrying capacity for three commonly used population growth rates for both heterogeneous continuous and multi-patch heterogeneous landscapes with high population diffusion. We show that a sufficient condition for this situation is that there is a convex positive relationship between the maximum growth rate and the parameter that, by itself or together with the maximum growth rate, determines the carrying capacity, as both vary across a spatial region. This relationship occurs in some biological populations, though not in others, so the result has ecological implications.

  7. Effects of heterogeneous porous geology on ground-water flow and transport modeling in multiaquifer systems

    Energy Technology Data Exchange (ETDEWEB)

    Stephenson, D.E.; Duffield, G.M.; Buss, D.R.; Wadsworth, T.D.

    1989-01-01

    A three-dimensional model was used to investigate the influence of simple heterogeneities and discontinuities in an acquitard on ground-water flow and transport in a 17 mi/sup 2/ region of Savannah River Plant (SRP) where geologic and hydrologic control exists. Simple ''holes'' and faults in the confining bed were studied. These features produced variations in the distribution of hydraulic heads that could be difficult to detect without closely spaced monitoring wells in the vicinity of the feature. In terms of solute transport, however, significant changes in flow directions and rates resulted from the presence of the feature. The simulations showed that such heterogeneities and discontinuities can reverse flow directions near the feature and significantly reduce contaminant travel times to lower aquifers. The results of these model simulations indicate the importance of adequate geologic control for the accurate prediction of ground-water flowpaths in multiaquifer systems with implications for ground-water monitoring strategies, remedial system design, and risk assessments. 18 refs., 18 figs.

  8. Computational investigation of stoichiometric effects, binding site heterogeneities, and selectivities of molecularly imprinted polymers.

    Science.gov (United States)

    Terracina, Jacob J; Bergkvist, Magnus; Sharfstein, Susan T

    2016-06-01

    A series of quantum mechanical (QM) computational optimizations of molecularly imprinted polymer (MIP) systems were used to determine optimal monomer-to-target ratios. Imidazole- and xanthine-derived target molecules were studied. The investigation included both small-scale models (3-7 molecules) and larger-scale models (15-35 molecules). The optimal ratios differed between the small and larger scales. For the larger models containing multiple targets, binding-site surface area analysis was used to quantify the heterogeneity of these sites. The more fully surrounded sites had greater binding energies. No discretization of binding modes was seen, furthering arguments for continuous affinity distribution models. Molecular mechanical (MM) docking was then used to measure the selectivities of the QM-optimized binding sites. Selectivity was also shown to improve as binding sites become more fully encased by the monomers. For internal sites, docking consistently showed selectivity favoring the molecules that had been imprinted via QM geometry optimizations. The computationally imprinted sites were shown to exhibit size-, shape-, and polarity-based selectivity. Here we present a novel approach to investigate the selectivity and heterogeneity of imprinted polymer binding sites, by applying the rapid orientation screening of MM docking to the highly accurate QM-optimized geometries. Modeling schemes were designed such that no computing clusters or other specialized modeling equipment would be required. Improving the in silico analysis of MIP system properties will ultimately allow for the production of more sensitive and selective polymers. PMID:27207254

  9. Study of dosimetric effects due to metallic heterogeneity of tissue expanders in post-mastectomy radiotherapy

    International Nuclear Information System (INIS)

    Breast cancer is the most common cancer among women. In each year approximately 20% of the new cases of cancer in women are breast cancers. Despite the increase in the use of breast-conserving treatment, some women still require mastectomy as their primary surgical management. A large part of these women, whom undergo a mastectomy, realize a breast reconstruction afterwards. The most common options for reconstruction include autogenous tissue techniques and tissue expansion followed by breast implant placement. Many trials have demonstrated a survival benefit associated with post-mastectomy radiotherapy mainly if the treatment starts right after the mastectomy. In such case patients whom were realizing the breast reconstruction using tissue expanders can be irradiated using this. These patients posses a material with high atomic number within the irradiated area, so this metallic port becomes an heterogeneity which can modify the calculated doses distribution for the treatment. The study was due through the quantification of the relative transmission of 6MV and 15MV radiotherapy beam, making use of computer simulations with Monte Carlo method implemented by the MCNPX code. The results show that the presence of this metallic heterogeneity changes the transmission of the beam, causing a reduction up to 13% in the geometric shadowed region. According to dosimetric protocols, which recommend that the reduction in the dose should be bellow of 5%, the difference found in the study could be significant. (author)

  10. Bony fusion of the maxilla and mandible as a sequelae of noma: A rare case report

    International Nuclear Information System (INIS)

    Noma is a gangrenous disease of the orofacial region that leads to severe facial tissue destruction and is a significant cause of death among children. With the advent of modern antibiotics and improved nutrition, children with noma may survive into adulthood, but must face the challenge of undergoing repair of the sequelae of noma. This report describes a case of bony fusion of the maxilla and mandible in a 28-year-old female patient, which was a sequelae of a childhood case of noma

  11. Bony fusion of the maxilla and mandible as a sequelae of noma: A rare case report

    Energy Technology Data Exchange (ETDEWEB)

    Bagewadi, Shivanand B.; Awasthi, Ujjwala Rastogi; Mody, Bharat M.; Suma, Gundareddy N.; Garg, Shruti [Dept. of Medicine and Radiology, ITS Center for Dental Studies and Research, Ghaziabad, Uttar Pradesh (Korea, Republic of)

    2015-09-15

    Noma is a gangrenous disease of the orofacial region that leads to severe facial tissue destruction and is a significant cause of death among children. With the advent of modern antibiotics and improved nutrition, children with noma may survive into adulthood, but must face the challenge of undergoing repair of the sequelae of noma. This report describes a case of bony fusion of the maxilla and mandible in a 28-year-old female patient, which was a sequelae of a childhood case of noma.

  12. Enlargement of the bony orbit by orbital recurrence of choroidal melanoma 21 years after enucleation

    OpenAIRE

    Simonsz, Huib; Löffler, Karin

    1992-01-01

    textabstractA case is presented of a 58-year-old retarded male with a 6 cm, painless, hard, pigmented tumor filling the left orbit completely, after enucleation 21 years previously for retinal detachment, glaucoma and no light perception. CT scan and MRI revealed, besides the tumor, an outspoken enlargement of the bony orbit with thinning of the orbital walls. A biopsy showed a spindle B cell melanoma. In one of the paraffin histology sections of the globe enucleated 21 years previously a ver...

  13. Discount Window Lending: Policy Trade-offs and the 1985 BoNY Computer Failure

    OpenAIRE

    Ennis, Huberto M.; Price, David A.

    2015-01-01

    On November 21, 1985, the Bank of New York (BoNY) suffered a software failure that left it unable to redeliver securities it had received from other institutions as an intermediary. The result of the failure was that the bank sought and received $22.6 billion in discount window lending from the New York Fed, a record-setting amount. The episode presents a case study for considering when discount window lending and similar interventions are justified as a matter of efficiency, as well as the n...

  14. An Unusual Case of Bony Styloid Processes That Extend to the Hyoid Bone

    Directory of Open Access Journals (Sweden)

    Shekhar K. Gadkaree

    2015-01-01

    Full Text Available The embryological origin of the hyoid bone is a point of uncertainty, with controversy surrounding the relative contribution of the second pharyngeal arch to hyoid development. We encountered a 52-year-old male with bilateral bony styloid extension to the lesser cornu of the hyoid bone during the workup of a patient with laryngeal cancer. This embryological malformation clearly supports the hypothesis that the second pharyngeal arch gives rise to the lesser cornu and demonstrates an unusual clinical finding that may be encountered by otolaryngologists. We demonstrate the imaging findings and surgical management of this unusual anatomical variant and review the embryological basis for this rare malformation.

  15. Homogeneous and heterogeneous photoredox-catalyzed hydroxymethylation of ketones and keto esters: catalyst screening, chemoselectivity and dilution effects

    Directory of Open Access Journals (Sweden)

    Axel G. Griesbeck

    2014-05-01

    Full Text Available The homogeneous titanium- and dye-catalyzed as well as the heterogeneous semiconductor particle-catalyzed photohydroxymethylation of ketones by methanol were investigated in order to evaluate the most active photocatalyst system. Dialkoxytitanium dichlorides are the most efficient species for chemoselective hydroxymethylation of acetophenone as well as other aromatic and aliphatic ketones. Pinacol coupling is the dominant process for semiconductor catalysis and ketone reduction dominates the Ti(OiPr4/methanol or isopropanol systems. Application of dilution effects on the TiO2 catalysis leads to an increase in hydroxymethylation at the expense of the pinacol coupling.

  16. A combined PIV/LIF-system for the measurement of heterogeneous drag reduction effects in a pipe-flow

    Science.gov (United States)

    Saadeh, M.; Strauss, K.; Schneider, T.

    Particle Image Velocimetry (PIV) technique combined with flow visualization was applied in heterogeneous drag reduction to examine the motion of the polymer thread and the mixing process of polymer and water simultaneously at Reynolds numbers of 15000. The instantaneous velocity profiles for water/polymer motion showed in some cross-sections differences in the velocities of the two phases which indicates an interaction between the polymer thread and the water phase. The results of this interaction have not a significant effect on the drag reduction compared with the influence of the mixing process.

  17. Elimination of casting heterogeneities by high temperature heat treatment on a titanium stabilized austenitic alloy. Effect on the microstructure

    International Nuclear Information System (INIS)

    Microstructural observation on a longitudinal section of stainless steels often reveals the presence of a ''veined'' structure showing a segregation remainder due to the setting of the ingot. This casting heterogeneity can be eliminated by high temperature treatments. This study shows the change in the structure and the state of solubilization produced by these high temperature treatments and the effect of a stabilizing element such as titanium on Z6CNDT17.13 and Z10CNDT15.15B alloys compared with the Z6CND17.13 alloy. It is also shown that a high temperature treatment applied to these stabilized alloys deeply modifies the recrystallization kinetics

  18. Combined effects between temporal heterogeneity of water supply, nutrient level, and population density on biomass of four broadly distributed herbaceous species.

    Science.gov (United States)

    Hagiwara, Yousuke; Kachi, Naoki; Suzuki, Jun-Ichirou

    2012-01-01

    Temporal heterogeneity of water supply affects grassland community productivity and it can interact with nutrient level and intraspecific competition. To understand community responses, the responses of individual species to water heterogeneity must be evaluated while considering the interactions of this heterogeneity with nutrient levels and population density. We compared responses of four herbaceous species grown in monocultures to various combinations of water heterogeneity, nutrient level, and population density: two grasses (Cynodon dactylon and Lolium perenne), a forb (Artemisia princeps), and a legume (Trifolium repens). Treatment effects on shoot and root biomass were analyzed. In all four species, shoot biomass was larger under homogeneous than under heterogeneous water supply. Shoot responses of L. perenne tended to be greater at high nutrient levels. Although root biomass was also larger under homogeneous water supply, effects of water heterogeneity on root biomass were not significant in the grasses. Trifolium repens showed marked root responses, particularly at high population density. Although greater shoot and root growth under homogeneous water supply appears to be a general trend among herbaceous species, our results suggested differences among species could be found in the degree of response to water heterogeneity and its interactions with nutrient level and intraspecific competition. PMID:21327692

  19. Large epidemic thresholds emerge in heterogeneous networks of heterogeneous nodes

    CERN Document Server

    Yang, Hui; Gross, Thilo

    2015-01-01

    One of the famous results of network science states that networks with heterogeneous connectivity are more susceptible to epidemic spreading than their more homogeneous counterparts. In particular, in networks of identical nodes it has been shown that heterogeneity can lower the epidemic threshold at which epidemics can invade the system. Network heterogeneity can thus allow diseases with lower transmission probabilities to persist and spread. Here, we point out that for real world applications, this result should not be regarded independently of the intra-individual heterogeneity between people. Our results show that, if heterogeneity among people is taken into account, networks that are more heterogeneous in connectivity can be more resistant to epidemic spreading. We study a susceptible-infected-susceptible model with adaptive disease avoidance. Results from this model suggest that this reversal of the effect of network heterogeneity is likely to occur in populations in which the individuals are aware of t...

  20. Effect of tissue heterogeneity on an in vivo range verification technique for proton therapy

    Science.gov (United States)

    Hassane Bentefour, El; Shikui, Tang; Prieels, Damien; Lu, Hsiao-Ming

    2012-09-01

    It was proposed recently that time-resolved dose measurements during proton therapy treatment by passively scattered beams may be used for in vivo range verification. The method was shown to work accurately in a water tank. In this paper, we further evaluated the potential of the method for more clinically relevant situations where proton beams must pass through regions with significant tissue heterogeneities. Specifically, we considered prostate treatment where the use of anterior or anterior- oblique fields was recently proposed in order to reduce rectal dose by taking advantage of the sharp distal fall-off of the Bragg peak. These beam portals pass through various parts of pubic bone and potential air cavities in the bladder and bowels. Using blocks of materials with densities equivalent to bone, air, etc, arranged in the water tank in relevant configurations, we tested the robustness of the method against range shifting and range mixing. In the former, the beam range is changed uniformly by changes in tissue density in the beam path, while in the latter, variations in tissue heterogeneities across the beam cross section causes the mixing of beam energies downstream, as often occurs when the beam travels along the interface of materials with significantly different densities. We demonstrated that in the region of interest, the method can measure water-equivalent path length with accuracy better than ±0.5 mm for pure range shifting and still reasonable accuracy for range mixing between close beam energies. In situations with range mixing between significantly different beam energies, the dose rate profiles may be simulated for verifying the beam range. We also found that the above performances can be obtained with very small amount of dose (diodes are used as detectors. This makes the method suitable for in vivo range verification prior to each treatment delivery.

  1. The effects of heterogeneities and loading conditions in the development of shear zones

    Science.gov (United States)

    Morales, Luiz F. G.; Rybacki, Erik; Dresen, Georg

    2016-04-01

    Shear zones are regions of localized deformation and are frequently nucleated by material and/or structural heterogeneities and may develop under transient boundary conditions of strain rate and stress. Here we investigate shear zone nucleation and development due to mechanical heterogeneities. Experiments were performed in constant twist rate (CTR) and constant torque (CT) torsion tests to simulate the end member conditions of constant strain rate and constant stress. We have used hollow cylinders of Carrara marble samples containing weak inclusions of Solnhofen limestone. The experiments were conducted in a Paterson-type gas deformation apparatus at 900 °C temperature and 400 MPa confining pressure to maximum bulk shear strains of 3. Peak shear stress was about 20 MPa for all the samples, followed by smooth weakening and steady state behavior. The strain is predominantly localized in the host marble within the process zone in front of the inclusion, defined by a zone of intense grain size reduction due to dynamic recrystallization. Local shear strain values in the process zone are between 5 to 10 times higher than the bulk applied strain. In CT experiments, a narrow shear zone marked by intense grain size reduction is developed in front of the inclusion and the surrounding material remains relatively intact, whereas in CTR experiments the deformation is more widely distributed. The volume of recrystallized grains is nevertheless similar in the samples deformed at same bulk strains in both CT and CTR. At similar bulk strain, the crystallographic preferred orientation (CPO) in the process zone of CT experiments is stronger than in CTR experiments and CPO strength varies with grain size. Our observations suggest that the initial formation and transient deformation of shear zones is strongly affected by loading conditions.

  2. Effect of the population heterogeneity on growth behavior and its estimation

    Institute of Scientific and Technical Information of China (English)

    ZHANG HuaiQiang; LU LiLi; YAN XueLan; GAO PeiJi

    2007-01-01

    Different types of the Logistic model are constructed based on a simple assumption that the microbial populations are all composed of homogeneous members and consequently, the condition of design for the initial value of these models has to be rather limited in the case of N(t0)=N0. Therefore, these models cannot distinguish the dynamic behavior of the populations possessing the same N0 from heterogeneous phases. In fact, only a certain ratio of the cells in a population is dividing at any moment during growth progress, termed as θ, and thus, dN/dt not only depends on N, but also on θ. So θis a necessary element for the condition design of the initial value. Unfortunately, this idea has long been neglected in widely used growth models. However, combining together the two factors (N0 and θ) into the initial value often leads to the complexity in the mathematical solution. This difficulty can be overcome by using instantaneous rates (Vinst) to express growth progress. Previous studies in our laboratory suggested that the Vinst curve of the bacterial populations all showed a Guassian function shape and thus,the different growth phases can be reasonably distinguished. In the present study, the Gaussian distribution function was transformed approximately into an analytical form (Yi = αe[-0.5(xi-x0/b)2]) that can be conveniently used to evaluate the growth parameters and in this way the intrinsic growth behavior of a bacterial species growing in heterogeneous phases can be estimated. In addition, a new method has been proposed, in this case, the lag period and the double time for a bacterial population can also be reasonably evaluated. This approach proposed could thus be expected to reveal important insight of bacterial population growth. Some aspects in modeling population growth are also discussed.

  3. Effect of the population heterogeneity on growth behavior and its estimation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Different types of the Logistic model are constructed based on a simple assumption that the microbial populations are all composed of homogeneous members and consequently, the condition of design for the initial value of these models has to be rather limited in the case of N(t0)=N0. Therefore, these models cannot distinguish the dynamic behavior of the populations possessing the same N0 from heteroge-neous phases. In fact, only a certain ratio of the cells in a population is dividing at any moment during growth progress, termed as θ, and thus, ddNt not only depends on N, but also on θ. So θ is a necessary element for the condition design of the initial value. Unfortunately, this idea has long been neglected in widely used growth models. However, combining together the two factors (N0 and θ ) into the initial value often leads to the complexity in the mathematical solution. This difficulty can be overcome by using instantaneous rates (Vinst) to express growth progress. Previous studies in our laboratory sug-gested that the Vinst curve of the bacterial populations all showed a Guassian function shape and thus, the different growth phases can be reasonably distinguished. In the present study, the Gaussian dis-tribution function was transformed approximately into an analytical form (0.5x ibxYi αe=20) that can be conveniently used to evaluate the growth parameters and in this way the intrinsic growth behavior of a bacterial species growing in heterogeneous phases can be estimated. In addition, a new method has been proposed, in this case, the lag period and the double time for a bacterial population can also be reasonably evaluated. This approach proposed could thus be expected to reveal important insight of bacterial population growth. Some aspects in modeling population growth are also discussed.

  4. An alternative treatment option for a bony defect from large odontoma using recycled demineralization at chairside.

    Science.gov (United States)

    Lee, JuHyon; Lee, Eun-Young; Park, Eun-Jin; Kim, Eun-Suk

    2015-04-01

    Odontoma is the most common odontogenic benign tumor, and the treatment of choice is generally surgical removal. After excision, bone grafts may be necessary depending on the need for further treatment, or the size and location of the odontoma. Although the osteogenic capacity of a demineralized tooth was verified as early as 1967 by Urist and many other investigators, the cumbersome procedure, including a long demineralization time, may be less than comfortable for clinicians. A modified ultrasonic technology, with periodic negative pressure and temperature control, facilitated rapid and aseptic preparation of demineralized teeth for bone grafts. This approach reduces the demineralization time dramatically (≤80 minutes), so that the graft material can be prepared chairside on the same day as the extraction. The purpose of this article is to describe two cases of large compound odonotomas used as graft material prepared chairside for enucleation-induced bony defects. These two clinical cases showed favorable wound healing without complications, and good bony support for future dental implants or orthodontic treatment. Finally, this report will suggest the possibility of recycling the benign pathologic hard tissue as an alternative treatment option for conventional bone grafts in clinics. PMID:25922824

  5. Bony manifestation of rickets in a sunny city - a case report from Yazd, Iran

    Directory of Open Access Journals (Sweden)

    Mohammadhosain Afrand

    2014-01-01

    Full Text Available Rickets is disease that occurs in growing bones in which defective mineralization occurs in both the bone and the cartilage of the epiphyseal growth plate, resulting in the retardation of growth and skeletal deformities. Rickets is more common in areas with less sunlight. However, this case report presents a case of the bony manifestation of rickets with the intake of vitamin D supplements in Yazd, a city in central Iran that has sunshine almost every day. A patient was referred to an out-patient general pediatric clinic for deformities of the legs and growth disturbance, with his height far below the normal range. The changes that were most evident in his X-rays were the bowing of the long bones of the legs and forearms and the cupping of the wrist metaphyseal region. In summary, we present a patient with bony manifestation of rickets despite living in a sunny area and taking vitamin D supplements. Thus, it is important to remember that rickets is still a common disease among children in Iran. More studies of this issue should be conducted, including the identification of abnormal cases and rescheduling vitamin D supplementation programs.

  6. Esthetic Craniofacial Bony and Skull Base Reconstruction Using Flap Wrapping Technique.

    Science.gov (United States)

    Yano, Tomoyuki; Suesada, Nobuko; Usami, Satoshi

    2016-07-01

    For a safe and esthetic skull base reconstruction combined with repair of craniofacial bone defects, the authors introduce the flap wrapping technique in this study. This technique consists of skull base reconstruction using the vastus lateralis muscle of an anterolateral thigh (ALT) free flap, and structural craniofacial bony reconstruction using an autologous calvarial bone graft. The key to this technique is that all of the grafted autologous bone is wrapped with the vascularized fascia of the ALT free flap to protect the grafted bone from infection and exposure. Two anterior skull base tumors combined with craniofacial bony defects were included in this study. The subjects were a man and a woman, aged 18 and 64. Both patients had preoperative proton beam therapy. First, the skull base defect was filled with vastus lateralis muscle, and then structural reconstruction was performed with an autologous bone graft and a fabricated inner layer of calvarial bone, and then the grafted bone was completely wrapped in the vascularized fascia of the ALT free flap. By applying this technique, there was no intracranial infection or grafted bone exposure in these 2 patients postoperatively, even though both patients had preoperative proton beam therapy. Additionally, the vascularized fascia wrapped bone graft could provide a natural contour and prevent collapse of the craniofacial region, and this gives patients a better facial appearance even though they have had skull base surgery. PMID:27300454

  7. Application of Heterogeneous and Homogeneous Methods in the Calculation of Control-Rod Effects in D2O Lattices

    International Nuclear Information System (INIS)

    The application of heterogeneous and homogeneous calculation methods in the determination of control-rod effects in natural-uranium and heavy-water-moderated cores is discussed with reference to experiments performed in the Swedish RO. reactor. The experiments, involving the determination of the reactivity effects of both fully.and partially inserted absorber rods in different lattices, are used for comparison of the results of calculations in which (a) the individual control and fuel rods are treated by source-sink theory, and (b) the medium surrounding the control rods is treated as homogeneous. The agreements between the results from these theoretical treatments and the accuracy with which they predict the control-rod reactivity effects in heavy-water lattices are discussed. (author)

  8. Effect of temperature on the structure and phase behavior of water confined by hydrophobic, hydrophilic, and heterogeneous surfaces.

    Science.gov (United States)

    Giovambattista, Nicolas; Rossky, Peter J; Debenedetti, Pablo G

    2009-10-22

    We perform molecular dynamics simulations of water confined between atomically detailed hydrophobic, hydrophilic, and heterogeneous (patchy) nanoscale plates. We study the effects of temperature 220 isothermal compression, corresponding to paths of interest in protein denaturation. At a fixed temperature, water confined between hydrophobic plates can form vapor, liquid, or crystal (bilayer ice) phases, depending on the values of P and d. The P-d phase diagrams at T = 300 K and T = 220 K show that cooling suppresses the vapor phase and stabilizes the liquid and crystal phases. The critical separation d(c)(P), below which vapor forms, shifts to lower values of d and P upon cooling. The density profiles show that, upon cooling, water approaches the hydrophobic plates. Hence, the effective hydrophobicity of the plate decreases as T decreases, consistent with the suppression of the vapor phase upon cooling. However, both the orientation of water's molecules at the interface and the water contact angle on the hydrophobic surface show practically no temperature dependence. Simulations of water confined by heterogeneous plates decorated with hydrophobic and hydrophilic patches reveal that cooling leads to appreciable blurring of the differences between water densities at hydrophobic and hydrophilic surfaces. This observation, together with remarkable similarities in confined water's response to isobaric cooling and to isothermal compression, suggests that the invasion of hydrophobic cavities by water is an important mechanism underlying both pressure and cold denaturation of proteins. PMID:19435300

  9. Stock index realized volatility forecasting in the presence of heterogeneous leverage effects and long range dependence in the volatility of realized volatility

    OpenAIRE

    Louzis, Dimitrios; Xanthopoulos-Sisinis, Spyros; Refenes, Apostolos

    2011-01-01

    Abstract In this article, we account for the presence of heterogeneous leverage effects and the persistence in the volatility of stock index realized volatility. The Heterogeneous Autoregressive (HAR) realized volatility model is extended in order to account for asymmetric responses to negative and positive shocks occurring at distinct frequencies, as well as, for the long range dependence in the heteroscedastic variance of the residuals. Compared with established HAR and Autoregre...

  10. Inclusion of line tension effect in classical nucleation theory for heterogeneous nucleation: A rigorous thermodynamic formulation and some unique conclusions

    International Nuclear Information System (INIS)

    A rigorous thermodynamic formulation of the geometric model for heterogeneous nucleation including line tension effect is missing till date due to the associated mathematical hurdles. In this work, we develop a novel thermodynamic formulation based on Classical Nucleation Theory (CNT), which is supposed to illustrate a systematic and a more plausible analysis for the heterogeneous nucleation on a planar surface including the line tension effect. The appreciable range of the critical microscopic contact angle (θc), obtained from the generalized Young’s equation and the stability analysis, is θ∞ < θc < θ′ for positive line tension and is θM < θc < θ∞ for negative line tension. θ∞ is the macroscopic contact angle, θ′ is the contact angle for which the Helmholtz free energy has the minimum value for the positive line tension, and θM is the local minima of the nondimensional line tension effect for the negative line tension. The shape factor f, which is basically the dimensionless critical free energy barrier, becomes higher for lower values of θ∞ and higher values of θc for positive line tension. The combined effect due to the presence of the triple line and the interfacial areas (fL + fS) in shape factor is always within (0, 3.2), resulting f in the range of (0, 1.7) for positive line tension. A formerly presumed appreciable range for θc(0 < θc < θ∞) is found not to be true when the effect of negative line tension is considered for CNT. Estimation based on the property values of some real fluids confirms the relevance of the present analysis

  11. Isolating Effects of Water Table Dynamics, Terrain, and Soil Moisture Heterogeneity on the Atmospheric Boundary Layer Using Coupled Models

    Science.gov (United States)

    Rihani, Jehan Fouad

    Previous observational and modeling studies have demonstrated the sensitivity of atmospheric processes to land surface and subsurface conditions. The extent of the connection between these processes, however, is not yet fully understood. A sufficient understanding is needed of the circumstances under which these coupled processes might play a more significant role and when they might be simplified into the decoupled systems so frequently modeled in practice. This work focuses on the effects of terrain and soil moisture heterogeneity in changing water table depth and energy fluxes at the land surface, and how this might impact the development and structure of the atmospheric boundary layer. A three-dimensional, variably saturated groundwater model coupled to a three dimensional mesoscale atmospheric model (PF.ARPS) is used here to study the two-way feedback between the subsurface, land-surface, and atmosphere for both idealized cases and a real watershed. This is done by addressing the following key questions: How do terrain, soil moisture heterogeneity, and subsurface properties affect the planetary boundary layer? What are the effects of water table depth on land surface fluxes and boundary layer development and depth? What times of the diurnal cycle and which locations within a watershed demonstrate stronger feedbacks between the subsurface and the atmosphere? These questions are first addressed for idealized simulations designed to illustrate subsurface-surface feedbacks on one hand, and land-atmosphere feedbacks on the other hand. The coupled hydrologic model is then used to simulate real conditions over the Little Washita watershed in Oklahoma with the goal of addressing the above questions for a real watershed, and exploring the two-way feedback between the atmospheric boundary layer and the water table. The coupled simulations are compared to non-coupled atmospheric simulations initialized with simplified and realistic soil moisture profiles. Effects of a

  12. Effect of surface free energies on the heterogeneous nucleation of water droplet: A molecular dynamics simulation approach

    Science.gov (United States)

    Xu, W.; Lan, Z.; Peng, B. L.; Wen, R. F.; Ma, X. H.

    2015-02-01

    Heterogeneous nucleation of water droplet on surfaces with different solid-liquid interaction intensities is investigated by molecular dynamics simulation. The interaction potentials between surface atoms and vapor molecules are adjusted to obtain various surface free energies, and the nucleation process and wetting state of nuclei on surfaces are investigated. The results indicate that near-constant contact angles are already established for nano-scale nuclei on various surfaces, with the contact angle decreasing with solid-liquid interaction intensities linearly. Meanwhile, noticeable fluctuation of vapor-liquid interfaces can be observed for the nuclei that deposited on surfaces, which is caused by the asymmetric forces from vapor molecules. The formation and growth rate of nuclei are increasing with the solid-liquid interaction intensities. For low energy surface, the attraction of surface atoms to water molecules is comparably weak, and the pre-existing clusters can depart from the surface and enter into the bulk vapor phase. The distribution of clusters within the bulk vapor phase becomes competitive as compared with that absorbed on surface. For moderate energy surfaces, heterogeneous nucleation predominates and the formation of clusters within bulk vapor phase is suppressed. The effect of high energy particles that embedded in low energy surface is also discussed under the same simulation system. The nucleation preferably initiates on the high energy particles, and the clusters that formed on the heterogeneous particles are trapped around their original positions instead of migrating around as that observed on smooth surfaces. This feature makes it possible for the heterogeneous particles to act as fixed nucleation sites, and simulation results also suggest that the number of nuclei increases monotonously with the number of high energy particles. The growth of nuclei on high energy particles can be divided into three sub-stages, beginning with the formation

  13. Effects of dispersal on total biomass in a patchy, heterogeneous system: Analysis and experiment.

    Science.gov (United States)

    Zhang, Bo; Liu, Xin; DeAngelis, D L; Ni, Wei-Ming; Wang, G Geoff

    2015-06-01

    An intriguing recent result from mathematics is that a population diffusing at an intermediate rate in an environment in which resources vary spatially will reach a higher total equilibrium biomass than the population in an environment in which the same total resources are distributed homogeneously. We extended the current mathematical theory to apply to logistic growth and also showed that the result applies to patchy systems with dispersal among patches, both for continuous and discrete time. This allowed us to make specific predictions, through simulations, concerning the biomass dynamics, which were verified by a laboratory experiment. The experiment was a study of biomass growth of duckweed (Lemna minor Linn.), where the resources (nutrients added to water) were distributed homogeneously among a discrete series of water-filled containers in one treatment, and distributed heterogeneously in another treatment. The experimental results showed that total biomass peaked at an intermediate, relatively low, diffusion rate, higher than the total carrying capacity of the system and agreeing with the simulation model. The implications of the experiment to dynamics of source, sink, and pseudo-sink dynamics are discussed. PMID:25817196

  14. Sensing Home: A Cost-Effective Design for Smart Home via Heterogeneous Wireless Networks.

    Science.gov (United States)

    Fan, Xiaohu; Huang, Hao; Qi, Shipeng; Luo, Xincheng; Zeng, Jing; Xie, Qubo; Xie, Changsheng

    2015-01-01

    The aging population has inspired the marketing of advanced real time devices for home health care, more and more wearable devices and mobile applications, which have emerged in this field. However, to properly collect behavior information, accurately recognize human activities, and deploy the whole system in a real living environment is a challenging task. In this paper, we propose a feasible wireless-based solution to deploy a data collection scheme, activity recognition model, feedback control and mobile integration via heterogeneous networks. We compared and found a suitable algorithm that can be run on cost-efficient embedded devices. Specifically, we use the Super Set Transformation method to map the raw data into a sparse binary matrix. Furthermore, designed front-end devices of low power consumption gather the living data of the habitant via ZigBee to reduce the burden of wiring work. Finally, we evaluated our approach and show it can achieve a theoretical time-slice accuracy of 98%. The mapping solution we propose is compatible with more wearable devices and mobile apps. PMID:26633424

  15. Sensing Home: A Cost-Effective Design for Smart Home via Heterogeneous Wireless Networks

    Directory of Open Access Journals (Sweden)

    Xiaohu Fan

    2015-12-01

    Full Text Available The aging population has inspired the marketing of advanced real time devices for home health care, more and more wearable devices and mobile applications, which have emerged in this field. However, to properly collect behavior information, accurately recognize human activities, and deploy the whole system in a real living environment is a challenging task. In this paper, we propose a feasible wireless-based solution to deploy a data collection scheme, activity recognition model, feedback control and mobile integration via heterogeneous networks. We compared and found a suitable algorithm that can be run on cost-efficient embedded devices. Specifically, we use the Super Set Transformation method to map the raw data into a sparse binary matrix. Furthermore, designed front-end devices of low power consumption gather the living data of the habitant via ZigBee to reduce the burden of wiring work. Finally, we evaluated our approach and show it can achieve a theoretical time-slice accuracy of 98%. The mapping solution we propose is compatible with more wearable devices and mobile apps.

  16. Sensing Home: A Cost-Effective Design for Smart Home via Heterogeneous Wireless Networks

    Science.gov (United States)

    Fan, Xiaohu; Huang, Hao; Qi, Shipeng; Luo, Xincheng; Zeng, Jing; Xie, Qubo; Xie, Changsheng

    2015-01-01

    The aging population has inspired the marketing of advanced real time devices for home health care, more and more wearable devices and mobile applications, which have emerged in this field. However, to properly collect behavior information, accurately recognize human activities, and deploy the whole system in a real living environment is a challenging task. In this paper, we propose a feasible wireless-based solution to deploy a data collection scheme, activity recognition model, feedback control and mobile integration via heterogeneous networks. We compared and found a suitable algorithm that can be run on cost-efficient embedded devices. Specifically, we use the Super Set Transformation method to map the raw data into a sparse binary matrix. Furthermore, designed front-end devices of low power consumption gather the living data of the habitant via ZigBee to reduce the burden of wiring work. Finally, we evaluated our approach and show it can achieve a theoretical time-slice accuracy of 98%. The mapping solution we propose is compatible with more wearable devices and mobile apps. PMID:26633424

  17. The effect of mesostructure heterogeneity on cracks initiation and the displacement distribution in NCF composites

    International Nuclear Information System (INIS)

    Non Crimp Fabrics (NCF) are promising new generation composite materials. They are now being used in some sections of composite industry, for example in wind turbine blades and boat hulls. The aerospace industry also shows an increasing interest in this material, thanks to the low cost of its manufacturing process. NCFs are special types of textile composites, made of layers of parallel fiber bundles oriented in different directions and separated by resin. Due to the manufacturing process the fiber bundles are not perfectly straight. They show a certain degree of waviness which decreases the stiffness and the strength of the material. The heterogeneous mesostructure affects the mechanical properties of the material and the failure mechanisms. This was studied using both numerical and experimental methods. In our experimental approach, a carbon fiber/epoxy resin laminate with uniform fiber distribution was manufactured by voluntarily introducing waviness to simulate the NCF composites. The displacement map was studied against the thickness of a sample loaded in tension, using ESPI (Electronic Speckle Pattern Interferometry). This can give us a primary idea of the micro damage initiation and the cracks' shapes.

  18. Computer animation as a tool to visualize effects of seismic wave propagation inside heterogeneous media

    Directory of Open Access Journals (Sweden)

    P. Lanucara

    2000-06-01

    Full Text Available A technique to make computer animations representing the propagation of antiplane shear waves in heterogeneous dissipative media is presented. The aim is to develop a useful tool to better investigate the physics of site effectsin the 2D approximation. We apply this technique to real case studies that were the subject of previous papers. For each case study a movie has been made to illustrate the wavefield time evolution and its interaction with the geological structure. All the movies can be seen and downloaded at the web site http://sigfrido.ingrm.it/movies.html. The paper shows the most representative frames of movies, providing an overview of the role played by the topographic irregularities and the geometry of internal discontinuities in trapping and focusing energy. The details of the dynamics are well visualized through movies. Particular attention is devoted to the representation of simulated ground motion in sediment-filled basins under resonance conditions. Problems related to color scales and frame normalization are analysed and discussed.

  19. Effect of the heterogeneity of texture on the shape memory of laminated Fe-Mn-Si alloys

    International Nuclear Information System (INIS)

    A Fe-30Mn-4Si shape memory alloy was studied in order to clarify the effect of the cutting deformation on the texture of the volume, during laminating in two different thermomechanical conditions. The X-ray analysis showed heterogeneity in the texture throughout the thickness of the laminated sheets, from the friction between the sheet and the rollers. The neutron diffraction revealed that these textured layers affect the full volume. The surface texture of the alloy processed at 600oC, is the most favorable one for martensitic γ→ε transformation that creates the shape memory effect. Comparing these results with those obtained in sheets laminated at room temperature, the gradient of cut deformations was observed to produce changes in the texture of the material's volume. The traction tests initially induce the martensitic transformation in favorably positioned grains. As a result, these favorable positions disappear in the remaining austenite

  20. Investigations into effects of blade number in a booster blower for forced ventilation on noise level caused by stream heterogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Sowa, A.

    1985-09-01

    Noise level is analyzed caused by WLE-603A booster mine blowers used for local ventilation in underground coal mines in Poland. The blowers have two impellers rotating in opposite directions. One impeller is equipped with 10 or 11 blades, the other with 9, 8, 7, 6 or 5 blades. Revolution rate of 2940 rpm is used. A formula for optimizing blade number on two impellers and the relation of impeller number is derived. Effects of optimizing blade number on the air streams produced by two impellers and their interaction are analyzed. Effects of stream heterogeneity on noise level are determined. Recommendations for the optimum blade number which reduces noise level are made. 3 references.

  1. Enhancement of Bacterial Transport in Aerobic and Anaerobic Environments: Assessing the Effect of Metal Oxide Chemical Heterogeneities

    International Nuclear Information System (INIS)

    The goal of our research was to understand the fundamental processes that control microbial transport in physically and chemically heterogeneous aquifers and from this enhanced understanding determine the requirements for successful, field-scale delivery of microorganisms to metal contaminated subsurface sites. Our specific research goals were to determine; (1) the circumstances under which the preferential adsorption of bacteria to Fe, Mn, and Al oxyhydroxides influences field-scale bacterial transport, (2) the extent to which the adhesion properties of bacterial cells affect field-scale bacterial transport, (3) whether microbial Fe(III) reduction can enhance field-scale transport of Fe reducing bacteria (IRB) and other microorganisms and (4) the effect of field-scale physical and chemical heterogeneity on all three processes. Some of the spin-offs from this basic research that can improve biostimulation and bioaugmentation remediation efforts at contaminated DOE sites have included; (1) new bacterial tracking tools for viable bacteria; (2) an integrated protocol which combines subsurface characterization, laboratory-scale experimentation, and scale-up techniques to accurately predict field-scale bacterial transport; and (3) innovative and inexpensive field equipment and methods that can be employed to enhance Fe(III) reduction and microbial transport and to target microbial deposition under both aerobic and anaerobic conditions

  2. An Uncertainty Quantification Framework for Studying the Effect of Spatial Heterogeneity in Reservoir Permeability on CO2 Sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Zhangshuan; Engel, David W.; Lin, Guang; Fang, Yilin; Fang, Zhufeng

    2013-10-01

    In this paper, we introduce an uncertainty quantification (UQ) software framework for carbon sequestration, focused on the effect of spatial heterogeneity of reservoir properties on CO2 migration. We use a sequential Gaussian method (SGSIM) to generate realizations of permeability fields with various spatial statistical attributes. To deal with the computational difficulties, we integrate the following ideas/approaches. First, we use three different sampling approaches (probabilistic collocation, quasi-Monte Carlo, and adaptive sampling) to reduce the number of forward calculations while trying to explore the parameter space and quantify the input uncertainty. Second, we use eSTOMP as the forward modeling simulator. eSTOMP is implemented with the Global Arrays toolkit that is based on one-sided inter-processor communication and supports a shared memory programming style on distributed memory platforms, providing a highly-scalable performance. Third, we built an adaptive system infrastructure to select the best possible data transfer mechanisms, to optimally allocate system resources to improve performance and to integrate software packages and data for composing carbon sequestration simulation, computation, analysis, estimation and visualization. We demonstrate the framework with a given CO2 injection scenario in heterogeneous sandstone reservoirs.

  3. Effects of mechanical heterogeneity on the tensile and fatigue behaviours in a laser-arc hybrid welded aluminium alloy joint

    International Nuclear Information System (INIS)

    Highlights: • Full field strain evolution was characterized using DIC method in fatigue test. • The differences of fatigue failure mechanism between HAZ and FZ were discussed. • Porosity in FZ significantly influenced high cycle fatigue behaviours of the weld. - Abstract: The effects of mechanical heterogeneity on the tensile and high cycle fatigue (104–107 cycles) properties were investigated for laser-arc hybrid welded aluminium alloy joints. Tensile–tensile cyclic loading with a stress ratio of 0.1 was applied in a direction perpendicular to the weld direction for up to 107 cycles. The local mechanical properties in the tensile test and the accumulated plastic strain in the fatigue test throughout the weld’s different regions were characterized using a digital image correlation technique. The tensile results indicated heterogeneous tensile properties throughout the different regions of the aluminium welded joint, and the heat affected zone was the weakest region in which the strain localized. In the fatigue test, the accumulated plastic strain evolutions in different subzones of the weld were analyzed, and slip bands could be clearly observed in the heat affected zone. A transition of fatigue failure locations from the heat affected zone caused by accumulated plastic strain to the fusion zone induced by fatigue crack at pores could be observed under different cyclic stress levels. The welding porosity in the fusion zone significantly influences the high cycle fatigue behaviour

  4. Interconnecting heterogeneous database management systems

    Science.gov (United States)

    Gligor, V. D.; Luckenbaugh, G. L.

    1984-01-01

    It is pointed out that there is still a great need for the development of improved communication between remote, heterogeneous database management systems (DBMS). Problems regarding the effective communication between distributed DBMSs are primarily related to significant differences between local data managers, local data models and representations, and local transaction managers. A system of interconnected DBMSs which exhibit such differences is called a network of distributed, heterogeneous DBMSs. In order to achieve effective interconnection of remote, heterogeneous DBMSs, the users must have uniform, integrated access to the different DBMs. The present investigation is mainly concerned with an analysis of the existing approaches to interconnecting heterogeneous DBMSs, taking into account four experimental DBMS projects.

  5. The bony labyrinth of the middle Pleistocene Sima de los Huesos hominins (Sierra de Atapuerca, Spain).

    Science.gov (United States)

    Quam, Rolf; Lorenzo, Carlos; Martínez, Ignacio; Gracia-Téllez, Ana; Arsuaga, Juan Luis

    2016-01-01

    We performed 3D virtual reconstructions based on CT scans to study the bony labyrinth morphology in 14 individuals from the large middle Pleistocene hominin sample from the site of the Sima de los Huesos (SH) in the Sierra de Atapuerca in northern Spain. The Atapuerca (SH) hominins represent early members of the Neandertal clade and provide an opportunity to compare the data with the later in time Neandertals, as well as Pleistocene and recent humans more broadly. The Atapuerca (SH) hominins do not differ from the Neandertals in any of the variables related to the absolute and relative sizes and shape of the semicircular canals. Indeed, the entire Neandertal clade seems to be characterized by a derived pattern of canal proportions, including a relatively small posterior canal and a relatively large lateral canal. In contrast, one of the most distinctive features observed in Neandertals, the low placement of the posterior canal (i.e., high sagittal labyrinthine index), is generally not present in the Atapuerca (SH) hominins. This low placement is considered a derived feature in Neandertals and is correlated with a more vertical orientation of the ampullar line (LSCm  PPp), and third part of the facial canal (LSCm < FC3). Some variation is present within the Atapuerca (SH) sample, however, with a few individuals approaching the Neandertal condition more closely. In addition, the cochlear shape index in the Atapuerca (SH) hominins is low, indicating a reduction in the height of the cochlea. Although the phylogenetic polarity of this feature is less clear, the low shape index in the Atapuerca (SH) hominins may be a derived feature. Regardless, cochlear height subsequently increased in Neandertals. In contrast to previous suggestions, the expanded data in the present study indicate no difference across the genus Homo in the angle of inclination of the cochlear basal turn (COs < LSCm). Principal components analysis largely confirms these observations. While not

  6. Heterogeneity in mammography use across the nation: separating evidence of disparities from the disproportionate effects of geography

    Directory of Open Access Journals (Sweden)

    Clayton Laurel

    2008-06-01

    Full Text Available Abstract Background Mammography is essential for early detection of breast cancer and both reduced morbidity and increased survival among breast cancer victims. Utilization is lower than national guidelines, and evidence of a recent decline in mammography use has sparked concern. We demonstrate that regression models estimated over pooled samples of heterogeneous states may provide misleading information regarding predictors of health care utilization and that comprehensive cancer control efforts should focus on understanding these differences and underlying causal factors. Our study population includes all women over age 64 with breast cancer in the Surveillance Epidemiology and End Results (SEER cancer registries, linked to a nationally representative 5% reference sample of Medicare-eligible women located in 11 states that span all census regions and are heterogeneous in racial and ethnic mix. Combining women with and without cancer in the sample allows assessment of previous cancer diagnosis on propensity to use mammography. Our conceptual model recognizes the interplay between individual, social, cultural, and physical environments along the pathways to health care utilization, while delineating local and more distant levels of influence among contextual variables. In regression modeling, we assess individual-level effects, direct effects of contextual factors, and interaction effects between individual and contextual factors. Results Pooling all women across states leads to quite different conclusions than state-specific models. Commuter intensity, community acculturation, and community elderly impoverishment have significant direct impacts on mammography use which vary across states. Minorities living in isolated enclaves with others of the same race/ethnicity may be either advantaged or disadvantaged, depending upon the place studied. Conclusion Careful analysis of place-specific context is essential for understanding differences across

  7. Heterogeneous in vitro effects of doxorubicin on gene expression in primary human liposarcoma cultures

    Directory of Open Access Journals (Sweden)

    Hans-Ulrich Steinau

    2008-10-01

    Full Text Available Abstract Background Doxorubicin is considered one of the most potent established chemotherapeutics in the treatment of liposarcoma; however, the response rates usually below 30%, are still disappointing. This study was performed to identify gene expression changes in liposarcoma after doxorubicin treatment. Methods Cells of 19 primary human liposarcoma were harvested intraoperatively and brought into cell culture. Cells were incubated with doxorubicin for 24 h, RNA was isolated and differential gene expression was analysed by the microarray technique. Results A variety of genes involved in apoptosis were up and down regulated in different samples revealing a heterogeneous expression pattern of the 19 primary tumor cell cultures in response to doxorubicin treatment. However, more than 50% of the samples showed up-regulation of pro-apoptotic genes such as TRAIL Receptor2, CDKN1A, GADD45A, FAS, CD40, PAWR, NFKBIA, IER3, PSEN1, RIPK2, and CD44. The anti-apoptotic genes TNFAIP3, PEA15, Bcl2A1, NGFB, and BIRC3 were also up-regulated. The pro-apoptotic CD14, TIA1, and ITGB2 were down-regulated in more than 50% of the tumor cultures after treatment with doxorubicin, as was the antiapoptotic YWHAH. Conclusion Despite a correlation of the number of differentially regulated genes to the tumor grading and to a lesser extent histological subtype, the expression patterns varied strongly; however, especially among high grade tumors the responses of selected apoptosis genes were similar. The predescribed low clinical response rates of low grade liposarcoma to doxorubicin correspond to our results with only little changes on gene expression level and also divergent findings concerning the up- and down-regulation of single genes in the different sarcoma samples.

  8. Heterogeneous in vitro effects of doxorubicin on gene expression in primary human liposarcoma cultures

    International Nuclear Information System (INIS)

    Doxorubicin is considered one of the most potent established chemotherapeutics in the treatment of liposarcoma; however, the response rates usually below 30%, are still disappointing. This study was performed to identify gene expression changes in liposarcoma after doxorubicin treatment. Cells of 19 primary human liposarcoma were harvested intraoperatively and brought into cell culture. Cells were incubated with doxorubicin for 24 h, RNA was isolated and differential gene expression was analysed by the microarray technique. A variety of genes involved in apoptosis were up and down regulated in different samples revealing a heterogeneous expression pattern of the 19 primary tumor cell cultures in response to doxorubicin treatment. However, more than 50% of the samples showed up-regulation of pro-apoptotic genes such as TRAIL Receptor2, CDKN1A, GADD45A, FAS, CD40, PAWR, NFKBIA, IER3, PSEN1, RIPK2, and CD44. The anti-apoptotic genes TNFAIP3, PEA15, Bcl2A1, NGFB, and BIRC3 were also up-regulated. The pro-apoptotic CD14, TIA1, and ITGB2 were down-regulated in more than 50% of the tumor cultures after treatment with doxorubicin, as was the antiapoptotic YWHAH. Despite a correlation of the number of differentially regulated genes to the tumor grading and to a lesser extent histological subtype, the expression patterns varied strongly; however, especially among high grade tumors the responses of selected apoptosis genes were similar. The predescribed low clinical response rates of low grade liposarcoma to doxorubicin correspond to our results with only little changes on gene expression level and also divergent findings concerning the up- and down-regulation of single genes in the different sarcoma samples

  9. Geometric effects in microfluidics on heterogeneous cell stress using an Eulerian-Lagrangian approach.

    Science.gov (United States)

    Warren, K M; Mpagazehe, J N; LeDuc, P R; Higgs, C F

    2016-02-01

    The response of individual cells at the micro-scale in cell mechanics is important in understanding how they are affected by changing environments. To control cell stresses, microfluidics can be implemented since there is tremendous control over the geometry of the devices. Designing microfluidic devices to induce and manipulate stress levels on biological cells can be aided by computational modeling approaches. Such approaches serve as an efficient precursor to fabricating various microfluidic geometries that induce predictable levels of stress on biological cells, based on their mechanical properties. Here, a three-dimensional, multiphase computational fluid dynamics (CFD) modeling approach was implemented for soft biological materials. The computational model incorporates the physics of the particle dynamics, fluid dynamics and solid mechanics, which allows us to study how stresses affect the cells. By using an Eulerian-Lagrangian approach to treat the fluid domain as a continuum in the microfluidics, we are conducting studies of the cells' movement and the stresses applied to the cell. As a result of our studies, we were able to determine that a channel with periodically alternating columns of obstacles was capable of stressing cells at the highest rate, and that microfluidic systems can be engineered to impose heterogenous cell stresses through geometric configuring. We found that when using controlled geometries of the microfluidics channels with staggered obstructions, we could increase the maximum cell stress by nearly 200 times over cells flowing through microfluidic channels with no obstructions. Incorporating computational modeling in the design of microfluidic configurations for controllable cell stressing could help in the design of microfludic devices for stressing cells such as cell homogenizers. PMID:26753780

  10. Check-list of bony fish collected from the Upper Halda River, Chittagong, Bangladesh

    Directory of Open Access Journals (Sweden)

    Mohammed S. Alam

    2013-07-01

    Full Text Available The Halda River of Bangladesh gains its importance as natural spawning ground of major carpfishes. A check-list of bony fish in the Halda River was carried out. It appeared that the fish fauna in thisriver is dominated by the family of Cyprinidae (28.57 % represented by 18 species, followed byGobiidae (9.52 % represented by 6 species and Schibeidae (7.94 % with 5 species, than Bagridae andChannidae (6.35 % with 4 species each, Siluridae (4.76 % with 3 species. Among the listed families,there are 14 families represented by a single species and 4 families by 2 species. The total number ofspecies is 63 belonging to 51 genera pertaining to 24 families and 9 orders. The present study reported 5migrant species from the Bay of Bengal and 3 species as exotic species.

  11. Syringocystadenoma Papilliferum of the Bony External Auditory Canal: A Rare Tumor in a Rare Location

    Directory of Open Access Journals (Sweden)

    Anastasija Arechvo

    2013-01-01

    Full Text Available Tumors originating from ceruminous glands are rare lesions of the external auditory canal. The lack of specific clinical and radiological signs makes their diagnosis challenging. We report the case of an exceptionally rare benign tumor, a syringocystadenoma papilliferum (SCAP, in an atypical location in the bony segment of the external auditory canal with uncommon clinical signs. The special traits of the case included the following: the most lateral component of the tumor was macroscopically cystic and a granular myringitis with an obstructing keratin mass plug was observed behind the mass. The clinical, audiological, radiological, and histological characteristics of the neoplasm are consequently presented. Intraoperative diagnosis of the epidermal cyst was proposed. The final diagnosis of SCAP was determined only by histological analysis after the surgical excision. The educational aspects of the case are critically discussed.

  12. The bony crescent sign - a new sign of facial nerve schwannoma

    International Nuclear Information System (INIS)

    Schwannomas are relatively uncommon intracranial tumours. They most commonly involve the acoustic nerve followed in frequency by the trigeminal nerve. Other cranial nerves are rarely involved. Facial nerve schwannomas occurring within the petrous temporal bone are very rare. Their diagnosis may be missed prospectively even when appropriate computerized tomography (CT) scans are performed. Even in retrospect the site of abnormality may be difficult to identify, especially if there is an associated middle ear mass such as a cholesteatoma. In the 4 cases presented the facial nerve schwannoma was seen on high resolution CT as a soft tissue mass bounded anteriorly by a thin rim of bone. This bony crescent sign is a previously undescribed feature of facial nerve schwannoma which appears to be strongly indicative of the presence of this tumour. Recognition of this sign makes these tumours arising in the region of the geniculate ganglion easy to diagnose prospectively. 12 refs., 6 figs

  13. A clinico-radiologic study of bony remodeling of the fractured condyles in children

    International Nuclear Information System (INIS)

    Bony remodeling pattern of condyle fractures in children are different from in adult for growing of condyle, also might affect treatment and prognosis of the condyle fracture. Subjects of this clinical and radiologic study were 26 temporomandibular joints diagnosed as condyle fracture in 23 patients under 15 years old age, They were treated with conservative method at Dental Hospital of Yonsei University from Jan., 1986 to Oct., 1994. Bony remodeling related with fracture pattern was evaluated. The results obtained are as follows: 1. The ratio of male to female in patients with condyle fracture was 1 : 0.9 and the difference of sex ratio was not noted. Comparing with preschool-age group and school-age group, age frequency was higher in preschool-age group (83%). 2. Fallen down (54%) was the most frequent cause of condyle fractures. Traffic accident and slip down were followed. 3. The most common clinical sign of condyle fractures was tenderness to palpation (19 cases). Mouth opening limitation (17 cases), swelling (7 cases), malocclusion (3 cases) were next in order. 4. According to sites of condyle fractures, unilateral fractures were in 20 patients and bilateral fractures in 3 patients, therefore total 23 patients-26 cases of condyle fracture were observed. According to fracture distribution, condyle fractures were in 10 patients (44%). Condyle fractures with symphysis fracture (9 patients, 39%), condyle fractures with ascending ramus fracture (2 patients, 9%), condyle fracture with mandibular body fracture (1 patient, 4%), and condyle fractures with mandibular angle fracture (1 patient, 4%) were followed. 5. In displacement pattern of fractured fragment of mandibular condyle, displacement (17 cases, 66%) was most common. Dislocation (5 cases, 19%) and deviation (4 cases, 15%) were next in order. 6. During the observation period of fractured condyles, remodeling patterns of fracture sites related with articular fossa were observed with usual congealer shape in 23

  14. A clinico-radiologic study of bony remodeling of the fractured condyles in children

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jeong Shin; Park, Chang Seo [Department of Dentistry, The Graduate School, Yonsei University, Seoul (Korea, Republic of)

    1995-08-15

    Bony remodeling pattern of condyle fractures in children are different from in adult for growing of condyle, also might affect treatment and prognosis of the condyle fracture. Subjects of this clinical and radiologic study were 26 temporomandibular joints diagnosed as condyle fracture in 23 patients under 15 years old age, They were treated with conservative method at Dental Hospital of Yonsei University from Jan., 1986 to Oct., 1994. Bony remodeling related with fracture pattern was evaluated. The results obtained are as follows: 1. The ratio of male to female in patients with condyle fracture was 1 : 0.9 and the difference of sex ratio was not noted. Comparing with preschool-age group and school-age group, age frequency was higher in preschool-age group (83%). 2. Fallen down (54%) was the most frequent cause of condyle fractures. Traffic accident and slip down were followed. 3. The most common clinical sign of condyle fractures was tenderness to palpation (19 cases). Mouth opening limitation (17 cases), swelling (7 cases), malocclusion (3 cases) were next in order. 4. According to sites of condyle fractures, unilateral fractures were in 20 patients and bilateral fractures in 3 patients, therefore total 23 patients-26 cases of condyle fracture were observed. According to fracture distribution, condyle fractures were in 10 patients (44%). Condyle fractures with symphysis fracture (9 patients, 39%), condyle fractures with ascending ramus fracture (2 patients, 9%), condyle fracture with mandibular body fracture (1 patient, 4%), and condyle fractures with mandibular angle fracture (1 patient, 4%) were followed. 5. In displacement pattern of fractured fragment of mandibular condyle, displacement (17 cases, 66%) was most common. Dislocation (5 cases, 19%) and deviation (4 cases, 15%) were next in order. 6. During the observation period of fractured condyles, remodeling patterns of fracture sites related with articular fossa were observed with usual congealer shape in 23

  15. MR imaging of growth plate injury in rabbit: development of bony bridge and pathologic correlation

    International Nuclear Information System (INIS)

    To evaluate the MR findings of a development of bony bridge within tunnels drilled across growth plates after injury in immature rabbits, and to correlate the MR and pathological findings. In 19 young rabbits, a growth-plate injury model was constructed in the distal femur by longitudinal drilling with a 5-mm drill. Coronal scans with T1-weighted, T2-weighted fast spin-echo, gradient echo, and gadolinium enhanced T1-weighted sequences were obtained immediately, and at 1, 2, 3, and 4 weeks, and 3, 6 months, postoperatively. Each group underwent pathologic examination, and the signal intensity, shape, and enhancement pattern of the drill holes were assessed. All results were correlated with pathologic findings. During the early period, the signal intensity of the defect site varied due to hemorrhage and inflammatory reaction in the lesion, becoming isointense to that of metaphyseal marrow on all sequences during the late period (3 and 6 months). Pathologically, it corresponded to replacement of the osseous bridge with fatty marrow. The new bone formation shown by pathologic examination to be present in the periphery of the defect during the first week corresponded to the vertical dark rim seen on MR images. It appeared during that week and became more distinct, thickening gradually until the fourth week. Enhancement was absent or faint on follow-up immediately after surgery, inhomogeneous and seen in half the rabbits at week 1, and maximal and homogenous at weeks 2 and 3. It had decreased by week 4, and was absent at months 3 and 6. These findings corresponded to the changes in transphyseal vascularity across the drill hole revealed by pathologic examination. The contrast enhancement demonstrated by defective growth plate may indicate the development of vascularity throughout the plate, a phenomenon which precedes the formation of a bony bridge after trauma. (author)

  16. Effect of heterogeneity and anisotropy related to the construction method on transfer processes in waste rock piles.

    Science.gov (United States)

    Lahmira, Belkacem; Lefebvre, René; Aubertin, Michel; Bussière, Bruno

    2016-01-01

    Waste rock piles producing acid mine drainage (AMD) are partially saturated systems involving multiphase (gas and liquid) flow and coupled transfer processes. Their internal structure and heterogeneous properties are inherited from their wide-ranging material grain sizes, their modes of deposition, and the underlying topography. This paper aims at assessing the effect of physical heterogeneity and anisotropy of waste rock piles on the physical processes involved in the generation of AMD. Generic waste rock pile conditions were represented with the numerical simulator TOUGH AMD based on those found at the Doyon mine waste rock pile (Canada). Models included four randomly distributed material types (coarse, intermediate, fine and very fine-grained). The term "randomly" as used in this study means that the vertical profile and spatial distribution of materials in waste rock piles (internal structure) defy stratigraphy principles applicable to natural sediments (superposition and continuity). The materials have different permeability and capillary properties, covering the typical range of materials found in waste rock piles. Anisotropy with a larger horizontal than vertical permeability was used to represent the effect of pile construction by benches, while the construction by end-dumping was presumed to induce a higher vertical than horizontal permeability. Results show that infiltrated precipitation preferentially flows in fine-grained materials, which remain almost saturated, whereas gas flows preferentially through the most permeable coarse materials, which have higher volumetric gas saturation. Anisotropy, which depends on pile construction methods, often controls global gas flow paths. Construction by benches favours lateral air entry close to the pile slope, whereas end-dumping leads to air entry from the surface to the interior of the pile by secondary gas convection cells. These results can be useful to construct and rehabilitate waste rock piles to minimize

  17. Effect of heterogeneity and anisotropy related to the construction method on transfer processes in waste rock piles

    Science.gov (United States)

    Lahmira, Belkacem; Lefebvre, René; Aubertin, Michel; Bussière, Bruno

    2016-01-01

    Waste rock piles producing acid mine drainage (AMD) are partially saturated systems involving multiphase (gas and liquid) flow and coupled transfer processes. Their internal structure and heterogeneous properties are inherited from their wide-ranging material grain sizes, their modes of deposition, and the underlying topography. This paper aims at assessing the effect of physical heterogeneity and anisotropy of waste rock piles on the physical processes involved in the generation of AMD. Generic waste rock pile conditions were represented with the numerical simulator TOUGH AMD based on those found at the Doyon mine waste rock pile (Canada). Models included four randomly distributed material types (coarse, intermediate, fine and very fine-grained). The term "randomly" as used in this study means that the vertical profile and spatial distribution of materials in waste rock piles (internal structure) defy stratigraphy principles applicable to natural sediments (superposition and continuity). The materials have different permeability and capillary properties, covering the typical range of materials found in waste rock piles. Anisotropy with a larger horizontal than vertical permeability was used to represent the effect of pile construction by benches, while the construction by end-dumping was presumed to induce a higher vertical than horizontal permeability. Results show that infiltrated precipitation preferentially flows in fine-grained materials, which remain almost saturated, whereas gas flows preferentially through the most permeable coarse materials, which have higher volumetric gas saturation. Anisotropy, which depends on pile construction methods, often controls global gas flow paths. Construction by benches favours lateral air entry close to the pile slope, whereas end-dumping leads to air entry from the surface to the interior of the pile by secondary gas convection cells. These results can be useful to construct and rehabilitate waste rock piles to minimize

  18. Overcoming Heterogeneity Effects Through Polymer-Enhanced Groundwater Remediation Techniques: Coupling Polymer Floods with Chemical Oxidants and Bio-agents

    Science.gov (United States)

    Smith, M. M.; Silva, J. A.; Munakata-Marr, J.; McCray, J. E.

    2008-12-01

    Even small heterogeneity contrasts in contaminated systems (resulting from differences in permeability or contaminant saturation) can affect the distribution of injected remediation agents by channeling fluids through high-permeability flowpaths, thus bypassing some regions and leaving contaminants uncontacted. The addition of a viscous polymer solution to the remediation agent may enhance agent delivery as a result of increased cross-flow (or "sweep efficiency") into different layers of the system, if the polymer solution remains stable in the presence of the remediation agent. Our research combines various non-toxic, food- grade polymer solutions with the remediation techniques of chemical oxidation and bio-remediation, to increase the effectiveness of treatment at sites contaminated with non-aqueous phase liquids (NAPLs). The coupling of polymer floods with oxidants may help to combat contaminant "rebound" sometimes associated with incomplete contaminant destruction in low-permeability zones. Initial compatibility testing has shown that certain robust polymer/oxidant mixtures possess stable viscosities and pose low additional oxidant demands over multi-day timescales. Transport of these solutions through natural porous media was studied in column experiments, and small two-dimensional experiments with heterogeneous layering were conducted to assess effectiveness of contaminant destruction. Limitations of these compatible polymer/oxidant combinations as well as possible experimental strategies to optimize delivery are also discussed. In addition, results of polymer/microbial screening tests reveal that polymer solutions do not inhibit the dechlorinating capabilities of a microbial consortium. Preliminary findings have also raised the possibility that certain polymers may successfully serve as electron donors in the subsurface. The implications of these results for either bioaugmentation or delivery of biostimulants are presented.

  19. Mitochondrial phylogenomics of early land plants: mitigating the effects of saturation, compositional heterogeneity, and codon-usage bias.

    Science.gov (United States)

    Liu, Yang; Cox, Cymon J; Wang, Wei; Goffinet, Bernard

    2014-11-01

    Phylogenetic analyses using concatenation of genomic-scale data have been seen as the panacea for resolving the incongruences among inferences from few or single genes. However, phylogenomics may also suffer from systematic errors, due to the, perhaps cumulative, effects of saturation, among-taxa compositional (GC content) heterogeneity, or codon-usage bias plaguing the individual nucleotide loci that are concatenated. Here, we provide an example of how these factors affect the inferences of the phylogeny of early land plants based on mitochondrial genomic data. Mitochondrial sequences evolve slowly in plants and hence are thought to be suitable for resolving deep relationships. We newly assembled mitochondrial genomes from 20 bryophytes, complemented these with 40 other streptophytes (land plants plus algal outgroups), compiling a data matrix of 60 taxa and 41 mitochondrial genes. Homogeneous analyses of the concatenated nucleotide data resolve mosses as sister-group to the remaining land plants. However, the corresponding translated amino acid data support the liverwort lineage in this position. Both results receive weak to moderate support in maximum-likelihood analyses, but strong support in Bayesian inferences. Tests of alternative hypotheses using either nucleotide or amino acid data provide implicit support for their respective optimal topologies, and clearly reject the hypotheses that bryophytes are monophyletic, liverworts and mosses share a unique common ancestor, or hornworts are sister to the remaining land plants. We determined that land plant lineages differ in their nucleotide composition, and in their usage of synonymous codon variants. Composition heterogeneous Bayesian analyses employing a nonstationary model that accounts for variation in among-lineage composition, and inferences from degenerated nucleotide data that avoid the effects of synonymous substitutions that underlie codon-usage bias, again recovered liverworts being sister to the

  20. Effect of spatial vegetation and relief heterogeneity on vertical CO2 fluxes between land surface and the atmosphere

    Science.gov (United States)

    Olchev, Alexander; Mukhartova, Yulia; Levashova, Natalia; Volkova, Elena

    2015-04-01

    The main goal of the study is to describe the influence of spatial vegetation and relief heterogeneity on turbulent CO2 fluxes between land surface and the atmosphere using a process-based two-dimensional turbulent exchange models. As a key area for this modeling study the hilly territory situated at the southern boundary of broadleaf forest community in European part of Russia (Tula region) was selected. The vegetation cover in the study region is mainly represented by mosaic of agricultural areas, grasslands, mires and groves that makes very difficult an adequate determining the local and regional CO2 fluxes using experimental methods only. Applied two two-dimensional models based on solution of the Navier-Stokes and continuity equations using the first-order and one-and-a-half order (TKE) closure schemes. Numerical scheme of the first-order closure model is based on the theory of contrast structures (Levashova et al 2005). For description of the plant canopy photosynthesis and respiration rates an aggregated approach based on the model of Ball et al (1987) in Leuning modification (1990, 1995), the Beer-Lambert equation for the description of solar radiation penetration within a plant canopy (Monsi, Saeki 1953), and also an algorithm describing the response of stomatal conductance of the leaves to incoming photosynthetically active radiation is used. All necessary input parameters describing the photosynthesis and respiration properties of different plants and soil types in the study region were obtained from the field measurements or taken from the literature. To quantify the possible effects of relief and vegetation heterogeneity on CO2 fluxes the three transects crossing the study area were chosen. For each transect the 2D patterns of wind speed components, turbulent exchange coefficients, CO2 concentrations and fluxes were calculated both for actual vegetation structure and for additional scenario assuming the total area deforestation. All modeling

  1. Class Size Effects on Student Achievement: Heterogeneity across Abilities and Fields

    Science.gov (United States)

    De Paola, Maria; Ponzo, Michela; Scoppa, Vincenzo

    2013-01-01

    In this paper, we analyze class size effects on college students exploiting data from a project offering special remedial courses in mathematics and language skills to freshmen enrolled at an Italian medium-sized public university. To estimate the effects of class size, we exploit the fact that students and teachers are virtually randomly assigned…

  2. Bound values for Hall conductivity of heterogeneous medium under quantum Hall effect conditions

    Indian Academy of Sciences (India)

    V E Arkhincheev

    2008-02-01

    Bound values for Hall conductivity under quantum Hall effect (QHE) conditions in inhomogeneous medium has been studied. It is shown that bound values for Hall conductivity differ from bound values for metallic conductivity. This is due to the unusual character of current percolation under quantum Hall effect conditions.

  3. Examining Heterogeneity in the Effect of Taking Algebra in Eighth Grade

    Science.gov (United States)

    Rickles, Jordan H.

    2013-01-01

    Increased access to algebra was a focal point of the National Mathematics Advisory Panel's 2008 report on improving mathematics learning in the United States. Past research found positive effects for early access to algebra, but the focus on average effects may mask important variation across student subgroups. The author addresses whether…

  4. Heterogeneity in rebound effects: Estimated results and impact of China’s fossil-fuel subsidies

    International Nuclear Information System (INIS)

    Highlights: • Rebound effects for China’s sectors are estimated. • The input–output model is a suitable model to analysis energy rebound effects across sectors. • The impacts of fossil-fuel subsidies on rebound effects are evaluated. • Technological progress has varies impactions on energy conservation, thereby rebound effects. - Abstract: Improving energy efficiency through technological advancement has become a primary measure to achieve energy conservation targets in China. However, the existence of energy rebound effects may completely or partially offset energy savings associated with technological advancement. From sectors perspective, technological advancement is not a necessary condition for energy conservation for a given sector because of varied rates of technological advancement and dependence among sectors. Adopting the input–output model, this article presents a detailed analysis of energy rebound effects in China’s economy at the aggregate and sectoral level over 2006–2010. The results show that the aggregate sectors’ rebound effect is about 11.31%, which is larger than without considering the interaction among sectors (11.25%); and strongly suggests that technological advancement has varied impacts on energy conservation and rebound effects. Thus various strategies of technological advancement and incorporated mitigation measures are necessary for energy conservation across sectors. Furthermore, the current study confirms that China’s total value of fossil-fuel subsidies reached 160.23 billion US$ (constant 2005 price) in 2006–2010; and after removal of subsidies, the energy use is expected to save 411.35 million toe and the rebound effects for aggregate sectors become 10.64%. Finally, some relevant policy issues are discussed in depth

  5. Study the effect of reservoir spatial heterogeneity on CO2 sequestration under an uncertainty quantification (UQ) software framework

    Science.gov (United States)

    Fang, Y.; Hou, J.; Engel, D.; Lin, G.; Yin, J.; Han, B.; Fang, Z.; Fountoulakis, V.

    2011-12-01

    In this study, we introduce an uncertainty quantification (UQ) software framework for carbon sequestration, with the focus of studying being the effect of spatial heterogeneity of reservoir properties on CO2 migration. We use a sequential Gaussian method (SGSIM) to generate realizations of permeability fields with various spatial statistical attributes. To deal with the computational difficulties, we integrate the following ideas/approaches: 1) firstly, we use three different sampling approaches (probabilistic collocation, quasi-Monte Carlo, and adaptive sampling approaches) to reduce the required forward calculations while trying to explore the parameter space and quantify the input uncertainty; 2) secondly, we use eSTOMP as the forward modeling simulator. eSTOMP is implemented using the Global Arrays toolkit (GA) that is based on one-sided inter-processor communication and supports a shared memory programming style on distributed memory platforms. It provides highly-scalable performance. It uses a data model to partition most of the large scale data structures into a relatively small number of distinct classes. The lower level simulator infrastructure (e.g. meshing support, associated data structures, and data mapping to processors) is separated from the higher level physics and chemistry algorithmic routines using a grid component interface; and 3) besides the faster model and more efficient algorithms to speed up the forward calculation, we built an adaptive system infrastructure to select the best possible data transfer mechanisms, to optimally allocate system resources to improve performance, and to integrate software packages and data for composing carbon sequestration simulation, computation, analysis, estimation and visualization. We will demonstrate the framework with a given CO2 injection scenario in a heterogeneous sandstone reservoir.

  6. Heterogeneous road networks have no apparent effect on the genetic structure of small mammal populations.

    Science.gov (United States)

    Grilo, Clara; Del Cerro, Irene; Centeno-Cuadros, Alejandro; Ramiro, Victor; Román, Jacinto; Molina-Vacas, Guillem; Fernández-Aguilar, Xavier; Rodríguez, Juan; Porto-Peter, Flávia; Fonseca, Carlos; Revilla, Eloy; Godoy, José A

    2016-09-15

    Roads are widely recognized to represent a barrier to individual movements and, conversely, verges can act as potential corridors for the dispersal of many small mammals. Both barrier and corridor effects should generate a clear spatial pattern in genetic structure. Nevertheless, the effect of roads on the genetic structure of small mammal populations still remains unclear. In this study, we examine the barrier effect that different road types (4-lane highway, 2-lane roads and single-lane unpaved roads) may have on the population genetic structure of three species differing in relevant life history traits: southern water vole Arvicola sapidus, the Mediterranean pine vole Microtus duodecimcostatus and the Algerian mouse Mus spretus. We also examine the corridor effect of highway verges on the Mediterranean pine vole and the Algerian mouse. We analysed the population structure through pairwise estimates of FST among subpopulations bisected by roads, identified genetic clusters through Bayesian assignment approaches, and used simple and partial Mantel tests to evaluate the relative barrier or corridor effect of roads. No strong evidences were found for an effect of roads on population structure of these three species. The barrier effect of roads seems to be site-specific and no corridor effect of verges was found for the pine vole and Algerian mouse populations. The lack of consistent results among species and for each road type lead us to believe that the ability of individual dispersers to use those crossing structures or the habitat quality in the highway verges may have a relatively higher influence on gene flow among populations than the presence of crossing structures per se. Further research should include microhabitat analysis and the estimates of species abundance to understand the mechanisms that underlie the genetic structure observed at some sites. PMID:27219505

  7. Does bony hip morphology affect the outcome of treatment for patients with adductor-related groin pain?

    DEFF Research Database (Denmark)

    Hölmich, Per; Thorborg, Kristian; Nyvold, Per;

    2014-01-01

    BACKGROUND: Adductor-related groin pain and bony morphology such as femoroacetabular impingement (FAI) or hip dysplasia can coexist clinically. A previous randomised controlled trial in which athletes with adductor-related groin pain underwent either passive treatment (PT) or active treatment (AT...

  8. Fractionation in normal tissues: the (α/β)eff concept can account for dose heterogeneity and volume effects

    International Nuclear Information System (INIS)

    The simple Linear–Quadratic (LQ)-based Withers iso-effect formula (WIF) is widely used in external-beam radiotherapy to derive a new tumour dose prescription such that there is normal-tissue (NT) iso-effect when changing the fraction size and/or number. However, as conventionally applied, the WIF is invalid unless the normal-tissue response is solely determined by the tumour dose. We propose a generalized WIF (gWIF) which retains the tumour prescription dose, but replaces the intrinsic fractionation sensitivity measure (α/β) by a new concept, the normal-tissue effective fractionation sensitivity, (α/β)effNT, which takes into account both the dose heterogeneity in, and the volume effect of, the late-responding normal-tissue in question. Closed-form analytical expressions for (α/β)effNT ensuring exact normal-tissue iso-effect are derived for: (i) uniform dose, and (ii) arbitrary dose distributions with volume-effect parameter n = 1 from the normal-tissue dose–volume histogram. For arbitrary dose distributions and arbitrary n, a numerical solution for (α/β)effNT exhibits a weak dependence on the number of fractions. As n is increased, (α/β)effNT increases from its intrinsic value at n = 0 (100% serial normal-tissue) to values close to or even exceeding the tumour (α/β) at n = 1 (100% parallel normal-tissue), with the highest values of (α/β)effNT corresponding to the most conformal dose distributions. Applications of this new concept to inverse planning and to highly conformal modalities are discussed, as is the effect of possible deviations from LQ behaviour at large fraction sizes. (paper)

  9. Fractionation in normal tissues: the (α/β)eff concept can account for dose heterogeneity and volume effects

    Science.gov (United States)

    Hoffmann, Aswin L.; Nahum, Alan E.

    2013-10-01

    The simple Linear-Quadratic (LQ)-based Withers iso-effect formula (WIF) is widely used in external-beam radiotherapy to derive a new tumour dose prescription such that there is normal-tissue (NT) iso-effect when changing the fraction size and/or number. However, as conventionally applied, the WIF is invalid unless the normal-tissue response is solely determined by the tumour dose. We propose a generalized WIF (gWIF) which retains the tumour prescription dose, but replaces the intrinsic fractionation sensitivity measure (α/β) by a new concept, the normal-tissue effective fractionation sensitivity, (\\alpha /\\beta )_{eff}^{NT}, which takes into account both the dose heterogeneity in, and the volume effect of, the late-responding normal-tissue in question. Closed-form analytical expressions for (\\alpha /\\beta )_{eff}^{NT} ensuring exact normal-tissue iso-effect are derived for: (i) uniform dose, and (ii) arbitrary dose distributions with volume-effect parameter n = 1 from the normal-tissue dose-volume histogram. For arbitrary dose distributions and arbitrary n, a numerical solution for (\\alpha /\\beta )_{eff}^{NT} exhibits a weak dependence on the number of fractions. As n is increased, (\\alpha /\\beta )_{eff}^{NT} increases from its intrinsic value at n = 0 (100% serial normal-tissue) to values close to or even exceeding the tumour (α/β) at n = 1 (100% parallel normal-tissue), with the highest values of (\\alpha /\\beta )_{eff}^{NT} corresponding to the most conformal dose distributions. Applications of this new concept to inverse planning and to highly conformal modalities are discussed, as is the effect of possible deviations from LQ behaviour at large fraction sizes.

  10. Fractionation in normal tissues: the (α/β)eff concept can account for dose heterogeneity and volume effects.

    Science.gov (United States)

    Hoffmann, Aswin L; Nahum, Alan E

    2013-10-01

    The simple Linear-Quadratic (LQ)-based Withers iso-effect formula (WIF) is widely used in external-beam radiotherapy to derive a new tumour dose prescription such that there is normal-tissue (NT) iso-effect when changing the fraction size and/or number. However, as conventionally applied, the WIF is invalid unless the normal-tissue response is solely determined by the tumour dose. We propose a generalized WIF (gWIF) which retains the tumour prescription dose, but replaces the intrinsic fractionation sensitivity measure (α/β) by a new concept, the normal-tissue effective fractionation sensitivity, [Formula: see text], which takes into account both the dose heterogeneity in, and the volume effect of, the late-responding normal-tissue in question. Closed-form analytical expressions for [Formula: see text] ensuring exact normal-tissue iso-effect are derived for: (i) uniform dose, and (ii) arbitrary dose distributions with volume-effect parameter n = 1 from the normal-tissue dose-volume histogram. For arbitrary dose distributions and arbitrary n, a numerical solution for [Formula: see text] exhibits a weak dependence on the number of fractions. As n is increased, [Formula: see text] increases from its intrinsic value at n = 0 (100% serial normal-tissue) to values close to or even exceeding the tumour (α/β) at n = 1 (100% parallel normal-tissue), with the highest values of [Formula: see text] corresponding to the most conformal dose distributions. Applications of this new concept to inverse planning and to highly conformal modalities are discussed, as is the effect of possible deviations from LQ behaviour at large fraction sizes. PMID:24029492

  11. Quantitative computed tomography as a test of endurance for evaluation of bony plates; Utilizacao da tomografia computadorizada quantitativa como teste de resistencia para avaliacao de placas osseas

    Energy Technology Data Exchange (ETDEWEB)

    Melo Filho, E.V.; Costa, L.A.V.S.; Oliveira, D.C. [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil); Freitas, P.M.C. [Escola de Veterinaria - Universidade Federal de Minas Gerais - Belo Horizonte, MG (Brazil); Teixeira, M.W.; Costa, F.S. [Universidade Federal Rural de Pernambuco - Recife, PE (Brazil)

    2012-06-15

    Quantitative computed tomography was used to determine the radiodensity of bony plates. The CT scans provided information regarding radiodensity of bony plates and allowed to verify the uniformity of bone mineral density in their scope. The proposed methodology should be considered as another tool for determining the resistance of these biomaterials. (author)

  12. Bony fragments in the tarsocrural and metacarpo- or metatarsophalangeal joints in the Standardbred horse - a radiographic survey

    International Nuclear Information System (INIS)

    Radiographic examination of the tarsocrural, metacarpo- or metatarsophalangeal joints was made in 139 Standardbred horses. Most were under three years old with no history of orthopaedic problems. In the tarsocrural joint, osteochondrosis was observed in 25 (18.1 percent) of the horses (n = 138) and 14 (56 percent) of these were affected bilaterally. In the metatarsophalangeal joint, the most frequent radiographic abnormality was single or multiple bony fragments or defects at the plantar proximal end of the proximal phalanx, which was noticed in 40 (28.8 percent) of the horses (n = 139). The lesion was much more frequent in the hind than in the forelimbs. Ten percent of horses affected in the hindlimbs had the lesions bilaterally. Palmar or plantar fragments wee also more common in the medial, than the lateral, part of the joint. With regard to osteochondrosis in the tarsocrural joint and palmar or plantar bony fragments in the metacarpo- or metatarsophalangeal joints, no significant differences in incidence were found between sexes or between left and right sides. There was no correlation between findings of osteochondrosis in the tarsocrural joints and the occurrence of bony fragments in the plantar part of the metatarsophalangeal joints. In the forelimbs, bony fragments in the dorsal parts of the metacarpophalangeal joint were noticed in three (2.9 percent) of the horse (n = 103) and the corresponding figure for the metatarsophalangeal joint was three (2.2 percent) (n = 139). In 102 horses, the tarsocrural, the metacarpo- and the metatarsophalangeal joints were radiographed at the same time. One or several joints were affected with osteochondrosis, bony fragments, or defects in underlying bones in 45 (44.1 percent) of these horses. (author)

  13. Three-dimensional heterogenous fields in metallic multicrystals with explicit account of grain boundary effects

    International Nuclear Information System (INIS)

    Full text: A significant portion of modern material technology is concerned with materials that possess a polycrystalline structure, i.e. a collection of grains with different lattice orientations. A direct consequence of the periodic structure of the lattice is the anisotropic behavior of the single crystal and, therefore, the resulting dependence of the polycrystal properties on grain orientation, shape and distribution (texture). The resulting macroscopic properties of the material including its anisotropy are ultimately dictated by the resulting texture and other microstructural effects. A number of basic strategies have been proposed to describe the aggregate behavior of the crystallites. These theories postulate some mean-field hypothesis on the response of a collection of grain orientations associated with a continuum material point and result in some averaging procedure of the response of the single crystals. In this paper we present the evolution of the inhomogeneous features of the full 3D stress and strain fields in metallic polycrystals arising from the lattice misorientation among grains and grain boundary effects. The computation of full field solutions is especially critical for the analysis of the deformation of crystals with low symmetry. In these materials, inhomogeneity of deformation stems from an increased grain constraint effect. Effective calculations of these systems require massive parallel computation, which is accomplished by partitioning the finite element mesh so as to equidistribute the number of elements among the processors while minimizing communications. Each mesh partition is assigned to a different processor and the grains are identified with the mesh partitions. Refs. 7 (author)

  14. Interval Estimates of Multivariate Effect Sizes: Coverage and Interval Width Estimates under Variance Heterogeneity and Nonnormality

    Science.gov (United States)

    Hess, Melinda R.; Hogarty, Kristine Y.; Ferron, John M.; Kromrey, Jeffrey D.

    2007-01-01

    Monte Carlo methods were used to examine techniques for constructing confidence intervals around multivariate effect sizes. Using interval inversion and bootstrapping methods, confidence intervals were constructed around the standard estimate of Mahalanobis distance (D[superscript 2]), two bias-adjusted estimates of D[superscript 2], and Huberty's…

  15. Elevational pattern of species richness in the Three Gorges region of the Yangtze River: effect of climate, geometric constraints, area and topographical heterogeneity

    Directory of Open Access Journals (Sweden)

    Qiaoyan Li

    2013-03-01

    Full Text Available In this paper, we explore altitudinal richness of vascular plant species in the Three Gorges region of the Yangtze River and test several hypotheses concerning geographic diversity patterns. Multivariate regression and variation partitioning analyses were used to examine the relative effects of area, climate, geometric constraints and topographical heterogeneity on altitudinal richness patterns, and also the differences among ecological groups (including species with different range sizes, growth forms and biogeographic affinities. Our results show that, water–energy dynamics have the strongest total effect (>93% in explaining richness patterns for various species groups. However, for many species groups the effects of water–energy dynamics were largely shared with geometric constraints, topographical heterogeneity or area. Geometric constraints had strong effects on species with large ranges, but negligible effects on small-ranged species. Area showed relative strong correlation with species richness, but was excluded from multivariate models for most species groups, when other potential mechanisms were considered simultaneously. On the contrary, topographic heterogeneity showed weak correlation with richness patterns but was included in most of the final multivariate models. We concluded that water–energy dynamics were most important in explaining altitudinal richness patterns within the study region, while geometric constraints were important for species with large ranges. Topographic heterogeneity showed a weak but essential role in shaping altitudinal richness gradients, while the role of area on richness patterns requires further investigation because of the collinear relationships between area, geometric constraints and climatic gradients.

  16. Effects of various poisoning compounds on the activity and stereospecificity of heterogeneous Ziegler–Natta catalyst

    OpenAIRE

    Kitti Tangjituabun et al

    2008-01-01

    A TiCl4/ethylbenzoate/MgCl2 Ziegler–Natta catalyst was pretreated with chemically different poisoning compounds to investigate their effects on the catalyst activity and stereospecificity for propylene polymerization. The poisoning power on the activity was in the order of methanol > acetone > ethyl acetate. A kinetic analysis using the stopped-flow method revealed that addition of the poisoning materials decreased the activity through the reduction of the number of active sites, whereas the ...

  17. Autosomal dominant ataxia: Genetic evidence for locus heterogeneity from a cuban founder-effect population

    OpenAIRE

    Auburger, Georg; Diaz, Guillermo Orozco; Capote, Raul Ferreira; Sanchez, Suzana Gispert; Perez, Marta Paradoa; del Cueto, Marianela Estrada; Meneses, Mirna Garcia; Farrall, Martin; Williamson, Robert; Chamberlain, Susan; Baute, Luis Heredero

    1990-01-01

    The locus for autosomal dominant ataxia with a diagnosis of olivo-ponto-cerebellar atrophy at autopsy has been previously assigned to chromosome 6p. However, evidence for two alternative locations has been reported. We have recently described a large potential founder-effect population of such patients in the Holguin province of Cuba. With an estimated 1,000 patients available for analysis, this extensive cluster of families provides a unique opportunity for the definitive localization of the...

  18. Sedimentological Correlation of Heterogeneous Reservoir Rocks: Effects of Lithology, Differential Compaction and Diagenetic Processes

    OpenAIRE

    Hammer, Erik

    2010-01-01

    Correlation of reservoir rocks is a challenge in many types of reservoirs around the world today. In a time where the focus has slowly shifted away from the giant fields, towards development of smaller, more marginal fields, the importance of addressing these challenges is increasing. The purpose of the thesis is to investigate the effects of lithology, diagenesis and differential compaction on correlation of reservoir architecture in a fluviodeltaic reservoir. To be able to address these iss...

  19. Poverty dynamics in Nairobi's slums: testing for true state dependence and heterogeneity effects

    OpenAIRE

    Faye, Ousmane; Islam, Nizamul; Zulu, Eliya

    2011-01-01

    We investigate the factors underlying poverty transitions in Nairobi?s slums focusing on whether differences in characteristics make some individuals more prone to enter poverty and persist in, or whether past experience of poverty matters on future poverty situations. Answers to these issues are crucial for designing effective and successful poverty alleviation policies in informal residential settlements in Africa. The paper uses an endogenous switching model, which accounts for initial con...

  20. Genetics of susceptibility to leishmaniasis in mice: four novel loci and functional heterogeneity of gene effects

    Czech Academy of Sciences Publication Activity Database

    Havelková, Helena; Badalová, Jana; Svobodová, M.; Vojtíšková, Jarmila; Kurey, Irina; Vladimirov, Vladimir; Demant, P.; Lipoldová, Marie

    2006-01-01

    Roč. 7, č. 3 (2006), s. 220-233. ISSN 1466-4879 R&D Projects: GA ČR(CZ) GA310/03/1381; GA ČR(CZ) GD310/03/H147 Grant ostatní: HHMI(US) 55000323 Institutional research plan: CEZ:AV0Z50520514 Keywords : leishmaniasis * host response * gene effect Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.533, year: 2006

  1. Analyzing Zero Returns to Education in Germany: Heterogeneous Effects and Skill Formation

    OpenAIRE

    Kamhöfer, Daniel A.; Schmitz, Hendrik

    2013-01-01

    We analyze the causal effect of education on old-age cognitive abilities using German Socio-Economic Panel (SOEP) data and regional variation in mandatory years of schooling and the supply of schools. Our outcome variable is the score an individual reaches in an ultra-short intelligence test. We explain this score, using instrumented education. Instrumental variable estimation is necessary since on the one hand, schooling is highly affected by cognitive skills (reverse causality), and, on the...

  2. Heterogeneous nucleation of hydroxyapatite on protein: structural effect of silk sericin

    OpenAIRE

    Takeuchi, Akari; Ohtsuki, Chikara; Miyazaki, Toshiki; Kamitakahara, Masanobu; Ogata, Shin-ichi; Yamazaki, Masao; Furutani, Yoshiaki; Kinoshita, Hisao; Tanihara, Masao

    2005-01-01

    Acidic proteins play an important role during mineral formation in biological systems, but the mechanism of mineral formation is far from understood. In this paper, we report on the relationship between the structure of a protein and hydroxyapatite deposition under biomimetic conditions. Sericin, a type of silk protein, was adopted as a suitable protein for studying structural effect on hydroxyapatite deposition, since it forms a hydroxyapatite layer on its surface in a metastable calcium pho...

  3. CO2 storage in heterogeneous aquifer: A study on the effect of injection rate and CaCO3 concentration

    Science.gov (United States)

    Raza, A.; Rezaee, R.; Bing, C. H.; Gholami, R.; Nagarajan, R.; Hamid, M. A.

    2016-03-01

    Trapping mechanisms taken place during and after CO2 injection in a geologic storage medium are impacted by a number of parameters including injection rates together with rock and pore fluid compositions. There have been many studies on the factors controlling the capillary trapping and injectivity of CO2 storage sites. However, there are only few works carried out discussing on the effect of flow rate and rock and fluids compositions in controlling the trapping mechanisms. In this paper a CO2 storage site located in a heterogeneous aquifer is simulated to investigate the efficiency of structural, capillary and dissolution trappings as a function of injection rate and concentration of calcium carbonate. The results obtained from numerical analysis indicated that CO2 injection must be made within an optimum injection rate for having an effective storage in place. It was also found that concentration of CaCO3 is an important parameter to consider during the analysis as it drastically controls the fate of trapping mechanisms at high injection rates.

  4. Effects of various poisoning compounds on the activity and stereospecificity of heterogeneous Ziegler–Natta catalyst

    Directory of Open Access Journals (Sweden)

    Kitti Tangjituabun et al

    2008-01-01

    Full Text Available A TiCl4/ethylbenzoate/MgCl2 Ziegler–Natta catalyst was pretreated with chemically different poisoning compounds to investigate their effects on the catalyst activity and stereospecificity for propylene polymerization. The poisoning power on the activity was in the order of methanol > acetone > ethyl acetate. A kinetic analysis using the stopped-flow method revealed that addition of the poisoning materials decreased the activity through the reduction of the number of active sites, whereas the catalyst isospecificity was hardly affected by these materials.

  5. Effects of various poisoning compounds on the activity and stereospecificity of heterogeneous Ziegler-Natta catalyst

    Science.gov (United States)

    Tangjituabun, Kitti; Kim, Sang Yull; Hiraoka, Yuichi; Taniike, Toshiaki; Terano, Minoru; Jongsomjit, Bunjerd; Praserthdam, Piyasan

    2008-04-01

    A TiCl4/ethylbenzoate/MgCl2 Ziegler-Natta catalyst was pretreated with chemically different poisoning compounds to investigate their effects on the catalyst activity and stereospecificity for propylene polymerization. The poisoning power on the activity was in the order of methanol > acetone > ethyl acetate. A kinetic analysis using the stopped-flow method revealed that addition of the poisoning materials decreased the activity through the reduction of the number of active sites, whereas the catalyst isospecificity was hardly affected by these materials.

  6. Effect of mechanical stress on the kinetics of heterogeneous electron transfer.

    Science.gov (United States)

    Sun, Peng; Liu, Zhen; Yu, Honghui; Mirkin, Michael V

    2008-09-16

    The scanning electrochemical microscope (SECM) combined with a computerized tensile stage was employed to measure the kinetics of electron transfer (ET) reactions at stainless steel electrodes as a function of the applied mechanical stress. Reproducible current versus distance curves were obtained for different values of the tensile stress applied to a stainless steel (T-316) sample by using hexaammineruthenium as a redox mediator. The dependences of the extracted rate constant on substrate potential (i.e., Tafel plots, ln k versus E) were linear, in agreement with classical electrochemical theory. Possible origins of the stress effect on the ET rate and its implications for studies of stress corrosion cracking are discussed. PMID:18715024

  7. Effects of various poisoning compounds on the activity and stereospecificity of heterogeneous Ziegler-Natta catalyst

    International Nuclear Information System (INIS)

    A TiCl4/ethylbenzoate/MgCl2 Ziegler-Natta catalyst was pretreated with chemically different poisoning compounds to investigate their effects on the catalyst activity and stereospecificity for propylene polymerization. The poisoning power on the activity was in the order of methanol > acetone > ethyl acetate. A kinetic analysis using the stopped-flow method revealed that addition of the poisoning materials decreased the activity through the reduction of the number of active sites, whereas the catalyst isospecificity was hardly affected by these materials.

  8. Understanding Treatment Effects Heterogeneities Using Multi-Site Regression Discontinuity Designs: Example from a "Double-Dose" Algebra Study in Chicago

    Science.gov (United States)

    Nomi, Takako; Raudenbush, Stephen W.

    2012-01-01

    To understand heterogeneity in the effects of double-dose algebra across schools, the authors focus on two policy implementation features and their variation across schools. The first source of variation is the degree to which schools followed the cutoff-based course assignment policy. The second source of variation is the degree to which schools…

  9. Effective Hydraulic Conductivity Scaling in a 2-Dimensional Geometrical Multifractal Model for Aquifer Heterogeneity

    Science.gov (United States)

    Gentry, R. W.; Perfect, E.; Sukop, M. C.

    2005-12-01

    Recent analyses of field data suggest that the spatial variation of hydraulic conductivity, K, within an aquifer may be multifractal. We investigated the implications of this finding for the scaling of effective hydraulic conductivity, , by performing numerical simulations of flow in 2-dimensional geometrical multifractal K fields. A theoretical framework for generating such fields is presented based on the parameters of the truncated binomial distribution, TBD. This leads to an approximate analytical expression showing that increases with increasing length scale as a power law, whose exponent, α, is determined by the TBD parameters. Five geometrical multifractal K fields were generated with different minimum length scales. Each domain was discretized using a block center grid consisting of 59,049 uniformly-spaced nodes. A unit cube aquifer was used for the numerical simulations. The boundary conditions were implemented with constant head (unit gradient) parallel planes, and corresponding zero flux planes on the normal axes. A finite difference simulation model based on MODFLOW 2000 was used, and "zone budget" was employed to calculate the flow balance. The discharge into and out of the unit cube was then used to calculate based on Darcy's law. The numerical simulations produced similar increases in with increasing length scale to those predicted by the analytical model. Nonlinear regression analyses yielded estimates of α from the numerical simulations that were within 10% of the analytical value for these fields. These simulations provide a theoretical explanation for effective hydraulic conductivity scaling in terms of multifractals. The advantage of such an approach is that the α-parameter, which controls the degree of scaling, is physically-based and can potentially be estimated from independent measurements.

  10. Estimating the effects of detection heterogeneity and overdispersion on trends estimated from avian point counts.

    Science.gov (United States)

    Etterson, Matthew A; Niemi, Gerald J; Danz, Nicholas P

    2009-12-01

    Point counts are a common method for sampling avian distribution and abundance. Although methods for estimating detection probabilities are available, many analyses use raw counts and do not correct for detectability. We use a removal model of detection within an N-mixture approach to estimate abundance trends corrected for imperfect detection. We compare the corrected trend estimates to those estimated from raw counts for 16 species using 15 years of monitoring data on three national forests in the western Great Lakes, USA. We also tested the effects of overdispersion by modeling both counts and removal mixtures under three statistical distributions: Poisson, zero-inflated Poisson, and negative binomial. For most species, the removal model produced estimates of detection probability that conformed to expectations. For many species, but not all, estimates of trends were similar regardless of statistical distribution or method of analysis. Within a given combination of likelihood (counts vs. mixtures) and statistical distribution, trends usually differed by both stand type and national forest, with species showing declines in some stand types and increases in others. For three species, Brown Creeper, Yellow-rumped Warbler, and Black-throated Green Warbler, temporal patterns in detectability resulted in substantial differences in estimated trends under the removal mixtures compared to the analysis of raw counts. Overall, we found that the zero-inflated Poisson was the best distribution for our data, although the Poisson or negative binomial performed better for a few species. The similarity in estimated trends that we observed among counts and removal mixtures was probably a result of both experimental design and sampling effort. First, the study was originally designed to avoid confounding observer effects with habitats or time. Second, our time series is relatively long and our sample sizes within years are large. PMID:20014578

  11. Primary bony non-Hodgkin lymphoma of the cervical spine: a case report

    Directory of Open Access Journals (Sweden)

    Sedrak Mark F

    2010-02-01

    Full Text Available Abstract Introduction Non-Hodgkin lymphoma primarily originating from the bone is exceedingly rare. To our knowledge, this is the first report of primary bone lymphoma presenting with progressive cord compression from an origin in the cervical spine. Herein, we discuss the unusual location in this case, the presenting symptoms, and the management of this disease. Case presentation We report on a 23-year-old Caucasian-American man who presented with two months of night sweats, fatigue, parasthesias, and progressive weakness that had progressed to near quadriplegia. Magnetic resonance (MR imaging demonstrated significant cord compression seen primarily at C7. Surgical management, with corpectomy and dorsal segmental fusion, in combination with adjuvant chemotherapy and radiation therapy, halted the progression of the primary disease and preserved neurological function. Histological analysis demonstrated an aggressive anaplastic large cell lymphoma. Conclusion Isolated primary bony lymphoma of the spine is exceedingly rare. As in our case, the initial symptoms may be the result of progressive cervical cord compression. Anterior corpectomy with posterolateral decompression and fusion succeeded in preventing progressive neurologic decline and maintaining quality of life. The reader should be aware of the unique presentation of this disease and that surgical management is a successful treatment strategy.

  12. Automated bony region identification using artificial neural networks: reliability and validation measurements

    International Nuclear Information System (INIS)

    The objective was to develop tools for automating the identification of bony structures, to assess the reliability of this technique against manual raters, and to validate the resulting regions of interest against physical surface scans obtained from the same specimen. Artificial intelligence-based algorithms have been used for image segmentation, specifically artificial neural networks (ANNs). For this study, an ANN was created and trained to identify the phalanges of the human hand. The relative overlap between the ANN and a manual tracer was 0.87, 0.82, and 0.76, for the proximal, middle, and distal index phalanx bones respectively. Compared with the physical surface scans, the ANN-generated surface representations differed on average by 0.35 mm, 0.29 mm, and 0.40 mm for the proximal, middle, and distal phalanges respectively. Furthermore, the ANN proved to segment the structures in less than one-tenth of the time required by a manual rater. The ANN has proven to be a reliable and valid means of segmenting the phalanx bones from CT images. Employing automated methods such as the ANN for segmentation, eliminates the likelihood of rater drift and inter-rater variability. Automated methods also decrease the amount of time and manual effort required to extract the data of interest, thereby making the feasibility of patient-specific modeling a reality. (orig.)

  13. Radiotherapy for bony manifestations of Langerhans Cell Histiocytosis. Review and proposal for an international registry

    International Nuclear Information System (INIS)

    Purpose: to examine the role of radiotherapy (RT) in adult Langerhans Cell Histiocytosis (LCH) for osseous manifestations, to define open questions regarding RT, and to develop recommendations for the clinical decision-making and problem-solving process. Material and methods: a literature review using different medical databases was conducted including the last 3 decades, and resulting questions regarding the use of ionizing radiation were systematically compiled. Results: the literature review revealed a local control rate of 96% (93% complete remissions) in patients with osseous single-system disease and of 92% (76% complete remissions) in patients with bony involvement in multi-system disease. To increase our knowledge, a prospective registry has been developed to allow a differentiated analysis of RT outcome and definition of potential prognostic factors. Conclusion: ionizing radiation can be successfully applied as a single treatment or in combination with other therapies for osseous manifestations of LCH. It leads to high remission and local control rates. Nevertheless, many open questions still exist. A prospective clinical registry is proposed to define the exact role of RT in this disease and to develop future interdisciplinary treatment guidelines. (orig.)

  14. Radiotherapy for bony manifestations of Langerhans Cell Histiocytosis. Review and proposal for an international registry

    Energy Technology Data Exchange (ETDEWEB)

    Olschewski, T.; Seegenschmiedt, M.H. [Dept. of Radiotherapy and Radiation Oncology, Alfried Krupp Krankenhaus, Essen (Germany)

    2006-02-01

    Purpose: to examine the role of radiotherapy (RT) in adult Langerhans Cell Histiocytosis (LCH) for osseous manifestations, to define open questions regarding RT, and to develop recommendations for the clinical decision-making and problem-solving process. Material and methods: a literature review using different medical databases was conducted including the last 3 decades, and resulting questions regarding the use of ionizing radiation were systematically compiled. Results: the literature review revealed a local control rate of 96% (93% complete remissions) in patients with osseous single-system disease and of 92% (76% complete remissions) in patients with bony involvement in multi-system disease. To increase our knowledge, a prospective registry has been developed to allow a differentiated analysis of RT outcome and definition of potential prognostic factors. Conclusion: ionizing radiation can be successfully applied as a single treatment or in combination with other therapies for osseous manifestations of LCH. It leads to high remission and local control rates. Nevertheless, many open questions still exist. A prospective clinical registry is proposed to define the exact role of RT in this disease and to develop future interdisciplinary treatment guidelines. (orig.)

  15. Orbital Tumors Excision without Bony Marginotomy under Local and General Anesthesia

    Directory of Open Access Journals (Sweden)

    Robert A. Goldberg

    2014-01-01

    Full Text Available To present our experience of removing middle to deep orbital tumors using a combination of minimally invasive soft tissue approaches, sometimes under local anesthesia. Methods. In this retrospective case series, 30 patients (13 males and 17 females underwent tumor removal through eyelid crease (17 eyes, conjunctival (nine eyes, lateral canthal (two eyes, and transcaruncular (two eyes approaches. All tumors were located in the posterior half of the orbit. Six cases were removed under monitored anesthesia care with local block, and 24 were under general anesthesia. Results. The median (range age and follow-up duration were 48.5 (31–87 years old and 24.5 (4–375 weeks, respectively. Visual acuity and ocular motility showed improvement or no significant change in all but one patient at the latest followup. Confirmed pathologies revealed cavernous hemangioma (15 cases, pleomorphic adenoma (5 cases, solitary fibrous tumor (4 cases, neurofibroma (2 cases, schwannoma (2 cases, and orbital varix (1 case. None of the patients experienced recurrence. Conclusions. Creating a bony marginotomy increases intraoperative exposure of the deep orbit but adds substantial time and morbidity. Benign orbital tumors can often be removed safely through small soft-tissue incisions, without bone removal and under local anesthesia.

  16. Effect of Particle-Scale Heterogeneity on Uranium(VI) Transport in Unsaturated Porous Media

    International Nuclear Information System (INIS)

    Uranium (VI) sorption and transport was evaluated in mixtures of silt loam and coarse sand sediments using traditional static batch sorption, saturated column, and unsaturated centrifugation experiments to evaluate the association of mobile and immobile water domains with particles of different size and surface reactivity. Exclusion of conservative tracers and a decrease in uranium sorption compared to what was predicted by the Kd-mass-avg value observed in sediment mixtures where the mass fraction of silt loam was 10%. This is consistent with behavior that was previously reported for coarse and fine sand separates. No exclusion of the conservative tracer, as predicted for the moderate water content range, was measured during unsaturated transport in sediment mixtures that contained 30% or more silt loam by mass. However, sorption was greater than predicted based on the Kd-mass-avg value, which suggests the fine-textured silt was in contact with the mobile water domain. This is the first evidence linking sorption to transport in a particular water domain. Results of this investigation demonstrate the interaction between the geochemical and hydrodynamic processes has a profound effect on transport in unsaturated sediments. In particular, analyses of the data from the experiments on sediment mixtures illustrate how the hydrodynamic conditions have a significant impact on the breakthrough of sorptive solutes. Definition of the fraction of mobile water was especially important for defining the front of the BTC, which is integral to predicting the arrival time of solutes at a particular depth/location in the sediment

  17. Atrial natriuretic peptide receptor heterogeneity and effects on cyclic GMP accumulation

    International Nuclear Information System (INIS)

    The effects of atrial natriuretic peptide (ANP), oxytocin (OT) and vasopressin (AVP) on guanylate cyclase activity and cyclic GMP accumulation were examined, since these hormones appear to be intimately associated with blood pressure and intravascular volume homeostasis. ANP was found to increase cyclic GMP accumulation in ten cell culture systems, which were derived from blood vessels, adrenal cortex, kidney, lung, testes and mammary gland. ANP receptors were characterized in intact cultured cells using 125I-ANP8-33. Specific 125I-ANP binding was saturable and of high affinity. Scratchard analysis of the binding data for all cell types exhibited a straight line, indicating that these cells possessed a single class of binding sites. Despite the presence of linear Scatchard plots, these studies demonstrated that cultured cells possess two functionally and physically distinct ANP-binding sites. Most of the ANP-binding sites in cultured cells have a molecular size of 66,000 daltons under reducing conditions. The identification of cultured cell types in which hormones (ANP and oxytocin) regulate guanylate cyclase activity and increase cyclic GMP synthesis will provide valuable systems to determine the mechanisms of hormone-receptor coupling to guanylate cyclase and the cellular processes regulated by cyclic GMP

  18. Atrial natriuretic peptide receptor heterogeneity and effects on cyclic GMP accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Leitman, D.C.

    1988-01-01

    The effects of atrial natriuretic peptide (ANP), oxytocin (OT) and vasopressin (AVP) on guanylate cyclase activity and cyclic GMP accumulation were examined, since these hormones appear to be intimately associated with blood pressure and intravascular volume homeostasis. ANP was found to increase cyclic GMP accumulation in ten cell culture systems, which were derived from blood vessels, adrenal cortex, kidney, lung, testes and mammary gland. ANP receptors were characterized in intact cultured cells using {sup 125}I-ANP{sub 8-33}. Specific {sup 125}I-ANP binding was saturable and of high affinity. Scratchard analysis of the binding data for all cell types exhibited a straight line, indicating that these cells possessed a single class of binding sites. Despite the presence of linear Scatchard plots, these studies demonstrated that cultured cells possess two functionally and physically distinct ANP-binding sites. Most of the ANP-binding sites in cultured cells have a molecular size of 66,000 daltons under reducing conditions. The identification of cultured cell types in which hormones (ANP and oxytocin) regulate guanylate cyclase activity and increase cyclic GMP synthesis will provide valuable systems to determine the mechanisms of hormone-receptor coupling to guanylate cyclase and the cellular processes regulated by cyclic GMP.

  19. Why Shared Understanding Matters : Engineering a Collaboration Process for Shared Understanding to Improve Collaboration Effectiveness in Heterogeneous Teams

    OpenAIRE

    Bittner, E.; Leimeister, Jan Marco

    2013-01-01

    Solving complex problems often requires experience and perspectives of various, often heterogeneous experts. Shared understanding of the task is an important determinant for the performance of collaborative groups [1, 2]. Surprisingly little attention has been paid to the systematic development of processes that lead to a shared understanding within heterogeneous groups. To address this challenge, we provide a systematic, reusable process to support groups to converge towards a shared underst...

  20. Effect of Small-Scale Heterogeneity of Prey and Hunter Distributions on the Sustainability of Bushmeat Hunting

    OpenAIRE

    Van Vliet, Nathalie; E. J. Milner-Gulland; Bousquet, François; Saqalli, Mehdi; Nasi, Robert

    2010-01-01

    Bushmeat is the main source of protein and the most important source of income for rural people in the Congo Basin, but intensive hunting of bushmeat species is also a major concern for conservationists. Although spatial heterogeneity in hunting effort and in prey populations at the landscape level plays a key role in the sustainability of hunted populations, the role of small-scale heterogeneity within a village hunting territory in the sustainability of hunting has remained understudied. We...

  1. The effect of ozone on nicotine desorption from model surfaces:evidence for heterogeneous chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Destaillats, Hugo; Singer, Brett C.; Lee, Sharon K.; Gundel, LaraA.

    2005-05-01

    Assessment of secondhand tobacco smoke exposure using nicotine as a tracer or biomarker is affected by sorption of the alkaloid to indoor surfaces and by its long-term re-emission into the gas phase. However, surface chemical interactions of nicotine have not been sufficiently characterized. Here, the reaction of ozone with nicotine sorbed to Teflon and cotton surfaces was investigated in an environmental chamber by monitoring nicotine desorption over a week following equilibration in dry or humid air (65-70 % RH). The Teflon and cotton surfaces had N{sub 2}-BET surface areas of 0.19 and 1.17 m{sup 2} g{sup -1}, and water mass uptakes (at 70 % RH) of 0 and 7.1 % respectively. Compared with dry air baseline levels in the absence of O{sub 3}, gas phase nicotine concentrations decrease, by 2 orders of magnitude for Teflon after 50 h at 20-45 ppb O{sub 3}, and by a factor of 10 for cotton after 100 h with 13-15 ppb O{sub 3}. The ratios of pseudo first-order rate constants for surface reaction (r) to long-term desorption (k) were r/k = 3.5 and 2.0 for Teflon and cotton surfaces, respectively. These results show that surface oxidation was competitive with desorption. Hence, oxidative losses could significantly reduce long-term re-emissions of nicotine from indoor surfaces. Formaldehyde, N-methylformamide, nicotinaldehyde and cotinine were identified as oxidation products, indicating that the pyrrolidinic N was the site of electrophilic attack by O{sub 3}. The presence of water vapor had no effect on the nicotine-O{sub 3} reaction on Teflon surfaces. By contrast, nicotine desorption from cotton in humid air was unaffected by the presence of ozone. These observations are consistent with complete inhibition of ozone-nicotine surface reactions in an aqueous surface film present in cotton but not in Teflon surfaces.

  2. Investigating spatial self-shielding and temperature effects for homogeneous and double heterogeneous pebble models with MCNP

    International Nuclear Information System (INIS)

    The gas-cooled, high temperature reactor (HTR) represents a valuable option for the future development of nuclear technology, because of its excellent safety features. One main safety feature is the negative temperature coefficient which is due to the Doppler broadening of the (n,y) resonance absorption cross section. A second important effect is the spatial self-shielding due to the double heterogeneous geometry of a pebble bed reactor. At FZ-Juelich two reactor analysis codes have been developed: VSOP for core design and MGT for transient analysis. Currently an update of the nuclear cross section libraries to ENDF/B-VII.0 of both codes takes place. In order to take the temperature dependency as well as the spatial self-shielding into account the absorption cross sections σ(n,y) for the resonance absorbers like 232Th and 238U have to be provided as function of incident neutron energy, temperature and nuclide concentration. There are two reasons for choosing the Monte-Carlo approach to calculate group wise cross sections. First, the former applied ZUT-DGL code to generate the resonance cross section tables for MGT is so far not able to handle the new resonance description based on Reich-Moore instead of Single-level Breit-Wigner. Second, the rising interest in PuO2 fuel motivated an investigation on the generation of group wise cross sections describing thermal resonances of 240Pu and 242Pu. (orig.)

  3. Effect of Pore-Scale Heterogeneity and Capillary-Viscous Fingering on Commingled Waterflood Oil Recovery in Stratified Porous Media

    Directory of Open Access Journals (Sweden)

    Emad W. Al-Shalabi

    2016-01-01

    Full Text Available Oil recovery prediction and field pilot implements require basic understanding and estimation of displacement efficiency. Corefloods and glass micromodels are two of the commonly used experimental methods to achieve this. In this paper, waterflood recovery is investigated using layered etched glass micromodel and Berea sandstone core plugs with large permeability contrasts. This study focuses mainly on the effect of permeability (heterogeneity in stratified porous media with no cross-flow. Three experimental setups were designed to represent uniformly stratified oil reservoir with vertical discontinuity in permeability. Waterflood recovery to residual oil saturation (Sor is measured through glass micromodel (to aid visual observation, linear coreflood, and forced drainage-imbibition processes by ultracentrifuge. Six oil samples of low-to-medium viscosity and porous media of widely different permeability (darcy and millidarcy ranges were chosen for the study. The results showed that waterflood displacement efficiencies are consistent in both permeability ranges, namely, glass micromodel and Berea sandstone core plugs. Interestingly, the experimental results show that the low permeability zones resulted in higher ultimate oil recovery compared to high permeability zones. At Sor microheterogeneity and fingering are attributed for this phenomenon. In light of the findings, conformance control is discussed for better sweep efficiency. This paper may be of help to field operators to gain more insight into microheterogeneity and fingering phenomena and their impact on waterflood recovery estimation.

  4. Effect of heterogeneous distribution of crosslink density on physical properties of radiation vulcanized NR (Natural Rubber) latex film

    International Nuclear Information System (INIS)

    Thus a study has been carried out to investigate the effect of particle to particle variation in crosslink density on physical properties of radiation vulcanized NR latex film. NR latex was irradiated in small bottle by γ rays without vulcanization accelerator to provide latex rubber particles having homogeneous distribution of crosslink density. The doses were 30, 50, 100, 250, 300, 400, 500 and 600 kGy. Weight swelling ratio, gel fraction, tensile strength and elongation at break of the latex film from the mixed latex were measured. The vulcanization dose of this latex was 250 kGy. Then the two different latexes were mixed in a such way to adjust the average dose of 250 kGy to prepare a latex consisting of rubber particles having heterogeneous distribution of crosslink density. Tensile strength of the latex film was depressed by mixing. The reduction increased with increasing the decrease of gel fraction by mixing. However the reduction was not serious when the dose difference of two latexes was less than 200 kGy

  5. Effect of chemical heterogeneity of biodegradable polymers on surface energy: A static contact angle analysis of polyester model films.

    Science.gov (United States)

    Belibel, R; Avramoglou, T; Garcia, A; Barbaud, C; Mora, L

    2016-02-01

    Biodegradable and bioassimilable poly((R,S)-3,3 dimethylmalic acid) (PDMMLA) derivatives were synthesized and characterized in order to develop a new coating for coronary endoprosthesis enabling the reduction of restenosis. The PDMMLA was chemically modified to form different custom groups in its side chain. Three side groups were chosen: the hexyl group for its hydrophobic nature, the carboxylic acid and alcohol groups for their acid and neutral hydrophilic character, respectively. The sessile drop method was applied to characterize the wettability of biodegradable polymer film coatings. Surface energy and components were calculated. The van Oss approach helped reach not only the dispersive and polar acid-base components of surface energy but also acid and basic components. Surface topography was quantified by atomic force microscopy (AFM) and subnanometer average values of roughness (Ra) were obtained for all the analyzed surfaces. Thus, roughness was considered to have a negligible effect on wettability measurements. In contrast, heterogeneous surfaces had to be corrected by the Cassie-Baxter equation for copolymers (10/90, 20/80 and 30/70). The impact of this correction was quantified for all the wettability parameters. Very high relative corrections (%) were found, reaching 100% for energies and 30% for contact angles. PMID:26652458

  6. Heterogeneous effects of antiepileptic drugs in an in vitro epilepsy model--a functional multineuron calcium imaging study.

    Science.gov (United States)

    Hongo, Yoshie; Takasu, Keiko; Ikegaya, Yuji; Hasegawa, Minoru; Sakaguchi, Gaku; Ogawa, Koichi

    2015-07-01

    Epilepsy is a chronic brain disease characterised by recurrent seizures. Many studies of this disease have focused on local neuronal activity, such as local field potentials in the brain. In addition, several recent studies have elucidated the collective behavior of individual neurons in a neuronal network that emits epileptic activity. However, little is known about the effects of antiepileptic drugs on neuronal networks during seizure-like events (SLEs) at single-cell resolution. Using functional multineuron Ca(2+) imaging (fMCI), we monitored the activities of multiple neurons in the rat hippocampal CA1 region on treatment with the proconvulsant bicuculline under Mg(2+) -free conditions. Bicuculline induced recurrent synchronous Ca(2+) influx, and the events were correlated with SLEs. Other proconvulsants, such as 4-aminopyridine, pentetrazol, and pilocarpine, also induced synchronous Ca(2+) influx. We found that the antiepileptic drugs phenytoin, flupirtine, and ethosuximide, which have different mechanisms of action, exerted heterogeneous effects on bicuculline-induced synchronous Ca(2+) influx. Phenytoin and flupirtine significantly decreased the peak, the amount of Ca(2+) influx and the duration of synchronous events in parallel with the duration of SLEs, whereas they did not abolish the synchronous events themselves. Ethosuximide increased the duration of synchronous Ca(2+) influx and SLEs. Furthermore, the magnitude of the inhibitory effect of phenytoin on the peak synchronous Ca(2+) influx level differed according to the peak amplitude of the synchronous event in each individual cell. Evaluation of the collective behavior of individual neurons by fMCI seems to be a powerful tool for elucidating the profiles of antiepileptic drugs. PMID:25967117

  7. Spatial Heterogeneity of Climate Change Effects on Dominant Height of Larch Plantations in Northern and Northeastern China

    Directory of Open Access Journals (Sweden)

    Hao Zang

    2016-07-01

    Full Text Available Determining the response of dominant height growth to climate change is important for understanding adaption strategies. Based on 550 permanent plots from a national forest inventory and climate data across seven provinces and three climate zones, we developed a climate-sensitive dominant height growth model under a mixed-effects model framework. The mean temperature of the wettest quarter and precipitation of the wettest month were found to be statistically significant explanatory variables that markedly improved model performance. Generally, future climate change had a positive effect on stand dominant height in northern and northeastern China, but the effect showed high spatial variability linked to local climatic conditions. The range in dominant height difference between the current climate and three future BC-RCP scenarios would change from −0.61 m to 1.75 m (−6.9% to 13.5% during the period 2041–2060 and from −1.17 m to 3.28 m (−9.1% to 41.0% during the period 2061–2080 across provinces. The impacts of climate change on stand dominant height decreased as stand age increased. Forests in cold and warm temperate zones had a smaller decrease in dominant height, owing to climate change, compared with those in the mid temperate zone. Overall, future climate change could impact dominant height growth in northern and northeastern China. As spatial heterogeneity of climate change affects dominant height growth, locally specific mitigation measures should be considered in forest management.

  8. Factors explaining the heterogeneity of effects of patient decision aids on knowledge of outcome probabilities: a systematic review sub-analysis

    OpenAIRE

    Gentles, Stephen J; Stacey, Dawn; Bennett, Carol; Alshurafa, Mohamad; Walter, Stephen D.

    2013-01-01

    Background There is considerable unexplained heterogeneity in previous meta-analyses of randomized controlled trials (RCTs) evaluating the effects of patient decision aids on the accuracy of knowledge of outcome probabilities. The purpose of this review was to explore possible effect modification by three covariates: the type of control intervention, decision aid quality and patients' baseline knowledge of probabilities. Methods A sub-analysis of studies previously identified in the 2011 Coch...

  9. Ancient earthen constructions and antiseismic dwellings: Boni's project after the earthquake of 13th January 1915 (Avezzano, Italy)

    OpenAIRE

    E. M. Beranger

    1995-01-01

    After the earthquake of 13th January 1915, the archaeologist Giacomo Boni (1859-1925), inspired by ancient building techniques. proposed the reconstruction of Marsica and the Middle Liri Valley with earthen dwellings. With the cooperation of the Italian Ministry of Agriculture, he organized an exhibition where he collected samples of vegetal trellises which were an essential support to implement these techniques. Furthermore, he rebuilt two huts on the Palatine (Orti Farnesiani): ...

  10. The characteristics of bony ankylosis of the facet joint of the upper cervical spine in rheumatoid arthritis patients

    OpenAIRE

    Iizuka, Haku; Nishinome, Masahiro; Sorimachi, Yasunori; Ara, Tsuyoshi; Nakajima, Takashi; Iizuka, Yoichi; Takagishi, Kenji

    2009-01-01

    This study investigated the bony ankylosis of the upper cervical spine facet joints in patients with a cervical spine involvement due to rheumatoid arthritis (RA) using computed tomography (CT) and then examined the characteristics of the patients showing such ankylosis. Forty-six consecutive patients who underwent surgical treatment for RA involving the cervical spine were reviewed. The radiographic diagnoses included atlanto-axial subluxation in 30 cases, vertical subluxation (VS) in 10 cas...

  11. Histochemical demonstration of aluminum and iron deposition in pulmonary bony tissues in three cases of diffuse pulmonary ossification

    OpenAIRE

    Ohtsuki,Yuji; Yamanaka, Akira; Ohyama, Hideki; Yamada, Eiji; Terada, Nobuyuki; Fujita, Jiro; LEE, GANG-HONG; Furihata, Mutsuo

    2008-01-01

    Diffuse pulmonary ossification is a rare condition. We examined three cases of it in Japan, and attempted histochemically to stain for deposition of aluminum and iron in bony tissues. The patients were all female, and in their mid-twenties, mid- eighties, and later teen years. One of the patients had been exposed to heavy metals in her work involving heavy-metal analyses for 18 months. Aluminum staining and Berlin blue staining for iron were performed with dewaxed, ...

  12. Determination of prevalence of glenoid bony lesions after recurrent anterior shoulder dislocation using the 3-D CT scan

    OpenAIRE

    Guity, Mohamad Reza; Akhlaghpour, Shaharam; Yousefian, Reza

    2014-01-01

    Background: Glenoid bone damages consisting of anterior rim erosion and bony avulsion are very important in decision making for treatment of recurrent dislocation in shoulder joint. This study was aimed to determine the prevalence of these damages in patients with anterior recurrent shoulder dislocation. Methods: The study was a cross-sectional study evaluating patients with unstable shoulder joint. Glenoid bone damage was assessed using three dimensional (CT) scan implementing either glenoid...

  13. Biosafety of the Novel Vancomycin-loaded Bone-like Hydroxyapatite/Poly-amino Acid Bony Scaffold

    Directory of Open Access Journals (Sweden)

    Zhi-Dong Cao

    2016-01-01

    Full Text Available Background: Recently, local sustained-release antibiotics systems have been developed because they can increase local foci of concentrated antibiotics without increasing the plasma concentration, and thereby effectively decrease any systemic toxicity and side effects. A vancomycin-loaded bone-like hydroxyapatite/poly-amino acid (V-BHA/PAA bony scaffold was successfully fabricated with vancomycin-loaded poly lactic-co-glycolic acid microspheres and BHA/PAA, which was demonstrated to exhibit both porosity and perfect biodegradability. The aim of this study was to systematically evaluate the biosafety of this novel scaffold by conducting toxicity tests in vitro and in vivo. Methods: According to the ISO rules for medical implant biosafety, for in vitro tests, the scaffold was incubated with L929 fibroblasts or rabbit noncoagulant blood, with simultaneous creation of positive control and negative control groups. The growth condition of L929 cells and hemolytic ratio were respectively evaluated after various incubation periods. For in vivo tests, a chronic osteomyelitis model involving the right proximal tibia of New Zealand white rabbits was established. After bacterial identification, the drug-loaded scaffold, drug-unloaded BHA/PAA, and poly (methyl methacrylate were implanted, and a blank control group was also set up. Subsequently, the in vivo blood drug concentrations were measured, and the kidney and liver functions were evaluated. Results: In the in vitro tests, the cytotoxicity grades of V-BHA/PAA and BHA/PAA-based on the relative growth rate were all below 1. The hemolysis ratios of V-BHA/PAA and BHA/PAA were 2.27% and 1.42%, respectively, both below 5%. In the in vivo tests, the blood concentration of vancomycin after implantation of V-BHA/PAA was measured at far below its toxic concentration (60 mg/L, and the function and histomorphology of the liver and kidney were all normal. Conclusion: According to ISO standards, the V-BHA/PAA scaffold

  14. Statistical analysis of DUPIC fuel composition heterogeneity

    International Nuclear Information System (INIS)

    The fuel composition heterogeneity effect on reactor performance parameters was assessed by refueling simulations for the reference DUPIC fuel model. The refueling simulation was performed using 30 heterogeneous fuel types which were determined by the agglomerative hierarchical clustering method. The heterogeneity effect was considered during the refueling simulation by randomly selecting fuel types for the refueling operation. The refueling simulations of the heterogeneous core have shown that the key performance parameters are close to those of the core that has single fuel type. The uncertainties of the maximum channel power, maximum bundle power, and channel power peaking factor due to the fuel composition heterogeneity are 0.5, 0.7, and 0.8%, respectively, including the uncertainty of the group-average fuel property. This study has shown that the reference DUPIC fuel option reduces the composition heterogeneity effectively and the zone controller unit has a sufficient margin to adjust the perturbations caused by the fuel composition heterogeneity

  15. Coupling groundwater and land surface processes: Idealized simulations to identify effects of terrain and subsurface heterogeneity on land surface energy fluxes

    Science.gov (United States)

    Rihani, Jehan F.; Maxwell, Reed M.; Chow, Fotini K.

    2010-12-01

    This work investigates the role of terrain and subsurface heterogeneity on the interactions between groundwater dynamics and land surface energy fluxes using idealized simulations. A three-dimensional variably saturated groundwater code (ParFlow) coupled to a land surface model (Common Land Model) is used to account for both vertical and lateral water and pressure movement. This creates a fully integrated approach, coupling overland and subsurface flow while having an explicit representation of the water table and all land surface processes forced by atmospheric data. Because the water table is explicitly represented in these simulations, regions with stronger interaction between water table depth and the land surface energy balance (known as critical zones) can be identified. This study uses simple terrain and geologic configurations to demonstrate the importance of lateral surface and subsurface flows in determining land surface heat and moisture fluxes. Strong correlations are found between the land surface fluxes and water table depth across all cases, including terrain shape, subsurface heterogeneity, vegetation type, and climatological region. Results show that different land forms and subsurface heterogeneities produce very different water table dynamics and land surface flux responses to atmospheric forcing. Subsurface formation and properties have the greatest effect on the coupling between the water table and surface heat and moisture fluxes. Changes in landform and land surface slope also have an effect on these interactions by influencing the fraction of rainfall contributing to overland flow versus infiltration. This directly affects the extent of the critical zone with highest coupling strength along the hillside. Vegetative land cover, as seen in these simulations, has a large effect on the energy balance at the land surface but a small effect on streamflow and water table dynamics and thus a limited impact on the land surface-subsurface interactions

  16. Effect of Support in Heterogeneous Ruthenium Catalysts Used for the Selective Aerobic Oxidation of HMF in Water

    DEFF Research Database (Denmark)

    Gorbanev, Yury; Kegnæs, Søren; Riisager, Anders

    2011-01-01

    Heterogeneous ruthenium-based catalysts were applied in the selective, aerobic oxidation of 5-hydroxymethylfurfural, a versatile biomass-derived chemical, to form 2,5-furandicarboxylic acid. The oxidation reactions were performed in water with dioxygen as the oxidant at different pressures without...

  17. The effect of entrapped nonaqueous phase liquids on tracer transport in heterogeneous porous media: Laboratory experiments at the intermediate scale

    Science.gov (United States)

    Barth, G.R.; Illangasekare, T.H.; Rajaram, H.

    2003-01-01

    This work considers the applicability of conservative tracers for detecting high-saturation nonaqueous-phase liquid (NAPL) entrapment in heterogeneous systems. For this purpose, a series of experiments and simulations was performed using a two-dimensional heterogeneous system (10??1.2 m), which represents an intermediate scale between laboratory and field scales. Tracer tests performed prior to injecting the NAPL provide the baseline response of the heterogeneous porous medium. Two NAPL spill experiments were performed and the entrapped-NAPL saturation distribution measured in detail using a gamma-ray attenuation system. Tracer tests following each of the NAPL spills produced breakthrough curves (BTCs) reflecting the impact of entrapped NAPL on conservative transport. To evaluate significance, the impact of NAPL entrapment on the conservative-tracer breakthrough curves was compared to simulated breakthrough curve variability for different realizations of the heterogeneous distribution. Analysis of the results reveals that the NAPL entrapment has a significant impact on the temporal moments of conservative-tracer breakthrough curves. ?? 2003 Elsevier B.V. All rights reserved.

  18. Average partial effects in multivariate probit models with latent heterogeneity: Monte Carlo experiments and an application to immigrants' ethnic identity and economic performance

    OpenAIRE

    Giovanni Bruno; Orietta Dessy

    2014-01-01

    We extend the univariate results in Wooldridge (2005) to multivariate probit models, proving the following. 1) Average partial effects (APEs) based on joint probabilities are consistently estimated by conventional multivariate probit models under general forms of conditionally independent latent heterogeneity (LH) as long as the only constraints beyond normalization, if any, are within-equation homogenous restrictions. The normalization of choice is not neutral to consistency in models with c...

  19. Elevational pattern of species richness in the Three Gorges region of the Yangtze River: effect of climate, geometric constraints, area and topographical heterogeneity

    OpenAIRE

    Qiaoyan Li; Xiangping Wang

    2013-01-01

    In this paper, we explore altitudinal richness of vascular plant species in the Three Gorges region of the Yangtze River and test several hypotheses concerning geographic diversity patterns. Multivariate regression and variation partitioning analyses were used to examine the relative effects of area, climate, geometric constraints and topographical heterogeneity on altitudinal richness patterns, and also the differences among ecological groups (including species with different range sizes, gr...

  20. Effects of land use and fine-scale environmental heterogeneity on net ecosystem production over a temperate coniferous forest landscape

    International Nuclear Information System (INIS)

    In temperate coniferous forests, spatial variation in net ecosystem production (NEP) is often associated with variation in stand age and heterogeneity in environmental factors such as soil depth. However, coarse spatial resolution analyses used to evaluate the terrestrial contribution to global NEP do not generally incorporate these effects. In this study, a fine-scale (25 m grid) analysis of NEP over a 164-km2 area of productive coniferous forests in the Pacific Northwest region of the United States was made to evaluate the effects of including fine scale information in landscape-scale NEP assessments. The Enhanced Thematic Mapper (ETM+) sensor resolved five cover classes in the study area and further differentiated between young, mature and old-growth conifer stands. ETM+ was also used to map current leaf area index (LAI) based on an empirical relationship of observed LAI to spectral vegetation indices. A daily time step climatology, based on 18 years of meteorological observations, was distributed (1 km resolution) over the mountainous terrain of the study area using the DAYMET model. Estimates of carbon pools and flux associated with soil, litter, coarse woody debris and live trees were then generated by running a carbon cycle model (Biome-BGC) to a state that reflected the current successional status and LAI of each grid cell, as indicated by the remote sensing observations. Estimated annual NEP for 1997 over the complete study area averaged 230 g C m2, with most of the area acting as a carbon sink. The area-wide NEP is strongly positive because of reduced harvesting in the last decade and the recovery of areas harvested between 1940 and 1990. The average value was greater than would be indicated if the entire area was assumed to be a mature conifer stand, as in a coarse-scale analysis. The mean NEP varied interannually by over a factor of two. This variation was 38% less than the interannual variation for a single point. The integration of process models with

  1. Heterogeneity and Microeconometrics Modelling

    DEFF Research Database (Denmark)

    Browning, Martin; Carro, Jesus

    Presented at the 2005 Econometric Society World Congress Plenary Session on "Modelling Heterogeneity". We survey the treatment of heterogeneity in applied microeconometrics analyses. There are three themes. First, there is usually much more heterogeneity than empirical researchers allow for. Seco...... structures. The latter task is one for economists: "heterogeneity is too important to be left to the statisticians". The paper concludes with a report of our own research on dynamic discrete choice models that allow for maximal heterogeneity...

  2. EFFECTS OF PORE STRUCTURE CHANGE AND MULTI-SCALE HETEROGENEITY ON CONTAMINANT TRANSPORT AND REACTION RATE UPSCALING

    Energy Technology Data Exchange (ETDEWEB)

    Lindquist, W. Brent; Jones, Keith W.; Um, Wooyong; Rockhold, mark; Peters, Catherine A.; Celia, Michael A.

    2013-02-15

    This project addressed the scaling of geochemical reactions to core and field scales, and the interrelationship between reaction rates and flow in porous media. We targeted reactive transport problems relevant to the Hanford site - specifically the reaction of highly caustic, radioactive waste solutions with subsurface sediments, and the immobilization of 90Sr and 129I through mineral incorporation and passive flow blockage, respectively. We addressed the correlation of results for pore-scale fluid-soil interaction with field-scale fluid flow, with the specific goals of (i) predicting attenuation of radionuclide concentration; (ii) estimating changes in flow rates through changes of soil permeabilities; and (iii) estimating effective reaction rates. In supplemental work, we also simulated reactive transport systems relevant to geologic carbon sequestration. As a whole, this research generated a better understanding of reactive transport in porous media, and resulted in more accurate methods for reaction rate upscaling and improved prediction of permeability evolution. These scientific advancements will ultimately lead to better tools for management and remediation of DOE’s legacy waste problems. We established three key issues of reactive flow upscaling, and organized this project in three corresponding thrust areas. 1) Reactive flow experiments. The combination of mineral dissolution and precipitation alters pore network structure and the subsequent flow velocities, thereby creating a complex interaction between reaction and transport. To examine this phenomenon, we conducted controlled laboratory experimentation using reactive flow-through columns. Results and Key Findings: Four reactive column experiments (S1, S3, S4, S5) have been completed in which simulated tank waste leachage (STWL) was reacted with pure quartz sand, with and without Aluminum. The STWL is a caustic solution that dissolves quartz. Because Al is a necessary element in the formation of

  3. Evaluation of the effects of microscale chemical and isotopic heterogeneity of coral skeleton on conventional Sr/Ca and O paleothermometers

    Science.gov (United States)

    Mitsuguchi, Takehiro

    2013-10-01

    Recent studies using secondary ion mass spectrometry revealed microscale heterogeneity of Sr/Ca and O in shallow-water coral skeletons, i.e., Sr/Ca and O differ significantly between two basic microfeatures of the skeleton: the center of calcification (COC) and surrounding fibrous skeleton (SFS). The COC, in contrast with the SFS, consists of highly irregular crystals intermingled with significant amount of organic matter; therefore, analyzing the SFS only would probably be favourable for paleotemperature reconstruction. Conventional Sr/Ca and O paleothermometers are, however, based on the analysis of the mixture of the COC and SFS, and thus may be significantly affected by the above-mentioned heterogeneity. In this study, I have evaluated the heterogeneity-induced effects on the conventional paleothermometers of Porites skeletons using published Sr/Ca, O and volume-fraction data of the COC and SFS and published observations of seasonal variability of bulk skeletal density. Results indicate that the effects may yield significant or serious errors in paleotemperature reconstruction.

  4. Sample of EDF-R&D 2009-2012 core studies on heterogeneous sodium-cooled fast reactors with low sodium void effect

    International Nuclear Information System (INIS)

    The unprotected loss of primary or/and secondary pumps transient is often used as a reference initiator to evaluate the intrinsic behaviour of SFR cores. Traditional designs show a major positive sodium reactivity feedback during this transient and many studies were led in the past to get rid of that effect. In 2009-2012, consistently with researches led at CEA and AREVA, cores with low sodium void effect were studied and optimized at EDF-R&D. The use of a sodium plenum with a boron carbide plate, a reduction of the fissile height, or a step-wise modulation of the fissile height can be used to reduce the sodium void worth. To go further, neutronic leakage can be enhanced using axial or radial heterogeneities. Axial heterogeneity is the basis of the CFV CEA concept. An analysis of this design using an EDF optimization methodology led to a better understanding and allowed to define core variants. As far as radial heterogeneities are concerned, various configurations featuring annular shapes, fertile sub-assembly rings and modulations of the fissile height are presented in this paper. One of these concepts is applied on a 600 MWe scale and compared to a CFV-like core. This paper aims at giving an overview of EDF-R&D core design studies on the time period 2009-2012, and concludes on perspectives for future work. (author)

  5. Prenatal Maternal Anxiety as a Risk Factor for Preterm Birth and the Effects of Heterogeneity on This Relationship: A Systematic Review and Meta-Analysis

    Science.gov (United States)

    Rose, M. Sarah; Pana, Gianella; Premji, Shahirose

    2016-01-01

    Background. Systematic reviews (SR) and meta-analyses (MA) that previously explored the relationship between prenatal maternal anxiety (PMA) and preterm birth (PTB) have not been comprehensive in study inclusion, failing to account for effects of heterogeneity and disagree in their conclusions. Objectives. This SRMA provides a summary of the published evidence of the relationship between PMA and PTB while examining methodological and statistical sources of heterogeneity. Methods. Published studies from MEDLINE, CINAHL, PsycINFO, and EMBASE, until June 2015, were extracted and reviewed. Results. Of the 37 eligible studies, 31 were used in this MA; six more were subsequently excluded due to statistical issues, substantially reducing the heterogeneity. The odds ratio for PMA was 1.70 (95% CI 1.33, 2.18) for PTB and 1.67 (95% CI 1.35, 2.07) for spontaneous PTB comparing higher levels of anxiety to lower levels. Conclusions. Consistent findings indicate a significant association between PMA and PTB. Due to the statistical problem of including collinear variables in a single regression model, it is hard to distinguish the effect of the various types of psychosocial distress on PTB. However, a prenatal program aimed at addressing mental health issues could be designed and evaluated using a randomised controlled trial to assess the causal nature of different aspects of mental health on PTB. PMID:27298829

  6. Prenatal Maternal Anxiety as a Risk Factor for Preterm Birth and the Effects of Heterogeneity on This Relationship: A Systematic Review and Meta-Analysis

    Directory of Open Access Journals (Sweden)

    M. Sarah Rose

    2016-01-01

    Full Text Available Background. Systematic reviews (SR and meta-analyses (MA that previously explored the relationship between prenatal maternal anxiety (PMA and preterm birth (PTB have not been comprehensive in study inclusion, failing to account for effects of heterogeneity and disagree in their conclusions. Objectives. This SRMA provides a summary of the published evidence of the relationship between PMA and PTB while examining methodological and statistical sources of heterogeneity. Methods. Published studies from MEDLINE, CINAHL, PsycINFO, and EMBASE, until June 2015, were extracted and reviewed. Results. Of the 37 eligible studies, 31 were used in this MA; six more were subsequently excluded due to statistical issues, substantially reducing the heterogeneity. The odds ratio for PMA was 1.70 (95% CI 1.33, 2.18 for PTB and 1.67 (95% CI 1.35, 2.07 for spontaneous PTB comparing higher levels of anxiety to lower levels. Conclusions. Consistent findings indicate a significant association between PMA and PTB. Due to the statistical problem of including collinear variables in a single regression model, it is hard to distinguish the effect of the various types of psychosocial distress on PTB. However, a prenatal program aimed at addressing mental health issues could be designed and evaluated using a randomised controlled trial to assess the causal nature of different aspects of mental health on PTB.

  7. Evaluation of the effects of microscale chemical and isotopic heterogeneity of coral skeleton on conventional Sr/Ca and 18O paleothermometers

    Indian Academy of Sciences (India)

    Takehiro Mitsuguchi

    2013-10-01

    Recent studies using secondary ion mass spectrometry revealed microscale heterogeneity of Sr/Ca and 18O in shallow-water coral skeletons, i.e., Sr/Ca and 18O differ significantly between two basic microfeatures of the skeleton: the center of calcification (COC) and surrounding fibrous skeleton (SFS). The COC, in contrast with the SFS, consists of highly irregular crystals intermingled with significant amount of organic matter; therefore, analyzing the SFS only would probably be favourable for paleotemperature reconstruction. Conventional Sr/Ca and 18O paleothermometers are, however, based on the analysis of the mixture of the COC and SFS, and thus may be significantly affected by the above-mentioned heterogeneity. In this study, I have evaluated the heterogeneity-induced effects on the conventional paleothermometers of Porites skeletons using published Sr/Ca, 18O and volume-fraction data of the COC and SFS and published observations of seasonal variability of bulk skeletal density. Results indicate that the effects may yield significant or serious errors in paleotemperature reconstruction.

  8. Effect of Manganese Sulphide Size on the Precipitation of Tin Heterogeneous Nucleation in as-Cast Steel

    Science.gov (United States)

    Sun, Guilin; Song, Bo; Tao, Sufen; Cai, Zeyun

    2015-05-01

    Tramp elements in steels such as tin have been thought harmful because of the hot brittleness at grain boundaries and will be enriched in new steels because of difficulty of removal. It has been an important and difficult matter for metallurgist to use these elements. In the present paper, the as-cast steel containing high concentration of tin is prepared in laboratory and tin precipitates at the manganese sulphide inclusions have been found. A theoretical model is established to calculate the size of manganese sulphide inclusions acted as the heterogeneous nucleation site of tin precipitation. The results show that the inclusions with the smaller contact angle between tin precipitate is more advantageous to be the nucleus of tin heterogeneous nucleation. In this experiment, the manganese sulphide inclusions whose size is 2~4 μm in diameter can act as the nuclei of the nucleation of tin precipitation.

  9. Effects of dynamic heterogeneity and density scaling of molecular dynamics on the relationship among thermodynamic coefficients at the glass transition

    International Nuclear Information System (INIS)

    In this paper, we define and experimentally verify thermodynamic characteristics of the liquid-glass transition, taking into account a kinetic origin of the process. Using the density scaling law and the four-point measure of the dynamic heterogeneity of molecular dynamics of glass forming liquids, we investigate contributions of enthalpy, temperature, and density fluctuations to spatially heterogeneous molecular dynamics at the liquid-glass transition, finding an equation for the pressure coefficient of the glass transition temperature, dTg/dp. This equation combined with our previous formula for dTg/dp, derived solely from the density scaling criterion, implies a relationship among thermodynamic coefficients at Tg. Since this relationship and both the equations for dTg/dp are very well validated using experimental data at Tg, they are promising alternatives to the classical Prigogine-Defay ratio and both the Ehrenfest equations in case of the liquid-glass transition

  10. Fine Mapping Seronegative and Seropositive Rheumatoid Arthritis to Shared and Distinct HLA Alleles by Adjusting for the Effects of Heterogeneity

    OpenAIRE

    Han, Buhm; Diogo, Dorothée; Eyre, Steve; Kallberg, Henrik; Zhernakova, Alexandra; Bowes, John; Padyukov, Leonid; Okada, Yukinori; González-Gay, Miguel A.; Rantapää-Dahlqvist, Solbritt; Martin, Javier; Huizinga, Tom W.J.; Plenge, Robert M.; Worthington, Jane; Gregersen, Peter K.

    2014-01-01

    Despite progress in defining human leukocyte antigen (HLA) alleles for anti-citrullinated-protein-autoantibody-positive (ACPA+) rheumatoid arthritis (RA), identifying HLA alleles for ACPA-negative (ACPA−) RA has been challenging because of clinical heterogeneity within clinical cohorts. We imputed 8,961 classical HLA alleles, amino acids, and SNPs from Immunochip data in a discovery set of 2,406 ACPA− RA case and 13,930 control individuals. We developed a statistical approach to identify and ...

  11. DNA fingerprinting for forensic identification: potential effects on data interpretation of subpopulation heterogeneity and band number variability.

    OpenAIRE

    Cohen, J E

    1990-01-01

    Some methods of statistical analysis of data on DNA fingerprinting suffer serious weaknesses. Unlinked Mendelizing loci that are at linkage equilibrium in subpopulations may be statistically associated, not statistically independent, in the population as a whole if there is heterogeneity in gene frequencies between subpopulations. In the populations where DNA fingerprinting is used for forensic applications, the assumption that DNA fragments occur statistically independently for different pro...

  12. Classification of Neuronal Subtypes in the Striatum and the Effect of Neuronal Heterogeneity on the Activity Dynamics

    OpenAIRE

    Bekkouche, Bo

    2016-01-01

    Clustering of single-cell RNA sequencing data is often used to show what states and subtypes cells have. Using this technique, striatal cells were clustered into subtypes using different clustering algorithms. Previously known subtypes were confirmed and new subtypes were found. One of them is a third medium spiny neuron subtype. Using the observed heterogeneity, as a second task, this project questions whether or not differences in individual neurons have an impact on the network dynamics. B...

  13. Effects of Nutrient Heterogeneity and Competition on Root Architecture of Spruce Seedlings: Implications for an Essential Feature of Root Foraging

    OpenAIRE

    Nan, Hongwei; Liu, Qing; Chen, Jinsong; Cheng, Xinying; Yin, Huajun; Yin, Chunying; Zhao, Chunzhang

    2013-01-01

    Background We have limited understanding of root foraging responses when plants were simultaneously exposed to nutrient heterogeneity and competition, and our goal was to determine whether and how plants integrate information about nutrients and neighbors in root foraging processes. Methodology/Principal Findings The experiment was conducted in split-containers, wherein half of the roots of spruce (Picea asperata) seedlings were subjected to intraspecific root competition (the vegetated half)...

  14. The effect of small- and core-scale heterogeneity on the multiphase flow properties of CO2 and water in sandstones

    Science.gov (United States)

    Pini, R.; Benson, S. M.

    2012-12-01

    Capillary pressure and relative permeability functions are characteristic curves that, when coupled to the continuum-scale equations of motion, allow for a description of multiphase displacement processes in porous media. Traditionally, these properties are measured in the laboratory and are implemented into reservoir simulations to predict the behavior at the field-scale. There is an increasing awareness that detailed investigations are required to understand the role of the inherent heterogeneity of the rock samples used in the experiments on the measured multiphase properties. In fact, although a significant amount of simulation work has explored the effect of heterogeneities on Pc-kr-S relationships, very few experimental studies report on displacements with well-characterized, naturally heterogeneous media. To extend the current data set and to support these numerical findings, more laboratory data are therefore required that have been obtained under a variety of conditions and on cores from different geological settings. A direct practical implication of these studies would be the definition of a minimum scale at which heterogeneities have to be resolved, so that mathematical models would adequately capture the observed displacement patterns. Moreover, the coupling of experiments and theory will serve as a firm starting point for testing scale-up methods. In this study, results from core-flooding experiments are presented that have been carried out at representative conditions on a variety of naturally heterogeneous core samples. Results are presented from a newly developed technique that allows measuring drainage capillary pressure curves during core-flooding experiments; data have been collected at different temperature (25 and 50C), at different pressures (2 and 9MPa) and with different fluid pairs (CO2/water, N2/water and CO2/brine), thus showing the applicability of the novel technique in a wide range of interfacial tension levels. Additionally, Pc

  15. Aggregation on heterogeneous surface

    Institute of Scientific and Technical Information of China (English)

    Lu Hang-Jun; Wu Feng-Min; Fang Yun-Zhang

    2004-01-01

    Chessboard-like substrates are introduced in this paper, in order to study the diffusion-limited aggregation (DLA)and the motion of poly-atoms on heterogeneous surfaces. The effect of morphology of such substrates upon the cluster aggregation is investigated using the Monte Carlo simulation. It is found that the growth process and the cluster morphology are governed by the energetic topography of the substrates. Our simulation also indicate that the island density and the fractal dimension of the clusters depend strongly on the substrate topography and the activation energy.

  16. Fast Nongenomic Effect of Aldosterone on the Volume of Principal Cells in Collecting Tube and Genetic Heterogeneity of Epithelial Sodium Channel in the Postnatal Ontogenesis of Rat Kidney.

    Science.gov (United States)

    Logvinenko, N S; Gerbek, Yu E; Solenov, E I; Ivanova, L N

    2016-03-01

    The effects of amiloride, epithelial sodium pump inhibitor, on the fast nongenomic effect of aldosterone in principal cells of an isolated segment of the distal portion of renal collecting tubes were studied in 10-day-old and adult rats. Fluorescent staining with Calcein AM showed various effects of amiloride (10(-5) M) on the stabilizing effect of aldosterone (10 nM) in hypotonic shock (280/140 mOsm/kg). Amiloride attenuated by 30% the effect of aldosterone on the amplitude of principal cell swelling in adult animals and almost completely abolished this effect in 10-day rats (p<0.05). These age-specific differences in the contribution of the distal portion of the collecting tube to the nongenomic effect of aldosterone did not depend on genetic heterogeneity of its α-subunit. PMID:27021081

  17. SU-E-J-94: Positioning Errors Resulting From Using Bony Anatomy Alignment for Treating SBRT Lung Tumor

    International Nuclear Information System (INIS)

    Purpose: To quantify patient setups errors based on bony anatomy registration rather than 3D tumor alignment for SBRT lung treatments. Method: A retrospective study was performed for patients treated with lung SBRT and imaged with kV cone beam computed tomography (kV-CBCT) image-guidance. Daily CBCT images were registered to treatment planning CTs based on bony anatomy alignment and then inter-fraction tumor movement was evaluated by comparing shift in the tumor center in the medial-lateral, anterior-posterior, and superior-inferior directions. The PTV V100% was evaluated for each patient based on the average daily tumor displacement to assess the impact of the positioning error on the target coverage when the registrations were based on bony anatomy. Of the 35 patients studied, 15 were free-breathing treatments, 10 used abdominal compression with a stereotactic body frame, and the remaining 10 were performed with BodyFIX vacuum bags. Results: For free-breathing treatments, the range of tumor displacement error is between 1–6 mm in the medial-lateral, 1–13 mm in the anterior-posterior, and 1–7 mm in the superior-inferior directions. These positioning errors lead to 6–22% underdose coverage for PTV - V100% . Patients treated with abdominal compression immobilization showed positional errors of 0–4mm mediallaterally, 0–3mm anterior-posteriorly, and 0–2 mm inferior-superiorly with PTV - V100% underdose ranging between 6–17%. For patients immobilized with the vacuum bags, the positional errors were found to be 0–1 mm medial-laterally, 0–1mm anterior-posteriorly, and 0–2 mm inferior-superiorly with PTV - V100% under dose ranging between 5–6% only. Conclusion: It is necessary to align the tumor target by using 3D image guidance to ensure adequate tumor coverage before performing SBRT lung treatments. The BodyFIX vacuum bag immobilization method has the least positioning errors among the three methods studied when bony anatomy is used for

  18. SU-E-J-33: Comparison Between Soft Tissue Alignment and Bony Alignment for Pancreatic Cancer Radiotherapy

    International Nuclear Information System (INIS)

    Purpose An IGRT modality for pancreatic cancer treatment with dose escalation at our institution is in-room daily CT imaging. The purpose of this study is to assess the difference between soft tissue alignment and bony alignment for pancreatic tumor localization. Methods Eighteen patients with pancreatic tumors who underwent IMRT treatment with an inspiration breath-hold technique between July 2012 and February 2015 are included in this study. Prior to each treatment, a CT scan was acquired. The CT image guidance started with auto-alignment to either the bony anatomy (vertebral bodies) or fiducials (for the six patients with the stent in/near the tumor) and then, when necessary, manual adjustments were made based on soft tissue alignment using clinical software (CT-Assisted Targeting system). The difference between soft tissue alignment and bony/fiducial alignment was evaluated. Results Of all 380 treatments, manual adjustment was made in 225 treatments, ranging from 11% (3 treatments out of 28) to 96% (27 treatments out of 28) per patient. The mean of the difference between soft tissue alignment and bony/fiducial alignment per patient ranged from −3.6 to 0.3 mm, −1.5 to 2.8 mm, and −3.3 to 3.4 mm in the AP, SI, and RL directions, respectively. The maximum difference over all treatments was −9.5, −14.6, and −14.6 mm in the AP, SI, and RL directions, respectively. Conclusion About 60% of the time, manual adjustment based on soft tissue alignment was required. The extent of manual adjustment was usually small but varied significantly from patient to patient. The ultimate goal of the IGRT modality using daily CT imaging is not to fully cover the target but to spare organs-at-risk as much as possible to avoid them moving into higher dose gradients than accepted in the treatment plan. To this end, manual adjustment based on soft tissue alignment is critically important

  19. SU-E-J-33: Comparison Between Soft Tissue Alignment and Bony Alignment for Pancreatic Cancer Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Y; Crane, C; Krishnan, S; Das, P; Koay, E; Beddar, S [UT MD Anderson Cancer Center, Houston, TX (United States)

    2015-06-15

    Purpose An IGRT modality for pancreatic cancer treatment with dose escalation at our institution is in-room daily CT imaging. The purpose of this study is to assess the difference between soft tissue alignment and bony alignment for pancreatic tumor localization. Methods Eighteen patients with pancreatic tumors who underwent IMRT treatment with an inspiration breath-hold technique between July 2012 and February 2015 are included in this study. Prior to each treatment, a CT scan was acquired. The CT image guidance started with auto-alignment to either the bony anatomy (vertebral bodies) or fiducials (for the six patients with the stent in/near the tumor) and then, when necessary, manual adjustments were made based on soft tissue alignment using clinical software (CT-Assisted Targeting system). The difference between soft tissue alignment and bony/fiducial alignment was evaluated. Results Of all 380 treatments, manual adjustment was made in 225 treatments, ranging from 11% (3 treatments out of 28) to 96% (27 treatments out of 28) per patient. The mean of the difference between soft tissue alignment and bony/fiducial alignment per patient ranged from −3.6 to 0.3 mm, −1.5 to 2.8 mm, and −3.3 to 3.4 mm in the AP, SI, and RL directions, respectively. The maximum difference over all treatments was −9.5, −14.6, and −14.6 mm in the AP, SI, and RL directions, respectively. Conclusion About 60% of the time, manual adjustment based on soft tissue alignment was required. The extent of manual adjustment was usually small but varied significantly from patient to patient. The ultimate goal of the IGRT modality using daily CT imaging is not to fully cover the target but to spare organs-at-risk as much as possible to avoid them moving into higher dose gradients than accepted in the treatment plan. To this end, manual adjustment based on soft tissue alignment is critically important.

  20. Heterogeneity in Preferences and Productivity

    DEFF Research Database (Denmark)

    Gørtz, Mette

    -section data, we can identify a difference in consumption due to retirement status, but when the panel nature of the data is exploited, the effect of retirement on consumption is small and insignificant. Moreover, the analyses point at a large positive effect of retirement on household production. Our results......This paper discusses the determinants of the retirement decision and the implications of retirement on economic well-being. The main contribution of the paper is to formulate the role of individual heterogeneity explicitly. We argue that individual heterogeneity in 1) productivity of market work...... choices of expenditure, household production and leisure for people in and around retirement. The unobserved individual heterogeneity factor is isolated by comparing cross-sectional evidence and panel data estimates of the effects of retirement on consumption and time allocation. Based on cross...

  1. Rapid effect of heat shock on two heterogeneous nuclear ribonucleoprotein-associated antigens in HeLa cells

    OpenAIRE

    1989-01-01

    During severe heat shock, which known to interrupt both splicing of RNA transcripts and nucleocytoplasmic transport, it is to be expected that the substructure of heterogeneous nuclear ribonucleoproteins (hnRNP) is altered in some way. Recently, we have shown that such a stress actually induces rapid alterations at the level of individual proteins (Lutz, Y., M. Jacob, and J.-P. Fuchs. 1988 Exp. Cell Res. 175:109-124). Here we report further investigations on two related 72.5-74-kD hnRNP prote...

  2. Bony outgrowths on the jaws of an extinct sperm whale support macroraptorial feeding in several stem physeteroids

    Science.gov (United States)

    Lambert, Olivier; Bianucci, Giovanni; Beatty, Brian L.

    2014-06-01

    Several extinct sperm whales (stem Physeteroidea) were recently proposed to differ markedly in their feeding ecology from the suction-feeding modern sperm whales Kogia and Physeter. Based on cranial, mandibular, and dental morphology, these Miocene forms were tentatively identified as macroraptorial feeders, able to consume proportionally large prey using their massive teeth and robust jaws. However, until now, no corroborating evidence for the use of teeth during predation was available. We report on a new specimen of the stem physeteroid Acrophyseter, from the late middle to early late Miocene of Peru, displaying unusual bony outgrowths along some of the upper alveoli. Considering their position and outer shape, these are identified as buccal maxillary exostoses. More developed along posterior teeth and in tight contact with the high portion of the dental root outside the bony alveoli, the exostoses are hypothesized to have developed during powerful bites; they may have worked as buttresses, strengthening the teeth when facing intense occlusal forces. These buccal exostoses further support a raptorial feeding technique for Acrophyseter and, indirectly, for other extinct sperm whales with a similar oral apparatus ( Brygmophyseter, Livyatan, Zygophyseter). With a wide size range, these Miocene stem physeteroids were major marine macropredators, occupying ecological niches nowadays mostly taken by killer whales.

  3. Bony pathologies of the metacarpophalangeal joints in early rheumatoid arthritis. Comparison of MRI and high-resolution SPECT

    International Nuclear Information System (INIS)

    Aim: comparison of MRI with a newly developed high-resolution multi-pinhole single photon emission computed tomography (MPH-SPECT) regarding the detection of bony pathologies of the metacarpophalangeal (MCP) joints in patients with early rheumatoid arthritis (ERA). Materials and methods: the clinically dominant hand of 15 patients with ERA (disease duration 6 months) was examined using MRI and MPH-SPECT. The evaluation of MRI was achieved according to RAMRIS criteria and for the MPH SPECT regarding pathological tracer uptake and distribution. Image fusions of MRI and MPH-SPECT were provided and the two methods were compared. Results: in MRI 12 of 15 patients showed arthritic joint pathologies, while 8 patients exhibited soft tissue and bony changes. 4 patients had only soft tissue inflammation (synovitis) with a normal bone signal. In MPH-SPECT 10 of 15 patients showed pathologically increased bone metabolism. The fusion images presented a high agreement of the pathological changes in both methods, while areas with increased bone metabolism were not only present in the case of erosions, but also in the case of bone edema. In 2 patients increased bone metabolism was detectable in areas of MR tomographic normal bone, while a clear surrounding synovitis was present in each case here. (orig.)

  4. A dose-response relationship for time to bone pain resolution after stereotactic body radiotherapy (SBRT) for renal cell carcinoma (RCC) bony metastases

    International Nuclear Information System (INIS)

    Background. To investigate the utility of stereotactic body radiotherapy (SBRT) in the treatment of painful renal cell carcinoma (RCC) bone metastases, and for a possible dose effect on time to symptom relief. Material and methods. Eighteen patients with 24 painful osseous lesions from metastatic RCC were treated with SBRT. The most common treatment regimens were 24 Gy in 3 fractions and 40 Gy in 5 fractions. The times from treatment to first reported pain relief and time to symptom recurrence were evaluated. Median follow-up was 38 weeks (1-156 weeks). Results. Seventy-eight percent of all patients had pain relief. Patients treated with a BED > 85 Gy achieved faster and more durable pain relief compared to those treated with a BED < 85 Gy. There was decrease in time to pain relief after a change in treatment regimen to 8 Gy x 5 fractions (BED = 86). There was only one patient with grade 1 skin toxicity. No neurological or other toxicity was observed. Conclusions. SBRT can safely and effectively treat painful RCC bony metastases. There appears to be a relationship between radiation dose and time to stable pain relief

  5. A dose-response relationship for time to bone pain resolution after stereotactic body radiotherapy (SBRT) for renal cell carcinoma (RCC) bony metastases

    Energy Technology Data Exchange (ETDEWEB)

    Jhaveri, Pavan M. [Dept. of Radiology, Section of Radiation Oncology, Baylor College of Medicine, Houston (United States); Teh, Bin S.; Paulino, Arnold C.; Blanco, Angel I.; Butler, E. Brian [Dept. of Radiation Oncology, The Methodist Hospital/The Methodist Hospital Research Inst., Houston (United States)], email: bteh@tmhs.org; Lo, Simon S. [Dept. of Radiation Oncology, Univ. Hospitals Seidman Cancer Center, Case Western Reserve Univ., Cleveland (United States); Amato, Robert J. [Dept. of Internal Medicine, Div. of Oncology, Univ. of Texas Health Sciences Center, Houston (United States)

    2012-05-15

    Background. To investigate the utility of stereotactic body radiotherapy (SBRT) in the treatment of painful renal cell carcinoma (RCC) bone metastases, and for a possible dose effect on time to symptom relief. Material and methods. Eighteen patients with 24 painful osseous lesions from metastatic RCC were treated with SBRT. The most common treatment regimens were 24 Gy in 3 fractions and 40 Gy in 5 fractions. The times from treatment to first reported pain relief and time to symptom recurrence were evaluated. Median follow-up was 38 weeks (1-156 weeks). Results. Seventy-eight percent of all patients had pain relief. Patients treated with a BED > 85 Gy achieved faster and more durable pain relief compared to those treated with a BED < 85 Gy. There was decrease in time to pain relief after a change in treatment regimen to 8 Gy x 5 fractions (BED = 86). There was only one patient with grade 1 skin toxicity. No neurological or other toxicity was observed. Conclusions. SBRT can safely and effectively treat painful RCC bony metastases. There appears to be a relationship between radiation dose and time to stable pain relief.

  6. Preparative treatment with NaOH to selectively concentrate iron oxides of a Chilean volcanic soil material to produce effective heterogeneous Fenton catalyst

    International Nuclear Information System (INIS)

    A Chilean volcanic Ultisol material was first size-fractionated so as to obtain the fraction with mean particle sizes φ  − 1 NaOH, in an attempt to evaluate the effectiveness of the selective chemical dissolution to concentrate iron oxides, as a preparation procedure before using the materials as heterogeneous Fenton catalysts. The effects of those treatments on the iron oxides mineralogy were monitored with Mössbauer spectroscopy. The NaOH-treated samples were tested as catalysts towards the H2O2 decomposition. Three or five sequential NaOH treatments were found to be comparably effective, by concentrating nearly the same proportion of iron oxides in the remaining solid phase (25.1 ± 0.4 and 23.3 ± 0.2 mass%, respectively). 298 K-Mössbauer patterns were similar for both samples, with a central (super)paramagnetic Fe3 +  doublet and a broad sextet, assignable to several closely coexisting magnetically ordered forms of iron oxides. Despite of this nearly similar effect of the two treatments, the Ultisol material treated three times with NaOH presents higher heterogeneous catalytic efficiency and is more suitable to decompose H2O2 than that with five treatments.

  7. Isolating effects of terrain and soil moisture heterogeneity on the atmospheric boundary layer: Idealized simulations to diagnose land-atmosphere feedbacks

    Science.gov (United States)

    Rihani, Jehan F.; Chow, Fotini K.; Maxwell, Reed M.

    2015-06-01

    The effects of terrain, soil moisture heterogeneity, subsurface properties, and water table dynamics on the development and behavior of the atmospheric boundary layer are studied through a set of idealized numerical experiments. The mesoscale atmospheric model Advanced Regional Prediction System (ARPS) is used to isolate the effects of subsurface heterogeneity, terrain, and soil moisture initialization. The simulations are initialized with detailed soil moisture distributions obtained from offline spin-ups using a coupled surface-subsurface model (ParFlow-CLM). In these idealized simulations, we observe that terrain effects dominate the planetary boundary layer (PBL) development during early morning hours, while the soil moisture signature overcomes that of terrain during the afternoon. Water table and subsurface properties produce a similar effect as that of soil moisture as their signatures (reflected in soil moisture profiles, energy fluxes, and evaporation at the land surface) can also overcome that of terrain during afternoon hours. This is mostly clear for land surface energy fluxes and evaporation at the land surface. We also observe the coupling between water table depth and planetary boundary layer depth in our cases is strongest within wet-to-dry transition zones. This extends the findings of previous studies which demonstrate the subsurface connection to surface energy fluxes is strongest in such transition zones. We investigate how this connection extends into the atmosphere and can affect the structure and development of the convective boundary layer.

  8. Effect of non-acoustic parameters on heterogeneous sonoporation mediated by single-pulse ultrasound and microbubbles.

    Science.gov (United States)

    Qin, Peng; Xu, Lin; Han, Tao; Du, Lianfang; Yu, Alfred C H

    2016-07-01

    Sonoporation-transient plasma membrane perforation elicited by the interaction of ultrasound waves with microbubbles-has shown great potential for drug delivery and gene therapy. However, the heterogeneity of sonoporation introduces complexities and challenges in the realization of controllable and predictable drug delivery. The aim of this investigation was to understand how non-acoustic parameters (bubble related and bubble-cell interaction parameters) affect sonoporation. Using a customized ultrasound-exposure and fluorescence-imaging platform, we observed sonoporation dynamics at the single-cell level and quantified exogenous molecular uptake levels to characterize the degree of sonoporation. Sonovue microbubbles were introduced to passively regulate microbubble-to-cell distance and number, and bubble size. 1MHz ultrasound with 10-cycle pulse duration and 0.6MPa peak negative pressure were applied to trigger the inertial collapse of microbubbles. Our data revealed the impact of non-acoustic parameters on the heterogeneity of sonoporation. (i) The localized collapse of relatively small bubbles (diameter, D1, whereas reversible sonoporation occurred when d/D5.5μm) exhibited translational movement over large distances, resulting in unpredictable sonoporation. Translation towards the cell surface led to variable reversible sonoporation or irreversible sonoporation, and translation away from the cell caused either no or reversible sonoporation. (iii) The number of bubbles correlated positively with the degree of sonoporation when Dacoustic parameters and the degree of sonoporation. PMID:26964929

  9. Effects of grain size and structural heterogeneity on the transport and retention of nano-TiO2 in saturated porous media.

    Science.gov (United States)

    Lv, Xueyan; Gao, Bin; Sun, Yuanyuan; Dong, Shunan; Wu, Jichun; Jiang, Beilei; Shi, Xiaoqing

    2016-09-01

    Accurately predicting the fate and transport of nano-TiO2 in porous media is critical to assess its environmental impact. This study was designed to understand the effects of gain size and structural heterogeneity under different ionic strength (IS) on the fate and transport of nano-TiO2 in saturated porous media. In the columns packed homogenously with sand of different grain sizes (920, 550, 390, and 275μm), the transport of nano-TiO2 decreased when the IS increased from 0.1 to 1 or 10mM. For all the three IS conditions, the retention of the nano-TiO2 particles in the columns increased when the gain size decreased, and the mobility of the nano-TiO2 was the lowest in the sand at size of 275μm with recovery rates of 0.30% to 1.72%. The mass recovery rates of TiO2 in other homogeneous columns were higher and ranged from 0.37% to 59.9%. Structural heterogeneity created two flow domains for the retention and transport of nano-TiO2 particles in the saturated porous media. The fast-flow domain dominated the flow and transport processes of the nano-TiO2 in the heterogeneous columns under the tested conditions. As a result, the transport of nano-TiO2 in the heterogeneous porous media was faster and higher than that in the homogeneous columns under similar experimental conditions. Because of the dominance of the fast-flow domain, the recovery rates of the nano-TiO2 in the heterogeneous columns were similar and ranged from 59.8% to 66.9%. These results reflected the importance of preferential flow to the fate and transport of nano-TiO2 particle in porous media. Simulations from a two-domain model matched the experimental breakthrough curves very well. PMID:26774131

  10. The Effects of Fine-scale Soil Moisture and Canopy Heterogeneities on Energy and Soil Water Fluxes in a Temperate Mixed Deciduous Forest

    Science.gov (United States)

    He, L.; Ivanov, V. Y.; Bohrer, G.; Maurer, K.; Vogel, C. S.; Moghaddam, M.

    2011-12-01

    Vegetation is heterogeneous at different scales, influencing spatially variable energy and water exchanges between land-surface and atmosphere. Current land surface parameterizations of large-scale models consider spatial variability at a scale of a few kilometers and treat vegetation cover as aggregated patches with uniform properties. However, the coupling mechanisms between fine-scale soil moisture, vegetation, and energy fluxes such as evapotranspiration are strongly nonlinear; the aggregation of surface variations may produce biased energy fluxes. This study aims to improve the understanding of the scale impact in atmosphere-biosphere-hydrosphere interactions, which affects predictive capabilities of land surface models. The study uses a high-resolution, physically-based ecohydrological model tRIBS + VEGGIE as a data integration tool to upscale the heterogeneity of canopy distribution resolved at a few meters to the watershed scale. The study was carried out for a spatially heterogeneous, temperate mixed forest environment of Northern Michigan located near the University of Michigan Biological Station (UMBS). Energy and soil water dynamics were simulated at the tree-canopy resolution in the horizontal plane for a small domain (~2 sq. km) located within a footprint of the AmeriFlux tower. A variety of observational data were used to constrain and confirm the model, including a 3-m profile continuous soil moisture dataset and energy flux data (measured at the AmeriFlux tower footprint). A scenario with a spatially uniform canopy, corresponding to the commonly used 'big-leaf' scheme in land surface parameterizations was used to infer the effects of coarse-scale averaging. To gain insights on how heterogeneous canopy and soil moisture interact and contribute to the domain-averaged transpiration, several scenarios of tree-scale leaf area and soil moisture spatial variability were designed. Specifically, for the same mean states, the scenarios of variability of

  11. A time series study on the effects of heat on mortality and evaluation of heterogeneity into European and Eastern-Southern Mediterranean cities: results of EU CIRCE project

    OpenAIRE

    Dörbudak, Zeynep; Leone, Michela; D'Ippoliti, Daniela; De Sario, Manuela; Analitis, Antonis; Menne, Bettina; Katsouyanni, Klea; de'Donato, Francesca K.; Basagana, Xavier; Ben Salah, Afif; Casimiro, Elsa; Iniguez, Carmen; Peretz, Chava; Wolf, Tanja; Michelozzi, Paola

    2013-01-01

    RESEARCH Open Access A time series study on the effects of heat on mortality and evaluation of heterogeneity into European and Eastern-Southern Mediterranean cities: results of EU CIRCE project Michela Leone1*, Daniela D’Ippoliti1, Manuela De Sario1, Antonis Analitis2, Bettina Menne3, Klea Katsouyanni2, Francesca K de’ Donato1, Xavier Basagana4,5,6, Afif Ben Salah7, Elsa Casimiro8, Zeynep Dörtbudak9, Carmen Iñiguez4,10,11, Chava Peretz12, Tanja Wolf3 and Paola Michelozzi1...

  12. Heterogeneous Materials I and Heterogeneous Materials II

    International Nuclear Information System (INIS)

    In these two volumes the author provides a comprehensive survey of the various mathematically-based models used in the research literature to predict the mechanical, thermal and electrical properties of hetereogeneous materials, i.e., materials containing two or more phases such as fibre-reinforced polymers, cast iron and porous ceramic kiln furniture. Volume I covers linear properties such as linear dielectric constant, effective electrical conductivity and elastic moduli, while Volume II covers nonlinear properties, fracture and atomistic and multiscale modelling. Where appropriate, particular attention is paid to the use of fractal geometry and percolation theory in describing the structure and properties of these materials. The books are advanced level texts reflecting the research interests of the author which will be of significant interest to research scientists working at the forefront of the areas covered by the books. Others working more generally in the field of materials science interested in comparing predictions of properties with experimental results may well find the mathematical level quite daunting initially, as it is apparent that the author assumes a level of mathematics consistent with that taught in final year undergraduate and graduate theoretical physics courses. However, for such readers it is well worth persevering because of the in-depth coverage to which the various models are subjected, and also because of the extensive reference lists at the back of both volumes which direct readers to the various source references in the scientific literature. Thus, for the wider materials science scientific community the two volumes will be a valuable library resource. While I would have liked to see more comparison with experimental data on both ideal and 'real' heterogeneous materials than is provided by the author and a discussion of how to model strong nonlinear current--voltage behaviour in systems such as zinc oxide varistors, my overall

  13. Demographic heterogeneity, cohort selection, and population growth

    OpenAIRE

    Kendall, Bruce E.; Fox, Gordon A; Fujiwara, Masami; Nogeire, Theresa M.

    2011-01-01

    Demographic heterogeneity—variation among individuals in survival and reproduction—is ubiquitous in natural populations. Structured population models address heterogeneity due to age, size, or major developmental stages. However, other important sources of demographic heterogeneity, such as genetic variation, spatial heterogeneity in the environment, maternal effects, and differential exposure to stressors, are often not easily measured and hence are modeled as stochasticity. Recent research ...

  14. Influence of rotational setup error on tumor shift in bony anatomy matching measured with pulmonary point registration in stereotactic body radiotherapy for early lung cancer

    International Nuclear Information System (INIS)

    The objective of this study was to examine the correlation between the patient rotational error measured with pulmonary point registration and tumor shift after bony anatomy matching in stereotactic body radiotherapy for lung cancer. Twenty-six patients with lung cancer who underwent stereotactic body radiotherapy were the subjects. On 104 cone-beam computed tomography measurements performed prior to radiation delivery, rotational setup errors were measured with point registration using pulmonary structures. Translational registration using bony anatomy matching was done and the three-dimensional vector of tumor displacement was measured retrospectively. Correlation among the three-dimensional vector and rotational error and vertebra-tumor distance was investigated quantitatively. The median and maximum rotational errors of the roll, pitch and yaw were 0.8, 0.9 and 0.5, and 6.0, 4.5 and 2.5, respectively. Bony anatomy matching resulted in a 0.2-1.6 cm three-dimensional vector of tumor shift. The shift became larger as the vertebra-tumor distance increased. Multiple regression analysis for the three-dimensional vector indicated that in the case of bony anatomy matching, tumor shifts of 5 and 10 mm were expected for vertebra-tumor distances of 4.46 and 14.1 cm, respectively. Using pulmonary point registration, it was found that the rotational setup error influences the tumor shift. Bony anatomy matching is not appropriate for hypofractionated stereotactic body radiotherapy with a tight margin. (author)

  15. Synergetic Effect of Ultrasound, the Heterogeneous Fenton Reaction and Photocatalysis by TiO2 Loaded on Nickel Foam on the Degradation of Pollutants

    Directory of Open Access Journals (Sweden)

    Shan Qiu

    2016-06-01

    Full Text Available The synergistic effect of ultrasound, the heterogeneous Fenton reaction and photocatalysis was studied using a nickel foam (NF-supporting TiO2 system and rhodamine B (RhB as a target. The NF-supporting TiO2 system was prepared by depositing TiO2 on the skeleton of NF repeatedly and then calcining it. To optimize the conditions and parameters, the catalytic activity was tested in four systems (ultrasound alone (US, nickel foam (NF, US/NF and NF/US/H2O2. The optimal conditions were fixed at 0.1 g/mL NF, initial 5.00 mg/L RhB, 300 W ultrasonic power, pH = 3 and 5.00 mg/L H2O2. The effects of the dissolution of nickel from NF and quenching of the Fenton reaction were studied on degradation efficiency. When the heterogeneous Fenton reaction is combined with TiO2-photocatalysis, the pollutant removal efficiency is enhanced significantly. Through this synergistic effect, 22% and 80% acetochlor was degraded within 10 min and 80 min, respectively.

  16. Evaluation of material heterogeneity dosimetric effects using radiochromic film for COMS eye plaques loaded with {sup 125}I seeds (model I25.S16)

    Energy Technology Data Exchange (ETDEWEB)

    Acar, Hilal; Chiu-Tsao, Sou-Tung; Oezbay, Ismail; Kemikler, Goenuel; Tuncer, Samuray [Istanbul University Medicine Faculty, Oncology Institute, Fatih, Istanbul 34093 (Turkey); Quality MediPhys LLC, 17 Jade Lane, Denville, New Jersey 07834 (United States); Istanbul University Medicine Faculty, Oncology Institute, Fatih, Istanbul 34093 (Turkey); Istanbul University Medicine Faculty, Eye Department, Fatih, Istanbul 34093 (Turkey)

    2013-01-15

    .8 and 0.9) for all four plaque sizes, indicating dose reduction by COMS plaque compared with homogeneous assumption. The dose ratio (film/PS Hetero) values were close to unity, indicating the PS Hetero calculations agree with those from the film study. Conclusions: Substantial heterogeneity effect on the {sup 125}I dose distributions in an eye phantom for COMS plaques was verified using radiochromic EBT film dosimetry. The calculated doses for uniformly loaded plaques using PS with heterogeneity correction option enabled were corroborated by the EBT film measurement data. Radiochromic EBT film dosimetry is feasible in measuring absolute dose distributions in eye phantom for COMS eye plaques loaded with single or multiple {sup 125}I seeds. Plaque Simulator is a viable tool for the calculation of dose distributions if one understands its limitations and uses the proper heterogeneity correction feature.

  17. Evaluation of material heterogeneity dosimetric effects using radiochromic film for COMS eye plaques loaded with 125I seeds (model I25.S16)

    International Nuclear Information System (INIS)

    plaque sizes, indicating dose reduction by COMS plaque compared with homogeneous assumption. The dose ratio (film/PS Hetero) values were close to unity, indicating the PS Hetero calculations agree with those from the film study. Conclusions: Substantial heterogeneity effect on the 125I dose distributions in an eye phantom for COMS plaques was verified using radiochromic EBT film dosimetry. The calculated doses for uniformly loaded plaques using PS with heterogeneity correction option enabled were corroborated by the EBT film measurement data. Radiochromic EBT film dosimetry is feasible in measuring absolute dose distributions in eye phantom for COMS eye plaques loaded with single or multiple 125I seeds. Plaque Simulator is a viable tool for the calculation of dose distributions if one understands its limitations and uses the proper heterogeneity correction feature.

  18. Effects of compositional heterogeneity and nanoporosity of raw and treated biomass-generated soot on adsorption and absorption of organic contaminants

    International Nuclear Information System (INIS)

    A biomass-generated soot was sequentially treated by HCl-HF solution, organic solvent, and oxidative acid to remove ash, extractable native organic matter (EOM), and amorphous carbon. The compositional heterogeneity and nano-structure of the untreated and treated soot samples were characterized by elemental analysis, thermal gravimetric analysis, BET-N2 surface area, and electron microscopic analysis. Sorption properties of polar and nonpolar organic pollutants onto the soot samples were compared, and individual contributions of adsorption and absorption were quantified. The sorption isotherms for raw sample were practically linear, while were nonlinear for the pretreated-soot. The removal of EOM enhanced adsorption and reduced absorption, indicating that EOM served as a partitioning phase and simultaneously masked the adsorptive sites. By drastic-oxidation, the outer amorphous carbon and the inner disordered core of the soot particles were completely removed, and a fullerene-like nanoporous structure (aromatic shell) was created, which promoted additional π-π interaction between phenanthrene and the soot. - Graphical abstract: The dual sorptive nature of the biomass-generated soot, i.e., the adsorptive effect of the carbonized soot fraction and the partition effect of the amorphous soot component. Research highlights: → The biomass-generated soot owns the heterogeneous compositions and nano-structures. → The soot exhibits the dual sorptive nature, i.e., adsorption and absorption. → Removal of the amorphous component weakens absorption, but strengthens adsorption. → The exposed adsorptive sites with highly aromatic nature promotes π-π interaction. → The dual sorptive nature of the soot depends on the various soot components. - The compositional heterogeneity and nano-structure play a regulating role in the adsorption and absorption of organic contaminants with the untreated and treated soot samples.

  19. Laboratory investigations of the effects of geologic heterogeneity on groundwater salinization and flush-out times from a tsunami-like event

    Science.gov (United States)

    Vithanage, M.; Engesgaard, P.; Jensen, K. H.; Illangasekare, T. H.; Obeysekera, J.

    2012-08-01

    This intermediate scale laboratory experimental study was designed to improve the conceptual understanding of aquifer flushing time associated with diffuse saltwater contamination of coastal aquifers due to a tsunami-like event. The motivation comes from field observations made after the tsunami in December, 2004 in South Asia. The focus is on the role and effects of heterogeneity on flushing effectiveness. A scheme that combines experimentation in a 4.8 m long laboratory tank and numerical modeling was used. To demonstrate the effects of geologic heterogeneity, plume migration and flushing times were analyzed in both homogeneous and layered media and under different boundary conditions (ambient flow, saltwater infiltration rate, freshwater recharge). Saltwater and freshwater infiltrations imitate the results of the groundwater salinization from the tsunami and freshening from the monsoon rainfall. The saltwater plume behavior was monitored both through visual observations (digital photography) of the dyed salt water and using measurements taken from several electrical conductivity sensors installed through the tank walls. The variable-density, three dimensional code HST3D was used to simulate the tank experiments and understand the fate and movement of the saltwater plume under field conditions. The results from the tank experiments and modeling demonstrated that macro-scale heterogeneity significantly influenced the migration patterns and flushing times of diffuse saltwater contamination. Ambient flow had a direct influence on total flush-out time, and heterogeneity impacted flush-out times for the top part of the tank and total flush-out times. The presence of a continuous low-permeability layer caused a 40% increase in complete flush-out time due to the slower flow of salt water in the low-permeability layer. When a relatively small opening was introduced in the low-permeability layer, salt water migrated quickly into a higher-permeable layer below causing a

  20. Genomic Characterization of High-Grade Serous Ovarian Cancer: Dissecting Its Molecular Heterogeneity as a Road Towards Effective Therapeutic Strategies.

    Science.gov (United States)

    Mittempergher, Lorenza

    2016-07-01

    High-grade serous ovarian carcinoma (HGSOC) accounts for the majority of the ovarian cancer deaths, but over the last years little improvement in overall survival has been achieved. HGSOC is a molecularly and clinically heterogeneous disease. At genomic level, it represents a C-class malignancy having frequent gene losses (NF1, RB1, PTEN) and gains (CCNE1, MYC). HGSOC shows a simple mutational profile with TP53 nearly always mutated and with other genes mutated at low frequency. Importantly, 50 % of all HGSOCs have genetic features indicating a homologous recombination (HR) deficiency. HR deficient tumors are highly sensitive to PARP inhibitor anticancer agents, which exhibit synthetic lethality with a defective HR pathway. Transcriptionally, HGSOCs can be grouped into different molecular subtypes with distinct biology and prognosis. Molecular stratification of HGSOC based on these genomic features may result in improved therapeutic strategies. PMID:27241520

  1. Local cascades induced global contagion: How heterogeneous thresholds, exogenous effects, and unconcerned behaviour govern online adoption spreading

    CERN Document Server

    Karsai, Márton; Kikas, Riivo; Kaski, Kimmo; Kertész, János

    2016-01-01

    Adoption of innovations, products or online services is commonly interpreted as a spreading process driven to large extent by social influence and conditioned by the needs and capacities of individuals. To model this process one usually introduces behavioural threshold mechanisms, which can give rise to the evolution of global cascades if the system satisfies a set of conditions. However, these models do not address temporal aspects of the emerging cascades, which in real systems may evolve through various pathways ranging from slow to rapid patterns. Here we fill this gap through the analysis and modelling of product adoption in the world's largest voice over internet service, the social network of Skype. We provide empirical evidence about the heterogeneous distribution of fractional behavioural thresholds, which appears to be independent of the degree of adopting egos. We show that the structure of real-world adoption clusters is radically different from previous theoretical expectations, since vulnerable ...

  2. Effect of methodological and ecological approaches on heterogeneity of nest-site selection of a long-lived vulture.

    Directory of Open Access Journals (Sweden)

    Rubén Moreno-Opo

    Full Text Available The application of scientific-based conservation measures requires that sampling methodologies in studies modelling similar ecological aspects produce comparable results making easier their interpretation. We aimed to show how the choice of different methodological and ecological approaches can affect conclusions in nest-site selection studies along different Palearctic meta-populations of an indicator species. First, a multivariate analysis of the variables affecting nest-site selection in a breeding colony of cinereous vulture (Aegypius monachus in central Spain was performed. Then, a meta-analysis was applied to establish how methodological and habitat-type factors determine differences and similarities in the results obtained by previous studies that have modelled the forest breeding habitat of the species. Our results revealed patterns in nesting-habitat modelling by the cinereous vulture throughout its whole range: steep and south-facing slopes, great cover of large trees and distance to human activities were generally selected. The ratio and situation of the studied plots (nests/random, the use of plots vs. polygons as sampling units and the number of years of data set determined the variability explained by the model. Moreover, a greater size of the breeding colony implied that ecological and geomorphological variables at landscape level were more influential. Additionally, human activities affected in greater proportion to colonies situated in Mediterranean forests. For the first time, a meta-analysis regarding the factors determining nest-site selection heterogeneity for a single species at broad scale was achieved. It is essential to homogenize and coordinate experimental design in modelling the selection of species' ecological requirements in order to avoid that differences in results among studies would be due to methodological heterogeneity. This would optimize best conservation and management practices for habitats and species in

  3. Effect of heterogeneous Fenton-like pre-treatment on anaerobic granular sludge performance and microbial community for the treatment of traditional Chinese medicine wastewater.

    Science.gov (United States)

    Su, Chengyuan; Li, Weiguang; Lu, Yuxiang; Chen, Menglin; Huang, Zhi

    2016-08-15

    The effect of a heterogeneous Fenton-like pre-treatment on the anaerobic processes, characteristics and microbial community of sludge was investigated for traditional Chinese medicine (TCM) wastewater containing rhein. When the concentrations of rhein were 50mg/L and 100mg/L, the toxic effect was physiological toxicity for anaerobic granular sludge. Using a single double circle (DC) reactor for the treatment of TCM wastewater containing rhein at concentrations of 15-20mg/L, the chemical oxygen demand (COD) removal rate was 69%, and coenzyme F420 was nearly undetectable in the 3D-excitation-emission matrix (EEM) spectra of soluble microbial products (SMP). The abundances of Methanoregula, Methanobacterium, Methanosphaerula were only 5.57%, 2.39% and 1.08% in the DC reactor, respectively. TCM wastewater containing rhein could be successfully treated by the combination of the heterogeneous Fenton-like pre-treatment and the DC reactor processes, and the COD removal rate reached 95%. Meanwhile, the abundances of Methanoregula, Methanobacterium, Methanosphaerula increased to 22.5%, 18.5%, and 13.87%, respectively. For the bacterial community, the abundance of Acidobacteria_Gp6 decreased from 6.99% to 1.07%, while the abundances of Acidobacteria_Gp1 and Acidobacteria_Gp2 increased from 1.61% to 6.55% and from 1.28% to 5.87%, respectively. PMID:27107235

  4. Heterogeneous deformation of metals (copper, tantalum, uranium, titanium) at convergence of cylindrical apertures having small diameters under effect of shock waves

    Science.gov (United States)

    Andrey, Malyshev; Dmitriy, Zamotaev; Olga, Ignatova; Michail, Tkachenko; Erich, Shepelev; Olga, Tyupanova; Aleksey, Podurets; Anna, Balandina; Irina, Kondrokhina

    2013-06-01

    Construction metals undergo loadings of various types during high-velocity deformation. As a result, there are different structural changes and, in particular, varying of mechanical properties. One of these complex structural changes is the process of formation of heterogeneous localized shear bands (LSB) of the twinning nature and the associated temporal decrease of dynamic strength in strong shock waves. The earlier investigations in this area point to the fact that the process of LSB formation has the threshold character, and pressure is the main criterion. So, it is shown in work that LSB formation occurs in coarse-grained copper after effect of shock wave with the amplitude 28-30 GPa. In this work, within the investigation of convergence of cylindrical channels having small diameters under effect of planar shock waves, it is shown that LSB can be formed in metals, and flow stops being homogeneous at rather low loading level (up to 10 GPa). In this case, the level of plastic strain and its rate are the main factors, which are responsible for heterogeneous deformation. The authors present results of experimental and metallographic researches for some metals, which are copper with various grain sizes, tantalum, uranium, and titanium alloys.

  5. Effects of nutrition spatial heterogeneity on root traits and carbon usage by roots of Cercis chinensis seedlings in split root rooms

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In natural ecosystems, nutrition available for plants shows great spatial heterogeneity. Much is known about plant root responses to the spatial heterogeneity of nutrition, but little is known about carbon usage in roots in nutrition-deficient patches and its effect on root longevity. In this study, split-room boxes were used for culture of Cercis chinensis seedlings, and the small rooms were supplied with different nutrition levels. The number of the first-order roots in the rooms with nutrition supply was significantly higher than that in the rooms with deficient nutrition. Specific root length (SRL) of the first-order roots in the rooms with deficient nutrition reached its peak at day 64 after nutrition treatment. There was no significant SRL differences between the two order roots during the experiment. Biomass of the first-order roots in the rooms without nutrition supply was significantly less than that of the first-order roots in the rooms with nutrition supply from day 64 to 96. The total biomass of the lateral roots in the rooms without nu-trition supply decreased from day 64 to 96. The activities of the enzymes in roots in the rooms without nutrition supply increased and the activities of alkaline invertases in roots in the two sides of split box did not change significantly. The activities of the enzymes in roots in the rooms without nutrition supply increased gradually. These results suggest that nutrition spatial heterogeneity induced the changes in root traits and plants actively controlled carbon usage in roots in nutrition-deficient patches by regulating the activities of invertases and sucrose synthases, resulting in the reduction in carbon usage in the roots in nutrition-deficient patches.

  6. The impact of horizontal heterogeneities, cloud fraction, and liquid water path on warm cloud effective radii from CERES-like Aqua MODIS retrievals

    Directory of Open Access Journals (Sweden)

    D. Painemal

    2013-10-01

    Full Text Available The impact of horizontal heterogeneities, liquid water path (LWP from AMSR-E, and cloud fraction (CF on MODIS cloud effective radius (re, retrieved from the 2.1 μm (re2.1 and 3.8 μm (re3.8 channels, is investigated for warm clouds over the southeast Pacific. Values of re retrieved using the CERES algorithms are averaged at the CERES footprint resolution (∼20 km, while heterogeneities (Hσ are calculated as the ratio between the standard deviation and mean 0.64 μm reflectance. The value of re2.1 strongly depends on CF, with magnitudes up to 5 μm larger than those for overcast scenes, whereas re3.8 remains insensitive to CF. For cloudy scenes, both re2.1 and re3.8 increase with Hσ for any given AMSR-E LWP, but re2.1 changes more than for re3.8. Additionally, re3.8–re2.1 differences are positive (Hσ 45 gm−2, and negative (up to −4 μm for larger Hσ. While re3.8–re2.1 differences in homogeneous scenes are qualitatively consistent with in situ microphysical observations over the region of study, negative differences – particularly evinced in mean regional maps – are more likely to reflect the dominant bias associated with cloud heterogeneities rather than information about the cloud vertical structure. The consequences for MODIS LWP are also discussed.

  7. Applied heterogeneous catalysis

    International Nuclear Information System (INIS)

    This reference book explains the scientific principles of heterogeneous catalysis while also providing details on the methods used to develop commercially viable catalyst products. A section of the book presents reactor design engineering theory and practices for the profitable application of these catalysts in large-scale industrial processes. A description of the mechanisms and commercial applications of catalysis is followed by a review of catalytic reaction kinetics. There are five chapters on selecting catalyst agents, developing and preparing industrial catalysts, measuring catalyst properties, and analyzing the physico-chemical characteristics of solid catalyst particles. The final chapter reviews the elements of catalytic reactor design, with emphasis on flow regimes vs. reactor types, heat and mass transfer in reactor beds, single- and multi-phase flows, and the effects of thermodynamics and other catalyst properties on the process flow scheme

  8. A Carapace-Like Bony ‘Body Tube’ in an Early Triassic Marine Reptile and the Onset of Marine Tetrapod Predation

    OpenAIRE

    Xiao-hong Chen; Ryosuke Motani; Long Cheng; Da-yong Jiang; Olivier Rieppel

    2014-01-01

    Parahupehsuchus longus is a new species of marine reptile from the Lower Triassic of Yuan'an County, Hubei Province, China. It is unique among vertebrates for having a body wall that is completely surrounded by a bony tube, about 50 cm long and 6.5 cm deep, comprising overlapping ribs and gastralia. This tube and bony ossicles on the back are best interpreted as anti-predatory features, suggesting that there was predation pressure upon marine tetrapods in the Early Triassic. There is at least...

  9. Heterogeneous Social Preferences

    OpenAIRE

    Erlei, Mathias

    2003-01-01

    Recent research has shown the usefulness of social preferences for explaining behavior in laboratory experiments. This paper demonstrates that models of social preferences are particularly powerful in explaining behavior if they are embedded in a setting of heteroge-neous actors with heterogeneous (social) preferences. For this purpose a simple model is in-troduced that combines the basic ideas of inequity aversion, social welfare preferences, recip-rocity and heterogeneity. This model is app...

  10. A carapace-like bony 'body tube' in an early triassic marine reptile and the onset of marine tetrapod predation.

    Directory of Open Access Journals (Sweden)

    Xiao-hong Chen

    Full Text Available Parahupehsuchus longus is a new species of marine reptile from the Lower Triassic of Yuan'an County, Hubei Province, China. It is unique among vertebrates for having a body wall that is completely surrounded by a bony tube, about 50 cm long and 6.5 cm deep, comprising overlapping ribs and gastralia. This tube and bony ossicles on the back are best interpreted as anti-predatory features, suggesting that there was predation pressure upon marine tetrapods in the Early Triassic. There is at least one sauropterygian that is sufficiently large to feed on Parahupehsuchus in the Nanzhang-Yuan'an fauna, together with six more species of potential prey marine reptiles with various degrees of body protection. Modern predators of marine tetrapods belong to the highest trophic levels in the marine ecosystem but such predators did not always exist through geologic time. The indication of marine-tetrapod feeding in the Nanzhang-Yuan'an fauna suggests that such a trophic level emerged for the first time in the Early Triassic. The recovery from the end-Permian extinction probably proceeded faster than traditionally thought for marine predators. Parahupehsuchus has superficially turtle-like features, namely expanded ribs without intercostal space, very short transverse processes, and a dorsal outgrowth from the neural spine. However, these features are structurally different from their turtle counterparts. Phylogeny suggests that they are convergent with the condition in turtles, which has a fundamentally different body plan that involves the folding of the body wall. Expanded ribs without intercostal space evolved at least twice and probably even more among reptiles.

  11. The effect of homogeneous and heterogeneous review pairs on student achievement and attitude when utilizing computer-assisted instruction in middle-level Earth science classes

    Science.gov (United States)

    Lyon, Ellen Beth

    1998-09-01

    This research project investigated the influence of homogeneous (like-ability) review pairs coupled with heterogeneous (mixed-ability) cooperative learning groups using computer-assisted instruction (CAI) on academic achievement and attitude toward science in eighth grade Earth science students. Subjects were placed into academic quartiles (Hi, Med-Hi, Med-Lo, and Lo) based on achievement. Cooperative learning groups of four (one student from each academic quartile) were formed in all classes, within which students completed CAI through a software package entitled Geoscience Education Through Interactive Technology, or GETITspTM. Each day, when computer activities were completed, students in the experimental classes were divided into homogeneous review pairs to review their work. The students in the control classes were divided into heterogeneous review pairs to review their work. The effects of the experimental treatment were measured by pretest, posttest, and delayed posttest measures, by pre- and post-student attitude scales, and by evaluation of amendments students made to their work during the time spent in review pairs. Results showed that student achievement was not significantly influenced by placement in homogeneous or heterogeneous review pairs, regardless of academic quartile assignment. Student attitude toward science as a school subject did not change significantly due to experimental treatment. Achievement retention of students in experimental and control groups within each quartile showed no significant difference. Notebook amendment patterns showed some significant differences in a few categories. For the Hi quartile, there were significant differences in numbers of deletion amendments and substitution amendments between the experimental and the control group. In both cases, subjects in the experimental group (homogeneous review pairs) made greater number of amendments then those in the control group (heterogeneous review pairs). For the Lo quartile

  12. Local cascades induced global contagion: How heterogeneous thresholds, exogenous effects, and unconcerned behaviour govern online adoption spreading

    Science.gov (United States)

    Karsai, Márton; Iñiguez, Gerardo; Kikas, Riivo; Kaski, Kimmo; Kertész, János

    2016-06-01

    Adoption of innovations, products or online services is commonly interpreted as a spreading process driven to large extent by social influence and conditioned by the needs and capacities of individuals. To model this process one usually introduces behavioural threshold mechanisms, which can give rise to the evolution of global cascades if the system satisfies a set of conditions. However, these models do not address temporal aspects of the emerging cascades, which in real systems may evolve through various pathways ranging from slow to rapid patterns. Here we fill this gap through the analysis and modelling of product adoption in the world’s largest voice over internet service, the social network of Skype. We provide empirical evidence about the heterogeneous distribution of fractional behavioural thresholds, which appears to be independent of the degree of adopting egos. We show that the structure of real-world adoption clusters is radically different from previous theoretical expectations, since vulnerable adoptions—induced by a single adopting neighbour—appear to be important only locally, while spontaneous adopters arriving at a constant rate and the involvement of unconcerned individuals govern the global emergence of social spreading.

  13. Sap flow for beech (Fagus sylvatica L.) in a natural and a managed forest-effect of spatial heterogeneity

    DEFF Research Database (Denmark)

    Dalsgaard, Lise; Mikkelsen, Teis Nørgaard; Bastrup-Birk, Annemarie

    2011-01-01

    using non-linear statistical methods with air vapour pressure deficit (D, hPa) and global radiation (R-g, J m(-2) day(-1)), along with constraints imposed by reductions in soil water content (SWC). SWC was measured as volumetric % using time domain reflectometry. The daily integrated J(s) (J(s-sum)) for...... trees growing in the evenly spaced MAN stand and trees in canopy and closed forest positions in NAT stand decreased as the availability of soil moisture was reduced. In the heterogeneous NAT stand, SWC in a recently formed canopy gap remained high throughout the vegetation period. Based on regression......(s-sum) in the outer 20 mm of the xylem in NAT was lower than that in MAN and the rate of decline in J(s) with xylem depth was less in NAT than in MAN. In MAN, J(s-sum) in deep and outer xylem was negatively affected at low soil moisture availability; in NAT, this was the case for only the outer xylem...

  14. Effect of spatial heterogeneities of water fluxes and application pattern on cadusafos fate on banana-cultivated andosols.

    Science.gov (United States)

    Saison, C; Cattan, P; Louchart, X; Voltz, M

    2008-12-24

    In tropical humid environments under intensive banana production, pesticide transfer in waters can be of particular concern due to heavy rainfall, steep slopes, and soils with high infiltration capacities. The transfer in percolation and runoff waters of the nematicide cadusafos was investigated during a three month field experiment. The spatial heterogeneity of the banana plantation was taken into account by measuring percolation fluxes both under the banana plants and in the interrows with a specially designed lysimeter device installed at 60 cm depth. At the field scale, 0.34% of the pesticide applied was transferred in percolation, 0.13% in runoff. Forty-nine percent of cadusafos losses occurred by percolation under the banana plants, 23% by interrow percolation, and 28% by runoff. Losses were highest during the three weeks following cadusafos application, and this is also when dissipation in the soil was highest (calculated half-life in the soil: 7d). After this period, losses of cadusafos were low, both in soil and waters. Under the banana plant, saturated fluxes carried most of the pesticide, despite total percolation fluxes being at least five-times higher than saturated ones. Although overall pesticide transfer in water was low (0.5% of applied), it was not negligible due to the frequency of pesticide application in these areas. PMID:19053376

  15. Effects of transverse electric field and heterogeneity of a poorly electrically conducting fluid saturated nanoporous zeolites acquiring smart material properties

    International Nuclear Information System (INIS)

    In this paper we explain a Mathematical Model involving Darcy linear drag, Forchheimer quadratic drag, horizontal density gradient and the variation of electrical conductivity due to organic substances dissolved in a heterogeneous Boussinesq poorly conducting couple stress fluid flow (PCPCSFF) through Nano Porous Zeolites regarded as densely packed porous media. Initially, the flow is at rest and set in motion due to initial piecewise horizontal concentration gradient. Analytical solutions, for electric potential using the Maxwell field equations and for velocity and density using nonlinear Darcy – Forchheimer equation in the presence of couple stress and electric force are obtained using the method of time series evolution. The analytical solutions for streamlines and density are computed for different values of time, t, for a particular value of electric number W1 and couple stress parameterβ and the results are depicted graphically in figures 1 and 2. From these figures we found that the streamlines are closer in the region of x0 and the density profiles are concentrated in the lower region and develop curvature in the presence of electric field and couple stress parameter. The physical reason for the nature of streamlines and density profiles are given in the last section and some important conclusions are drawn. (author)

  16. Effect of heterogeneous precipitation caused by segregation of substitutional and interstitial elements on mechanical properties of a β-type Ti alloy

    Energy Technology Data Exchange (ETDEWEB)

    Narita, Kengo, E-mail: narita@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Medical Department, Maruemu Works Co., LTD., 4-7-12 Nozaki, Daito-shi 574-0015 (Japan); Niinomi, Mitsuo; Nakai, Masaaki [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Suyalatu [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Department of Materials Science and Engineering, Graduate School of Engineering, Osaka University, 2-1, Yamada-Oka, Suita, Osaka 565-0871 (Japan)

    2015-09-03

    This study investigates the effect of heterogeneous precipitation induced by the segregation of substitutional and interstitial elements in Ti–29Nb–13Ta–4.6Zr alloy (TNTZ) on its mechanical properties. For this, samples both with and without segregation of substitutional elements were prepared, with only the latter being subjected to long-term homogenization. It was found that micro-scale segregation of substitutional elements such as Nb, Ta, and Zr does not significantly affect mechanical properties such as fatigue strength, not even if heterogeneous precipitation occurs as a result of this segregation. On the other hand, segregation of interstitial elements was achieved by controlling the aging time. The segregation of interstitial elements creates precipitate-free zones (PFZs), grain boundary (GB) plates, and Widmanstätten α phases with migrating O atoms that all significantly affect the mechanical properties. Specifically, the PFZs have the potential to improve fatigue life, while the Widmanstätten α phase increases the tensile strength and reduces the fatigue ratio, the GB-plates reduce elongation, These results indicate that the formation of a Widmanstätten α phase by the migration of interstitial elements has a varying influence on the tensile and fatigue properties.

  17. Effect of heterogeneous precipitation caused by segregation of substitutional and interstitial elements on mechanical properties of a β-type Ti alloy

    International Nuclear Information System (INIS)

    This study investigates the effect of heterogeneous precipitation induced by the segregation of substitutional and interstitial elements in Ti–29Nb–13Ta–4.6Zr alloy (TNTZ) on its mechanical properties. For this, samples both with and without segregation of substitutional elements were prepared, with only the latter being subjected to long-term homogenization. It was found that micro-scale segregation of substitutional elements such as Nb, Ta, and Zr does not significantly affect mechanical properties such as fatigue strength, not even if heterogeneous precipitation occurs as a result of this segregation. On the other hand, segregation of interstitial elements was achieved by controlling the aging time. The segregation of interstitial elements creates precipitate-free zones (PFZs), grain boundary (GB) plates, and Widmanstätten α phases with migrating O atoms that all significantly affect the mechanical properties. Specifically, the PFZs have the potential to improve fatigue life, while the Widmanstätten α phase increases the tensile strength and reduces the fatigue ratio, the GB-plates reduce elongation, These results indicate that the formation of a Widmanstätten α phase by the migration of interstitial elements has a varying influence on the tensile and fatigue properties

  18. PET imaging for the quantification of biologically heterogeneous tumours: measuring the effect of relative position on image-based quantification of dose-painting targets

    Science.gov (United States)

    McCall, Keisha C; Barbee, David L; Kissick, Michael W; Jeraj, Robert

    2010-01-01

    Quantitative imaging of tumours represents the foundation of customized therapies and adaptive patient care. As such, we have investigated the effect of patient positioning errors on the reproducibility of images of biologically heterogeneous tumours generated by a clinical PET/CT system. A commercial multi-slice PET/CT system was used to acquire 2D and 3D PET images of a phantom containing multiple spheres of known volumes and known radioactivity concentrations and suspended in an aqueous medium. The spheres served as surrogates for sub-tumour regions of biological heterogeneities with dimensions of 5–15 mm. Between image acquisitions, a motorized-arm was used to reposition the spheres in 1 mm intervals along either the radial or the axial direction. Images of the phantom were reconstructed using typical diagnostic reconstruction techniques, and these images were analysed to characterize and model the position-dependent changes in contrast recovery. A simulation study was also conducted to investigate the effect of patient position on the reproducibility of PET imaging of biologically heterogeneous head and neck (HN) tumours. For this simulation study, we calculated the changes in image intensity values that would occur with changes in the relative position of the patients at the time of imaging. PET images of two HN patients were used to simulate an imaging study that incorporated set-up errors that are typical for HN patients. One thousand randomized positioning errors were investigated for each patient. As a result of the phantom study, a position-dependent trend was identified for measurements of contrast recovery of small objects. The peak contrast recovery occurred at radial and axial positions that coincide with the centre of the image voxel. Conversely, the minimum contrast recovery occurred when the object was positioned at the edges of the image voxel. Changing the position of high contrast spheres by one-half the voxel dimension lead to errors in the

  19. PET imaging for the quantification of biologically heterogeneous tumours: measuring the effect of relative position on image-based quantification of dose-painting targets

    Energy Technology Data Exchange (ETDEWEB)

    McCall, Keisha C; Barbee, David L; Kissick, Michael W; Jeraj, Robert [Department of Medical Physics, University of Wisconsin, 1111 Highland Ave, Madison, WI 53705 (United States)

    2010-05-21

    Quantitative imaging of tumours represents the foundation of customized therapies and adaptive patient care. As such, we have investigated the effect of patient positioning errors on the reproducibility of images of biologically heterogeneous tumours generated by a clinical PET/CT system. A commercial multi-slice PET/CT system was used to acquire 2D and 3D PET images of a phantom containing multiple spheres of known volumes and known radioactivity concentrations and suspended in an aqueous medium. The spheres served as surrogates for sub-tumour regions of biological heterogeneities with dimensions of 5-15 mm. Between image acquisitions, a motorized-arm was used to reposition the spheres in 1 mm intervals along either the radial or the axial direction. Images of the phantom were reconstructed using typical diagnostic reconstruction techniques, and these images were analysed to characterize and model the position-dependent changes in contrast recovery. A simulation study was also conducted to investigate the effect of patient position on the reproducibility of PET imaging of biologically heterogeneous head and neck (HN) tumours. For this simulation study, we calculated the changes in image intensity values that would occur with changes in the relative position of the patients at the time of imaging. PET images of two HN patients were used to simulate an imaging study that incorporated set-up errors that are typical for HN patients. One thousand randomized positioning errors were investigated for each patient. As a result of the phantom study, a position-dependent trend was identified for measurements of contrast recovery of small objects. The peak contrast recovery occurred at radial and axial positions that coincide with the centre of the image voxel. Conversely, the minimum contrast recovery occurred when the object was positioned at the edges of the image voxel. Changing the position of high contrast spheres by one-half the voxel dimension lead to errors in the

  20. Experimental constraints on the energy budget of dynamic gouge formation: effects of rock strength, material heterogeneity, and initial flaw characteristics

    Science.gov (United States)

    Griffith, Ashley; Barber, Troy; Borjas, Christopher; Ghaffari, Hamed

    2016-04-01

    Fault core materials are characterized by substantial grain size reduction relative to host and damage zone rocks. The properties of these materials control fault strength and frictional behavior, and they record valuable information about rupture and slip processes. At high strain rates and large stress amplitudes characteristic of earthquake rupture tips, rock failure passes through a fragmentation transition from discrete fracture to pulverization; therefore much of the observed grain size reduction at the leading edge of propagating earthquake ruptures. Past examinations of particle size distributions in gouge formed in the cores of natural faults have led to contrasting conclusions that during a single event, the energy associated with creation of new surface area during this grain size reduction can be as large as 50%, or as little as particle size measurement and (B) uncertainty regarding the variety of (not-necessarily coseismic) physico-chemical processes that may contribute to the observed grain size reduction. Here we study the micromechanics and energy budget of dynamic rock fragmentation under impulsive compressive loads using a Split Hopkinson Pressure Bar. We present new experimental results on Arkansas Novaculite and Westerly Granite coupled with microstructural observations and BET surface area measurements of post-mortem specimens. We show that the energy partitioned into creation of new surface areas approaches a significant portion of the total dissipated energy during our experiments, but this partitioning can be buffered by the presence of flaws and/or significant material heterogeneity. The results of this work have important implications for lithologic controls on gouge formation and energy partitioning during earthquakes.

  1. Effects of nutrient heterogeneity and competition on root architecture of spruce seedlings: implications for an essential feature of root foraging.

    Directory of Open Access Journals (Sweden)

    Hongwei Nan

    Full Text Available BACKGROUND: We have limited understanding of root foraging responses when plants were simultaneously exposed to nutrient heterogeneity and competition, and our goal was to determine whether and how plants integrate information about nutrients and neighbors in root foraging processes. METHODOLOGY/PRINCIPAL FINDINGS: The experiment was conducted in split-containers, wherein half of the roots of spruce (Picea asperata seedlings were subjected to intraspecific root competition (the vegetated half, while the other half experienced no competition (the non-vegetated half. Experimental treatments included fertilization in the vegetated half (FV, the non-vegetated half (FNV, and both compartments (F, as well as no fertilization (NF. The root architecture indicators consisted of the number of root tips over the root surface (RTRS, the length percentage of diameter-based fine root subclasses to total fine root (SRLP, and the length percentage of each root order to total fine root (ROLP. The target plants used novel root foraging behaviors under different combinations of neighboring plant and localized fertilization. In addition, the significant increase in the RTRS of 0-0.2 mm fine roots after fertilization of the vegetated half alone and its significant decrease in fertilizer was applied throughout the plant clearly showed that plant root foraging behavior was regulated by local responses coupled with systemic control mechanisms. CONCLUSIONS/SIGNIFICANCE: We measured the root foraging ability for woody plants by means of root architecture indicators constructed by the roots possessing essential nutrient uptake ability (i.e., the first three root orders, and provided new evidence that plants integrate multiple forms of environmental information, such as nutrient status and neighboring competitors, in a non-additive manner during the root foraging process. The interplay between the responses of individual root modules (repetitive root units to localized

  2. Heterogeneous network architectures

    DEFF Research Database (Denmark)

    Christiansen, Henrik Lehrmann

    2006-01-01

    Future networks will be heterogeneous! Due to the sheer size of networks (e.g., the Internet) upgrades cannot be instantaneous and thus heterogeneity appears. This means that instead of trying to find the olution, networks hould be designed as being heterogeneous. One of the key equirements here...... is flexibility. This thesis investigates such heterogeneous network architectures and how to make them flexible. A survey of algorithms for network design is presented, and it is described how using heuristics can increase the speed. A hierarchical, MPLS based network architecture is described...... and it is discussed that it is advantageous to heterogeneous networks and illustrated by a number of examples. Modeling and simulation is a well-known way of doing performance evaluation. An approach to event-driven simulation of communication networks is presented and mixed complexity modeling, which can simplify...

  3. The Effect of Single Crystal Elastic and Plastic Anisotropy on Strain Heterogeneity: Comparison of Olivine to Other Common Minerals

    Science.gov (United States)

    Cline, C. J., II; Burnley, P. C.

    2013-12-01

    stress field heterogeneity within a deforming polycrystal of the same material. As a starting point for comparisons, we have studied a deformed polycrystal produced from a powdered single crystal of San Carlos olivine. The samples were annealed in-situ and deformed using the D-DIA apparatus (located at the NSLS beamline X17B2) at pressures between 3.5 and 5GPa, and temperatures ranging from 700 to 900°C at a strain rate of 1.45x10-5s-1. High resolution electron backscatter diffraction (EBSD) was used to analyze of the orientation of kink bands within the experiments. The results show that the orientation of the local stress tensors can vary from that of the macroscopic stress tensor by up to 35°. EBSD results from other deformed crystalline materials will also be presented in further detail.

  4. Spectral variability on primitive asteroids of the Themis and Beagle families: Space weathering effects or parent body heterogeneity?

    Science.gov (United States)

    Fornasier, S.; Lantz, C.; Perna, D.; Campins, H.; Barucci, M. A.; Nesvorny, D.

    2016-05-01

    having albedos and spectral slopes similar to the young Beagle members. Alternative scenarios are proposed including heterogeneity in the parent body having a compositional gradient with depth, and/or the survival of projectile fragments having a different composition than the parent body.

  5. Modeling the effects of geological heterogeneity and metamorphic dehydration on slow slip and shallow deformation in subduction zones

    Science.gov (United States)

    Skarbek, Robert M.

    Slow slip and tectonic tremor in subduction zones take place at depths (˜20 - 50 km) where there is abundant evidence for distributed shear over broad zones (˜10 - 103 m) composed of rocks with marked differences in mechanical properties and for near lithostatic pore pressures along the plate interface where the main source of fluids must be attributed to chemical dehydration reactions. In Chapter II, I model quasi-dynamic rupture along faults composed of material mixtures characterized by different rate-and-state-dependent frictional properties to determine the parameter regime capable of producing slow slip in an idealized subduction zone setting. Keeping other parameters fixed, the relative proportions of velocity-weakening (VW) and velocity-strengthening (VS) materials control the sliding character (stable, slow, or dynamic) along the fault. The stability boundary between slow and dynamic is accurately described by linear analysis of a double spring-slider system with VW and VS blocks. In Chapter III, I model viscoelastic compaction of material subducting through the slow slip and tremor zone in the presence of pressure and temperature-dependent dehydration reactions. A dehydration fluid source is included using 1) a generalized basalt dehydration reaction in subducting oceanic crust or 2) a general nonlinear kinetic reaction rate law parameterized for an antigorite dehydration reaction. Pore pressures in excess of lithostatic values are a robust feature of simulations that employ parameters consistent with the geometry of the Cascadia subduction margin. Simulations that include viscous deformation uniformly generate traveling porosity waves that transport increased fluid pressures within the slow slip region. Slow slip and tremor also occur in shallow (prism sections of subduction zones. In Chapter IV, I examine how geologic heterogeneities affect the mechanics of accretionary prisms in subduction zones by showing how spatial variations in pore pressure

  6. Up-scaling of a two-phase flow model including gravity effect in geological heterogeneous media: application to CO2 sequestration

    International Nuclear Information System (INIS)

    This work deals with the mathematical modeling and the numerical simulation of the migration under gravity and capillarity effects of the supercritical CO2 injected into a geological heterogeneous sequestration site. The simulations are performed with the code DuMux. Particularly, we consider the up-scaling, from the cell scale to the reservoir scale, of a two-phase (CO2 -brine) flow model within a periodic stratified medium made up of horizontal low permeability barriers, continuous or discontinuous. The up-scaling is done by the two-scale asymptotic method. First, we consider perfectly layered media. An homogenized model is developed and validated by numerical simulation for different values of capillary number and the incident flux of CO2. The homogenization method is then applied to the case of a two-dimensional medium made up of discontinuous layers. Due to the gravity effect, the CO2 accumulates under the low permeability layers, which leads to a non-standard local mathematical problem. This stratification is modeled using the gravity current approach. This approach is then extended to the case of semi-permeable strata taking into account the capillarity. The up-scaled model is compared with numerical simulations for different types of layers, with or without capillary pressure, and its limit of validity is discussed in each of these cases. The final part of this thesis is devoted to the study of the parallel computing performances of the code DuMux to simulate the injection and migration of CO2 in three-dimensional heterogeneous media (layered periodic media, fluvial media and reservoir model SPE 10). (author)

  7. How effective are energy efficiency and renewable energy in curbing CO2 emissions in the long run? A heterogeneous panel data analysis

    International Nuclear Information System (INIS)

    Energy efficiency and renewable energy are considered to be two indispensable solutions to control GHG (greenhouse gas) emissions. Moreover, industrialization is at the center of discussions on the roles of countries to reduce CO2 emissions. However, the literature is underprovided to understand the long run contribution of energy efficiency, renewable energy and industrial composition in reducing GHG emissions at the macro level. In this study, we differentiate the effects of economic activity, energy efficiency, economic structure and use of renewable energy resources on CO2 emissions. We develop energy efficiency indices for thirty six countries for the period of 1971–2009 and use a CCE (common correlated effects) estimator model that is consistent under heterogeneity and cross-sectional dependence. We find a positive significant effect of energy efficiency on CO2 emissions in the long-run. Similarly, substituting renewable energy for non-renewable energy reduces CO2 emissions in the long-run. Our results ensure widely discussed roles of energy efficiency and renewable energy in curbing CO2 emissions. Furthermore, the scale of economic activity measured by real income and industrialization have significant positive effect on CO2 emissions. - Highlights: • We model long-run effects of energy efficiency and renewable energy on CO2. • Energy efficiency significantly reduces CO2 emissions over the long term. • Replacing non-renewable energy sources with renewable ones reduces CO2 emissions. • CO2 emissions rise with increases in real income. • Industrial composition affects CO2 emissions

  8. Heterogeneous cellular networks

    CERN Document Server

    Hu, Rose Qingyang

    2013-01-01

    A timely publication providing coverage of radio resource management, mobility management and standardization in heterogeneous cellular networks The topic of heterogeneous cellular networks has gained momentum in industry and the research community, attracting the attention of standardization bodies such as 3GPP LTE and IEEE 802.16j, whose objectives are looking into increasing the capacity and coverage of the cellular networks. This book focuses on recent progresses,  covering the related topics including scenarios of heterogeneous network deployment, interference management i

  9. Sci—Fri PM: Topics — 04: What if bystander effects influence cell kill within a target volume? Potential consequences of dose heterogeneity on TCP and EUD on intermediate risk prostate patients

    International Nuclear Information System (INIS)

    In vitro evidence has suggested that radiation induced bystander effects may enhance non-local cell killing which may influence radiotherapy treatment planning paradigms. This work applies a bystander effect model, which has been derived from published in vitro data, to calculate equivalent uniform dose (EUD) and tumour control probability (TCP) and compare them with predictions from standard linear quadratic (LQ) models that assume a response due only to local absorbed dose. Comparisons between the models were made under increasing dose heterogeneity scenarios. Dose throughout the CTV was modeled with normal distributions, where the degree of heterogeneity was then dictated by changing the standard deviation (SD). The broad assumptions applied in the bystander effect model are intended to place an upper limit on the extent of the results in a clinical context. The bystander model suggests a moderate degree of dose heterogeneity yields as good or better outcome compared to a uniform dose in terms of EUD and TCP. Intermediate risk prostate prescriptions of 78 Gy over 39 fractions had maximum EUD and TCP values at SD of around 5Gy. The plots only dropped below the uniform dose values for SD ∼ 10 Gy, almost 13% of the prescribed dose. The bystander model demonstrates the potential to deviate from the common local LQ model predictions as dose heterogeneity through a prostate CTV is varies. The results suggest the potential for allowing some degree of dose heterogeneity within a CTV, although further investigations of the assumptions of the bystander model are warranted

  10. Diffusion in heterogeneous media

    Science.gov (United States)

    Zhang, Y.; Liu, L.

    2012-12-01

    Diffusion in heterogeneous media has been investigated for over forty years. However, the fundamental equations for bulk (effective) diffusivity in multi-phase systems were incorrect because of the use of an inappropriate similarity between diffusion and other physical properties such as thermal conductivity. The mistake has permeated through the literature and textbooks. Specifically, the role of concentration partitioning between different phases in diffusion was not considered in such similarity relations. In this work, we present the correct method to derive such relations in heterogeneous media. Barrer [1] used the similarity between diffusivity and thermal conductivity to derive the relation between the bulk (effective) diffusivity and the individual-phase diffusivities. The approach was followed by many others [2-4]. Unfortunately the similarity approach by Barrer [1] is incorrect because there is also dissimilarity. The key difference is that, even though heat conduction and mass diffusion are characterized by a similar flux equation, in heat conduction, T is continuous across phase boundaries, whereas in diffusion, C is usually not continuous across phase boundaries. The concentration in each phase plays a major role in controlling the contribution by the phase to the bulk diffusive flux and hence the bulk diffusivity. For example, if the concentration of a component in a phase is very low, even if the diffusivity in the phase is high, the contribution of diffusion in that phase to the bulk diffusion flux can still be negligible. Hence, previous models for diffusivity in composite materials or multi-mineral rocks, no matter how sophisticated, are fundamentally wrong because the foundation is a mistake. Correcting the mistake is straightforward. The mass flux can be written in terms of chemical potential and mobility [5,6]. Because chemical potential is continuous across phase boundaries, the relation between bulk mobility and individual-phase mobilities is

  11. Transphyseal osseous bridges in experimental osteonecrosis of the femoral head of the rat. Histologic study of the bony bridges connecting the epiphyseal with the metaphyseal bony trabeculae through gaps in the physeal cartilage.

    Science.gov (United States)

    Peskin, B; Shupak, A; Misselevich, I; Zinman, C; Levin, D; Jacob, Z; Reis, D N; Boss, J H

    2001-07-01

    In view of the lifelong persistence of the physis, the femoral head of rats may serve to model Perthes disease and slipped capital femoral epiphysis. To produce osteonecrosis, the blood supply of one femoral head of 133, 6-month-old animals was severed by circumferentially incising the periosteum of the neck and cutting the ligamentum teres. The rats were killed 7 days to 90 days postoperatively. Associated with resorption of the necrotic bone and marrow, remodeling of the epiphysis was characterized by an ingrowth of vascularized fibrous tissue, formation of new bone and some cartilage, architectural deformation and flattening of the head. In 22 of 83 rats killed 30 days or more postoperatively, gaps in the continuity of the physeal cartilage were occupied by osseous bridges, connecting newly formed epiphyseal bony trabeculae with either the preexisting or newly formed metaphyseal osseous trabeculae. This healing mode may follow ischemic death of physeal chondrocytes or be owing to another mechanism, e.g., release of mediatory substances of inflammation. These findings raise the possibility that fixation of the healing epiphysis of a child's previously necrotic femoral head to the metaphysis occurs by transphyseal osseous growth in cases in which the physis is involved in the necrotic process. PMID:11497365

  12. Seeking for Labor Demand Heterogeneity

    OpenAIRE

    Dormont, Brigitte

    1996-01-01

    The aim of this paper is to examine whether the estimation of labor demand can be affected by individual behavior heterogeneity. We shall consider an error-components model with variable-coefficients, where the coefficients are random and vary accross firms according to the values of time-constant explanatory variables and to a random firm-specific effect. The specification of labor demand which stems from the variable coefficients hypothesis is estimated by the generalized method of moments ...

  13. Consolidation of Heterogeneous Terminology Resources

    OpenAIRE

    Vasiļjevs, Andrejs

    2010-01-01

    Andrejs Vasiļjevs This thesis researches data management and accessibility problems in the terminology domain. The thesis theoretically and practically demonstrates that the usability problems posed by the fragmentation and heterogeneity of terminology resources can be effectively solved with a federated multilingual database system that consolidates data representation and integration in authoring software. A unified consolidation methodology is proposed covering all major aspects from sc...

  14. Impairment of Bony Crypt Development Associated With Hexavalent Chromium Exposure During Tooth Eruption.

    Science.gov (United States)

    Sánchez, Luciana M; Lewicki, Marianela; De Lucca, Romina C; Ubios, Ángela M

    2015-12-01

    Improperly treated hexavalent chromium-containing industrial wastes contaminate drinking water, potentially affecting children taking breast milk or baby bottles prepared with infant formula. Thus, the aim of the present work was to determine the effect of this toxic on bone activity in the developing alveolus during tooth eruption of suckling Wistar rats intoxicated with potassium dichromate. Experimental animals received a daily dose of 12.5mg/kg body weight of potassium dichromate by gavage for 10 days; controls received an equivalent volume of saline solution. Histologic and histomorphometric studies of the mandible were performed. The data were statistically analyzed using Student's t test; statistical significance was set at a value of p hexavalent chromium is the result of a lower rate of bone remodeling in the developing alveolus. The obtained results show the importance of controlling toxic substances in drinking water, since their effects may alter the growth and development of subjects who were exposed during early infancy. PMID:27095619

  15. The effects of biotic and abiotic factors on the spatial heterogeneity of alpine grassland vegetation at a small scale on the Qinghai-Tibet Plateau (QTP), China.

    Science.gov (United States)

    Wen, Lu; Dong, Shi Kui; Li, Yuan Yuan; Sherman, Ruth; Shi, Jian Jun; Liu, De Mei; Wang, Yan Long; Ma, Yu Shou; Zhu, Lei

    2013-10-01

    Understanding the complex effects of biotic and abiotic factors on the composition of vegetation is very important for developing and implementing strategies for promoting sustainable grassland development. The vegetation-disturbance-environment relationship was examined in degraded alpine grasslands in the headwater areas of three rivers on the Qinghai-Tibet Plateau in this study. The investigated hypotheses were that (1) the heterogeneity of the vegetation of the alpine grassland is due to a combination of biotic and abiotic factors and that (2) at a small scale, biotic factors are more important for the distribution of alpine vegetation. On this basis, four transects were set along altitudinal gradients from 3,770 to 3,890 m on a sunny slope, and four parallel transects were set along altitudinal gradients on a shady slope in alpine grasslands in Guoluo Prefecture of Qinghai Province, China. It was found that biological disturbances were the major forces driving the spatial heterogeneity of the alpine grassland vegetation and abiotic factors were of secondary importance. Heavy grazing and intensive rat activity resulted in increases in unpalatable and poisonous weeds and decreased fine forages in the form of sedges, forbs, and grasses in the vegetation composition. Habitat degradation associated with biological disturbances significantly affected the spatial variation of the alpine grassland vegetation, i.e., more pioneer plants of poisonous or unpalatable weed species, such as Ligularia virgaurea and Euphorbia fischeriana, were found in bare patches. Environmental/abiotic factors were less important than biological disturbances in affecting the spatial distribution of the alpine grassland vegetation at a small scale. It was concluded that rat control and light grazing should be applied first in implementing restoration strategies. The primary vegetation in lightly grazed and less rat-damaged sites should be regarded as a reference for devising vegetation

  16. Teaching Heterogeneous Classes.

    Science.gov (United States)

    Millrood, Radislav

    2002-01-01

    Discusses an approach to teaching heterogeneous English-as-a-Second/Foreign-Language classes. Draws on classroom research data to describe the features of a success-building lesson context. (Author/VWL)

  17. Heterogeneous Calculation of ε

    International Nuclear Information System (INIS)

    A heterogeneous method of calculating the fast fission factor given by Naudet has been applied to the Carlvik - Pershagen definition of ε. An exact calculation of the collision probabilities is included in the programme developed for the Ferranti - Mercury computer

  18. Heterogeneous atmospheric chemistry

    Science.gov (United States)

    Schryer, D. R.

    1982-01-01

    The present conference on heterogeneous atmospheric chemistry considers such topics concerning clusters, particles and microparticles as common problems in nucleation and growth, chemical kinetics, and catalysis, chemical reactions with aerosols, electron beam studies of natural and anthropogenic microparticles, and structural studies employing molecular beam techniques, as well as such gas-solid interaction topics as photoassisted reactions, catalyzed photolysis, and heterogeneous catalysis. Also discussed are sulfur dioxide absorption, oxidation, and oxidation inhibition in falling drops, sulfur dioxide/water equilibria, the evidence for heterogeneous catalysis in the atmosphere, the importance of heterogeneous processes to tropospheric chemistry, soot-catalyzed atmospheric reactions, and the concentrations and mechanisms of formation of sulfate in the atmospheric boundary layer.

  19. A survey of informatics platforms that enable distributed comparative effectiveness research using multi-institutional heterogeneous clinical data

    OpenAIRE

    Sittig, Dean F; Hazlehurst, Brian L; Brown, Jeffrey; Murphy, Shawn; Rosenman, Marc; Tarczy-Hornoch, Peter; Wilcox, Adam B

    2012-01-01

    Comparative Effectiveness Research (CER) has the potential to transform the current healthcare delivery system by identifying the most effective medical and surgical treatments, diagnostic tests, disease prevention methods and ways to deliver care for specific clinical conditions. To be successful, such research requires the identification, capture, aggregation, integration, and analysis of disparate data sources held by different institutions with diverse representations of the relevant clin...

  20. Wages, Unemployment and Inequality with Heterogeneous Firms and Workers

    OpenAIRE

    Elhanan Helpman; Oleg Itskhoki; Stephen Redding

    2008-01-01

    In this paper we develop a multi-sector general equilibrium model of firm heterogeneity, worker heterogeneity and labor market frictions. We characterize the distributions of employment, unemployment, wages and income within and between sectors as a function of structural parameters. We find that greater firm heterogeneity increases unemployment, wage inequality and income inequality, whereas greater worker heterogeneity has ambiguous effects. We also find that labor market frictions have non...