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Sample records for re-operation rate varied

  1. Complications and re-operation rate after tension-band wiring of olecranon fractures

    DEFF Research Database (Denmark)

    Romero, J M; Miran, A; Jensen, Claus Hjorth

    2000-01-01

    Tension-band wire fixation of olecranon fractures leads to a high re-operation rate because of the need to remove the metalware. This problem has commonly been thought to be related mainly to the backing-out of the Kirschner wires. A retrospective study was carried out in 55 patients with displaced...... olecranon fractures operated on with the tension-band wiring technique, in whom there was an overall 71.7% re-operation rate. Complications were few and minor in most patients. The main reason for the removal of the metalware was a direct complaint from the patient (in 61.3% of all removals). A literature...

  2. Influence of surgeon's experience and supervision on re-operation rate after hip fracture surgery

    DEFF Research Database (Denmark)

    Palm, Henrik; Jacobsen, Steffen; Krasheninnikoff, Michael

    2006-01-01

    Society of Anaesthesiologists score, New Mobility Score, time to surgery and type of implant, surgery by unsupervised junior registrars was still a significant independent risk factor for re-operation in technically demanding proximal femoral fractures. CONCLUSION: Unsupervised junior registrars should......OBJECTIVE: To investigate the influence of the performing surgeon's experience and degree of supervision on re-operation rate among patients admitted with a proximal femoral fracture (PFF). METHODS: Prospective study of 600 consecutive patients with proximal femoral fracture in our multimodal...... rehabilitation programme, between 2002 and 2004. Re-operation rate was assessed 6 months postoperatively. Surgeons were grouped as unsupervised junior registrars versus experienced surgeons operating or supervising. Fractures were stratified as technically undemanding or demanding. RESULTS: Unsupervised junior...

  3. Influence of surgeon's experience and supervision on re-operation rate after hip fracture surgery

    DEFF Research Database (Denmark)

    Palm, Henrik; Jacobsen, Steffen; Krasheninnikoff, Michael

    2006-01-01

    Society of Anaesthesiologists score, New Mobility Score, time to surgery and type of implant, surgery by unsupervised junior registrars was still a significant independent risk factor for re-operation in technically demanding proximal femoral fractures. CONCLUSION: Unsupervised junior registrars should......OBJECTIVE: To investigate the influence of the performing surgeon's experience and degree of supervision on re-operation rate among patients admitted with a proximal femoral fracture (PFF). METHODS: Prospective study of 600 consecutive patients with proximal femoral fracture in our multimodal...... rehabilitation programme, between 2002 and 2004. Re-operation rate was assessed 6 months postoperatively. Surgeons were grouped as unsupervised junior registrars versus experienced surgeons operating or supervising. Fractures were stratified as technically undemanding or demanding. RESULTS: Unsupervised junior...

  4. Radiographic failure and rates of re-operation after acromioclavicular joint reconstruction: a comparison of surgical techniques.

    Science.gov (United States)

    Spencer, H T; Hsu, L; Sodl, J; Arianjam, A; Yian, E H

    2016-04-01

    To compare radiographic failure and re-operation rates of anatomical coracoclavicular (CC) ligament reconstructional techniques with non-anatomical techniques after chronic high grade acromioclavicular (AC) joint injuries. We reviewed chronic AC joint reconstructions within a region-wide healthcare system to identify surgical technique, complications, radiographic failure and re-operations. Procedures fell into four categories: (1) modified Weaver-Dunn, (2) allograft fixed through coracoid and clavicular tunnels, (3) allograft loop coracoclavicular fixation, and (4) combined allograft loop and synthetic cortical button fixation. Among 167 patients (mean age 38.1 years, (standard deviation (sd) 14.7) treated at least a four week interval after injury, 154 had post-operative radiographs available for analysis. Radiographic failure occurred in 33/154 cases (21.4%), with the lowest rate in Technique 4 (2/42 4.8%, p = 0.001). Half the failures occurred by six weeks, and the Kaplan-Meier survivorship at 24 months was 94.4% (95% confidence interval (CI) 79.6 to 98.6) for Technique 4 and 69.9% (95% CI 59.4 to 78.3) for the other techniques when combined. In multivariable survival analysis, Technique 4 had better survival than other techniques (Hazard Ratio 0.162, 95% CI 0.039 to 0.068, p = 0.013). Among 155 patients with a minimum of six months post-operative insurance coverage, re-operation occurred in 9.7% (15 patients). However, in multivariable logistic regression, Technique 4 did not reach a statistically significant lower risk for re-operation (odds ratio 0.254, 95% CI 0.05 to 1.3, p = 0.11). In this retrospective series, anatomical CC ligament reconstruction using combined synthetic cortical button and allograft loop fixation had the lowest rate of radiographic failure. Anatomical coracoclavicular ligament reconstruction using combined synthetic cortical button and allograft loop fixation had the lowest rate of radiographic failure. ©2016 The British Editorial

  5. High Re-Operation Rates Using Conserve Metal-On-Metal Total Hip Articulations

    DEFF Research Database (Denmark)

    Mogensen, S L; Jakobsen, Thomas; Christoffersen, Hardy;

    2016-01-01

    INTRODUCTION: Metal-on-metal hip articulations have been intensely debated after reports of adverse reactions and high failure rates. The aim of this study was to retrospectively evaluate the implant of a metal-on.metal total hip articulation (MOM THA) from a single manufacture in a two...

  6. An ETAS model with varying productivity rates

    Science.gov (United States)

    Harte, D. S.

    2014-07-01

    We present an epidemic type aftershock sequenc (ETAS) model where the offspring rates vary both spatially and temporally. This is achieved by distinguishing between those space-time volumes where the interpoint space and time distances are small, and those where they are considerably larger. We also question the nature of the background component in the ETAS model. Is it simply a temporal boundary correction (t = 0) or does it represent an additional tectonic process not described by the aftershock component? The form of these stochastic models should not be considered to be fixed. As we accumulate larger and better earthquake catalogues, GPS data, strain rates, etc., we have the ability to ask more complex questions about the nature of the process. By fitting modified models consistent with such questions, we should gain a better insight into the earthquake process. Hence, we consider a sequence of incrementally modified ETAS type models rather than `the' ETAS model.

  7. Slim Discs with Varying Accretion Rates

    Institute of Scientific and Technical Information of China (English)

    JIAO Cheng-Liang; LU Ju-Fu

    2009-01-01

    @@ It was revealed in our previous studies that there exists a maximal possible accretion rate for slim discs with constant accretion rates because the correctly calculated vertical gravitational force can only gather some limited amount of accreted matter. Here we show that when the accretion rate is not constant and instead decreases with decreasing radius because of outflows, such that the amount of accreted matter is adjusted to be within the allowed limit, global slim disc solutions can be constructed even for the case that accretion rates at large radii apparently exceed the maximal possible value. This result further demonstrates that outflows seem to be unavoidable for accretion flows with large accretion rates at large radii.

  8. Petri nets extension to model state-varying failure rates

    DEFF Research Database (Denmark)

    Lazarova-Molnar, Sanja

    2013-01-01

    One of the most common assumptions in reliability modeling is the constant failure rate. This has been increasingly changing lately, yielding significant research towards abandoning simulation results based on this assumption; thus, deeming constant failure rates as inadequate to model failures......-varying failure rates and extend the formalism of Petri nets to model them. To illustrate our approach we provide an example model that features state-varying failure rates....

  9. Calving rates at tidewater glaciers vary strongly with ocean temperature

    Science.gov (United States)

    Luckman, Adrian; Benn, Douglas I.; Cottier, Finlo; Bevan, Suzanne; Nilsen, Frank; Inall, Mark

    2015-10-01

    Rates of ice mass loss at the calving margins of tidewater glaciers (frontal ablation rates) are a key uncertainty in sea level rise projections. Measurements are difficult because mass lost is replaced by ice flow at variable rates, and frontal ablation incorporates sub-aerial calving, and submarine melt and calving. Here we derive frontal ablation rates for three dynamically contrasting glaciers in Svalbard from an unusually dense series of satellite images. We combine ocean data, ice-front position and terminus velocity to investigate controls on frontal ablation. We find that frontal ablation is not dependent on ice dynamics, nor reduced by glacier surface freeze-up, but varies strongly with sub-surface water temperature. We conclude that calving proceeds by melt undercutting and ice-front collapse, a process that may dominate frontal ablation where submarine melt can outpace ice flow. Our findings illustrate the potential for deriving simple models of tidewater glacier response to oceanographic forcing.

  10. Re-operation for parotid gland cancer following non-standard surgical treatment

    Institute of Scientific and Technical Information of China (English)

    Xiangmin Zhang; Xiaolin Lan; Lianbin Liu; Rong Li; Fufu Xiao; Folin Liu

    2012-01-01

    Objective: The purpose of this study was to analyze the clinical disadvantages of non-standard surgical treatment for parotid gland cancer and probe the re-operative indication following non-standard surgical treatment.Methods: Data of 58 cases suffered parotid gland cancer who received non-standard operation at other hospital and received re-operation in tumor hospital of Ganzhou from June 1998 to October 2010 were retrospectively reviewed.Results: In all cases, parotid gland cancer were residual in 46 cases, the facial nerve remaining rate was 81.0% (47/58), facial nerve branches injury rate was 3.5% (2/58), facial nerve partial resection rate was 8.6% (5/58) and total resection rate was 6.9% (4/58).The sensitivity of residual tumor was 83.3%, scanned by contrast-enhanced CT and the CT positive predictive value was 86.9%.Conclusion: Consideration of the higher residual tumor rate in patients who received non-standard operations, the re-operations were necessary.Contrast-enhanced CT positive predictive value was high for residual tumor and it was important for re-operation.

  11. Accidental falls involving medical implant re-operation.

    Science.gov (United States)

    Ong, Kevin L; Lau, Edmund; Moore, Tara; Heller, Michelle F

    2009-10-01

    Implantation of medical devices is becoming more prevalent, and as a result, a greater number of patients who fall accidentally are expected to have a medical implant. The Nationwide Inpatient Sample (NIS) was used to evaluate hospital admissions following accidental falls involving re-operation of existing medical implants (hip, knee, spine, and fracture fixation) from 1990 to 2005. From 1990 to 2005, hospitalisations due to accidental falls on level surfaces increased by 306%, and hospitalisations due to falls from stairs increased by 310%. Falls involving orthopaedic revision surgery (re-operation) are relatively rare, but the incidence has increased by approximately 35%. Hospital stays after falls on level surfaces involving re-operation were 1.0 day (median) longer and cost 50% (median) more than those that did not involve re-operation in 2005. After staircase falls, hospital stays for patients undergoing re-operations were 2.0 days (median) longer and cost 108% (median) more. The greater hospital costs and hospital stay for patients needing re-operations indicate that additional medical treatment was required.

  12. Surgical operation and re-operation for hepatocellular carcinoma with bile duct thrombosis

    Institute of Scientific and Technical Information of China (English)

    WANG Ya-dong; XUE Huan-zhou; JIANG Qing-feng; SHEN Quan; WANG Lian-cai; ZHANG Xiao; LU Bing; YU Miao; LI Ke

    2010-01-01

    Background Few reports have evaluated the efficacy of re-operation for relapse after initial surgery for hepatocellular carcinoma (HCC) with bile duct thrombosis (BDT).The aim of this study was to investigate the efficacy of initial surgery and subsequent re-operation for HCC with BDT, and their effects on prognosis.Methods The clinical data of 880 patients with HCC, including 28 patients with BDT, who underwent radical hepatectomy between 1998 and 2008 in our hospital, were reviewed.The effects of BDT and re-operation on prognosis were retrospectively analyzed.Results The 1-, 3- and 5-year survival rates were 89.3%, 46.4% and 21.4%, respectively, in 28 patients with BDT versus 91.4%, 52.9% and 20.9% in 852 patients without BDT (P >0.05).Six patients with BDT underwent re-operation after disease relapse, and their survival time was significantly longer than those who did not undergo re-operation (P <0.05).Multivariate analysis indicated that portal vein invasion and tumor size were independently associated with tumor relapse and prognosis (P<0.05).Univariate analysis and multivariate analyses showed that obstructive jaundice was not significantly correlated with tumor relapse or prognosis (P >0.05).Conclusions Hepatectomy plus BDT removal is an effective treatment option for HCC with BDT.Obstructive jaundice is not a contraindication for surgery.Re-operation after relapse can provide good outcomes if the cases are appropriately selected.

  13. Home visits: why do rates vary so much?

    LENUS (Irish Health Repository)

    Stewart, P

    2012-03-01

    Data including information on patient age, gender, who initiated the visit and call classification was collected during office hours from 12 G.P. rural teaching practices with a combined GMS patient population of 24,720, over a 2 month period. There were a total of 603 home visits, giving an annual visiting rate of 143\\/1000. Visiting rates varied between practices from 45 to 305\\/1000 per year. When high visiting practices (>210\\/1000\\/year) were compared to low visiting rate practices (>90\\/1000\\/year), patients tended to be older (79.7 v. 74.5 years) and calls were 12 times more likely to be doctor initiated (16.6% v. 1.4%) or classified as routine( 50.7% v. 44.9%). The variation between practices was related in part to patient age but appears largely due to differences in doctor home visiting behaviour. There are no recent figures on home visiting in Ireland.

  14. Predictors of re-operation due to post-surgical bleeding in breast cancer patients

    DEFF Research Database (Denmark)

    Lietzen, Lone Winther; Cronin-Fenton, D; Garne, J P

    2012-01-01

    To assess the risk of re-operation due to post-surgical bleeding after initial breast cancer surgery and to identify predictors of re-operation.......To assess the risk of re-operation due to post-surgical bleeding after initial breast cancer surgery and to identify predictors of re-operation....

  15. Dressed to Present: Ratings of Classroom Presentations Vary with Attire

    Science.gov (United States)

    Gurung, Regan A. R.; Kempen, Laura; Klemm, Kayla; Senn, Rebecca; Wysocki, Rosie

    2014-01-01

    This study investigates the effects of formality of dress on ratings of classroom presentations. Participants (N = 65, 66% women) from a Midwestern university in the United States rated three female students giving a presentation designed for a health psychology class in one of four outfits: casual, party, business casual, or business formal.…

  16. Peanut canopy temperature and NDVI response to varying irrigation rates

    Science.gov (United States)

    Variable rate irrigation (VRI) systems have the potential to conserve water by spatially allocating limited water resources. In this study, peanut was grown under a VRI system to evaluate the impact of differential irrigation rates on peanut yield. Additionally, we evaluated the impact of differenti...

  17. THE IMPLICATIONS OF VARYING EXCHANGE RATES FOR THE INTERNATIONAL TRADE

    OpenAIRE

    Sandu Carmen

    2011-01-01

    The benefit of international trade is a more efficient employment of the productive forces of the world. (John Stuart Mill) The exchange rate is a primary factor that influences economy. This instrument is used by some countries in order to improve the lack of balance caused as a result of the financial crisis felt in many countries considered by then infallible. The negative effects of the financial crisis can also be found in the decreased volume of commodities involved in international tra...

  18. THE IMPLICATIONS OF VARYING EXCHANGE RATES FOR THE INTERNATIONAL TRADE

    Directory of Open Access Journals (Sweden)

    Sandu Carmen

    2011-07-01

    Full Text Available The benefit of international trade is a more efficient employment of the productive forces of the world. (John Stuart Mill The exchange rate is a primary factor that influences economy. This instrument is used by some countries in order to improve the lack of balance caused as a result of the financial crisis felt in many countries considered by then infallible. The negative effects of the financial crisis can also be found in the decreased volume of commodities involved in international trade exchanges, as a consequence of modified prices and decreased offer. The globalizing trend leads to a constant expansion of exchanges between countries and to the consolidation of international cooperation. Except that economic interdependence generates an increased risk under the influence of economic, financial, monetary or political factors. The currency risk can generate either a gain or loss during foreign trade operations. The long period of RON depreciation made possible the entry of Romanian products on the international markets due to their prices. Sheltered by the gain generated by the evolution of the exchange rate, most of the exporters were not concerned by the increase of product competitiveness or by avoiding the currency risk. The fact that, for many years, the evolution of the exchange rate generated substantial losses for the exporters shows that risk coverage in Romania is, in most cases, a purely theoretical concept.

  19. Surgical strategies of re-operation for non-anastomotic biliary duct stricture after liver transplantation

    Directory of Open Access Journals (Sweden)

    Shao-ping WANG

    2015-10-01

    Full Text Available Objective To investigate the re-operation timing and surgical modality for non-anastomotic biliary stricture (NABS after orthotopic liver transplantation (OLT. Methods The clinical data of 14 NABS patients hospitalized in our center from August 2003 to April 2014 were analyzed retrospectively. The patients were treated with different modalities of re-operation according to cholangiographic results, and the outcomes of re-operation were noted by postoperative follow-up. Results Among 421 OLT patients, NABS was seen in 14 (3.3%, 14/421, and it was accompanied by stenosis of hepatic artery in 4. Their total bilirubin, ALP and r-GGT levels were significantly higher in NABS patients than in non-NABS patients (P<0.01. According to cholangiographic findings, NABS was divided into 3 types: hepatic bile duct strictures (4 patients, type Ⅰ, multiple extrahepatic and intrahepatic biliary strictures (8 patients, type Ⅱ, intrahepatic biliary stricture (2 patients, type Ⅲ. The cure rate of interventional treatment in this study was 57.1% (8/14, and 6 patients eventually required surgical treatment again. The type Ⅰ patient was treated with Roux-en-Y anastomosis, and re-transplantation for other 5 patients (type Ⅱ in 4 and type Ⅲ in 1. Among these 5 patients receiving liver re-transplantation, 1 patient died of perioperative fungal infection. The blood loss (2570±851ml and operation time (492±173min in those re-transplantation patients were almost the same as their previous-transplantation (P> 0.05. More than half of type Ⅱ and Ⅲ patients needed re-transplantation, but the probability of re-transplantation was especially higher for those with hepatic artery stenosis (75%, 3/4. Cholangitis disappeared and the total bilirubin significantly reduced from 123.4µmol/L to 31.6µmol/L after resurgery. Conclusions For those NABS patients who may fail to be improved after a minimally invasive treatment, especially when it was combined with

  20. Volume dilatation in a polycarbonate blend at varying strain rates

    Science.gov (United States)

    Hiermaier, S.; Huberth, F.

    2012-05-01

    Impact loaded polymers show a variety of strain-rate dependent mechanical properties in their elastic, plastic and failure behaviour. In contrast to purely crystalline materials, the volume of polymeric materials can significantly change under irreversible deformations. In this paper, uni-axial tensile tests were performed in order to measure the dilatation in the Polycarbonate-Acrylnitril-Butadien-Styrol (PC-ABS) Bayblend T65. The accumulation of dilatation was measured at deformation speeds of 0.1 and 500 [ mm/ s]. Instrumented with a pair of two high-speed cameras, volume segments in the samples were observed. The change in volume was quantified as relation between the deformed and initial volumes of the segments. It was observed that the measured dilatations are of great significance for the constitutive models. This is specifically demonstrated through comparisons of stress-strain relations derived from the two camera-perspectives with isochoric relations based on single-surface observations of the same experiments.

  1. RELIABILITY ANALYSIS FOR A REPAIRABLE PARALLEL SYSTEM WITH TIME-VARYING FAILURE RATES

    Institute of Scientific and Technical Information of China (English)

    TangShengdao; WangFengquan

    2005-01-01

    To solve a real problem :how to calculate the reliability of a system with time-varying failure rates in industry systems,this paper studies a model for the load-sharing parallel system with time-varying failure rates,and obtains calculating formulas of reliability and availability of the system by solving differential equations. In this paper, the failure rates are expressed in polynomial configuration. The constant,linear and Weibull failure rate are in their special form. The polynomial failure rates provide flexibility in modeling the practical time-varying failure rates.

  2. Re-admissions, re-operations and length of stay in hospital after aseptic revision knee replacement in Denmark

    DEFF Research Database (Denmark)

    Lindberg-Larsen, M.; Jørgensen, C. C.; Hansen, Torben Bæk

    2014-01-01

    of hospital stay was four days (interquartile range: 3 to 5), with a 90 days re-admission rate of 9.9%, re-operation rate of 3.5% and mortality rate of 0.2%. The age ranges of 51 to 55 years (p = 0.018), 76 to 80 years (p ...-admission. The age ranges of 76 to 80 years (p = 0.018) and the large partial revision subgroup (p = 0.073) were related to an increased risk of re-operation. The ages from 76 to 80 years (p 120 min (p hospital stay...... that a length of hospital stay ≤ four days and discharge home at that time is safe following aseptic knee revision surgery in Denmark....

  3. Analysis of Heart Rate Variability Using Time-Varying Filtering of Heart Transplanted Patients

    OpenAIRE

    Laouini, Ghailen; Meste, Olivier; Meo, Marianna

    2012-01-01

    International audience; In this paper, we analyze the heart rate variability (HRV), obtained by using the time-varying integral pulse frequency modulation (TVIPFM) which is well adapted to the exercise stress testing. We consider that the mean heart period is varying function of time, during exercise. This technique allows the estimation of the autonomic nervous system modulation (ANS) from the beat occurrences. The estimated respiratory sinus arrhythmia is then filtered in the time-frequency...

  4. Evaluation of 118 Thyroid Cancer Patients Who Underwent a Re-operation after Local Resection

    Institute of Scientific and Technical Information of China (English)

    Jianping Hang; Dong Meng; Liqi Li

    2005-01-01

    OBJECTIVE To evaluate the incidence of residual thyroid cancer and cervical lymph node metastasis following a previous local resection for thyroid cancer, and to discuss methods of a reoperation.METHODS From 1994~2005, 118 patients with thyroid cancer who had previously been treated with a nodule-resection or subtotal Iobectomy in other hospitals underwent a surgical re-operation.RESULTS The incidence of residual cancer at the primary site was 38.1%. The lymph node metastasis rate at the central area was 39.8%.The rate of lymph node metastasis in patients with enlarged lymph nodes in the ipsilateral internal jugular chain was 37.5%. The rate of laryngeal recurrent nerve injury was 15.2% in other hospitals while that of the second operation in our hospital was 1.6%.CONCLUSION Nodule-resection or subtotal Iobectomy alone is not indicated for patients with thyroid cancer because of the high rate of local residual cancer. It is important to be familiar with the anatomy of the laryngeal recurrent nerve for thyroid surgery. Exploration to the central area is necessary for differentiated thyroid cancer.

  5. Hydrodynamic mean-field solutions of 1D exclusion processes with spatially varying hopping rates

    Science.gov (United States)

    Lakatos, Greg; O'Brien, John; Chou, Tom

    2006-03-01

    We analyse the open boundary partially asymmetric exclusion process with smoothly varying internal hopping rates in the infinite-size, mean-field limit. The mean-field equations for particle densities are written in terms of Ricatti equations with the steady-state current J as a parameter. These equations are solved both analytically and numerically. Upon imposing the boundary conditions set by the injection and extraction rates, the currents J are found self-consistently. We find a number of cases where analytic solutions can be found exactly or approximated. Results for J from asymptotic analyses for slowly varying hopping rates agree extremely well with those from extensive Monte Carlo simulations, suggesting that mean-field currents asymptotically approach the exact currents in the hydrodynamic limit, as the hopping rates vary slowly over the lattice. If the forward hopping rate is greater than or less than the backward hopping rate throughout the entire chain, the three standard steady-state phases are preserved. Our analysis reveals the sensitivity of the current to the relative phase between the forward and backward hopping rate functions.

  6. Hydrodynamic mean-field solutions of 1D exclusion processes with spatially varying hopping rates

    Energy Technology Data Exchange (ETDEWEB)

    Lakatos, Greg; O' Brien, John; Chou, Tom [Department of Biomathematics and Institute for Pure and Applied Mathematics, UCLA, Los Angeles, CA 90095 (United States)

    2006-03-10

    We analyse the open boundary partially asymmetric exclusion process with smoothly varying internal hopping rates in the infinite-size, mean-field limit. The mean-field equations for particle densities are written in terms of Ricatti equations with the steady-state current J as a parameter. These equations are solved both analytically and numerically. Upon imposing the boundary conditions set by the injection and extraction rates, the currents J are found self-consistently. We find a number of cases where analytic solutions can be found exactly or approximated. Results for J from asymptotic analyses for slowly varying hopping rates agree extremely well with those from extensive Monte Carlo simulations, suggesting that mean-field currents asymptotically approach the exact currents in the hydrodynamic limit, as the hopping rates vary slowly over the lattice. If the forward hopping rate is greater than or less than the backward hopping rate throughout the entire chain, the three standard steady-state phases are preserved. Our analysis reveals the sensitivity of the current to the relative phase between the forward and backward hopping rate functions.

  7. The control of self-propelled microjets inside a microchannel with time-varying flow rates

    NARCIS (Netherlands)

    Khalil, Islam S.M.; Magdanz, Veronika; Sanchez, Samuel; Schmidt, Oliver S.; Misra, Sarthak

    2013-01-01

    We demonstrate the closed-loop motion control of self-propelled microjets inside a fluidic microchannel. The motion control of the microjets is achieved in hydrogen peroxide solution with time-varying flow rates, under the influence of the controlled magnetic fields and the self-propulsion force. Ma

  8. Cesarean Delivery Rates Vary 10-Fold Among US Hospitals; Reducing Variation May Address Quality, Cost Issues

    Science.gov (United States)

    Kozhimannil, Katy Backes; Law, Michael R.; Virnig, Beth A.

    2013-01-01

    Cesarean delivery is the most commonly performed surgical procedure in the United States, and cesarean rates are increasing. Working with 2009 data from 593 US hospitals nationwide, we found that cesarean rates varied tenfold across hospitals, from 7.1 percent to 69.9 percent. Even for women with lower-risk pregnancies, in which more limited variation might be expected, cesarean rates varied fifteen-fold, from 2.4 percent to 36.5 percent. Thus, vast differences in practice patterns are likely to be driving the costly overuse of cesarean delivery in many US hospitals. Because Medicaid pays for nearly half of US births, government efforts to decrease variation are warranted. We focus on four promising directions for reducing these variations, including better coordination of maternity care, more data collection and measurement, tying Medicaid payment to quality improvement, and enhancing patient-centered decision making through public reporting. PMID:23459732

  9. A time-varying parameter VAR investigation of the exchange rate pass-through in Turkey

    Directory of Open Access Journals (Sweden)

    Çatık Abdurrahman Nazif

    2016-01-01

    Full Text Available The effects of exchange rate movements on price levels have important implications to macroeconomic policies through the impacts on trade balance and inflation. In contrast to previous studies, we employ a VAR model with time-varying parameters to measure the magnitude of exchange rate pass-through (ERPT. The findings confirm the time-varying pattern in the ERPT, as the magnitude of ERPT has reached its maximum value during the 1994 financial crisis. The decline in the magnitude of ERPT has become more pronounced after the 2001 financial crisis as a result of the implementation of inflation targeting, which has shifted Turkey’s economy from a long lasting high inflationary phase to a low inflationary economic environment.

  10. Structure/property relations of aluminum under varying rates and stress states

    Energy Technology Data Exchange (ETDEWEB)

    Tucker, Matthew T [Los Alamos National Laboratory; Horstemeyer, Mark F [MISSISSIPPI STATE UNIV; Whittington, Wilburn R [MISSISSIPPI STATE UNIV; Solanki, Kiran N [MISSISSIPPI STATE UNIV.

    2010-11-19

    In this work we analyze the plasticity, damage, and fracture characteristics of three different processed aluminum alloys (rolled 5083-H13, cast A356-T6, and extruded 6061-T6) under varying stress states (tension, compression, and torsion) and strain rates (0.001/, 1/s., and 1000/s). The stress state difference had more of a flow stress effect than the applied strain rates for those given in this study (0.001/sec up to 1000/sec). The stress state and strain rate also had a profound effect on the damage evolution of each aluminum alloy. Tension and torsional straining gave much greater damage nucleation rates than compression. Although the damage of all three alloys was found to be void nucleation dominated, the A356-T6 and 5083-H131 aluminum alloys incurred void damage via micron scale particles where the 6061-T6 aluminum alloy incurred void damage from two scales, micron-scale particles and nanoscale precipitates. Having two length scales of particles that participated in the damage evolution made the 6061-T6 incur a strain rate sensitive damage rate that was different than the other two aluminum alloys. Under tension, as the strain rate increased, the 6061-T6 aluminum alloy's void nucleation rate decreased, but the A356-T6 and 5083-H131 aluminum alloys void nucleation rate increased.

  11. Effect of varying heart rate on intra-ventricular filling fluid dynamics

    Science.gov (United States)

    Santhanakrishnan, Arvind; Okafor, Ikechukwu; Angirish, Yagna; Yoganathan, Ajit

    2013-11-01

    Impaired exercise tolerance is used to delineate asymptomatic patients during the clinical diagnosis of diastolic left heart failure. Examining the effects of varying heart rate on intra-ventricular filling can provide a physical understanding of the specific flow characteristics that are impacted during exercise. In this study, diastolic filling was investigated with an anatomical left ventricle (LV) physical model under normal heart rate of 70 bpm, and varying exercise conditions of 100 bpm and 120 bpm. The LV model was incorporated into a flow loop and tuned for physiological inflow rates and outflow pressures. 2D PIV measurements were conducted along 3 parallel longitudinal planes. The systemic pressure was maintained the same across all test conditions. The E/A ratio was maintained within 1.0-1.2 across all heart rates. The strength of the mitral vortex ring formed during E-wave, as well as the peak incoming jet velocity, decreased with increasing heart rate. During peak flow of the A-wave, the vortex ring propagated farther into the LV for 120 bpm as compared to 70 bpm. The results point to the heightened role of the atrial kick for optimal LV filling during exercise conditions. This study was funded by a grant from the National Heart, Lung and Blood Institute (RO1HL70262).

  12. The Oil Price and Exchange Rate Relationship Revisited: A time-varying VAR parameter approach

    Directory of Open Access Journals (Sweden)

    Vincent Brémond

    2016-07-01

    Full Text Available The aim of this paper is to study the relationship between the effective exchange rate of the dollar and the oil price dynamics from 1976 to 2013. We explore the links between financial factors (exchange rate, monetary policy, international liquidity and the oil price volatility. Using a Bayesian time-varying parameter vector auto-regressive estimation we demonstrate that the “historical coincidence” of oil and financial crises can be explained by the specificities of the relationship between these two commodities. The results of this paper are twofold. The US Dollar effective exchange rate elasticity of crude oil prices is not constant across time and remains negative from 1989: a depreciation of the effective exchange rate of the dollar triggers an increase of crude oil prices. This paper also demonstrates the contagion of financial commodities markets development upon the global economy.

  13. Studies on Composite Extrudable Propellant with varied Burning Rate Pressure Index 'n'

    Directory of Open Access Journals (Sweden)

    T. L. Varghese

    1989-01-01

    Full Text Available This paper discusses the development of composite propellantextrusion technique and the study of burning rate pressure indices nwith respect to compositional variations. The n is found to vary from0.35 to plateau and plateau to mesa by suitable compositionalmodifications. Compositional influence on burning rate with specificreference to plateau and mesaburning additives is described. Detailsof the process parameters like fluidity of the slurry, extrusion pressure,extrusion rate and die-swell are presented. This propellant is based onISRO-CTPB binder using ISRO-AP as oxidizer. Ammonium perchlorate (AP particle size variation and inclusion of additives likePVC, lead stearate, ammonium sulphate, lithium fluoride etc. are foundto influence the burning rate pressure index n.

  14. Tuning of Heat Transfer Rate of Cobalt Manganese Ferrite Based Magnetic Fluids in Varying Magnetic Field

    Directory of Open Access Journals (Sweden)

    Margabandhu MARIMUTHU

    2017-08-01

    Full Text Available Magnetic fluids are the colloidal solutions containing suspended magnetic nanoparticles in carrier fluids. The present work analyzed the heat transfer characteristics of de-ionized water and transformer oil (base fluids based cobalt manganese ferrite (Co1-xMnxFe2O4 coated with oleic acid synthesized via co-precipitation technique magnetic fluids in  varying magnetic field. Experimental investigations were carried out to analyze the heat transfer property of synthesized magnetic fluids (MNF in varying magnetic field applied in perpendicular direction to the thermal gradient of magnetic fluids. The experimental results indicate that the magnetic fluids show enhancement in heat transfer rate than carrier fluids in absence of magnetic field and it shows decrement in heat transfer rate in presence of varying magnetic field. Thus, the results reveal that the heat transfer characteristics of cobalt manganese ferrite based magnetic fluids was tunable by controlling the direction and influence of magnetic field strength. This tunable heat transfer property of cobalt manganese ferrite based magnetic fluids could be applicable in heat transport phenomena of transformers and in microelectronic devices.DOI: http://dx.doi.org/10.5755/j01.ms.23.3.16662

  15. What can we get from varying scan rate in protein differential scanning calorimetry?

    Science.gov (United States)

    Amani, Mojtaba; Moosavi-Movahedi, Ali A; Kurganov, Boris I

    2017-06-01

    Differential scanning calorimetry has many advantages over other techniques to study the thermal stability of proteins due to its direct measurement of thermodynamic parameters. Most proteins undergo irreversible thermal denaturation causing their thermogram to be scan rate dependent. We modeled reversible and irreversible protein thermograms at varying scan rates. The complete Lumry-Eyring model was used to model the irreversible thermograms at various values of T1/2 (temperature at which equilibrium constant equals unity) and T* (temperature at which rate constant equals 1min(-1)). Our results have shown that the thermal effects of two processes are integrated with decreasing the T* relative to T1/2. It is also shown that the shape of second derivatives of thermograms under different conditions have specific pattern which can be used to judge and estimate the correct model for protein denaturation. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Dynamic linear models to explore time-varying suspended sediment-discharge rating curves

    Science.gov (United States)

    Ahn, Kuk-Hyun; Yellen, Brian; Steinschneider, Scott

    2017-06-01

    This study presents a new method to examine long-term dynamics in sediment yield using time-varying sediment-discharge rating curves. Dynamic linear models (DLMs) are introduced as a time series filter that can assess how the relationship between streamflow and sediment concentration or load changes over time in response to a wide variety of natural and anthropogenic watershed disturbances or long-term changes. The filter operates by updating parameter values using a recursive Bayesian design that responds to 1 day-ahead forecast errors while also accounting for observational noise. The estimated time series of rating curve parameters can then be used to diagnose multiscale (daily-decadal) variability in sediment yield after accounting for fluctuations in streamflow. The technique is applied in a case study examining changes in turbidity load, a proxy for sediment load, in the Esopus Creek watershed, part of the New York City drinking water supply system. The results show that turbidity load exhibits a complex array of variability across time scales. The DLM highlights flood event-driven positive hysteresis, where turbidity load remained elevated for months after large flood events, as a major component of dynamic behavior in the rating curve relationship. The DLM also produces more accurate 1 day-ahead loading forecasts compared to other static and time-varying rating curve methods. The results suggest that DLMs provide a useful tool for diagnosing changes in sediment-discharge relationships over time and may help identify variability in sediment concentrations and loads that can be used to inform dynamic water quality management.

  17. Plurifinely Plurisubharmonic Functions and the Monge Ampère Operator

    NARCIS (Netherlands)

    El Kadiri, M.; Wiegerinck, J.

    2014-01-01

    We will define the Monge-Ampère operator on finite (weakly) plurifinely plurisubharmonic functions in plurifinely open sets U ⊂ ℂ n and show that it defines a positive measure. Ingredients of the proof include a direct proof for bounded strongly plurifinely plurisubharmonic functions, which is based

  18. Prediction and dissection of widely-varying association rate constants of actin-binding proteins.

    Directory of Open Access Journals (Sweden)

    Xiaodong Pang

    Full Text Available Actin is an abundant protein that constitutes a main component of the eukaryotic cytoskeleton. Its polymerization and depolymerization are regulated by a variety of actin-binding proteins. Their functions range from nucleation of actin polymerization to sequestering G-actin in 1∶1 complexes. The kinetics of forming these complexes, with rate constants varying at least three orders of magnitude, is critical to the distinct regulatory functions. Previously we have developed a transient-complex theory for computing protein association mechanisms and association rate constants. The transient complex refers to an intermediate in which the two associating proteins have near-native separation and relative orientation but have yet to form short-range specific interactions of the native complex. The association rate constant is predicted as k(a = k(a0 e(-ΔG(el*/k(BT, where k(a0 is the basal rate constant for reaching the transient complex by free diffusion, and the Boltzmann factor captures the bias of long-range electrostatic interactions. Here we applied the transient-complex theory to study the association kinetics of seven actin-binding proteins with G-actin. These proteins exhibit three classes of association mechanisms, due to their different molecular shapes and flexibility. The 1000-fold k(a variations among them can mostly be attributed to disparate electrostatic contributions. The basal rate constants also showed variations, resulting from the different shapes and sizes of the interfaces formed by the seven actin-binding proteins with G-actin. This study demonstrates the various ways that actin-binding proteins use physical properties to tune their association mechanisms and rate constants to suit distinct regulatory functions.

  19. Robust and Optimal Control of Magnetic Microparticles inside Fluidic Channels with Time-Varying Flow Rates

    Directory of Open Access Journals (Sweden)

    Islam S.M. Khalil

    2016-06-01

    Full Text Available Targeted therapy using magnetic microparticles and nanoparticles has the potential to mitigate the negative side-effects associated with conventional medical treatment. Major technological challenges still need to be addressed in order to translate these particles into in vivo applications. For example, magnetic particles need to be navigated controllably in vessels against flowing streams of body fluid. This paper describes the motion control of paramagnetic microparticles in the flowing streams of fluidic channels with time-varying flow rates (maximum flow is 35 ml.hr−1. This control is designed using a magnetic-based proportional-derivative (PD control system to compensate for the time-varying flow inside the channels (with width and depth of 2 mm and 1.5 mm, respectively. First, we achieve point-to-point motion control against and along flow rates of 4 ml.hr−1, 6 ml.hr−1, 17 ml.hr−1, and 35 ml.hr−1. The average speeds of single microparticle (with average diameter of 100 μm against flow rates of 6 ml.hr−1 and 30 ml.hr−1 are calculated to be 45 μm.s−1 and 15 μm.s−1, respectively. Second, we implement PD control with disturbance estimation and compensation. This control decreases the steady-state error by 50%, 70%, 73%, and 78% at flow rates of 4 ml.hr−1, 6 ml.hr−1, 17 ml.hr−1, and 35 ml.hr−1, respectively. Finally, we consider the problem of finding the optimal path (minimal kinetic energy between two points using calculus of variation, against the mentioned flow rates. Not only do we find that an optimal path between two collinear points with the direction of maximum flow (middle of the fluidic channel decreases the rise time of the microparticles, but we also decrease the input current that is supplied to the electromagnetic coils by minimizing the kinetic energy of the microparticles, compared to a PD control with disturbance compensation.

  20. Robust and Optimal Control of Magnetic Microparticles Inside Fluidic Channels with Time-varying Flow Rates

    Directory of Open Access Journals (Sweden)

    Islam S.M. Khalil

    2016-06-01

    Full Text Available Targeted therapy using magnetic microparticles and nanoparticles has the potential to mitigate the negative side-effects associated with conventional medical treatment. Major technological challenges still need to be addressed in order to translate these particles into in vivo applications. For example, magnetic particles need to be navigated controllably in vessels against flowing streams of body fluid. This paper describes the motion control of paramagnetic microparticles in the flowing streams of fluidic channels with time-varying flow rates (maximum flow is 35 ml.hr-1. This control is designed using a magnetic-based proportional-derivative (PD control system to compensate for the time-varying flow inside the channels (with width and depth of 2 mm and 1.5 mm, respectively. First, we achieve point-to-point motion control against and along flow rates of 4 ml.hr-1, 6 ml.hr-1, 17 ml.hr-1, and 35 ml.hr-1. The average speeds of single microparticle (with average diameter of 100 μm against flow rates of 6 ml.hr-1 and 30 ml.hr-1 are calculated to be 45 μm.s-1 and 15 μm.s-1, respectively. Second, we implement PD control with disturbance estimation and compensation. This control decreases the steady-state error by 50%, 70%, 73%, and 78% at flow rates of 4 ml.hr-1, 6 ml.hr-1, 17 ml.hr-1, and 35 ml.hr-1, respectively. Finally, we consider the problem of finding the optimal path (minimal kinetic energy between two points using calculus of variation, against the mentioned flow rates. Not only do we find that an optimal path between two collinear points with the direction of maximum flow (middle of the fluidic channel decreases the rise time of the microparticles, but we also decrease the input current that is supplied to the electromagnetic coils by minimizing the kinetic energy of the microparticles, compared to a PD control with disturbance compensation.

  1. Spatially varying predictors of teenage birth rates among counties in the United States

    Directory of Open Access Journals (Sweden)

    Carla Shoff

    2012-09-01

    Full Text Available BACKGROUND Limited information is available about teenage pregnancy and childbearing in rural areas, even though approximately 20 percent of the nation's youth live in rural areas. Identifying whether there are differences in the teenage birth rate (TBR across metropolitan and nonmetropolitan areas is important because these differences may reflect modifiable ecological-level influences such as education, employment, laws, healthcare infrastructure, and policies that could potentially reduce the TBR. OBJECTIVE The goals of this study are to investigate whether there are spatially varying relationships between the TBR and the independent variables, and if so, whether these associations differ between metropolitan and nonmetropolitan counties. METHODS We explore the heterogeneity within metropolitan/nonmetropolitan county groups separately using geographically weighted regression (GWR, and investigate the difference between metropolitan/nonmetropolitan counties using spatial regime models with spatial errors. These analyses were applied to county-level data from the National Center for Health Statistics and the US Census Bureau. RESULTS GWR results suggested that non-stationarity exists in the associations between TBR and determinants within metropolitan/nonmetropolitan groups. The spatial regime analysis indicated that the effect of socioeconomic disadvantage on TBR significantly varied by the metropolitan status of counties. CONCLUSIONS While the spatially varying relationships between the TBR and independent variables were found within each metropolitan status of counties, only the magnitude of the impact of the socioeconomic disadvantage index is significantly stronger among metropolitan counties than nonmetropolitan counties. Our findings suggested that place-specific policies for the disadvantaged groups in a county could be implemented to reduce TBR in the US.

  2. Performance of the experimental resins and dental nanocomposites at varying deformation rates.

    Science.gov (United States)

    Kumar, Naresh; Shortall, Adrian

    2014-08-01

    The aim of the present study was to evaluate the bi-axial flexural strength of experimental unfilled resins and resin-based composites at varying deformation rates following 1-week dry, 1-week wet, and 13-week wet storage regimes. A total of 270 disc-shaped specimens (12 mm diameter, 1 mm thickness) of either unfilled resins or experimental resin-based composites comprising of three groups (n = 90) were fabricated. Three groups of each unfilled resin and resin-based composites (n = 90) were stored for 1 week under dry conditions, and at 1 and 13 weeks under wet conditions (37 ± 1°C) before testing. The bi-axial flexural strength of each unfilled resin and resin-based composites group was determined at a 0.1, 1, and 10 mm/min deformation rate (n = 30). The unfilled resins revealed a deformation rate dependence following all storage regimes; however, the addition of fillers in the unfilled resins modified such reliance following the 1-week dry and 13-week wet storage regimes. In contrast, a lower bi-axial flexural strength of the 1-week wet resin-based composites specimens at a 0.1 mm/min deformation rate was identified. A lower bi-axial flexural strength of the 1-week wet resin-based composites specimens at a low deformation rate suggests that premature failure of resin-based composites restorations might occur in patients with parafunctional habits, such as bruxism. © 2013 Wiley Publishing Asia Pty Ltd.

  3. A Time-Varying Parameter Vector Autoregression Model for Forecasting Emerging Market Exchange Rates

    Directory of Open Access Journals (Sweden)

    Manish Kumar

    2010-12-01

    Full Text Available In this study, a vector autoregression (VAR model with time-varying parameters (TVP to predict the daily Indian rupee (INR/US dollar (USD exchange rates for the Indian economy is developed. The method is based on characterization of the TVP as an optimal control problem. The methodology is a blend of the flexible least squares and Kalman filter techniques. The out-of-sample forecasting performance of the TVP-VAR model is evaluated against the simple VAR and ARIMA models, by employing a cross-validation process and metrics such as mean absolute error, root mean square error, and directional accuracy. Outof-sample results in terms of conventional forecast evaluation statistics and directional accuracy show TVP-VAR model consistently outperforms the simple VAR and ARIMA models.

  4. Threshold-Based Bit Error Rate for Stopping Iterative Turbo Decoding in a Varying SNR Environment

    Science.gov (United States)

    Mohamad, Roslina; Harun, Harlisya; Mokhtar, Makhfudzah; Adnan, Wan Azizun Wan; Dimyati, Kaharudin

    2017-01-01

    Online bit error rate (BER) estimation (OBE) has been used as a stopping iterative turbo decoding criterion. However, the stopping criteria only work at high signal-to-noise ratios (SNRs), and fail to have early termination at low SNRs, which contributes to an additional iteration number and an increase in computational complexity. The failure of the stopping criteria is caused by the unsuitable BER threshold, which is obtained by estimating the expected BER performance at high SNRs, and this threshold does not indicate the correct termination according to convergence and non-convergence outputs (CNCO). Hence, in this paper, the threshold computation based on the BER of CNCO is proposed for an OBE stopping criterion (OBEsc). From the results, OBEsc is capable of terminating early in a varying SNR environment. The optimum number of iterations achieved by the OBEsc allows huge savings in decoding iteration number and decreasing the delay of turbo iterative decoding.

  5. Match injury rates in professional soccer vary with match result, match venue, and type of competition.

    Science.gov (United States)

    Bengtsson, Håkan; Ekstrand, Jan; Waldén, Markus; Hägglund, Martin

    2013-07-01

    Player activities in soccer matches are influenced by the match result and match venue. It is not known whether injury rates are influenced by these factors. To investigate whether there are associations between injury rates and the match result, venue, and type of competition in male soccer. Cohort study; Level of evidence, 3. Twenty-six professional clubs from 10 countries were followed prospectively during 9 seasons (2001-2002 to 2009-2010). All matches, and injuries occurring in these matches, were registered by the team's medical staff. An injury was registered if it resulted in player absence from training or matches. Information about match result, venue, and type of competition for all reported matches was gathered by the authors from online databases. Injury rates in matches with varying match characteristics were compared by use of generalized estimating equations. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. A total of 2738 injuries during 6010 matches were registered. There were no associations between odds of 1 injury occurrence and match result or type of competition, whereas the odds were decreased in matches played away compared with home matches (OR, 0.89; 95% CI, 0.80-0.99). The odds of 2 or more injury occurrences in a match were increased in matches resulting in a draw (OR, 1.39; 95% CI, 1.15-1.69) or loss (OR, 1.66; 95% CI, 1.38-1.98) compared with matches won and were decreased in other cup matches compared with league matches (OR, 0.57; 95% CI, 0.39-0.84) and in matches played away compared with home matches (OR, 0.70; 95% CI, 0.60-0.82). Finally, injuries with more than 1 week's absence occurred more frequently in Champions League matches compared with league matches both for matches with 1 injury (OR, 1.26; 95% CI, 1.09-1.45) and matches with 2 or more injuries (OR, 1.57; 95% CI, 1.13-2.20). The odds of 2 or more injury occurrences in professional soccer were higher in matches resulting in a loss or a draw compared

  6. Performance of a weighing rain gauge under laboratory simulated time-varying reference rainfall rates

    Science.gov (United States)

    Colli, M.; Lanza, L. G.; La Barbera, P.

    2013-09-01

    The available calibration experiences about rain intensity gauges relying on the weighing measuring principle are based on laboratory tests performed under constant reference flow rate conditions. Although the Weighing Gauges (WG) do provide better performance than more traditional Tipping Bucket Rain Gauges (TBR) under constant reference flow rates, dynamic effects do impact on the accuracy of WG measurements under real-world/time-varying rainfall conditions. The most relevant biases are due to the response time of the measurement system and the derived systematic delay in assessing the exact weight of the volume of cumulated precipitation collected in the container. This delay assumes a relevant role in case high resolution rainfall intensity (RI) time series are sought from the instrument, as is the case of many hydrologic and meteo-climatic applications (the one-minute time resolution recommended by the WMO for rainfall intensity measurements is here assumed). A significant sampling error is also attributable to some kind of weighing gauge, which affects the low intensity range as well. A laboratory investigation of the accuracy and precision of a modern weighing gauge manufactured by OTT (Pluvio2) under unsteady-state reference RI conditions is here addressed. Three different laboratory test conditions are applied: single and double step variations of the reference flow rate and a simulated real-world event. The preliminary development and validation of a suitable rainfall simulator for the generation of time-variable reference intensities is presented. The generator is demonstrated to have a sufficiently short time response with respect to the expected instrument behavior in order to ensure effective comparison of the measured vs. reference intensities. The measurements obtained from the WG are compared with those derived from a traditional TBR (manufactured by Casella) under the same laboratory conditions. The TBR measurements have been corrected to account

  7. Do Attitudinal and Behavioral Ratings of Family Members Vary across Familial Configurations?

    Science.gov (United States)

    Parish, Thomas S.; Necessary, James R.

    1994-01-01

    Compared 212 high school students from different family structures regarding their descriptions of themselves and their parents. Found that fathers' ratings or evaluations, but not mothers' ratings or students' self-ratings, suffered in wake of divorce. Regarding perceived "loving" actions by parents, students from intact families had advantage…

  8. Transient Solution to an infinite Server Queue with Varying Arrival and Departure Rate

    Directory of Open Access Journals (Sweden)

    A. A. El-Sherbiny

    2010-01-01

    Full Text Available Problem statement: In many potential application of queueing theory, the transient solution of queueing system is important. Approach: This study presented the transient solution for infinite server queues with Poisson arrivals and exponential service times when the parameters of both distributions are allowed to vary with time. Based on generating functions technique which results in a simple differential equation. Using the properties of Bessel functions in the solution of this differential equation, the solution of an infinite server queues can be given in simple form. Results: The researcher obtained the transient solution an infinite server queues with Poisson arrivals and exponential service times when the parameters of both distributions are allowed to vary with time and prove that some past results are special case from his results. Conclusion: These results indicated that the probabilities can be extracted in a direct way.

  9. Mechanical behaviour of glass fibre reinforced composite at varying strain rates

    Science.gov (United States)

    Acharya, Saikat; Mondal, D. K.; Ghosh, K. S.; Mukhopadhyay, A. K.

    2017-03-01

    Here we report the results of compressive split Hopkinson pressure bar experiments (SHPB) conducted on unidirectional glass fibre reinforced polymer (GFRP) in the strain rate regime 5  ×  102–1.3  ×  103 s‑1. The maximum compressive strength of GFRP was found to increase by as much as 55% with increase in strain rate. However, the corresponding relative strain to failure response was measured to increase only marginally with increase in strain rates. Based on the experimental results and photomicrographs obtained from FE-SEM based post mortem examinations, the failure phenomena are suggested to be associated with increase in absorption of energy from low to high strain rates. Attempts have been made to explain these observations in terms of changes in deformation mechanisms primarily as a function of strain rates.

  10. Optimal harvesting of fish stocks under a time-varying discount rate

    OpenAIRE

    Duncan, Stephen; Hepburn, Cameron; Papachristodoulou, Antonis

    2010-01-01

    Abstract Optimal control theory has been extensively used to determine the optimal harvesting policy for renewable resources such as fish stocks. In such optimizations, it is common to maximise the discounted utility of harvesting over time, employing a constant time discount rate. However, evidence from human and animal behaviour suggests that we have evolved to employ discount rates which fall over time, often referred to as ?hyperbolic discounting?. This increases the weight on ...

  11. Controllable deterioration rate for time-dependent demand and time-varying holding cost

    Directory of Open Access Journals (Sweden)

    Mishra Vinod Kumar

    2014-01-01

    Full Text Available In this paper, we develop an inventory model for non-instantaneous deteriorating items under the consideration of the facts: deterioration rate can be controlled by using the preservation technology (PT during deteriorating period, and holding cost and demand rate both are linear function of time, which was treated as constant in most of the deteriorating inventory models. So in this paper, we developed a deterministic inventory model for non-instantaneous deteriorating items in which both demand rate and holding cost are a linear function of time, deterioration rate is constant, backlogging rate is variable and depend on the length of the next replenishment, shortages are allowed and partially backlogged. The model is solved analytically by minimizing the total cost of the inventory system. The model can be applied to optimizing the total inventory cost of non-instantaneous deteriorating items inventory for the business enterprises, where the preservation technology is used to control the deterioration rate, and demand & holding cost both are a linear function of time.

  12. Botanical and agronomic growth of two Panicum maximum cultivars, Mombasa and Tanzania, at varying sowing rates

    Directory of Open Access Journals (Sweden)

    Michael D. Hare

    2014-09-01

    Full Text Available A field trial in northeast Thailand during 2011–2013 compared the establishment and growth of 2 Panicum maximum cultivars, Mombasa and Tanzania, sown at seeding rates of 2, 4, 6, 8, 10 and 12 kg/ha. In the first 3 months of establishment, higher sowing rates produced significantly more DM than sowing at 2 kg/ha, but thereafter there were no significant differences in total DM production between sowing rates of 2–12 kg/ha. Lower sowing rates produced fewer tillers/m2 than higher sowing rates but these fewer tillers were significantly heavier than the more numerous smaller tillers produced by higher sowing rates. Mombasa produced 23% more DM than Tanzania in successive wet seasons (7,060 vs. 5,712 kg DM/ha from 16 June to 1 November 2011; and 16,433 vs. 13,350 kg DM/ha from 25 April to 24 October 2012. Both cultivars produced similar DM yields in the dry seasons (November–April, averaging 2,000 kg DM/ha in the first dry season and 1,750 kg DM/ha in the second dry season. Mombasa produced taller tillers (104 vs. 82 cm, longer leaves (60 vs. 47 cm, wider leaves (2 vs. 1.8 cm and heavier tillers (1 vs. 0.7 g than Tanzania but fewer tillers/m2 (260 vs. 304. If farmers improve soil preparation and place more emphasis on sowing techniques, there is potential to dramatically reduce seed costs.Keywords: Guinea grass, tillering, forage production, seeding rates, Thailand.DOI: 10.17138/TGFT(2246-253

  13. Thai Rate-Varied Vowel Length Perception and the Impact of Musical Experience.

    Science.gov (United States)

    Cooper, Angela; Wang, Yue; Ashley, Richard

    2017-03-01

    Musical experience has been demonstrated to play a significant role in the perception of non-native speech contrasts. The present study examined whether or not musical experience facilitated the normalization of speaking rate in the perception of non-native phonemic vowel length contrasts. Native English musicians and non-musicians (as well as native Thai control listeners) completed identification and AX (same-different) discrimination tasks with Thai vowels contrasting in phonemic length at three speaking rates. Results revealed facilitative effects of musical experience in the perception of Thai vowel length categories. Specifically, the English musicians patterned similarly to the native Thai listeners, demonstrating higher accuracy at identifying and discriminating between-category vowel length distinctions than at discriminating within-category durational differences due to speaking rate variations. The English musicians also outperformed non-musicians at between-category vowel length discriminations across speaking rates, indicating musicians' superiority in perceiving categorical phonemic length differences. These results suggest that musicians' attunement to rhythmic and temporal information in music transferred to facilitating their ability to normalize contextual quantitative variations (due to speaking rate) and perceive non-native temporal phonemic contrasts.

  14. Male chimpanzees' grooming rates vary by female age, parity, and fertility status

    DEFF Research Database (Denmark)

    Proctor, Darby P; Lambeth, Susan P; Schapiro, Steve;

    2011-01-01

    , should show little or no preference when choosing mating partners (e.g. should mate indiscriminately). To determine if the preferences indicated by copulations appear in other contexts as well as how they interact, we examined how male chimpanzees' grooming patterns varied amongst females. We found...... that males' preferences were based on interactions among females' fertility status, age, and parity. First, grooming increased with increasing female parity. We further found an effect of the estrous cycle on grooming; when females were at the lowest point of their cycle, males preferentially groomed parous...... females at peak reproductive age, but during maximal tumescence, males preferred the oldest multiparous females. Nulliparous females received relatively little grooming regardless of age or fertility. Thus, male chimpanzees apparently chose grooming partners based on both female's experience and fertility...

  15. Optimal harvesting of fish stocks under a time-varying discount rate.

    Science.gov (United States)

    Duncan, Stephen; Hepburn, Cameron; Papachristodoulou, Antonis

    2011-01-21

    Optimal control theory has been extensively used to determine the optimal harvesting policy for renewable resources such as fish stocks. In such optimisations, it is common to maximise the discounted utility of harvesting over time, employing a constant time discount rate. However, evidence from human and animal behaviour suggests that we have evolved to employ discount rates which fall over time, often referred to as "hyperbolic discounting". This increases the weight on benefits in the distant future, which may appear to provide greater protection of resources for future generations, but also creates challenges of time-inconsistent plans. This paper examines harvesting plans when the discount rate declines over time. With a declining discount rate, the planner reduces stock levels in the early stages (when the discount rate is high) and intends to compensate by allowing the stock level to recover later (when the discount rate will be lower). Such a plan may be feasible and optimal, provided that the planner remains committed throughout. However, in practice there is a danger that such plans will be re-optimized and adjusted in the future. It is shown that repeatedly restarting the optimization can drive the stock level down to the point where the optimal policy is to harvest the stock to extinction. In short, a key contribution of this paper is to identify the surprising severity of the consequences flowing from incorporating a rather trivial, and widely prevalent, "non-rational" aspect of human behaviour into renewable resource management models. These ideas are related to the collapse of the Peruvian anchovy fishery in the 1970's. Copyright © 2010 Elsevier Ltd. All rights reserved.

  16. Sensory and motor responses to rectal distention vary according to rate and pattern of balloon inflation.

    Science.gov (United States)

    Sun, W M; Read, N W; Prior, A; Daly, J A; Cheah, S K; Grundy, D

    1990-10-01

    Anorectal motor activity and rectal sensation were recorded in 12 normal male subjects during ramp distention of the rectum with water and air at randomized rates of 10, 20, 50, and 100 mL/min and during intermittent rapid distention with air. There were no significant differences between the results of ramp inflation with water or with air, and the repeated infusion of the same medium yielded reproducible results. Ramp distention induced sigmoid pressure-volume profiles. Different sensations occurred at specific points on the pressure-volume curve and were maintained until succeeded by the next sensation. Initial perception of the distention occurred during the initial steep pressure increase, the sensation of wind occurred during the plateau phase, and the desire to defecate occurred at the onset of the final rapid ascent. Rectal sensations were induced at lower volumes at low infusion rates when the slope of the pressure-volume relationship was shallower than at high infusion rates. This suggests that the receptor triggering rectal sensation is not a simple volume or pressure receptor, but is more likely to be a slowly adapting mechanoreceptor lying parallel to the circular muscle of the rectal wall. During rapid intermittent distention, the rectal volumes required to elicit rectal sensations were lower than during ramp distention, although the pressure-volume curve was steeper. Moreover, sensations often only lasted a short period of time but recurred on deflation. These data suggest activation of an additional population of rapidly adapting or high threshold mechanoreceptors. Anal relaxation was always evoked by intermittent rectal distention and was almost always associated with a rectal sensation and an increase in external anal sphincter activity. In contrast, anal relaxation could be absent or delayed during ramp inflation, especially at lower infusion rates, suggesting that internal sphincter can maintain continence for a long period of time while the

  17. Morphological Evolution of Gyroid-Forming Block Copolymer Thin Films with Varying Solvent Evaporation Rate.

    Science.gov (United States)

    Wu, Yi-Hsiu; Lo, Ting-Ya; She, Ming-Shiuan; Ho, Rong-Ming

    2015-08-05

    In this study, we aim to examine the morphological evolution of block copolymer (BCP) nanostructured thin films through solvent evaporation at different rates for solvent swollen polystyrene-block-poly(l-lactide) (PS-PLLA). Interesting phase transitions from disorder to perpendicular cylinder and then gyroid can be found while using a partially selective solvent for PS to swell PS-PLLA thin film followed by solvent evaporation. During the transitions, gyroid-forming BCP thin film with characteristic crystallographic planes of (111)G, (110)G, and (211)G parallel to air surface can be observed, and will gradually transform into coexisting (110)G and (211)G planes, and finally transforms to (211)G plane due to the preferential segregation of constituted block to the surface (i.e., the thermodynamic origin for self-assembly) that affects the relative amount of each component at the air surface. With the decrease on the evaporation rate, the disorder phase will transform to parallel cylinder and then directly to (211)G without transition to perpendicular cylinder phase. Most importantly, the morphological evolution of PS-PLLA thin films is strongly dependent upon the solvent removal rate only in the initial stage of the evaporation process due to the anisotropy of cylinder structure. Once the morphology is transformed back to the isotropic gyroid structure after long evaporation, the morphological evolution will only relate to the variation of the surface composition. Similar phase transitions at the substrate can also be obtained by controlling the ratio of PLLA-OH to PS-OH homopolymers to functionalize the substrate. As a result, the fabrication of well-defined nanostructured thin films with controlled orientation can be achieved by simple swelling and deswelling with controlled evaporation rate.

  18. Male chimpanzees' grooming rates vary by female age, parity, and fertility status.

    Science.gov (United States)

    Proctor, Darby P; Lambeth, Susan P; Schapiro, Steven J; Brosnan, Sarah F

    2011-10-01

    Copulation preferences in our closest living relative, the chimpanzee, suggest that males prefer older females who have had previous offspring. However, this finding is counter to some behavioral models, which predict that chimpanzee males, as promiscuous breeders with minimal costs to mating, should show little or no preference when choosing mating partners (e.g. should mate indiscriminately). To determine if the preferences indicated by copulations appear in other contexts as well as how they interact, we examined how male chimpanzees' grooming patterns varied amongst females. We found that males' preferences were based on interactions among females' fertility status, age, and parity. First, grooming increased with increasing female parity. We further found an effect of the estrous cycle on grooming; when females were at the lowest point of their cycle, males preferentially groomed parous females at peak reproductive age, but during maximal tumescence, males preferred the oldest multiparous females. Nulliparous females received relatively little grooming regardless of age or fertility. Thus, male chimpanzees apparently chose grooming partners based on both female's experience and fertility, possibly indicating a two-pronged social investment strategy. Male selectivity seems to have evolved to effectively distribute costly social resources in a pattern which may increase their overall reproductive success.

  19. Participants' ratings of male physicians who vary in race and communication style.

    Science.gov (United States)

    Aruguete, Mara S; Roberts, Carlos A

    2002-12-01

    Research has shown minorities receive lower quality health care than White persons even with socioeconomic conditions controlled. This difference may partially be related to racially biased attitudes and impaired communication in interracial relationships between physicians and patients. This study investigated the effect of physicians' race and nonverbal communication style on participants' evaluations. Patients at a local health clinic were participants (N = 116: 84% Black, 16% White). Each participant viewed one of four videotapes showing varied race of a physician (Black or White) and the physician's nonverbal behavior (expressing concern or distance), and then completed a questionnaire evaluating the depicted physician. Overall, participants did not give significantly different preferences for physicians of the same race. However, participants' evaluations were significantly associated with physicians' nonverbal style. Nonverbal concern was associated with highest satisfaction, trust, self-disclosure, recall of information, likelihood of recommending the physician, and intent to comply with the physician's recommendations. When male and female participants were compared, preference for a physician of the same race was found only among male participants who viewed verbally distant physicians. Results suggest that social skills are more important than race in shaping patients' perceptions of physicians.

  20. Effects of Biosolids at Varying Rates on Earthworms (Eisenia fetida and Springtails (Folsomia candida

    Directory of Open Access Journals (Sweden)

    N. Artuso

    2011-01-01

    Full Text Available Land spreading is a major option internationally for the disposal/use of treated sewage sludge (biosolids, but effects of this practice on soil organisms are largely unknown. This study investigated the effects of biosolids on two soil invertebrate species, earthworms (Eisenia fetida and Collembola (Folsomia candida, in laboratory tests. Five biosolids from different sewage works were assessed at rates equivalent to 0, 2, 5, 10, and 20 t ha−1. Biosolids applied at 2 and 5 t ha−1 did not cause mortality of adult earthworms but did at 10 and 20 t ha−1. At 5, 10 and 20 t ha−1, all biosolids had significantly fewer juvenile worms relative to controls. Increasing the rates from 2 to 10 t ha−1 did not impact on the number of adult Collembola, but at 20 t ha−1 there were significantly fewer adults. There were significantly fewer juvenile Collembola recorded for biosolids applied at the 2 t ha−1 when compared with controls, and also when biosolids were applied at 5, 10, and 20 t ha−1 relative to 2 t ha−1. Some significant difference between biosolids were observed, but generally, negative effects were not related to heavy metal concentrations in biosolids. It is recommended that possible detrimental mechanisms (e.g., ammonia production, lack of oxygen be investigated in future work. It is concluded that biosolids, applied at legal, low rates (about 2 t ha−1 are unlikely to be detrimental to earthworms or adult Collembola but can be detrimental to Collembola reproduction.

  1. Varying Rate of RNA Chain Elongation during rrn Transcription in Escherichia coli▿

    Science.gov (United States)

    Dennis, P. P.; Ehrenberg, M.; Fange, D.; Bremer, H.

    2009-01-01

    The value of the rRNA chain elongation rate in bacteria is an important physiological parameter, as it affects not only the rRNA promoter activity but also the free-RNA polymerase concentration and thereby the transcription of all genes. On average, rRNA chains elongate at a rate of 80 to 90 nucleotides (nt) per s, and the transcription of an entire rrn operon takes about 60 s (at 37°C). Here we have analyzed a reported distribution obtained from electron micrographs of RNA polymerase molecules along rrn operons in E. coli growing at 2.5 doublings per hour (S. Quan, N. Zhang, S. French, and C. L. Squires, J. Bacteriol. 187:1632-1638, 2005). The distribution exhibits two peaks of higher polymerase density centered within the 16S and 23S rRNA genes. An evaluation of this distribution indicates that RNA polymerase transcribes the 5′ leader region at speeds up to or greater than 250 nt/s. Once past the leader, transcription slows down to about 65 nt/s within the 16S gene, speeds up in the spacer region between the 16S and 23S genes, slows again to about 65 nt/s in the 23S region, and finally speeds up to a rate greater than 400 nt/s near the end of the operon. We suggest that the slowing of transcript elongation in the 16S and 23S sections is the result of transcriptional pauses, possibly caused by temporary interactions of the RNA polymerase with secondary structures in the nascent rRNA. PMID:19329648

  2. Production rates of bacterial tetraether lipids and fatty acids in peatland under varying oxygen concentrations

    Science.gov (United States)

    Huguet, Arnaud; Meador, Travis B.; Laggoun-Défarge, Fatima; Könneke, Martin; Wu, Weichao; Derenne, Sylvie; Hinrichs, Kai-Uwe

    2017-04-01

    Interpretations of the abundance and distribution of branched glycerol dialkyl glycerol tetraether (brGDGT) lipids have been increasingly applied to infer changes in paleoenvironment and to estimate terrigenous organic matter inputs into estuarine and marine sediments. However, only preliminary information is known regarding the ecology and physiology of the source organisms of these biomarkers. We assessed the production rates of brGDGTs under different redox conditions in peat, where these lipids are found in high concentrations, particularly at greater depths below the fluctuating water table. The incorporation of hydrogen relative to carbon into lipids observed in our dual stable isotope probing assay indicates that brGDGTs were produced by heterotrophic bacteria. Unexpectedly, incubations with stable isotope tracers of the surface horizon (5-20 cm) initiated under oxic conditions before turning suboxic and eventually anoxic exhibited up to one order of magnitude higher rates of brGDGT production (16-87 ng cm-3 y-1) relative to the deeper, anoxic zone (20-35 cm; ca. 7 ng cm-3 y-1), and anoxic incubations of the surface horizon (cell membrane in comparison to fatty acids, despite the typically high brGDGT concentrations observed in peat. Multivariate analysis identified two branched fatty acids that shared a similar production pattern as brGDGTs among the experimental treatments and may be associated with brGDGT biosynthesis.

  3. Analysis of Experiments Exhibiting Time-Varying Nuclear Decay Rates: Systematic Effects or New Physics?

    CERN Document Server

    Jenkins, Jere H; Sturrock, Peter A; Mundy, Daniel W

    2011-01-01

    Since the 1930s, and with very few exceptions, it has been assumed that the process of radioactive decay is a random process, unaffected by the environment in which the decaying nucleus resides. There have been instances within the past few decades, however, where changes in the chemical environment or physical environment brought about small changes in the decay rates. But even in light of these instances, decaying nuclei that were undisturbed or un-"pressured" were thought to behave in the expected random way, subject to the normal decay probabilities which are specific to each nuclide. Moreover, any "non-random" behavior was assumed automatically to be the fault of the detection systems, the environment surrounding the detectors, or changes in the background radiation to which the detector was exposed. Recently, however, evidence has emerged from a variety of sources, including measurements taken by independent groups at Brookhaven National Laboratory, Physikalisch-Technische Bundesanstalt, and Purdue Univ...

  4. System Availability in the Presence of Estimating Common-cause Time-varying Failure Rates

    Directory of Open Access Journals (Sweden)

    M. A. El-Damcese

    2005-01-01

    Full Text Available This study presents a method for calculating the availability of a system depicted by availability block diagram, with identically distributed components, in the presence of estimating common cause hazard, we use the Marshall and Olkin formulation of the multivariate exponential distribution. That is, the components are subject to failure by Poisson failure processes that govern simultaneous failure of a specific subset of the components. A model is proposed for the analysis of systems subject to common-cause failures that are not considered to have a constant rate but that are assumed to obey a uniqueness of maximum likelihood estimators of the 2-parameter Weibull distribution. The method for calculating the system availability requires that a procedure exists for determining the system availability from component availabilities, under the statistically independent component assumption. The study includes an example to illustrate the method.

  5. Recovery Rates of Human Fetal Skeletal Remains Using Varying Mesh Sizes.

    Science.gov (United States)

    Pokines, James T; De La Paz, Jade S

    2016-01-01

    Human fetal skeletal elements of different gestational ages were screened with multiple mesh sizes (6.4 mm [1/4 inch], 3.2 mm [1/8 inch], 2.0 mm, and 1.0 mm) to determine their recovery rates. All remains were previously macerated, and no significantly damaged elements were used. The 6.4 mm mesh allowed a large loss of elements (63.2% overall), including diagnostic elements, while no diagnostic elements were lost when the 1 mm mesh (0.2%) was used. When using the 3.2 mm mesh, 16.2% of the bones were lost, including some diagnostic elements (primarily tooth crowns), while 7.5% were lost using the 2.0 mm mesh. The authors recommend that the potential loss of information incurred when utilizing larger mesh sizes be taken into consideration when planning recovery methods where fetal remains may be encountered and that a minimum of 1.0 mm mesh be utilized in recovery contexts known to include fetal remains. © 2015 American Academy of Forensic Sciences.

  6. Why screening rates vary between Korea and Japan--differences between two national healthcare systems.

    Science.gov (United States)

    Goto, Rei; Hamashima, Chisato; Mun, Sunghyun; Lee, Won-Chul

    2015-01-01

    Both Japan and Korea provide population-based screening programs. However, screening rates are much higher in Korea than in Japan. To clarify the possible factors explaining the differences between these two countries, we analyzed the current status of the cancer screening and background healthcare systems. Population- based cancer screening in Korea is coordinated well with social health insurance under a unified insurer system. In Japan, there are over 3,000 insurers and coordinating a comprehensive strategy for cancer screening promotion has been very difficult. The public healthcare system also has influence over cancer screening. In Korea, public healthcare does not cover a wide range of services. Almost free cancer screening and subsidization for medical cost for cancers detected in population-screening provides high incentive to participation. In Japan, on the other hand, a larger coverage of medical services, low co-payment, and a lenient medical audit enables people to have cancer screening under public health insurance as well as the broad range of cancer screening. The implementation of evidence-based cancer screening programs may be largely dependent on the background healthcare system. It is important to understand the impacts of each healthcare system as a whole and to match the characteristics of a particular health system when designing an efficient cancer screening system.

  7. Effect of varied training techniques on field endotracheal intubation success rates.

    Science.gov (United States)

    Stewart, R D; Paris, P M; Pelton, G H; Garretson, D

    1984-11-01

    A pool of 146 mobile intensive care unit paramedics was divided into four equal groups and trained in the technique of direct laryngoscopic endotracheal intubation of cardiac arrest or deeply comatose patients. Group 1 was selected from supervisors and crew chiefs and trained as preceptors. The remaining paramedics were assigned to three other study groups. Groups 1 and 2 were trained with a didactic presentation followed by manikin practice, an animal laboratory exercise, and operating room experience. Group 3 had no OR experience; Group 4 had only didactic/manikin training. Intubations were observed by preceptors on scene. During the study period of 27 months, 689 of 763 patients (90.3%) were successfully intubated by 122 paramedics. While results suggest variation in skill levels according to training group (Group 1, 92.4%; Group 2, 87.6%, Group 3, 83.3%; Group 4, 76.9%), statistical analysis allowing for the variables of seniority and number of intubations performed by personnel failed to reveal differences in groups attributable to training programs. Complication rates were relatively low for all groups, the most common being prolonged intubation attempts. A significant improvement in the skill was seen as the study progressed when groups are pooled and compared. The findings suggest that endotracheal intubation of deeply comatose or cardiac arrest patients is a field procedure that can be performed safely and skillfully by well-monitored paramedical personnel. Operating room or animal laboratory experience may increase initial success levels, but these factors do not appear to greatly influence eventual performance or incidence of complications of the procedure.

  8. What causes EBRI retirement readiness ratings to vary: results from the 2014 Retirement Security Projection Model.

    Science.gov (United States)

    VanDerhei, Jack

    2014-02-01

    RETIREMENT INCOME ADEQUACY IMPROVED SLIGHTLY IN 2013: Due to the increase in financial market and housing values during 2013, the probability that Baby Boomers and Generation Xers would NOT run short of money in retirement increases between 0.5 and 1.6 percentage points, based on the Employee Benefit Research Institute (EBRI) Retirement Readiness Ratings (RRRs). ELIGIBILITY FOR PARTICIPATION IN AN EMPLOYER-SPONSORED DEFINED CONTRIBUTION PLAN REMAINS ONE OF THE MOST IMPORTANT FACTORS FOR RETIREMENT INCOME ADEQUACY: RRR values double for Gen Xers in the lowest-income quartile when comparing those with 20 or more years of future eligibility with those with no years of future eligibility, while those in the middle income quartiles experience increases in RRR values by 27.1-30.3 percentage points. FUTURE SOCIAL SECURITY BENEFITS MAKE A HUGE DIFFERENCE FOR THE RETIREMENT INCOME ADEQUACY OF SOME HOUSEHOLDS, ESPECIALLY GEN XERS IN THE LOWEST-INCOME QUARTILE: If Social Security benefits are subject to proportionate decreases beginning in 2033 (according to the values in Figure 8), the RRR values for those households will drop by more than 50 percent: from 20.9 percent to 10.3 percent. LONGEVITY RISK AND STOCHASTIC HEALTH CARE RISK ARE ASSOCIATED WITH HUGE VARIATIONS IN RETIREMENT INCOME ADEQUACY: For both of these factors, a comparison between the most "risky" quartile with the least risky quartile shows a spread of approximately 30 percentage points for the lowest income range, approximately 25 to 40 percentage points for the highest income range, and even larger spreads for those in the middle income ranges. A GREAT DEAL OF THE VARIABILITY IN RETIREMENT INCOME ADEQUACY COULD BE MITIGATED BY APPROPRIATE RISK-MANAGEMENT TECHNIQUES AT OR NEAR RETIREMENT AGE: For example, the annuitization of a portion of the defined contribution and IRA balances may substantially increase the probability of not running short of money in retirement. Moreover, a well-functioning market in long

  9. Lyapunov Functions for a Class of Discrete SIRS Epidemic Models with Nonlinear Incidence Rate and Varying Population Sizes

    Directory of Open Access Journals (Sweden)

    Ying Wang

    2014-01-01

    Full Text Available We investigate the dynamical behaviors of a class of discrete SIRS epidemic models with nonlinear incidence rate and varying population sizes. The model is required to possess different death rates for the susceptible, infectious, recovered, and constant recruitment into the susceptible class, infectious class, and recovered class, respectively. By using the inductive method, the positivity and boundedness of all solutions are obtained. Furthermore, by constructing new discrete type Lyapunov functions, the sufficient and necessary conditions on the global asymptotic stability of the disease-free equilibrium and endemic equilibrium are established.

  10. Convergence Rate for Discrete-Time Multiagent Systems With Time-Varying Delays and General Coupling Coefficients.

    Science.gov (United States)

    Chen, Yao; Ho, Daniel W C; Lü, Jinhu; Lin, Zongli

    2016-01-01

    Multiagent systems (MASs) are ubiquitous in our real world. There is an increasing attention focusing on the consensus (or synchronization) problem of MASs over the past decade. Although there are numerous results reported on the convergence of a discrete-time MAS based on the infinite products of matrices, few results are on the convergence rate. Because of the switching topology, the traditional eigenvalue analysis and the Lyapunov function methods are both invalid for the convergence rate analysis of an MAS with a switching topology. Therefore, the estimation of the convergence rate for a discrete-time MAS with time-varying delays remains a difficult problem. To overcome the essential difficulty of switching topology, this paper aims at developing a contractive-set approach to analyze the convergence rate of a discrete-time MAS in the presence of time-varying delays and generalized coupling coefficients. Using the proposed approach, we obtain an upper bound of the convergence rate under the condition of joint connectivity. In particular, the proposed method neither requires the nonnegative property of the coupling coefficients nor the basic assumption of a uniform lower bound for all positive coupling coefficients, which have been widely applied in the existing works on this topic. As an application of the main results, we will show that the classical Vicsek model with time delays can realize synchronization if the initial topology is connected.

  11. Micro-Viscometer for Measuring Shear-Varying Blood Viscosity over a Wide-Ranging Shear Rate.

    Science.gov (United States)

    Kim, Byung Jun; Lee, Seung Yeob; Jee, Solkeun; Atajanov, Arslan; Yang, Sung

    2017-06-20

    In this study, a micro-viscometer is developed for measuring shear-varying blood viscosity over a wide-ranging shear rate. The micro-viscometer consists of 10 microfluidic channel arrays, each of which has a different micro-channel width. The proposed design enables the retrieval of 10 different shear rates from a single flow rate, thereby enabling the measurement of shear-varying blood viscosity with a fixed flow rate condition. For this purpose, an optimal design that guarantees accurate viscosity measurement is selected from a parametric study. The functionality of the micro-viscometer is verified by both numerical and experimental studies. The proposed micro-viscometer shows 6.8% (numerical) and 5.3% (experimental) in relative error when compared to the result from a standard rotational viscometer. Moreover, a reliability test is performed by repeated measurement (N = 7), and the result shows 2.69 ± 2.19% for the mean relative error. Accurate viscosity measurements are performed on blood samples with variations in the hematocrit (35%, 45%, and 55%), which significantly influences blood viscosity. Since the blood viscosity correlated with various physical parameters of the blood, the micro-viscometer is anticipated to be a significant advancement for realization of blood on a chip.

  12. Effect of varying nitrogen flow rates on the optical properties of amorphous-SiCN thin films

    Science.gov (United States)

    Rahman, Mohd Azam Abdul; Tong, Goh Boon; Mahmood, Mohamad Rusop; Siong, Chiu Wee; Yian, Haw Choon; Rahman, Saadah Abdul

    2016-11-01

    Series of amorphous silicon carbon nitride (a-SiCN) films are synthesized using RF-PECVD technique on glass and silicon substrates from precursor gas of silane, methane and nitrogen. In this work, the change in nitrogen flow rate from 0 sccm to 50 sccm is a mean used to vary the elemental composition and bonding properties which lead to change in optical properties. The films thickness varies between 327 nm to 944 nm. The changes for the stated properties are discussed against the change in the stated nitrogen flow rate. The optical properties are investigated by means of UV-VIS spectroscopy in the wavelength range of 190 nm to 2500 nm. The transmittance of the films at ultra-violet wavelength is found to increases with increase in nitrogen flow rate. The index of refraction, n obtained for SiCN films from transmittance and reflectance measurements is lower compared to SiC films. The films optical band gap increases from 1.74 eV to 2.08 eV before it decreases to 1.89 eV as nitrogen flow rate increases from 0 to 50 sccm. The optical dispersion parameters were determined according to Wemple and Didomenico method.

  13. On the quantification of heart rate variability spectral parameters using time-frequency and time-varying methods.

    Science.gov (United States)

    Mainardi, Luca T

    2009-01-28

    In the last decades, one of the main challenges in the study of heart rate variability (HRV) signals has been the quantification of the low-frequency (LF) and high-frequency (HF) components of the HRV spectrum during non-stationary events. At this regard, different time-frequency and time-varying approaches have been proposed with the aim to track the modification of the HRV spectra during ischaemic attacks, provocative stress testing, sleep or daily-life activities. The quantitative evaluation of power (and frequencies) of the LF and HF components has been approached in various ways depending on the selected time-frequency method. This paper is an excursus through the most common time-frequency/time-varying representation of the HRV signal with a special emphasis on the algorithms employed for the reliable quantification of the LF and HF parameters and their tracking.

  14. Comparing N2O emissions at varying N rates from irrigated and rainfed corn in the US Midwest

    Science.gov (United States)

    Millar, N.; Kahmark, K.; Basso, B.; Robertson, G. P.

    2011-12-01

    Global N2O emissions from agriculture are estimated to be ~2.8 Pg CO2e yr-1 accounting for 60% of total anthropogenic emissions. N2O is the largest contributor to the GHG burden of cropping systems in the US, with annual estimated emissions of ~0.5 Tg primarily due to N fertilizer inputs and other soil management activities. Currently 23 million acres of corn, soybean and wheat are irrigated annually in the US with increased N2O emissions due to the practice likely under-reported in GHG inventories. Here we compare N2O emissions and yield from irrigated and rainfed corn at varying N rates between 0 and 246 kg N ha-1 from the Kellogg Biological Station in SW Michigan. Initial results show that N2O emissions increase with increasing N rate and are significantly higher from irrigated corn compared to rainfed corn at the same N rate. At increasing N rates daily emissions following an irrigation event were between 2.4 - 77.5 g N2O-N ha-1 from irrigated corn and 1.6 - 13.0 g N2O-N ha-1 from rainfed corn. Emissions data from automated and static chambers will be presented and trade-offs between N2O emissions, N fertilizer rate, crop yield and irrigation practice will be evaluated from an environmental and economic standpoint.

  15. A DECODER NMR study of backbone orientation in Nephila clavipes dragline silk under varying strain and draw rate.

    Science.gov (United States)

    Eles, Philip T; Michal, Carl A

    2004-01-01

    Using DECODER (direction exchange with correlation for orientation distribution evaluation and reconstruction) NMR, we probe the orientations of carbonyl carbons in [1-(13)C]glycine-labeled dragline silk under conditions of varying strain and fiber draw rate. A model-specific reconstruction of the molecular orientation distribution incorporating beta sheets and polyglycine II helices indicates that the structures' alignment along the fiber can be described by a pair of Gaussian distributions with full width at half-maxima of 20 and 68 degrees and approximately 45 and approximately 55% relative contributions to the signal intensity. The alignment along the fiber was found to change appreciably when the drawing tension on the fiber was relaxed in a sample drawn at 4 cm/s while little change was observed in a sample drawn at 2 cm/s. The degree of alignment along the fiber was found to increase with fiber draw rate.

  16. Time-varying correlations between delta EEG power and heart rate variability in midlife women: the SWAN Sleep Study.

    Science.gov (United States)

    Rothenberger, Scott D; Krafty, Robert T; Taylor, Briana J; Cribbet, Matthew R; Thayer, Julian F; Buysse, Daniel J; Kravitz, Howard M; Buysse, Evan D; Hall, Martica H

    2015-04-01

    No studies have evaluated the dynamic, time-varying relationship between delta electroencephalographic (EEG) sleep and high frequency heart rate variability (HF-HRV) in women. Delta EEG and HF-HRV were measured during sleep in 197 midlife women (M(age)  = 52.1, SD = 2.2). Delta EEG-HF-HRV correlations in nonrapid eye movement (NREM) sleep were modeled as whole-night averages and as continuous functions of time. The whole-night delta EEG-HF-HRV correlation was positive. The strongest correlations were observed during the first NREM sleep period preceding and following peak delta power. Time-varying correlations between delta EEG-HF-HRV were stronger in participants with sleep-disordered breathing and self-reported insomnia compared to healthy controls. The dynamic interplay between sleep and autonomic activity can be modeled across the night to examine within- and between-participant differences including individuals with and without sleep disorders.

  17. Correction of dead-time and pile-up in a detector array for constant and rapidly varying counting rates

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero, C. [Centro de Investigaciones Medioambientales, Energéticas y Tecnológicas (CIEMAT), Madrid (Spain); Departamento de Física Atómica, Molecular y Nuclear, Universidad de Sevilla (Spain); Cano-Ott, D.; Mendoza, E. [Centro de Investigaciones Medioambientales, Energéticas y Tecnológicas (CIEMAT), Madrid (Spain); Wright, T. [University of Manchester, Manchester (United Kingdom)

    2015-03-21

    The effect of dead-time and pile-up in counting experiments may become a significant source of uncertainty if not properly taken into account. Although analytical solutions to this problem have been proposed for simple set-ups with one or two detectors, these are limited when it comes to arrays where time correlation between the detector modules is used, and also in situations of variable counting rates. In this paper we describe the dead-time and pile-up corrections applied to the n-TOF Total Absorption Calorimeter (TAC), a 4π γ-ray detector made of 40 BaF{sub 2} modules operating at the CERN n-TOF facility. Our method is based on the simulation of the complete signal detection and event reconstruction processes and can be applied as well in the case of rapidly varying counting rates. The method is discussed in detail and then we present its successful application to the particular case of the measurement of {sup 238}U(n, γ) reactions with the TAC detector.

  18. Transport critical current of MgB2 wires: pulsed current of varying rate compared to direct current method

    Science.gov (United States)

    See, K. W.; Xu, X.; Horvat, J.; Cook, C. D.; Dou, S. X.

    2011-10-01

    The measurement of transport critical current (Ic) for MgB2 wires and tapes has been investigated with two different techniques, the conventional four-probe arrangement with direct current (DC) power source, and a tailored triangle pulse at different rates of current change. The DC method has been widely used and practiced by various groups, but suffers from inevitable heating effects when high currents are used at low magnetic fields. The pulsed current method has no heating effects, but the critical current can depend on the rate of the current change (dI/dt) in the pulse. Our pulsed current measurements with varying dI/dt show that the same values of Ic are obtained as with the DC method, but without the artifacts of heating. Our method is particularly useful at low field regions which are often inaccessible by DC methods. We also performed a finite element method (FEM) analysis to obtain the time dependent heat distribution in MgB2 due to the electric potential produced at the current contacts to the superconducting sample and its gradient around the contacts. This gradient is defined as the current transfer length (CTL) of the samples and leads to Joule heating of the wire near the contacts. The FEM results provide further evidence of the limitation of the DC method in obtaining high transport critical current.

  19. Time-varying surrogate data to assess nonlinearity in nonstationary time series: application to heart rate variability.

    Science.gov (United States)

    Faes, Luca; Zhao, He; Chon, Ki H; Nollo, Giandomenico

    2009-03-01

    We propose a method to extend to time-varying (TV) systems the procedure for generating typical surrogate time series, in order to test the presence of nonlinear dynamics in potentially nonstationary signals. The method is based on fitting a TV autoregressive (AR) model to the original series and then regressing the model coefficients with random replacements of the model residuals to generate TV AR surrogate series. The proposed surrogate series were used in combination with a TV sample entropy (SE) discriminating statistic to assess nonlinearity in both simulated and experimental time series, in comparison with traditional time-invariant (TIV) surrogates combined with the TIV SE discriminating statistic. Analysis of simulated time series showed that using TIV surrogates, linear nonstationary time series may be erroneously regarded as nonlinear and weak TV nonlinearities may remain unrevealed, while the use of TV AR surrogates markedly increases the probability of a correct interpretation. Application to short (500 beats) heart rate variability (HRV) time series recorded at rest (R), after head-up tilt (T), and during paced breathing (PB) showed: 1) modifications of the SE statistic that were well interpretable with the known cardiovascular physiology; 2) significant contribution of nonlinear dynamics to HRV in all conditions, with significant increase during PB at 0.2 Hz respiration rate; and 3) a disagreement between TV AR surrogates and TIV surrogates in about a quarter of the series, suggesting that nonstationarity may affect HRV recordings and bias the outcome of the traditional surrogate-based nonlinearity test.

  20. Sensitivity of CO2 storage performance to varying rates and dynamic injectivity in the Bunter Sandstone, UK

    Science.gov (United States)

    Kolster, C.; Mac Dowell, N.; Krevor, S. C.; Agada, S.

    2016-12-01

    Carbon capture and storage (CCS) is needed for meeting legally binding greenhouse gas emissions targets in the UK (ECCC 2016). Energy systems models have been key to identifying the importance of CCS but they tend to impose few constraints on the availability and use of geologic CO2 storage reservoirs. Our aim is to develop simple models that use dynamic representations of limits on CO2 storage resources. This will allow for a first order representation of the storage reservoir for use in systems models with CCS. We use the ECLIPSE reservoir simulator and a model of the Southern North Sea Bunter Sandstone saline aquifer. We analyse reservoir performance sensitivities to scenarios of varying CO2 injection demand for a future UK low carbon energy market. With 12 injection sites, we compare the impact of injecting at a constant 2MtCO2/year per site and varying this rate by a factor of 1.8 and 0.2 cyclically every 5 and 2.5 years over 50 years of injection. The results show a maximum difference in average reservoir pressure of 3% amongst each case and a similar variation in plume migration extent. This suggests that simplified models can maintain accuracy by using average rates of injection over similar time periods. Meanwhile, by initiating injection at rates limited by pressurization at the wellhead we find that injectivity steadily increases. As a result, dynamic capacity increases. We find that instead of injecting into sites on a need basis, we can strategically inject the CO2 into 6 of the deepest sites increasing injectivity for the first 15 years by 13%. Our results show injectivity as highly dependent on reservoir heterogeneity near the injection site. Injecting 1MTCO2/year into a shallow, low permeability and porosity site instead of into a deep injection site with high permeability and porosity reduces injectivity in the first 5 years by 52%. ECCC. 2016. Future of Carbon Capture and Storage in the UK. UK Parliament House of Commons, Energy and Climate Change

  1. Study on unplanned re-operation after radical gastrectomy for gastric cancer: Seven years' experience%胃癌根治术后非计划再手术35例

    Institute of Scientific and Technical Information of China (English)

    黄嫣妮; 钱雷敏; 黄建明; 戈军刚; 高林; 刘惠钧

    2013-01-01

    Objective To investigate the causes of unplanned re-operation following radical surgery for gastric cancer and to summarize clinical experience.Methods The clinical data of gastric cancer patients who underwent radical gastrectomy from Jan.2006 to Dec.2012 were retrospectively analyzed in the study,especially focusing on the preoperative,intraoperative and postoperative situations of unplanned re-operation cases at the same hospitalization.Results During seven years,radical gastrectomy for gastric cancer was implemented in 1707 cases,35 of which had unplanned re-operations.The rate of such re-operation was 2.05 %,following the mortality rate of 8.57%.Besides age,basic chronic illness and TNM stage,the primary operation way,which caused the higher incidence of unplanned re-operation,was radical total gastrectomy.Some complications after radical gastrectomy required unplanned re-operations,of which the most common was wound disruption and others,in turn,were pleural effusions/ascites,post-traumatic focal pancreatitis (PTFP),intestinal obstruction,intraperitoneal hemorrhage,while the most serious consequence was anastomotic leakage or stump fistula and partly led to death.Conclusion Unplanned re-operation after radical gastrectomy for gastric cancer can increase residential time,total treatment cost and the mortality rate.Comprehensive preoperative analysis,correct intraoperative and postoperative management,as well as timely treatment of complications are important measures to reduce the incidence of those unplanned re-operations.%目的 探讨胃癌根治术后非计划再手术的原因及总结临床治疗体会.方法 回顾性分析2006年1月—2012年12月间行胃癌根治术患者的临床资料,并重点分析同一住院期间非计划再手术病例的术前、手术及术后情况.结果 7年间共实施胃癌根治术1 707例,发生非计划再手术35例,再手术率2.05%,再手术死亡率8.57%.发生率较高者的初次手术方式为根治

  2. How Do Algebra I Course Repetition Rates Vary among English Learner Students by Length of Time to Reclassification as English Proficient? REL 2017-222

    Science.gov (United States)

    Jaquet, Karina; Fong, Anthony B.

    2017-01-01

    Research has found high repetition rates for students in Algebra I, with one study finding a repetition rate of 44 percent for students in a large urban high school district. Less is known about how math performance and Algebra I course repetition rates vary among students with different levels of English proficiency. This report examines Algebra…

  3. The Effect of Bicycle Ergometer Exercise at Varying Intensities on the Heart Rate, EMG and Mood State Responses to a Mental Arithmetic Stressor.

    Science.gov (United States)

    McGowan, Colleen R.; And Others

    1985-01-01

    This study examined the effect of bicycle ergometer exercise at varying metabolic intensities upon the heart rate, electromyographic (EMG), and mood state responses to a timed mental arithmetric stressor of 12 adult males. Exercise influenced heart rate and EMG but not physiological and psychological responses to the arithmetic stressor.…

  4. The effects of varying injection rates in Osage County, Oklahoma, on the 2016 Mw5.8 Pawnee earthquake

    Science.gov (United States)

    Barbour, Andrew J.; Norbeck, Jack H.; Rubinstein, Justin L.

    2017-01-01

    The 2016 Mw 5.8 Pawnee earthquake occurred in a region with active wastewater injection into a basal formation group. Prior to the earthquake, fluid injection rates at most wells were relatively steady, but newly collected data show significant increases in injection rate in the years leading up to earthquake. For the same time period, the total volumes of injected wastewater were roughly equivalent between variable‐rate and constant‐rate wells. To understand the possible influence of these changes in injection, we simulate the variable‐rate injection history and its constant‐rate equivalent in a layered poroelastic half‐space to explore the interplay between pore‐pressure effects and poroelastic effects on the fault leading up to the mainshock. In both cases, poroelastic stresses contribute a significant proportion of Coulomb failure stresses on the fault compared to pore‐pressure increases alone, but the resulting changes in seismicity rate, calculated using a rate‐and‐state frictional model, are many times larger when poroelastic effects are included, owing to enhanced stressing rates. In particular, the variable‐rate simulation predicts more than an order of magnitude increase in seismicity rate above background rates compared to the constant‐rate simulation with equivalent volume. The observed cumulative density of earthquakes prior to the mainshock within 10 km of the injection source exhibits remarkable agreement with seismicity predicted by the variable‐rate injection case.

  5. The genome as a life-history character: why rate of molecular evolution varies between mammal species

    Science.gov (United States)

    Bromham, Lindell

    2011-01-01

    DNA sequences evolve at different rates in different species. This rate variation has been most closely examined in mammals, revealing a large number of characteristics that can shape the rate of molecular evolution. Many of these traits are part of the mammalian life-history continuum: species with small body size, rapid generation turnover, high fecundity and short lifespans tend to have faster rates of molecular evolution. In addition, rate of molecular evolution in mammals might be influenced by behaviour (such as mating system), ecological factors (such as range restriction) and evolutionary history (such as diversification rate). I discuss the evidence for these patterns of rate variation, and the possible explanations of these correlations. I also consider the impact of these systematic patterns of rate variation on the reliability of the molecular date estimates that have been used to suggest a Cretaceous radiation of modern mammals, before the final extinction of the dinosaurs. PMID:21807731

  6. Study of mechanical properties, microstructures and corrosion behavior of al 7075 t651 alloy with varying strain rate

    Science.gov (United States)

    Mukherjee, A.; Ghosh, M.; Mondal, K.; Venkitanarayanan, P.; Moon, A. P.; Varshney, A.

    2015-02-01

    Compression test of Al 7075 T651 was carried out at high strain rates (1138 - 2534 s-1) using Split Hopkinson Pressure Bar and at slow strain rate (10-4s-1) in 100KN Universal Testing machine to understand the improvement in mechanical properties and associated changes in microstructures. Cylindrical specimens of 6 mm height and 6 mm diameter were compressed dynamically. The influence of strain rates on mechanical properties, microstructure evolution and corrosion behavior after immersion test in 3.5% NaCl solution was also investigated. Strain rate, withdrawal stress and yield stress were observed to increase with impact velocity in high strain rate tests, while in slow strain rate tests, n value was observed to increase with increasing total strain. Microstructural observations revealed that after high strain rate test, grains of Al matrix were elongated. It was observed that corrosion resistance decreased with increase in impact velocity.

  7. Applications of the Time-Varying Multi-Hazard Index to Armed Conflicts and GDP Growth Rate

    Science.gov (United States)

    Isanuk, M.; Skorik, A.; Lerner-Lam, A.

    2004-12-01

    The time-varying Multi-Hazard Index has many potential applications for comparisons against quantitative measures of sustainable development. We have compared the time-varying severity of multiple natural hazards against time-varying socio-economic data for selected countries. Our analysis compares Gross Domestic Product (GDP) growth and armed conflict occurrence against multiple hazard severity as measured by an empirical time-varying multiple hazard index. The purpose of these analyses is to establish and characterize correlations between the Multi-Hazard Index and trends in GDP and conflicts over the past 25 years. To analyze the relationship between natural hazards and armed conflicts, the Multi-Hazard Index was correlated against the number of conflicts at each intensity level for individual countries. A preliminary analysis was performed studying the apparent relationship as well as the possible existence of time lags. In a similar although more quantitative analysis, the GDP data was correlated against the Multi-Hazard Index for a particular country at different time lags. Analysis involving the conflict datasets yielded varying results from country to country. Colombia shows the strongest correlation, with all positive values of the Multi-Hazard Index followed by an escalation in conflict intensity. The results for other countries are more difficult to interpret as certain years show increases in the number of conflicts at one intensity level and a decrease for other intensity levels. Some issues that need to be addressed include the coding of the intensity for the conflict data, the dating for both conflicts and hazards, and the use of national boundaries as geographic extents. The degree of correlation between GDP growth and the Multi-Hazard Index varies from country to country as well. Our calculations for Honduras show an extremely high correlation, for example, implying a strong economic sensitivity to natural hazards, whereas for China no significant

  8. Generalized peritonitis requiring re-operation after leakage of omental patch repair of perforated peptic ulcer

    Directory of Open Access Journals (Sweden)

    Hemmat Maghsoudi

    2011-01-01

    Full Text Available Background/Aim: Peptic ulcer perforations are a common emergency, but available literature is silent on the exact definition, incidence, management, and complications of peritonitis due to omental patch leakage. Patients and Methods: Retrospective data were collected on 422 patients who underwent omental patch repair of perforated peptic ulcer between March 20, 1999 and March 20, 2006. The definitive diagnosis of perforated peptic ulcer and omental patch leakage was obtained at surgery. Results: Seventeen (4% patients experienced generalized peritonitis due to omental patch leakage. Mean age was 60.6 years. Mortality rate was 29.4%, and the mean hospital stay was 23.6 days. Delay in surgical approach, shock on admission, and age were all significantly associated with increased mortality. Conclusions: Peritonitis due to omental patch leakage can result in significant morbidity and mortality. The most common causes of omental patch leakage and operative procedures were unknown and reinsertion of omentum, respectively. Factors such as shock on admission or delayed surgery, have significantly contributed to fatal outcomes and need careful attention.

  9. Microsatellite frequencies vary with body mass and body temperature in mammals, suggesting correlated variation in mutation rate

    Directory of Open Access Journals (Sweden)

    William Amos

    2014-11-01

    Full Text Available Substitution rate is often found to correlate with life history traits such as body mass, a predictor of population size and longevity, and body temperature. The underlying mechanism is unclear but most models invoke either natural selection or factors such as generation length that change the number of mutation opportunities per unit time. Here we use published genome sequences from 69 mammals to ask whether life history traits impact another form of genetic mutation, the high rates of predominantly neutral slippage in microsatellites. We find that the length-frequency distributions of three common dinucleotide motifs differ greatly between even closely related species. These frequency differences correlate with body mass and body temperature and can be used to predict the phenotype of an unknown species. Importantly, different length microsatellites show complicated patterns of excess and deficit that cannot be explained by a simple model where species with short generation lengths have experienced more mutations. Instead, the patterns probably require changes in mutation rate that impact alleles of different length to different extents. Body temperature plausibly influences mutation rate by modulating the propensity for slippage. Existing hypotheses struggle to account for a link between body mass and mutation rate. However, body mass correlates inversely with population size, which in turn predicts heterozygosity. We suggest that heterozygote instability, HI, the idea that heterozygous sites show increased mutability, could provide a plausible link between body mass and mutation rate.

  10. A Simulation of the Effects of Varying Repetition Rate and Pulse Width of Nanosecond Discharges on Premixed Lean Methane-Air Combustion

    Directory of Open Access Journals (Sweden)

    Moon Soo Bak

    2012-01-01

    Full Text Available Two-dimensional kinetic simulation has been carried out to investigate the effects of repetition rate and pulse width of nanosecond repetitively pulsed discharges on stabilizing premixed lean methane-air combustion. The repetition rate and pulse width are varied from 10 kHz to 50 kHz and from 9 ns to 2 ns while the total power is kept constant. The lower repetition rates provide larger amounts of radicals such as O, H, and OH. However, the effect on stabilization is found to be the same for all of the tested repetition rates. The shorter pulse width is found to favor the production of species in higher electronic states, but the varying effects on stabilization are also found to be small. Our results indicate that the total deposited power is the critical element that determines the extent of stabilization over this range of discharge properties studied.

  11. Variation in the Slope Coefficient of the Fama Regression for Testing Uncovered Interest Rate Parity: Evidence from Fixed and Time-varying Coefficient Approaches

    OpenAIRE

    Koning, Camiel de; Straetmans, S.

    1997-01-01

    textabstractWe investigate the potential presence of time variation in the coefficients of the ''Fama regression'' for Uncovered Interest Rate Parity. We implement coefficient constancy tests, rolling regression techniques, and stochastic coefficient models based on state space modelling. Among six major US bilateral exchange rates we find significant evidence for stochastic time variation. Using the statistical equivalence between stochastically varying coefficients and conditional heterosce...

  12. Recovery from exercise at varying work loads - Time course of responses of heart rate and systolic intervals

    Science.gov (United States)

    Nandi, P. S.; Spodick, D. H.

    1977-01-01

    The time course of the recovery period was characterized by noninvasive measurements after 4 minute bicycle exercise at 3 separate work loads in volunteers with normal peak responses. Most responses started immediately to return toward resting control values. Left ventricular ejection time and stroke volume change are discussed. Changes in pre-ejection period were determined by changes in isovolume contraction time, and factors affecting the degree and rate of return are considered. The rates of change in the ejection time index and in the ratio pre-ejection period/left ventricular ejection time were virtually independent of load throughout most of recovery.

  13. Recovery from exercise at varying work loads - Time course of responses of heart rate and systolic intervals

    Science.gov (United States)

    Nandi, P. S.; Spodick, D. H.

    1977-01-01

    The time course of the recovery period was characterized by noninvasive measurements after 4 minute bicycle exercise at 3 separate work loads in volunteers with normal peak responses. Most responses started immediately to return toward resting control values. Left ventricular ejection time and stroke volume change are discussed. Changes in pre-ejection period were determined by changes in isovolume contraction time, and factors affecting the degree and rate of return are considered. The rates of change in the ejection time index and in the ratio pre-ejection period/left ventricular ejection time were virtually independent of load throughout most of recovery.

  14. Rates of energy processing by blowflies: the uses for a joule vary with food quality and quantity.

    Science.gov (United States)

    Hainsworth, F R; Fisher, G; Precup, E

    1990-05-01

    Data on the variation of crop volumes with time for blowflies (Phormia regina Meigen) fed various volumes and concentrations of fructose or sucrose (from Gelperin, 1966, and Edgecomb et al. 1987) were used to characterize energy processing rates to test the assumption of food energy addivity of optimal foraging theories. Six regression models (linear, square root, cube root, hyperbolic, inverse cube root and exponential) were compared for data from Edgecomb et al. (1987) with measurements of crop volumes from 10 min to 5 h after blowflies were fed 9.7 or 14.5 microliters of 0.25 moll-1 sucrose. Only the hyperbolic regression could be discriminated as statistically different, and the linear model was selected as most parsimonious for examining rates of energy processing. About the same volume bypassed the crop for flies fed 9.7 or 14.5 microliters. Volume rates of crop emptying (from Gelperin, 1966) did not change at intermediate concentrations but decreased from lowest and to highest concentrations. Energy processing patterns indicate that long-term storage rates increase with meal size and at intermediate concentrations and decrease (3.0 moll-1 fructose) or remain constant (2.0 moll-1 sucrose) at high concentrations, so the uses for a unit of energy are not additive across concentrations and meal sizes. Animals that process energy in this way should attempt to maximize meal size and include high-energy foods in their diet out of proportion to the amount of energy gained for the time spent foraging.

  15. Carnitine palmitoyl transferase activity and whole muscle oxidation rates vary with fatty acid substrate in avian flight muscles.

    Science.gov (United States)

    Price, Edwin R; Staples, James F; Milligan, C Louise; Guglielmo, Christopher G

    2011-05-01

    Birds primarily fuel migratory flights with fat, and the composition of that fat has the potential to affect overall lipid oxidation rates. We measured the whole muscle lipid oxidation rates in extensor digitorum communis muscles from white-throated sparrows (Zonotrichia albicollis Gmelin) incubated for 20 min at 20°C with radiolabeled stearate (18:0), oleate (18:1ω9), or linoleate (18:2ω6). Lipid oxidation rates were ~40% higher with linoleate than oleate (oleate: 36 ± 8.54 μmol CO(2) g(-1) h(-1)), and ~75% lower with stearate compared with oleate, indicating that maximal lipid oxidation rates can indeed be affected by the type of fatty acid supplied to the muscle. Additionally, we investigated the activity of the mitochondrial fatty acid transport-associated enzyme carnitine palmitoyl transferase (CPT) in pectoralis muscles of 5 bird species (Zonotrichia albicollis, Philomachus pugnax, Sturnus vulgaris, Taeniopygia guttata, Passer domesticus). Activity was measured in homogenized samples using various fatty acyl-CoA substrates (16:0, 16:1, 18:0, 18:1ω9, 18:2ω6, 18:3ω3, 18:3ω6, 20:0, 20:4ω6, 22:6ω3) in a spectrophotometric assay. CPT activity increased with the degree of unsaturation and decreased with chain length. CPT activity did not differ between ω3 and ω6 isomers of 18:3, nor was the pattern of CPT substrate preference different between captive white-throated sparrows in a migratory (i.e., displaying Zugunruhe) or non-migratory state. These findings can explain previously observed differences in peak performance induced by dietary fat composition and suggest that lipid supply is limiting to maximal exercise performance in birds.

  16. LOSS Revisited. II. The Relative Rates of Different Types of Supernovae Vary between Low- and High-mass Galaxies

    Science.gov (United States)

    Graur, Or; Bianco, Federica B.; Modjaz, Maryam; Shivvers, Isaac; Filippenko, Alexei V.; Li, Weidong; Smith, Nathan

    2017-03-01

    In Paper I of this series, we showed that the ratio between stripped-envelope (SE) supernova (SN) and Type II SN rates reveals a significant SE SN deficiency in galaxies with stellar masses ≲ {10}10 {M}ȯ . Here, we test this result by splitting the volume-limited subsample of the Lick Observatory Supernova Search (LOSS) SN sample into low- and high-mass galaxies and comparing the relative rates of various SN types found in them. The LOSS volume-limited sample contains 180 SNe and SN impostors and is complete for SNe Ia out to 80 Mpc and core-collapse SNe out to 60 Mpc. All of these transients were recently reclassified by us in Shivvers et al. We find that the relative rates of some types of SNe differ between low- and high-mass galaxies: SNe Ib and Ic are underrepresented by a factor of ∼3 in low-mass galaxies. These galaxies also contain the only examples of SN 1987A-like SNe in the sample and host about nine times as many SN impostors. Normal SNe Ia seem to be ∼30% more common in low-mass galaxies, making these galaxies better sources for homogeneous SN Ia cosmology samples. The relative rates of SNe IIb are consistent in both low- and high-mass galaxies. The same is true for broad-line SNe Ic, although our sample includes only two such objects. The results presented here are in tension with a similar analysis from the Palomar Transient Factory, especially as regards SNe IIb.

  17. LOSS Revisited - II: The relative rates of different types of supernovae vary between low- and high-mass galaxies

    CERN Document Server

    Graur, Or; Modjaz, Maryam; Shivvers, Isaac; Filippenko, Alexei V; Li, Weidong; Smith, Nathan

    2016-01-01

    In Paper I of this series, we showed that the ratio between stripped-envelope supernova (SE SN) and Type II SN rates reveals a significant SE SN deficiency in galaxies with stellar masses $\\lesssim 10^{10}~{\\rm M}_\\odot$. Here, we test this result by splitting the volume-limited subsample of the Lick Observatory Supernova Search (LOSS) SN sample into low- and high-mass galaxies and comparing the relative rates of various SN types found in them. The LOSS volume-limited sample contains 180 SNe and SN impostors and is complete for SNe Ia out to 80 Mpc and core-collapse SNe out to 60 Mpc. All of these transients were recently reclassified by us in Shivvers et al. (in prep.) We find that the relative rates of some types of SNe differ between low- and high-mass galaxies: SNe Ib and Ic are underrepresented by a factor of ~3 in low-mass galaxies. These galaxies also contain the only examples of SN 1987A-like SNe in the sample and host ~9 times as many SN impostors. Normal SNe Ia are ~30% more common in low-mass galax...

  18. Decoupling control in velocity-varying four-wheel steering vehicles with H∞ performance by longitudinal velocity and yaw rate feedback

    Science.gov (United States)

    Li, Mingxing; Jia, Yingmin

    2014-12-01

    In this paper, decoupling control with H∞ performance for four-wheel steering (4WS) vehicles under varying longitudinal velocity is studied. A novel control scheme for a nonlinear model of three states, respectively, the longitudinal and lateral velocities, and yaw rate, is proposed to address this issue. The scheme is composed of two varying-parameter controllers designing problems for both longitudinal and lateral systems with coupling performance. Varying parameters of both these controllers depend only on longitudinal velocity. Controlled by these controllers, the longitudinal system is decoupled with lateral velocity and yaw rate, and the lateral system is input-output decoupling with H∞ performance. In addition, feedback signals are the longitudinal velocity and yaw rate, hence observations or measurements of lateral velocity are not necessary. Simulations show that vehicles controlled by our scheme are input-output diagonal decoupling and execute very well while longitudinal velocity varies in a large range, coupling appears between longitudinal and lateral systems, and external disturbances do exist. In summary, this control scheme can improve handling characteristics, safety and comfort proved from theory to practice in this paper.

  19. Affective resonance in response to others' emotional faces varies with affective ratings and psychopathic traits in amygdala and anterior insula.

    Science.gov (United States)

    Seara-Cardoso, Ana; Sebastian, Catherine L; Viding, Essi; Roiser, Jonathan P

    2016-01-01

    Despite extensive research on the neural basis of empathic responses for pain and disgust, there is limited data about the brain regions that underpin affective response to other people's emotional facial expressions. Here, we addressed this question using event-related functional magnetic resonance imaging to assess neural responses to emotional faces, combined with online ratings of subjective state. When instructed to rate their own affective response to others' faces, participants recruited anterior insula, dorsal anterior cingulate, inferior frontal gyrus, and amygdala, regions consistently implicated in studies investigating empathy for disgust and pain, as well as emotional saliency. Importantly, responses in anterior insula and amygdala were modulated by trial-by-trial variations in subjective affective responses to the emotional facial stimuli. Furthermore, overall task-elicited activations in these regions were negatively associated with psychopathic personality traits, which are characterized by low affective empathy. Our findings suggest that anterior insula and amygdala play important roles in the generation of affective internal states in response to others' emotional cues and that attenuated function in these regions may underlie reduced empathy in individuals with high levels of psychopathic traits.

  20. An analysis of the mechanism of a reactivated basaltic landslide site under varying rate of displacement in Mauritius, Offshore Africa

    Science.gov (United States)

    Dabycharun, Bhoopendra; Kuwano, Takeshi; Ichikawa, Kensuke; Fukuoka, Hiroshi

    2017-04-01

    dry condition, the residual friction angle (φ) and the cohesion (c) were found to be 18.8o and 8.0 kPa respectively whereas, under the fully saturated condition, the residual friction angle (φ) and the cohesion (c) were found to be 12.0o and 5.0 kPa respectively. Ring shear test was conducted under increasing shear speed from 0.01mm/min to 0.3 mm/min to determine the mechanism of the accelerating movement of the soil. The rate effect test concluded that the soils showed positive rate effect as the stress ratio under faster shear rate was higher than the one under slower rate. Thus, under a high degree of saturation, the landslide will continue to accelerate with the generation of excess pore water pressure while shear resistance will be recovered at high speeds. Intermittent movement will be repeated with this type of mechanism.

  1. Observer-based robust finite time H∞ sliding mode control for Markovian switching systems with mode-dependent time-varying delay and incomplete transition rate.

    Science.gov (United States)

    Gao, Lijun; Jiang, Xiaoxiao; Wang, Dandan

    2016-03-01

    This paper investigates the problem of robust finite time H∞ sliding mode control for a class of Markovian switching systems. The system is subjected to the mode-dependent time-varying delay, partly unknown transition rate and unmeasurable state. The main difficulty is that, a sliding mode surface cannot be designed based on the unknown transition rate and unmeasurable state directly. To overcome this obstacle, the set of modes is firstly divided into two subsets standing for known transition rate subset and unknown one, based on which a state observer is established. A component robust finite-time sliding mode controller is also designed to cope with the effect of partially unknown transition rate. It is illustrated that the reachability, finite-time stability, finite-time boundedness, finite-time H∞ state feedback stabilization of sliding mode dynamics can be ensured despite the unknown transition rate. Finally, the simulation results verify the effectiveness of robust finite time control problem.

  2. The wind speeds, dust content, and mass-loss rates of evolved AGB and RSG stars at varying metallicity

    Science.gov (United States)

    Goldman, Steven R.; van Loon, Jacco Th.; Zijlstra, Albert A.; Green, James A.; Wood, Peter R.; Nanni, Ambra; Imai, Hiroshi; Whitelock, Patricia A.; Matsuura, Mikako; Groenewegen, Martin A. T.; Gómez, José F.

    2017-02-01

    We present the results of our survey of 1612-MHz circumstellar OH maser emission from asymptotic giant branch (AGB) stars and red supergiants (RSGs) in the Large Magellanic Cloud (LMC). We have discovered four new circumstellar maser sources in the LMC, and increased the number of reliable wind speeds from infrared (IR) stars in the LMC from 5 to 13. Using our new wind speeds, as well as those from Galactic sources, we have derived an updated relation for dust-driven winds: vexp ∝ ZL0.4. We compare the subsolar metallicity LMC OH/IR stars with carefully selected samples of more metal-rich OH/IR stars, also at known distances, in the Galactic Centre and Galactic bulge. We derive pulsation periods for eight of the bulge stars for the first time by using near-IR photometry from the Vista Variables in the Via Lactea survey. We have modelled our LMC OH/IR stars and developed an empirical method of deriving gas-to-dust ratios and mass-loss rates by scaling the models to the results from maser profiles. We have done this also for samples in the Galactic Centre and bulge and derived a new mass-loss prescription which includes luminosity, pulsation period, and gas-to-dust ratio dot{M} = 1.06^{+3.5}_{-0.8} × }10^{-5 (L/10^4 L_{⊙})^{0.9± 0.1}(P/500 {d})^{0.75± 0.3} (r_gd/200)^{-0.03± 0.07} M⊙ yr-1. The tightest correlation is found between mass-loss rate and luminosity. We find that the gas-to-dust ratio has little effect on the mass-loss of oxygen-rich AGB stars and RSGs within the Galaxy and the LMC. This suggests that the mass-loss of oxygen-rich AGB stars and RSGs is (nearly) independent of metallicity between a half and twice solar.

  3. The wind speeds, dust content, and mass-loss rates of evolved AGB and RSG stars at varying metallicity

    CERN Document Server

    Goldman, Steven R; Zijlstra, Albert A; Green, James A; Wood, Peter R; Nanni, Ambra; Imai, Hiroshi; Whitelock, Patricia A; Matsuura, Mikako; Groenewegen, Martin A T; Gómez, José F

    2016-01-01

    We present the results of our survey of 1612 MHz circumstellar OH maser emission from asymptotic giant branch (AGB) stars and red supergiants (RSGs) in the Large Magellanic Cloud. We have discovered four new circumstellar maser sources in the LMC, and increased the number of reliable wind speeds from IR stars in the LMC from 5 to 13. Using our new wind speeds, as well as those from Galactic sources, we have derived an updated relation for dust driven winds: $v_{exp} \\propto Z L^{0.4}$. We compare the sub-solar metallicity LMC OH/IR stars with carefully selected samples of more metal-rich OH/IR stars, also at known distances, in the Galactic Centre and Galactic Bulge. For 8 of the Bulge stars we derive pulsation periods for the first time, using near-IR photometry from the VVV survey. We have modeled our LMC OH/IR stars and developed an empirical method of deriving gas-to-dust ratios and mass loss rates by scaling the models to the results from maser profiles. We have done this also for samples in the Galactic...

  4. A systematic experimental study on the evaporation rate of supercooled water droplets at subzero temperatures and varying relative humidity

    Science.gov (United States)

    Ruberto, S.; Reutzsch, J.; Roth, N.; Weigand, B.

    2017-05-01

    Supercooled water droplets (SWD) are present in clouds at high altitude and subjected to very low temperatures and high relative humidity. These droplets exist in a metastable state. The understanding of the evaporation of SWD at these extreme conditions is of high interest to understand rain, snow, and hail generating mechanisms in clouds. This paper focuses on the experimental results of the measurements of the evaporation rates β of supercooled water droplets. For this purpose, single SWDs are trapped by means of optical levitation. During the evaporation process, the elastically scattered light in the forward regime is recorded and evaluated. Experiments have been performed for different relative humidities φ at three constant ambient temperatures, namely, {T_∞}=268.15; 263.15; 253.15 {{K}} ({t_∞} = -5; -10; -20°C). The experimental data agrees well with direct numerical simulations (DNS) carried out with the in-house code Free Surface 3D (FS3D) and shows that the use of a simplified model is permissible for these ambient conditions.

  5. The effect of varying the number of response alternatives in rating scales: experimental evidence from intra-individual effects.

    Science.gov (United States)

    Maydeu-Olivares, Alberto; Kramp, Uwe; García-Forero, Carlos; Gallardo-Pujol, David; Coffman, Donna

    2009-05-01

    Despite a hundred years of questionnaire testing, no consensus has been reached on the optimal number of response alternatives in rating scales. Differences in prior research may have been due to the use of various psychometric models (classical test theory, item factor analysis, and item response theory) and different performance criteria (reliability, convergent/discriminant validity, and internal structure of the questionnaire). Furthermore, previous empirical studies on this issue have tackled the experimental design from a between-subjects perspective, thus ignoring intra-individual effects. In contrast with this approach, we propose a within-subjects experimental design and a comprehensive statistical methodology using structural equation models for studying all of these aspects simultaneously, therefore increasing statistical power. To illustrate the method, two personality questionnaires were examined using a repeated measures design. Results indicated that as the number of response alternatives increased, (1) internal consistency increased, (2) there was no effect on convergent validity, and (3) goodness of fit worsened. Finally, the article assesses the practical consequences of this research for the design of future personality questionnaires.

  6. Components of Particle Emissions from Light-Duty Spark-Ignition Vehicles with Varying Aromatic Content and Octane Rating in Gasoline.

    Science.gov (United States)

    Short, Daniel Z; Vu, Diep; Durbin, Thomas D; Karavalakis, Georgios; Asa-Awuku, Akua

    2015-09-01

    Typical gasoline consists of varying concentrations of aromatic hydrocarbons and octane ratings. However, their impacts on particulate matter (PM) such as black carbon (BC) and water-soluble and insoluble particle compositions are not well-defined. This study tests seven 2012 model year vehicles, which include one port fuel injection (PFI) configured hybrid vehicle, one PFI vehicle, and six gasoline direct injection (GDI) vehicles. Each vehicle was driven on the Unified transient testing cycle (UC) using four different fuels. Three fuels had a constant octane rating of 87 with varied aromatic concentrations at 15%, 25%, and 35%. A fourth fuel with higher octane rating, 91, contained 35% aromatics. BC, PM mass, surface tension, and water-soluble organic mass (WSOM) fractions were measured. The water-insoluble mass (WIM) fraction of the vehicle emissions was estimated. Increasing fuel aromatic content increases BC emission factors (EFs) of transient cycles. BC concentrations were higher for the GDI vehicles than the PFI and hybrid vehicles, suggesting a potential climate impact for increased GDI vehicle production. Vehicle steady-state testing showed that the hygroscopicity of PM emissions at high speeds (70 mph; κ > 1) are much larger than emissions at low speeds (30 mph; κ emissions. Both aromatic content and vehicle speed increase the amount of hygroscopic material found in particle emissions.

  7. The integral pulse frequency modulation model with time-varying threshold: application to heart rate variability analysis during exercise stress testing.

    Science.gov (United States)

    Bailón, Raquel; Laouini, Ghailen; Grao, César; Orini, Michele; Laguna, Pablo; Meste, Olivier

    2011-03-01

    In this paper, an approach for heart rate variability analysis during exercise stress testing is proposed based on the integral pulse frequency modulation (IPFM) model, where a time-varying threshold is included to account for the nonstationary mean heart rate. The proposed technique allows the estimation of the autonomic nervous system (ANS) modulating signal using the methods derived for the IPFM model with constant threshold plus a correction, which is shown to be needed to take into account the time-varying mean heart rate. On simulations, this technique allows the estimation of the ANS modulation on the heart from the beat occurrence time series with lower errors than the IPFM model with constant threshold (1.1% ± 1.3% versus 15.0% ± 14.9%). On an exercise stress testing database, the ANS modulation estimated by the proposed technique is closer to physiology than that obtained from the IPFM model with constant threshold, which tends to overestimate the ANS modulation during the recovery and underestimate it during the initial rest.

  8. Optimization of linear alkylbenzene sulfonate (LAS) degradation in UASB reactors by varying bioavailability of LAS, hydraulic retention time and specific organic load rate.

    Science.gov (United States)

    Okada, Dagoberto Y; Delforno, Tiago P; Esteves, Andressa S; Sakamoto, Isabel K; Duarte, Iolanda C S; Varesche, Maria B A

    2013-01-01

    Degradation of linear alkylbenzene sulfonate (LAS) in UASB reactors was optimized by varying the bioavailability of LAS based on the concentration of biomass in the system (1.3-16 g TS/L), the hydraulic retention time (HRT), which was operated at 6, 35 or 80 h, and the concentration of co-substrates as specific organic loading rates (SOLR) ranging from 0.03-0.18 g COD/g TVS.d. The highest degradation rate of LAS (76%) was related to the lowest SOLR (0.03 g COD/g TVS.d). Variation of the HRT between 6 and 80 h resulted in degradation rates of LAS ranging from 18% to 55%. Variation in the bioavailability of LAS resulted in discrete changes in the degradation rates (ranging from 37-53%). According to the DGGE profiles, the archaeal communities exhibited greater changes than the bacterial communities, especially in biomass samples that were obtained from the phase separator. The parameters that exhibited more influence on LAS degradation were the SOLR followed by the HRT.

  9. Predictors and causes of unplanned re-operations in outpatient plastic surgery: a multi-institutional analysis of 6749 patients using the 2011 NSQIP database.

    Science.gov (United States)

    Lim, Seokchun; Jordan, Sumanas W; Jain, Umang; Kim, John Y S

    2014-08-01

    Studies that evaluate the predictors and causes of unplanned re-operation in outpatient plastic surgery. This study retrospectively reviewed the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) and identified all plastic surgery outpatient cases performed in 2011. Multiple logistic regression analysis was utilised to identify independent risk factors and causes of unplanned reoperations. Of the 6749 outpatient plastic surgery cases identified, there were 125 (1.9%) unplanned re-operations (UR). Regression analysis demonstrated that body mass index (BMI, OR = 1.041, 95% CI = 1.019-1.065), preoperative open wound/wound infection (OR = 3.498, 95% CI = 1.593-7.678), American Society of Anesthesiologists (ASA) class 3 (OR = 2.235, 95% CI = 1.048-4.765), and total work relative value units (RVU, OR = 1.014, 95% CI = 1.005-1.024) were significantly predictive of UR. Additionally, the presence of any complication was significantly associated with UR (OR = 15.065, 95% CI = 5.705-39.781). In an era of outcomes-driven medicine, unplanned re-operation is a critical quality indicator for ambulatory plastic surgery facilities. The identified risk factors will aid in surgical planning and risk adjustment.

  10. A Novel Time-Varying Spectral Filtering Algorithm for Reconstruction of Motion Artifact Corrupted Heart Rate Signals During Intense Physical Activities Using a Wearable Photoplethysmogram Sensor

    Directory of Open Access Journals (Sweden)

    Seyed M. A. Salehizadeh

    2015-12-01

    Full Text Available Accurate estimation of heart rates from photoplethysmogram (PPG signals during intense physical activity is a very challenging problem. This is because strenuous and high intensity exercise can result in severe motion artifacts in PPG signals, making accurate heart rate (HR estimation difficult. In this study we investigated a novel technique to accurately reconstruct motion-corrupted PPG signals and HR based on time-varying spectral analysis. The algorithm is called Spectral filter algorithm for Motion Artifacts and heart rate reconstruction (SpaMA. The idea is to calculate the power spectral density of both PPG and accelerometer signals for each time shift of a windowed data segment. By comparing time-varying spectra of PPG and accelerometer data, those frequency peaks resulting from motion artifacts can be distinguished from the PPG spectrum. The SpaMA approach was applied to three different datasets and four types of activities: (1 training datasets from the 2015 IEEE Signal Process. Cup Database recorded from 12 subjects while performing treadmill exercise from 1 km/h to 15 km/h; (2 test datasets from the 2015 IEEE Signal Process. Cup Database recorded from 11 subjects while performing forearm and upper arm exercise. (3 Chon Lab dataset including 10 min recordings from 10 subjects during treadmill exercise. The ECG signals from all three datasets provided the reference HRs which were used to determine the accuracy of our SpaMA algorithm. The performance of the SpaMA approach was calculated by computing the mean absolute error between the estimated HR from the PPG and the reference HR from the ECG. The average estimation errors using our method on the first, second and third datasets are 0.89, 1.93 and 1.38 beats/min respectively, while the overall error on all 33 subjects is 1.86 beats/min and the performance on only treadmill experiment datasets (22 subjects is 1.11 beats/min. Moreover, it was found that dynamics of heart rate variability

  11. A Novel Time-Varying Spectral Filtering Algorithm for Reconstruction of Motion Artifact Corrupted Heart Rate Signals During Intense Physical Activities Using a Wearable Photoplethysmogram Sensor

    Science.gov (United States)

    Salehizadeh, Seyed M. A.; Dao, Duy; Bolkhovsky, Jeffrey; Cho, Chae; Mendelson, Yitzhak; Chon, Ki H.

    2015-01-01

    Accurate estimation of heart rates from photoplethysmogram (PPG) signals during intense physical activity is a very challenging problem. This is because strenuous and high intensity exercise can result in severe motion artifacts in PPG signals, making accurate heart rate (HR) estimation difficult. In this study we investigated a novel technique to accurately reconstruct motion-corrupted PPG signals and HR based on time-varying spectral analysis. The algorithm is called Spectral filter algorithm for Motion Artifacts and heart rate reconstruction (SpaMA). The idea is to calculate the power spectral density of both PPG and accelerometer signals for each time shift of a windowed data segment. By comparing time-varying spectra of PPG and accelerometer data, those frequency peaks resulting from motion artifacts can be distinguished from the PPG spectrum. The SpaMA approach was applied to three different datasets and four types of activities: (1) training datasets from the 2015 IEEE Signal Process. Cup Database recorded from 12 subjects while performing treadmill exercise from 1 km/h to 15 km/h; (2) test datasets from the 2015 IEEE Signal Process. Cup Database recorded from 11 subjects while performing forearm and upper arm exercise. (3) Chon Lab dataset including 10 min recordings from 10 subjects during treadmill exercise. The ECG signals from all three datasets provided the reference HRs which were used to determine the accuracy of our SpaMA algorithm. The performance of the SpaMA approach was calculated by computing the mean absolute error between the estimated HR from the PPG and the reference HR from the ECG. The average estimation errors using our method on the first, second and third datasets are 0.89, 1.93 and 1.38 beats/min respectively, while the overall error on all 33 subjects is 1.86 beats/min and the performance on only treadmill experiment datasets (22 subjects) is 1.11 beats/min. Moreover, it was found that dynamics of heart rate variability can be

  12. A Novel Time-Varying Spectral Filtering Algorithm for Reconstruction of Motion Artifact Corrupted Heart Rate Signals During Intense Physical Activities Using a Wearable Photoplethysmogram Sensor.

    Science.gov (United States)

    Salehizadeh, Seyed M A; Dao, Duy; Bolkhovsky, Jeffrey; Cho, Chae; Mendelson, Yitzhak; Chon, Ki H

    2015-12-23

    Accurate estimation of heart rates from photoplethysmogram (PPG) signals during intense physical activity is a very challenging problem. This is because strenuous and high intensity exercise can result in severe motion artifacts in PPG signals, making accurate heart rate (HR) estimation difficult. In this study we investigated a novel technique to accurately reconstruct motion-corrupted PPG signals and HR based on time-varying spectral analysis. The algorithm is called Spectral filter algorithm for Motion Artifacts and heart rate reconstruction (SpaMA). The idea is to calculate the power spectral density of both PPG and accelerometer signals for each time shift of a windowed data segment. By comparing time-varying spectra of PPG and accelerometer data, those frequency peaks resulting from motion artifacts can be distinguished from the PPG spectrum. The SpaMA approach was applied to three different datasets and four types of activities: (1) training datasets from the 2015 IEEE Signal Process. Cup Database recorded from 12 subjects while performing treadmill exercise from 1 km/h to 15 km/h; (2) test datasets from the 2015 IEEE Signal Process. Cup Database recorded from 11 subjects while performing forearm and upper arm exercise. (3) Chon Lab dataset including 10 min recordings from 10 subjects during treadmill exercise. The ECG signals from all three datasets provided the reference HRs which were used to determine the accuracy of our SpaMA algorithm. The performance of the SpaMA approach was calculated by computing the mean absolute error between the estimated HR from the PPG and the reference HR from the ECG. The average estimation errors using our method on the first, second and third datasets are 0.89, 1.93 and 1.38 beats/min respectively, while the overall error on all 33 subjects is 1.86 beats/min and the performance on only treadmill experiment datasets (22 subjects) is 1.11 beats/min. Moreover, it was found that dynamics of heart rate variability can be

  13. Input-Output Approach to Control for Fuzzy Markov Jump Systems With Time-Varying Delays and Uncertain Packet Dropout Rate.

    Science.gov (United States)

    Zhang, Lixian; Ning, Zepeng; Shi, Peng

    2015-11-01

    This paper is concerned with H∞ control problem for a class of discrete-time Takagi-Sugeno fuzzy Markov jump systems with time-varying delays under unreliable communication links. It is assumed that the data transmission between the plant and the controller are subject to randomly occurred packet dropouts satisfying Bernoulli distribution and the dropout rate is uncertain. Based on a fuzzy-basis-dependent and mode-dependent Lyapunov function, the existence conditions of the desired H∞ state-feedback controllers are derived by employing the scaled small gain theorem such that the closed-loop system is stochastically stable and achieves a guaranteed H∞ performance. The gains of the controllers are constructed by solving a set of linear matrix inequalities. Finally, a practical example of robot arm is provided to illustrate the performance of the proposed approach.

  14. Effect of estradiol, vitamin A, E and selenium treatment with varying sexual rest period on recovery rate in cross-bred cows with chronic endometritis

    Directory of Open Access Journals (Sweden)

    Dipyaman Sengupta

    2013-04-01

    Full Text Available Aim:This work was done to study the effect of vitamin A, E and Se with varying sexual rest period in cross-bred cows with chronic endometritis. Materials and Methods: Cross-bred cows (n=396 from different villages of West Bengal with purulent or muco-purulent discharge with a history of infertility and repeat breeding for 3 to 6 months were chosen for the present study. These cows received uterine wash with lugol's iodine, intra-uterine and parenteral antibiotics and de-worming as general treatment. They were then divided into six groups viz. SR12 × EV (n=59, SR12 × Control (n=67, SR21 × EV (n=65, SR21 × Control (n=70, SR24 × EV (n=66, SR24 × Control (n=69 receiving sexual rest of 12 (SR12, 21 (SR21 and 24 (SR24 days with (EV group or without (control estradiol + vitamin A, E and Se. Results: The results indicate that the recovery rate of EV and control group was 76.27 % and 37.31 % respectively (P<0.01 in SR 12, 72.31 % and 47.14 % respectively (P<0.01 in SR 21 and 92.41 % and 63.77 % respectively (P<0.01 in SR 24. SR 24 showed significantly better (P<0.01 recovery rate compared to SR 12 and SR 21. Lowest recovery and conception rate of EV and control group in SR 12 might be due to insufficient time for the recovery of endometrium. Conclusion: The results indicate that parenteral and intra-uterine antibiotics had synergistic effect with estradiol, vitamin A, E and Se treatment in recovery from endometritis, though a minimum time interval is required for complete recovery of the endometrium for best conception rate. [Vet World 2013; 6(2.000: 106-108

  15. Therapeutically optimized rates of drug release can be achieved by varying the drug-to-lipid ratio in liposomal vincristine formulations.

    Science.gov (United States)

    Johnston, Michael J W; Semple, Sean C; Klimuk, Sandra K; Edwards, Katarina; Eisenhardt, Merete L; Leng, Esther C; Karlsson, Göran; Yanko, Daniel; Cullis, Pieter R

    2006-01-01

    The anti-tumor efficacy of liposomal formulations of cell cycle dependent anticancer drugs is critically dependent on the rates at which the drugs are released from the liposomes. Previous work on liposomal formulations of vincristine have shown increasing efficacy for formulations with progressively slower release rates. Recent work has also shown that liposomal formulations of vincristine with higher drug-to-lipid (D/L) ratios exhibit reduced release rates. In this work, the effects of very high D/L ratios on vincristine release rates are investigated, and the antitumor efficacy of these formulations characterized in human xenograft tumor models. It is shown that the half-times (T(1/2)) for vincristine release from egg sphingomyelin/cholesterol liposomes in vivo can be adjusted from T(1/2) = 6.1 h for a formulation with a D/L of 0.025 (wt/wt) to T(1/2) = 117 h (extrapolated) for a formulation with a D/L ratio of 0.6 (wt/wt). The increase in drug retention at the higher D/L ratios appears to be related to the presence of drug precipitates in the liposomes. Variations in the D/L ratio did not affect the circulation lifetimes of the liposomal vincristine formulations. The relationship between drug release rates and anti-tumor efficacy was evaluated using a MX-1 human mammary tumor model. It was found that the antitumor activity of the liposomal vincristine formulations increased as D/L ratio increased from 0.025 to 0.1 (wt/wt) (T(1/2) = 6.1-15.6 h respectively) but decreased at higher D/L ratios (D/L = 0.6, wt/wt) (T(1/2) = 117 h). Free vincristine exhibited the lowest activity of all formulations examined. These results demonstrate that varying the D/L ratio provides a powerful method for regulating drug release and allows the generation of liposomal formulations of vincristine with therapeutically optimized drug release rates.

  16. Re-operation of residual ventricular septal defect in 12 cases%残余室间隔缺损的再手术治疗12例

    Institute of Scientific and Technical Information of China (English)

    胡晓峰; 周运乾; 曹庆亨; 邱兆崑

    2001-01-01

    Objective To analyze the causation, surgical indications and pivotal points in reoperation of residual ventricular septal defect (VSD). Methods Collecting the clinical data of 12 cases of reoperated residual VSD in this hospital from 1988 to 1998 and investigating into insight of their causation, surgical indications and keys elements of reoperation in residual VSD. Results This group consisted of 12 patients of whom 8 were operated in this hospital from 1977 to 1997, and 4 were operated in other hospital. The re-operative rate of VSD in our hospital was 0.18 %.The defects in the first operation were 8 cases of simple VSD and 3 tetralogy of Fallot. The mean interval between the two operations was 4.1 years (5 months-12 years). Residual shunting in 10 patients were adjacent to the base of anterior and septal leaflets of tricuspid valve. The mean longitudinal diameter of residual VSD was 1.2 cm(0.3~2.5 cm).Three patients died after reoperation. Causes of death included low cardiac output syndrome, cardiac arrhythmia and cardiac tamponade. Conclusion 1. The common location of residual VSD is around the base of anterior and septal leaflets of tricuspid valve, this area involves some important structures like aortic valve and AV bundle which are not easily exposed. 2. Adequate exposure of entire VSD margin is the key element to avoid leakage by laceration. 3. Early re-operation is required for all residual VSD with diameter above 0.5 cm. 4. The key points of reoperation are timely operation, atrial incisional approach, patch repairment and careful hemostasis.%目的分析残余室间隔缺损(VSD)的发生原因、防治措施、手术指征和手术要点。方法对12例施行残余VSD再手术治疗患者的发生原因、预防措施、手术指征和手术要点进行分析。结果 12例中8例首次手术于1977年至1997年在我院施行,4例在外院施行,我院VSD再手术率为0.18%。首次手术时单纯VSD 9例,法洛四联症(TOF)3

  17. Varying Constants

    CERN Document Server

    Damour, Thibault Marie Alban Guillaume

    2003-01-01

    We review some string-inspired theoretical models which incorporate a correlated spacetime variation of coupling constants while remaining naturally compatible both with phenomenological constraints coming from geochemical data (Oklo; Rhenium decay) and with present equivalence principle tests. Barring unnatural fine-tunings of parameters, a variation of the fine-structure constant as large as that recently ``observed'' by Webb et al. in quasar absorption spectra appears to be incompatible with these phenomenological constraints. Independently of any model, it is emphasized that the best experimental probe of varying constants are high-precision tests of the universality of free fall, such as MICROSCOPE and STEP. Recent claims by Bekenstein that fine-structure-constant variability does not imply detectable violations of the equivalence principle are shown to be untenable.

  18. Spatially and temporally varying Quaternary uplift rates of the Gerecse Hills, Northern Pannonian Basin, using dated geomorphological horizons in the Danube valley

    Science.gov (United States)

    Ruszkiczay-Rüdiger, Zsófia; Fodor, László; Csillag, Gábor; Braucher, Régis; Kele, Sándor; Novothny, Ágnes; Thamó-Bozsó, Edit; Virág, Attila; Molnár, Gábor; Madarász, Balázs; Aster Team

    2016-04-01

    The assessment of Quaternary vertical deformation rates of uplifted, low altitude hilly regions is based mainly on the dating of paleo-surfaces that can be related to reference levels through several stages of landscape evolution. Regarding the Gerecse Hills (NE part of the Transdanubian Range, Hungary), situated to the south of the incised Danube River the all-time base-level of the river provides a suitable reference level, because the intracontinental setting of the study area makes it insensitive of the global sea level changes. The terrace sequences of the Hungarian part of the Danube valley preserve a record of varying tectonic uplift rates along the river course and throughout several climate stages. The Gerecse Hills consists mainly of Triassic carbonatic rocks and a thin Paleogene and Neogene siliciclastic cover. The Danube is escorted by a set of Quaternary river terraces and higher planation surfaces, which may be of Pliocene age. The terraces are covered by alluvial sediments frequently capped by travertine and/or loess. To establish the chronology of these terraces, we rely on U-series data of travertines and on new in situ produced cosmogenic nuclides data combined with luminescence (OSL and postIR-IRSL) ages from the lower terraces. In situ produced cosmogenic 10Be concentrations were measured in samples distributed along vertical depth profiles to enable the determination of both the exposure duration and the denudation rate at each studied locality. We used Monte Carlo approach to model the denudation rate-corrected exposure ages. Burial age determinations were performed using cosmogenic 26Al/10Be nuclide ratios. Post-IR IRSL measurements were carried out on K-feldspar and OSL measurements on quartz grains to determine the ages of sediment deposition. The highest dated horizon (˜115 m above the river) provided a preliminary burial age of ˜2.7 Ma, which is in accordance with the possible time span of sedimentation deduced from the occurrence of

  19. Modeling Population Spike Trains with Specified Time-Varying Spike Rates, Trial-to-Trial Variability, and Pairwise Signal and Noise Correlations.

    Science.gov (United States)

    Lyamzin, Dmitry R; Macke, Jakob H; Lesica, Nicholas A

    2010-01-01

    As multi-electrode and imaging technology begin to provide us with simultaneous recordings of large neuronal populations, new methods for modeling such data must also be developed. Here, we present a model for the type of data commonly recorded in early sensory pathways: responses to repeated trials of a sensory stimulus in which each neuron has it own time-varying spike rate (as described by its PSTH) and the dependencies between cells are characterized by both signal and noise correlations. This model is an extension of previous attempts to model population spike trains designed to control only the total correlation between cells. In our model, the response of each cell is represented as a binary vector given by the dichotomized sum of a deterministic "signal" that is repeated on each trial and a Gaussian random "noise" that is different on each trial. This model allows the simulation of population spike trains with PSTHs, trial-to-trial variability, and pairwise correlations that match those measured experimentally. Furthermore, the model also allows the noise correlations in the spike trains to be manipulated independently of the signal correlations and single-cell properties. To demonstrate the utility of the model, we use it to simulate and manipulate experimental responses from the mammalian auditory and visual systems. We also present a general form of the model in which both the signal and noise are Gaussian random processes, allowing the mean spike rate, trial-to-trial variability, and pairwise signal and noise correlations to be specified independently. Together, these methods for modeling spike trains comprise a potentially powerful set of tools for both theorists and experimentalists studying population responses in sensory systems.

  20. Net carbon dioxide exchange rates and predicted growth patterns in Alstroemeria Jacqueline' at varying irradiances, carbon dioxide concentrations, and air temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Leonardos, E.D.; Tsujita, M.J.; Grodzinski, B. (Univ. of Guelph, Ontario (Canada). Dept. of Horticultural Science)

    1994-11-01

    The influence of irradiance, CO[sub 2] concentration, and air temperature on leaf and whole-plant net C exchange rate (NCER) of Alstroemeria Jacqueline' was studied. At ambient CO[sub 2], leaf net photosynthesis was maximum at irradiances above 600 [mu]mol[center dot]m[sup [minus]2][center dot]s[sup [minus]1] photosynthetically active radiation (PAR), while whole-plant NCER required 1,200 [mu]mol[center dot]m[sup [minus]2][center dot]s[sup [minus]1] PAR to be saturated. Leaf and whole-plant NCERs were doubled under CO[sub 2] enrichment of 1,500 to 2,000 [mu]l CO[sub 2]/liter. Leaf and whole-plant NCERs declined as temperature increased from 20 to 35 C. Whereas the optimum temperature range for leaf net photosynthesis was 17 to 23 C, whole-plant NCER, even at high light and high CO[sub 2], declined above 12 C. Dark respiration of leaves and whole plants increased with a Q[sub 10] of [approx] 2 at 15 to 35 C. In an analysis of day effects, irradiance, CO[sub 2] concentration, and temperature contributed 58%, 23%, and 14%, respectively, to the total variation in NCER explained by a second-order polynomial model (R[sup 2] = 0.85). Interactions among the factors accounted for 4% of the variation in day C assimilation. The potential whole-plant growth rates during varying greenhouse day and night temperature regimes were predicted for short- and long-day scenarios. The data are discussed with the view of designing experiments to test the importance of C gain in supporting flowering and high yield during routine harvest of Alstroemeria plants under commercial greenhouse conditions.

  1. Preliminary findings in the heart rate variability and haemorheology response to varied frequency and duration of walking in women 65-74 yr with type 2 diabetes.

    Science.gov (United States)

    Simmonds, Michael J; Minahan, Clare L; Serre, Kevin R; Gass, Gregory C; Marshall-Gradisnik, Sonya M; Haseler, Luke J; Sabapathy, Surendran

    2012-01-01

    Heart rate variability (HRV) and haemorheology adaptations to 12 wk of varied-dose treadmill walking were investigated in women aged 65-74 yr with type 2 diabetes. Subjects were randomly allocated into two groups where exercise frequency and session duration were manipulated (Group 1: 2 × 60 min·wk(-1) or Group 2: 4 × 30 min·wk(-1)), but intensity and accumulated weekly duration of exercise were consistent between groups (100% gas-exchange threshold; 120 min·wk(-1)). Twelve weeks of exercise training significantly improved peak oxygen uptake, time to exhaustion, and gas-exchange threshold (p exercise group. Exercise training did not significantly change glycaemic control or body mass. Red blood cell (RBC) aggregation and RBC deformability significantly decreased (p exercise-only intervention and that exercise training improved RBC aggregation without a concomitant improvement in glycaemic control. The accumulated weekly exercise duration may be the most important training component for the prescription of exercise in older women with type 2 diabetes.

  2. The study of organic removal efficiency and halophilic bacterial mixed liquor characteristics in a membrane bioreactor treating hypersaline produced water at varying organic loading rates.

    Science.gov (United States)

    Sharghi, Elham Abdollahzadeh; Bonakdarpour, Babak

    2013-12-01

    In this study the organic pollutant removal performance and the mixed liquor characteristics of a membrane bioreactor (MBR), employing a halophilic bacterial consortium, for the treatment of hypersaline synthetic produced water - at varying organic loading rates (OLR) from 0.3 to 2.6 kg CODm(-3)d(-1) - were considered. The oil and grease (O&G) and COD removal efficiency were 95-99% and 83-93%, respectively with only transient O&G (mainly polycyclic aromatic hydrocarbons) and soluble microbial products accumulation being observed. With increasing OLR, in the range 0.9-2.6 kg COD m(-3)d(-1), as a result of change in both extracellular polymeric substances (EPS) and zeta potential, bioflocculating ability improved but the compressibility of the flocs decreased resulting in the occurrence of EPS bulking at the highest OLR studied. The latter resulted in a change in the rheology of the mixed liquor from Newtonian to non-Newtonian and the occurrence of significant membrane fouling. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Evaluation Of Factors Influencing On Causes Of Prosthetic Valve Re-operation And Early Postoperative Survival Tehran Emam hospital (1991-2001

    Directory of Open Access Journals (Sweden)

    Rahmani Reaza

    2003-06-01

    Full Text Available Prosthetic valve re-operation has greater mortality and morbidity than primary valve replacement. By recognition of factors influencing on causes of redo operation and preoperative survival, one can select appropriate prosthesis at primary valve replacement and when operation performed at appropriate time, surgical risk can be reduced."nMethods and Materials: Two hundred patients that underwent prosthetic valve re-operation from October 1991 through November 2001 were included in this study. There were 68 men and 132 women with the mean age of 42:tl 1.8 years. Structural failure was the commonest cause of bio-prosthesis replacement (93%. Valve thrombosis was the common cause of mechanical valve replacement (32%. Age younger Than 50 (P= 0.01 and interval after the first implantation more than 10 years (P= 0.01 affected bio-prosthesis degeneration."nResults: Atrial fibrillation (P<0.01, Older age especially more than 40 (P<0.05 and mitral position (P<0.01 affected mechanical valve thrombosis. Cross clamp time (P= 0.005, Tricuspid insufficiency (P = 0.001, NYHA IV (P = 0.005 and emergent operation (P= 0.001 were independent determinants of hospital mortality."nConclusion: In conclusion, in patients with more than 10-years life expectancy and age younger than 50, mechanical valve can be selected for primary valve replacement. If operation performed before patients reach deteriorated condition, preoperative survival would be excellent.

  4. Therapeutic analysis of high-dose-rate {sup 192}Ir vaginal cuff brachytherapy for endometrial cancer using a cylindrical target volume model and varied cancer cell distributions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hualin, E-mail: hualin.zhang@northwestern.edu; Donnelly, Eric D.; Strauss, Jonathan B. [Department of Radiation Oncology, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, Chicago, Illinois 60611 (United States); Qi, Yujin [Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522 (Australia)

    2016-01-15

    Purpose: To evaluate high-dose-rate (HDR) vaginal cuff brachytherapy (VCBT) in the treatment of endometrial cancer in a cylindrical target volume with either a varied or a constant cancer cell distributions using the linear quadratic (LQ) model. Methods: A Monte Carlo (MC) technique was used to calculate the 3D dose distribution of HDR VCBT over a variety of cylinder diameters and treatment lengths. A treatment planning system (TPS) was used to make plans for the various cylinder diameters, treatment lengths, and prescriptions using the clinical protocol. The dwell times obtained from the TPS were fed into MC. The LQ model was used to evaluate the therapeutic outcome of two brachytherapy regimens prescribed either at 0.5 cm depth (5.5 Gy × 4 fractions) or at the vaginal mucosal surface (8.8 Gy × 4 fractions) for the treatment of endometrial cancer. An experimentally determined endometrial cancer cell distribution, which showed a varied and resembled a half-Gaussian distribution, was used in radiobiology modeling. The equivalent uniform dose (EUD) to cancer cells was calculated for each treatment scenario. The therapeutic ratio (TR) was defined by comparing VCBT with a uniform dose radiotherapy plan in term of normal cell survival at the same level of cancer cell killing. Calculations of clinical impact were run twice assuming two different types of cancer cell density distributions in the cylindrical target volume: (1) a half-Gaussian or (2) a uniform distribution. Results: EUDs were weakly dependent on cylinder size, treatment length, and the prescription depth, but strongly dependent on the cancer cell distribution. TRs were strongly dependent on the cylinder size, treatment length, types of the cancer cell distributions, and the sensitivity of normal tissue. With a half-Gaussian distribution of cancer cells which populated at the vaginal mucosa the most, the EUDs were between 6.9 Gy × 4 and 7.8 Gy × 4, the TRs were in the range from (5.0){sup 4} to (13

  5. Therapeutic analysis of high-dose-rate (192)Ir vaginal cuff brachytherapy for endometrial cancer using a cylindrical target volume model and varied cancer cell distributions.

    Science.gov (United States)

    Zhang, Hualin; Donnelly, Eric D; Strauss, Jonathan B; Qi, Yujin

    2016-01-01

    To evaluate high-dose-rate (HDR) vaginal cuff brachytherapy (VCBT) in the treatment of endometrial cancer in a cylindrical target volume with either a varied or a constant cancer cell distributions using the linear quadratic (LQ) model. A Monte Carlo (MC) technique was used to calculate the 3D dose distribution of HDR VCBT over a variety of cylinder diameters and treatment lengths. A treatment planning system (TPS) was used to make plans for the various cylinder diameters, treatment lengths, and prescriptions using the clinical protocol. The dwell times obtained from the TPS were fed into MC. The LQ model was used to evaluate the therapeutic outcome of two brachytherapy regimens prescribed either at 0.5 cm depth (5.5 Gy × 4 fractions) or at the vaginal mucosal surface (8.8 Gy × 4 fractions) for the treatment of endometrial cancer. An experimentally determined endometrial cancer cell distribution, which showed a varied and resembled a half-Gaussian distribution, was used in radiobiology modeling. The equivalent uniform dose (EUD) to cancer cells was calculated for each treatment scenario. The therapeutic ratio (TR) was defined by comparing VCBT with a uniform dose radiotherapy plan in term of normal cell survival at the same level of cancer cell killing. Calculations of clinical impact were run twice assuming two different types of cancer cell density distributions in the cylindrical target volume: (1) a half-Gaussian or (2) a uniform distribution. EUDs were weakly dependent on cylinder size, treatment length, and the prescription depth, but strongly dependent on the cancer cell distribution. TRs were strongly dependent on the cylinder size, treatment length, types of the cancer cell distributions, and the sensitivity of normal tissue. With a half-Gaussian distribution of cancer cells which populated at the vaginal mucosa the most, the EUDs were between 6.9 Gy × 4 and 7.8 Gy × 4, the TRs were in the range from (5.0)(4) to (13.4)(4) for the radiosensitive normal

  6. Therapeutic analysis of high-dose-rate 192Ir vaginal cuff brachytherapy for endometrial cancer using a cylindrical target volume model and varied cancer cell distributions

    Science.gov (United States)

    Zhang, Hualin; Donnelly, Eric D.; Strauss, Jonathan B.; Qi, Yujin

    2016-01-01

    Purpose: To evaluate high-dose-rate (HDR) vaginal cuff brachytherapy (VCBT) in the treatment of endometrial cancer in a cylindrical target volume with either a varied or a constant cancer cell distributions using the linear quadratic (LQ) model. Methods: A Monte Carlo (MC) technique was used to calculate the 3D dose distribution of HDR VCBT over a variety of cylinder diameters and treatment lengths. A treatment planning system (TPS) was used to make plans for the various cylinder diameters, treatment lengths, and prescriptions using the clinical protocol. The dwell times obtained from the TPS were fed into MC. The LQ model was used to evaluate the therapeutic outcome of two brachytherapy regimens prescribed either at 0.5 cm depth (5.5 Gy × 4 fractions) or at the vaginal mucosal surface (8.8 Gy × 4 fractions) for the treatment of endometrial cancer. An experimentally determined endometrial cancer cell distribution, which showed a varied and resembled a half-Gaussian distribution, was used in radiobiology modeling. The equivalent uniform dose (EUD) to cancer cells was calculated for each treatment scenario. The therapeutic ratio (TR) was defined by comparing VCBT with a uniform dose radiotherapy plan in term of normal cell survival at the same level of cancer cell killing. Calculations of clinical impact were run twice assuming two different types of cancer cell density distributions in the cylindrical target volume: (1) a half-Gaussian or (2) a uniform distribution. Results: EUDs were weakly dependent on cylinder size, treatment length, and the prescription depth, but strongly dependent on the cancer cell distribution. TRs were strongly dependent on the cylinder size, treatment length, types of the cancer cell distributions, and the sensitivity of normal tissue. With a half-Gaussian distribution of cancer cells which populated at the vaginal mucosa the most, the EUDs were between 6.9 Gy × 4 and 7.8 Gy × 4, the TRs were in the range from (5.0)4 to (13.4)4 for the

  7. Economic Effects of Reservoir Re-operation Policy in the Rio Grande/Bravo for Sustainable Human and Environmental Water Management

    Science.gov (United States)

    Ortiz Partida, J. P.; Sandoval Solis, S.; Lane, B.

    2015-12-01

    A central challenge of integrated water management is the design and implementation of policies to allocate water to both humans and the environment in a sustainable manner. This study uses the results from a reach-scale water-planning model to quantify and compare the economic benefits of two water management policies: (1) a business as usual (Baseline) policy and (2) a proposed reservoir re-operation policy to provide environmental flows (EFs). Results show that the EF policy would increase water supply profit, slightly decrease recreational activities profit, and reduce costs from flood damage and environmental restoration compared to the Baseline policy. In addition to supporting ecological objectives, the proposed EF policy would increase the economic benefits of water management objectives.

  8. RELIABILITY ANALYSIS FOR A REPAIRABLE PARALLEL SYSTEM WITH TIMEVARYING FAILURE RATES%失效率随时间变化的可修的并联系统的可靠性分析

    Institute of Scientific and Technical Information of China (English)

    汤胜道; 汪凤泉

    2005-01-01

    To solve a real problem:how to calculate the reliability of a system with time v arying failure rates in industry systems,this paper studies a model for the load sharing parallel system with timevarying failure rates,and obtains calculati ng formulas of reliability and availability of the system by solving differentia l equations.In this paper,the failure rates are expressed in polynomial configur ation.The constant,linear and Weibull failure rate are in their special form.The polynomial failure rates provide flexibility in modeling the practical timevar ying failure rates.

  9. Comparing spatially varying coefficient models: a case study examining violent crime rates and their relationships to alcohol outlets and illegal drug arrests

    Science.gov (United States)

    Wheeler, David C.; Waller, Lance A.

    2009-03-01

    In this paper, we compare and contrast a Bayesian spatially varying coefficient process (SVCP) model with a geographically weighted regression (GWR) model for the estimation of the potentially spatially varying regression effects of alcohol outlets and illegal drug activity on violent crime in Houston, Texas. In addition, we focus on the inherent coefficient shrinkage properties of the Bayesian SVCP model as a way to address increased coefficient variance that follows from collinearity in GWR models. We outline the advantages of the Bayesian model in terms of reducing inflated coefficient variance, enhanced model flexibility, and more formal measuring of model uncertainty for prediction. We find spatially varying effects for alcohol outlets and drug violations, but the amount of variation depends on the type of model used. For the Bayesian model, this variation is controllable through the amount of prior influence placed on the variance of the coefficients. For example, the spatial pattern of coefficients is similar for the GWR and Bayesian models when a relatively large prior variance is used in the Bayesian model.

  10. 食管闭锁术后食管再手术的临床探讨%Re-operation after the primary repair for patients with esophageal atresia

    Institute of Scientific and Technical Information of China (English)

    沈淳; 郑珊; 肖现民

    2012-01-01

    Objective The aim of the study is to summarize the clinical experience of re-operation after esophageal atresia (EA) primary repair.Methods From 2005.6 ~ 2011.7,8 cases of reoperation were performed in our hospital after primary esophageal atresia repair.There were 6 males to 2 females.Patients' ages ranged from 6m to 52 m 7 cases were Gross type Ⅲ and 1was Gross type Ⅰ.Thepresenting complaints were coughing after feeding or feeding difficulty.6 cases had TEF recurrence and 2 cases had severe anastomotic stricturerefractory to dilatation.All cases had pre-operative esophagogram and esophagoscopic examinations.4 also had bronchoscopy.Single lung ventilation was required in 6 patients during procedure.All cases had access via right-sided thoracotomy.Results The average re-operation time was 3.5 h,and the average stay in hospital was 25 d.All patients stayed in PICU for several days.Follow-up period ranged from 1-72 m.No anastomotic leakage or recurrence of fistula occurred.1patient needed anastomotic dilatation once.Conclusions Factors such as not cutting the fistula in primary repair,high tension,leakage and inflammation couldall cause TEFR and AS.TEFR and/or serious AS are the indications for re-operation after EA primary repair.Esophagoscopy and bronchoscopy before re-operation are very important for TEFR diagnosis and treatment.Unilateral lung ventilation during anaesthesia procedure can provide more security for patients.In general,prognosis was good after re-operation.%目的 分析总结食管闭锁术后食管再手术的临床经验.方法 2005年6月至2011年7月,8例接受食管闭锁术后食管再手术患儿,男6例,女2例.再手术时年龄6~52个月.7例GrossⅢ型,1例Gross Ⅰ型.再手术前表现为进食后呛咳及进食困难.6例食管气管瘘复发,2例严重狭窄反复扩张无效.8例行食管造影和食管镜检查瘘管及狭窄情况;4例行支气管镜检查.6例术中单肺通气.8例经右胸再手术,切断、缝扎

  11. Effect of estradiol, vitamin A, E and selenium treatment with varying sexual rest period on recovery rate in cross-bred cows with chronic endometritis

    OpenAIRE

    Dipyaman Sengupta; Pramod R. Nandi

    2013-01-01

    Aim:This work was done to study the effect of vitamin A, E and Se with varying sexual rest period in cross-bred cows with chronic endometritis. Materials and Methods: Cross-bred cows (n=396) from different villages of West Bengal with purulent or muco-purulent discharge with a history of infertility and repeat breeding for 3 to 6 months were chosen for the present study. These cows received uterine wash with lugol's iodine, intra-uterine and parenteral antibiotics and de-worming as general tr...

  12. Estimating pesticide sampling rates by the polar organic chemical integrative sampler (POCIS) in the presence of natural organic matter and varying hydrodynamic conditions.

    Science.gov (United States)

    Charlestra, Lucner; Amirbahman, Aria; Courtemanch, David L; Alvarez, David A; Patterson, Howard

    2012-10-01

    The polar organic chemical integrative sampler (POCIS) was calibrated to monitor pesticides in water under controlled laboratory conditions. The effect of natural organic matter (NOM) on the sampling rates (R(s)) was evaluated in microcosms containing 0.05). However, flow velocity and turbulence significantly increased the sampling rates of the pesticides in the FTS and SBE compared to the QBE (p POCIS deployed in stagnant and turbulent environmental systems without correction for NOM. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Nitrous oxide emissions in Midwest US maize production vary widely with band-injected N fertilizer rates, timing and nitrapyrin presence

    Science.gov (United States)

    Burzaco, Juan P.; Smith, Doug R.; Vyn, Tony J.

    2013-09-01

    Nitrification inhibitors have the potential to reduce N2O emissions from maize fields, but optimal results may depend on deployment of integrated N fertilizer management systems that increase yields achieved per unit of N2O lost. A new micro-encapsulated formulation of nitrapyrin for liquid N fertilizers became available to US farmers in 2010. Our research objectives were to (i) assess the impacts of urea-ammonium nitrate (UAN) management practices (timing, rate and nitrification inhibitor) and environmental variables on growing-season N2O fluxes and (ii) identify UAN treatment combinations that both reduce N2O emissions and optimize maize productivity. Field experiments near West Lafayette, Indiana in 2010 and 2011 examined three N rates (0, 90 and 180 kg N ha-1), two timings (pre-emergence and side-dress) and presence or absence of nitrapyrin. Mean cumulative N2O-N emissions (Q10 corrected) were 0.81, 1.83 and 3.52 kg N2O-N ha-1 for the rates of 0, 90 and 180 kg N ha-1, respectively; 1.80 and 2.31 kg N2O-N ha-1 for pre-emergence and side-dress timings, respectively; and 1.77 versus 2.34 kg N2O-N ha-1 for with and without nitrapyrin, respectively. Yield-scaled N2O-N emissions increased with N rates as anticipated (averaging 167, 204 and 328 g N2O-N Mg grain-1 for the 0, 90 and 180 kg N ha-1 rates), but were 22% greater with the side-dress timing than the pre-emergence timing (when averaged across N rates and inhibitor treatments) because of environmental conditions following later applications. Overall yield-scaled N2O-N emissions were 22% lower with nitrapyrin than without the inhibitor, but these did not interact with N rate or timing.

  14. Variation in the Slope Coefficient of the Fama Regression for Testing Uncovered Interest Rate Parity: Evidence from Fixed and Time-varying Coefficient Approaches

    NARCIS (Netherlands)

    C. de Koning (Camiel); S. Straetmans

    1997-01-01

    textabstractWe investigate the potential presence of time variation in the coefficients of the ''Fama regression'' for Uncovered Interest Rate Parity. We implement coefficient constancy tests, rolling regression techniques, and stochastic coefficient models based on state space modelling. Among six

  15. Variation in the Slope Coefficient of the Fama Regression for Testing Uncovered Interest Rate Parity: Evidence from Fixed and Time-varying Coefficient Approaches

    NARCIS (Netherlands)

    C. de Koning (Camiel); S. Straetmans

    1997-01-01

    textabstractWe investigate the potential presence of time variation in the coefficients of the ''Fama regression'' for Uncovered Interest Rate Parity. We implement coefficient constancy tests, rolling regression techniques, and stochastic coefficient models based on state space modelling. Among six

  16. Standardized laryngeal videostroboscopic rating : Differences between untrained and trained male and female subjects, and effects of varying sound intensity, fundamental frequency, and age

    NARCIS (Netherlands)

    Sulter, AM; Schutte, HK; Miller, DG

    To determine the influence of the factors gender, vocal training, sound intensity, pitch, and aging on vocal function, videolaryngostroboscopic images of 214 subjects, subdivided according to gender and status of vocal training, were evaluated by three judges with standardized rating scales,

  17. Estimates of exclusive breastfeeding rates among mother-infant dyads in Quetzaltenango, Guatemala, vary according to interview method and time frame.

    Science.gov (United States)

    van Beusekom, Ilse; Vossenaar, Marieke; Montenegro-Bethancourt, Gabriela; Doak, Colleen M; Solomons, Noel W

    2013-06-01

    The World Health Organization (WHO) recommends exclusive breastfeeding, defined as receiving only breastmilk, through the first 6 months of life to optimize survival, health, and development. To assess exclusive and predominant breastfeeding rates, as defined by WHO, in a sample of Guatemalan infants using three dietary assessment methods. Mothers of 156 infants (78 boys and 78 girls) in the 6th month of life, attending a public health center in Quetzaltenango, an urban area located in the Highlands of Guatemala, were recruited. A single face-to-face interview was performed to assess infant dietary intake using three methods: previous day dietary recall (as suggested by WHO), current feeding practices, and recall of feeding practices since birth. Based on the previous day dietary recall method, exclusive breastfeeding was reported by 87 (56%) of the mothers. Exclusive breastfeeding rates were much lower when estimated by current feeding practices questions (20%) and even lower when based on recall of feeding practices since birth (9%). The sum of exclusive and predominant breastfeeding (full breastfeeding) rates was 58%, 49%, and 31% based on previous day dietary recall, current feeding practices, and recall of feeding practices since birth, respectively. The WHO method of dietary assessment, based solely on the previous day dietary recall, overestimates the exclusive breastfeeding rate compared with recall of feeding practices since birth. In our population sample, adherence to the WHO guidelines for feeding in the first semester of infancy was less than ideal and in need of strengthening.

  18. Effects of pre-incubation of eggs in fresh water and varying sperm concentration on fertilization rate in sterlet sturgeon, Acipenser ruthenus.

    Science.gov (United States)

    Siddique, Mohammad Abdul Momin; Butts, Ian Anthony Ernest; Psenicka, Martin; Linhart, Otomar

    2015-08-01

    Standardization of fertilization protocols for sterlet Acipenser ruthenus is crucial for improving reproductive techniques and for conservation purposes. Our objectives were to determine the number of sperm (tested 430,000:1, 43,000:1, 4300:1, 430:1 sperm to egg) required to fertilize eggs and explore how pre-incubation of eggs in freshwater for 0min, 0.5min, 1min, and 10min interacts with different sperm ratios. Fertilization success ranged from 29.7% at 430:1 to 84.2% at 430,000:1. Pre-incubation time had no effect on fertilization success at 430,000:1 and 43,000:1 sperm to egg ratios, while it was significant at the 4300:1 and 430:1 ratios. The use of adequate experimental suboptimal sperm to egg ratio revealed a positive effect of pre-incubation time, such that at the 430:1 ratio, 0.5min pre-incubation increased the fertilization rate than 10min. At 0min pre-incubation the proportion of fertilized eggs increased at the 430,000:1 ratio, while at 1min fertilization increased at the 4300:1 ratio. At the 10min pre-incubation time, fertilization increased at the 43,000:1 ratio. Moreover, at the 0.5min pre-incubation time, the 43,000:1 ratio increased the fertilization rate than the 430:1 ratio. Generally, for 430:1 ratio, the fertilization rate is lower than in control. Transmission electron microscopy showed that pre-incubation of eggs in water for fertilization can enhance fertilization rate of sterlet. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Optimization of Ligninolytic Enzyme Activity and Production Rate with Ceriporiopsis subvermispora for Application in Bioremediation by Varying Submerged Media Composition and Growth Immobilization Support

    Directory of Open Access Journals (Sweden)

    Janja Babič

    2012-09-01

    Full Text Available Response surface methodology (central composite design of experiments was employed to simultaneously optimize enzyme production and productivities of two ligninolytic enzymes produced by Ceriporiopsis subvermispora. Concentrations of glucose, ammonium tartrate and Polysorbate 80 were varied to establish the optimal composition of liquid media (OLM, where the highest experimentally obtained activities and productivities were 41 U L−1 and 16 U L−1 day−1 for laccase (Lac, and 193 U L−1 and 80 U L−1 day−1 for manganese peroxidase (MnP. Considering culture growth in OLM on various types of immobilization support, the best results were obtained with 1 cm beech wood cubes (BWCM. Enzyme activities in culture filtrate were 152 U L−1 for Lac and 58 U L−1 for MnP, since the chemical composition of this immobilization material induced higher Lac activity. Lower enzyme activities were obtained with polyurethane foam. Culture filtrates of OLM and BWCM were applied for dye decolorization. Remazol Brilliant Blue R (RBBR was decolorized faster and more efficiently than Copper(IIphthalocyanine (CuP with BWCM (80% and 60%, since Lac played a crucial role. Decolorization of CuP was initially faster than that of RBBR, due to higher MnP activities in OLM. The extent of decolorization after 14 h was 60% for both dyes.

  20. Optimization of ligninolytic enzyme activity and production rate with Ceriporiopsis subvermispora for application in bioremediation by varying submerged media composition and growth immobilization support.

    Science.gov (United States)

    Babič, Janja; Likozar, Blaž; Pavko, Aleksander

    2012-01-01

    Response surface methodology (central composite design of experiments) was employed to simultaneously optimize enzyme production and productivities of two ligninolytic enzymes produced by Ceriporiopsis subvermispora. Concentrations of glucose, ammonium tartrate and Polysorbate 80 were varied to establish the optimal composition of liquid media (OLM), where the highest experimentally obtained activities and productivities were 41 U L(-1) and 16 U L(-1) day(-1) for laccase (Lac), and 193 U L(-1) and 80 U L(-1) day(-1) for manganese peroxidase (MnP). Considering culture growth in OLM on various types of immobilization support, the best results were obtained with 1 cm beech wood cubes (BWCM). Enzyme activities in culture filtrate were 152 U L(-1) for Lac and 58 U L(-1) for MnP, since the chemical composition of this immobilization material induced higher Lac activity. Lower enzyme activities were obtained with polyurethane foam. Culture filtrates of OLM and BWCM were applied for dye decolorization. Remazol Brilliant Blue R (RBBR) was decolorized faster and more efficiently than Copper(II)phthalocyanine (CuP) with BWCM (80% and 60%), since Lac played a crucial role. Decolorization of CuP was initially faster than that of RBBR, due to higher MnP activities in OLM. The extent of decolorization after 14 h was 60% for both dyes.

  1. Comparative effect of partial root-zone drying and deficit irrigation on incidence of blossom-end rot in tomato under varied calcium rates

    DEFF Research Database (Denmark)

    Sun, Yanqi; Feng, Hao; Liu, Fulai

    2013-01-01

    This study investigated the comparative effects of reduced irrigation regimes—partial root-zone drying (PRD) and conventional deficit irrigation (DI)—on the incidence of blossom-end rot (BER) in tomato (Solanum lycopersicum L.) under three Ca-fertilization rates: 0, 100, and 200mg Ca kg–1 soil...... xylem sap abscisic acid concentration, lower stomatal conductance, and higher plant water status in the PRD in relation to the DI plants might have contributed to the increased fruit Ca uptake, and could have reduced BER development in tomato fruits. Therefore, under conditions with limited freshwater...... resources, application of PRD irrigation could be a promising approach for saving water and for preventing BER development in tomatoes....

  2. Effect of air pollution on respiratory tract diseases in small children. Morbidity rate in residential areas with varying degrees of severe pollution

    Energy Technology Data Exchange (ETDEWEB)

    Muehling, P.; Bory, J.; Haupt, H.

    1984-09-13

    In a retrospective study of hospitalized patients (children aged between 0 and 4 years) covering four years the dependence of the incidence of croup (infectious laryngitis) and obstructive bronchitis on air pollution was investigated. For this reason the incidence of morbidity in residential areas with various levels of SO/sub 2/ and sedimenting dust were compared. The results show a definitive connection between a high level of SO/sub 2/ and dust, respectively and a high rate of morbidity. This connection was particularly marked in areas with simultaneous high levels of both SO/sub 2/ and dust. The effects of confounding factors, such as infection incidence, meteorological influences, distances from hospital, social status, especially the percentage of foreign guest worker families and population density were investigated and separated from air pollution effects.

  3. Rates of molecular evolution vary in vertebrates for insulin-like growth factor-1 (IGF-1), a pleiotropic locus that regulates life history traits.

    Science.gov (United States)

    Sparkman, Amanda M; Schwartz, Tonia S; Madden, Jill A; Boyken, Scott E; Ford, Neil B; Serb, Jeanne M; Bronikowski, Anne M

    2012-08-01

    Insulin-like growth factor-1 (IGF-1) is a member of the vertebrate insulin/insulin-like growth factor/relaxin gene family necessary for growth, reproduction, and survival at both the cellular and organismal level. Its sequence, protein structure, and function have been characterized in mammals, birds, and fish; however, a notable gap in our current knowledge of the function of IGF-1 and its molecular evolution is information in ectothermic reptiles. To address this disparity, we sequenced the coding region of IGF-1 in 11 reptile species-one crocodilian, three turtles, three lizards, and four snakes. Complete sequencing of the full mRNA transcript of a snake revealed the Ea-isoform, the predominant isoform of IGF-1 also reported in other vertebrate groups. A gene tree of the IGF-1 protein-coding region that incorporated sequences from diverse vertebrate groups showed similarity to the species phylogeny, with the exception of the placement of Testudines as sister group to Aves, due to their high nucleotide sequence similarity. In contrast, long-branch lengths indicate more rapid divergence in IGF-1 among lizards and snakes. Additionally, lepidosaurs (i.e., lizards and snakes) had higher rates of non-synonymous:synonymous substitutions (dN/dS) relative to archosaurs (i.e., birds and crocodilians) and turtles. Tests for positive selection on specific codons within branches and evaluation of the changes in the amino acid properties, suggested positive selection in lepidosaurs on the C domain of IGF-1, which is involved in binding affinity to the IGF-1 receptor. Predicted structural changes suggest that major alterations in protein structure and function may have occurred in reptiles. These data propose new insights into the molecular co-evolution of IGF-1 and its receptors, and ultimately the evolution of IGF-1's role in regulating life-history traits across vertebrates.

  4. Phosphorus extracted by ion exchange resins and mehlich-1 from oxisols (latosols treated with different phosphorus rates and sources for varied soil-source contact periods

    Directory of Open Access Journals (Sweden)

    Irio Fernando de Freitas

    2013-06-01

    Full Text Available Despite the large number of studies addressing the quantification of phosphorus (P availability by different extraction methods, many questions remain unanswered. The aim of this paper was to compare the effectiveness of the extractors Mehlich-1, Anionic Resin (AR and Mixed Resin (MR, to determine the availability of P under different experimental conditions. The laboratory study was arranged in randomized blocks in a [(3 x 3 x 2 + 3] x 4 factorial design, with four replications, testing the response of three soils with different texture: a very clayey Red Latosol (LV, a sandy clay loam Red Yellow Latosol (LVA, and a sandy loam Yellow Latosol (LA, to three sources (triple superphosphate, reactive phosphate rock from Gafsa-Tunisia; and natural phosphate from Araxá-Minas Gerais at two P rates (75 and 150 mg dm-3, plus three control treatments (each soil without P application after four contact periods (15, 30, 60, and 120 days of the P sources with soil. The soil acidity of LV and LVA was adjusted by raising base saturation to 60 % with the application of CaCO3 and MgCO3 at a 4:1 molar ratio (LA required no correction. These samples were maintained at field moisture capacity for 30 days. After the contact periods, the samples were collected to quantify the available P concentrations by the three extractants. In general, all three indicated that the available P-content in soils was reduced after longer contact periods with the P sources. Of the three sources, this reduction was most pronounced for triple superphosphate, intermediate for reactive phosphate, while Araxá phosphate was least sensitive to the effect of time. It was observed that AR extracted lower P levels from all three soils when the sources were phosphate rocks, while MR extracted values close to Mehlich-1 in LV (clay and LVA (medium texture for reactive phosphate. For Araxá phosphate, much higher P values were determined by Mehlich-1 than by the resins, because of the acidity of

  5. [The longitudinal increase of the internal jugular vein and the upper v. cava as measured between the mastoid to the heart: parameter for timing the re-operation after ventriculocardiostomy (author's transl)].

    Science.gov (United States)

    Müke, R; Glashoff, M

    1976-04-01

    Some time after ventriculo-cardiostomy in children with hydrocephalus the cardiac catheter is retracting out of the right atrium into the upper veins due to the increase of body length during growth. This might endanger proper functioning of the valve. Therefore most authors are in favour of a prophylactic elongation of the catheter by re-operation. In order to roughly predict the time for re-operation we measured course of the catheter in 4120 children. As a basis for long time supervision of children with this shunt operation we thus propose a curve of length increase of the blood vessels concerned, based on our data, in connection with the known curve of length increase of the body.

  6. Analytical correlation between varying corrosion parameters and corrosion rate of Al-4.5Cu/10%ZrSiO{sub 4} composite in hydrochloric acid by rare earth chloride

    Energy Technology Data Exchange (ETDEWEB)

    Oloche, O.B.; Yaro, S.A. [Department of Metallurgical Engineering Ahmadu Bello University, Zaria (Nigeria); Okafor, E.G. [Department of Metallurgical Engineering Ahmadu Bello University, Zaria (Nigeria)], E-mail: ekeneokafor@yahoo.com

    2009-03-20

    The effect of varying temperature, time and inhibitor concentration on the corrosion rate of Al-4.5Cu/ZrSiO{sub 4} composite in 0.5 M hydrochloric acid without and with lanthanide chloride salt have been investigated. 10%ZrSiO{sub 4} was used for the production of the Al-4.5Cu/zircon sand composite. The time, temperature and concentration of inhibitor were varied in the range of 6-10 h at 2 h interval, 30-75 deg. C at 15 deg. C interval and 250-1000 ppm at 250 ppm interval respectively. Factorial design, standard deviation, effect of variables at 95% confidence interval and Arrhenius kinetics approach were used to correlate the corrosion parameter and corrosion rate. Results show that increase in temperature, inhibitor concentration above 250 ppm and decrease in time enhance corrosion rate. Also, temperature and anti-corrosion agent concentration are the most important control parameters. The kinetic and statistical approaches were in good agreement.

  7. Research on Time-varying Impacts of Impulse Response between China's Exchange Rate Market and Stock Market%中国汇市与股市间的时变冲击影响研究

    Institute of Scientific and Technical Information of China (English)

    曹广喜

    2013-01-01

    The study on the dynamic relationship between stock market and exchange rate market can provide important reference value to the macro-financial policy setting and micro-investment decision making. Taking the long memory character of financial time series into account, long memory dynamic VAR (Vector Auto-regression) model is proposed to improve the time-varying parameter VAR model stated by Primiceri (2005). Based on the long memory dynamic VAR model, dynamic relationships of impulse response among China's exchange rate market and stock markets in the United States and China are empirical analyzed by using the daily close prices of RMB nominal exchange rate and stock prices of Shanghai stock exchange composite index and S&P 500 index from August 1, 2005 to October 20, 2011. The results show that long memory characteristics exist in China's exchange rate market and stock market while anti-persistence feature exists in the US stock market and there is a significant directional impulse response of stock markets in the United States and China to RMB exchange rate shocks. These impulse responses present time-varying characteristics in the first three days with the characteristics of structural breaks and last about 7 days totally. The results also indicate that the time-varying characteristics of impulse response of stock markets to RMB exchange rate shocks is related to the RMB exchange rate mechanism reform in the short term and the drastic changes in financial environment in the long term.%股市和汇市的动态关系研究对于宏观金融政策制定和微观投资决策具有重要参考价值.针对金融时间序列长记忆特征,改进Primiceri时变VAR模型(向量自回归模型),给出长记忆动态VAR模型.基于2005年8月1日至2011年10月20日的人民币对美元汇率、中国上证综合指数和美国标普500指数的日价格数据,利用长记忆动态VAR模型实证分析中国汇市与中美股市问的动态冲击影响关

  8. An Efficient Time-Varying Filter for Detrending and Bandwidth Limiting the Heart Rate Variability Tachogram without Resampling: MATLAB Open-Source Code and Internet Web-Based Implementation

    Directory of Open Access Journals (Sweden)

    A. Eleuteri

    2012-01-01

    Full Text Available The heart rate variability (HRV signal derived from the ECG is a beat-to-beat record of RR intervals and is, as a time series, irregularly sampled. It is common engineering practice to resample this record, typically at 4 Hz, onto a regular time axis for analysis in advance of time domain filtering and spectral analysis based on the DFT. However, it is recognised that resampling introduces noise and frequency bias. The present work describes the implementation of a time-varying filter using a smoothing priors approach based on a Gaussian process model, which does not require data to be regular in time. Its output is directly compatible with the Lomb-Scargle algorithm for power density estimation. A web-based demonstration is available over the Internet for exemplar data. The MATLAB (MathWorks Inc. code can be downloaded as open source.

  9. An efficient time-varying filter for detrending and bandwidth limiting the heart rate variability tachogram without resampling: MATLAB open-source code and Internet web-based implementation.

    Science.gov (United States)

    Eleuteri, A; Fisher, A C; Groves, D; Dewhurst, C J

    2012-01-01

    The heart rate variability (HRV) signal derived from the ECG is a beat-to-beat record of RR intervals and is, as a time series, irregularly sampled. It is common engineering practice to resample this record, typically at 4 Hz, onto a regular time axis for analysis in advance of time domain filtering and spectral analysis based on the DFT. However, it is recognised that resampling introduces noise and frequency bias. The present work describes the implementation of a time-varying filter using a smoothing priors approach based on a Gaussian process model, which does not require data to be regular in time. Its output is directly compatible with the Lomb-Scargle algorithm for power density estimation. A web-based demonstration is available over the Internet for exemplar data. The MATLAB (MathWorks Inc.) code can be downloaded as open source.

  10. Assessment and management of biliary tract re-operation accompanied with hepatocirrhosis and portal hypertension%胆道多次手术合并肝硬化门静脉高压症的评估及处理

    Institute of Scientific and Technical Information of China (English)

    柏立山; 柴新群; 胡志坚; 冯贤松

    2011-01-01

    Objective To probe the assessment and management of biliary tract re-operation accompanied with hepatocirrhosis and portal hypertension. Methods The clinical data of 18 patients of bile duct re operation accompanied with hepatocirrhosis and portal hypertension from January 2005 to December 2008 were retro spectively analyzed. Results Of the 18 patients. 4 were grouped to Child A according to Child-Pugh classificalion. 10 were child B, another 4 were Child C. As to the causes of hepatoeirrhosis: 14 patients (77.8%)resulted from biliary cirrhosis. 2 posthepatitic cirrhosis. 2 schistosomiasis cirrhosis. Sixteen patients received simply hiliary tract re-operation. 2 received biliary tract re-operation with devascularization; the bleeding amount during operation was up to 800~1 600 mL. Three of whom had post operative complications: 1 with biliary fistula, I with intestinal fistula and 1 with upper gastrointestinal bleeding. The other patient died of multi-organ dysfunction in preoperative period. Conclusion To the patients of biliary tract re-operation accompanied with hepatocirrhosis and portal hypertension, surgical operation will get good results if the assessment of relevant pre-operative issues are enhanced and the appropriate treatments are executed. Child-Pugh classification is not appropriate to assess the patients of biliary tract re-operation accompanied with hepatocirrhosis and portal hypertension.%目的 探讨胆道多次手术同时合并肝硬化门静脉高压症的评估及处理.方法 回顾性分析2005年1月至2008年12月我院收治的18例胆道多次手术同时合并肝硬化门静脉高压症患者的临床资料.结果 18例胆道多次手术同时合并肝硬化门静脉高压症患者中,按照Child-Pugh分级,A级4例,B级10例,C级4例.肝硬化原因:胆汁性肝硬化14例(77.8%),肝炎后肝硬化2例,血吸虫性肝硬化2例.单独行胆道多次手术16例,联合行胆道多次手术和断流术2例;术中出血量达800

  11. Discussion on valve re-operative cases after cardiac valve replacement%关于心脏瓣膜置换术后再次瓣膜手术的探讨

    Institute of Scientific and Technical Information of China (English)

    宣海洋; 石开虎; 张飞; 徐盛松; 吴君旭; 曹炜; 龚文辉; 赵旭东

    2011-01-01

    Objective To summarize the results of valve re-operative cases after cardiac valve replacement, to find the better re-operative time, and to estimate the re-operative methods and influencing factors of the operation. Methods Thirteen valve re-operative cases after cardiac valve replacement from October 2008 to February 2010 were retrospectively studied. According to NYHA classification, 9 cases belonged to class Ⅳ, and only 4 cases belonged to class Ⅲ preoperatively. Mitral valve replacement (MVR)was performed in 7 cases, aortic valve replacement (AVR) in 3 cases, MVR + AVR in 3 cases. Results The early-stage postoperative mortality was 7.7%( 1/13),and the reason was low cardiac output syndrome. Two cases who underwent re-operation and re-intubation respectively after operation for hemorrhage were improved after treatment. Twelve cases were discharged in 3-6 weeks after heart valve surgery and all were followed up for 6-15 months. The cardiac function of all the discharged patients recovered well and no death occurred during follow-up. Conclusion The key factors to reduce the death of re-operation are improving preoperative heart function,setting up extracorporeal circulation as soon as possible,consummating myocardial preservation,perfecting operating skills,correcting low cardiac output syndrome in time and preventing complications.%目的 分析心脏瓣膜置换术后再次瓣膜手术的原因,探讨手术时机的选择、手术方法及对结果的影响因素.方法 对2008年10月至2010年2月心脏瓣膜置换术后再次瓣膜手术的13例患者进行回顾性分析,术前NYHA心功能Ⅲ级4例,Ⅳ级9例.单纯二尖瓣置换术7例,单纯主动脉瓣置换术3例,二尖瓣并主动脉瓣置换术3例.结果 术后早期死亡1例,病死率7.7%(1/13),死亡原因为术后低心排血量综合征.术后因出血二次开胸止血和再次气管插管各1例,经抢救治疗后均好转,12例患者均于3~6周出院.随访6~15

  12. Re-operation of tricuspid regurgitation after mitral valve replacement with rheumatic heart disease%风湿性心脏病二尖瓣置换术后三尖瓣返流的再手术治疗

    Institute of Scientific and Technical Information of China (English)

    罗又桥; 方海宁; 谭伟; 李树松; 曹辉庆; 赖纪昌

    2014-01-01

    Objective To analyze clinical manifestation and investigate therapy effect of re-operation of tricuspid regurgitation (TR) after mitral valve replacement with rheumatic heart disease.Methods Seventeen cases with rheumatic heart disease recurred TR after mitral valve replacement surgery,underwent tricuspid valve surgery again in the Third People's Hospital of Nanchang from January 2000 to December 2011.Of 17 cases,10cases underwent tricuspid valve annuloplasty including 1 case for pure De Vega plasty,9 cases for the valve leaflets forming + artificial valve ring forming.Another 7 cases underwent tricuspid valve replacement surgery including 4 cases for biological valve replacement and 3 cases for mechanical valve.Retrospective analyzed the clinical manifestations,treatment process and condition of prognosis.Results One case was with early postoperative deaths (5.88%,1717),and died of postoperative left ventricular failure.Three cases were postoperative low cardiac output syndrome,2 cases were renal insufficiency,and 2 cases were respiratory insufficiency,all those cases were successfully cured.Sixteen cases were followed up from 3 months to 9 years and 2 cases were lost.Of 14,2 cases were NYHA class Ⅰ,8 cases for grade Ⅱ,4 cases for grade Ⅲ.Conclusion After mitral valve replacement in patients with rheumatic heart disease,TR in patients with reoperation is a suitable choice.Reasonable surgical indications,timing of surgery and good perioperative management are the keys to improve the success rate of surgery.%目的 分析风湿性心脏病二尖瓣置换术后再发三尖瓣返流(TR)患者的临床特点、外科手术方法和疗效,总结围手术期处理经验.方法 2000年1月至2011年12月,17例风湿性心脏病二尖瓣置换术后再发三尖瓣返流的患者在我院接受单纯再次三尖瓣手术,行三尖瓣成形术10例,包括单纯DeVega成形术1例、瓣叶成形+人工瓣环成形9例;行三尖瓣置换术7例,其中置换生物瓣4

  13. Fluorosis varied treatment options

    OpenAIRE

    Sherwood I

    2010-01-01

    Fluorosis has been reported way back in 1901. The treatment options for fluorosis are varied depending upon individual cases. This article comes from Madurai in India where its surrounding towns are fluorosis-prone zones. The purpose of this article is to report various treatment options available for dental fluorosis; this is the first time that complete full mouth rehabilitation for dental fluorosis is being reported. This article also dwells on the need for the dentists to be aware of thei...

  14. O espectro da reoperação em cirurgia de coronária The spectrum os re-operation in coronary surgery

    Directory of Open Access Journals (Sweden)

    Jarbas J Dinkhuysen

    1989-04-01

    ção, angioplastia mal sucedida e presença de mamária prévia não causaram impacto decisivo na morbidade e na mortalidade desta série (P > 0,05.The authors present the results obtained in the first 30 day P.O. of 204 patients who underwent reoperations for coronary atherosclerosis. The interval between first and second operation varied from 1 month to 16.5 years. There was also two small groups of patients of third intervention and with associated cardiac lesions. The basic strategy consisted on anticoagulation, the aplication of the mammary arteries (one or two whenever possible, and revascularization as complete as possible. Most patients showed uneventfull evolution and a quarter of them presented some kind of non-fatal complication with good response to specific therapeutic measures. The overall mortality was about 9%. Patients with atherosclerotic lesions in native coronary circulation presented the greater morbidity, but in those with atherosclerotic lesions both in the grafts and coronary native circulation, the mortality was higher. Contrary to expectation, the younger group showed higher mortality, and the older group presented higher morbidity. The aplication of the IMA's on the reintervention does not add morbidity or mortality, but the concomitant correction of the associated cardiac pathologies represented a higher risk in the procedure. Recent myocardial infarction influenced also morbidity. The third intervention, failure transluminal angioplastic coronary dilatation and the presence of previous IMA does not exert deleterious impact on the morbidity or mortality.

  15. Fluorosis varied treatment options

    Directory of Open Access Journals (Sweden)

    Sherwood I

    2010-01-01

    Full Text Available Fluorosis has been reported way back in 1901. The treatment options for fluorosis are varied depending upon individual cases. This article comes from Madurai in India where its surrounding towns are fluorosis-prone zones. The purpose of this article is to report various treatment options available for dental fluorosis; this is the first time that complete full mouth rehabilitation for dental fluorosis is being reported. This article also dwells on the need for the dentists to be aware of their local indigenous pathologies to treat it in a better manner.

  16. Time Varying Feature Data

    Science.gov (United States)

    Echterhoff, J.; Simonis, I.; Atkinson, R.

    2012-04-01

    The infrastructure to gather, store and access information about our environment is improving and growing rapidly. The increasing amount of information allows us to get a better understanding of the current state of our environment, historical processes and to simulate and predict the future state of the environment. Finer grained spatial and temporal data and more reliable communications make it easier to model dynamic states and ephemeral features. The exchange of information within and across geospatial domains is facilitated through the use of harmonized information models. The Observations & Measurements (O&M) developed through OGC and standardised by ISO is an example of such a cross-domain information model. It is used in many domains, including meteorology, hydrology as well as the emergency management. O&M enables harmonized representation of common metadata that belong to the act of determining the state of a feature property, whether by sensors, simulations or humans. In addition to the resulting feature property value, information such as the result quality but especially the time that the result applies to the feature property can be represented. Temporal metadata is critical to modelling past and future states of a feature. The features, and the semantics of each property, are defined in domain specific Application Schema using the General Feature Model (GFM) from ISO 19109 and usually encoded following ISO 19136. However, at the moment these standards provide only limited support for the representation and handling of time varying feature data. Features like rivers, wildfires or gas plumes have a defined state - for example geographic extent - at any given point in time. To keep track of changes, a more complex model for example using time-series coverages is required. Furthermore, the representation and management of feature property value changes via the service interfaces defined by OGC and ISO - namely: WFS and WCS - would be rather complex

  17. varying elastic parameters distributions

    KAUST Repository

    Moussawi, Ali

    2014-12-01

    The experimental identication of mechanical properties is crucial in mechanics for understanding material behavior and for the development of numerical models. Classical identi cation procedures employ standard shaped specimens, assume that the mechanical elds in the object are homogeneous, and recover global properties. Thus, multiple tests are required for full characterization of a heterogeneous object, leading to a time consuming and costly process. The development of non-contact, full- eld measurement techniques from which complex kinematic elds can be recorded has opened the door to a new way of thinking. From the identi cation point of view, suitable methods can be used to process these complex kinematic elds in order to recover multiple spatially varying parameters through one test or a few tests. The requirement is the development of identi cation techniques that can process these complex experimental data. This thesis introduces a novel identi cation technique called the constitutive compatibility method. The key idea is to de ne stresses as compatible with the observed kinematic eld through the chosen class of constitutive equation, making possible the uncoupling of the identi cation of stress from the identi cation of the material parameters. This uncoupling leads to parametrized solutions in cases where 5 the solution is non-unique (due to unknown traction boundary conditions) as demonstrated on 2D numerical examples. First the theory is outlined and the method is demonstrated in 2D applications. Second, the method is implemented within a domain decomposition framework in order to reduce the cost for processing very large problems. Finally, it is extended to 3D numerical examples. Promising results are shown for 2D and 3D problems.

  18. Do loss to follow-up and death rates from ART care vary across primary health care facilities and hospitals in south Ethiopia? A retrospective follow-up study

    Directory of Open Access Journals (Sweden)

    Teshome W

    2015-05-01

    Full Text Available Wondu Teshome,1 Mehretu Belayneh,1 Mathewos Moges,1 Emebet Mekonnen,2 Misganu Endrias,2 Sinafiksh Ayele,2 Tebeje Misganaw,2 Mekonnen Shiferaw,2 Tigist Tesema2 1School of Public and Environmental Health, Hawassa University, 2Health Research and Technology Transfer Support Process, Southern Nations Nationalities and Peoples' Regional Health Bureau, Hawassa, Ethiopia Background: Decentralization and task shifting has significantly improved access to antiretroviral therapy (ART. Many studies conducted to determine the attrition rate in Ethiopia have not compared attrition rates between hospitals and health centers in a relatively recent cohort of patients. This study compared death and loss to follow-up (LTFU rates among ART patients in hospitals and health centers in south Ethiopia. Methods: Data routinely collected from patients aged older than 15 years who started ART between July 2011 and August 2012 in 20 selected health facilities (12 being hospitals were analyzed. The outcomes of interest were LTFU and death. The data were entered, cleaned, and analyzed using Statistical Package for the Social Sciences version 20.0 and Stata version 12.0. Competing-risk regression models were used. Results: The service years of the facilities were similar (median 8 and 7.5 for hospitals and health centers, respectively. The mean patient age was 33.7±9.6 years. The median baseline CD4 count was 179 (interquartile range 93–263 cells/mm3. A total of 2,356 person-years of observation were made with a median follow-up duration of 28 (interquartile range 22–31 months; 24.6% were either dead or LTFU, resulting in a retention rate of 75.4%. The death rates were 3.0 and 1.5 and the LTFU rate were 9.0 and 10.9 per 100 person-years of observation in health centers and hospitals, respectively. The competing-risk regression model showed that the gap between testing and initiation of ART, body mass index, World Health Organization clinical stage, isoniazid prophylaxis

  19. Test procedure for variable rate fertilizer on coffee = Método para avaliação de aplicação de fertilizantes em taxa variável em café

    Directory of Open Access Journals (Sweden)

    Gustavo Di Chiacchio Faulin

    2010-10-01

    Full Text Available The objective was to develop and test a procedure for applying variable rates of fertilizers and evaluate yield response in coffee (Coffea arabica L. with regard to the application of phosphorus and potassium. The work was conducted during the 2004 season in a 6.4 ha field located in central São Paulo state. Two treatments were applied with alternating strips of fixed and variable rates during the whole season: one following the fertilizing procedures recommended locally, and the other based on a grid soil sampling. A prototype pneumatic fertilizer applicator was used, carrying two conveyor belts, one foreach row. Harvesting was done with a commercial harvester equipped with a customized volumetric yield monitor, separating the two treatments. Data were analyzed based on geostatistics, correlations and regressions. The procedure showed to be feasible and effective. The area that received fertilizer applications at a variable rate showed a 34% yield increase compared to the area that received a fixed rate. The variable rate fertilizer resulted in a savings of 23% in phosphate fertilizer and a 13% increase in potassium fertilizer, when compared to fixed rate fertilizer. Yield in 2005, the year after the variable rate treatments, still presented residual effect from treatments carried out during the previous cycle.O objetivo foi desenvolver um procedimento para avaliar a resposta daprodutividade de café (Coffea arabica L., a partir da aplicação de fósforo e potássio. O trabalho foi conduzido durante o ciclo produtivo do ano de 2004 em um talhão de 6,4 ha localizado na região central do Estado de São Paulo. Foram aplicados dois tratamentos emlinhas alternadas de plantas com doses fixas e variadas, um seguindo procedimentos e recomendações locais e o outro com base na amostragem de solo em grade. Para a aplicação dos fertilizantes, foi utilizado o protótipo de uma adubadora com duas esteiras independentes, uma para cada linha de plantas

  20. Stable large-scale CO2 storage in defiance of an energy system based on renewable energy - Modelling the impact of varying CO2 injection rates on reservoir behavior

    Science.gov (United States)

    Bannach, Andreas; Hauer, Rene; Martin, Streibel; Stienstra, Gerard; Kühn, Michael

    2015-04-01

    The IPCC Report 2014 strengthens the need for CO2 storage as part of CCS or BECCS to reach ambitious climate goals despite growing energy demand in the future. The further expansion of renewable energy sources is a second major pillar. As it is today in Germany the weather becomes the controlling factor for electricity production by fossil fuelled power plants which lead to significant fluctuations of CO2-emissions which can be traced in injection rates if the CO2 were captured and stored. To analyse the impact of such changing injection rates on a CO2 storage reservoir. two reservoir simulation models are applied: a. An (smaller) reservoir model approved by gas storage activities for decades, to investigate the dynamic effects in the early stage of storage filling (initial aquifer displacement). b. An anticline structure big enough to accommodate a total amount of ≥ 100 Mega tons CO2 to investigate the dynamic effects for the entire operational life time of the storage under particular consideration of very high filling levels (highest aquifer compression). Therefore a reservoir model was generated. The defined yearly injection rate schedule is based on a study performed on behalf of IZ Klima (DNV GL, 2014). According to this study the exclusive consideration of a pool of coal-fired power plants causes the most intensive dynamically changing CO2 emissions and hence accounts for variations of a system which includes industry driven CO2 production. Besides short-term changes (daily & weekly cycles) seasonal influences are also taken into account. Simulation runs cover a variation of injection points (well locations at the top vs. locations at the flank of the structure) and some other largely unknown reservoir parameters as aquifer size and aquifer mobility. Simulation of a 20 year storage operation is followed by a post-operational shut-in phase which covers approximately 500 years to assess possible effects of changing injection rates on the long-term reservoir

  1. Chemical and microbiological water quality of subsurface agricultural drains during a field trial of liquid dairy manure effluent application rate and varying tillage practices, Upper Tiffin Watershed, southeastern Michigan

    Science.gov (United States)

    Haack, Sheridan Kidd; Duris, Joseph W.

    2008-01-01

    -water-quality single-sample criterion of 235 colony forming units per 100 milliliters in only 3 of 56 samples. Of these three samples, two were collected within 1 day post-LDME application from the treatment receiving 8,000 gal/acre LDME with no tillage (NT8000). The third sample was from the rolling-tine aerator treatment with 4,000 gal/acre LDME application rate after the first significant rainfall. Two wastewater chemicals and two bacterial genes (eaeA and stx1) detected in the LDME, but absent in field blank or pre-application samples, were detected in the 4-hour or 1-day postapplication NT8000 samples. No LDME-associated chemicals were detected in later samples from the NT8000 treatment, and none were detected in samples from other treatments after the first significant rainfall. Results of this field trial were somewhat equivocal with respect to the influence of LDME concentration and tillage practices on subsurface-drain water quality, both immediately after LDME application and in the longer term, after significant rainfall. Interpretation of study findings is limited by the fact that treatments were not replicated, and flow rate or discharge from the subsurface drains was not measured. Nevertheless, study results provide useful information about nutrient and bacteria concentrations in subsurface drains during the non-growing season. In addition, study results demonstrate some potential for the use of chemical and microbiological indicators of LDME transport to subsurface drains.

  2. Optimum size in grid soil sampling for variable rate application in site-specific management Tamanho ideal em grades de amostragem de solos para aplicação em taxa variável em manejo localizado

    Directory of Open Access Journals (Sweden)

    Marcos Rafael Nanni

    2011-06-01

    Full Text Available The importance of understanding spatial variability of soils is connected to crop management planning. This understanding makes it possible to treat soil not as a uniform, but a variable entity, and it enables site-specific management to increase production efficiency, which is the target of precision agriculture. Questions remain as the optimum soil sampling interval needed to make site-specific fertilizer recommendations in Brazil. The objectives of this study were: i to evaluate the spatial variability of the main attributes that influence fertilization recommendations, using georeferenced soil samples arranged in grid patterns of different resolutions; ii to compare the spatial maps generated with those obtained with the standard sampling of 1 sample ha-1, in order to verify the appropriateness of the spatial resolution. The attributes evaluated were phosphorus (P, potassium (K, organic matter (OM, base saturation (V% and clay. Soil samples were collected in a 100 × 100 m georeferenced grid. Thinning was performed in order to create a grid with one sample every 2.07, 2.88, 3.75 and 7.20 ha. Geostatistical techniques, such as semivariogram and interpolation using kriging, were used to analyze the attributes at the different grid resolutions. This analysis was performed with the Vesper software package. The maps created by this method were compared using the kappa statistics. Additionally, correlation graphs were drawn by plotting the observed values against the estimated values using cross-validation. P, K and V%, a finer sampling resolution than the one using 1 sample ha-1 is required, while for OM and clay coarser resolutions of one sample every two and three hectares, respectively, may be acceptable.A importância de compreender a variabilidade espacial do solo está conectada ao planejamento do manejo das culturas. Este entendimento faz com que seja possível tratar o solo não como uma entidade uniforme, mas variável, e permite o

  3. Bouncing universes with varying constants

    Energy Technology Data Exchange (ETDEWEB)

    Barrow, John D [DAMTP, Centre for Mathematical Sciences, Cambridge University, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Kimberly, Dagny [Theoretical Physics, Blackett Laboratory, Imperial College, Prince Consort Road, London SW7 2BZ (United Kingdom); Magueijo, Joao [Theoretical Physics, Blackett Laboratory, Imperial College, Prince Consort Road, London SW7 2BZ (United Kingdom)

    2004-09-21

    We investigate the behaviour of exact closed bouncing Friedmann universes in theories with varying constants. We show that the simplest BSBM varying alpha theory leads to a bouncing universe. The value of alpha increases monotonically, remaining approximately constant during most of each cycle, but increasing significantly around each bounce. When dissipation is introduced we show that in each new cycle the universe expands for longer and to a larger size. We find a similar effect for closed bouncing universes in Brans-Dicke theory, where G also varies monotonically in time from cycle to cycle. Similar behaviour occurs also in varying speed of light theories.

  4. Bouncing Universes with Varying Constants

    CERN Document Server

    Barrow, J D; Magueijo, J; Barrow, John D.; Kimberly, Dagny; Magueijo, Joao

    2004-01-01

    We investigate the behaviour of exact closed bouncing Friedmann universes in theories with varying constants. We show that the simplest BSBM varying-alpha theory leads to a bouncing universe. The value of alpha increases monotonically, remaining approximately constant during most of each cycle, but increasing significantly around each bounce. When dissipation is introduced we show that in each new cycle the universe expands for longer and to a larger size. We find a similar effect for closed bouncing universes in Brans-Dicke theory, where $G$ also varies monotonically in time from cycle to cycle. Similar behaviour occurs also in varying speed of light theories.

  5. Varying c and Particle Horizons

    CERN Document Server

    Chimento, L P; Pavón, D; Chimento, Luis P; Jakubi, Alejandro S; Pavon, Diego

    2001-01-01

    We explore what restrictions may impose the second law of thermodynamics on varying speed of light theories. We find that the attractor scenario solving the flatness problem is consistent with the generalized second law at late time.

  6. Stabilization of Slowly Varying Switched Linear Systems

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bing; LIANG Tong

    2012-01-01

    The stabilization problem of systems that switch among a finite set of slowly varying linear systems with arbitrary switching frequency is discussed.It is shown that if the entries of the pointwise stabilizing feedback gain matrix are continuously differentiable functions of the entries of the system coefficient matrices,then the closed-loop system is uniformly asymptotically stable if the rate of time variation of the system coefficient matrices is sufficiently small.

  7. Time-varying Crash Risk

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Feunoua, Bruno; Jeon, Yoontae

    We estimate a continuous-time model with stochastic volatility and dynamic crash probability for the S&P 500 index and find that market illiquidity dominates other factors in explaining the stock market crash risk. While the crash probability is time-varying, its dynamic depends only weakly on re...

  8. Mass Varying Neutrinos in Supernovae

    CERN Document Server

    Rossi-Torres, F; de Holanda, P C; Peres, O L G

    2010-01-01

    We study limits for the mass varying neutrino model, using constrains from supernova neutrinos placed by the r-process condition, $Y_e<0.5$. Also, we use this model in a supernova environment to study the regions of survival probability in the oscillation space parameter ($\\tan^2\\theta$ and $\\Delta m^2_0$), considering the channel $\

  9. Time-varying Crash Risk

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Feunoua, Bruno; Jeon, Yoontae

    We estimate a continuous-time model with stochastic volatility and dynamic crash probability for the S&P 500 index and find that market illiquidity dominates other factors in explaining the stock market crash risk. While the crash probability is time-varying, its dynamic depends only weakly...... on return variance once we include market illiquidity as an economic variable in the model....

  10. Esmaklassiline Karlovy Vary / Jaanus Noormets

    Index Scriptorium Estoniae

    Noormets, Jaanus

    2007-01-01

    Ilmar Raagi mängufilm "Klass" võitis 42. Karlovy Vary rahvusvahelise filmifestivalil kaks auhinda - ametliku kõrvalvõistlusprogrammi "East of the West" eripreemia "Special mention" ja Euroopa väärtfilmikinode keti Europa Cinemas preemia. Ka Asko Kase lühifilmi "Zen läbi prügi linastumisest ning teistest auhinnasaajatest ning osalejatest

  11. Optimistlik Karlovy Vary / Jaan Ruus

    Index Scriptorium Estoniae

    Ruus, Jaan, 1938-2017

    2007-01-01

    42. Karlovy Vary rahvusvahelise filmifestivali auhinnatud filmidest (žürii esimees Peter Bart). Kristallgloobuse sai Islandi-Saksamaa "Katseklaasilinn" (režii Baltasar Kormakur), parimaks režissööriks tunnistati norralane Bard Breien ("Negatiivse mõtlemise kunst"). Austraallase Michael James Rowlandi "Hea õnne teekond" sai žürii eripreemia

  12. Eestlased Karlovy Varys / J. R.

    Index Scriptorium Estoniae

    J. R.

    2007-01-01

    Ilmar Raagi mängufilm "Klass" osaleb 42. Karlovy Vary rahvusvahelise filmifestivali võistlusprogrammis "East of the West" ja Asko Kase lühimängufilm "Zen läbi prügi" on valitud festivali kõrvalprogrammi "Forum of Independents"

  13. Esmaklassiline Karlovy Vary / Jaanus Noormets

    Index Scriptorium Estoniae

    Noormets, Jaanus

    2007-01-01

    Ilmar Raagi mängufilm "Klass" võitis 42. Karlovy Vary rahvusvahelise filmifestivalil kaks auhinda - ametliku kõrvalvõistlusprogrammi "East of the West" eripreemia "Special mention" ja Euroopa väärtfilmikinode keti Europa Cinemas preemia. Ka Asko Kase lühifilmi "Zen läbi prügi linastumisest ning teistest auhinnasaajatest ning osalejatest

  14. Delay-independent stabilization for teleoperation with time varying delay

    OpenAIRE

    Fujita, Hiroyuki; Namerikawa, Toru

    2009-01-01

    This paper deals with the stability for nonlinear teleoperation with time varying communication delays. The proposed method is passivity-based controllers with time varying gains which depend on the rate of change of time varying delay. In our proposed method, stability condition is independent of the magnitude of the communication delay and the damping of the system. The delay-independent stability is shown via Lyapunov stability methods. Several experimental results show the effectiveness o...

  15. Harmonic functions with varying coefficients

    Directory of Open Access Journals (Sweden)

    Jacek Dziok

    2016-05-01

    Full Text Available Abstract Complex-valued harmonic functions that are univalent and sense preserving in the open unit disk can be written in the form f = h + g ‾ $f=h+\\overline{g}$ , where h and g are analytic. In this paper we investigate some classes of univalent harmonic functions with varying coefficients related to Janowski functions. By using the extreme points theory we obtain necessary and sufficient convolution conditions, coefficients estimates, distortion theorems, and integral mean inequalities for these classes of functions. The radii of starlikeness and convexity for these classes are also determined.

  16. Linearized Bekenstein Varying Alpha Models

    CERN Document Server

    Pina-Avelino, P; Oliveira, J C

    2004-01-01

    We study the simplest class of Bekenstein-type, varying $\\alpha$ models, in which the two available free functions (potential and gauge kinetic function) are Taylor-expanded up to linear order. Any realistic model of this type reduces to a model in this class for a certain time interval around the present day. Nevertheless, we show that no such model is consistent with all existing observational results. We discuss possible implications of these findings, and in particular clarify the ambiguous statement (often found in the literature) that ``the Webb results are inconsistent with Oklo''.

  17. Linearized Bekenstein varying α models

    Science.gov (United States)

    Avelino, P. P.; Martins, C. J.; Oliveira, J. C.

    2004-10-01

    We study the simplest class of Bekenstein-type, varying α models, in which the two available free functions (potential and gauge kinetic function) are Taylor-expanded up to linear order. Any realistic model of this type reduces to a model in this class for a certain time interval around the present day. Nevertheless, we show that no such model is consistent with all existing observational results. We discuss possible implications of these findings, and, in particular, clarify the ambiguous statement (often found in the literature) that “the Webb results are inconsistent with Oklo.”

  18. Time-varying cosmological term

    Science.gov (United States)

    Socorro, J.; D'oleire, M.; Pimentel, Luis O.

    2015-11-01

    We present the case of time-varying cosmological term using the Lagrangian formalism characterized by a scalar field ϕ with standard kinetic energy and arbitrary potential V(ϕ). This model is applied to Friedmann-Robertson-Walker (FRW)cosmology. Exact solutions of the field equations are obtained by a special ansats to solve the Einstein-Klein-Gordon equation and a particular potential for the scalar field and barotropic perfect fluid. We present the evolution on this cosmological term with different scenarios.

  19. Varying Constants, Gravitation and Cosmology

    Directory of Open Access Journals (Sweden)

    Jean-Philippe Uzan

    2011-03-01

    Full Text Available Fundamental constants are a cornerstone of our physical laws. Any constant varying in space and/or time would reflect the existence of an almost massless field that couples to matter. This will induce a violation of the universality of free fall. Thus, it is of utmost importance for our understanding of gravity and of the domain of validity of general relativity to test for their constancy. We detail the relations between the constants, the tests of the local position invariance and of the universality of free fall. We then review the main experimental and observational constraints that have been obtained from atomic clocks, the Oklo phenomenon, solar system observations, meteorite dating, quasar absorption spectra, stellar physics, pulsar timing, the cosmic microwave background and big bang nucleosynthesis. At each step we describe the basics of each system, its dependence with respect to the constants, the known systematic effects and the most recent constraints that have been obtained. We then describe the main theoretical frameworks in which the low-energy constants may actually be varying and we focus on the unification mechanisms and the relations between the variation of different constants. To finish, we discuss the more speculative possibility of understanding their numerical values and the apparent fine-tuning that they confront us with.

  20. Varying Constants, Gravitation and Cosmology.

    Science.gov (United States)

    Uzan, Jean-Philippe

    2011-01-01

    Fundamental constants are a cornerstone of our physical laws. Any constant varying in space and/or time would reflect the existence of an almost massless field that couples to matter. This will induce a violation of the universality of free fall. Thus, it is of utmost importance for our understanding of gravity and of the domain of validity of general relativity to test for their constancy. We detail the relations between the constants, the tests of the local position invariance and of the universality of free fall. We then review the main experimental and observational constraints that have been obtained from atomic clocks, the Oklo phenomenon, solar system observations, meteorite dating, quasar absorption spectra, stellar physics, pulsar timing, the cosmic microwave background and big bang nucleosynthesis. At each step we describe the basics of each system, its dependence with respect to the constants, the known systematic effects and the most recent constraints that have been obtained. We then describe the main theoretical frameworks in which the low-energy constants may actually be varying and we focus on the unification mechanisms and the relations between the variation of different constants. To finish, we discuss the more speculative possibility of understanding their numerical values and the apparent fine-tuning that they confront us with.

  1. Varying Constants, Gravitation and Cosmology

    Science.gov (United States)

    Uzan, Jean-Philippe

    2011-12-01

    Fundamental constants are a cornerstone of our physical laws. Any constant varying in space and/or time would reflect the existence of an almost massless field that couples to matter. This will induce a violation of the universality of free fall. Thus, it is of utmost importance for our understanding of gravity and of the domain of validity of general relativity to test for their constancy. We detail the relations between the constants, the tests of the local position invariance and of the universality of free fall. We then review the main experimental and observational constraints that have been obtained from atomic clocks, the Oklo phenomenon, solar system observations, meteorite dating, quasar absorption spectra, stellar physics, pulsar timing, the cosmic microwave background and big bang nucleosynthesis. At each step we describe the basics of each system, its dependence with respect to the constants, the known systematic effects and the most recent constraints that have been obtained. We then describe the main theoretical frameworks in which the low-energy constants may actually be varying and we focus on the unification mechanisms and the relations between the variation of different constants. To finish, we discuss the more speculative possibility of understanding their numerical values and the apparent fine-tuning that they confront us with.

  2. Time varying arctic climate change amplification

    Energy Technology Data Exchange (ETDEWEB)

    Chylek, Petr [Los Alamos National Laboratory; Dubey, Manvendra K [Los Alamos National Laboratory; Lesins, Glen [DALLHOUSIE U; Wang, Muyin [NOAA/JISAO

    2009-01-01

    During the past 130 years the global mean surface air temperature has risen by about 0.75 K. Due to feedbacks -- including the snow/ice albedo feedback -- the warming in the Arctic is expected to proceed at a faster rate than the global average. Climate model simulations suggest that this Arctic amplification produces warming that is two to three times larger than the global mean. Understanding the Arctic amplification is essential for projections of future Arctic climate including sea ice extent and melting of the Greenland ice sheet. We use the temperature records from the Arctic stations to show that (a) the Arctic amplification is larger at latitudes above 700 N compared to those within 64-70oN belt, and that, surprisingly; (b) the ratio of the Arctic to global rate of temperature change is not constant but varies on the decadal timescale. This time dependence will affect future projections of climate changes in the Arctic.

  3. Local Varying-Alpha Theories

    CERN Document Server

    Barrow, John D

    2014-01-01

    In a recent paper we demonstrated how the simplest model for varying alpha may be interpreted as the effect of a dielectric material, generalized to be consistent with Lorentz invariance. Unlike normal dielectrics, such a medium cannot change the speed of light, and its dynamics obey a Klein-Gordon equation. This work immediately suggests an extension of the standard theory, even if we require compliance with Lorentz invariance. Instead of a wave equation, the dynamics may satisfy a local algebraic relation involving the permittivity and the properties of the electromagnetic field, in analogy with more conventional dielectric (but still preserving Lorentz invariance). We develop the formalism for such theories and investigate some phenomenological implications. The problem of the divergence of the classical self-energy can be solved, or at least softened, in this framework. Some interesting new cosmological solutions for the very early universe are found, including the possibility of a bounce, inflation and e...

  4. Varying constants, Gravitation and Cosmology

    CERN Document Server

    Uzan, Jean-Philippe

    2010-01-01

    Fundamental constants are a cornerstone of our physical laws. Any constant varying in space and/or time would reflect the existence of an almost massless field that couples to matter. This will induce a violation of the universality of free fall. It is thus of utmost importance for our understanding of gravity and of the domain of validity of general relativity to test for their constancy. We thus detail the relations between the constants, the tests of the local position invariance and of the universality of free fall. We then review the main experimental and observational constraints that have been obtained from atomic clocks, the Oklo phenomenon, Solar system observations, meteorites dating, quasar absorption spectra, stellar physics, pulsar timing, the cosmic microwave background and big bang nucleosynthesis. At each step we describe the basics of each system, its dependence with respect to the constants, the known systematic effects and the most recent constraints that have been obtained. We then describ...

  5. Exploration of Periodically Varying Graphs

    CERN Document Server

    Flocchini, Paola; Santoro, Nicola

    2009-01-01

    We study the computability and complexity of the exploration problem in a class of highly dynamic graphs: periodically varying (PV) graphs, where the edges exist only at some (unknown) times defined by the periodic movements of carriers. These graphs naturally model highly dynamic infrastructure-less networks such as public transports with fixed timetables, low earth orbiting (LEO) satellite systems, security guards' tours, etc. We establish necessary conditions for the problem to be solved. We also derive lower bounds on the amount of time required in general, as well as for the PV graphs defined by restricted classes of carriers movements: simple routes, and circular routes. We then prove that the limitations on computability and complexity we have established are indeed tight. In fact we prove that all necessary conditions are also sufficient and all lower bounds on costs are tight. We do so constructively presenting two worst case optimal solution algorithms, one for anonymous systems, and one for those w...

  6. Time-Varying Fundamental Constants

    Science.gov (United States)

    Olive, Keith

    2003-04-01

    Recent data from quasar absorption systems can be interpreted as arising from a time variation in the fine-structure constant. However, there are numerous cosmological, astro-physical, and terrestrial bounds on any such variation. These includes bounds from Big Bang Nucleosynthesis (from the ^4He abundance), the Oklo reactor (from the resonant neutron capture cross-section of Sm), and from meteoretic lifetimes of heavy radioactive isotopes. The bounds on the variation of the fine-structure constant are significantly strengthened in models where all gauge and Yukawa couplings vary in a dependent manner, as would be expected in unified theories. Models which are consistent with all data are severly challenged when Equivalence Principle constraints are imposed.

  7. Weighted approximation with varying weight

    CERN Document Server

    Totik, Vilmos

    1994-01-01

    A new construction is given for approximating a logarithmic potential by a discrete one. This yields a new approach to approximation with weighted polynomials of the form w"n"(" "= uppercase)P"n"(" "= uppercase). The new technique settles several open problems, and it leads to a simple proof for the strong asymptotics on some L p(uppercase) extremal problems on the real line with exponential weights, which, for the case p=2, are equivalent to power- type asymptotics for the leading coefficients of the corresponding orthogonal polynomials. The method is also modified toyield (in a sense) uniformly good approximation on the whole support. This allows one to deduce strong asymptotics in some L p(uppercase) extremal problems with varying weights. Applications are given, relating to fast decreasing polynomials, asymptotic behavior of orthogonal polynomials and multipoint Pade approximation. The approach is potential-theoretic, but the text is self-contained.

  8. MULTIVARIATE VARYING COEFFICIENT MODEL FOR FUNCTIONAL RESPONSES.

    Science.gov (United States)

    Zhu, Hongtu; Li, Runze; Kong, Linglong

    2012-10-01

    Motivated by recent work studying massive imaging data in the neuroimaging literature, we propose multivariate varying coefficient models (MVCM) for modeling the relation between multiple functional responses and a set of covariates. We develop several statistical inference procedures for MVCM and systematically study their theoretical properties. We first establish the weak convergence of the local linear estimate of coefficient functions, as well as its asymptotic bias and variance, and then we derive asymptotic bias and mean integrated squared error of smoothed individual functions and their uniform convergence rate. We establish the uniform convergence rate of the estimated covariance function of the individual functions and its associated eigenvalue and eigenfunctions. We propose a global test for linear hypotheses of varying coefficient functions, and derive its asymptotic distribution under the null hypothesis. We also propose a simultaneous confidence band for each individual effect curve. We conduct Monte Carlo simulation to examine the finite-sample performance of the proposed procedures. We apply MVCM to investigate the development of white matter diffusivities along the genu tract of the corpus callosum in a clinical study of neurodevelopment.

  9. Mixing properties of ARCH and time-varying ARCH processes

    CERN Document Server

    Fryzlewicz, Piotr; 10.3150/10-BEJ270

    2011-01-01

    There exist very few results on mixing for non-stationary processes. However, mixing is often required in statistical inference for non-stationary processes such as time-varying ARCH (tvARCH) models. In this paper, bounds for the mixing rates of a stochastic process are derived in terms of the conditional densities of the process. These bounds are used to obtain the $\\alpha$, 2-mixing and $\\beta$-mixing rates of the non-stationary time-varying $\\operatorname {ARCH}(p)$ process and $\\operatorname {ARCH}(\\infty)$ process. It is shown that the mixing rate of the time-varying $\\operatorname {ARCH}(p)$ process is geometric, whereas the bound on the mixing rate of the $\\operatorname {ARCH}(\\infty)$ process depends on the rate of decay of the $\\operatorname {ARCH}(\\infty)$ parameters. We note that the methodology given in this paper is applicable to other processes.

  10. Gait phase varies over velocities.

    Science.gov (United States)

    Liu, Yancheng; Lu, Kun; Yan, Songhua; Sun, Ming; Lester, D Kevin; Zhang, Kuan

    2014-02-01

    We sought to characterize the percent (PT) of the phases of a gait cycle (GC) as velocity changes to establish norms for pathological gait characteristics with higher resolution technology. Ninety five healthy subjects (49 males and 46 females with age 34.9 ± 11.8 yrs, body weight 64.0 ± 11.7 kg and BMI 23.5 ± 3.6) were enrolled and walked comfortably on a 10-m walkway at self-selected slower, normal, and faster velocities. Walking was recorded with a high speed camera (250 frames per second) and the eight phases of a GC were determined by examination of individual frames for each subject. The correlation coefficients between the mean PT of the phases of the three velocities gaits and PT defined by previous publications were all greater than 0.99. The correlation coefficient between velocity and PT of gait phases is -0.83 for loading response (LR), -0.75 for mid stance (MSt), and -0.84 for pre-swing (PSw). While the PT of the phases of three velocities from this study are highly correlated with PT described by Dr. Jacquenlin Perry decades ago, actual PT of each phase varied amongst these individuals with the largest coefficient variation of 24.31% for IC with slower velocity. From slower to faster walk, the mean PT of MSt diminished from 35.30% to 25.33%. High resolution recording revealed ambiguity of some gait phase definitions, and these data may benefit GC characterization of normal and pathological gait in clinical practice. The study results indicate that one should consider individual variations and walking velocity when evaluating gaits of subjects using standard gait phase classification.

  11. Modelling tourists arrival using time varying parameter

    Science.gov (United States)

    Suciptawati, P.; Sukarsa, K. G.; Kencana, Eka N.

    2017-06-01

    The importance of tourism and its related sectors to support economic development and poverty reduction in many countries increase researchers’ attentions to study and model tourists’ arrival. This work is aimed to demonstrate time varying parameter (TVP) technique to model the arrival of Korean’s tourists to Bali. The number of Korean tourists whom visiting Bali for period January 2010 to December 2015 were used to model the number of Korean’s tourists to Bali (KOR) as dependent variable. The predictors are the exchange rate of Won to IDR (WON), the inflation rate in Korea (INFKR), and the inflation rate in Indonesia (INFID). Observing tourists visit to Bali tend to fluctuate by their nationality, then the model was built by applying TVP and its parameters were approximated using Kalman Filter algorithm. The results showed all of predictor variables (WON, INFKR, INFID) significantly affect KOR. For in-sample and out-of-sample forecast with ARIMA’s forecasted values for the predictors, TVP model gave mean absolute percentage error (MAPE) as much as 11.24 percent and 12.86 percent, respectively.

  12. Local Rank Inference for Varying Coefficient Models.

    Science.gov (United States)

    Wang, Lan; Kai, Bo; Li, Runze

    2009-12-01

    By allowing the regression coefficients to change with certain covariates, the class of varying coefficient models offers a flexible approach to modeling nonlinearity and interactions between covariates. This paper proposes a novel estimation procedure for the varying coefficient models based on local ranks. The new procedure provides a highly efficient and robust alternative to the local linear least squares method, and can be conveniently implemented using existing R software package. Theoretical analysis and numerical simulations both reveal that the gain of the local rank estimator over the local linear least squares estimator, measured by the asymptotic mean squared error or the asymptotic mean integrated squared error, can be substantial. In the normal error case, the asymptotic relative efficiency for estimating both the coefficient functions and the derivative of the coefficient functions is above 96%; even in the worst case scenarios, the asymptotic relative efficiency has a lower bound 88.96% for estimating the coefficient functions, and a lower bound 89.91% for estimating their derivatives. The new estimator may achieve the nonparametric convergence rate even when the local linear least squares method fails due to infinite random error variance. We establish the large sample theory of the proposed procedure by utilizing results from generalized U-statistics, whose kernel function may depend on the sample size. We also extend a resampling approach, which perturbs the objective function repeatedly, to the generalized U-statistics setting; and demonstrate that it can accurately estimate the asymptotic covariance matrix.

  13. Clinical reasearch of re-operation for postoperative recurrence of chronic dacryocystitis%慢性泪囊炎术后复发再手术的临床研究

    Institute of Scientific and Technical Information of China (English)

    周昆; 刘玥; 周明辉

    2016-01-01

    目的:对比改良型外径路和鼻内镜下泪囊鼻腔吻合术对慢性泪囊炎术后复发患者的疗效。方法术后复发的慢性泪囊炎18例(18眼)随机分成两组;A组行外径路泪囊鼻腔吻合术,B组行鼻内镜下泪囊鼻腔吻合术。术后随访6个月。结果 A组8眼中治愈6眼、好转1眼,无效1眼。总体有效率87.50%;B组10眼中治愈9眼、好转1眼,总体有效率100%。两组差异具有统计学意义(χ2=7.8030,P=0.0019)。结论慢性泪囊炎术后复发患者,鼻内镜下泪囊鼻腔吻合术为更适合的手术方式,术前术后需要眼科及耳鼻喉科医师的跨学科合作。%Objective To compare the effect of improved exterior route dacryocystorhinostomy and nasal endoscopic dacryocystorhinostomy for postoperatively recurrent chronic dacryocystitis .Methods Eighteen eyes of 18 cases with postoperative recurrence of chronic dacryocystitis were randomly divided into two groups.8 eyes of group A was treated with improved dacryocystorhinostomy , and 10 eyes of group B was treated with improved nasal endoscopic dacryocystorhinostomy .All patients were followed up for 6 months. Results In group A, 6 eyes were cured, 1 eyes was improved and 1 eye was noneffective; the total therapeutic effective rate was 87.5%.In group B, 9 eyes were cured, 1 eyes was improved and none was noneffective;the total treatment effective rate was 100%.The difference between two groups was statistically significant(χ2 =7.8030,P=0.0019).Conclusion Nasal endoscopic dacryocystorhinostomy is suitable for postoperative recurrence chronic dacryocystitis .Interdisciplinary cooperation between ophthalmologist and rhinologist is required .

  14. Extending satisficing control strategy to slowly varying nonlinear systems

    Science.gov (United States)

    Binazadeh, T.; Shafiei, M. H.

    2013-04-01

    Based on the satisficing control strategy, a novel approach to design a stabilizing control law for nonlinear time varying systems with slowly varying parameters (slowly varying systems) is presented. The satisficing control strategy has been originally introduced for time-invariant systems; however, this technique does not have any stability proof for time varying systems. In this paper, first, a parametric version of the satisficing control strategy is developed. Then, by considering the time as a frozen parameter, the parametric satisficing control strategy is utilized. Finally, a theorem is presented which suggested a stabilizing satisficing control law for the slowly varying control systems. Moreover, in this theorem, the maximum admissible rate of change of the system dynamics is evaluated. The efficiency of the proposed approach is demonstrated by a computer simulation.

  15. Time varying voltage combustion control and diagnostics sensor

    Science.gov (United States)

    Chorpening, Benjamin T.; Thornton, Jimmy D.; Huckaby, E. David; Fincham, William

    2011-04-19

    A time-varying voltage is applied to an electrode, or a pair of electrodes, of a sensor installed in a fuel nozzle disposed adjacent the combustion zone of a continuous combustion system, such as of the gas turbine engine type. The time-varying voltage induces a time-varying current in the flame which is measured and used to determine flame capacitance using AC electrical circuit analysis. Flame capacitance is used to accurately determine the position of the flame from the sensor and the fuel/air ratio. The fuel and/or air flow rate (s) is/are then adjusted to provide reduced flame instability problems such as flashback, combustion dynamics and lean blowout, as well as reduced emissions. The time-varying voltage may be an alternating voltage and the time-varying current may be an alternating current.

  16. Hydrodynamic solutions of spatially-varying 1D exclusion processes

    Science.gov (United States)

    Lakatos, Greg; Chou, Tom

    2007-03-01

    We analyze the open boundary partially asymmetric exclusion process with smoothly varying internal hopping rates in the infinite-size, mean field limit. The mean field equations for particle densities are written in terms of Ricatti equations with the steady-state current J as a parameter. These equations are solved both analytically and numerically. Upon imposing the boundary conditions set by the injection and extraction rates, the currents J are found self-consistently. We find a number of cases where analytic solutions can be found exactly or approximated. Results for J from asymptotic analyses for slowly varying hopping rates agree extremely well with those from extensive Monte Carlo simulations, suggesting that mean field currents are exact as long as the hopping rates vary slowly over the lattice. If the forward hopping rate is greater than or less than the backward hopping rate throughout the entire chain, the three standard steady-state phases are preserved. Our analysis reveals the sensitivity of the current to the relative phase between the forward and backward hopping rate functions.

  17. The Arbitrarily Varying Multiple-Access Channel with Conferencing Encoders

    CERN Document Server

    Wiese, Moritz

    2011-01-01

    We derive the capacity region of arbitrarily varying multiple-access channels with conferencing encoders for both deterministic and random coding. We obtain a dichotomy: either the channel's deterministic capacity region is zero or it equals the two-dimensional random coding region. We determine exactly when either case holds. We also discuss the benefits of conferencing. For both the compound and the arbitrarily varying cases, we give the example of a channel which does not achieve any non-zero rate pair without encoder cooperation, but the two-dimensional random coding capacity region if conferencing is possible. Unlike compound multiple-access channels, arbitrarily varying multiple-access channels may exhibit a discontinuous increase of the capacity region when conferencing is enabled. We use the arbitrarily varying multiple-access channel with conferencing encoders for an information-theoretic analysis of the performance of wireless networks with cooperating base stations disturbed by exterior interferenc...

  18. GPU Generation of Large Varied Animated Crowds

    OpenAIRE

    Isaac Rudomin; Benjamín Hernández; Oriam de Gyves; Leonel Toledo; Ivan Rivalcoba; Sergio Ruiz

    2013-01-01

    ..We discuss several steps in the process of simulating and visualizing large and varied crowds in real time for consumer-level computers and graphic cards (GPUs). Animating varied crowds using a diversity of models and animations (assets) is complex and costly. One has to use models that are expensive if bought, take a long time to model, and consume too much memory and computing resources. We discuss methods for simulating, generating, animating and rendering crowds of varied aspect and a d...

  19. A new varied-time photonic crystals

    OpenAIRE

    Wu, Xiang-Yao; Ma, Ji; Liu, Xiao-Jing; Liang, Yu; Li, Hong; Chen, Wan-Jin; Yuan, Hong-chun; Li, Heng-Mei

    2015-01-01

    In this paper, we have firstly proposed a new one-dimensional varied-time photonic crystals, i.e., the refractive indices of media $A$ and $B$ are the time functions. We consider the varied-time photonic crystals of refractive indices period variation and calculate the transmissivity and electronic field distribution with and without defect layer, which are different from the conventional photonic crystals, which transmissivity and electronic field distribution are static, but the varied-time...

  20. Inflationary Phase with Time Varying Fundamental Constants

    CERN Document Server

    Berman, M S; Berman, Marcelo S.; Trevisan, Luis A.

    2002-01-01

    Following Barrow, and Barrow and collaborators, we find a cosmological JBD model, with varying speed of light and varying fine structure constant, where the deceleration parameter is -1,causing acceleration of the Universe.Indeed, we have an exponential inflationary phase. Plancks time, energy, length,etc.,might have had different numerical values in the past, than those available in the litterature, due to the varying values for speed of light, and gravitational constant.

  1. A new varied-time photonic crystals

    OpenAIRE

    2015-01-01

    In this paper, we have firstly proposed a new one-dimensional varied-time photonic crystals, i.e., the refractive indices of media $A$ and $B$ are the time functions. We consider the varied-time photonic crystals of refractive indices period variation and calculate the transmissivity and electronic field distribution with and without defect layer, which are different from the conventional photonic crystals, which transmissivity and electronic field distribution are static, but the varied-time...

  2. Time varying effects in survival analysis

    DEFF Research Database (Denmark)

    Scheike, Thomas H.

    2002-01-01

    additive risk model; counting process; proportional hazards model; semi-parametric models; survival data; time-varying effects; nonparametric testing......additive risk model; counting process; proportional hazards model; semi-parametric models; survival data; time-varying effects; nonparametric testing...

  3. Fractal analysis of time varying data

    Science.gov (United States)

    Vo-Dinh, Tuan; Sadana, Ajit

    2002-01-01

    Characteristics of time varying data, such as an electrical signal, are analyzed by converting the data from a temporal domain into a spatial domain pattern. Fractal analysis is performed on the spatial domain pattern, thereby producing a fractal dimension D.sub.F. The fractal dimension indicates the regularity of the time varying data.

  4. Varying Alpha and the Electroweak Model

    CERN Document Server

    Kimberly, D; Kimberly, Dagny; Magueijo, Joao

    2003-01-01

    Inspired by recent claims for a varying fine structure constant, alpha, we investigate the effect of ``promoting coupling constants to variables'' upon various parameters of the standard model. We first consider a toy model: Proca's theory of the massive photon. We then explore the electroweak theory with one and two dilaton fields. We find that a varying alpha unavoidably implies varying W and Z masses. This follows from gauge invariance, and is to be contrasted with Proca' theory. For the two dilaton theory the Weinberg angle is also variable, but Fermi's constant and the tree level fermion masses remain constant unless the Higgs' potential becomes dynamical. We outline some cosmological implications.

  5. Influência de variáveis químicas e estruturais do dossel sobre a taxa de ingestão instantânea em bovinos manejados em pastagens tropicais Influence of structural characteristics and chemical composition of tropical grasses on the instantaneous forage intake rate

    Directory of Open Access Journals (Sweden)

    Fabíola Cristine de Almeida Rego

    2006-06-01

    Full Text Available Avaliou-se a taxa de ingestão (TI em bovinos em pastagens exclusivas de Brachiaria brizantha, Panicum maximum cv. Tanzânia, Arachis pintoi e uma consorciação de Brachiaria brizantha com Arachis pintoi com o objetivo de selecionar as características estruturais e qualitativas da planta, de maior importância para estimativa da taxa de ingestão dos animais. Os animais pastejavam em pares, passando por todas as alturas e espécies em dias sucessivos. Após jejum de três horas, permaneciam por 60 minutos na área experimental, onde foram quantificados o tempo efetivo de pastejo e o número de bocados. A quantidade de forragem ingerida foi estimada pela técnica de dupla pesagem. As características estruturais da pastagem utilizadas na equação para determinar a TI foram altura média da pastagem (cm, proporção dos componentes morfológicos (%, massa dos componentes morfológicos (t MS/ha e densidade de matéria seca dos componentes morfológicos (kg MS/ha/cm. As características qualitativas foram expressas em termos de PB e de FDN. As variáveis da pastagem foram selecionadas pelo procedimento estatístico stepwise. As equações das TI, definidas a partir das características estudadas, foram: capim-marandu: TI = 59,8980 + 0,7299 LV + 3,5777 MF - 1,2459 FDNL + 0,2882 ALT (LV - proporção de lâminas verdes, MF - massa de forragem, FDNL - FDN de lâminas, ALT - altura média da pastagem. Capim-tanzânia: TI = 111,762 - 4,1532 PBL + 0,3469 LV - 0,5207 FDNL (PB de lâminas, LV - proporção de lâminas verdes, FDNL - FDN de lâminas. Amendoim forrageiro: TI = -196,589 + 12,1978 PBH + 8,3406 MF + 1,1060 HV + 17,3669 MLV (PBH - PB de HASTEs, MF - massa de forragem, DLV - massa de lâminas verdes. Consorciação: TI = -7,25 + 1,15ALTA - 0,22ALTI + 18,49MA - 9,88MLM + 0,49ALTM + 1,00PBL (ALTA - altura amendoim forrageiro, ALTI - altura de invasoras, MA - massa de amendoim forrageiro, MLM - massa de lâminas verdes de capim-marandu, ALTM

  6. Tavatult jahe Karlovy Vary / Jaanus Noormets

    Index Scriptorium Estoniae

    Noormets, Jaanus

    2011-01-01

    1.-10. juulini toimunud Karlovy Vary 46. filmifestivalist (muusikafilmide alajaotuses näidati Marianne Kõrveri dokumentaalfilmi "Erkki-Sven Tüür: 7 etüüdi piltides" (2010) programmis "A Musical Odyssey")

  7. Inhomogeneous Universe Models with Varying Cosmological Term

    CERN Document Server

    Chimento, L P; Chimento, Luis P.; Pavon, Diego

    1998-01-01

    The evolution of a class of inhomogeneous spherically symmetric universe models possessing a varying cosmological term and a material fluid, with an adiabatic index either constant or not, is studied.

  8. Social contagions on time-varying community networks

    CERN Document Server

    Liu, Mian-Xin; Liu, Ying; Tang, Ming; Cai, Shi-Min; Zhang, Hai-Feng

    2016-01-01

    Time-varying community structures widely exist in various real-world networks. However, the spreading dynamics on this kind of network has not been fully studied. To this end, we systematically study the effects of time-varying community structures on social contagions. We first propose a non-Markovian social contagion model on time-varying community networks based on the activity driven network model, in which an individual adopts a behavior if and only if the accumulated behavioral information it has ever received reaches a threshold. Then, we develop a mean-field theory to describe the proposed model. From theoretical analyses and numerical simulations, we find that behavior adoption in the social contagions exhibits a hierarchical feature, i.e., the behavior first quickly spreads in one of the communities, and then outbreaks in the other. Moreover, under different behavioral information transmission rates, the final behavior adoption proportion in the whole network versus the community strength shows one ...

  9. Method and apparatus of prefetching streams of varying prefetch depth

    Science.gov (United States)

    Gara, Alan [Mount Kisco, NY; Ohmacht, Martin [Yorktown Heights, NY; Salapura, Valentina [Chappaqua, NY; Sugavanam, Krishnan [Mahopac, NY; Hoenicke, Dirk [Seebruck-Seeon, DE

    2012-01-24

    Method and apparatus of prefetching streams of varying prefetch depth dynamically changes the depth of prefetching so that the number of multiple streams as well as the hit rate of a single stream are optimized. The method and apparatus in one aspect monitor a plurality of load requests from a processing unit for data in a prefetch buffer, determine an access pattern associated with the plurality of load requests and adjust a prefetch depth according to the access pattern.

  10. PERFORMANCE EVALUATION OF DWTBASED MULTICARRIER SYSTEM IN TIME VARYING CHANNELS

    OpenAIRE

    Meenu S Kumar; Sandra Prasad; Ramanathan R

    2015-01-01

    With an increase in user mobility, data rate and carrier frequencies we have to consider time variant channels. In order to overcome the impairments of the time varying channel on conventional OFDM system, a wavelet based OFDM system is investigated in place of FFT based system and its BER performance is analyzed for different Doppler frequencies. The results show that DWT based OFDM gives better performance compared to conventional OFDM system.

  11. PERFORMANCE EVALUATION OF DWTBASED MULTICARRIER SYSTEM IN TIME VARYING CHANNELS

    Directory of Open Access Journals (Sweden)

    Meenu S Kumar

    2015-10-01

    Full Text Available With an increase in user mobility, data rate and carrier frequencies we have to consider time variant channels. In order to overcome the impairments of the time varying channel on conventional OFDM system, a wavelet based OFDM system is investigated in place of FFT based system and its BER performance is analyzed for different Doppler frequencies. The results show that DWT based OFDM gives better performance compared to conventional OFDM system.

  12. Digital repetitive control under varying frequency conditions

    CERN Document Server

    Ramos, Germán A; Olm, Josep M

    2013-01-01

    The tracking/rejection of periodic signals constitutes a wide field of research in the control theory and applications area. Repetitive Control has proven to be an efficient way to face this topic. However, in some applications the frequency of the reference/disturbance signal is time-varying or uncertain. This causes an important performance degradation in the standard Repetitive Control scheme. This book presents some solutions to apply Repetitive Control in varying frequency conditions without loosing steady-state performance. It also includes a complete theoretical development and experimental results in two representative systems. The presented solutions are organized in two complementary branches: varying sampling period Repetitive Control and High Order Repetitive Control. The first approach allows dealing with large range frequency variations while the second allows dealing with small range frequency variations. The book also presents applications of the described techniques to a Roto-magnet plant and...

  13. Varying alpha and the electroweak model

    Energy Technology Data Exchange (ETDEWEB)

    Kimberly, Dagny; Magueijo, Joao

    2004-03-25

    Inspired by recent claims for a varying fine structure constant, alpha, we investigate the effect of 'promoting coupling constants to variables' upon various parameters of the standard model. We first consider a toy model: Proca theory of the massive photon. We then explore the electroweak theory with one and two dilaton fields. We find that a varying alpha unavoidably implies varying W and Z masses. This follows from gauge invariance, and is to be contrasted with Proca theory. For the two dilaton theory the Weinberg angle is also variable, but Fermi's constant and the tree level fermion masses remain constant unless the Higgs potential becomes dynamical. We outline some cosmological implications.

  14. Solar mass-varying neutrino oscillations.

    Science.gov (United States)

    Barger, V; Huber, Patrick; Marfatia, Danny

    2005-11-18

    We propose that the solar neutrino deficit may be due to oscillations of mass-varying neutrinos (MaVaNs). This scenario elucidates solar neutrino data beautifully while remaining comfortably compatible with atmospheric neutrino and K2K data and with reactor antineutrino data at short and long baselines (from CHOOZ and KamLAND). We find that the survival probability of solar MaVaNs is independent of how the suppression of neutrino mass caused by the acceleron-matter couplings varies with density. Measurements of MeV and lower energy solar neutrinos will provide a rigorous test of the idea.

  15. Filmihullu eluvesi voolab Karlovy Varys / Margit Tõnson

    Index Scriptorium Estoniae

    Tõnson, Margit, 1978-

    2010-01-01

    Karlovy Vary rahvusvahelisest filmifestivalist. Filmidest "Mr. Nobody" (rež. Jaco Van Dormaeli), "Kasside ema Teresa" (rež. Pawel Sala) ja "The Arbor" (rež. Clio Barnardi). Nimekiri võitnud töödest ja viimastel aastatel festivalil näidatud Eesti mängufilmidest

  16. Efficient Estimation in Heteroscedastic Varying Coefficient Models

    Directory of Open Access Journals (Sweden)

    Chuanhua Wei

    2015-07-01

    Full Text Available This paper considers statistical inference for the heteroscedastic varying coefficient model. We propose an efficient estimator for coefficient functions that is more efficient than the conventional local-linear estimator. We establish asymptotic normality for the proposed estimator and conduct some simulation to illustrate the performance of the proposed method.

  17. Cosmo MSW effect for mass varying neutrinos

    CERN Document Server

    Hung, P Q; Hung, Pham Quang; P\\"as, Heinrich

    2003-01-01

    We consider neutrinos with varying masses which arise in scenarios relating neutrino masses to the dark energy density in the universe. We point out that the neutrino mass variation can lead to level crossing and thus a cosmo MSW effect, having dramatic consequences for the flavor ratio of astrophysical neutrinos and the composition of the relic neutrino background.

  18. Õunpuu Karlovy Varys edukas

    Index Scriptorium Estoniae

    2010-01-01

    45. Karlovy Vary filmifestivali võistlusprogrammis "East of the West" märgiti ära Veiko Õunpuu film "Püha Tõnu kiusamine". Peaauhind läks rumeenlase Cristi Puiu filmile "Aurora". Grand prix´sai Augustĺ Vila film "La mosquitera". Teisi preemiasaajaid

  19. Filmihullu eluvesi voolab Karlovy Varys / Margit Tõnson

    Index Scriptorium Estoniae

    Tõnson, Margit, 1978-

    2010-01-01

    Karlovy Vary rahvusvahelisest filmifestivalist. Filmidest "Mr. Nobody" (rež. Jaco Van Dormaeli), "Kasside ema Teresa" (rež. Pawel Sala) ja "The Arbor" (rež. Clio Barnardi). Nimekiri võitnud töödest ja viimastel aastatel festivalil näidatud Eesti mängufilmidest

  20. Ellipsometry with randomly varying polarization states

    NARCIS (Netherlands)

    Liu, F.; Lee, C. J.; Chen, J. Q.; E. Louis,; van der Slot, P. J. M.; Boller, K. J.; F. Bijkerk,

    2012-01-01

    We show that, under the right conditions, one can make highly accurate polarization-based measurements without knowing the absolute polarization state of the probing light field. It is shown that light, passed through a randomly varying birefringent material has a well-defined orbit on the Poincar s

  1. Risk Value (VaR)Measurement of Overnight Rate of Commercial Banks in China---Based on Time -varying Volatility Method%我国商业银行隔夜拆借利率风险值(VaR)度量--基于时变波动率方法的研究

    Institute of Scientific and Technical Information of China (English)

    宿玉海; 王美伶

    2015-01-01

    By comparing the GARCH and TARCH model,the paper selects the better one and measures the interest rate risk of the commercial banks based on the method of VaR.The empirical analysis shows that the interest rate risk of the commercial banks is in-creasing with the deepening of privatization of interest rate and the impact of interest rate on the commercial banks has the characteristic of asymmetry.And then the paper puts forward the policy suggestions according to the empirical result.%通过 GARCH 模型和 TARCH 模型的对比选择最优模型,在使用 VaR 方法的基础上对我国商业银行所面临的利率风险进行度量,得出在利率市场化背景下我国商业银行所面临的利率风险有增无减,而且利率对于商业银行的冲击存在非对称性的实证结果,并根据实证结果提出了相应的政策建议。

  2. Varying-coefficient functional linear regression

    CERN Document Server

    Wu, Yichao; Müller, Hans-Georg; 10.3150/09-BEJ231

    2011-01-01

    Functional linear regression analysis aims to model regression relations which include a functional predictor. The analog of the regression parameter vector or matrix in conventional multivariate or multiple-response linear regression models is a regression parameter function in one or two arguments. If, in addition, one has scalar predictors, as is often the case in applications to longitudinal studies, the question arises how to incorporate these into a functional regression model. We study a varying-coefficient approach where the scalar covariates are modeled as additional arguments of the regression parameter function. This extension of the functional linear regression model is analogous to the extension of conventional linear regression models to varying-coefficient models and shares its advantages, such as increased flexibility; however, the details of this extension are more challenging in the functional case. Our methodology combines smoothing methods with regularization by truncation at a finite numb...

  3. Varying flexibilities in systems of organised decentralisation

    DEFF Research Database (Denmark)

    Ilsøe, Anna; Andersen, Søren Kaj

    information, collective agreements and interviews with representatives from tradeunions and employers' associations in Germany and Denmark. Based on our preliminary findings three explanatory theses for further research are developed in the article: 1) The level of specification, i.e. the level where...... response to this pressure from the company level can be described as a form of organised decentralisation in both countries, the response within the Danish collective bargaining system can be characterised as a proactive organised decentralisation while the response of the German system should rather...... be while the response of the German system should rather be interpreted as a reactive organised decentralisation. 3) The varying regulation of working time flexibility in Germany and Denmark implies varying risks in the regulation. In Germany lacking competencies in small or medium-sized companies lead...

  4. Varying flexibilities in systems of organised decentralisation

    DEFF Research Database (Denmark)

    Ilsøe, Anna; Andersen, Søren Kaj

    information, collective agreements and interviews with representatives from tradeunions and employers' associations in Germany and Denmark. Based on our preliminary findings three explanatory theses for further research are developed in the article: 1) The level of specification, i.e. the level where...... response to this pressure from the company level can be described as a form of organised decentralisation in both countries, the response within the Danish collective bargaining system can be characterised as a proactive organised decentralisation while the response of the German system should rather...... be while the response of the German system should rather be interpreted as a reactive organised decentralisation. 3) The varying regulation of working time flexibility in Germany and Denmark implies varying risks in the regulation. In Germany lacking competencies in small or medium-sized companies lead...

  5. Brain size varies with temperature in vertebrates

    OpenAIRE

    2014-01-01

    The tremendous variation in brain size among vertebrates has long been thought to be related to differences in species’ metabolic rates. It is thought that species with higher metabolic rates can supply more energy to support the relatively high cost of brain tissue. And yet, while body temperature is known to be a major determinant of metabolic rate, the possible effects of temperature on brain size have scarcely been explored. Thus, here we explore the effects of temperature on brain size a...

  6. On a time varying fine structure constant

    CERN Document Server

    Berman, M S; Berman, Marcelo S.; Trevisan, Luis A.

    2001-01-01

    By employing Dirac LNH, and a further generalization by Berman (GLNH), we estimate how should vary the total number of nucleons, the energy density, Newton Gravitational constant, the cosmological constant, the magnetic permeability and electric permitivity, of the Universe,in order to account for the experimentally observed time variation of the fine structure constant. As a bonus,we find an acceptable value for the deceleration parameter of the present Universe, compatible with the Supernovae observations.

  7. New varying speed of light theories

    CERN Document Server

    Magueijo, J

    2003-01-01

    We review recent work on the possibility of a varying speed of light (VSL). We start by discussing the physical meaning of a varying $c$, dispelling the myth that the constancy of $c$ is a matter of logical consistency. We then summarize the main VSL mechanisms proposed so far: hard breaking of Lorentz invariance; bimetric theories (where the speeds of gravity and light are not the same); locally Lorentz invariant VSL theories; theories exhibiting a color dependent speed of light; varying $c$ induced by extra dimensions (e.g. in the brane-world scenario); and field theories where VSL results from vacuum polarization or CPT violation. We show how VSL scenarios may solve the cosmological problems usually tackled by inflation, and also how they may produce a scale-invariant spectrum of Gaussian fluctuations, capable of explaining the WMAP data. We then review the connection between VSL and theories of quantum gravity, showing how ``doubly special'' relativity has emerged as a VSL effective model of quantum space...

  8. Fault detection in reciprocating compressor valves under varying load conditions

    Science.gov (United States)

    Pichler, Kurt; Lughofer, Edwin; Pichler, Markus; Buchegger, Thomas; Klement, Erich Peter; Huschenbett, Matthias

    2016-03-01

    This paper presents a novel approach for detecting cracked or broken reciprocating compressor valves under varying load conditions. The main idea is that the time frequency representation of vibration measurement data will show typical patterns depending on the fault state. The problem is to detect these patterns reliably. For the detection task, we make a detour via the two dimensional autocorrelation. The autocorrelation emphasizes the patterns and reduces noise effects. This makes it easier to define appropriate features. After feature extraction, classification is done using logistic regression and support vector machines. The method's performance is validated by analyzing real world measurement data. The results will show a very high detection accuracy while keeping the false alarm rates at a very low level for different compressor loads, thus achieving a load-independent method. The proposed approach is, to our best knowledge, the first automated method for reciprocating compressor valve fault detection that can handle varying load conditions.

  9. New varying speed of light theories

    Energy Technology Data Exchange (ETDEWEB)

    Magueijo, Joao [Blackett Laboratory, Imperial College of Science, Technology and Medicine, South Kensington, London SW7 2BZ (United Kingdom)

    2003-11-01

    We review recent work on the possibility of a varying speed of light (VSL). We start by discussing the physical meaning of a varying-c, dispelling the myth that the constancy of c is a matter of logical consistency. We then summarize the main VSL mechanisms proposed so far: hard breaking of Lorentz invariance; bimetric theories (where the speeds of gravity and light are not the same); locally Lorentz invariant VSL theories; theories exhibiting a colour-dependent speed of light; varying-c induced by extra dimensions (e.g. in the brane-world scenario); and field theories where VSL results from vacuum polarization or CPT violation. We show how VSL scenarios may solve the cosmological problems usually tackled by inflation, and also how they may produce a scale-invariant spectrum of Gaussian fluctuations, capable of explaining the WMAP data. We then review the connection between VSL and theories of quantum gravity, showing how 'doubly special' relativity has emerged as a VSL effective model of quantum space-time, with observational implications for ultra-high energy cosmic rays (UHECRs) and gamma ray bursts. Some recent work on the physics of 'black' holes and other compact objects in VSL theories is also described, highlighting phenomena associated with spatial (as opposed to temporal) variations in c. Finally, we describe the observational status of the theory. The evidence is currently slim-redshift dependence in the atomic fine structure, anomalies with UHECRs, and (to a much lesser extent) the acceleration of the universe and the WMAP data. The constraints (e.g. those arising from nucleosynthesis or geological bounds) are tight but not insurmountable. We conclude with the observational predictions of the theory and the prospects for its refutation or vindication.

  10. New varying speed of light theories

    Science.gov (United States)

    Magueijo, João

    2003-11-01

    We review recent work on the possibility of a varying speed of light (VSL). We start by discussing the physical meaning of a varying-c, dispelling the myth that the constancy of c is a matter of logical consistency. We then summarize the main VSL mechanisms proposed so far: hard breaking of Lorentz invariance; bimetric theories (where the speeds of gravity and light are not the same); locally Lorentz invariant VSL theories; theories exhibiting a colour-dependent speed of light; varying-c induced by extra dimensions (e.g. in the brane-world scenario); and field theories where VSL results from vacuum polarization or CPT violation. We show how VSL scenarios may solve the cosmological problems usually tackled by inflation, and also how they may produce a scale-invariant spectrum of Gaussian fluctuations, capable of explaining the WMAP data. We then review the connection between VSL and theories of quantum gravity, showing how 'doubly special' relativity has emerged as a VSL effective model of quantum space-time, with observational implications for ultra-high energy cosmic rays (UHECRs) and gamma ray bursts. Some recent work on the physics of 'black' holes and other compact objects in VSL theories is also described, highlighting phenomena associated with spatial (as opposed to temporal) variations in c. Finally, we describe the observational status of the theory. The evidence is currently slim—redshift dependence in the atomic fine structure, anomalies with UHECRs, and (to a much lesser extent) the acceleration of the universe and the WMAP data. The constraints (e.g. those arising from nucleosynthesis or geological bounds) are tight but not insurmountable. We conclude with the observational predictions of the theory and the prospects for its refutation or vindication.

  11. Tracking time-varying coefficient-functions

    DEFF Research Database (Denmark)

    Nielsen, Henrik Aalborg; Nielsen, Torben Skov; Joensen, Alfred K.;

    2000-01-01

    is a combination of recursive least squares with exponential forgetting and local polynomial regression. It is argued, that it is appropriate to let the forgetting factor vary with the value of the external signal which is the argument of the coefficient functions. Some of the key properties of the modified method......, but otherwise unknown, functions of a low-dimensional input process. These coefficient functions are estimated adaptively and recursively without specifying a global parametric, form, i.e. the method allows for online tracking of the coefficient functions. Essentially, in its most simple form, the method...

  12. Tracking Time-Varying Coefficient-Functions

    DEFF Research Database (Denmark)

    Nielsen, Henrik Aalborg; Nielsen, Torben Skov; Joensen, Alfred K.;

    1999-01-01

    of recursive least squares with exponential forgetting and local polynomial regression. However, it is argued, that it is appropriate to let the forgetting factor vary with the value of the external signal shich is argument of the coeffieient-functions.The properties of the modified method are sutdied......A conditional parametric ARX-model is an ARX-model in which the parameters re replaced by smooth functions of an, possibly multivariate, externalinput signal. These functions are called coefficient functions is suggested. Essentially, in its most simple form, this method is a combination...

  13. A time-varying magnetic flux concentrator

    Science.gov (United States)

    Kibret, B.; Premaratne, M.; Lewis, P. M.; Thomson, R.; Fitzgerald, P. B.

    2016-08-01

    It is known that diverse technological applications require the use of focused magnetic fields. This has driven the quest for controlling the magnetic field. Recently, the principles in transformation optics and metamaterials have allowed the realization of practical static magnetic flux concentrators. Extending such progress, here, we propose a time-varying magnetic flux concentrator cylindrical shell that uses electric conductors and ferromagnetic materials to guide magnetic flux to its center. Its performance is discussed based on finite-element simulation results. Our proposed design has potential applications in magnetic sensors, medical devices, wireless power transfer, and near-field wireless communications.

  14. Image Based Rendering under Varying Illumination

    Institute of Scientific and Technical Information of China (English)

    Wang Chengfeng (王城峰); Hu Zhanyi

    2003-01-01

    A new approach for photorealistic rendering of a class of objects at arbitrary illumination is presented. The approach of the authors relies entirely on image based rendering techniques. A scheme is utilized for re-illumination of objects based on linear combination of low dimensional image representations. The minimum rendering condition of technique of the authors is three sample images under varying illumination of a reference object and a single input image of an interested object. Important properties of this approach are its simplicity, robustness and speediness. Experimental results validate the proposed rendering approach.

  15. A von Bertalanffy growth model with a seasonally varying coefficient

    Science.gov (United States)

    Cloern, James E.; Nichols, Frederic H.

    1978-01-01

    The von Bertalanffy model of body growth is inappropriate for organisms whose growth is restricted to a seasonal period because it assumes that growth rate is invariant with time. Incorporation of a time-varying coefficient significantly improves the capability of the von Bertalanffy equation to describe changing body size of both the bivalve mollusc Macoma balthicain San Francisco Bay and the flathead sole, Hippoglossoides elassodon, in Washington state. This simple modification of the von Bertalanffy model should offer improved predictions of body growth for a variety of other aquatic animals.

  16. Seasonally Varying Reference Atmospheres for East Asia

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Vertical profiles of seasonally varying pressure, temperature, water vapor, and trace gases (O3, N2O, CO,CH4), representing atmospheric conditions up to a height of 100 km over the East Asia region (30°-50°N,110°-150°E) were constructed by using various observation data, model outputs of atmospheric thermodynamic parameters, and gaseous concentrations. Optical characteristics of the obtained East Asia reference atmospheres were compared with those from typical midlatitude summer and winter atmospheres. It was noted that, in the water vapor field, there are major differences between the two model atmospheres during the summer. The resultant impact during the summer of water vapor difference on incoming solar fluxes at the surface and emitted terrestrial fluxes at the top of the atmosphere are 14.3 W m-2 and 6.5 W m-2,respectively. On the other hand, the winter difference between East Asian and midlatitude atmospheres appears to be insignificant. Reference atmospheres for the spring and fall are also available. Utilizing the constructed atmospheric profiles as inputs to the radiative transfer model, it is expected that the constructed seasonally varying reference atmospheres can facilitate better descriptions of optical properties in East Asia.

  17. Varying prior information in Bayesian inversion

    Science.gov (United States)

    Walker, Matthew; Curtis, Andrew

    2014-06-01

    Bayes' rule is used to combine likelihood and prior probability distributions. The former represents knowledge derived from new data, the latter represents pre-existing knowledge; the Bayesian combination is the so-called posterior distribution, representing the resultant new state of knowledge. While varying the likelihood due to differing data observations is common, there are also situations where the prior distribution must be changed or replaced repeatedly. For example, in mixture density neural network (MDN) inversion, using current methods the neural network employed for inversion needs to be retrained every time prior information changes. We develop a method of prior replacement to vary the prior without re-training the network. Thus the efficiency of MDN inversions can be increased, typically by orders of magnitude when applied to geophysical problems. We demonstrate this for the inversion of seismic attributes in a synthetic subsurface geological reservoir model. We also present results which suggest that prior replacement can be used to control the statistical properties (such as variance) of the final estimate of the posterior in more general (e.g., Monte Carlo based) inverse problem solutions.

  18. Estimation of time-varying selectivity in stock assessments using state-space models

    DEFF Research Database (Denmark)

    Nielsen, Anders; Berg, Casper Willestofte

    2014-01-01

    -varying selectivity pattern. The fishing mortality rates are considered (possibly correlated) stochastic processes, and the corresponding process variances are estimated within the model. The model is applied to North Sea cod and it is verified from simulations that time-varying selectivity can be estimated...

  19. Inventory Replenishment Policy with Time-Varying Demand and Shortages Considering Time-Varying Costs

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper, a generalized EOQ model is developed with time-varying demand and shortages considering time-varying costs. The solution procedure is shown for determining the op timal replenishment policy over a finite time horizon during which the replenishment periods are assumed to be constant. The existence and uniqueness of the optimal replenishment policy are pre sented. The procedure is illustrated with two special cases of linear and non-linear demands and costs. Two numerical examples are also given.

  20. Psycho-Physical Effects of Varied Rest Intervals Following Warm-Up

    Science.gov (United States)

    Aronchick, Joel; Burke, Edmund J.

    1977-01-01

    An assessment of the effects of rest intervals of varying lengths following a five minute warm-up revealed no significant differeence among them for perceived exertion, heart rate, and state anxiety. (MB)

  1. Epidemic spreading in time-varying community networks

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Guangming, E-mail: wangxy@dlut.edu.cn, E-mail: ren-guang-ming@163.com [School of Electronic and Information, Guangdong Polytechnic Normal University, Guangzhou 510665 (China); Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024 (China); Wang, Xingyuan, E-mail: wangxy@dlut.edu.cn, E-mail: ren-guang-ming@163.com [Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024 (China)

    2014-06-15

    The spreading processes of many infectious diseases have comparable time scale as the network evolution. Here, we present a simple networks model with time-varying community structure, and investigate susceptible-infected-susceptible epidemic spreading processes in this model. By both theoretic analysis and numerical simulations, we show that the efficiency of epidemic spreading in this model depends intensively on the mobility rate q of the individuals among communities. We also find that there exists a mobility rate threshold q{sub c}. The epidemic will survive when q > q{sub c} and die when q < q{sub c}. These results can help understanding the impacts of human travel on the epidemic spreading in complex networks with community structure.

  2. Toluene metabolism during exposure to varying concentrations combined with exercise

    DEFF Research Database (Denmark)

    Bælum, Jesper; Døssing, M; Hansen, S H

    1987-01-01

    between the exposure schedules. In Study B, 32 males and 39 females aged between 31 and 50 years were exposed once to either clean air, constant or varying concentrations of toluene. Background excretion rate of HA was 0.97 +/- 0.75 mg/min (1.25 +/- 1.05 g/g creatinine) and rose to 3.74 +/- 1.40 mg/min (3.......90 +/- 1.85 g/g cr) during the last 3 h of exposure to 100 ppm toluene. The corresponding figures for O-cr were 0.05 +/- 0.05 micrograms/min (0.08 +/- 0.14 mg/g cr), and 2.04 +/- 0.84 micrograms/min (2.05 +/- 1.18 mg/g cr). The individual creatinine excretion rate was considerably influenced by sex, body...

  3. Photon Propagation in Slowly Varying Electromagnetic Fields

    Science.gov (United States)

    Karbstein, F.

    2017-03-01

    Effective theory of soft photons in slowly varying electromagnetic background fields is studied at one-loop order in QED. This is of relevance for the study of all-optical signatures of quantum vacuum nonlinearity in realistic electromagnetic background fields as provided by high-intensity lasers. The central result derived in this article is a new analytical expression for the photon polarization tensor in two linearly polarized counterpropagating pulsed Gaussian laser beams. Treating the peak field strengths of both laser beams as free parameters, this field configuration can be considered as interpolating between the limiting cases of a purely right- or left-moving laser beam (if one of the peak field strengths is set equal to zero) and the standing-wave type scenario with two counter-propagating beams of equal strength.

  4. Optical vortex array in spatially varying lattice

    CERN Document Server

    Kapoor, Amit; Senthilkumaran, P; Joseph, Joby

    2015-01-01

    We present an experimental method based on a modified multiple beam interference approach to generate an optical vortex array arranged in a spatially varying lattice. This method involves two steps which are: numerical synthesis of a consistent phase mask by using two-dimensional integrated phase gradient calculations and experimental implementation of produced phase mask by utilizing a phase only spatial light modulator in an optical 4f Fourier filtering setup. This method enables an independent variation of the orientation and period of the vortex lattice. As working examples, we provide the experimental demonstration of various spatially variant optical vortex lattices. We further confirm the existence of optical vortices by formation of fork fringes. Such lattices may find applications in size dependent trapping, sorting, manipulation and photonic crystals.

  5. Varied Clinical Manifestations of Amebic Colitis.

    Science.gov (United States)

    Cooper, Chad J; Fleming, Rhonda; Boman, Darius A; Zuckerman, Marc J

    2015-11-01

    Invasive amebiasis is common worldwide, but infrequently observed in the United States. It is associated with considerable morbidity in patients residing in or traveling to endemic areas. We review the clinical and endoscopic manifestations of amebic colitis to alert physicians to the varied clinical manifestations of this potentially life-threatening disease. Copyright ©Most patients present with watery or bloody diarrhea. Less common presentations of amebic colitis include abdominal pain, overt gastrointestinal bleeding, exacerbation of inflammatory bowel disease, or the incidental association with colon cancer. Amebic liver abscesses are the most frequent complication. Rectosigmoid involvement may be found on colonoscopy; however, most case series have reported that the cecum is the most commonly involved site, followed by the ascending colon. Endoscopic evaluation should be used to assist in the diagnosis, with attention to the observation of colonic inflammation, ulceration, and amebic trophozoites on histopathological examination.

  6. Photon propagation in slowly varying electromagnetic fields

    CERN Document Server

    Karbstein, Felix

    2016-01-01

    We study the effective theory of soft photons in slowly varying electromagnetic background fields at one-loop order in QED. This is of relevance for the study of all-optical signatures of quantum vacuum nonlinearity in realistic electromagnetic background fields as provided by high-intensity lasers. The central result derived in this article is a new analytical expression for the photon polarization tensor in two linearly polarized counter-propagating pulsed Gaussian laser beams. As we treat the peak field strengths of both laser beams as free parameters this field configuration can be considered as interpolating between the limiting cases of a purely right- or left-moving laser beam (if one of the peak field strengths is set to zero) and the standing-wave type scenario with two counter-propagating beams of equal strength.

  7. String theory, cosmology and varying constants

    Science.gov (United States)

    Damour, Thibault

    In string theory the coupling `constants' appearing in the low-energy effective Lagrangian are determined by the vacuum expectation values of some (a priori) massless scalar fields (dilaton, moduli). This naturally leads one to expect a correlated variation of all the coupling constants, and an associated violation of the equivalence principle. We review some string-inspired theoretical models which incorporate such a spacetime variation of coupling constants while remaining naturally compatible both with phenomenological constraints coming from geochemical data (Oklo; Rhenium decay) and with present equivalence principle tests. Barring a very unnatural fine-tuning of parameters, a variation of the fine-structure constant as large as that recently `observed' by Webb et al. in quasar absorption spectra appears to be incompatible with these phenomenological constraints. Independently of any model, it is emphasized that the best experimental probe of varying constants are high-precision tests of the universality of free fall, such as MICROSCOPE and STEP.

  8. String theory, cosmology and varying constants

    CERN Document Server

    Damour, Thibault Marie Alban Guillaume

    2002-01-01

    In string theory the coupling ``constants'' appearing in the low-energy effective Lagrangian are determined by the vacuum expectation values of some (a priori) massless scalar fields (dilaton, moduli). This naturally leads one to expect a correlated variation of all the coupling constants, and an associated violation of the equivalence principle. We review some string-inspired theoretical models which incorporate such a spacetime variation of coupling constants while remaining naturally compatible both with phenomenological constraints coming from geochemical data (Oklo; Rhenium decay) and with present equivalence principle tests. Barring a very unnatural fine-tuning of parameters, a variation of the fine-structure constant as large as that recently ``observed'' by Webb et al. in quasar absorption spectra appears to be incompatible with these phenomenological constraints. Independently of any model, it is emphasized that the best experimental probe of varying constants are high-precision tests of the universa...

  9. Decaying Lambda cosmology, varying G and holography

    CERN Document Server

    Carneiro, S

    2004-01-01

    We discuss a class of uniform and isotropic, spatially flat, decaying Lambda cosmologies, in the realm of a model where the gravitation constant G is a function of the cosmological time. Besides the usual de Sitter solution, the models at late times are characterized by a constant ratio between the matter and total energy densities. One of them presents a coasting expansion where the matter density parameter is equal to 1/3, and the age of the universe satisfies Ht = 1. From considerations in line with the holographic conjecture, it is argued that, among the non-decelerating solutions, the coasting expansion is the only acceptable from a thermodynamic viewpoint, and that the time varying cosmological term must be proportional to the square of the Hubble parameter, a result earlier obtained using different arguments.

  10. Time-Varying Graphs and Dynamic Networks

    CERN Document Server

    Casteigts, Arnaud; Quattrociocchi, Walter; Santoro, Nicola

    2010-01-01

    The past few years have seen intensive research efforts carried out in some apparently unrelated areas of dynamic systems -- delay-tolerant networks, opportunistic-mobility networks, social networks -- obtaining closely related insights. Indeed, the concepts discovered in these investigations can be viewed as parts of the same conceptual universe; and the formal models proposed so far to express some specific concepts can be viewed as fragments of a larger formal description of this universe. The main contribution of this paper is to integrate the existing partial models proposed in the literature into a unified framework, which we call TVG (for time-varying graphs). Using this framework, it is possible to express directly in the same formalism not only the concepts common to all those different areas, but also those specific to each. As part of the framework definition, we identify a hierarchy of classes of TVGs, defined with respects to basic properties to which correspond necessary conditions and impossibi...

  11. 19 CFR 159.33 - Proclaimed rate.

    Science.gov (United States)

    2010-04-01

    ... (CONTINUED) LIQUIDATION OF DUTIES Conversion of Foreign Currency § 159.33 Proclaimed rate. If a rate of... currency involved, such proclaimed rate shall be used unless it varies by 5 percent or more from...

  12. Resistance to change varies inversely with reinforcement context.

    Science.gov (United States)

    Grace, Randolph C; Arantes, Joana; Berg, Mark E

    2012-07-01

    We report two experiments which test whether resistance to prefeeding and satiation for a variable-interval (VI) schedule that delivers a constant rate of reinforcement varies inversely with the reinforcement rate for an alternative schedule. In Experiment 1, eight pigeons responded in a multiple schedule in which the red key was always associated with a VI 90-s schedule and the green key with either a richer (VI 18s) or leaner (VI 540s) schedule in different conditions. After baseline training in each condition, prefeeding test sessions were conducted in which 10g, 20g, 30g, 40g, and 50g food were provided one-hour prior to test. Additional baseline training was given between each test session. In Experiment 2, two groups of pigeons responded in a multiple schedule similar to Experiment 1. After baseline training, pigeons were exposed to a 5-h satiation test session in which the VI 90-s schedule was available continuously. Test sessions were conducted when pigeons were maintained at 85%, 95%, and 85% of their body weights in an ABA design. Results of both experiments showed that responding in the VI 90-s schedule that alternated with a leaner schedule during baseline was more resistant to prefeeding and satiation. These data rule out alternative explanations for results of previous studies, and confirm that resistance to change varies inversely with reinforcement context. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Variance Analysis on the Impact of High Savings Rate on the Urban and Rural Population Structure--Based on Time-varying Analysis of the Marginal Propensity to Consume%储蓄率居高的城乡人口结构影响的差异分析--基于边际消费倾向的时变性分析

    Institute of Scientific and Technical Information of China (English)

    瞿凌云

    2015-01-01

    A prominent feature of China’s economic imbalance is the high savings rate. Enhancing theconsumption power helps China’s economyshift to a new normal state on a stable and sustainable basis. Based on the theory of life cycle,the marginal propensity to consume is dynamically solved in this article. And this paper analyzes how it is affect-ed by the income fluctuations and changes in population age structure of the urban and rural areas respectively. The re-search result indicates that the consumption action of the urban residents has a stronger propensity,while the consump-tion level of rural residents has a higher elasticity as the income fluctuates. The impact of the changes in thepopulation age structure is different on the consumption of the rural and urban residents. Rural residents tend to reduce the current consumption to increase savings to cope with old age as the fertility ratio falls continuously. As the social security sys-tem for the urban residents is rather perfect,their motivation to save is small. Meanwhile, as there is a substitution ef-fect of the quantity by the quality of the children, the motivation of the urban residents shows stronger propensity for the education savings and gift savings.%我国经济不平衡的一个突出特点是高储蓄率。提升消费动力有助于我国经济在稳定和可持续的基础上转入新常态。本文以生命周期理论为研究基础,动态求解居民边际消费倾向,分城乡研究了居民收入的波动和人口年龄结构转变对其的影响特点。研究结论表明:城镇居民的消费行为具有较强的惯性,而农村居民消费水平则依据收入波动而呈现较高弹性。人口结构的变化对农村和城镇居民消费的影响也是不一样的,农村居民满足理论规律。在生育率不断下降情况下,农民倾向于降低当期消费而提高储蓄以应付养老。较完善的社保体制导致城镇居民养老储蓄动机较小;由于子

  14. Varying kernel density estimation on ℝ+

    Science.gov (United States)

    Mnatsakanov, Robert; Sarkisian, Khachatur

    2015-01-01

    In this article a new nonparametric density estimator based on the sequence of asymmetric kernels is proposed. This method is natural when estimating an unknown density function of a positive random variable. The rates of Mean Squared Error, Mean Integrated Squared Error, and the L1-consistency are investigated. Simulation studies are conducted to compare a new estimator and its modified version with traditional kernel density construction. PMID:26740729

  15. Time-varying modeling of cerebral hemodynamics.

    Science.gov (United States)

    Marmarelis, Vasilis Z; Shin, Dae C; Orme, Melissa; Rong Zhang

    2014-03-01

    The scientific and clinical importance of cerebral hemodynamics has generated considerable interest in their quantitative understanding via computational modeling. In particular, two aspects of cerebral hemodynamics, cerebral flow autoregulation (CFA) and CO2 vasomotor reactivity (CVR), have attracted much attention because they are implicated in many important clinical conditions and pathologies (orthostatic intolerance, syncope, hypertension, stroke, vascular dementia, mild cognitive impairment, Alzheimer's disease, and other neurodegenerative diseases with cerebrovascular components). Both CFA and CVR are dynamic physiological processes by which cerebral blood flow is regulated in response to fluctuations in cerebral perfusion pressure and blood CO2 tension. Several modeling studies to date have analyzed beat-to-beat hemodynamic data in order to advance our quantitative understanding of CFA-CVR dynamics. A confounding factor in these studies is the fact that the dynamics of the CFA-CVR processes appear to vary with time (i.e., changes in cerebrovascular characteristics) due to neural, endocrine, and metabolic effects. This paper seeks to address this issue by tracking the changes in linear time-invariant models obtained from short successive segments of data from ten healthy human subjects. The results suggest that systemic variations exist but have stationary statistics and, therefore, the use of time-invariant modeling yields "time-averaged models" of physiological and clinical utility.

  16. Microsatellites in varied arenas of research

    Directory of Open Access Journals (Sweden)

    K S Remya

    2010-01-01

    Full Text Available Microsatellites known as simple-sequence repeats (SSRs or short-tandem repeats (STRs, represent specific sequences of DNA consisting of tandemly repeated units of one to six nucleotides. The repetitive nature of microsatellites makes them particularly prone to grow or shrink in length and these changes can have both good and bad consequences for the organisms that possess them. They are responsible for various neurological diseases and hence the same cause is now utilized for the early detection of various diseases, such as, Schizophrenia and Bipolar Disorder, Congenital generalized Hypertrichosis, Asthma, and Bronchial Hyperresponsiveness. These agents are widely used for forensic identification and relatedness testing, and are predominant genetic markers in this area of application. The application of microsatellites is an extending web and covers the varied scenarios of science, such as, conservation biology, plant genetics, and population studies. At present, researches are progressing round the globe to extend the use of these genetic repeaters to unmask the hidden genetic secrets behind the creation of the world.

  17. Comparative Analysis of Frames with Varying Inertia

    Directory of Open Access Journals (Sweden)

    Prerana Nampalli

    2015-01-01

    Full Text Available This paper presents an elastic seismic response of reinforced concrete frames with 3 variations of heights, i.e. (G+2, (G+4, (G+6 storey models are compared for bare frame and frame with brick infill structures which have been analyzed for gravity as well as seismic forces and their response is studied as the geometric parameters varying from view point of predicting behavior of similar structures subjected to similar loads or load combinations. In this study, two different cases are selected i.e. frames with prismatic members and frames with non-prismatic members. The structural response of various members when geometry changes physically, as in case of linear and parabolic haunches provided beyond the face of columns at beam column joints or step variations as in case of stepped haunches was also studied. Frames have been analyzed statically as well as dynamically using ETABS-9.7.4 software referring IS: 456-2000, IS: 1893 (Part-12002 and the results so obtained are grouped into various categories

  18. The Strength of Varying Tie Strength

    CERN Document Server

    Bruggeman, Jeroen

    2012-01-01

    "The Strength of Weak Ties" argument (Granovetter 1973) says that the most valuable information is best collected through bridging ties with other social circles than one's own, and that those ties tend to be weak. Aral and Van Alstyne (2011) added that to access complex information, actors need strong ties ("high bandwidth") instead. These insights I generalize by pointing at actors' interest to avoid spending large resources on low value information. Weak ties are well-suited for relatively simple information at low transmission and tie maintenance costs, whereas for complex information, the best outcomes are expected for those actors who vary their bandwidths along with the value of information accessed. To support my claim I use all patents in the USA (two million) over the period 1975-1999. I also show that in rationalized fields, such as technology, bandwidth correlates highly with the value of information, which provides support for using this proxy if value can't be measured directly. Finally, I show ...

  19. Dermatophyte susceptibility varies towards antimicrobial textiles.

    Science.gov (United States)

    Hammer, Timo R; Mucha, Helmut; Hoefer, Dirk

    2012-07-01

    Dermatophytoses are a widespread problem worldwide. Textiles in contact with infected skin can serve as a carrier for fungus propagation. Hitherto, it is unknown, whether antifungal textiles could contribute in controlling dermatophytes e.g. by disrupting the chain of infection. Testing of antimicrobial fabrics for their antifungal activities therefore is a fundamental prerequisite to assess the putative clinical relevance of textiles for dermatophyte prevention. Fabrics finished with either didecyldimethylammonium chloride (DDAC), poly-hexamethylenbiguanide, copper and two silver chloride concentrations were tested for their antifungal activity against Trichophyton rubrum, Trichophyton mentagrophytes and Candida albicans. To prove dermatophyte susceptibility towards the textiles, swatches were subjected to DIN EN 14199 (Trichophyton sp.) or DIN EN ISO 20743 (C. albicans) respectively. In addition, samples were embedded, and semi-thin sections were analysed microscopically. While all samples showed a clear inhibition of C. albicans, activity against Trichophyton sp. varied significantly: For example, DDAC completely inhibited T. rubrum growth, whereas T. mentagrophytes growth remained unaffected even in direct contact to the fibres. The results favour to add T. mentagrophytes as a test organism in textile dermatophyte efficacy tests. Microscopic analysis of swatches allowed detailed evaluation of additional parameters like mycelium thickness, density and hyphae penetration depth into the fabric.

  20. Varied acceptance of clinical trial results.

    Science.gov (United States)

    Klimt, C R

    1989-12-01

    The subject of varied acceptance of clinical trial results is discussed in the context of review of trials with which I have been involved and my subjective evaluation of their impact on the practice of clinical medicine. My experience goes back to 1949 and a World Health Organization trial of hyperimmune gamma globulin against rabies. This was followed by a large trial of secondary prevention of poliomyelitis. I participated in the planning and initiation of the first chronic disease trial, the University Group Diabetes Program (UGDP). The latter lasted for 15 years and its ramifications continue to this day. My next trial was the Coronary Drug Project (CDP), a complex trial with more than 8,000 patients. The trials of aspirin and aspirin combined with persantine (the CDPA, AMIS, PARIS I, and PARIS II) followed. My last three trials were a trial of photocoagulation in diabetic retinopathy (DRS), a six-country trial of the antiarrhythmic drug mexiletine (IMPACT), and a study involving two diagnostic procedures for pulmonary embolism (PIOPED). When one considers, in retrospect, the plethora of trials one is struck by the uniform absence of a priori considerations of the impact on medical practice, or likely lack thereof, of possible outcomes.

  1. A Generalized Theory of Varying Alpha

    CERN Document Server

    Barrow, John D

    2011-01-01

    In this paper, we formulate a generalization of the simple Bekenstein-Sandvik-Barrow-Magueijo (BSBM) theory of varying alpha by allowing the coupling constant, \\omega, for the corresponding scalar field \\psi\\ to depend on \\psi. We focus on the situation where \\omega\\ is exponential in \\psi\\ and find the late-time behaviours that occur in matter-dominated and dark-energy dominated cosmologies. We also consider the situation when the background expansion scale factor of the universe evolves in proportion to an arbitrary power of the cosmic time. We find the conditions under which the fine structure `constant' increases with time, as in the BSBM theory, and establish a cosmic no-hair behaviour for accelerating universes. We also find the conditions under which the fine structure `constant' can decrease with time and compare the whole family of models with astronomical data from quasar absorption spectra. Finally, we show that spatial variations on sub-horizon scales can dominate over the cosmological time evolut...

  2. Antiorthostatic immobilization with varied sodium intake

    Science.gov (United States)

    Hinghofer-Szalkay, H.; Haditsch, B.; Pilz, K.; Rössler, A.; Laszlo, Z.

    The study investigated, in 10 normotensive male persons, heart rate responses to graded lower body suction (LBNP) with adaptation to various oral sodium clamping during both ambulatory (AMB) conditions for 4 days, and thereafter to additional antiorthostatic (6° head down) positioning. A ,low' (LS: 143+/-10 mM Na +/ d excreted) and a ,high' (HS: 434+/-17 mM Na +/d excreted) sodium treatment - in randomized order and separated =1 mo - followed a ,conditioning' run with moderate sodium (237+/-9 mM Na +/d excreted). Urinary volume and sodium output were monitored, hormone levels (PRA, aldosterone, AVP) determined, and extracellular volume (ECV) estimated by whole body electrical impedance spectroscopy. ECV was not differently reduced (p>0.1) in LS (-5.8+/-2.3%, p=0.018) and HS (-4.0+/-1.0%. p=0.002). Morning AVP was lower (5.5+/-0.1 pg/ml) in HS than in LS (7.2+/-0.3 pg/ml; N=7 days), as well as aldosterone (69+/-7 pg/ml in HS vs. 180+/-24 pg/ml in LS). LBNP dose responses of PRA and aldosterone were higher in LS than HS after 8 days AOB, whereas microvascular fluid filtration was unchanged by any experimental condition. Heart rate responses to LBNP were unchanged by sodium supply, whereas mean arterial and pulse pressure was lower in LS than HS during all LBNP intensities. Thus, HS was able to increase arterial blood and pulse pressure and reduced PRA and aldosterone levels during graded simulated orthostatic challenge, but did neither ameliorate AOB-induced ECV decrease nor alter LBNP-induced filtration and heart rate responses. These results are relevant for planning of future countermeasures in astronauts. Supported by the Austrian Research Fund (P13451-MED)

  3. Functional Piezocrystal Characterisation under Varying Conditions

    Directory of Open Access Journals (Sweden)

    Xiaochun Liao

    2015-12-01

    Full Text Available Piezocrystals, especially the relaxor-based ferroelectric crystals, have been subject to intense investigation and development within the past three decades, motivated by the performance advantages offered by their ultrahigh piezoelectric coefficients and higher electromechanical coupling coefficients than piezoceramics. Structural anisotropy of piezocrystals also provides opportunities for devices to operate in novel vibration modes, such as the d36 face shear mode, with domain engineering and special crystal cuts. These piezocrystal characteristics contribute to their potential usage in a wide range of low- and high-power ultrasound applications. In such applications, conventional piezoelectric materials are presently subject to varying mechanical stress/pressure, temperature and electric field conditions. However, as observed previously, piezocrystal properties are significantly affected by a single such condition or a combination of conditions. Laboratory characterisation of the piezocrystal properties under these conditions is therefore essential to fully understand these materials and to allow electroacoustic transducer design in realistic scenarios. This will help to establish the extent to which these high performance piezocrystals can replace conventional piezoceramics in demanding applications. However, such characterisation requires specific experimental arrangements, examples of which are reported here, along with relevant results. The measurements include high frequency-resolution impedance spectroscopy with the piezocrystal material under mechanical stress 0–60 MPa, temperature 20–200 °C, high electric AC drive and DC bias. A laser Doppler vibrometer and infrared thermal camera are also integrated into the measurement system for vibration mode shape scanning and thermal conditioning with high AC drive. Three generations of piezocrystal have been tested: (I binary, PMN-PT; (II ternary, PIN-PMN-PT; and (III doped ternary, Mn

  4. How specific halide adsorption varies hydrophobic interactions.

    Science.gov (United States)

    Stock, Philipp; Müller, Melanie; Utzig, Thomas; Valtiner, Markus

    2016-03-11

    Hydrophobic interactions (HI) are driven by the water structure around hydrophobes in aqueous electrolytes. How water structures at hydrophobic interfaces and how this influences the HI was subject to numerous studies. However, the effect of specific ion adsorption on HI and hydrophobic interfaces remains largely unexplored or controversial. Here, the authors utilized atomic force microscopy force spectroscopy at well-defined nanoscopic hydrophobic interfaces to experimentally address how specific ion adsorption of halide ions as well as NH4 (+), Cs(+), and Na(+) cations alters interaction forces across hydrophobic interfaces. Our data demonstrate that iodide adsorption at hydrophobic interfaces profoundly varies the hydrophobic interaction potential. A long-range and strong hydration repulsion at distances D > 3 nm, is followed by an instability which could be explained by a subsequent rapid ejection of adsorbed iodides from approaching hydrophobic interfaces. In addition, the authors find only a weakly pronounced influence of bromide, and as expected no influence of chloride. Also, all tested cations do not have any significant influence on HI. Complementary, x-ray photoelectron spectroscopy and quartz-crystal-microbalance with dissipation monitoring showed a clear adsorption of large halide ions (Br(-)/I(-)) onto hydrophobic self-assembled monolayers (SAMs). Interestingly, iodide can even lead to a full disintegration of SAMs due to specific and strong interactions of iodide with gold. Our data suggest that hydrophobic surfaces are not intrinsically charged negatively by hydroxide adsorption, as it was generally believed. Hydrophobic surfaces rather interact strongly with negatively charged large halide ions, leading to a surface charging and significant variation of interaction forces.

  5. Song trait similarity in great tits varies with social structure.

    Directory of Open Access Journals (Sweden)

    Lysanne Snijders

    Full Text Available For many animals, long-range signalling is essential to maintain contact with conspecifics. In territorial species, individuals often have to balance signalling towards unfamiliar potential competitors (to solely broadcast territory ownership with signalling towards familiar immediate neighbours (to also maintain so-called "dear enemy" relations. Hence, to understand how signals evolve due to these multilevel relationships, it is important to understand how general signal traits vary in relation to the overall social environment. For many territorial songbirds dawn is a key signalling period, with several neighbouring individuals singing simultaneously without immediate conflict. In this study we tested whether sharing a territory boundary, rather than spatial proximity, is related to similarity in dawn song traits between territorial great tits (Parus major in a wild personality-typed population. We collected a large dataset of automatized dawn song recordings from 72 unique male great tits, during the fertile period of their mate, and compared specific song traits between neighbours and non-neighbours. We show here that both song rate and start time of dawn song were repeatable song traits. Moreover, neighbours were significantly more dissimilar in song rate compared to non-neighbours, while there was no effect of proximity on song rate similarity. Additionally, similarity in start time of dawn song was unrelated to sharing a territory boundary, but birds were significantly more similar in start time of dawn song when they were breeding in close proximity of each other. We suggest that the dissimilarity in dawn song rate between neighbours is either the result of neighbouring great tits actively avoiding similar song rates to possibly prevent interference, or a passive consequence of territory settlement preferences relative to the types of neighbours. Neighbourhood structuring is therefore likely to be a relevant selection pressure shaping

  6. Song trait similarity in great tits varies with social structure.

    Science.gov (United States)

    Snijders, Lysanne; van der Eijk, Jerine; van Rooij, Erica P; de Goede, Piet; van Oers, Kees; Naguib, Marc

    2015-01-01

    For many animals, long-range signalling is essential to maintain contact with conspecifics. In territorial species, individuals often have to balance signalling towards unfamiliar potential competitors (to solely broadcast territory ownership) with signalling towards familiar immediate neighbours (to also maintain so-called "dear enemy" relations). Hence, to understand how signals evolve due to these multilevel relationships, it is important to understand how general signal traits vary in relation to the overall social environment. For many territorial songbirds dawn is a key signalling period, with several neighbouring individuals singing simultaneously without immediate conflict. In this study we tested whether sharing a territory boundary, rather than spatial proximity, is related to similarity in dawn song traits between territorial great tits (Parus major) in a wild personality-typed population. We collected a large dataset of automatized dawn song recordings from 72 unique male great tits, during the fertile period of their mate, and compared specific song traits between neighbours and non-neighbours. We show here that both song rate and start time of dawn song were repeatable song traits. Moreover, neighbours were significantly more dissimilar in song rate compared to non-neighbours, while there was no effect of proximity on song rate similarity. Additionally, similarity in start time of dawn song was unrelated to sharing a territory boundary, but birds were significantly more similar in start time of dawn song when they were breeding in close proximity of each other. We suggest that the dissimilarity in dawn song rate between neighbours is either the result of neighbouring great tits actively avoiding similar song rates to possibly prevent interference, or a passive consequence of territory settlement preferences relative to the types of neighbours. Neighbourhood structuring is therefore likely to be a relevant selection pressure shaping variation in

  7. EOQ Models with Varying Holding Cost

    Directory of Open Access Journals (Sweden)

    Naser Ghasemi

    2013-01-01

    Full Text Available Models of inventory management contain different parameters. An issue is observable in the classical models which can be related to the determination of the quantity of the economic order and the quantity of the economic production. In these models, the parameters like setup and holding costs and also the rate of demands are fixed. This matter causes the quantity of the economic ordering in classic model to have some differences in comparison with the real-world conditions. It should be stated that holding cost of spoiled and useless products is not always fixed and so the costs increase by passing the time. This paper is an attempt to develop classical EOQ models by considering holding cost as an increasing function of the ordering cycle length. So the classical EOQ models are developed, and the related optimum quantity to the ordering cycle length, economic ordering quantity, and the optimum total cost are determined.

  8. Psycho-Physical Effects of Varied Rest Intervals Following Warm-Up.

    Science.gov (United States)

    Aronchick, Joel; Burke, Edmund J.

    This study assessed the effects of varied rest intervals following a five-minute warm-up upon subsequent ratings of perceived exertion (RPE), heart rate (HR), and state anxiety during an exercise period. The subjects were 16 male college students. Each subject was tested under four experimental conditions following a five-minute warm-up on a…

  9. Immune response varies with rate of dispersal in invasive cane toads (Rhinella marina.

    Directory of Open Access Journals (Sweden)

    Gregory P Brown

    Full Text Available What level of immunocompetence should an animal maintain while undertaking long-distance dispersal? Immune function (surveillance and response might be down-regulated during prolonged physical exertion due to energy depletion, and/or to avoid autoimmune reactions arising from damaged tissue. On the other hand, heightened immune vigilance might be favored if the organism encounters novel pathogens as it enters novel environments. We assessed the links between immune defense and long-distance movement in a population of invasive cane toads (Rhinella marina in Australia. Toads were radio-tracked for seven days to measure their activity levels and were then captured and subjected to a suite of immune assays. Toads that moved further showed decreased bacteria-killing ability in their plasma and decreased phagocytic activity in their whole blood, but a heightened skin-swelling response to phytohemagglutinin. Baseline and post-stress corticosterone levels were unrelated to distance moved. Thus, long-distance movement in cane toads is associated with a dampened response in some systems and enhanced response in another. This pattern suggests that sustained activity is accompanied by trade-offs among immune components rather than an overall down or up-regulation. The finding that high mobility is accompanied by modification of the immune system has important implications for animal invasions.

  10. Rate bounded linear parameter varying control of a wind turbine in full load operation

    DEFF Research Database (Denmark)

    Østergaard, Kasper Zinck; Stoustrup, Jakob; Brath, Per

    2008-01-01

    This paper considers the control of wind turbines using an LPV design technique. The controller design is done by a combination of a method that uses elimination of controller variables and a method using a congruent transformation followed by a change of variables. An investigation is performed ...

  11. Study of the Progressive Failure of Composites under Axial Loading with Varying Strain Rates

    Science.gov (United States)

    2011-12-01

    2. Test Specimen Geometries ................................................................19 3. Vacuum-Assisted Resin Transfer Molding ( VARTM ...20 Figure 14. Main components of the VARTM ...Molding ( VARTM ) Vacuum-Assisted Resin Transfer Molding is a process which involves placing dry fibers in a mold and adding the resin separately. The

  12. Ratings of Perceived Exertion of ACSM Exercise Guidelines in Individuals Varying in Aerobic Fitness

    Science.gov (United States)

    Kaufman, Christopher; Berg, Kris; Noble, John; Thomas, James

    2006-01-01

    The physiological responses of high (HF) and low fit (LF) individuals at given perceived exercise intensities were compared to ranges provided by the American College of Sports Medicine (ACSM). Participants were 7 LF and 8 HF men between the ages of 22 and 26 years. All participants performed a maximum oxygen uptake and lactate threshold test and…

  13. Youth Walking and Biking Rates Vary by Environments around 5 Louisiana Schools

    Science.gov (United States)

    Gustat, Jeanette; Richards, Katherine; Rice, Janet; Andersen, Lori; Parker-Karst, Kathryn; Cole, Shalanda

    2015-01-01

    Background: The prevalence of obesity in children is high, and many do not meet physical activity recommendations. The Safe Routes to School (SRTS) program encourages school-aged children to walk and bike to school. We assessed the condition of the walking/biking environment around schools in Louisiana prior to the state's first SRTS program.…

  14. Bifurcation of Positive Equilibria in Nonlinear Structured Population Models with Varying Mortality Rates

    CERN Document Server

    Walker, Christoph

    2010-01-01

    A parameter-dependent model involving nonlinear diffusion for an age-structured population is studied. The parameter measures the intensity of the mortality. A bifurcation approach is used to establish existence of positive equilibrium solutions.

  15. Robust and Optimal Control of Magnetic Microparticles inside Fluidic Channels with Time-Varying Flow Rates

    NARCIS (Netherlands)

    Khalil, I.S.M.; Abass, Hazem; Shoukry, Mostafa; Klingner, Anke; El-Nashar, Rasha M.; Serry, Mohamed; Misra, Sarthak

    2016-01-01

    Targeted therapy using magnetic microparticles and nanoparticles has the potential to mitigate the negative side-effects associated with conventional medical treatment. Major technological challenges still need to be addressed in order to translate these particles into in vivo applications. For

  16. The evolution of white dwarfs with a varying gravitational constant

    CERN Document Server

    Althaus, L G; Torres, S; Loren-Aguilar, P; Isern, J; Garcia-Berro, E

    2011-01-01

    Within the theoretical framework of some modern unification theories the constants of nature are functions of cosmological time. White dwarfs offer the possibility of testing a possible variation of G and, thus, to place constraints to these theories. We present full white dwarf evolutionary calculations in the case that G decreases with time. White dwarf evolution is computed in a self-consistent way, including the most up-to-date physical inputs, non-gray model atmospheres and a detailed core chemical composition that results from the calculation of the full evolution of progenitor stars. We find that the mechanical structure and the energy balance of white dwarfs are strongly modified by the presence of a varying G. In particular, for certain values of the rate of change of G, the evolution of cool white dwarfs is markedly affected. The impact of a varying G is more notorious in the case of more massive white dwarfs. In view of the recent results reporting that a very accurate white dwarf cooling age can b...

  17. Reducing component estimation for varying coefficient models with longitudinal data

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Varying-coefficient models with longitudinal observations are very useful in epidemiology and some other practical fields.In this paper,a reducing component procedure is proposed for es- timating the unknown functions and their derivatives in very general models,in which the unknown coefficient functions admit different or the same degrees of smoothness and the covariates can be time- dependent.The asymptotic properties of the estimators,such as consistency,rate of convergence and asymptotic distribution,are derived.The asymptotic results show that the asymptotic variance of the reducing component estimators is smaller than that of the existing estimators when the coefficient functions admit different degrees of smoothness.Finite sample properties of our procedures are studied through Monte Carlo simulations.

  18. Projection-type estimation for varying coefficient regression models

    CERN Document Server

    Lee, Young K; Park, Byeong U; 10.3150/10-BEJ331

    2012-01-01

    In this paper we introduce new estimators of the coefficient functions in the varying coefficient regression model. The proposed estimators are obtained by projecting the vector of the full-dimensional kernel-weighted local polynomial estimators of the coefficient functions onto a Hilbert space with a suitable norm. We provide a backfitting algorithm to compute the estimators. We show that the algorithm converges at a geometric rate under weak conditions. We derive the asymptotic distributions of the estimators and show that the estimators have the oracle properties. This is done for the general order of local polynomial fitting and for the estimation of the derivatives of the coefficient functions, as well as the coefficient functions themselves. The estimators turn out to have several theoretical and numerical advantages over the marginal integration estimators studied by Yang, Park, Xue and H\\"{a}rdle [J. Amer. Statist. Assoc. 101 (2006) 1212--1227].

  19. MIMO Multiple Access Channel with an Arbitrarily Varying Eavesdropper

    CERN Document Server

    He, Xiang; Yener, Aylin

    2012-01-01

    A two-transmitter Gaussian multiple access wiretap channel with multiple antennas at each of the nodes is investigated. The channel matrices at the legitimate terminals are fixed and revealed to all the terminals, whereas the channel matrix of the eavesdropper is arbitrarily varying and only known to the eavesdropper. The secrecy degrees of freedom (s.d.o.f.) region under a strong secrecy constraint is characterized. A transmission scheme that orthogonalizes the transmit signals of the two users at the intended receiver and uses a single-user wiretap code is shown to be sufficient to achieve the s.d.o.f. region. The converse involves establishing an upper bound on a weighted-sum-rate expression. This is accomplished by using induction, where at each step one combines the secrecy and multiple-access constraints associated with an adversary eavesdropping a carefully selected group of sub-channels.

  20. Identification and robust control of linear parameter-varying systems

    Science.gov (United States)

    Lee, Lawton Hubert

    This dissertation deals with linear parameter-varying (LPV) systems: linear dynamic systems that depend on time-varying parameters. These systems appear in gain scheduling problems, and much recent research has been devoted to their prospective usefulness for systematic gain scheduling. We primarily focus on robust control of uncertain LPV systems and identification of LPV systems that are modelable as linear-fractional transformations (LFTs). Using parameter-dependent quadratic Lyapunov functions, linear matrix inequalities (LMIs), and scaled small-gain arguments, we define notions of stability and induced-{cal L}sb2 performance for uncertain LPV systems whose parameters and rates of parameter variation satisfy given bounds. The performance criterion involves integral quadratic constraints and implies naturally parameter-dependent induced-{cal L}sb2 norm bounds. We formulate and solve an {cal H}sb{infty}-like control problem for an LPV plant with measurable parameters and an "Output/State Feedback" structure: the feedback outputs include some noiselessly measured states. Necessary and sufficient solvability conditions reduce to LMIs that can be solved approximately using finite-dimensional convex programming. Reduced-order LPV controllers are constructed from the LMI solutions. A D-K iteration-like procedure provides robustness to structured, time-varying, parametric uncertainty. The design method is applied to a motivating example: flight control for the F-16 VISTA throughout its subsonic flight envelope. Parameter-dependent weights and {cal H}sb{infty} design principles describe the performance objectives. Closed-loop responses exhibited by nonlinear simulations indicate satisfactory flying qualities. Identification of linear-fractional LPV systems is treated using maximum-likelihood parameter estimation. Computing the gradient and Hessian of a maximum-likelihood cost function reduces to simulating one LPV filter per identified parameter. We use nonlinear

  1. Development of a Passively Varying Pitch Propeller

    Science.gov (United States)

    Heinzen, Stearns Beamon

    compared to the fixed pitch propellers currently used on most light aircraft and small unmanned systems, making significant improvements in aircraft performance possible. These improvements may yield aircraft with reduced takeoff distances, improved climb rates, increased range and endurance, and higher top speeds, without sacrificing on-design performance.

  2. LMI-based gain scheduled controller synthesis for a class of linear parameter varying systems

    DEFF Research Database (Denmark)

    Bendtsen, Jan Dimon; Anderson, Brian; Lanzon, Alexander

    2006-01-01

    This paper presents a novel method for constructing controllers for a class of single-input multiple-output (SIMO) linear parameter varying (LPV) systems. This class of systems encompasses many physical systems, in particular systems where individual components vary with time, and is therefore...... the parameters are varying, with the degree of stability related directly to a bound on the average rate of allowable parameter variations. Thus, if knowledge of the parameter variations is available, the conservativeness of the design can be kept at a minimum. The construction of the controller is formulated...

  3. Colorectal Cancer Rates by Race and Ethnicity

    Science.gov (United States)

    ... Associated Lung Ovarian Prostate Skin Uterine Cancer Home Colorectal Cancer Rates by Race and Ethnicity Language: English (US) ... Tweet Share Compartir The rate of people getting colorectal cancer or dying from colorectal cancer varies by race ...

  4. Lung Cancer Rates by Race and Ethnicity

    Science.gov (United States)

    ... HPV-Associated Ovarian Prostate Skin Uterine Cancer Home Lung Cancer Rates by Race and Ethnicity Language: English Español ( ... Tweet Share Compartir The rate of people getting lung cancer or dying from lung cancer varies by race ...

  5. TESTS FOR VARIANCE COMPONENTS IN VARYING COEFFICIENT MIXED MODELS

    National Research Council Canada - National Science Library

    Zaixing Li; Yuedong Wang; Ping Wu; Wangli Xu; Lixing Zhu

    2012-01-01

    .... To address the question of whether a varying coefficient mixed model can be reduced to a simpler varying coefficient model, we develop one-sided tests for the null hypothesis that all the variance components are zero...

  6. Tissue effects of Ho:YAG laser with varying fluences and pulse widths

    Science.gov (United States)

    Vari, Sandor G.; van der Veen, Maurits J.; Pergadia, Vani R.; Shi, Wei-Qiang; Duffy, J. T.; Weiss, Andrew B.; Fishbein, Michael C.; Grundfest, Warren S.

    1994-02-01

    We investigated the effect of varying fluence and pulse width on the ablation rate and consequent thermal damage of the Ho:YAG (2.130 micrometers ) laser. The rate of ablation on fresh bovine knee joint tissues, fibrous cartilage, hyaline cartilage, and bone in saline was determined after varying the fluence (160 - 640 J/cm2) and pulse width (150, 250, 450 microsecond(s) ec, FWHM) at a repetition rate of 2 Hz. A 400/440 micrometers fiber was used. The ablation rate increased linearly with the fluence. In fibrocartilage, different pulse durations generated significant changes in the ablation rates, but showed minor effects on hyaline cartilage and bone. The heat of ablation for all three tissue types decreased after lengthening the pulse.

  7. Comparison of Linear Microinstability Calculations of Varying Input Realism

    Energy Technology Data Exchange (ETDEWEB)

    G. Rewoldt

    2003-09-08

    The effect of varying ''input realism'' or varying completeness of the input data for linear microinstability calculations, in particular on the critical value of the ion temperature gradient for the ion temperature gradient mode, is investigated using gyrokinetic and gyrofluid approaches. The calculations show that varying input realism can have a substantial quantitative effect on the results.

  8. Long-time behavior of a stochastic epidemic model with varying population size

    Science.gov (United States)

    Wei, Fengying; Liu, Jiamin

    2017-03-01

    In this paper we investigate the persistence and extinction of a stochastic epidemic model with a varying population environment in the long-term behavior. Our model consists of two stochastic differential equations: one for the susceptible individuals in which the transmission rate is disturbed by white noise, one for the exposed individuals in which the same perturbation occurs, and one ordinary differential equation in which describes the infective individuals in a varying population environment. We derive sufficient conditions for the extinction and persistence of the epidemic model depending on the constant contact rate. Moreover, we carry out several numerical simulations to illustrate the main results of this contribution.

  9. Time-varying trends of global vegetation activity

    Science.gov (United States)

    Pan, N.; Feng, X.; Fu, B.

    2016-12-01

    Vegetation plays an important role in regulating the energy change, water cycle and biochemical cycle in terrestrial ecosystems. Monitoring the dynamics of vegetation activity and understanding their driving factors have been an important issue in global change research. Normalized Difference Vegetation Index (NDVI), an indicator of vegetation activity, has been widely used in investigating vegetation changes at regional and global scales. Most studies utilized linear regression or piecewise linear regression approaches to obtain an averaged changing rate over a certain time span, with an implicit assumption that the trend didn't change over time during that period. However, no evidence shows that this assumption is right for the non-linear and non-stationary NDVI time series. In this study, we adopted the multidimensional ensemble empirical mode decomposition (MEEMD) method to extract the time-varying trends of NDVI from original signals without any a priori assumption of their functional form. Our results show that vegetation trends are spatially and temporally non-uniform during 1982-2013. Most vegetated area exhibited greening trends in the 1980s. Nevertheless, the area with greening trends decreased over time since the early 1990s, and the greening trends have stalled or even reversed in many places. Regions with browning trends were mainly located in southern low latitudes in the 1980s, whose area decreased before the middle 1990s and then increased at an accelerated rate. The greening-to-browning reversals were widespread across all continents except Oceania (43% of the vegetated areas), most of which happened after the middle 1990s. In contrast, the browning-to-greening reversals occurred in smaller area and earlier time. The area with monotonic greening and browning trends accounted for 33% and 5% of the vegetated area, respectively. By performing partial correlation analyses between NDVI and climatic elements (temperature, precipitation and cloud cover

  10. Time Frequency Features of Rotor Systems with Slowly Varying Mass

    Directory of Open Access Journals (Sweden)

    Tao Yu

    2011-01-01

    Full Text Available With the analytic method and numerical method respectively, the asymptotic solutions and finite element model of rotor system with single slowly varying mass is obtained to investigate the time frequency features of such rotor system; furthermore, with given model of slowly varying mass, the rotor system with dual slowly varying mass is studied. For the first order approximate solution is used, there exists difference between the results with analytic method and numerical method. On the base of common characteristics of rotor system with dual slowly varying mass, the general rules and formula describing the frequency distribution of rotor system with multiple slowly varying mass are proposed.

  11. Holographic cinematography of time-varying reflecting and time-varying phase objects using a Nd:YAG laser

    Science.gov (United States)

    Decker, A. J.

    1982-01-01

    The use of a Nd:YAG laser to record holographic motion pictures of time-varying reflecting objects and time-varying phase objects is discussed. Sample frames from both types of holographic motion pictures are presented. The holographic system discussed is intended for three-dimensional flow visualization of the time-varying flows that occur in jet-engine components.

  12. Ratings Revisited

    DEFF Research Database (Denmark)

    Lai, Signe Sophus

    2015-01-01

    tværs af medier og platforme, forskudt i tid og on-demand. This article focuses on audience ratings, which have functioned as the central ‘currency’ informing the media trade. It discusses changes to the production and accuracy of audience ratings at a time when established standards are being...... consumption. It argues that current tracking systems cannot capture increasingly cross-media, time-shifted, mobile, and on-demand audience behavior....

  13. Temperature Responses of Soil Organic Matter Components With Varying Recalcitrance

    Science.gov (United States)

    Simpson, M. J.; Feng, X.

    2007-12-01

    The response of soil organic matter (SOM) to global warming remains unclear partly due to the chemical heterogeneity of SOM composition. In this study, the decomposition of SOM from two grassland soils was investigated in a one-year laboratory incubation at six different temperatures. SOM was separated into solvent- extractable compounds, suberin- and cutin-derived compounds, and lignin monomers by solvent extraction, base hydrolysis, and CuO oxidation, respectively. These SOM components had distinct chemical structures and recalcitrance, and their decomposition was fitted by a two-pool exponential decay model. The stability of SOM components was assessed using geochemical parameters and kinetic parameters derived from model fitting. Lignin monomers exhibited much lower decay rates than solvent-extractable compounds and a relatively low percentage of lignin monomers partitioned into the labile SOM pool, which confirmed the generally accepted recalcitrance of lignin compounds. Suberin- and cutin-derived compounds had a poor fitting for the exponential decay model, and their recalcitrance was shown by the geochemical degradation parameter which stabilized during the incubation. The aliphatic components of suberin degraded faster than cutin-derived compounds, suggesting that cutin-derived compounds in the soil may be at a higher stage of degradation than suberin- derived compounds. The temperature sensitivity of decomposition, expressed as Q10, was derived from the relationship between temperature and SOM decay rates. SOM components exhibited varying temperature responses and the decomposition of the recalcitrant lignin monomers had much higher Q10 values than soil respiration or the solvent-extractable compounds decomposition. Our study shows that the decomposition of recalcitrant SOM is highly sensitive to temperature, more so than bulk soil mineralization. This observation suggests a potential acceleration in the degradation of the recalcitrant SOM pool with global

  14. Dynamic Analysis of Integrally Geared Compressors with Varying Workloads

    Directory of Open Access Journals (Sweden)

    Ming Zhang

    2016-01-01

    Full Text Available Integrally geared compressors are characterized by compact and high efficiency machines, which are widely used in modern processing industries. As an important part of integrally geared compressors, a geared rotor-bearing system exhibits complicated dynamic behaviors. When running at rated speeds, a coupling system likely produces resonance with an adjusted workload, and a critical load phenomenon occurs. The dynamic coefficients of bearings, axial force and torque, and gear meshing stiffness vary with workload because of the interaction between rotors. In this study, a dynamic model of a geared rotor-bearing system influenced by the dynamic coefficients of bearings, axial force and torque, and gear meshing stiffness is developed. The dynamic responses of the coupling system are calculated and analyzed by using a typical five-shaft integrally geared compressor as an example. The effects of different parameters on the dynamic behaviors of the proposed system are also considered in the discussion. The geared rotor-bearing system is further investigated to examine the failure mechanism of the critical load.

  15. Spatially Varying Determinants of Farmland Conversion Across Qiantang Watershed, China

    Science.gov (United States)

    Su, Shiliang; Xiao, Rui

    2013-10-01

    This paper employed geographically weighted regression (GWR) to characterize the determinants of farmland conversion at administrative scale between 1994 and 2003 across Qiantang watershed, China. Six determinants were identified: total area of forest, distance to highway, distance to second road, distance to river, population, and gross domestic product. Relationships between these identified determinants and farmland conversion showed great spatial non-stationarity, since their character, nature, and strength varied significantly across space. Typically, for cities whose development was heavily relied on road infrastructure development, the impacts of "distance to second road" and "distance to river" was negative. However, in mountainous areas, the restriction of terrain factors led to positive impacts from these two variables. For areas undergoing rapid socio-economic development, farmland conversion was accelerated by population growth and economic development. However, for more urbanized regions, a slow-down rate of farmland conversion would be expected. Our study highlighted that the problem of spatial non-stationarity should be addressed when qualifying the determinants of farmland conversion. Linking our results within the context of farmland protection, we argue that implementing local-specific land management practices, instead of the current one-size-fits-all framework, is the key for the success of farmland protection in China.

  16. Cold surge: a sudden and spatially varying threat to health?

    Science.gov (United States)

    Yang, Tse-Chuan; Wu, Pei-Chih; Chen, Vivian Yi-Ju; Su, Huey-Jen

    2009-05-01

    While cold surge is one of the most conspicuous features of the winter monsoon in East Asia, its impact on human health remains underexplored. Based on the definition by the Central Weather Bureau in Taiwan, we identified four cold surges between 2000 and 2003 and collected the cardiovascular disease mortality data 2 weeks before and 2 weeks after these events. We attempted to answer the following research questions: 1) whether the cold surges impose an adverse and immediate effect on cardiovascular mortality; 2) whether the people living in temperate zones have a higher tolerance of extreme temperature drop than those in the subtropics. With geographic weighting techniques, we not only found that the cardiovascular disease mortality rates increased significantly after the cold surges, but also discovered a spatially varying pattern of tolerance to cold surges. Even within a small study area such as Taiwan, human reaction to severe weather drop differs across space. Needless to say, in the U.S., these findings should be considered in redirecting policy to address populations living in warm places when extreme temperature drops occur.

  17. Varying electric charge in multi-scale spacetimes

    CERN Document Server

    Calcagni, Gianluca; Fernández, David Rodríguez

    2014-01-01

    We derive the covariant equations of motion for Maxwell field theory and electrodynamics in multi-scale spacetimes with weighted Laplacian. An effective spacetime-dependent electric charge of geometric origin naturally emerges from the theory, thus giving rise to a varying fine-structure constant. The theory is compared with other varying-coupling models, such as those with a varying electric charge or varying speed of light. The theory is also confronted with cosmological observations, which can place constraints on the characteristic scales in the multi-fractional measure. We note that the model considered here is fundamentally different from those previously proposed in the literature, either of the varying-e or varying-c persuasion.

  18. Children's Faithfulness in Imitating Language Use Varies Cross-culturally, Contingent on Prior Experience

    Science.gov (United States)

    Klinger, Jörn; Mayor, Julien; Bannard, Colin

    2016-01-01

    Despite its recognized importance for cultural transmission, little is known about the role imitation plays in language learning. Three experiments examine how rates of imitation vary as a function of qualitative differences in the way language is used in a small indigenous community in Oaxaca, Mexico and three Western comparison groups. Data from…

  19. Landscape forest cover and edge effects on songbird nest predation vary by nest predator

    Science.gov (United States)

    W. Andrew Cox; Frank R. III Thompson; John. Faaborg

    2012-01-01

    Rates of nest predation for birds vary between and within species across multiple spatial scales, but we have a poor understanding of which predators drive such patterns. We video-monitored nests and identified predators at 120 nests of the Acadian Flycatcher (Empidonax virescens) and the Indigo Bunting (Passerina cyanea) at eight...

  20. Public School Aggression among Children with Varying Day-Care Experience.

    Science.gov (United States)

    Haskins, Ron

    1985-01-01

    Fifty-nine children with varying amounts and types of day-care experience were followed over their first 2 or 3 years of public schooling. Schoolteachers rated aggressiveness of several types and in several situations and supplied information about managing the children, their use of conflict-avoiding strategies, and other associated skills and…

  1. Children's Faithfulness in Imitating Language Use Varies Cross-culturally, Contingent on Prior Experience

    Science.gov (United States)

    Klinger, Jörn; Mayor, Julien; Bannard, Colin

    2016-01-01

    Despite its recognized importance for cultural transmission, little is known about the role imitation plays in language learning. Three experiments examine how rates of imitation vary as a function of qualitative differences in the way language is used in a small indigenous community in Oaxaca, Mexico and three Western comparison groups. Data from…

  2. Audio Effects Based on Biorthogonal Time-Varying Frequency Warping

    Directory of Open Access Journals (Sweden)

    Cavaliere Sergio

    2001-01-01

    Full Text Available We illustrate the mathematical background and musical use of a class of audio effects based on frequency warping. These effects alter the frequency content of a signal via spectral mapping. They can be implemented in dispersive tapped delay lines based on a chain of all-pass filters. In a homogeneous line with first-order all-pass sections, the signal formed by the output samples at a given time is related to the input via the Laguerre transform. However, most musical signals require a time-varying frequency modification in order to be properly processed. Vibrato in musical instruments or voice intonation in the case of vocal sounds may be modeled as small and slow pitch variations. Simulation of these effects requires techniques for time-varying pitch and/or brightness modification that are very useful for sound processing. The basis for time-varying frequency warping is a time-varying version of the Laguerre transformation. The corresponding implementation structure is obtained as a dispersive tapped delay line, where each of the frequency dependent delay element has its own phase response. Thus, time-varying warping results in a space-varying, inhomogeneous, propagation structure. We show that time-varying frequency warping is associated to an expansion over biorthogonal sets generalizing the discrete Laguerre basis. Slow time-varying characteristics lead to slowly varying parameter sequences. The corresponding sound transformation does not suffer from discontinuities typical of delay lines based on unit delays.

  3. Expected optimal feedback with Time-Varying Parameters

    NARCIS (Netherlands)

    Tucci, M.P.; Kendrick, D.A.; Amman, H.M.

    2011-01-01

    In this paper we derive the closed loop form of the Expected Optimal Feedback rule, sometimes called passive learning stochastic control, with time varying parameters. As such this paper extends the work of Kendrick (1981,2002, Chapter 6) where parameters are assumed to vary randomly around a known

  4. Prices of Generic Heart Failure Drugs Vary Widely

    Science.gov (United States)

    ... medlineplus.gov/news/fullstory_162035.html Prices of Generic Heart Failure Drugs Vary Widely Patients can spend from $12 to $ ... Nov. 15, 2016 (HealthDay News) -- Cash prices of generic medicines to treat heart failure vary so widely that ...

  5. Analysis of time-varying psoriasis lesion image patterns

    DEFF Research Database (Denmark)

    Maletti, Gabriela Mariel; Ersbøll, Bjarne Kjær; Nielsen, Allan Aasbjerg

    2004-01-01

    The multivariate alteration detection transform is applied to pairs of within and between time varying registered psoriasis image patterns. Color band contribution to the variates explaining maximal change is analyzed.......The multivariate alteration detection transform is applied to pairs of within and between time varying registered psoriasis image patterns. Color band contribution to the variates explaining maximal change is analyzed....

  6. Linear Parameter Varying Control of Doubly Fed Induction Machines

    NARCIS (Netherlands)

    Tien, H. Nguyen; Scherer, Carsten W.; Scherpen, Jacquelien M.A.; Müller, Volkmar

    2016-01-01

    This paper is concerned with the design of a self-scheduled current controller for doubly fed induction machines. The design is based on the framework of linear parameter-varying systems where the mechanical angular speed is considered to be a measurable time-varying parameter. The objective is to o

  7. Specimen loading list for the varying temperature experiment

    Energy Technology Data Exchange (ETDEWEB)

    Qualls, A.L.; Sitterson, R.G. [Oak Ridge National Lab., TN (United States)

    1998-09-01

    The varying temperature experiment HFIR-RB-13J has been assembled and inserted in the reactor. Approximately 5300 specimens were cleaned, inspected, matched, and loaded into four specimen holders. A listing of each specimen loaded into the steady temperature holder, its position in the capsule, and the identification of the corresponding specimen loaded into the varying temperature holder is presented in this report.

  8. Analysis of distributed power control under constant and time-varying delays

    Science.gov (United States)

    Campos-delgado, Daniel U.; Luna-rivera, J. Martin; Bonilla, Isela

    2013-10-01

    This work studies the distributed power control algorithm proposed in 1993 by Foschini-Miljanic, standardised for universal mobile telecommunication systems. Continuous and discrete time versions of this algorithm are analysed. First, the stability of the distributed power allocation schemes was studied, where sufficient conditions to guarantee stability and convergence to a desired quality of service were provided. In this study, the channel gains are assumed to be slowly time-varying or piece-wise constant. For closed-loop control, a proportional controller is then employed under integral action in order to achieve good tracking despite time-varying and unknown channel gains. Next, the effects of constant and time-varying time delays in the closed-loop structure are studied. Explicit stability regions for the control gains in the Foschini-Miljanic scheme are derived for both the continuous and discrete-time versions of the algorithm, under constant and time-varying delays. For time-varying scenario, the resulting stability regions do not impose limitations on the rate change of the time-varying profiles. A comprehensive evaluation using simulations is performed to validate the analytical derivations described in the paper.

  9. Estimating time-varying conditional correlations between stock and foreign exchange markets

    Science.gov (United States)

    Tastan, Hüseyin

    2006-02-01

    This study explores the dynamic interaction between stock market returns and changes in nominal exchange rates. Many financial variables are known to exhibit fat tails and autoregressive variance structure. It is well-known that unconditional covariance and correlation coefficients also vary significantly over time and multivariate generalized autoregressive model (MGARCH) is able to capture the time-varying variance-covariance matrix for stock market returns and changes in exchange rates. The model is applied to daily Euro-Dollar exchange rates and two stock market indexes from the US economy: Dow-Jones Industrial Average Index and S&P500 Index. The news impact surfaces are also drawn based on the model estimates to see the effects of idiosyncratic shocks in respective markets.

  10. Saturn's magnetospheric refresh rate

    Science.gov (United States)

    Rymer, A. M.; Mitchell, D. G.; Hill, T. W.; Kronberg, E. A.; Krupp, N.; Jackman, C. M.

    2013-06-01

    A 2-3 day periodicity observed in Jupiter's magnetosphere (superposed on the giant planet's 9.5 h rotation rate) has been associated with a characteristic mass-loading/unloading period at Jupiter. We follow a method derived by Kronberg et al. () and find, consistent with their results, that this period is most likely to fall between 1.5 and 3.9 days. Assuming the same process operates at Saturn, we argue, based on equivalent scales at the two planets, that its period should be 4 to 6 times faster at Saturn and therefore display a period of 8 to 18 h. Applying the method of Kronberg et al. for the mass-loading source rates estimated by Smith et al. () based on data from the third and fifth Cassini-Enceladus encounters, we estimate that the expected magnetospheric refresh rate varies from 8 to 31 h, a range that includes Saturn's rotation rate of ~10.8 h. The magnetospheric period we describe is proportional to the total mass-loading rate in the system. The period is, therefore, faster (1) for increased outgassing from Enceladus, (2) near Saturn solstice (when the highest proportion of the rings is illuminated), and (3) near solar maximum when ionization by solar photons maximizes. We do not claim to explain the few percent jitter in period derived from Saturn Kilometric Radiation with this model, nor do we address the observed difference in period observed in the north and south hemispheres.

  11. H∞ Control of Four-Wheel-Independent-Drive Electric Vehicles with Random Time-Varying Delays

    Directory of Open Access Journals (Sweden)

    Gang Qin

    2015-01-01

    Full Text Available The random time-varying delays would reduce control performance and even deteriorate the EV system. To deal with random time-varying delays and achieve a real-time steady-state response, considering randomness of delay and a rapid response, an H∞-based delay-tolerant linear quadratic regulator (LQR control method based on Taylor series expansion is proposed in this paper. The results of cosimulations with Simulink and CarSim demonstrate the effectiveness of the proposed controller through the control performance of yaw rate, sideslip angle, and the running track. Moreover, the results of comparison with the other controller illustrate the strength of explicitly.

  12. Robust Stabilization of Nonlinear Systems with Uncertain Varying Control Coefficient

    Directory of Open Access Journals (Sweden)

    Zaiyue Yang

    2014-01-01

    Full Text Available This paper investigates the stabilization problem for a class of nonlinear systems, whose control coefficient is uncertain and varies continuously in value and sign. The study emphasizes the development of a robust control that consists of a modified Nussbaum function to tackle the uncertain varying control coefficient. By such a method, the finite-time escape phenomenon has been prevented when the control coefficient is crossing zero and varying its sign. The proposed control guarantees the asymptotic stabilization of the system and boundedness of all closed-loop signals. The control performance is illustrated by a numerical simulation.

  13. Impulsive control of nonlinear systems with time-varying delays

    Institute of Scientific and Technical Information of China (English)

    Yu Yong-Bin; Bao Jing-Fu; Zhang Hong-Bin; Zhong Qi-Shui; Liao Xiao-Feng; Yu Jue-Sang

    2008-01-01

    A whole impulsive control scheme of nonlinear systems with time-varying delays, which is an extension for impulsive control of nonlinear systems without time delay, is presented in this paper. Utilizing the Lyapunov functions and the impulsive-type comparison principles, we establish a series of different conditions under which impulsively controlled nonlinear systems with time-varying delays are asymptotically stable. Then we estimate upper bounds of impulse interval and time-varying delays for asymptotically stable control. Finally a numerical example is given to illustrate the effectiveness of the method.

  14. Implications of a Time-Varying Fine Structure Constant

    CERN Document Server

    Alfonso-Faus, A

    2002-01-01

    Much work has been done after the possibility of a fine structure constant being time-varying. It has been taken as an indication of a time-varying speed of light. Here we prove that this is not the case. We prove that the speed of light may or may not vary with time, independently of the fine structure constant being constant or not. Time variations of the speed of light, if present, have to be derived by some other means and not from the fine structure constant. No implications based on the possible variations of the fine structure constant can be imposed on the speed of light.

  15. TESTING FOR VARYING DISPERSION IN DISCRETE EXPONENTIAL FAMILY NONLINEAR MODELS

    Institute of Scientific and Technical Information of China (English)

    LinJinguan; WeiBocheng; ZhangNansong

    2003-01-01

    It is necessary to test for varying dispersion in generalized nonlinear models. Wei ,et al(1998) developed a likelihood ratio test,a score test and their adjustments to test for varying dispersion in continuous exponential family nonlinear models. This type of problem in the framework of general discrete exponential family nonlinear models is discussed. Two types of varying dispersion, which are random coefficients model and random effects model, are proposed,and corresponding score test statistics are constructed and expressed in simple ,easy to use ,matrix formulas.

  16. Food Allergies Among Kids Vary by Race: Study

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_162165.html Food Allergies Among Kids Vary by Race: Study Researchers find ... study of 817 children who were diagnosed with food allergies from birth to age 18, show that race ...

  17. Estimation of Time Varying Autoregressive Symmetric Alpha Stable

    Data.gov (United States)

    National Aeronautics and Space Administration — In this work, we present a novel method for modeling time-varying autoregressive impulsive signals driven by symmetric alpha stable distributions. The proposed...

  18. Comments on "Note on varying speed of light theories"

    CERN Document Server

    Magueijo, Joao

    2007-01-01

    In a recent note Ellis criticizes varying speed of light theories on the grounds of a number of foundational issues. His reflections provide us with an opportunity to clarify some fundamental matters pertaining to these theories.

  19. PERMANENCE AND PERSISTENCE OF TIME VARYING LOTKA-VOLTERRA SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this article, the permanence and persistence for three classes time varying Lotka-Volterra ecological system are investigated by using Lyapunov stability analysis and constructing the compact set of attraction. Some examples are given to illustrate the theorems.

  20. Modeling non-Gaussian time-varying vector autoregressive process

    Data.gov (United States)

    National Aeronautics and Space Administration — We present a novel and general methodology for modeling time-varying vector autoregressive processes which are widely used in many areas such as modeling of chemical...

  1. Efficient Estimation for Semiparametric Varying Coefficient Partially Linear Regression Models with Current Status Data

    Institute of Scientific and Technical Information of China (English)

    Tao Hu; Heng-jian Cui; Xing-wei Tong

    2009-01-01

    This article considers a semiparametric varying-coefficient partially linear regression model with current status data. The semiparametric varying-coefficient partially linear regression model which is a gen-eralization of the partially linear regression model and varying-coefficient regression model that allows one to explore the possibly nonlinear effect of a certain covariate on the response variable. A Sieve maximum likelihood estimation method is proposed and the asymptotic properties of the proposed estimators are discussed. Under some mild conditions, the estimators are shown to be strongly consistent. The convergence rate of the estima-tor for the unknown smooth function is obtained and the estimator for the unknown parameter is shown to be asymptotically efficient and normally distributed. Simulation studies are conducted to examine the small-sample properties of the proposed estimates and a real dataset is used to illustrate our approach.

  2. New Inference Procedures for Semiparametric Varying-Coefficient Partially Linear Cox Models

    Directory of Open Access Journals (Sweden)

    Yunbei Ma

    2014-01-01

    Full Text Available In biomedical research, one major objective is to identify risk factors and study their risk impacts, as this identification can help clinicians to both properly make a decision and increase efficiency of treatments and resource allocation. A two-step penalized-based procedure is proposed to select linear regression coefficients for linear components and to identify significant nonparametric varying-coefficient functions for semiparametric varying-coefficient partially linear Cox models. It is shown that the penalized-based resulting estimators of the linear regression coefficients are asymptotically normal and have oracle properties, and the resulting estimators of the varying-coefficient functions have optimal convergence rates. A simulation study and an empirical example are presented for illustration.

  3. Design of 2D Time-Varying Vector Fields

    KAUST Repository

    Chen, Guoning

    2012-10-01

    Design of time-varying vector fields, i.e., vector fields that can change over time, has a wide variety of important applications in computer graphics. Existing vector field design techniques do not address time-varying vector fields. In this paper, we present a framework for the design of time-varying vector fields, both for planar domains as well as manifold surfaces. Our system supports the creation and modification of various time-varying vector fields with desired spatial and temporal characteristics through several design metaphors, including streamlines, pathlines, singularity paths, and bifurcations. These design metaphors are integrated into an element-based design to generate the time-varying vector fields via a sequence of basis field summations or spatial constrained optimizations at the sampled times. The key-frame design and field deformation are also introduced to support other user design scenarios. Accordingly, a spatial-temporal constrained optimization and the time-varying transformation are employed to generate the desired fields for these two design scenarios, respectively. We apply the time-varying vector fields generated using our design system to a number of important computer graphics applications that require controllable dynamic effects, such as evolving surface appearance, dynamic scene design, steerable crowd movement, and painterly animation. Many of these are difficult or impossible to achieve via prior simulation-based methods. In these applications, the time-varying vector fields have been applied as either orientation fields or advection fields to control the instantaneous appearance or evolving trajectories of the dynamic effects. © 1995-2012 IEEE.

  4. Model Identification of Linear Parameter Varying Aircraft Systems

    OpenAIRE

    Fujimore, Atsushi; Ljung, Lennart

    2007-01-01

    This article presents a parameter estimation of continuous-time polytopic models for a linear parameter varying (LPV) system. The prediction error method of linear time invariant (LTI) models is modified for polytopic models. The modified prediction error method is applied to an LPV aircraft system whose varying parameter is the flight velocity and model parameters are the stability and control derivatives (SCDs). In an identification simulation, the polytopic model is more suitable for expre...

  5. Do Time-Varying Covariances, Volatility Comovement and Spillover Matter?

    OpenAIRE

    Lakshmi Balasubramanyan

    2005-01-01

    Financial markets and their respective assets are so intertwined; analyzing any single market in isolation ignores important information. We investigate whether time varying volatility comovement and spillover impact the true variance-covariance matrix under a time-varying correlation set up. Statistically significant volatility spillover and comovement between US, UK and Japan is found. To demonstrate the importance of modelling volatility comovement and spillover, we look at a simple portfo...

  6. GPU Acceleration of Image Convolution using Spatially-varying Kernel

    OpenAIRE

    Hartung, Steven; Shukla, Hemant; Miller, J. Patrick; Pennypacker, Carlton

    2012-01-01

    Image subtraction in astronomy is a tool for transient object discovery such as asteroids, extra-solar planets and supernovae. To match point spread functions (PSFs) between images of the same field taken at different times a convolution technique is used. Particularly suitable for large-scale images is a computationally intensive spatially-varying kernel. The underlying algorithm is inherently massively parallel due to unique kernel generation at every pixel location. The spatially-varying k...

  7. Trill performance components vary with age, season, and motivation in the banded wren.

    Science.gov (United States)

    Vehrencamp, S L; Yantachka, J; Hall, M L; de Kort, S R

    2013-03-01

    Acoustic displays with difficult-to-execute sounds are often subject to strong sexual selection, because performance levels are related to the sender's condition or genetic quality. Performance may also vary with age, breeding stage, and motivation related to social context. We focused on within-male variation in four components of trill performance in banded wren (Thryophilus pleurostictus) songs: note consistency, frequency bandwidth, note rate and vocal deviation. The latter is a composite measure reflecting deviation from the performance limit on simultaneously maximizing both frequency bandwidth and note rate. We compared the changes in these song parameters at three time scales: over the course of years, across the breeding season, and at different times of the day with contrasting agonistic contexts. Vocal deviation decreased and note consistency increased over years, suggesting that experience may improve individual proficiency at singing trills. Consistency also increased across the season, confirming that practice is important for this parameter. Although there was no significant seasonal change in vocal deviation, one of its components, note rate, increased during the season. Neither vocal deviation nor consistency varied with agonistic context. However, note rate increased during playback experiments simulating territorial intrusions compared to dawn chorus singing. The magnitude of a male's increase in note rate was positively correlated with his aggressive behavior during the playback experiment. Thus consistency, bandwidth, and vocal deviation indicate age, whereas trill rate flexibly indicates the singer's aggressive motivation. We also found evidence of a within-male trade-off between vocal deviation and consistency.

  8. Frequency-domain L2-stability conditions for time-varying linear and nonlinear MIMO systems

    Institute of Scientific and Technical Information of China (English)

    Zhihong HUANG; Y. V. VENKATESH; Cheng XIANG; Tong Heng LEE

    2014-01-01

    The paper deals with the L2-stability analysis of multi-input-multi-output (MIMO) systems, governed by integral equations, with a matrix of periodic/aperiodic time-varying gains and a vector of monotone, non-monotone and quasi-monotone nonlin-earities. For nonlinear MIMO systems that are described by differential equations, most of the literature on stability is based on an application of quadratic forms as Lyapunov-function candidates. In contrast, a non-Lyapunov framework is employed here to derive new and more general L2-stability conditions in the frequency domain. These conditions have the following features:i) They are expressed in terms of the positive definiteness of the real part of matrices involving the transfer function of the linear time-invariant block and a matrix multiplier function that incorporates the minimax properties of the time-varying linear/nonlinear block. ii) For certain cases of the periodic time-varying gain, they contain, depending on the multiplier function chosen, no restrictions on the normalized rate of variation of the time-varying gain, but, for other periodic/aperiodic time-varying gains, they do. Overall, even when specialized to periodic-coefficient linear and nonlinear MIMO systems, the stability conditions are distinct from and less restrictive than recent results in the literature. No comparable results exist in the literature for aperiodic time-varying gains. Furthermore, some new stability results concerning the dwell-time problem and time-varying gain switching in linear and nonlinear MIMO systems with periodic/aperiodic matrix gains are also presented. Examples are given to illustrate a few of the stability theorems.

  9. Titanium (IV) sol-gel chemistry in varied gravity environments

    Science.gov (United States)

    Hales, Matthew; Martens, Wayde; Steinberg, Theodore

    Sol-gel synthesis in reduced gravity is a relatively new topic in the literature and further inves-tigation is essential to realise its potential and application to other sol-gel systems. The sol-gel technique has been successfully applied to the synthesis of silica systems of varying porosity for many diverse applications [1-5]. It is proposed that current methods for the synthesis of silica sol-gels in reduced gravity may be applied to titanium sol-gel processing in order to enhance desirable physical and chemical characteristics of the final materials. The physical and chemical formation mechanisms for titanium alkoxide based sol-gels, to date, is not fully understood. However, various authors [6-9] have described potential methods to control the hydrolysis and condensation reactions of titanium alkoxides through the use of chemical inhibitors. A preliminary study of the reaction kinetics of titanium alkoxide sol-gel reaction in normal gravity was undertaken in order to determine reactant mixtures suitable for further testing under varied gravity conditions of limited duration. Through the use of 1H Nuclear Magnetic Resonance spectroscopy (NMR) for structural analysis of precursor materials, Ultra-Violet-Visible spectroscopy (UV-VIS) and viscosity measurements, it was demonstrated that not only could the rate of the chemical reaction could be controlled, but directed linear chain growth within the resulting gel structure was achievable through the use of increased inhibitor concentrations. Two unique test systems have been fabricated to study the effects of varied gravity (reduced, normal, high) on the formation of titanium sol-gels. Whilst the first system is to be used in conjunction with the recently commissioned drop tower facility at Queensland University of Technology in Brisbane, Australia to produce reduced gravity conditions. The second system is a centrifuge capable of providing high gravity environments of up to 70 G's for extended periods of time

  10. Volitional components of consciousness vary across wakefulness, dreaming, and lucid dreaming

    OpenAIRE

    Martin eDresler; Leandra eEibl; Christian FJ Fischer; Renate eWehrle; Spoormaker, Victor I.; Axel eSteiger; Michael eCzisch; Marcel ePawlowski

    2014-01-01

    Consciousness is a multifaceted concept; its different aspects vary across species, vigilance states, or health conditions. While basal aspects of consciousness like perceptions and emotions are present in many states and species, higher-order aspects like reflective or volitional capabilities seem to be most pronounced in awake humans. Here we assess the experience of volition across different states of consciousness: 10 frequent lucid dreamers rated different aspects of volition according t...

  11. A hepatitis C virus infection model with time-varying drug effectiveness: solution and analysis.

    Directory of Open Access Journals (Sweden)

    Jessica M Conway

    2014-08-01

    Full Text Available Simple models of therapy for viral diseases such as hepatitis C virus (HCV or human immunodeficiency virus assume that, once therapy is started, the drug has a constant effectiveness. More realistic models have assumed either that the drug effectiveness depends on the drug concentration or that the effectiveness varies over time. Here a previously introduced varying-effectiveness (VE model is studied mathematically in the context of HCV infection. We show that while the model is linear, it has no closed-form solution due to the time-varying nature of the effectiveness. We then show that the model can be transformed into a Bessel equation and derive an analytic solution in terms of modified Bessel functions, which are defined as infinite series, with time-varying arguments. Fitting the solution to data from HCV infected patients under therapy has yielded values for the parameters in the model. We show that for biologically realistic parameters, the predicted viral decay on therapy is generally biphasic and resembles that predicted by constant-effectiveness (CE models. We introduce a general method for determining the time at which the transition between decay phases occurs based on calculating the point of maximum curvature of the viral decay curve. For the parameter regimes of interest, we also find approximate solutions for the VE model and establish the asymptotic behavior of the system. We show that the rate of second phase decay is determined by the death rate of infected cells multiplied by the maximum effectiveness of therapy, whereas the rate of first phase decline depends on multiple parameters including the rate of increase of drug effectiveness with time.

  12. Globalization And Time Varying Prices Of Market And Foreign Exchange Risks: Canadian Evidence

    OpenAIRE

    Sarath Abeysekera; Sergiy Rakhmayil

    2011-01-01

    The paper empirically examines the relationship between stock returns, exchange rate, and market risks for the Canadian stock market operating in an increasingly global environment. Time varying prices of market and currency risks and corresponding risk premia are estimated. We investigate how estimated risk premia in different industry sectors are affected by macroeconomic events associated with globalization. We find that magnitude of shocks is greater, and risk premia at the times of econo...

  13. Variable Selection for Varying-Coefficient Models with Missing Response at Random

    Institute of Scientific and Technical Information of China (English)

    Pei Xin ZHAO; Liu Gen XUE

    2011-01-01

    In this paper, we present a variable selection procedure by combining basis function approximations with penalized estimating equations for varying-coefficient models with missing response at random. With appropriate selection of the tuning parameters, we establish the consistency of the variable selection procedure and the optimal convergence rate of the regularized estimators. A simulation study is undertaken to assess the finite sample performance of the proposed variable selection procedure.

  14. Dynamic Behaviors of Axially Moving Viscoelastic Plate with Varying Thicknessn

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yinfeng; WANG Zhongmin

    2009-01-01

    Structural components of varying thickness draw increasing attention these days due to economy and light-weight considerations. In view of the absence of research in vibration analysis of viscoelastic plate with varying thickness, this study devotes to investigate the dynamic behaviors of axially moving viscoelastic plate with varying thickness. Based on the thin plate theory and the two-dimensional viscoelastic differential constitutive relation, the differential equation of motion of the axially moving viscoelastic rectangular plate is derived, the plate constituted by Kelvin-Voigt model has linearly varying thickness in the y-direction. The dimensionless complex frequencies of axially moving viscoelastic plate with four edges simply supported are calculated by the differential quadrature method, curves of real parts and imaginary parts of the first three-order dimensionless complex frequencies versus dimensionless moving speed are obtained, the effects of the aspect ratio, thickness ratio, the dimensionless moving speed and delay time on the dynamic behaviors of the axially moving viscoelastic rectangular plate with varying thickness are analyzed. When other parameters keep constant, with the decrease of thickness ratio, the real parts of the first three-order natural frequencies decrease, and the critical divergence speeds of various modes decrease too, moreover, whether the delay time is large or small, the frequencies are all complex numbers.

  15. Linear, Parameter-Varying Control of Aeroservoelastic Systems

    Science.gov (United States)

    Moreno Chicunque, Claudia Patricia

    Modern aircraft designers are adopting light-weight, high-aspect ratio flexible wings to improve performance and reduce operation costs. A technical challenge associated with these designs is that the large deformations in flight of the wings lead to adverse interactions between the aircraft aerodynamic forces and structural forces. These adverse interactions produce excessive vibrations that can degrade flying qualities and may result in severe structural damages or catastrophic failure. This dissertation is focused on the application of multivariable robust control techniques for suppression of these adverse interactions in flexible aircraft. Here, the aircraft coupled nonlinear equations of motion are represented in the linear, parameter-varying framework. These equations account for the coupled aerodynamics, rigid body dynamics, and deformable body dynamics of the aircraft. Unfortunately, the inclusion of this coupled dynamics results in high-order models that increase the computational complexity of linear, parameter-varying control techniques. This dissertation addresses three key technologies for linear, parameter-varying control of flexible aircraft: (i) linear, parameter-varying model reduction; (ii) selection of actuators and sensors for vibration suppression; and (iii) design of linear, parameter-varying controllers for vibration suppression. All of these three technologies are applied to an experimental research platform located at the University of Minnesota. The objective of this dissertation is to provide to the flight control community with a set of design methodologies to safely exploit the benefits of light-weight flexible aircraft.

  16. Time-varying Reeb Graphs: A Topological Framework Supporting the Analysis of Continuous Time-varying Data

    Energy Technology Data Exchange (ETDEWEB)

    Mascarenhas, Ajith Arthur [Univ. of North Carolina, Chapel Hill, NC (United States)

    2006-01-01

    I present time-varying Reeb graphs as a topological framework to support the analysis of continuous time-varying data. Such data is captured in many studies, including computational fluid dynamics, oceanography, medical imaging, and climate modeling, by measuring physical processes over time, or by modeling and simulating them on a computer. Analysis tools are applied to these data sets by scientists and engineers who seek to understand the underlying physical processes. A popular tool for analyzing scientific datasets is level sets, which are the points in space with a fixed data value s. Displaying level sets allows the user to study their geometry, their topological features such as connected components, handles, and voids, and to study the evolution of these features for varying s. For static data, the Reeb graph encodes the evolution of topological features and compactly represents topological information of all level sets. The Reeb graph essentially contracts each level set component to a point. It can be computed efficiently, and it has several uses: as a succinct summary of the data, as an interface to select meaningful level sets, as a data structure to accelerate level set extraction, and as a guide to remove noise. I extend these uses of Reeb graphs to time-varying data. I characterize the changes to Reeb graphs over time, and develop an algorithm that can maintain a Reeb graph data structure by tracking these changes over time. I store this sequence of Reeb graphs compactly, and call it a time-varying Reeb graph. I augment the time-varying Reeb graph with information that records the topology of level sets of all level values at all times, that maintains the correspondence of level set components over time, and that accelerates the extraction of level sets for a chosen level value and time. Scientific data sampled in space-time must be extended everywhere in this domain using an interpolant. A poor choice of interpolant can create degeneracies that are

  17. Climate and hillslope degradation vary in concert; 85 ka to present, eastern Sierra Nevada, CA, USA

    Science.gov (United States)

    Madoff, Risa D.; Putkonen, Jaakko

    2016-08-01

    Degradation in the landscape results when the interactions of climate, substrate, and biota dislodge and transport sediment that is mantling landforms. Rates of degradation through time control landform stability and resiliency. Therefore, records of past degradation rates can be used to inform us on how a given landscape responded to significant changes in past climates. For example, climate has varied at many temporal scales, and some of the largest recent shifts enabled the glacial advances and retreats in time scales of 20-100 ka. Therefore, it is reasonable to expect that the rate of landscape degradation has also varied at similar time scales. However, the general hillslope diffusion equation that is commonly used to model cross-profiles of hillslopes on time scales of thousands to tens of thousands of years typically relies on a constant and optimized rate parameter to generate a model cross-profile approximating the current observed landform cross-profile. Using a time-varying diffusivity parameter, we generated three separate degradation scenarios for the Mono Basin moraine in the eastern Sierra Nevada, CA, USA, in order to assess the potential impact of varying past climates on sediment transport. We used published paleoclimate records in the study area and modern rates of surface degradation from climates that correspond broadly to those paleoclimates. The results indicate that, in this case, the climate driven and, therefore, time-dependent degradation model produces a good fit between the modeled and observed landform profiles. Results showed that, when the surface elevations of the reference case (constant optimized diffusivity) were compared through time to the surface elevations of the time-dependent model, the differences were relatively small. The largest deviation was found to occur during the Last Glacial Maximum (LGM). We found that for investigations into the geological effects of climate change in glacial and polar regions, the use of time-varying

  18. Correction of spatially varying image and video motion blur using a hybrid camera.

    Science.gov (United States)

    Tai, Yu-Wing; Du, Hao; Brown, Michael S; Lin, Stephen

    2010-06-01

    We describe a novel approach to reduce spatially varying motion blur in video and images using a hybrid camera system. A hybrid camera is a standard video camera that is coupled with an auxiliary low-resolution camera sharing the same optical path but capturing at a significantly higher frame rate. The auxiliary video is temporally sharper but at a lower resolution, while the lower frame-rate video has higher spatial resolution but is susceptible to motion blur. Our deblurring approach uses the data from these two video streams to reduce spatially varying motion blur in the high-resolution camera with a technique that combines both deconvolution and super-resolution. Our algorithm also incorporates a refinement of the spatially varying blur kernels to further improve results. Our approach can reduce motion blur from the high-resolution video as well as estimate new high-resolution frames at a higher frame rate. Experimental results on a variety of inputs demonstrate notable improvement over current state-of-the-art methods in image/video deblurring.

  19. Staffing of Time-Varying Queues to Achieve Time-Stable Performance

    OpenAIRE

    Zohar Feldman; Avishai Mandelbaum; William A. Massey; Ward Whitt

    2008-01-01

    This paper develops methods to determine appropriate staffing levels in call centers and other many-server queueing systems with time-varying arrival rates. The goal is to achieve targeted time-stable performance, even in the presence of significant time variation in the arrival rates. The main contribution is a flexible simulation-based iterative-staffing algorithm (ISA) for the M t /G/s t + G model--with nonhomogeneous Poisson arrival process (the M t ) and customer abandonment (the + G). F...

  20. Robust linear parameter varying induction motor control with polytopic models

    Directory of Open Access Journals (Sweden)

    Dalila Khamari

    2013-01-01

    Full Text Available This paper deals with a robust controller for an induction motor which is represented as a linear parameter varying systems. To do so linear matrix inequality (LMI based approach and robust Lyapunov feedback controller are associated. This new approach is related to the fact that the synthesis of a linear parameter varying (LPV feedback controller for the inner loop take into account rotor resistance and mechanical speed as varying parameter. An LPV flux observer is also synthesized to estimate rotor flux providing reference to cited above regulator. The induction motor is described as a polytopic model because of speed and rotor resistance affine dependence their values can be estimated on line during systems operations. The simulation results are presented to confirm the effectiveness of the proposed approach where robustness stability and high performances have been achieved over the entire operating range of the induction motor.

  1. Synchronization of networks with time-varying couplings

    Institute of Scientific and Technical Information of China (English)

    LU Wen-lian; CHEN Tian-ping

    2013-01-01

    In this paper, we present a review of our recent works on complete synchro-nization analyses of networks of the coupled dynamical systems with time-varying cou-plings. The main approach is composed of algebraic graph theory and dynamic system method. More precisely, the Hajnal diameter of matrix sequence plays a key role in in-vestigating synchronization dynamics and the joint graph across time periods possessing spanning tree is a doorsill for time-varying topologies to reach synchronization. These techniques with proper modification count for diverse models of networks of the cou-pled systems, including discrete-time and continuous-time models, linear and nonlinear models, deterministic and stochastic time-variations. Alternatively, transverse stability analysis of general time-varying dynamic systems can be employed for synchronization study as a special case and proved to be equivalent to Hajnal diameter.

  2. Time varying networks and the weakness of strong ties

    Science.gov (United States)

    Karsai, Márton; Perra, Nicola; Vespignani, Alessandro

    2014-02-01

    In most social and information systems the activity of agents generates rapidly evolving time-varying networks. The temporal variation in networks' connectivity patterns and the ongoing dynamic processes are usually coupled in ways that still challenge our mathematical or computational modelling. Here we analyse a mobile call dataset and find a simple statistical law that characterize the temporal evolution of users' egocentric networks. We encode this observation in a reinforcement process defining a time-varying network model that exhibits the emergence of strong and weak ties. We study the effect of time-varying and heterogeneous interactions on the classic rumour spreading model in both synthetic, and real-world networks. We observe that strong ties severely inhibit information diffusion by confining the spreading process among agents with recurrent communication patterns. This provides the counterintuitive evidence that strong ties may have a negative role in the spreading of information across networks.

  3. Photon propagation in slowly varying inhomogeneous electromagnetic fields

    CERN Document Server

    Karbstein, Felix

    2015-01-01

    Starting from the Heisenberg-Euler effective Lagrangian, we determine the photon current and photon polarization tensor in inhomogeneous, slowly varying electromagnetic fields. To this end, we consider background field configurations varying in both space and time, paying special attention to the tensor structure. As a main result, we obtain compact analytical expressions for the photon polarization tensor in realistic Gaussian laser pulses, as generated in the focal spots of high-intensity lasers. These expressions are of utmost importance for the investigation of quantum vacuum nonlinearities in realistic high-intensity laser experiments.

  4. Comparative Analysis of Instruments Measuring Time Varying Harmonics

    Science.gov (United States)

    Belchior, Fernando Nunes; Ribeiro, Paulo Fernando; Carvalho, Frederico Marques

    2016-08-01

    This paper aims to evaluate the performance of commercial class A and class S power quality (PQ) instruments when measuring time-varying harmonics. By using a high precision programmable voltage and current source, two meters from different manufacturers are analyzed and compared. Three-phase voltage signals are applied to PQ instruments, considering 3 situations of time-varying harmonic distortions, whose harmonic distortion values are in accordance with typical values found in power systems. This work is relevant considering that international standardization documents do not pay much attention to this aspect of harmonic distortion.

  5. Cosmological models with interacting components and mass-varying neutrinos

    CERN Document Server

    Collodel, Lucas G

    2012-01-01

    A model for a homogeneous and isotropic spatially flat Universe, composed of baryons, radiation, neutrinos, dark matter and dark energy is analyzed. We infer that dark energy (considered to behave as a scalar field) interacts with dark matter (either by the Wetterich model, or by the Anderson and Carroll model) and with neutrinos by a model proposed by Brookfield et al.. The latter is understood to have a mass-varying behavior. We show that for a very-softly varying field, both interacting models for dark matter give the same results. The models reproduce the expected red-shift performances of the present behavior of the Universe.

  6. Partially linear varying coefficient models stratified by a functional covariate

    KAUST Repository

    Maity, Arnab

    2012-10-01

    We consider the problem of estimation in semiparametric varying coefficient models where the covariate modifying the varying coefficients is functional and is modeled nonparametrically. We develop a kernel-based estimator of the nonparametric component and a profiling estimator of the parametric component of the model and derive their asymptotic properties. Specifically, we show the consistency of the nonparametric functional estimates and derive the asymptotic expansion of the estimates of the parametric component. We illustrate the performance of our methodology using a simulation study and a real data application.

  7. Mass varying neutrinos, symmetry breaking, and cosmic acceleration

    Science.gov (United States)

    Sadjadi, H. Mohseni; Anari, V.

    2017-06-01

    We introduce a new proposal for the onset of cosmic acceleration based on mass varying neutrinos. When massive neutrinos become nonrelativistic, the Z2 symmetry breaks, and the quintessence potential becomes positive from its initially zero value. This positive potential behaves like a cosmological constant at the present era and drives the Universe's acceleration during the slow roll evolution of the quintessence. In contrast to Λ CDM model, the dark energy in our model is dynamical, and the acceleration is not persistent. Contrary to some of the previous models of dark energy with mass varying neutrinos, we do not use the adiabaticity condition, which leads to instability.

  8. Nonstationary Feller process with time-varying coefficients

    Science.gov (United States)

    Masoliver, Jaume

    2016-01-01

    We study the nonstationary Feller process with time varying coefficients. We obtain the exact probability distribution exemplified by its characteristic function and cumulants. In some particular cases we exactly invert the distribution and achieve the probability density function. We show that for sufficiently long times this density approaches a Γ distribution with time-varying shape and scale parameters. Not far from the origin the process obeys a power law with an exponent dependent of time, thereby concluding that accessibility to the origin is not static but dynamic. We finally discuss some possible applications of the process.

  9. Climatic response to a time varying solar constant

    Science.gov (United States)

    North, G. R.; Short, D. A.; Mengel, J. G.

    1983-01-01

    Recent measurements of the solar constant, theoretical arguments, and climatic measurements combined with signal processing suggest the possibility that the solar constant varies significantly on time scales ranging from billions of years to 11-yr (sunspot) cycles, and even to scales of a few weeks. Simple climate models with a time varying solar constant are examined here, with emphasis on the heat balance models (North et al., 1981). Linear heat balance model results are presented for high (10 cycles/yr) and low (0.1 cycle/yr) frequencies, providing a useful guide in estimating the direct heat response to solar variability.

  10. Stability interval for time-varying delay systems

    OpenAIRE

    Ariba, Yassine; Gouaisbaut, F.; Johansson, Karl Henrik

    2010-01-01

    We investigate the stability analysis of linear time-delay systems. The time-delay is assumed to be a time-varying continuous function belonging to an interval (possibly excluding zero) with a bound on its derivative. To this end, we propose to use the quadratic separation framework to assess the intervals on the delay that preserves the stability. Nevertheless, to take the time-varying nature of the delay into account, the quadratic separation principle has to be extended to cope with the ge...

  11. On the existence of stable seasonally varying Arctic sea ice

    CERN Document Server

    Moon, W

    2012-01-01

    Within the framework lower order thermodynamic theories for the climatic evolution of Arctic sea ice we isolate the conditions required for the existence of stable seasonally-varying ice states. This is done by constructing a two-season model from the continuously evolving theory of Eisenman and Wettlaufer (2009) and showing that the necessary and sufficient condition for stable seasonally-varying states resides in the relaxation of the constant annual average short-wave radiative forcing. This forcing is examined within the scenario of greenhouse gas warming, as a function of which stability conditions are discerned.

  12. Free vibration analysis of Mindlin plates with linearly varying thickness

    Science.gov (United States)

    Aksu, G.; Al-Kaabi, S. A.

    1987-12-01

    A method based on the variational principles in conjunction with the finite difference technique is applied to examine the free vibration characteristics of isotropic rectangular plates of linearly varying thickness by including the effects of transverse shear deformation and rotary inertia. The validity of the present approach is demonstrated by comparing the results with other solutions proposed for plates with uniform and linearly varying thickness. Natural frequencies and mode shapes of Mindlin plates with simply supported and clamped edges are determined for various values of relative thickness ratio and the taper thickness constant.

  13. Partially Linear Varying Coefficient Models Stratified by a Functional Covariate.

    Science.gov (United States)

    Maity, Arnab; Huang, Jianhua Z

    2012-10-01

    We consider the problem of estimation in semiparametric varying coefficient models where the covariate modifying the varying coefficients is functional and is modeled nonparametrically. We develop a kernel-based estimator of the nonparametric component and a profiling estimator of the parametric component of the model and derive their asymptotic properties. Specifically, we show the consistency of the nonparametric functional estimates and derive the asymptotic expansion of the estimates of the parametric component. We illustrate the performance of our methodology using a simulation study and a real data application.

  14. Harbour porpoise distribution can vary at small spatiotemporal scales in energetic habitats

    Science.gov (United States)

    Benjamins, Steven; van Geel, Nienke; Hastie, Gordon; Elliott, Jim; Wilson, Ben

    2017-07-01

    Marine habitat heterogeneity underpins species distribution and can be generated through interactions between physical and biological drivers at multiple spatiotemporal scales. Passive acoustic monitoring (PAM) is used worldwide to study potential impacts of marine industrial activities on cetaceans, but understanding of animals' site use at small spatiotemporal scales (test site (the European Marine Energy Centre [Billia Croo, Orkney]) and by a minor tidal-stream site (Scarba [Inner Hebrides]). Respective arrays consisted of 7 and 11 moorings containing two C-PODs each and were deployed for up to 55 days. Minimum inter-mooring distances varied between 300-600 m. All C-POD data were analysed at a temporal resolution of whole minutes, with each minute classified as 1 or 0 on the basis of presence/absence of porpoise click trains (Porpoise-Positive Minutes/PPMs). Porpoise detection rates were analysed using Generalised Additive Models (GAMs) with Generalised Estimation Equations (GEEs). Although there were many porpoise detections (wave test site: N=3,432; tidal-stream site: N=17,366), daily detection rates varied significantly within both arrays. Within the wave site array (<1 km diameter), average daily detection rates varied from 4.3 to 14.8 PPMs/day. Within the tidal-stream array (<2 km diameter), average daily detection rates varied from 10.3 to 49.7 PPMs/day. GAM-GEE model results for individual moorings within both arrays indicated linkages between porpoise presence and small-scale heterogeneity among different environmental covariates (e.g., tidal phase, time of day). Porpoise detection rates varied considerably but with coherent patterns between moorings only several hundred metres apart and within hours. These patterns presumably have ecological relevance. These results indicate that, in energetically active and heterogeneous areas, porpoises can display significant spatiotemporal variability in site use at scales of hundreds of metres and hours. Such

  15. Time Varying Market Integration and Expected Rteurns in Emerging Markets

    NARCIS (Netherlands)

    de Jong, F.C.J.M.; de Roon, F.A.

    2001-01-01

    We use a simple model in which the expected returns in emerging markets depend on their systematic risk as measured by their beta relative to the world portfolio as well as on the level of integration in that market.The level of integration is a time-varying variable that depends on the market value

  16. Varactor Modelling for Power Factor Correction in a Varying Load

    Directory of Open Access Journals (Sweden)

    Agwu D. D.

    2016-06-01

    Full Text Available : For efficient system operation, it is desirable to keep the power factor at, or very close to unity. One of the very often used methods is application of suitable power factor correction technology. Capacitors are good candidate for constant load power factor correction due to suitability and cost effectiveness. However for varying loads, synchronous condensers are preferred despite having high initial cost as a result of their being able to supply varying leading or lagging reactive power; according to their field excitation. Due to the high acquisition and operation cost of synchronous condensers, this paper presents varactors as a possible alternative for power factor correction. These are diodes that vary their capacitances and leading reactive power according to supply voltage. Applying this involves looking at variation of power factor with supply voltage; and the option of aggregating and harnessing the junction capacitance of varactors for power factor correction of varying loads at low voltage AC levels. This innovation may lead to great improvement in distribution systems requiring quality power supply

  17. Time varying market efficiency of the GCC stock markets

    Science.gov (United States)

    Charfeddine, Lanouar; Khediri, Karim Ben

    2016-02-01

    This paper investigates the time-varying levels of weak-form market efficiency for the GCC stock markets over the period spanning from May 2005 to September 2013. We use two empirical approaches: (1) the generalized autoregressive conditional heteroscedasticity in mean (GARCH-M) model with state space time varying parameter (Kalman filter), and (2) a rolling technique sample test of the fractional long memory parameter d. As long memory estimation methods, we use the detrended fluctuation analysis (DFA) technique, the modified R/S statistic, the exact local whittle (ELW) and the feasible Exact Local Whittle (FELW) methods. Moreover, we use the Bai and Perron (1998, 2003) multiple structural breaks technique to test and date the time varying behavior of stock market efficiency. Empirical results show that GCC markets have different degrees of time-varying efficiency, and also have experiencing periods of efficiency improvement. Results also show evidence of structural breaks in all GCC markets. Moreover, we observe that the recent financial shocks such as Arab spring and subprime crises have a significant impact on the time path evolution of market efficiency.

  18. modelling flow over stepped spillway with varying chute geometry

    African Journals Online (AJOL)

    2012-07-02

    Jul 2, 2012 ... to obtain some varying flow data in 36 different experiments. These obtained flow ... The percentage difference between the values predicted by each of these ..... d1 the discharge per unit width q, gravity accelera- tion g, and ...

  19. Graduate Students' Pay and Benefits Vary Widely, Survey Shows

    Science.gov (United States)

    June, Audrey Williams

    2008-01-01

    Graduate students face an array of choices when evaluating compensation-and-benefits packages that make comparisons difficult. A "Chronicle" survey shows that the offers to teaching assistants and research assistants vary widely. Some institutions cover 100 percent of graduate students' tuition, while others waive only a portion. It is possible to…

  20. A New Parametrization of Mass Varying Neutrinos Applied in Supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Rossi-Torres, F.; Guzzo, M.M.; Holanda, P.C. de; Peres, O.L.G. [Instituto de Fisica Gleb Wataghin - UNICAMP, Rua Sergio Buarque de Holanda, 777, 13083-859, Campinas-SP (Brazil)

    2012-08-15

    We propose a phenomenological model of mass varying neutrino (MaVaN) to be applied to supernovae. We consider oscillations of {nu}{sup Macron }{sub e}{yields}{nu}{sup Macron }{sub s} in this MaVaN approach and seek for possible modifications of survival probabilities.

  1. Time-Varying FOPDT System Identification with Unknown Disturbance Input

    DEFF Research Database (Denmark)

    Sun, Zhen; Yang, Zhenyu

    2012-01-01

    The Time-Varying First Order Plus Dead Time (TV-FOPDT) model is an extension of the conventional FOPDT by allowing the system parameters, which are primarily defined on the transfer function description, i.e., the DC-gain, time constant and time delay, to be time dependent. The TV-FOPDT identific...

  2. Incremental Closed-loop Identification of Linear Parameter Varying Systems

    DEFF Research Database (Denmark)

    Bendtsen, Jan Dimon; Trangbæk, Klaus

    2011-01-01

    This paper deals with system identification for control of linear parameter varying systems. In practical applications, it is often important to be able to identify small plant changes in an incremental manner without shutting down the system and/or disconnecting the controller; unfortunately, cl...

  3. Time-varying Combinations of Predictive Densities using Nonlinear Filtering

    NARCIS (Netherlands)

    M. Billio (Monica); R. Casarin (Roberto); F. Ravazzolo (Francesco); H.K. van Dijk (Herman)

    2012-01-01

    textabstractWe propose a Bayesian combination approach for multivariate predictive densities which relies upon a distributional state space representation of the combination weights. Several specifications of multivariate time-varying weights are introduced with a particular focus on weight dynamics

  4. Karlovy Varys linastub kaks Eesti filmi / Andris Feldmanis

    Index Scriptorium Estoniae

    Feldmanis, Andris, 1982-

    2007-01-01

    Ilmar Raagi mängufilm "Klass" osaleb 42. Karlovy Vary rahvusvahelise filmifestivali võistlusprogrammis "East of the West" ja Asko Kase lühimängufilm "Zen läbi prügi" on valitud festivali kõrvalprogrammi "Forum of Independents"

  5. A Darboux-type theorem for slowly varying functions

    NARCIS (Netherlands)

    Braaksma, BLJ; Stark, D

    1997-01-01

    For functions g(z) satisfying a slowly varying condition in the complex plane, we iind asymptotics For the Taylor coefficients of the function f(z) = g(z)(1-z)(-alpha) when alpha > 0. As applications we find asymptotics for the number of permutations with cycle lengths all lying in a given set S, an

  6. Excessive infant crying: The impact of varying definitions

    NARCIS (Netherlands)

    Reijneveld, S.A.; Brugman, E.; Hirasing, R.A.

    2001-01-01

    Objective. To assess the impact of varying definitions of excessive crying and infantile colic on prevalence estimates and to assess to what extent these definitions comprise the same children. Methods. Parents of 3345 infants aged 1, 3, and 6 months (response: 96.5%) were interviewed on the crying

  7. Excessive infant crying : The impact of varying definitions

    NARCIS (Netherlands)

    Reijneveld, SA; Brugman, E; Hirasing, RA

    2001-01-01

    Objective. To assess the impact of varying definitions of excessive crying and infantile colic on prevalence estimates and to assess to what extent these definitions comprise the same children. Methods. Parents of 3345 infants aged 1, 3, and 6 months (response: 96.5%) were interviewed on the crying

  8. Adolescent Sexual Behaviors at Varying Levels of Substance Use Frequency

    Science.gov (United States)

    Floyd, Leah J.; Latimer, William

    2010-01-01

    Combining substance use and sex compounds the risk of contracting sexually transmitted diseases, including HIV. However, the association between substance use and sexual behaviors may vary by substance and sexual behavior. The current study sought to examine the relationship between alcohol and marijuana use frequency and specific sexual…

  9. Time-Varying Triplet State Lifetimes of Single Molecules

    NARCIS (Netherlands)

    Veerman, J.A.; Garcia-Parajo, M.F.; Kuipers, L.; Hulst, van N.F.

    1999-01-01

    It is found that triplet state lifetimes and intersystem crossing yields of individual molecules embedded in a polymer host at room temperature are not constant in time. The range over which the triplet lifetime of a single molecule varies during long observation times shows a strong similarity with

  10. Cosmology with a time-varying speed of light

    CERN Document Server

    Albrecht, Andreas

    1999-01-01

    Cosmic inflation is the only known mechanism with the potential to explain the very special initial conditions which are required at the early stages of the evolution of our universe. This article outlines my work with Joao Magueijo which attempts to construct an alternative mechanism based on a time-varying speed of light.

  11. Cosmology with a time-varying speed of light

    Science.gov (United States)

    Albrecht, Andreas

    1999-07-01

    Cosmic inflation is the only known mechanism with the potential to explain the very special initial conditions which are required at the early stages of the evolution of our universe. This article outlines my work with Joao Magueijo which attempts to construct an alternative mechanism based on a time-varying speed of light.

  12. Time-Varying Affective Response for Humanoid Robots

    Science.gov (United States)

    Moshkina, Lilia; Arkin, Ronald C.; Lee, Jamee K.; Jung, Hyunryong

    This paper describes the design of a complex time-varying affective architecture. It is an expansion of the TAME architecture (traits, attitudes, moods, and emotions) as applied to humanoid robotics. It particular it is intended to promote effective human-robot interaction by conveying the robot’s affective state to the user in an easy-to-interpret manner.

  13. Optimisation of vehicle passive safety for occupants with varying anthropometry

    NARCIS (Netherlands)

    Happee, R.; Haaster, R. van; Michaelsen, L.; Hoffmann, R.

    1998-01-01

    A method has been devloped to generate models representing subjects of varying anthropometry. This method has been applied to crash-dummy models, and will in the future also be applied to human body models. The 1st step of the method is to generate a set of target anthropomethry parameters from a

  14. Ekman Spiral in Horizontally Inhomogeneous Ocean with Varying Eddy Viscosity

    Science.gov (United States)

    2015-01-01

    1 Ekman Spiral in Horizontally Inhomogeneous Ocean with Varying Eddy Viscosity...Oceanography Naval Postgraduate School, Monterey, California, USA Manuscript Click here to download Manuscript: Ekman -chu-pageoph-rev.docx 1...currently valid OMB control number. 1. REPORT DATE 2015 2. REPORT TYPE 3. DATES COVERED 00-00-2015 to 00-00-2015 4. TITLE AND SUBTITLE Ekman Spiral

  15. Artificial Bee Colony Algorithm with Time-Varying Strategy

    Directory of Open Access Journals (Sweden)

    Quande Qin

    2015-01-01

    Full Text Available Artificial bee colony (ABC is one of the newest additions to the class of swarm intelligence. ABC algorithm has been shown to be competitive with some other population-based algorithms. However, there is still an insufficiency that ABC is good at exploration but poor at exploitation. To make a proper balance between these two conflictive factors, this paper proposed a novel ABC variant with a time-varying strategy where the ratio between the number of employed bees and the number of onlooker bees varies with time. The linear and nonlinear time-varying strategies can be incorporated into the basic ABC algorithm, yielding ABC-LTVS and ABC-NTVS algorithms, respectively. The effects of the added parameters in the two new ABC algorithms are also studied through solving some representative benchmark functions. The proposed ABC algorithm is a simple and easy modification to the structure of the basic ABC algorithm. Moreover, the proposed approach is general and can be incorporated in other ABC variants. A set of 21 benchmark functions in 30 and 50 dimensions are utilized in the experimental studies. The experimental results show the effectiveness of the proposed time-varying strategy.

  16. Coupling currents in Rutherford cables under time varying conditions

    NARCIS (Netherlands)

    Verweij, A.P.; Kate, ten H.H.J.

    1993-01-01

    A network model is presented to simulate fully transposed Rutherford cables under time varying conditions. The intrinsic properties of the cable and the external applied conditions can be changed spatially. Several statistical distributions of the contact resistances are built in to investigate loca

  17. Influence of varied doping structure on photoemissive property of photocathode

    Institute of Scientific and Technical Information of China (English)

    Niu Jun; Zhang Yi-Jun; Chang Ben-Kang; Xiong Ya-Juan

    2011-01-01

    The built-in electric fields within a varied doping GaAs photocathode may promote the transport of electrons from the bulk to the surface, thus the quantum efficiency of the cathode can be enhanced remarkably. But this enhancement,which might be due to the increase in either the number or the energy of electrons reaching the surface, is not clear at present. In this paper, the energy distributions of electrons in a varied doping photocathode and uniform doping photocathode before and after escaping from the cathode surface are analysed, and the number of electrons escaping from the surface in different cases is calculated for the two kinds of photocathodes. The results indicate that the varied doping structure can not only increase the number of electrons reaching the surface but also cause an offset of the electron energy distribution to high energy. That is the root reason for the enhancement of the quantum efficiency of a varied doping GaAs photocathode.

  18. Time-varying correlation and common structures in volatility

    NARCIS (Netherlands)

    Liu, Yang

    2016-01-01

    This thesis studies time series properties of the covariance structure of multivariate asset returns. First, the time-varying feature of correlation is investigated at the intraday level with a new correlation model incorporating the intraday correlation dynamics. Second, the thesis develops a

  19. Performance and cost implication of finisher turkeys fed varying ...

    African Journals Online (AJOL)

    Performance and cost implication of finisher turkeys fed varying levels of rice millingwaste. ... Log in or Register to get access to full text downloads. ... 50% rice milling waste produced enhanced performance that was next to the control in terms ...

  20. Additional Surgery after Breast-Conserving Surgery Varies Widely

    Science.gov (United States)

    A study published in the Feb. 1, 2012, issue of JAMA found that the number of women who have one or more additional surgeries to remove suspected residual tumor tissue (re-excisions) following breast-conserving surgery (BCS) for breast cancer varies widely across surgeons and hospitals.

  1. Karlovy Varys linastub kaks Eesti filmi / Andris Feldmanis

    Index Scriptorium Estoniae

    Feldmanis, Andris, 1982-

    2007-01-01

    Ilmar Raagi mängufilm "Klass" osaleb 42. Karlovy Vary rahvusvahelise filmifestivali võistlusprogrammis "East of the West" ja Asko Kase lühimängufilm "Zen läbi prügi" on valitud festivali kõrvalprogrammi "Forum of Independents"

  2. Frontal Neurons Modulate Memory Retrieval across Widely Varying Temporal Scales

    Science.gov (United States)

    Zhang, Wen-Hua; Williams, Ziv M.

    2015-01-01

    Once a memory has formed, it is thought to undergo a gradual transition within the brain from short- to long-term storage. This putative process, however, also poses a unique problem to the memory system in that the same learned items must also be retrieved across broadly varying time scales. Here, we find that neurons in the ventrolateral…

  3. High and varying prices for privately insured patients underscore hospital market power.

    Science.gov (United States)

    White, Chapin; Bond, Amelia M; Reschovsky, James D

    2013-09-01

    Across 13 selected U.S. metropolitan areas, hospital prices for privately insured patients are much higher than Medicare payment rates and vary widely across and within markets, according to a study by the Center for Studying Health System Change (HSC) based on claims data for about 590,000 active and retired nonelderly autoworkers and their dependents. Across the 13 communities, aver­age hospital prices for privately insured patients are about one-and-a-half times Medicare rates for inpatient care and two times what Medicare pays for outpa­tient care. Within individual communities, prices vary widely, with the highest-priced hospital typically paid 60 percent more for inpatient services than the lowest-priced hospital. The price gap within markets is even greater for hospital outpatient care, with the highest-priced hospital typically paid nearly double the lowest-priced hospital. In contrast to the wide variation in hospital prices for pri­vately insured patients across and within markets, prices for primary care physi­cian services generally are close to Medicare rates and vary little within markets. Prices for specialist physician services, however, are higher relative to Medicare and vary more across and within markets. Of the 13 markets, five are in Michigan, which has an unusually concentrated private insurance market, with one insurer commanding a 70-percent market share. Despite the presence of a dominant insurer, almost all Michigan hospi­tals command prices that are higher than Medicare, and some hospitals com­mand prices that are twice what Medicare pays. In the eight markets outside of Michigan, private insurers generally pay even higher hospital prices, with even wider gaps between high- and low-priced hospitals. The variation in hospital and specialist physician prices within communities underscores that some hospitals and physicians have significant market power to command high prices, even in markets with a dominant insurer.

  4. Age related reference ranges for respiration rate and heart rate from 4 to 16 years

    OpenAIRE

    Wallis, L; Healy, M.; Undy, M; Maconochie, I

    2005-01-01

    Background: Clinical vital signs in children (temperature, heart rate, respiration rate, and blood pressure) are an integral part of clinical assessment of degree of illness or normality. Despite this, only blood pressure and temperature have a reliable evidence base. The accepted ranges of heart and respiration rate vary widely.

  5. NEW EFFICIENT ESTIMATION AND VARIABLE SELECTION METHODS FOR SEMIPARAMETRIC VARYING-COEFFICIENT PARTIALLY LINEAR MODELS.

    Science.gov (United States)

    Kai, Bo; Li, Runze; Zou, Hui

    2011-02-01

    The complexity of semiparametric models poses new challenges to statistical inference and model selection that frequently arise from real applications. In this work, we propose new estimation and variable selection procedures for the semiparametric varying-coefficient partially linear model. We first study quantile regression estimates for the nonparametric varying-coefficient functions and the parametric regression coefficients. To achieve nice efficiency properties, we further develop a semiparametric composite quantile regression procedure. We establish the asymptotic normality of proposed estimators for both the parametric and nonparametric parts and show that the estimators achieve the best convergence rate. Moreover, we show that the proposed method is much more efficient than the least-squares-based method for many non-normal errors and that it only loses a small amount of efficiency for normal errors. In addition, it is shown that the loss in efficiency is at most 11.1% for estimating varying coefficient functions and is no greater than 13.6% for estimating parametric components. To achieve sparsity with high-dimensional covariates, we propose adaptive penalization methods for variable selection in the semiparametric varying-coefficient partially linear model and prove that the methods possess the oracle property. Extensive Monte Carlo simulation studies are conducted to examine the finite-sample performance of the proposed procedures. Finally, we apply the new methods to analyze the plasma beta-carotene level data.

  6. Time-varying land subsidence detected by radar altimetry: California, Taiwan and north China.

    Science.gov (United States)

    Hwang, Cheinway; Yang, Yuande; Kao, Ricky; Han, Jiancheng; Shum, C K; Galloway, Devin L; Sneed, Michelle; Hung, Wei-Chia; Cheng, Yung-Sheng; Li, Fei

    2016-06-21

    Contemporary applications of radar altimetry include sea-level rise, ocean circulation, marine gravity, and icesheet elevation change. Unlike InSAR and GNSS, which are widely used to map surface deformation, altimetry is neither reliant on highly temporally-correlated ground features nor as limited by the available spatial coverage, and can provide long-term temporal subsidence monitoring capability. Here we use multi-mission radar altimetry with an approximately 23 year data-span to quantify land subsidence in cropland areas. Subsidence rates from TOPEX/POSEIDON, JASON-1, ENVISAT, and JASON-2 during 1992-2015 show time-varying trends with respect to displacement over time in California's San Joaquin Valley and central Taiwan, possibly related to changes in land use, climatic conditions (drought) and regulatory measures affecting groundwater use. Near Hanford, California, subsidence rates reach 18 cm yr(-1) with a cumulative subsidence of 206 cm, which potentially could adversely affect operations of the planned California High-Speed Rail. The maximum subsidence rate in central Taiwan is 8 cm yr(-1). Radar altimetry also reveals time-varying subsidence in the North China Plain consistent with the declines of groundwater storage and existing water infrastructure detected by the Gravity Recovery And Climate Experiment (GRACE) satellites, with rates reaching 20 cm yr(-1) and cumulative subsidence as much as 155 cm.

  7. Time-varying land subsidence detected by radar altimetry: California, Taiwan and north China

    Science.gov (United States)

    Hwang, Cheinway; Yang, Yuande; Kao, Ricky; Han, Jiancheng; Shum, C.K.; Galloway, Devin L.; Sneed, Michelle; Hung, Wei-Chia; Cheng, Yung-Sheng; Li, Fei

    2016-01-01

    Contemporary applications of radar altimetry include sea-level rise, ocean circulation, marine gravity, and ice sheet elevation change. Unlike InSAR and GNSS, which are widely used to map surface deformation, altimetry is neither reliant on highly temporally-correlated ground features nor as limited by the available spatial coverage, and can provide long-term temporal subsidence monitoring capability. Here we use multi-mission radar altimetry with an approximately 23 year data-span to quantify land subsidence in cropland areas. Subsidence rates from TOPEX/POSEIDON, JASON-1, ENVISAT, and JASON-2 during 1992–2015 show time-varying trends with respect to displacement over time in California’s San Joaquin Valley and central Taiwan, possibly related to changes in land use, climatic conditions (drought) and regulatory measures affecting groundwater use. Near Hanford, California, subsidence rates reach 18 cm/yr with a cumulative subsidence of 206 cm, which potentially could adversely affect operations of the planned California High-Speed Rail. The maximum subsidence rate in central Taiwan is 8 cm/yr. Radar altimetry also reveals time-varying subsidence in the North China Plain consistent with the declines of groundwater storage and existing water infrastructure detected by the Gravity Recovery And Climate Experiment (GRACE) satellites, with rates reaching 20 cm/yr and cumulative subsidence as much as 155 cm.

  8. Time-varying land subsidence detected by radar altimetry: California, Taiwan and north China

    Science.gov (United States)

    Hwang, Cheinway; Yang, Yuande; Kao, Ricky; Han, Jiancheng; Shum, C. K.; Galloway, Devin L.; Sneed, Michelle; Hung, Wei-Chia; Cheng, Yung-Sheng; Li, Fei

    2016-06-01

    Contemporary applications of radar altimetry include sea-level rise, ocean circulation, marine gravity, and icesheet elevation change. Unlike InSAR and GNSS, which are widely used to map surface deformation, altimetry is neither reliant on highly temporally-correlated ground features nor as limited by the available spatial coverage, and can provide long-term temporal subsidence monitoring capability. Here we use multi-mission radar altimetry with an approximately 23 year data-span to quantify land subsidence in cropland areas. Subsidence rates from TOPEX/POSEIDON, JASON-1, ENVISAT, and JASON-2 during 1992–2015 show time-varying trends with respect to displacement over time in California’s San Joaquin Valley and central Taiwan, possibly related to changes in land use, climatic conditions (drought) and regulatory measures affecting groundwater use. Near Hanford, California, subsidence rates reach 18 cm yr‑1 with a cumulative subsidence of 206 cm, which potentially could adversely affect operations of the planned California High-Speed Rail. The maximum subsidence rate in central Taiwan is 8 cm yr‑1. Radar altimetry also reveals time-varying subsidence in the North China Plain consistent with the declines of groundwater storage and existing water infrastructure detected by the Gravity Recovery And Climate Experiment (GRACE) satellites, with rates reaching 20 cm yr‑1 and cumulative subsidence as much as 155 cm.

  9. 38 CFR 4.15 - Total disability ratings.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Total disability ratings... FOR RATING DISABILITIES General Policy in Rating § 4.15 Total disability ratings. The ability to overcome the handicap of disability varies widely among individuals. The rating, however, is...

  10. The optimal manufacturing batch size with rework under time-varying demand process for a finite time horizon

    Science.gov (United States)

    Musa, Sarah; Supadi, Siti Suzlin; Omar, Mohd

    2014-07-01

    Rework is one of the solutions to some of the main issues in reverse logistic and green supply chain as it reduces production cost and environmental problem. Many researchers focus on developing rework model, but to the knowledge of the author, none of them has developed a model for time-varying demand rate. In this paper, we extend previous works and develop multiple batch production system for time-varying demand rate with rework. In this model, the rework is done within the same production cycle.

  11. Control of Linear Parameter Varying Systems with Applications

    CERN Document Server

    Mohammadpour, Javad

    2012-01-01

    Control of Linear Parameter Varying Systems with Applications compiles state-of-the-art contributions on novel analytical and computational methods to address system modeling and identification, complexity reduction, performance analysis and control design for time-varying and nonlinear systems in the LPV framework. The book has an interdisciplinary character by emphasizing techniques that can be commonly applied in various engineering fields. It also includes a rich collection of illustrative applications in diverse domains to substantiate the effectiveness of the design methodologies and provide pointers to open research directions. The book is divided into three parts. The first part collects chapters of a more tutorial character on the background of LPV systems modeling and control. The second part gathers chapters devoted to the theoretical advancement of LPV analysis and synthesis methods to cope with the design constraints such as uncertainties and time delay. The third part of the volume showcases con...

  12. Dynamic Server Allocation over Time Varying Channels with Switchover Delay

    CERN Document Server

    Celik, Güner D; Modiano, Eytan

    2012-01-01

    We consider a dynamic server allocation problem over parallel queues with randomly varying connectivity and server switchover delay between the queues. At each time slot the server decides either to stay with the current queue or switch to another queue based on the current connectivity and the queue length information. Switchover delay occurs in many telecommunications applications and is a new modeling component of this problem that has not been previously addressed. We show that the simultaneous presence of randomly varying connectivity and switchover delay changes the system stability region and the structure of optimal policies. In the first part of the paper, we consider a system of two parallel queues, and develop a novel approach to explicitly characterize the stability region of the system using state-action frequencies which are stationary solutions to a Markov Decision Process (MDP) formulation. We then develop a frame-based dynamic control (FBDC) policy, based on the state-action frequencies, and ...

  13. Cooperative Output Regulation of Multiagent Linear Parameter-Varying Systems

    Directory of Open Access Journals (Sweden)

    Afshin Mesbahi

    2017-01-01

    Full Text Available The output regulation problem is examined in this paper for a class of heterogeneous multiagent systems whose dynamics are governed by polytopic linear parameter-varying (LPV models. The dynamics of the agents are decoupled from each other but the agents’ controllers are assumed to communicate. To design the cooperative LPV controllers, analysis conditions for closed-loop system are first established to ensure stability and reference tracking. Then, the LPV control synthesis problem is addressed, where the offline solution to a time-varying Sylvester equation will be used to determine and update in real time the controller state-space matrices. Two numerical examples will be finally given to demonstrate the efficacy of the proposed cooperative design method.

  14. Modeling and Analysis of Time-Varying Graphs

    CERN Document Server

    Basu, Prithwish; Ramanathan, Ram; Johnson, Matthew P

    2010-01-01

    We live in a world increasingly dominated by networks -- communications, social, information, biological etc. A central attribute of many of these networks is that they are dynamic, that is, they exhibit structural changes over time. While the practice of dynamic networks has proliferated, we lag behind in the fundamental, mathematical understanding of network dynamism. Existing research on time-varying graphs ranges from preliminary algorithmic studies (e.g., Ferreira's work on evolving graphs) to analysis of specific properties such as flooding time in dynamic random graphs. A popular model for studying dynamic graphs is a sequence of graphs arranged by increasing snapshots of time. In this paper, we study the fundamental property of reachability in a time-varying graph over time and characterize the latency with respect to two metrics, namely store-or-advance latency and cut-through latency. Instead of expected value analysis, we concentrate on characterizing the exact probability distribution of routing l...

  15. Late time attractors of some varying Chaplygin gas cosmological models

    CERN Document Server

    Khurshudyan, M

    2015-01-01

    Varying Chaplygin gas is one of the dark fluids actively studied in modern cosmology. It does belong to the group of the fluids which has an explicitly given EoS. From the other hand phase space does contain all possible states of the system. Therefore, phase space analysis of the cosmological models does allow to understand qualitative behavior and estimate required characteristics of the models. Phase space analysis is a convenient approach to study a cosmological model, because we do not need to solve a system of differential equations for a given initial conditions, instead, we need to deal with appropriate algebraic equations. The goal of this paper is to find late time attractors for the cosmological models, where a varying Chaplygin gas is one of the components of the large sale universe. We will pay our attention to some non linear interacting models.

  16. Black holes in Varying Speed of Light Theory

    CERN Document Server

    Shojaie, H

    2002-01-01

    We consider the effect of \\emph{``Varying Speed of Light''} (VSL) theory on the no-charge and non-rotating black holes. We show that in any varying-$c$ theory, the Schwarzschild solution is no more static and even stationary. Also the singularity in the Schwarzschild horizon can not be removed by coordinate transformation. So except initial mass of star, no matter can enter the horizon and the interior part of the black hole separates from the whole manifold. If $\\dot{c}<0$, then the size of Schwarzschild radius increases in time and since the entropy of the black hole is proportional to its surface area of event horizon, it increases in this case. The higher value of speed of light in the early universe may cause the creation probability of primordial black holes and their population nowadays decreases enormously.

  17. A variational image restoration with spatially varying noise

    Science.gov (United States)

    Bao, Zheng; Bai, Hua; Liu, Ruihua; Shen, Chaomin

    2008-10-01

    The noise in natural images sometimes changes according to imaging mechanism or local image information. This is called spatially varying noise. It is obvious that classical variational denoising algorithms such as the Rudin-Osher-Fatemi model are not suitable for this kind of noise. We propose a variational method to remove this spatially varying noise based on the estimation of local variance for a given image, such that high noise regions are smoothed meanwhile the textures and certain details in low noise regions are preserved. Moreover, we give the proof of existence of the minimizer of our proposed functional. The experimental results show visual improvement and high signal-to-noise ratio over other variational denoising models.

  18. Poverty Index With Time Varying Consumption and Income Distributions

    CERN Document Server

    Chattopadhyay, Amit K; Mallick, Sushanta K

    2016-01-01

    In a recent work (Chattopadhyay, A. K. et al, Europhys. Lett. {\\bf 91}, 58003, 2010) based on food consumption statistics, we showed how a stochastic agent based model could represent the time variation of the income distribution statistics in a developing economy, thereby defining an alternative \\enquote{poverty index} (PI) that largely agreed with poverty gap index data. This PI used two variables, the probability density function of the income statistics and a consumption deprivation (CD) function, representing the shortfall in the minimum consumption needed for survival. Since the time dependence of the CD function was introduced there through data extrapolation only and not through an endogenous time dependent series, this model left unexplained how the minimum consumption needed for survival varies with time. The present article overcomes these limitations and arrives at a new unified theoretical structure through time varying consumption and income distributions where trade is only allowed when the inc...

  19. Structured Linear Parameter Varying Control of Wind Turbines

    DEFF Research Database (Denmark)

    Adegas, Fabiano Daher; Sloth, Christoffer; Stoustrup, Jakob

    2012-01-01

    is presented. We specifically consider variable-speed, variable-pitch wind turbines with faults on actuators and sensors. Linear parameter-varying (LPV) controllers can be designed by a proposed method that allows the inclusion of faults in the LPV controller design. Moreover, the controller structure can......High performance and reliability are required for wind turbines to be competitive within the energy market. To capture their nonlinear behavior, wind turbines are often modeled using parameter-varying models. In this chapter, a framework for modelling and controller design of wind turbines...... be arbitrarily chosen: static output feedback, dynamic (reduced order) output feedback, decentralized, among others. The controllers are scheduled on an estimated wind speed to manage the parametervarying nature of the model and on information from a fault diagnosis system. The optimization problems involved...

  20. Nonlinear scale space with spatially varying stopping time.

    Science.gov (United States)

    Gilboa, Guy

    2008-12-01

    A general scale space algorithm is presented for denoising signals and images with spatially varying dominant scales. The process is formulated as a partial differential equation with spatially varying time. The proposed adaptivity is semi-local and is in conjunction with the classical gradient-based diffusion coefficient, designed to preserve edges. The new algorithm aims at maximizing a local SNR measure of the denoised image. It is based on a generalization of a global stopping time criterion presented recently by the author and colleagues. Most notably, the method works well also for partially textured images and outperforms any selection of a global stopping time. Given an estimate of the noise variance, the procedure is automatic and can be applied well to most natural images.

  1. A nonlinear truss finite element with varying stiffness

    Directory of Open Access Journals (Sweden)

    Ďuriš R.

    2007-11-01

    Full Text Available This contribution deals with a new truss element with varying stiffness intended to geometric and physically nonlinear analysis of composite structures. We present a two-node straight composite truss finite element derived by new nonincremental full geometric nonlinear approach. Stiffness matrix of this composite truss contains transfer constants, which accurately describe the polynomial longitudinal variation of cross-section area and material properties. These variations could be caused by nonhomogenous temperature field or by varying components volume fractions of the composite or/and functionally graded materials (FGM´s. Numerical examples were solved to verify the established relations. The accuracy of the new proposed finite truss element are compared and discused.

  2. Hemolymph drop impact outcomes on surfaces with varying wettability

    Science.gov (United States)

    Milionis, Athanasios; Ghokulla Krishnan, K.; Loth, Eric

    2015-08-01

    Insect fouling from coagulated hemolymph and exoskeleton parts is a major challenge in the aerospace industry for the next generation of aerodynamic surfaces, which will employ laminar flow that requires extremely smooth surfaces. However, the wetting physics and dynamics of hemolymph (insect blood) on surfaces are not well understood. The present study seeks to gain a fundamental insight on the effect of surface wetting characteristics and dynamics resulting from a hemolymph drop impact, the first such study. In particular, hemolymph drops extracted from Acheta domesticus were dispensed from a range of heights to vary the kinetic impact on surfaces, which had widely varying water wetting behavior (from superhydrophilic to superhydrophobic). The impact dynamics were investigated with high-speed imaging while the dried residues were studied with optical microscopy. It was found that a superhydrophobic surface (based on thermoplastic with silica nano-particles) was able to significantly reduce hemolymph drop spreading, and even provide complete rebound when impacting on inclined surfaces.

  3. Stabilising compensators for linear time-varying differential systems

    Science.gov (United States)

    Oberst, Ulrich

    2016-04-01

    In this paper, we describe a constructive test to decide whether a given linear time-varying (LTV) differential system admits a stabilising compensator for the control tasks of tracking, disturbance rejection or model matching and construct and parametrise all of them if at least one exists. In analogy to the linear time-invariant (LTI) case, the ring of stable rational functions, noncommutative in the LTV situation, and the Kučera-Youla parametrisation play prominent parts in the theory. We transfer Blumthaler's thesis from the LTI to the LTV case and sharpen, complete and simplify the corresponding results in the book 'Linear Time-Varying Systems' by Bourlès and Marinescu.

  4. Modelling Time-Varying Volatility in Financial Returns

    DEFF Research Database (Denmark)

    Amado, Cristina; Laakkonen, Helinä

    2014-01-01

    The “unusually uncertain” phase in the global financial markets has inspired many researchers to study the effects of ambiguity (or “Knightian uncertainty”) on the decisions made by investors and their implications for the capital markets. We contribute to this literature by using a modified...... version of the time-varying GARCH model of Amado and Teräsvirta (2013) to analyze whether the increasing uncertainty has caused excess volatility in the US and European government bond markets. In our model, volatility is multiplicatively decomposed into two time-varying conditional components: the first...... being captured by a stable GARCH(1,1) process and the second driven by the level of uncertainty in the financial market....

  5. Free electron lasers with slowly varying beam and undulator parameters

    Directory of Open Access Journals (Sweden)

    Z. Huang

    2005-04-01

    Full Text Available A self-consistent theory of a free electron laser (FEL with slowly varying beam and undulator parameters is developed using the WKB approximation. The theory is applied to study the performance of a self-amplified spontaneous emission (SASE FEL when the electron beam energy varies along the undulator as would be caused by vacuum pipe wakefields and/or when the undulator strength parameter is tapered in the small signal regime before FEL saturation. We find that a small energy gain or an equivalent undulator taper slightly reduces the power gain length in the exponential growth regime and can increase the saturated SASE power by about a factor of 2. Power degradation away from the optimal performance can be estimated based upon knowledge of the SASE bandwidth. The analytical results, which agree with numerical simulations, are used to optimize the undulator taper and to evaluate wakefield effects.

  6. Vehicle routing problem with time-varying speed

    Institute of Scientific and Technical Information of China (English)

    LIU Yun-zhong

    2010-01-01

    Vehicle routing problem with time-varying speed(VRPTS)is a generalization of vehicle routing problem in which the travel speed between two locations depends on the passing areas and the time of a day.This paper proposes a simple model for estimating time-varying travel speeds in VRPTS that relieves much bur den to the data-related problems.The study further presents three heuristics(saving technique,proximity priority searching technique,and insertion technique)for VRPTS,developed by extending and modifying the existing heuristics for conventional VRP.The results of computational experiments demonstrate that the proposed estimation model performs well and the saving technique is the best among the three heuristics.

  7. Prediction of Fatigue Life of Gear Subjected to Varying Loads

    Directory of Open Access Journals (Sweden)

    D. Hanumanna

    1998-07-01

    Full Text Available Structural members and components of a vehicle during service are subjected to varying loads which are random in nature. For structural members subjected to loads of constant amplitude, it is possible to describe the load with explicit mathematical relationship, and thereby, the life span can be estimated. Whereas, for structural members subjected to varying loads with time, there is no satisfactory method to estimate their life span. This paper describes a method for the estimation of life span of a gear in the gear box of a fighting vehicle subjected to fluctuating loads. For this purpose, it is assumed that the load spectrum corresponds to Gaussian (normal distribution, and the life has been worked out by applying linear cumulative damage theory.

  8. Varying fine structure "constant" and charged black holes

    CERN Document Server

    Bekenstein, Jacob D

    2009-01-01

    Tension between varying fine-structure "constant'' alpha and charged black hole properties has been invoked in the past to place constraints on cosmological variability of alpha. However, the properties used are those of the standard Reissner-Nordstrom black holes; this ignores modifications of black hole structure that must result from alpha variability. To elucidate this issue we have derived, in 4-D general relativity, and using isotropic coordinates, the solution for a charged spherical black hole according to the framework for dynamical variability of alpha which does not fix its overall scale. This solution coincides with a known one-parameter extension of the dilatonic black hole family. Among the notable properties of varying alpha charged black holes are adherence to the "no hair'' principle, the absence of the inner (Cauchy) horizon, the nonexistence of precisely extremal black holes, and the appearance of naked singularities in a separate sector of the relevant metric. This last hints at the possib...

  9. Effects of varying interfacial surface tension on macroscopic polymer lenses

    Science.gov (United States)

    Zimmerman, Charlotte; White, Mason; Baylor, Martha-Elizabeth

    2015-09-01

    We investigate macroscopic polymer lenses (0.5- to 2.5-cm diameter) fabricated by dropping hydrophobic photocurable resin onto the surface of various hydrophilic liquid surfaces. Due to the intermolecular forces along the interface between the two liquids, a lens shape is formed. We find that we can vary the lens geometry by changing the region over which the resin is allowed to spread and the surface tension of the substrate to produce lenses with theoretically determined focal lengths ranging from 5 to 25 mm. These effects are varied by changing the container width, substrate composition, and substrate temperature. We present data for five different variants, demonstrating that we can control the lens dimensions for polymer lens applications that require high surface quality.

  10. Finite mixture varying coefficient models for analyzing longitudinal heterogenous data.

    Science.gov (United States)

    Lu, Zhaohua; Song, Xinyuan

    2012-03-15

    This paper aims to develop a mixture model to study heterogeneous longitudinal data on the treatment effect of heroin use from a California Civil Addict Program. Each component of the mixture is characterized by a varying coefficient mixed effect model. We use the Bayesian P-splines approach to approximate the varying coefficient functions. We develop Markov chain Monte Carlo algorithms to estimate the smooth functions, unknown parameters, and latent variables in the model. We use modified deviance information criterion to determine the number of components in the mixture. A simulation study demonstrates that the modified deviance information criterion selects the correct number of components and the estimation of unknown quantities is accurate. We apply the proposed model to the heroin treatment study. Furthermore, we identify heterogeneous longitudinal patterns.

  11. Local Feature Learning for Face Recognition under Varying Poses

    DEFF Research Database (Denmark)

    Duan, Xiaodong; Tan, Zheng-Hua

    2015-01-01

    In this paper, we present a local feature learning method for face recognition to deal with varying poses. As opposed to the commonly used approaches of recovering frontal face images from profile views, the proposed method extracts the subject related part from a local feature by removing the pose...... related part in it on the basis of a pose feature. The method has a closed-form solution, hence being time efficient. For performance evaluation, cross pose face recognition experiments are conducted on two public face recognition databases FERET and FEI. The proposed method shows a significant...... recognition improvement under varying poses over general local feature approaches and outperforms or is comparable with related state-of-the-art pose invariant face recognition approaches. Copyright ©2015 by IEEE....

  12. Varied morphology carbon nanotubes and method for their manufacture

    Science.gov (United States)

    Li, Wenzhi; Wen, Jian Guo; Ren, Zhi Feng

    2007-01-02

    The present invention describes the preparation of carbon nanotubes of varied morphology, catalyst materials for their synthesis. The present invention also describes reactor apparatus and methods of optimizing and controlling process parameters for the manufacture carbon nanotubes with pre-determined morphologies in relatively high purity and in high yields. In particular, the present invention provides methods for the preparation of non-aligned carbon nanotubes with controllable morphologies, catalyst materials and methods for their manufacture.

  13. Premorbid IQ varies across different definitions of schizophrenia

    DEFF Research Database (Denmark)

    Urfer Parnas, Annick; Jansson, Lennart; Handest, Peter

    2007-01-01

    The nature of the association between IQ and schizophrenia is still unclear. So far no study addressed this issue in relation to the breadth or scope of the very concept of schizophrenia. We examined the premorbid IQ in a polydiagnostic study with four classifications of schizophrenia: ICD-8/9, I...... of schizophrenia in relation to IQ revealed associations between low premorbid IQ and hallucinations as well as negative symptoms. It is concluded that premorbid IQ varies across different definitions of schizophrenia....

  14. Tracking time-varying parameters with local regression

    DEFF Research Database (Denmark)

    Joensen, Alfred Karsten; Nielsen, Henrik Aalborg; Nielsen, Torben Skov;

    2000-01-01

    This paper shows that the recursive least-squares (RLS) algorithm with forgetting factor is a special case of a varying-coe\\$cient model, and a model which can easily be estimated via simple local regression. This observation allows us to formulate a new method which retains the RLS algorithm, bu......, but extends the algorithm by including polynomial approximations. Simulation results are provided, which indicates that this new method is superior to the classical RLS method, if the parameter variations are smooth....

  15. Possible Cosmological Implications of Time Varying Fine Structure Constant

    CERN Document Server

    Berman, M S; Berman, Marcelo S.; Trevisan, Luis A.

    2001-01-01

    We make use of Dirac LNH and results for a time varying fine structure constant in order to derive possible laws of variation for speed of light, the number of nucleons in the Universe, energy density and gravitational constant. By comparing with experimental bounds on G variation, we find that the deceleration paramenter of the present Universe is negative. This is coherent with recent Supernovae observations.

  16. Simple Model with Time-Varying Fine-Structure ``Constant''

    Science.gov (United States)

    Berman, M. S.

    2009-10-01

    Extending the original version written in colaboration with L.A. Trevisan, we study the generalisation of Dirac's LNH, so that time-variation of the fine-structure constant, due to varying electrical and magnetic permittivities is included along with other variations (cosmological and gravitational ``constants''), etc. We consider the present Universe, and also an inflationary scenario. Rotation of the Universe is a given possibility in this model.

  17. Spatially-varying IIR filter banks for image coding

    Science.gov (United States)

    Chung, Wilson C.; Smith, Mark J. T.

    1992-01-01

    This paper reports on the application of spatially variant infinite impulse response (IIR) filter banks to subband image coding. The new filter bank is based on computationally efficient recursive polyphase decompositions that dynamically change in response to the input signal. In the absence of quantization, reconstruction can be made exact. However, by proper choice of an adaptation scheme, we show that subband image coding based on time varying filter banks can yield improvement over the use of conventional filter banks.

  18. Flexible Foraging of Ants under Unsteadily Varying Environment

    Science.gov (United States)

    Tao, Tomomi; Nakagawa, Hiroyuki; Yamasaki, Masato; Nishimori, Hiraku

    2004-08-01

    Using a simple model for the trail formation of ants, the relation between i) the schedule of feeding which represents the unsteady natural environment, ii) emerging patterns of trails connecting a nest with food resources, and iii) the foraging efficiency is studied. Simulations and a simple analysis show that the emergent trail pattern flexibly varies depending on the feeding schedule by which ants can make an efficient foraging according to the underlying unsteady environment.

  19. Varying the exchange interaction between NiO nanoparticles

    DEFF Research Database (Denmark)

    Bahl, Christian Robert Haffenden; Mørup, Steen

    2006-01-01

    We demonstrate that exchange interactions between antiferromagnetic nanoparticles of 57Fe-doped NiO can be varied by simple macroscopic treatments. Mössbauer spectroscopy studies of the superparamagnetic relaxation behaviour show that grinding or suspension in water of nanoparticles of NiO can...... significantly reduce interparticle interactions. Slow drying of aqueous suspensions of NiO nanoparticles did not lead to enhanced interparticle interactions. This is opposite to the behaviour of α-Fe2O3 (hematite) nanoparticles....

  20. STABILITY OF TIME VARYING SINGULAR DIFFERENTIAL SYSTEMS WITH DELAY

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this paper, stability of time varying singular differential systems with delay is considered. Based on variation formula and Gronwall-Bellman integral inequality, we obtain the exponential estimation of the solution and the sufficient conditions under which the considered system is stable and exponentially asymptotically stable. These results will be very useful to further research on Roust stability and control design of uncertain singular control systems with delay.

  1. Varying the exchange interaction between NiO nanoparticles

    DEFF Research Database (Denmark)

    Bahl, Christian Robert Haffenden; Mørup, Steen

    2006-01-01

    We demonstrate that exchange interactions between antiferromagnetic nanoparticles of 57Fe-doped NiO can be varied by simple macroscopic treatments. Mössbauer spectroscopy studies of the superparamagnetic relaxation behaviour show that grinding or suspension in water of nanoparticles of NiO can...... significantly reduce interparticle interactions. Slow drying of aqueous suspensions of NiO nanoparticles did not lead to enhanced interparticle interactions. This is opposite to the behaviour of α-Fe2O3 (hematite) nanoparticles....

  2. Morphable Word Clouds for Time-Varying Text Data Visualization.

    Science.gov (United States)

    Chi, Ming-Te; Lin, Shih-Syun; Chen, Shiang-Yi; Lin, Chao-Hung; Lee, Tong-Yee

    2015-12-01

    A word cloud is a visual representation of a collection of text documents that uses various font sizes, colors, and spaces to arrange and depict significant words. The majority of previous studies on time-varying word clouds focuses on layout optimization and temporal trend visualization. However, they do not fully consider the spatial shapes and temporal motions of word clouds, which are important factors for attracting people's attention and are also important cues for human visual systems in capturing information from time-varying text data. This paper presents a novel method that uses rigid body dynamics to arrange multi-temporal word-tags in a specific shape sequence under various constraints. Each word-tag is regarded as a rigid body in dynamics. With the aid of geometric, aesthetic, and temporal coherence constraints, the proposed method can generate a temporally morphable word cloud that not only arranges word-tags in their corresponding shapes but also smoothly transforms the shapes of word clouds over time, thus yielding a pleasing time-varying visualization. Using the proposed frame-by-frame and morphable word clouds, people can observe the overall story of a time-varying text data from the shape transition, and people can also observe the details from the word clouds in frames. Experimental results on various data demonstrate the feasibility and flexibility of the proposed method in morphable word cloud generation. In addition, an application that uses the proposed word clouds in a simulated exhibition demonstrates the usefulness of the proposed method.

  3. Representations and Metrics for Time-Varying Terrain Surfaces

    Science.gov (United States)

    2013-08-06

    multiple terrain scans. The individual scans are point clouds augmented with a varying probability density functions at each sample point. A scalar...system. The boxes are individual executable programs and the cylinders are data files. The Point-Set Generator generates simple test point clouds , such... point clouds to a height-field raster, displayable as a gray-scale image. We first investigated using a 3D, volumetric variant of SIFT which stacks

  4. Dissipativity Analysis of Neural Networks with Time-varying Delays

    Institute of Scientific and Technical Information of China (English)

    Yan Sun; Bao-Tong Cui

    2008-01-01

    A new definition of dissipativity for neural networks is presented in this paper. By constructing proper Lyapunov func- tionals and using some analytic techniques, sufficient conditions are given to ensure the dissipativity of neural networks with or without time-varying parametric uncertainties and the integro-differential neural networks in terms of linear matrix inequalities. Numerical examples are given to illustrate the effectiveness of the obtained results.

  5. Testing for time-varying loadings in dynamic factor models

    DEFF Research Database (Denmark)

    Mikkelsen, Jakob Guldbæk

    factors. The squared correlation coefficient times the sample size has a limiting chi-squared distribution. The test can be made robust to serial correlation in the idiosyncratic errors. We find evidence for factor loadings variance in over half of the variables in a dataset for the US economy, while...... there is evidence of time-varying loadings on the risk factors underlying portfolio returns for around 80% of the portfolios....

  6. Holographic flow visualization of time-varying shock waves

    Science.gov (United States)

    Decker, A. J.

    1981-01-01

    Rapid-double-exposure, diffuse-illumination holography is evaluated analytically and experimentally as a flow visualization method for time-varying shock waves. Conditions are determined that minimize the distance (localization error) between the surface or curve of interference-fringe localization and the shock surface. Treated specifically are the cases of shock waves in a transonic compressor rotor for which there is laser anemometer data for comparison and shock waves in a flutter cascade.

  7. Mass-varying massive gravity with k-essence

    Energy Technology Data Exchange (ETDEWEB)

    Tannukij, Lunchakorn [Mahidol University, Department of Physics, Faculty of Science, Bangkok (Thailand); Wongjun, Pitayuth [Naresuan University, The Institute for Fundamental Study, Phitsanulok (Thailand); Thailand Center of Excellence in Physics, Ministry of Education, Bangkok (Thailand)

    2016-01-15

    For a large class of mass-varying massive-gravity models, the graviton mass cannot provide the late-time cosmic expansion of the universe due to its vanishing at late time. In this work, we propose a new class of mass-varying massive gravity models, in which the graviton mass varies according to a kinetic term of a k-essence field. By using a more general form of the fiducial metric, we found a solution such that a non-vanishing graviton mass can drive the accelerated expansion of the universe at late time. We also perform dynamical analyses of such a model and find that without introducing the k-essence Lagrangian, the graviton mass can be responsible for both dark contents of the universe, namely dark energy, which drives the accelerated expansion of the universe, and non-relativistic matter, which plays the role of dark matter. Moreover, by including the k-essence Lagrangian, we find that it is possible to alleviate the so-called cosmic coincidence problem. (orig.)

  8. Contagion dynamics in time-varying metapopulation networks

    Science.gov (United States)

    Perra, Nicola; Liu, Suyu; Baronchelli, Andrea

    2014-03-01

    The metapopulation framework is adopted in a wide array of disciplines to describe systems of well separated yet connected subpopulations. The subgroups/patches are often represented as nodes in a network whose links represent the migration routes among them. The connections has been so far mostly considered as static, but in general evolve in time. Here we address this case by investigating simple contagion processes on time-varying metapopulation networks. We focus on the SIR process, and determine analytically the mobility threshold for the onset of an epidemic spreading in the framework of activity-driven network models. We find profound differences from the case of static networks. The threshold is entirely described by the dynamical parameters defining the average number of instantaneously migrating individuals, and does not depend on the properties of the static network representation. Remarkably, the diffusion and contagion processes are slower in time-varying graphs than in their aggregated static counterparts, the mobility threshold been even two orders of magnitude larger in the first case. The presented results confirm the importance of considering the time-varying nature of complex networks.

  9. On enhanced time-varying distributed H systems

    Directory of Open Access Journals (Sweden)

    Sergey Verlan

    2002-11-01

    Full Text Available An enhanced time-varying distributed H system (ETVDH system is a slightly different definition of the time-varying distributed H system (TVDH system [9] and it was proposed by M. Margenstern and Yu. Rogozhin in [4] under the name of "extended time-varying distributed H system''. The main difference is that the components of the ETVDH system are H systems and therefore splicing rules may be applied more than once as it is done in TVDH systems. This leads to difficulties in investigating the behavior of such systems because they have a higher level of parallelism. It is proved that ETVDH systems of degree 2 (i.e. with 2 components generate all recursively enumerable languages in a sequential way [7] and that ETVDH systems of degree 4 generate all recursively enumerable languages in a "parallel'' way, modelling a formal type-0 grammar [11]. In this paper we improve the last result and we present an ETVDH system of degree 3 which generates all recursively enumerable languages modelling type-0 formal grammars. The problem of the existence of ETVDH systems of degree 2 which generate all recursively enumerable languages in a "parallel'' way is left open.

  10. Sensor trustworthiness in uncertain time varying stochastic environments

    Science.gov (United States)

    Verma, Ajay; Fernandes, Ronald; Vadakkeveedu, Kalyan

    2011-06-01

    Persistent surveillance applications require unattended sensors deployed in remote regions to track and monitor some physical stimulant of interest that can be modeled as output of time varying stochastic process. However, the accuracy or the trustworthiness of the information received through a remote and unattended sensor and sensor network cannot be readily assumed, since sensors may get disabled, corrupted, or even compromised, resulting in unreliable information. The aim of this paper is to develop information theory based metric to determine sensor trustworthiness from the sensor data in an uncertain and time varying stochastic environment. In this paper we show an information theory based determination of sensor data trustworthiness using an adaptive stochastic reference sensor model that tracks the sensor performance for the time varying physical feature, and provides a baseline model that is used to compare and analyze the observed sensor output. We present an approach in which relative entropy is used for reference model adaptation and determination of divergence of the sensor signal from the estimated reference baseline. We show that that KL-divergence is a useful metric that can be successfully used in determination of sensor failures or sensor malice of various types.

  11. Computation of gradually varied flow in compound open channel networks

    Indian Academy of Sciences (India)

    H Prashanth Reddy; M Hanif Chaudhry; Jasim Imran

    2014-12-01

    Although, natural channels are rarely rectangular or trapezoidal in cross section, these cross sections are assumed for the computation of steady, gradually varied flow in open channel networks. The accuracy of the computed results, therefore, becomes questionable due to differences in the hydraulic and geometric characteristics of the main channel and floodplains. To overcome these limitations, an algorithm is presented in this paper to compute steady, gradually varied flow in an open-channel network with compound cross sections. As compared to the presently available methods, the methodology is more general and suitable for application to compound and trapezoidal channel cross sections in series channels, tree-type or looped networks. In this method, the energy and continuity equations are solved for steady, gradually varied flow by the Newton–Raphson method and the proposed methodology is applied to tree-type and looped-channel networks. An algorithm is presented to determine multiple critical depths in a compound channel. Modifications in channel geometry are presented to avoid the occurrence of multiple critical depths. The occurrence of only one critical depth in a compound cross section with modified geometry is demonstrated for a tree-type channel network.

  12. A finite crack with arbitrarily varied surface piezoelectricity

    Science.gov (United States)

    Xu, Yang; Wang, Xu

    2017-01-01

    We study the contribution of arbitrarily varied surface piezoelectricity to the anti-plane deformation and in-plane electric fields of a hexagonal piezoelectric material containing a finite crack. The varied surface piezoelectricity is incorporated by using an extended version of the continuum-based surface/interface model of Gurtin and Murdoch. In our discussion, the surface properties, including the surface elastic stiffness, the surface piezoelectric modulus and the surface dielectric permittivity, are assumed to be varied arbitrarily along the crack surfaces. By using the Green’s function method, the original boundary value problem is reduced to a system of two coupled first-order Cauchy singular integro-differential equations. Through a diagonalization strategy, the coupled system is transformed into two independent singular integro-differential equations, each of which can be numerically solved by using the collocation method. Our results indicate that the variation of the surface electroelastic moduli exerts a significant influence on the crack opening displacement, the electric potential jump across the crack faces and on the strengths of the logarithmic singularity in stresses and electric displacements at the crack tips.

  13. Observational constraint on the varying speed of light theory

    CERN Document Server

    Qi, Jing-Zhao; Liu, Wen-Biao

    2014-01-01

    The varying speed of light (VSL) theory is controversial. It succeeds in explaining some cosmological problems, but on the other hand it is excluded by mainstream physics because it will shake the foundation of physics. In the present paper, we devote ourselves to test whether the speed of light is varying from the observational data of the type Ia Supernova, Baryon Acoustic Oscillation, Observational $H(z)$ data and Cosmic Microwave Background (CMB). We select the common form $c(t)=c_0a^n(t)$ with the contribution of dark energy and matter, where $c_0$ is the current value of speed of light, $n$ is a constant, and consequently construct a varying speed of light dark energy model (VSLDE). The combined observational data show a much trivial constraint $n=-0.0033 \\pm 0.0045$ at 68.3\\% confidence level, which indicates that the speed of light may be a constant with high significance. By reconstructing the time-variable $c(t)$, we find that the speed of light almost has no variation for redshift $z < 10^{-1}$....

  14. Shape and Spatially-Varying Reflectance Estimation From Virtual Exemplars.

    Science.gov (United States)

    Hui, Zhuo; Sankaranarayanan, Aswin C

    2016-11-01

    This paper addresses the problem of estimating the shape of objects that exhibit spatially-varying reflectance. We assume that multiple images of the object are obtained under a fixed view-point and varying illumination, i.e., the setting of photometric stereo. At the core of our techniques is the assumption that the BRDF at each pixel lies in the non-negative span of a known BRDF dictionary. This assumption enables a per-pixel surface normal and BRDF estimation framework that is computationally tractable and requires no initialization in spite of the underlying problem being non-convex. Our estimation framework first solves for the surface normal at each pixel using a variant of example-based photometric stereo. We design an efficient multi-scale search strategy for estimating the surface normal and subsequently, refine this estimate using a gradient descent procedure. Given the surface normal estimate, we solve for the spatially-varying BRDF by constraining the BRDF at each pixel to be in the span of the BRDF dictionary; here, we use additional priors to further regularize the solution. A hallmark of our approach is that it does not require iterative optimization techniques nor the need for careful initialization, both of which are endemic to most state-of-the-art techniques. We showcase the performance of our technique on a wide range of simulated and real scenes where we outperform competing methods.

  15. The effect of vitamin C at varying times on physiological parameters in rabbits after xylazine anaesthesia

    Directory of Open Access Journals (Sweden)

    Godwin Onyeamaechi Egwu

    2011-01-01

    Full Text Available The effects of vitamin C administration at varying time intervals on rectal temperature, respiratory rates, heart rates and sleeping time following xylazine anaesthesia was evaluated in rabbits. A total of 36 rabbits placed in six groups(A-F with 6 animals per group each were used. Groups A and B were used as controls for vitamin C (120 mg/kg, oral and xylazine (4 mg/kg, intramuscular treatments, respectively, while groups C-F received vitamin C at four intervals prior to xylazine anaesthesia. The result of the study showed that vitamin Cpre-medication prior to xylazine anaesthesia induced depression in respiratory and heart rates and a slight increase in rectal temperature. It also significantly increased sleeping time in rabbits (p0.05 in temperature between groups either before or after xylazine administration. It was concluded that vitamin C alters the clinical parameters as well as the sleeping time in rabbits under xylazine anaesthesia.

  16. Varying properties of in situ heat treatment of a tar sands formation based on assessed viscosities

    Energy Technology Data Exchange (ETDEWEB)

    Karanikas, John Michael; Vinegar, Harold J

    2014-03-04

    A method for treating a tar sands formation includes providing heat to at least part of a hydrocarbon layer in the formation from a plurality of heaters located in the formation. The heat is allowed to transfer from the heaters to at least a portion of the formation. A viscosity of one or more zones of the hydrocarbon layer is assessed. The heating rates in the zones are varied based on the assessed viscosities. The heating rate in a first zone of the formation is greater than the heating rate in a second zone of the formation if the viscosity in the first zone is greater than the viscosity in the second zone. Fluids are produced from the formation through the production wells.

  17. Varying total population enhances disease persistence: Qualitative analysis on a diffusive SIS epidemic model

    Science.gov (United States)

    Li, Huicong; Peng, Rui; Wang, Feng-Bin

    2017-01-01

    This paper performs qualitative analysis on an SIS epidemic reaction-diffusion system with a linear source in spatially heterogeneous environment. The main feature of our model lies in that its total population number varies, compared to its counterpart proposed by Allen et al. [2]. The uniform bounds of solutions are derived, based on which, the threshold dynamics in terms of the basic reproduction number is established and the global stability of the unique endemic equilibrium is discussed when spatial environment is homogeneous. In particular, the asymptotic profile of endemic equilibria is determined if the diffusion rate of the susceptible or infected population is small or large. The theoretical results show that a varying total population can enhance persistence of infectious disease, and therefore the disease becomes more threatening and harder to control.

  18. Convergence Analysis of Saddle Point Problems in Time Varying Wireless Systems - Control Theoretical Approach

    CERN Document Server

    Chen, Junting

    2011-01-01

    Saddle point problems arise from many wireless applications, and primal-dual iterative algorithms are widely applied to find the saddle points. In the existing literature, the convergence results of such algorithms are established assuming the problem specific parameters remain unchanged during the iterations. However, this assumption is unrealistic in time varying wireless systems, as explicit message passing is usually involved in the iterations and the channel state information (CSI) may change in a time scale comparable to the algorithm update period. This paper investigates the convergence behavior and the tracking error of primal-dual iterative algorithms under time varying CSI. The convergence results are established by studying the stability of an equivalent virtual dynamic system derived in the paper, and the Lyapunov theory is applied for the stability analysis. We show that the average tracking error is proportional to the time variation rate of the CSI. Based on these analyses, we also derive an a...

  19. New exponential synchronization criteria for time-varying delayed neural networks with discontinuous activations.

    Science.gov (United States)

    Cai, Zuowei; Huang, Lihong; Zhang, Lingling

    2015-05-01

    This paper investigates the problem of exponential synchronization of time-varying delayed neural networks with discontinuous neuron activations. Under the extended Filippov differential inclusion framework, by designing discontinuous state-feedback controller and using some analytic techniques, new testable algebraic criteria are obtained to realize two different kinds of global exponential synchronization of the drive-response system. Moreover, we give the estimated rate of exponential synchronization which depends on the delays and system parameters. The obtained results extend some previous works on synchronization of delayed neural networks not only with continuous activations but also with discontinuous activations. Finally, numerical examples are provided to show the correctness of our analysis via computer simulations. Our method and theoretical results have a leading significance in the design of synchronized neural network circuits involving discontinuous factors and time-varying delays.

  20. Varying negative work assistance at the ankle with a soft exosuit during loaded walking.

    Science.gov (United States)

    Malcolm, Philippe; Lee, Sangjun; Crea, Simona; Siviy, Christopher; Saucedo, Fabricio; Galiana, Ignacio; Panizzolo, Fausto A; Holt, Kenneth G; Walsh, Conor J

    2017-06-26

    Only very recently, studies have shown that it is possible to reduce the metabolic rate of unloaded and loaded walking using robotic ankle exoskeletons. Some studies obtained this result by means of high positive work assistance while others combined negative and positive work assistance. There is no consensus about the isolated contribution of negative work assistance. Therefore, the aim of the present study is to examine the effect of varying negative work assistance at the ankle joint while maintaining a fixed level of positive work assistance with a multi-articular soft exosuit. We tested eight participants during walking at 1.5 ms(-1) with a 23-kg backpack. Participants wore a version of the exosuit that assisted plantarflexion via Bowden cables tethered to an off-board actuation platform. In four active conditions we provided different rates of exosuit bilateral ankle negative work assistance ranging from 0.015 to 0.037 W kg(-1) and a fixed rate of positive work assistance of 0.19 W kg(-1). All active conditions significantly reduced metabolic rate by 11 to 15% compared to a reference condition, where the participants wore the exosuit but no assistance was provided. We found no significant effect of negative work assistance. However, there was a trend (p = .08) toward greater reduction in metabolic rate with increasing negative work assistance, which could be explained by observed reductions in biological ankle and hip joint power and moment. The non-significant trend of increasing negative work assistance with increasing reductions in metabolic rate motivates the value in further studies on the relative effects of negative and positive work assistance. There may be benefit in varying negative work over a greater range or in isolation from positive work assistance.

  1. Reduced Heart Rate Volatility

    Science.gov (United States)

    Grogan, Eric L.; Morris, John A.; Norris, Patrick R.; France, Daniel J.; Ozdas, Asli; Stiles, Renée A.; Harris, Paul A.; Dawant, Benoit M.; Speroff, Theodore

    2004-01-01

    Objective: To determine if using dense data capture to measure heart rate volatility (standard deviation) measured in 5-minute intervals predicts death. Background: Fundamental approaches to assessing vital signs in the critically ill have changed little since the early 1900s. Our prior work in this area has demonstrated the utility of densely sampled data and, in particular, heart rate volatility over the entire patient stay, for predicting death and prolonged ventilation. Methods: Approximately 120 million heart rate data points were prospectively collected and archived from 1316 trauma ICU patients over 30 months. Data were sampled every 1 to 4 seconds, stored in a relational database, linked to outcome data, and de-identified. HR standard deviation was continuously computed over 5-minute intervals (CVRD, cardiac volatility–related dysfunction). Logistic regression models incorporating age and injury severity score were developed on a test set of patients (N = 923), and prospectively analyzed in a distinct validation set (N = 393) for the first 24 hours of ICU data. Results: Distribution of CVRD varied by survival in the test set. Prospective evaluation of the model in the validation set gave an area in the receiver operating curve of 0.81 with a sensitivity and specificity of 70.1 and 80.0, respectively. CVRD predict death as early as 24 hours in the validation set. Conclusions: CVRD identifies a subgroup of patients with a high probability of dying. Death is predicted within first 24 hours of stay. We hypothesize CVRD is a surrogate for autonomic nervous system dysfunction. PMID:15319726

  2. Global Stability of Polytopic Linear Time-Varying Dynamic Systems under Time-Varying Point Delays and Impulsive Controls

    Directory of Open Access Journals (Sweden)

    M. de la Sen

    2010-01-01

    Full Text Available This paper investigates the stability properties of a class of dynamic linear systems possessing several linear time-invariant parameterizations (or configurations which conform a linear time-varying polytopic dynamic system with a finite number of time-varying time-differentiable point delays. The parameterizations may be timevarying and with bounded discontinuities and they can be subject to mixed regular plus impulsive controls within a sequence of time instants of zero measure. The polytopic parameterization for the dynamics associated with each delay is specific, so that (q+1 polytopic parameterizations are considered for a system with q delays being also subject to delay-free dynamics. The considered general dynamic system includes, as particular cases, a wide class of switched linear systems whose individual parameterizations are timeinvariant which are governed by a switching rule. However, the dynamic system under consideration is viewed as much more general since it is time-varying with timevarying delays and the bounded discontinuous changes of active parameterizations are generated by impulsive controls in the dynamics and, at the same time, there is not a prescribed set of candidate potential parameterizations.

  3. Memory for faces and voices varies as a function of sex and expressed emotion.

    Science.gov (United States)

    S Cortes, Diana; Laukka, Petri; Lindahl, Christina; Fischer, Håkan

    2017-01-01

    We investigated how memory for faces and voices (presented separately and in combination) varies as a function of sex and emotional expression (anger, disgust, fear, happiness, sadness, and neutral). At encoding, participants judged the expressed emotion of items in forced-choice tasks, followed by incidental Remember/Know recognition tasks. Results from 600 participants showed that accuracy (hits minus false alarms) was consistently higher for neutral compared to emotional items, whereas accuracy for specific emotions varied across the presentation modalities (i.e., faces, voices, and face-voice combinations). For the subjective sense of recollection ("remember" hits), neutral items received the highest hit rates only for faces, whereas for voices and face-voice combinations anger and fear expressions instead received the highest recollection rates. We also observed better accuracy for items by female expressers, and own-sex bias where female participants displayed memory advantage for female faces and face-voice combinations. Results further suggest that own-sex bias can be explained by recollection, rather than familiarity, rates. Overall, results show that memory for faces and voices may be influenced by the expressions that they carry, as well as by the sex of both items and participants. Emotion expressions may also enhance the subjective sense of recollection without enhancing memory accuracy.

  4. Threshold regression for survival data with time-varying covariates.

    Science.gov (United States)

    Lee, Mei-Ling Ting; Whitmore, G A; Rosner, Bernard A

    2010-03-30

    Time-to-event data with time-varying covariates pose an interesting challenge for statistical modeling and inference, especially where the data require a regression structure but are not consistent with the proportional hazard assumption. Threshold regression (TR) is a relatively new methodology based on the concept that degradation or deterioration of a subject's health follows a stochastic process and failure occurs when the process first reaches a failure state or threshold (a first-hitting-time). Survival data with time-varying covariates consist of sequential observations on the level of degradation and/or on covariates of the subject, prior to the occurrence of the failure event. Encounters with this type of data structure abound in practical settings for survival analysis and there is a pressing need for simple regression methods to handle the longitudinal aspect of the data. Using a Markov property to decompose a longitudinal record into a series of single records is one strategy for dealing with this type of data. This study looks at the theoretical conditions for which this Markov approach is valid. The approach is called threshold regression with Markov decomposition or Markov TR for short. A number of important special cases, such as data with unevenly spaced time points and competing risks as stopping modes, are discussed. We show that a proportional hazards regression model with time-varying covariates is consistent with the Markov TR model. The Markov TR procedure is illustrated by a case application to a study of lung cancer risk. The procedure is also shown to be consistent with the use of an alternative time scale. Finally, we present the connection of the procedure to the concept of a collapsible survival model.

  5. Lichen Persistence and Recovery in Response to Varied Volcanic Disturbances

    Science.gov (United States)

    Nelson, P.; Wheeler, T. B.

    2015-12-01

    Volcanic eruptions produce many ecological disturbances that structure vegetation. While lichens are sensitive to disturbances, little is known about their responses to volcanic disturbances, except for colonization of lava. We examined lichen community responses through time to different disturbances produced by the May 1, 2008 eruption of Volcan Chaiten in south-central Chile. Pre-eruption vegetation near the volcano was old-growth Valdivian temperate rainforest dominated by closed-canopy Nothofagus sp... In 2012, we installed thirteen 1-acre plots across volcanic disturbance zones on which a time-constrained search was done for all macrolichen species, each of which was assigned an approximate log10 categorical abundance. We also installed a 0.2 m2 quadrat on two representative trees per plot for repeat photography of lichen cover. We remeasured at least one plot per disturbance zone in 2014 and re-photographed tree quadrats in 2013 and 2014. We then analyzed species composition and abundance differences among disturbance zones. In 2012, the blast (pyroclastic density flow), scorch (standing scorched forest at the edge of the blast) and deep tephra (>10 cm) zones had the lowest lichen species richness (5-13 species), followed by reference (unimpacted) and shallow (lichen species since 2012 while the light tephra and reference were essentially unchanged. Gravel rain, gravel rain + pumice and flooded forest plots all had about the same number of species in 2014 as 2012. Lichen colonization and growth in tree quadrats varied widely, from very little colonization in the blast to prolific colonization in the gravel rain + pumice zone. Lichen's varied responses to different volcanic disturbances were attributable to varying degrees of mortality and subsequent availability of substrate, quantity of light and removal of competitors. While sensitive to disturbance, lichens are apparently resilient to and can quickly recolonize after a variety of large, violent volcanic

  6. Visual exploration of complex time-varying graphs.

    Science.gov (United States)

    Kumar, Gautam; Garland, Michael

    2006-01-01

    Many graph drawing and visualization algorithms, such as force-directed layout and line-dot rendering, work very well on relatively small and sparse graphs. However, they often produce extremely tangled results and exhibit impractical running times for highly non-planar graphs with large edge density. And very few graph layout algorithms support dynamic time-varying graphs; applying them independently to each frame produces distracting temporally incoherent visualizations. We have developed a new visualization technique based on a novel approach to hierarchically structuring dense graphs via stratification. Using this structure, we formulate a hierarchical force-directed layout algorithm that is both efficient and produces quality graph layouts. The stratification of the graph also allows us to present views of the data that abstract away many small details of its structure. Rather than displaying all edges and nodes at once, resulting in a convoluted rendering, we present an interactive tool that filters edges and nodes using the graph hierarchy and allows users to drill down into the graph for details. Our layout algorithm also accommodates time-varying graphs in a natural way, producing a temporally coherent animation that can be used to analyze and extract trends from dynamic graph data. For example, we demonstrate the use of our method to explore financial correlation data for the U.S. stock market in the period from 1990 to 2005. The user can easily analyze the time-varying correlation graph of the market, uncovering information such as market sector trends, representative stocks for portfolio construction, and the interrelationship of stocks over time.

  7. Acoustic propagation in ducts with varying cross sections

    Science.gov (United States)

    Nayfeh, A. H.; Telionis, D. P.

    1973-01-01

    The method of multiple scales is used to derive the equations that describe the spatial and temporal variation of the amplitudes and phases of a wave packet propagating in slowly varying hard-walled or lined ducts. The analysis is carried out for rectangular as well as circular ducts. These equations are statements of the conservation of energy. For large admittance or high-frequency modes, an approximate expression is obtained for the attenuation. This expression shows that all possible acoustic modes are attenuating. The results also show that decreasing the cross sectional area can lead to elimination of some of the acoustic modes.

  8. Controlling Electricity Consumption by Forecasting its Response to Varying Prices

    DEFF Research Database (Denmark)

    Corradi, Olivier; Ochsenfeld, Henning Peter; Madsen, Henrik

    2013-01-01

    electricity consumption using a one-way price signal. Estimation of the price-response is based on data measurable at grid level, removing the need to install sensors and communication devices between each individual consumer and the price-generating entity. An application for price-responsive heating systems......In a real-time electricity pricing context where consumers are sensitive to varying prices, having the ability to anticipate their response to a price change is valuable. This paper proposes models for the dynamics of such price-response, and shows how these dynamics can be used to control...

  9. Plasma response to a varying degree of stress.

    Science.gov (United States)

    DuBois, Ami M; Thomas, Edward; Amatucci, William E; Ganguli, Gurudas

    2013-10-04

    We report experimental evidence of a seamless transition between three distinct modes in a magnetized plasma with a transverse sheared flow as the ratio of the ion gyroradius to the shear scale length (a measure of shear magnitude) is varied. This was achieved using a dual plasma configuration in a laboratory experiment, where a sheared flow oriented perpendicular to a background magnetic field is localized at the boundary of the plasmas. This confirms the basic theory that plasma is unstable to transverse velocity shear in a broad frequency and wavelength range. The experiment characterizes the compression or relaxation of boundary layers often generated in a variety of laboratory and space plasma processes.

  10. Economic strategies of plant absorptive roots vary with root diameter

    Science.gov (United States)

    Kong, D. L.; Wang, J. J.; Kardol, P.; Wu, H. F.; Zeng, H.; Deng, X. B.; Deng, Y.

    2016-01-01

    Plant roots typically vary along a dominant ecological axis, the root economics spectrum, depicting a tradeoff between resource acquisition and conservation. For absorptive roots, which are mainly responsible for resource acquisition, we hypothesized that root economic strategies differ with increasing root diameter. To test this hypothesis, we used seven plant species (a fern, a conifer, and five angiosperms from south China) for which we separated absorptive roots into two categories: thin roots (thickness of root cortex plus epidermis perspective on our understanding of the root economics spectrum.

  11. Modelling Acoustic Wave Propagation in Axisymmetric Varying-Radius Waveguides

    DEFF Research Database (Denmark)

    Bæk, David; Willatzen, Morten

    2008-01-01

    A computationally fast and accurate model (a set of coupled ordinary differential equations) for fluid sound-wave propagation in infinite axisymmetric waveguides of varying radius is proposed. The model accounts for fluid heat conduction and fluid irrotational viscosity. The model problem is solved...... by expanding solutions in terms of cross-sectional eigenfunctions following Stevenson’s method. A transfer matrix can be easily constructed from simple model responses of a given waveguide and later used in computing the response to any complex wave input. Energy losses due to heat conduction and viscous...

  12. Robust topology optimization accounting for spatially varying manufacturing errors

    DEFF Research Database (Denmark)

    Schevenels, M.; Lazarov, Boyan Stefanov; Sigmund, Ole

    2011-01-01

    This paper presents a robust approach for the design of macro-, micro-, or nano-structures by means of topology optimization, accounting for spatially varying manufacturing errors. The focus is on structures produced by milling or etching; in this case over- or under-etching may cause parts...... optimization problem is formulated in a probabilistic way: the objective function is defined as a weighted sum of the mean value and the standard deviation of the structural performance. The optimization problem is solved by means of a Monte Carlo method: in each iteration of the optimization scheme, a Monte...

  13. Analysis of Linear Time-varying Systems via Haar Wavelet

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    In this paper Haar wavelet integral operational matrices are introduced and the n applied to analyse linear time-varying systems. The method converts the origi nal problem to solving linear algebraic equations. Hence, computational difficulties are considerably reduced. Based on the property of time-frequency localization of Haar wavelet bases, the solution of a system includes both the frequency information and the time information. Other orthogonal functions do not have this property. An example is given, and the results are shown to be ver y accurate.

  14. Reaching a consensus: a discrete nonlinear time-varying case

    Science.gov (United States)

    Saburov, M.; Saburov, K.

    2016-07-01

    In this paper, we have considered a nonlinear protocol for a structured time-varying and synchronous multi-agent system. By means of cubic triple stochastic matrices, we present an opinion sharing dynamics of the multi-agent system as a trajectory of a non-homogeneous system of cubic triple stochastic matrices. We show that the multi-agent system eventually reaches to a consensus if either of the following two conditions is satisfied: (1) every member of the group people has a positive subjective distribution on the given task after some revision steps or (2) all entries of some cubic triple stochastic matrix are positive.

  15. Reduced dielectric response in spatially varying electric fields

    DEFF Research Database (Denmark)

    Hansen, Jesper Schmidt

    2015-01-01

    In this paper, the dynamical equation for polarization is derived. From this the dielectric response to a spatially varying electric field is analyzed showing a reduced response due to flux of polarization in the material. This flux is modeled as a diffusive process through linear constitutive...... relations between the flux and the gradient of the polarization. Comparison between the theory and molecular dynamics simulations confirms this effect. The effect is significant for small length scale electric field variations and the inclusion of the flux is thus important in nanoscale modeling...

  16. Using time-varying covariates in multilevel growth models

    Directory of Open Access Journals (Sweden)

    D. Betsy McCoach

    2010-06-01

    Full Text Available This article provides an illustration of growth curve modeling within a multilevel framework. Specifically, we demonstrate coding schemes that allow the researcher to model discontinuous longitudinal data using a linear growth model in conjunction with time varying covariates. Our focus is on developing a level-1 model that accurately reflects the shape of the growth trajectory. We demonstrate the importance of adequately modeling the shape of the level-1 growth trajectory in order to make inferences about the importance of both level-1 and level-2 predictors.

  17. Signaling Cascades: Consequences of Varying Substrate and Phosphatase Levels

    DEFF Research Database (Denmark)

    Feliu, Elisenda; Knudsen, Michael; Wiuf, Carsten Henrik

    2012-01-01

    We study signaling cascades with an arbitrary number of layers of one-site phosphorylation cycles. Such cascades are abundant in nature and integrated parts of many pathways. Based on the Michaelis-Menten model of enzyme kinetics and the law of mass-action, we derive explicit analytic expressions...... for how the steady state concentrations and the total amounts of substrates, kinase, and phosphatates depend on each other. In particular, we use these to study how the responses (the activated substrates) vary as a function of the available amounts of substrates, kinase, and phosphatases. Our results...

  18. Burstiness and tie reinforcement in time varying social networks

    CERN Document Server

    Ubaldi, Enrico; Karsai, Marton; Perra, Nicola; Burioni, Raffaella

    2016-01-01

    We introduce a time-varying network model accounting for burstiness and tie reinforcement observed in social networks. The analytical solution indicates a non-trivial phase diagram determined by the competition of the leading terms of the two processes. We test our results against numerical simulations, and compare the analytical predictions with an empirical dataset finding good agreements between them. The presented framework can be used to classify the dynamical features of real social networks and to gather new insights about the effects of social dynamics on ongoing spreading processes.

  19. CMB Constraints on Reheating Models with Varying Equation of State

    CERN Document Server

    de Freitas, Rodolfo C

    2015-01-01

    The temperature at the end of reheating and the length of this cosmological phase can be bound to the inflationary observables if one considers the cosmological evolution from the time of Hubble crossing until today. There are many examples in the literature where it is made for single-field inflationary models and a constant equation of state during reheating. We adopt two simple varying equation of state parameters during reheating, combine the allowed range of the reheating parameters with the observational limits of the scalar perturbations spectral index and compare the constraints of some inflationary models with the case of a constant equation of state parameter during reheating.

  20. Varying-$\\alpha $ Theories and Solutions to the Cosmological Problems

    CERN Document Server

    Barrow, John D; Barrow, John D.; Magueijo, Joao

    1998-01-01

    If the fine structure constant $\\alpha =e^2/(\\hbar c)$ were to change, then a number of interpretations would be possible, attributing this change either to variations in the electron charge, the dielectric constant of the vacuum, the speed of light, or Planck's constant. All these variations should be operationally equivalent and can be related by changes of standard units. We show how the varying speed of light cosmology recently proposed can be rephrased as a dielectric vacuum theory, similar to the one proposed by Bekenstein. The cosmological problems will therefore also be solved in such a theory.

  1. Stochastic synchronization for time-varying complex dynamical networks

    Institute of Scientific and Technical Information of China (English)

    Guo Xiao-Yong; Li Jun-Min

    2012-01-01

    This paper studies the stochastic synchronization problem for time-varying complex dynamical networks. This model is totally different from some existing network models. Based on the Lyapunov stability theory, inequality techniques, and the properties of the Weiner process, some controllers and adaptive laws are designed to ensure achieving stochastic synchronization of a complex dynamical network model. A sufficient synchronization condition is given to ensure that the proposed network model is mean-square stable. Theoretical analysis and numerical simulation fully verify the main results.

  2. Generalized multitime expansions for equations with slowly varying coefficients

    Directory of Open Access Journals (Sweden)

    L. E. Levine

    1984-01-01

    Full Text Available The successive terms in a uniformly valid multitime expansion of the solutions of constant coefficient differential equations containing a small parameter ϵ may be obtained without resorting to secularity conditions if the time scales ti=ϵit(i=0,1,… are used. Similar results have been achieved in some cases for equations with variable coefficients by using nonlinear time scales generated from the equations themselves. This paper extends the latter approach to the general second order ordinary differential equation with slowly varying coefficients and examines the restrictions imposed by the method.

  3. Timed arrays wideband and time varying antenna arrays

    CERN Document Server

    Haupt, Randy L

    2015-01-01

    Introduces timed arrays and design approaches to meet the new high performance standards The author concentrates on any aspect of an antenna array that must be viewed from a time perspective. The first chapters briefly introduce antenna arrays and explain the difference between phased and timed arrays. Since timed arrays are designed for realistic time-varying signals and scenarios, the book also reviews wideband signals, baseband and passband RF signals, polarization and signal bandwidth. Other topics covered include time domain, mutual coupling, wideband elements, and dispersion. The auth

  4. Cosmology with Independently Varying Neutrino Temperature and Number

    CERN Document Server

    Galvez, Richard

    2016-01-01

    We consider Big Bang nucleosynthesis and the cosmic microwave background in a model in which both the neutrino temperature and neutrino number are allowed to vary from their standard values. The neutrino temperature is assumed to differ from its standard model value by a given factor from Big Bang nucleosynthesis up to the present. In this scenario, the effective number of relativistic degrees of freedom, $N_{\\rm eff}^{\\rm CMB}$, derived from observations of the cosmic microwave background is not equal to the true number of neutrinos, $N_\

  5. Consumption growth and time-varying expected stock returns

    DEFF Research Database (Denmark)

    Vinther Møller, Stig

    2008-01-01

    When the consumption growth rate is measured based upon fourth quarter data, it tracks predictable variation in future excess stock returns. Low fourth quarter consumption growth rates predict high future excess stock returns such that expected returns are high at business cycle troughs and low...... at business cycle peaks. The consumption growth rate loses predictive power when it is measured based upon other quarters. This is consistent with the insight of Jagannathan and Wang [2007. Journal of Finance 62, 1623-1661] that investors tend to review their consumption and investment plans during the end...... of each calendar year, and at possibly random times in between. The consumption growth rate measured based upon fourth quarter data is a much stronger predictive variable than benchmark predictive variables such as the dividend-price ratio, the term spread, and the default spread....

  6. Analytical treatment of the two-body problem with slowly varying mass

    Science.gov (United States)

    Rahoma, W. A.; Abd El-Salam, F. A.; Ahmed, M. K.

    2009-12-01

    The present work is concerned with the two-body problem with varying mass in case of isotropic mass loss from both components of the binary systems. The law of mass variation used gives rise to a perturbed Keplerian problem depending on two small parameters. The problem is treated analytically in the Hamiltonian frame-work and the equations of motion are integrated using the Lie series developed and applied, separately by Delva (1984) and Hanslmeier (1984). A second order theory of the two bodies eject mass is constructed, returning the terms of the rate of change of mass up to second order in the small parameters of the problem.

  7. Stability Analysis of Cohen-Grossberg Neural Networks with Time-Varying Delays

    Institute of Scientific and Technical Information of China (English)

    LIU Yanqing; TANG Wansheng

    2007-01-01

    The global exponential stability of Cohen-Grossberg neural networks with time-varying delays is studied. By constructing several suitable Lyapunov functionals and utilizing differential inequality techniques, some sufficient criteria for the global exponential stability and the exponential convergence rate of the equilibrium point of the system are obtained. The criteria do not require the activation functions to be differentiable or monotone nondecreasing. Some stability results from previous works are extended and improved. Comparisons are made to demonstrate the advantage of our results.

  8. Charged Particle Tunnels from the Slowly Varying Reissner-Nordstr(o)m Black Hole

    Institute of Scientific and Technical Information of China (English)

    YANG Shu-Zheng; CHEN De-You

    2007-01-01

    Extending Parikh and Wilczek's work to the non-stationary black hole, we discuss the Hawking radiation of the slowly varying Reissner-Nordstr(o)m black hole by considering the unfixed background spacetime and the self-gravitation interaction. The result shows that the tunnelling rate is related to both the variation of Bekenstein-Hawking entropy and the radiation spectrum deviating from the purely thermal one. This is in agreement with Parikh and Wilczek's result. Then a new method to study Hawking radiation of the non-stationary black holes is presented.

  9. Global Stability Analysis for an Internet Congestion Control Model with a Time-Varying Link Capacity

    CERN Document Server

    Rezaie, B; Analoui, M; Khorsandi, S

    2009-01-01

    In this paper, a global stability analysis is given for a rate-based congestion control system modeled by a nonlinear delayed differential equation. The model determines the dynamics of a single-source single-link network, with a time-varying capacity of link and a fixed communication delay. We obtain a sufficient delay-independent conditions on system parameters under which global asymptotic stability of the system is guarantied. The proof is based on an extension of Lyapunov-Krasovskii theorem for a class of nonlinear time-delay systems. The numerical simulations for a typical scenario justify the theoretical results.

  10. Estimation of Semi-Varying Coefficient Model with Surrogate Data and Validation Sampling

    Institute of Scientific and Technical Information of China (English)

    Ya-zhao L(U); Ri-quan ZHANG; Zhen-sheng HUANG

    2013-01-01

    In this paper,we investigate the estimation of semi-varying coefficient models when the nonlinear covariates are prone to measurement error.With the help of validation sampling,we propose two estimators of the parameter and the coefficient functions by combining dimension reduction and the profile likelihood methods without any error structure equation specification or error distribution assumption.We establish the asymptotic normality of proposed estimators for both the parametric and nonparametric parts and show that the proposed estimators achieves the best convergence rate.Data-driven bandwidth selection methods are also discussed.Simulations are conducted to evaluate the finite sample property of the estimation methods proposed.

  11. Variable Selection for Semiparametric Varying-Coefficient Partially Linear Models with Missing Response at Random

    Institute of Scientific and Technical Information of China (English)

    Pei Xin ZHAO; Liu Gen XUE

    2011-01-01

    In this paper,we present a variable selection procedure by combining basis function approximations with penalized estimating equations for semiparametric varying-coefficient partially linear models with missing response at random.The proposed procedure simultaneously selects significant variables in parametric components and nonparametric components.With appropriate selection of the tuning parameters,we establish the consistency of the variable selection procedure and the convergence rate of the regularized estimators.A simulation study is undertaken to assess the finite sample performance of the proposed variable selection procedure.

  12. Analytical Treatment of the Two-Body Problem with Slowly Varying Mass

    Indian Academy of Sciences (India)

    W. A. Rahoma; F. A. Abd El-Salam; M. K. Ahmed

    2009-09-01

    The present work is concerned with the two-body problem with varying mass in case of isotropic mass loss from both components of the binary systems. The law of mass variation used gives rise to a perturbed Keplerian problem depending on two small parameters. The problem is treated analytically in the Hamiltonian frame-work and the equations of motion are integrated using the Lie series developed and applied, separately by Delva (1984) and Hanslmeier (1984). A second order theory of the two bodies eject mass is constructed, returning the terms of the rate of change of mass up to second order in the small parameters of the problem.

  13. Theory of electromagnetic cyclotron wave growth in a time-varying magnetoplasma

    Science.gov (United States)

    Gail, William B.

    1990-01-01

    The effect of a time-dependent perturbation in the magnetoplasma on the wave and particle populations is investigated using the Kennel-Petchek (1966) approach. Perturbations in the cold plasma density, energetic particle distribution, and resonance condition are calculated on the basis of the ideal MHD assumption given an arbitrary compressional magnetic field perturbation. An equation is derived describing the time-dependent growth rate for parallel propagating electromagnetic cyclotron waves in a time-varying magnetoplasma with perturbations superimposed on an equilibrium configuration.

  14. Nuclear Car Wash sensitivity in varying thicknesses of wood and steel cargo

    Energy Technology Data Exchange (ETDEWEB)

    Church, J; Slaughter, D; Asztalos, S; Biltoft, P; Descalle, M; Hall, J; Manatt, D; Mauger, J; Norman, E; Petersen, D; Prussin, S

    2006-10-05

    The influence of incident neutron attenuation on signal strengths in the Nuclear Car Wash has been observed experimentally for both wood and steel-pipe mock cargos. Measured decay curves are presented for {beta}-delayed high-energy {gamma}-rays and thermalized neutrons following neutron-induced fission of HEU through varying irradiation lengths. Error rates are extracted for delayed-{gamma} and delayed-n signals integrated to 30 seconds, assuming Gaussian distributions for the active background. The extrapolation to a field system of 1 mA deuterium current and to a 5 kg sample size is discussed.

  15. Comprehensive proteomic analysis of bovine spermatozoa of varying fertility rates and identification of biomarkers associated with fertility

    Directory of Open Access Journals (Sweden)

    Kaya Abdullah

    2008-02-01

    Full Text Available Abstract Background Male infertility is a major problem for mammalian reproduction. However, molecular details including the underlying mechanisms of male fertility are still not known. A thorough understanding of these mechanisms is essential for obtaining consistently high reproductive efficiency and to ensure lower cost and time-loss by breeder. Results Using high and low fertility bull spermatozoa, here we employed differential detergent fractionation multidimensional protein identification technology (DDF-Mud PIT and identified 125 putative biomarkers of fertility. We next used quantitative Systems Biology modeling and canonical protein interaction pathways and networks to show that high fertility spermatozoa differ from low fertility spermatozoa in four main ways. Compared to sperm from low fertility bulls, sperm from high fertility bulls have higher expression of proteins involved in: energy metabolism, cell communication, spermatogenesis, and cell motility. Our data also suggests a hypothesis that low fertility sperm DNA integrity may be compromised because cell cycle: G2/M DNA damage checkpoint regulation was most significant signaling pathway identified in low fertility spermatozoa. Conclusion This is the first comprehensive description of the bovine spermatozoa proteome. Comparative proteomic analysis of high fertility and low fertility bulls, in the context of protein interaction networks identified putative molecular markers associated with high fertility phenotype.

  16. Performance Evaluation of MANET Routing Protocols under Varying Node Mobility

    Directory of Open Access Journals (Sweden)

    S.Balaji Gupta

    2013-06-01

    Full Text Available Mobile ad hoc network (MANET is an autonomous system containing a cluster of mobile nodes which can dynamically change their network topology. It requires no pre-existing fixed network infrastructureor centralized administration. It operates in a standalone fashion. All the mobile nodes in the network are connected by wireless links. These nodes are free to move anywhere and organize themselves into a network. Each node behaves as a router and should therefore forward packets to other nodes in the network. For this purpose, a routing protocol is needed. Mobile ad-hoc network has certain characteristics such as dynamic topology that inserts new demands on the routing protocol which often limits resources such as storage capacityof CPU, battery power and bandwidth. Mobility models emulate the realistic conditions and dictate the movement of nodes. This paper aims to evaluate the performance and compare the three MANET routingprotocols AODV, DSR and DSDV in different mobility conditions while varying pause time and node density. Three mobility models included are Random Waypoint, Random Walk and Random Direction. Lastly, wepresent simulation results that illustrate how the performance of a MANET protocols drastically change, as a result of changing the mobility taking Throughput, Average End-End Delay, Packet Delivery Ratio and Normalized Routing Load as differentials. The conclusion, which routing protocol is best in each of the varying mobility is also stated. Simulations are carried out using Ns2.

  17. Study of selected phenotype switching strategies in time varying environment

    Energy Technology Data Exchange (ETDEWEB)

    Horvath, Denis, E-mail: horvath.denis@gmail.com [Centre of Interdisciplinary Biosciences, Institute of Physics, Faculty of Science, P.J. Šafárik University in Košice, Jesenná 5, 040 01 Košice (Slovakia); Brutovsky, Branislav, E-mail: branislav.brutovsky@upjs.sk [Department of Biophysics, Institute of Physics, P.J. Šafárik University in Košice, Jesenná 5, 040 01 Košice (Slovakia)

    2016-03-22

    Population heterogeneity plays an important role across many research, as well as the real-world, problems. The population heterogeneity relates to the ability of a population to cope with an environment change (or uncertainty) preventing its extinction. However, this ability is not always desirable as can be exemplified by an intratumor heterogeneity which positively correlates with the development of resistance to therapy. Causation of population heterogeneity is therefore in biology and medicine an intensively studied topic. In this paper the evolution of a specific strategy of population diversification, the phenotype switching, is studied at a conceptual level. The presented simulation model studies evolution of a large population of asexual organisms in a time-varying environment represented by a stochastic Markov process. Each organism disposes with a stochastic or nonlinear deterministic switching strategy realized by discrete-time models with evolvable parameters. We demonstrate that under rapidly varying exogenous conditions organisms operate in the vicinity of the bet-hedging strategy, while the deterministic patterns become relevant as the environmental variations are less frequent. Statistical characterization of the steady state regimes of the populations is done using the Hellinger and Kullback–Leibler functional distances and the Hamming distance. - Highlights: • Relation between phenotype switching and environment is studied. • The Markov chain Monte Carlo based model is developed. • Stochastic and deterministic strategies of phenotype switching are utilized. • Statistical measures of the dynamic heterogeneity reveal universal properties. • The results extend to higher lattice dimensions.

  18. Tolerable Time-Varying Overflow on Grass-Covered Slopes

    Directory of Open Access Journals (Sweden)

    Steven A. Hughes

    2015-03-01

    Full Text Available Engineers require estimates of tolerable overtopping limits for grass-covered levees, dikes, and embankments that might experience steady overflow. Realistic tolerance estimates can be used for both resilient design and risk assessment. A simple framework is developed for estimating tolerable overtopping on grass-covered slopes caused by slowly-varying (in time overtopping discharge (e.g., events like storm surges or river flood waves. The framework adapts the well-known Hewlett curves of tolerable limiting velocity as a function of overflow duration. It has been hypothesized that the form of the Hewlett curves suggests that the grass erosion process is governed by the flow work on the slope above a critical threshold velocity (referred to as excess work, and the tolerable erosional limit is reached when the cumulative excess work exceeds a given value determined from the time-dependent Hewlett curves. The cumulative excess work is expressed in terms of overflow discharge above a critical discharge that slowly varies in time, similar to a discharge hydrograph. The methodology is easily applied using forecast storm surge hydrographs at specific locations where wave action is minimal. For preliminary planning purposes, when storm surge hydrographs are unavailable, hypothetical equations for the water level and overflow discharge hydrographs are proposed in terms of the values at maximum overflow and the total duration of overflow. An example application is given to illustrate use of the methodology.

  19. Variational denoising of partly textured images by spatially varying constraints.

    Science.gov (United States)

    Gilboa, Guy; Sochen, Nir; Zeevi, Yehoshua Y

    2006-08-01

    Denoising algorithms based on gradient dependent regularizers, such as nonlinear diffusion processes and total variation denoising, modify images towards piecewise constant functions. Although edge sharpness and location is well preserved, important information, encoded in image features like textures or certain details, is often compromised in the process of denoising. We propose a mechanism that better preserves fine scale features in such denoising processes. A basic pyramidal structure-texture decomposition of images is presented and analyzed. A first level of this pyramid is used to isolate the noise and the relevant texture components in order to compute spatially varying constraints based on local variance measures. A variational formulation with a spatially varying fidelity term controls the extent of denoising over image regions. Our results show visual improvement as well as an increase in the signal-to-noise ratio over scalar fidelity term processes. This type of processing can be used for a variety of tasks in partial differential equation-based image processing and computer vision, and is stable and meaningful from a mathematical viewpoint.

  20. Holistic gaze strategy to categorize facial expression of varying intensities.

    Directory of Open Access Journals (Sweden)

    Kun Guo

    Full Text Available Using faces representing exaggerated emotional expressions, recent behaviour and eye-tracking studies have suggested a dominant role of individual facial features in transmitting diagnostic cues for decoding facial expressions. Considering that in everyday life we frequently view low-intensity expressive faces in which local facial cues are more ambiguous, we probably need to combine expressive cues from more than one facial feature to reliably decode naturalistic facial affects. In this study we applied a morphing technique to systematically vary intensities of six basic facial expressions of emotion, and employed a self-paced expression categorization task to measure participants' categorization performance and associated gaze patterns. The analysis of pooled data from all expressions showed that increasing expression intensity would improve categorization accuracy, shorten reaction time and reduce number of fixations directed at faces. The proportion of fixations and viewing time directed at internal facial features (eyes, nose and mouth region, however, was not affected by varying levels of intensity. Further comparison between individual facial expressions revealed that although proportional gaze allocation at individual facial features was quantitatively modulated by the viewed expressions, the overall gaze distribution in face viewing was qualitatively similar across different facial expressions and different intensities. It seems that we adopt a holistic viewing strategy to extract expressive cues from all internal facial features in processing of naturalistic facial expressions.

  1. Dynamics of prolate spheroidal mass distributions with varying eccentricity

    CERN Document Server

    Rathulnath, R

    2013-01-01

    In this paper we calculate the potential for a prolate spheroidal distribution as in a dark matter halo with a radially varying eccentricity. This is obtained by summing up the shell-by-shell contributions of isodensity surfaces, which are taken to be concentric and with a common polar axis and with an axis ratio that varies with radius. Interestingly, the constancy of potential inside a shell is shown to be a good approximation even when the isodensity contours are dissimilar spheroids, as long as the radial variation in eccentricity is small as seen in realistic systems. We consider three cases where the isodensity contours are more prolate at large radii, or are less prolate, or have a constant eccentricity. Other relevant physical quantities like the rotation velocity, the net orbital and vertical frequency due to the halo and an exponential disc of finite thickness embedded in it are obtained. We apply this to the kinematical origin of Galactic warp, and show that a prolate shaped halo is not conducive t...

  2. Budgerigar flight in a varying environment: flight at distinct speeds?

    Science.gov (United States)

    Schiffner, Ingo; Srinivasan, Mandyam V

    2016-06-01

    How do flying birds respond to changing environments? The behaviour of budgerigars, Melopsittacus undulatus, was filmed as they flew through a tapered tunnel. Unlike flying insects-which vary their speed progressively and continuously by holding constant the optic flow induced by the walls-the birds showed a tendency to fly at only two distinct, fixed speeds. They switched between a high speed in the wider section of the tunnel, and a low speed in the narrower section. The transition between the two speeds was abrupt, and anticipatory. The high speed was close to the energy-efficient, outdoor cruising speed for these birds, while the low speed was approximately half this value. This is the first observation of the existence of two distinct, preferred flight speeds in birds. A dual-speed flight strategy may be beneficial for birds that fly in varying environments, with the high speed set at an energy-efficient value for flight through open spaces, and the low speed suited to safe manoeuvring in a cluttered environment. The constancy of flight speed within each regime enables the distances of obstacles and landmarks to be directly calibrated in terms of optic flow, thus facilitating simple and efficient guidance of flight through changing environments.

  3. Flexible Demand Management under Time-Varying Prices

    Science.gov (United States)

    Liang, Yong

    In this dissertation, the problem of flexible demand management under time-varying prices is studied. This generic problem has many applications, which usually have multiple periods in which decisions on satisfying demand need to be made, and prices in these periods are time-varying. Examples of such applications include multi-period procurement problem, operating room scheduling, and user-end demand scheduling in the Smart Grid, where the last application is used as the main motivating story throughout the dissertation. The current grid is experiencing an upgrade with lots of new designs. What is of particular interest is the idea of passing time-varying prices that reflect electricity market conditions to end users as incentives for load shifting. One key component, consequently, is the demand management system at the user-end. The objective of the system is to find the optimal trade-off between cost saving and discomfort increment resulted from load shifting. In this dissertation, we approach this problem from the following aspects: (1) construct a generic model, solve for Pareto optimal solutions, and analyze the robust solution that optimizes the worst-case payoffs, (2) extend to a distribution-free model for multiple types of demand (appliances), for which an approximate dynamic programming (ADP) approach is developed, and (3) design other efficient algorithms for practical purposes of the flexible demand management system. We first construct a novel multi-objective flexible demand management model, in which there are a finite number of periods with time-varying prices, and demand arrives in each period. In each period, the decision maker chooses to either satisfy or defer outstanding demand to minimize costs and discomfort over a certain number of periods. We consider both the deterministic model, models with stochastic demand or prices, and when only partial information about the stochastic demand or prices is known. We first analyze the stochastic

  4. 29 CFR 778.403 - Constant pay for varying workweeks including overtime is not permitted except as specified in...

    Science.gov (United States)

    2010-07-01

    ... to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR STATEMENTS OF GENERAL POLICY OR INTERPRETATION NOT DIRECTLY RELATED TO REGULATIONS OVERTIME COMPENSATION Exceptions From the Regular Rate Principles Guaranteed Compensation Which Includes Overtime Pay § 778.403 Constant pay for varying...

  5. Guaranteed Student Loans: Profits of Secondary Market Lenders Vary Widely. United States General Accounting Office Briefing Report to Congressional Requesters.

    Science.gov (United States)

    General Accounting Office, Washington, DC. Div. of Human Resources.

    This report was prepared to determine lenders' rates of return or profitability on Stafford loans in their portfolios, reasons for varying levels of profitability among institutions that hold such loans, and the effect of 1986 subsidy reductions on these lenders' profitability. The study focused on the activities of lenders that purchase Stafford…

  6. Real-time Kalman filter implementation for active feedforward control of time-varying broadband noise and vibrations

    NARCIS (Netherlands)

    Ophem, S. van; Berkhoff, A.P.

    2012-01-01

    Tracking behavior and the rate of convergence are critical properties in active noise control applications with time-varying disturbance spectra. As compared to the standard filtered-reference Least Mean Square (LMS) algorithm, improved convergence can be obtained with schemes based on preconditioni

  7. Active control of time-varying broadband noise and vibrations using a sliding-window Kalman filter

    NARCIS (Netherlands)

    van Ophem, S.; Berkhoff, Arthur P.; Sas, P; Moens, D.; Denayer, H.

    2014-01-01

    Recently, a multiple-input/multiple-output Kalman filter technique was presented to control time-varying broadband noise and vibrations. By describing the feed-forward broadband active noise control problem in terms of a state estimation problem it was possible to achieve a faster rate of

  8. Real-time Kalman filter implementation for active feedforward control of time-varying broadband noise and vibrations

    NARCIS (Netherlands)

    Ophem, S. van; Berkhoff, A.P.

    2012-01-01

    Tracking behavior and the rate of convergence are critical properties in active noise control applications with time-varying disturbance spectra. As compared to the standard filtered-reference Least Mean Square (LMS) algorithm, improved convergence can be obtained with schemes based on

  9. Study on one-dimensional consolidation of soil under cyclic loading and with varied compressibility

    Institute of Scientific and Technical Information of China (English)

    ZHUANG Ying-chun; XIE Kang-he

    2005-01-01

    This paper presents a semi-analytical method to solve one dimensional consolidation problem by taking consideration of varied compressibility of soil under cyclic loading. In the method, soil stratum is divided equally into n layers while load and consolidation time are also divided into small parts and time intervals accordingly. The problem of one-dimensional consolidation of soil stratum under cyclic loading can then be dealt with at each time interval as one-dimensional linear consolidation of multi-layered soils under constant loading. The compression or rebounding of each soil layer can be judged by the effective stress of the layer. When the effective stress is larger than that in the last time interval, the soil layer is compressed, and when it is smaller, the soil layer rebounds. Thus, appropriate compressibility can be chosen and the consolidation of the layered system can be analyzed by the available analytical linear consolidation theory. Based on the semi-analytical method, a computer program was developed and the behavior of one-dimensional consolidation of soil with varied compressibility under cyclic loading was investigated, and compared with the available consolidation theory which takes no consideration of varied compressibility of soil under cyclic loading. The results showed that by taking the variable compressibility into account, the rate of consolidation of soil was greater than the one predicted by conventional consolidation theory.

  10. Sieve M-estimation for semiparametric varying-coefficient partially linear regression model

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    This article considers a semiparametric varying-coefficient partially linear regression model.The semiparametric varying-coefficient partially linear regression model which is a generalization of the partially linear regression model and varying-coefficient regression model that allows one to explore the possibly nonlinear effect of a certain covariate on the response variable.A sieve M-estimation method is proposed and the asymptotic properties of the proposed estimators are discussed.Our main object is to estimate the nonparametric component and the unknown parameters simultaneously.It is easier to compute and the required computation burden is much less than the existing two-stage estimation method.Furthermore,the sieve M-estimation is robust in the presence of outliers if we choose appropriate ρ(·).Under some mild conditions,the estimators are shown to be strongly consistent;the convergence rate of the estimator for the unknown nonparametric component is obtained and the estimator for the unknown parameter is shown to be asymptotically normally distributed.Numerical experiments are carried out to investigate the performance of the proposed method.

  11. Morphology of Rain Water Channeling in Systematically Varied Model Sandy Soils

    Science.gov (United States)

    Wei, Yuli; Cejas, Cesare M.; Barrois, Rémi; Dreyfus, Rémi; Durian, Douglas J.

    2014-10-01

    We visualize the formation of fingered flow in dry model sandy soils under different rain conditions using a quasi-2D experimental setup and systematically determine the impact of the soil grain diameter and surface wetting properties on the water channeling phenomenon. The model sandy soils we use are random closely packed glass beads with varied diameters and surface treatments. For hydrophilic sandy soils, our experiments show that rain water infiltrates a shallow top layer of soil and creates a horizontal water wetting front that grows downward homogeneously until instabilities occur to form fingered flows. For hydrophobic sandy soils, in contrast, we observe that rain water ponds on the top of the soil surface until the hydraulic pressure is strong enough to overcome the capillary repellency of soil and create narrow water channels that penetrate the soil packing. Varying the raindrop impinging speed has little influence on water channel formation. However, varying the rain rate causes significant changes in the water infiltration depth, water channel width, and water channel separation. At a fixed rain condition, we combine the effects of the grain diameter and surface hydrophobicity into a single parameter and determine its influence on the water infiltration depth, water channel width, and water channel separation. We also demonstrate the efficiency of several soil water improvement methods that relate to the rain water channeling phenomenon, including prewetting sandy soils at different levels before rainfall, modifying soil surface flatness, and applying superabsorbent hydrogel particles as soil modifiers.

  12. Coded throughput performance simulations for the time-varying satellite channel. M.S. Thesis

    Science.gov (United States)

    Han, LI

    1995-01-01

    The design of a reliable satellite communication link involving the data transfer from a small, low-orbit satellite to a ground station, but through a geostationary satellite, was examined. In such a scenario, the received signal power to noise density ratio increases as the transmitting low-orbit satellite comes into view, and then decreases as it then departs, resulting in a short-duration, time-varying communication link. The optimal values of the small satellite antenna beamwidth, signaling rate, modulation scheme and the theoretical link throughput (in bits per day) have been determined. The goal of this thesis is to choose a practical coding scheme which maximizes the daily link throughput while satisfying a prescribed probability of error requirement. We examine the throughput of both fixed rate and variable rate concatenated forward error correction (FEC) coding schemes for the additive white Gaussian noise (AWGN) channel, and then examine the effect of radio frequency interference (RFI) on the best coding scheme among them. Interleaving is used to mitigate degradation due to RFI. It was found that the variable rate concatenated coding scheme could achieve 74 percent of the theoretical throughput, equivalent to 1.11 Gbits/day based on the cutoff rate R(sub 0). For comparison, 87 percent is achievable for AWGN-only case.

  13. Effects of Varying the Three-Body Molecular Hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Turk, Matthew J.; /San Diego, CASS; Clark, Paul; Glover, S.C.O.; /ZAH, Heidelberg; Greif, T.H.; /Garching, Max Planck Inst. Plasmaphys.; Abel, Tom; Klessen, Ralf; /KIPAC, Menlo Park /ZAH, Heidelberg /KIPAC, Menlo Park; Bromm, Volker; /Texas U., Astron. Dept.

    2011-03-03

    The transformation of atomic hydrogen to molecular hydrogen through three-body reactions is a crucial stage in the collapse of primordial, metal-free halos, where the first generation of stars (Population III stars) in the Universe are formed. However, in the published literature, the rate coefficient for this reaction is uncertain by nearly an order of magnitude. We report on the results of both adaptive mesh refinement (AMR) and smoothed particle hydrodynamics (SPH) simulations of the collapse of metal-free halos as a function of the value of this rate coefficient. For each simulation method, we have simulated a single halo three times, using three different values of the rate coefficient. We find that while variation between halo realizations may be greater than that caused by the three-body rate coefficient being used, both the accretion physics onto Population III protostars as well as the long-term stability of the disk and any potential fragmentation may depend strongly on this rate coefficient.

  14. Effects of Varying the Three-Body Molecular Hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Turk, Matthew J.; /San Diego, CASS; Clark, Paul; Glover, S.C.O.; /ZAH, Heidelberg; Greif, T.H.; /Garching, Max Planck Inst. Plasmaphys.; Abel, Tom; Klessen, Ralf; /KIPAC, Menlo Park /ZAH, Heidelberg /KIPAC, Menlo Park; Bromm, Volker; /Texas U., Astron. Dept.

    2011-03-03

    The transformation of atomic hydrogen to molecular hydrogen through three-body reactions is a crucial stage in the collapse of primordial, metal-free halos, where the first generation of stars (Population III stars) in the Universe are formed. However, in the published literature, the rate coefficient for this reaction is uncertain by nearly an order of magnitude. We report on the results of both adaptive mesh refinement (AMR) and smoothed particle hydrodynamics (SPH) simulations of the collapse of metal-free halos as a function of the value of this rate coefficient. For each simulation method, we have simulated a single halo three times, using three different values of the rate coefficient. We find that while variation between halo realizations may be greater than that caused by the three-body rate coefficient being used, both the accretion physics onto Population III protostars as well as the long-term stability of the disk and any potential fragmentation may depend strongly on this rate coefficient.

  15. A hierarchical nest survival model integrating incomplete temporally varying covariates

    Science.gov (United States)

    Converse, Sarah J.; Royle, J. Andrew; Adler, Peter H.; Urbanek, Richard P.; Barzan, Jeb A.

    2013-01-01

    Nest success is a critical determinant of the dynamics of avian populations, and nest survival modeling has played a key role in advancing avian ecology and management. Beginning with the development of daily nest survival models, and proceeding through subsequent extensions, the capacity for modeling the effects of hypothesized factors on nest survival has expanded greatly. We extend nest survival models further by introducing an approach to deal with incompletely observed, temporally varying covariates using a hierarchical model. Hierarchical modeling offers a way to separate process and observational components of demographic models to obtain estimates of the parameters of primary interest, and to evaluate structural effects of ecological and management interest. We built a hierarchical model for daily nest survival to analyze nest data from reintroduced whooping cranes (Grus americana) in the Eastern Migratory Population. This reintroduction effort has been beset by poor reproduction, apparently due primarily to nest abandonment by breeding birds. We used the model to assess support for the hypothesis that nest abandonment is caused by harassment from biting insects. We obtained indices of blood-feeding insect populations based on the spatially interpolated counts of insects captured in carbon dioxide traps. However, insect trapping was not conducted daily, and so we had incomplete information on a temporally variable covariate of interest. We therefore supplemented our nest survival model with a parallel model for estimating the values of the missing insect covariates. We used Bayesian model selection to identify the best predictors of daily nest survival. Our results suggest that the black fly Simulium annulus may be negatively affecting nest survival of reintroduced whooping cranes, with decreasing nest survival as abundance of S. annulus increases. The modeling framework we have developed will be applied in the future to a larger data set to evaluate the

  16. TIME-VARYING COEFFICIENT TAYLOR RULE AND CHINESE MONETARY POLICY: EVIDENCE FROM THE TIME-VARYING COINTEGRATION

    National Research Council Canada - National Science Library

    Yu Guo; Wei Ma

    2016-01-01

    .... China is a transition economy, undergoing gradual reform. Consequently, the fixed coefficient cointegration approach is unable to capture the long-run relationship among interest rate, inflation gap, and output gap...

  17. A New Adaptive Channel Estimation for Frequency Selective Time Varying Fading OFDM Channels

    CERN Document Server

    Afifi, Wessam M

    2010-01-01

    In this paper a new algorithm for adaptive dynamic channel estimation for frequency selective time varying fading OFDM channels is proposed. The new algorithm adopts a new strategy that successfully increases OFDM symbol rate. Instead of using a fixed training pilot sequence, the proposed algorithm uses a logic controller to choose among several available training patterns. The controller choice is based on the cross-correlation between pilot symbols over two consecutive time instants (which is considered to be a suitable measure of channel stationarity) as well as the deviation from the desired BER. Simulation results of the system performance confirm the effectiveness of this new channel estimation technique over traditional non-adaptive estimation methods in increasing the data rate of OFDM symbols while maintaining the same probability of error.

  18. Effects of varying surfactant chain lengths on the magnetic, optical and hyperthermia properties of ferrofluids

    Science.gov (United States)

    Rablau, Corneliu; Vaishnava, Prem; Regmi, Rajesh; Sudakar, Chandran; Black, Correy; Lawes, Gavin; Naik, Ratna; Lavoie, Melissa; Kahn, David

    2009-03-01

    We report studies of the structural, magnetic, magneto-thermal and magneto-optic properties of dextran, oleic acid, lauric acid and myristic acid surfacted Fe3O4 nanoparticles of hydrodynamic sizes ranging from 32 nm to 92 nm. All the samples showed saturation magnetization of ˜50 emu/g, significantly smaller than the bulk value for Fe3O4, together with superparamagnetic behavior. The ac magnetization measurements on the dextran coated nanoparticles showed frequency dependent blocking temperature, consistent with superparamgnetic blocking. The ferrofluid heating rates in a 250 Gauss, 100 kHz ac magnetic field varied with the chain lengths of the surfactants, with higher heating rates for longer chains. DC-magnetic-field-induced light scattering patterns produced by two orthogonal He-Ne laser beams passing through the ferrofluid sample revealed different optical signatures for different surfactants.

  19. The performance of the backpropagation algorithm with varying slope of the activation function

    Energy Technology Data Exchange (ETDEWEB)

    Bai Yanping [National Key Laboratory of Micro/Nano Fabrication Technology, Institute of Microelectronics, Peking University, 100871 (China); Department of Applied Mathematics, North University of China, No. 3 Xueyuan Road, TaiYuan, ShanXi 030051 (China)], E-mail: baiyp@nuc.edu.cn; Zhang Haixia [National Key Laboratory of Micro/Nano Fabrication Technology, Institute of Microelectronics, Peking University, 100871 (China); Hao Yilong [National Key Laboratory of Micro/Nano Fabrication Technology, Institute of Microelectronics, Peking University, 100871 (China)], E-mail: yilonghao@ime.pke.edu.cn

    2009-04-15

    Some adaptations are proposed to the basic BP algorithm in order to provide an efficient method to non-linear data learning and prediction. In this paper, an adopted BP algorithm with varying slope of activation function and different learning rates is put forward. The results of experiment indicated that this algorithm can get very good performance of training. We also test the prediction performance of our adopted BP algorithm on 16 instances. We compared the test results to the ones of the BP algorithm with gradient descent momentum and an adaptive learning rate. The results indicate this adopted BP algorithm gives best performance (100%) for test example, which conclude this adopted BP algorithm produces a smoothed reconstruction that learns better to new prediction function values than the BP algorithm improved with momentum.

  20. Varied definitions of risk related to sensation seeking trait

    Energy Technology Data Exchange (ETDEWEB)

    Daastoel, P.Oe.U.; Drottz-Sjoeberg, B.M. [Norwegian Univ. of Science and Technology, Trondheim (Norway). Dept. of Psychology

    1999-12-01

    This pilot study is based on the assumption and the knowledge that previous results show that the normal use of the word risk varies across subjects. The risk definitions the subjects use have also been shown to be related to various educational interests. A related field of research has developed measures for Sensation Seeking personality trait, with four facets. Three independent groups of first year psychology students reported their normal definition of the word risk using one of three measurement formats. The results showed, e.g. that the typical open-ended response to the personal definition of risk was danger. Subjects who defined risk as the combination of probability and consequences tended to score higher on the total Sensation Seeking Scale, as compared to those defining risk as the probability of an event.