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Sample records for attenuation physics

  1. Physical and biogeochemical controls on light attenuation in a eutrophic, back-barrier estuary

    Science.gov (United States)

    Ganju, Neil K.; Miselis, Jennifer L.; Aretxabaleta, Alfredo L.

    2014-01-01

    Light attenuation is a critical parameter governing the ecological function of shallow estuaries. In these systems primary production is often dominated by benthic macroalgae and seagrass; thus light penetration to the bed is of primary importance. We quantified light attenuation in three seagrass meadows in Barnegat Bay, New Jersey, a shallow eutrophic back-barrier estuary; two of the sites were located within designated Ecologically Sensitive Areas (ESAs). We sequentially deployed instrumentation measuring photosynthetically active radiation, chlorophyll-a (chl-a) fluorescence, dissolved organic matter fluorescence (fDOM; a proxy for colored DOM absorbance), turbidity, pressure, and water velocity at 10 min intervals over three week periods at each site. At the southernmost site, where sediment availability was highest, light attenuation was highest and dominated by turbidity and to a lesser extent chl-a and CDOM. At the central site, chl-a dominated followed by turbidity and CDOM, and at the northernmost site turbidity and CDOM contributed equally to light attenuation. At a given site, the temporal variability of light attenuation exceeded the difference in median light attenuation at the three sites, indicating the need for continuous high-temporal resolution measurements. Vessel wakes, anecdotally implicated in increasing sediment resuspension, did not contribute to local resuspension within the seagrass beds, though frequent vessel wakes were observed in the channels. With regards to light attenuation and water clarity, physical and biogeochemical variables appear to outweigh any regulation of boat traffic within the ESAs.

  2. Does physical activity attenuate, or even eliminate, the detrimental association of sitting time with mortality?

    DEFF Research Database (Denmark)

    Ekelund, Ulf; Steene-Johannessen, Jostein; Brown, Wendy J

    2016-01-01

    BACKGROUND: High amounts of sedentary behaviour have been associated with increased risks of several chronic conditions and mortality. However, it is unclear whether physical activity attenuates or even eliminates the detrimental effects of prolonged sitting. We examined the associations of seden......BACKGROUND: High amounts of sedentary behaviour have been associated with increased risks of several chronic conditions and mortality. However, it is unclear whether physical activity attenuates or even eliminates the detrimental effects of prolonged sitting. We examined the associations...... of sedentary behaviour and physical activity with all-cause mortality. METHODS: We did a systematic review, searching six databases (PubMed, PsycINFO, Embase, Web of Science, Sport Discus, and Scopus) from database inception until October, 2015, for prospective cohort studies that had individual level exposure...

  3. Physical Activity Attenuates the Influence of FTO Variants on Obesity Risk

    DEFF Research Database (Denmark)

    Oskari Kilpeläinen, Tuomas; Qi, Lu; Brage, Soren

    2011-01-01

    Background The FTO gene harbors the strongest known susceptibility locus for obesity. While many individual studies have suggested that physical activity (PA) may attenuate the effect of FTO on obesity risk, other studies have not been able to confirm this interaction. To confirm or refute......>0.8]) and PA were invited to participate, regardless of ethnicity or age of the participants. PA was standardized by categorizing it into a dichotomous variable (physically inactive versus active) in each study. Overall, 25% of adults and 13% of children were categorized as inactive. Interaction analyses were.......20–1.26), but PA attenuated this effect (pinteraction = 0.001). More specifically, the minor allele of rs9939609 increased the odds of obesity less in the physically active group (odds ratio = 1.22/allele, 95% CI 1.19–1.25) than in the inactive group (odds ratio = 1.30/allele, 95% CI 1...

  4. Attenuation Model Using the Large-N Array from the Source Physics Experiment

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    Atterholt, J.; Chen, T.; Snelson, C. M.; Mellors, R. J.

    2017-12-01

    The Source Physics Experiment (SPE) consists of a series of chemical explosions at the Nevada National Security Site. SPE seeks to better characterize the influence of subsurface heterogeneities on seismic wave propagation and energy dissipation from explosions. As a part of this experiment, SPE-5, a 5000 kg TNT equivalent chemical explosion, was detonated in 2016. During the SPE-5 experiment, a Large-N array of 996 geophones (half 3-component and half z-component) was deployed. This array covered an area that includes loosely consolidated alluvium (weak rock) and weathered granite (hard rock), and recorded the SPE-5 explosion as well as 53 weight drops. We use these Large-N recordings to develop an attenuation model of the area to better characterize how geologic structures influence source energy partitioning. We found a clear variation in seismic attenuation for different rock types: high attenuation (low Q) for alluvium and low attenuation (high Q) for granite. The attenuation structure correlates well with local geology, and will be incorporated into the large simulation effort of the SPE program to validate predictive models. (LA-UR-17-26382)

  5. Study characteristics of new concrete mixes and their mechanical, physical, and gamma radiation attenuation features

    Energy Technology Data Exchange (ETDEWEB)

    El-Samrah, Moamen G.; Abdel-Rahman, Mohamed A.E. [Nuclear Engineering Department, Military Technical College Kobry El-kobbah, Cairo (Egypt); Kany, Amr M.I. [Physics Department, Faculty of Science, Al-Azhar University, Cairo (Egypt)

    2018-02-01

    Ordinary concrete and those of different compositions are regarded as suitable material in many applications concerning with gamma and neutron radiation shielding purposes. They are widely used in nuclear power plant, medical facilities, nuclear shelters, and for radioactive materials transportation as well as storage of radioactive wastes. In this study four different concrete mixes were prepared with the following different types of coarse aggregates: dolomite, barite, goethite, and steel slag. The effect of changes in the fine aggregates, selected to be 50 % local sand and 50 % limonite with addition of 10 % silica fume (SF) and 10 % fly ash (FA) by replacement of the total cement weight, on the performance of the samples was also investigated. To examine the performance of such samples for radiation shielding applications, a set of physical, mechanical, and radiation attenuation properties was studied and compared with those of ordinary concrete. This investigation includes compressive strength, slump test, bulk density, ultrasonic pulse velocity test, and gamma rays attenuation measurements for the different samples. A verification of the experimental results concerning the radiation attenuation measurements was performed using WinXcom program (Version 3.1). The experimental results revealed that all concrete mixes; goethite-limonite concrete (G.L), barite-limonite concrete (B.L), steel slag-limonite concrete (S.L) and dolomite concrete (D.C) have good physical and mechanical properties that successfully satisfying them as high performance concretes. In addition the barite-limonite and the steel slag-limonite have the higher γ-ray attenuation coefficients at low and high energy range and hence have a better radiation shielding. The obtained results from WinXcom program calculations showed a good agreement with the experimental results concerning γ-ray attenuation measurements for the studied concrete mixes. (copyright 2018 WILEY-VCH Verlag GmbH and Co. KGa

  6. Physical Activity Attenuates Total and Cardiovascular Mortality Associated With Physical Disability: A National Cohort of Older Adults.

    Science.gov (United States)

    Martinez-Gomez, David; Guallar-Castillon, Pilar; Higueras-Fresnillo, Sara; Garcia-Esquinas, Esther; Lopez-Garcia, Esther; Bandinelli, Stefania; Rodríguez-Artalejo, Fernando

    2018-01-16

    Regular physical activity (PA) has been shown to protect against disability onset but, once the disability is present, it is unclear if PA might attenuate its harmful health consequences. Thus, we examined if mortality risk associated with physical disability can be offset by PA among older adults. We used data from a cohort of 3,752 individuals representative of the noninstitutionalized population aged 60 years and older in Spain. In 2000-2001, participants self-reported both PA levels (inactive, occasionally, monthly, weekly) and five physical disabilities (agility, mobility, global daily activities, instrumental activities of daily living, and self-care). Individuals were prospectively followed through 2014 to assess incident deaths. The mean follow-up was 10.8 years, with a total of 1,727 deaths, 638 of them due to cardiovascular disease (CVD). All disability types were associated with higher total and CVD mortality. Being physically active (ie, doing any PA) was associated with a statistically significant 26%-37% and 35%-50% lower risk of total and CVD death, respectively, across types of disability. As compared with those being physically active and without disability, those who were inactive and had a disability showed the highest mortality risk from total (hazard ratios from 1.52 to 1.90 across disabilities, all p disability. In older adults, PA could attenuate the increased risk of mortality associated with physical disability. © The Author 2017. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  7. Physical activity attenuates age-related biomarker alterations in preclinical AD.

    Science.gov (United States)

    Okonkwo, Ozioma C; Schultz, Stephanie A; Oh, Jennifer M; Larson, Jordan; Edwards, Dorothy; Cook, Dane; Koscik, Rebecca; Gallagher, Catherine L; Dowling, N M; Carlsson, Cynthia M; Bendlin, Barbara B; LaRue, Asenath; Rowley, Howard A; Christian, Brad T; Asthana, Sanjay; Hermann, Bruce P; Johnson, Sterling C; Sager, Mark A

    2014-11-04

    To examine whether engagement in physical activity might favorably alter the age-dependent evolution of Alzheimer disease (AD)-related brain and cognitive changes in a cohort of at-risk, late-middle-aged adults. Three hundred seventeen enrollees in the Wisconsin Registry for Alzheimer's Prevention underwent T1 MRI; a subset also underwent (11)C-Pittsburgh compound B-PET (n = 186) and (18)F-fluorodeoxyglucose-PET (n = 152) imaging. Participants' responses on a self-report measure of current physical activity were used to classify them as either physically active or physically inactive based on American Heart Association guidelines. They also completed a comprehensive neuropsychological battery. Covariate-adjusted regression analyses were used to test whether the adverse effect of age on imaging and cognitive biomarkers was modified by physical activity. There were significant age × physical activity interactions for β-amyloid burden (p = 0.014), glucose metabolism (p = 0.015), and hippocampal volume (p = 0.025) such that, with advancing age, physically active individuals exhibited a lesser degree of biomarker alterations compared with the physically inactive. Similar age × physical activity interactions were also observed on cognitive domains of Immediate Memory (p = 0.042) and Visuospatial Ability (p = 0.016). In addition, the physically active group had higher scores on Speed and Flexibility (p = 0.002) compared with the inactive group. In a middle-aged, at-risk cohort, a physically active lifestyle is associated with an attenuation of the deleterious influence of age on key biomarkers of AD pathophysiology. However, because our observational, cross-sectional design cannot establish causality, randomized controlled trials/longitudinal studies will be necessary for determining whether midlife participation in structured physical exercise forestalls the development of AD and related disorders in later life. © 2014 American Academy of Neurology.

  8. Physical activity attenuates neuropsychiatric disturbances and caregiver burden in patients with dementia

    Directory of Open Access Journals (Sweden)

    Gustavo Christofoletti

    2011-01-01

    Full Text Available INTRODUCTION: A significant benefit from physical activity has recently been described in some patients who suffer from neurodegenerative diseases. OBJECTIVE: To assess the effects of physical activity on neuropsychiatric disturbances in demented patients and on the mental burden of their caregivers. METHODS: Assisted by a public geriatric psychiatry clinical unit, we studied 59 patients with dementia. Patients were divided into three groups according to their diagnosis and level of physical activity. Data were assessed through a semi-structured interview. Patients were evaluated with the Neuropsychiatric Inventory, the Mini-Sleep Questionnaire and the Baecke Questionnaire. The data were statistically analyzed using the Mann-Whitney U test and linear regression, with the level of significance set at 5%. RESULTS: Patients with Alzheimer's or vascular dementia who engaged in physical activity had fewer neuropsychiatric symptoms than those who did not. When compared to the control group, the caregivers of patients with vascular dementia who engaged in physical activity had a reduced burden. CONCLUSION: The regular practice of physical activity seems to contribute to a reduction in neuropsychiatric symptoms in dementia patients and to attenuate the burden of the caregivers of those patients.

  9. Effects of Mental Fatigue on Physical Endurance Performance and Muscle Activation Are Attenuated by Monetary Incentives.

    Science.gov (United States)

    Brown, Denver M Y; Bray, Steven R

    2017-12-01

    Physical performance is impaired following cognitive control exertion. Incentives can ameliorate adverse carryover effects of cognitive control exertion but have not been investigated for physical endurance. This study examined the effect of monetary incentives on physical performance and muscle activation following exposure to a mentally fatiguing, cognitive control task. Participants (N = 82) performed two isometric endurance handgrip trials separated by a 12-min cognitive control manipulation using a 2 (high cognitive control [HCC]/low cognitive control [LCC]) × 2 (incentive/no incentive) design. Mental fatigue was significantly higher in the HCC conditions. Performance decreased in the HCC/no incentive condition but was unaffected in the HCC/incentive condition, which did not differ from the low cognitive control conditions. Electromyography data revealed increased muscle activation in the HCC/no incentive condition, which was also attenuated in the HCC/incentive condition. Findings show that incentives counteract the negative effects of HCC on physical endurance and alter central drive to motor units.

  10. Nature cures nature: Hypericum perforatum attenuates physical withdrawal signs in opium dependent rats.

    Science.gov (United States)

    Khan, Munasib; Subhan, Fazal; Khan, Arif-Ullah; Abbas, Muzaffar; Ali, Gowhar; Rauf, Khalid; Gilani, Anwarul Hassan

    2014-05-01

    Hypericum perforatum Linn. (Hypericaceae) (St. John's wort) attenuates opium withdrawal signs. To explore the therapeutic potential of Hypericum perforatum in the management of opium-induced withdrawal syndrome. The effect of the Hypericum perforatum hydro-ethanol extract was investigated for potential to reverse naloxone (0.25 mg/kg)-induced opium withdrawal physical signs. Rats received opium extract (80-650 mg/kg) twice daily for 8 days along with Hypericum perforatum (20 mg/kg, orally) twice daily in chronic treatment and the same single dose 1 h before induction of withdrawal syndrome in the acute treated group. Hypericum perforatum reduced stereotype jumps and wet dog shake number in the chronic treatment compared to the saline control group (F(2, 24) = 3.968, p opium withdrawal syndrome possibly through direct or indirect interaction with opioid receptors. Further study is needed to clarify its mechanism.

  11. Long-Term Low Intensity Physical Exercise Attenuates Heart Failure Development in Aging Spontaneously Hypertensive Rats

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    Luana U. Pagan

    2015-04-01

    Full Text Available Background: Physical exercise is a strategy to control hypertension and attenuate pressure overload-induced cardiac remodeling. The influence of exercise on cardiac remodeling during uncontrolled hypertension is not established. We evaluated the effects of a long-term low intensity aerobic exercise protocol on heart failure (HF development and cardiac remodeling in aging spontaneously hypertensive rats (SHR. Methods: Sixteen month old SHR (n=50 and normotensive Wistar-Kyoto (WKY, n=35 rats were divided into sedentary (SED and exercised (EX groups. Rats exercised in treadmill at 12 m/min, 30 min/day, 5 days/week, for four months. The frequency of HF features was evaluated at euthanasia. Statistical analyses: ANOVA and Tukey or Mann-Whitney, and Goodman test. Results: Despite slightly higher systolic blood pressure, SHR-EX had better functional capacity and lower HF frequency than SHR-SED. Echocardiography and tissue Doppler imaging showed no differences between SHR groups. In SHR-EX, however, left ventricular (LV systolic diameter, larger in SHR-SED than WKY-SED, and endocardial fractional shortening, lower in SHR-SED than WKY-SED, had values between those in WKY-EX and SHR-SED not differing from either group. Myocardial function, assessed in LV papillary muscles, showed improvement in SHR-EX over SHR-SED and WKY-EX. LV myocardial collagen fraction and type I and III collagen gene expression were increased in SHR groups. Myocardial hydroxyproline concentration was lower in SHR-EX than SHR-SED. Lysyl oxidase gene expression was higher in SHR-SED than WKY-SED. Conclusion: Exercise improves functional capacity and reduces decompensated HF in aging SHR independent of elevated arterial pressure. Improvement in functional status is combined with attenuation of LV and myocardial dysfunction and fibrosis.

  12. Physical activity does not attenuate the obesity risk of TV viewing in youth.

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    Rey-López, J P; Ruiz, J R; Vicente-Rodríguez, G; Gracia-Marco, L; Manios, Y; Sjöström, M; De Bourdeaudhuij, I; Moreno, L A

    2012-06-01

    This study aimed to examine the association of television (TV) time, the frequency of meals while watching TV and the presence of TV set in the bedroom with total and abdominal obesity and to assess whether physical activity (PA) attenuates the obesity risk of TV viewing. Cross-sectional data were obtained from 2200 adolescents (46% boys) from 10 European cities, The Healthy Lifestyle in Europe by Nutrition in Adolescence study, between 2006 and 2007. TV viewing, PA (by accelerometry) and body composition were measured. Binary logistic regression analyses were performed. Even adjusting by vigorous PA, TV in the bedroom (odds ratio [OR]: 1.33, 95% confidence interval [CI], 1.01-1.74) and >4 h d(-1) TV during week days (OR: 1.30, 95% CI, 1.02-1.67) (in boys) and eating every day with TV (OR: 1.18, 95% CI, 1.07-1.30) and >2 h d(-1) TV during weekend days (OR: 1.68, 95% CI, 1.25-2.26) (in girls) were significantly associated with total obesity. Likewise, in both sexes, having a TV set at bedroom was significantly associated with abdominal obesity. Adolescents spending excessive TV time are prone to obesity independently of their PA levels. Families should put TV sets out of adolescents' bedroom and keep TV sets off during meal times. © 2012 The Authors. Pediatric Obesity © 2012 International Association for the Study of Obesity.

  13. Maternal low-protein diet-induced delayed reflex ontogeny is attenuated by moderate physical training during gestation in rats.

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    Falcão-Tebas, Filippe; Bento-Santos, Adriano; Fidalgo, Marco Antônio; de Almeida, Marcelus Brito; dos Santos, José Antônio; Lopes de Souza, Sandra; Manhães-de-Castro, Raul; Leandro, Carol Góis

    2012-02-01

    We evaluated the effects of moderate- to low-intensity physical training during gestation on reflex ontogeny in neonate rats whose mothers were undernourished. Virgin female Wistar rats were divided into four groups as follows: untrained (NT, n 7); trained (T, n 7); untrained with a low-protein diet (NT+LP, n 7); trained with a low-protein diet (T+LP, n 4). Trained rats were subjected to a protocol of moderate physical training on a treadmill over a period of 4 weeks (5 d/week and 60 min/d, at 65 % of VO₂max). After confirming the pregnancy, the intensity and duration of the exercise were reduced. Low-protein groups were provided with an 8 % casein diet, and controls were provided with a 17 % casein diet. Their respective offspring were evaluated (during the 10th-17th days of postnatal life) in terms of physical feature maturation, somatic growth and reflex ontogeny. Pups born to mothers provided with the low-protein diet during gestation and lactation showed delayed physical feature and reflex maturation and a deficit in somatic growth when compared with controls. However, most of these deficiencies were attenuated in pups of undernourished mothers undergoing training. In conclusion, physical training during gestation attenuates the effects of perinatal undernutrition on some patterns of maturation in the central nervous system during development.

  14. Cyber attack analysis on cyber-physical systems: Detectability, severity, and attenuation strategy

    Science.gov (United States)

    Kwon, Cheolhyeon

    Security of Cyber-Physical Systems (CPS) against malicious cyber attacks is an important yet challenging problem. Since most cyber attacks happen in erratic ways, it is usually intractable to describe and diagnose them systematically. Motivated by such difficulties, this thesis presents a set of theories and algorithms for a cyber-secure architecture of the CPS within the control theoretic perspective. Here, instead of identifying a specific cyber attack model, we are focused on analyzing the system's response during cyber attacks. Firstly, we investigate the detectability of the cyber attacks from the system's behavior under cyber attacks. Specifically, we conduct a study on the vulnerabilities in the CPS's monitoring system against the stealthy cyber attack that is carefully designed to avoid being detected by its detection scheme. After classifying three kinds of cyber attacks according to the attacker's ability to compromise the system, we derive the necessary and sufficient conditions under which such stealthy cyber attacks can be designed to cause the unbounded estimation error while not being detected. Then, the analytical design method of the optimal stealthy cyber attack that maximizes the estimation error is developed. The proposed stealthy cyber attack analysis is demonstrated with illustrative examples on Air Traffic Control (ATC) system and Unmanned Aerial Vehicle (UAV) navigation system applications. Secondly, in an attempt to study the CPSs' vulnerabilities in more detail, we further discuss a methodology to identify potential cyber threats inherent in the given CPSs and quantify the attack severity accordingly. We then develop an analytical algorithm to test the behavior of the CPS under various cyber attack combinations. Compared to a numerical approach, the analytical algorithm enables the prediction of the most effective cyber attack combinations without computing the severity of all possible attack combinations, thereby greatly reducing the

  15. Does leisure-time physical activity attenuate or eliminate the positive association between obesity and high blood pressure?

    Science.gov (United States)

    Werneck, André O; Oyeyemi, Adewale L; Gerage, Aline M; Cyrino, Edilson S; Szwarcwald, Célia L; Sardinha, Luís B; Silva, Danilo R

    2018-04-25

    We examine the joint association of weight status and leisure-time physical activity on high blood pressure in a nationally representative sample of adults and older adults in Brazil. This was a national cross-sectional survey conducted in Brazil in 2013 (Brazilian Health Survey). The sample consisted of 59 402 participants (56% women, aged 18 to 100 years). Outcome was objectively assessed blood pressure. Body mass index (BMI) was objectively measured, while self-reported information on leisure-time physical activity, TV viewing, chronological age, race, educational status, tobacco smoking, sodium consumption, and hypertension medication was obtained using questionnaires. Logistic regression analysis with adjusted odds ratio was conducted to test the joint association of BMI and leisure-time physical activity categories on high blood pressure. Overall, compared to normal weight (NW) and physically active group, the NW/inactive (OR = 1.28; 1.04 to 1.58), overweight/active (OR = 1.38; 1.08 to 1.78), overweight/inactive (OR = 1.89; 1.53 to 2.33), obese/active (OR = 2.19; 1.59 to 3.01) and obese/inactive (OR = 2.54; 2.05 to 3.15) groups were 28% to 254% more likely to have high blood pressure. The attenuation and high blood pressure was greater for women and adults than for men and older adults. Thus, leisure-time physical inactivity and being overweight and obesity were associated with high blood pressure in Brazilian population. Engaging in sufficient level of physical activity during leisure could attenuate, but not eliminate, the negative influence of obesity on high blood pressure in Brazilian adults and older adults. ©2018 Wiley Periodicals, Inc.

  16. Physical exercise improves functional recovery through mitigation of autophagy, attenuation of apoptosis and enhancement of neurogenesis after MCAO in rats.

    Science.gov (United States)

    Zhang, Liying; Hu, Xiquan; Luo, Jing; Li, Lili; Chen, Xingyong; Huang, Ruxun; Pei, Zhong

    2013-04-08

    Physical exercise improves functional recovery after stroke through a complex mechanism that is not fully understood. Transient focal cerebral ischemia induces autophagy, apoptosis and neurogenesis in the peri-infarct region. This study is aimed to examine the effects of physical exercise on autophagy, apoptosis and neurogenesis in the peri-infarct region in a rat model of transient middle cerebral artery occlusion (MCAO). We found that autophagosomes, as labeled by microtubule-associated protein 1A light chain 3-II (LC3-II), were evident in the peri-infarct region at 3 days after 90-minute MCAO. Moreover, 44.6% of LC3-positive cells were also stained with TUNEL. The number of LC3 positive cells was significantly lower in physical exercise group than in control group at 14 and 21 days after MCAO. Suppression of autophagosomes by physical exercise was positively associated with improvement of neurological function. In addition, physical exercise significantly decreased the number of TUNEL-positive cells and increased the numbers of Ki67-positive, a proliferative marker, and insulin-like growth factor-1 (IGF-1) positive cells at 7, 14, and 21 days after MCAO. The present results demonstrate that physical exercise enhances neurological function possibly by reduction of autophagosome accumulation, attenuation of apoptosis and enhancement of neurogenesis in the peri-infarct region after transient MCAO in rats.

  17. Attenuation of Morphine Physical Dependence and Blood Levels of Cortisol by Central and Systemic Administration of Ramelteon in Rat

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    Majid Motaghinejad

    2015-05-01

    Full Text Available Background: Chronic administration of morphine cause physical dependence but the exact mechanism of this phenomenon remains unclear. The aim of this study is the assessment of systemic and intracerebroventricular (icv administration of ramelteon (a melatonin receptor agonist on morphine physical dependence. Methods: 88 adult male rats were divided into 2 major groups, namely “systematic” and “central” administration of ramelteon. In the first category, systemic administration of ramelteon at various dosages (10, 20, and 40 mg/kg was assessed on dependent animals and withdrawal signs were compared with positive (received morphine and saline as systemic administration, negative control (saline and group under treatment by ramelteon (40 mg/kg groups. In the second category, central administration of ramelteon at various dosages (25, 50, or 100 μg, was assessed on dependent animals and withdrawal signs were compared with the positive control (received morphine and saline as icv and negative control (saline groups, and the group under treatment by ramelteon (50 μg/5 μl/rat. On the test day, all animals received naloxone (3 mg/kg and were observed for withdrawal signs. Total withdrawal score (TWS was also determined. Finally, to evaluate the stress level of dependent rats, blood cortisols were measured. Results: Central administration of ramelteon in all doses and systemic administration in high doses attenuate withdrawal syndrome in comparison with the dependent positive control group (P<0.05. Both central and systemic administrations of ramelteon can attenuate the blood cortisol level in comparison with the dependent positive control group (P<0.05. Conclusion: In conclusion, we found that central administration of ramelteon attenuated morphine withdrawal symptoms and cortisol level as a stress marker.

  18. Using physical approaches for the attenuation of lactic acid bacteria in an organic rice beverage.

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    Bevilacqua, Antonio; Casanova, Francesco Pio; Petruzzi, Leonardo; Sinigaglia, Milena; Corbo, Maria Rosaria

    2016-02-01

    A wild strain of Lactobacillus plantarum, isolated from an Italian sourdough, was inoculated in an organic rice drink; however, it caused a strong acidification. Thus, it was preliminary processed through homogenization (single or multiple passes) or sonication (US) and then inoculated in the beverage. The samples were stored at 4 °C and analyzed to assess pH, production of lactic acid, viable count and sensory scores. A US-2-step process (power, 80%) could control acidification; viability and sensory traits were never affected by sonication. This result was confirmed on two commercial probiotics (Lactobacillus casei LC01 and Bifidobacterium animalis subsp. lactis Bb12). In the 2nd step samples inoculated with attenuated strains were also stored under thermal abuse conditions (25 or 37 °C for 4 or 24 h, then at 4 °C) and the results showed that US could control acidification for a short thermal abuse. Finally, US-attenuated starter cultures were inoculated in the rice drink containing β-glucans as healthy compounds; the targets did not cause any significant change of prebiotic. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Low Intensity Physical Exercise Attenuates Cardiac Remodeling and Myocardial Oxidative Stress and Dysfunction in Diabetic Rats

    Directory of Open Access Journals (Sweden)

    C. Gimenes

    2015-01-01

    Full Text Available We evaluated the effects of a low intensity aerobic exercise protocol on cardiac remodeling and myocardial function in diabetic rats. Wistar rats were assigned into four groups: sedentary control (C-Sed, exercised control (C-Ex, sedentary diabetes (DM-Sed, and exercised diabetes (DM-Ex. Diabetes was induced by intraperitoneal injection of streptozotocin. Rats exercised for 9 weeks in treadmill at 11 m/min, 18 min/day. Myocardial function was evaluated in left ventricular (LV papillary muscles and oxidative stress in LV tissue. Statistical analysis was given by ANOVA or Kruskal-Wallis. Echocardiogram showed diabetic groups with higher LV diastolic diameter-to-body weight ratio and lower posterior wall shortening velocity than controls. Left atrium diameter was lower in DM-Ex than DM-Sed (C-Sed: 5.73±0.49; C-Ex: 5.67±0.53; DM-Sed: 6.41±0.54; DM-Ex: 5.81±0.50 mm; P<0.05 DM-Sed vs C-Sed and DM-Ex. Papillary muscle function was depressed in DM-Sed compared to C-Sed. Exercise attenuated this change in DM-Ex. Lipid hydroperoxide concentration was higher in DM-Sed than C-Sed and DM-Ex. Catalase and superoxide dismutase activities were lower in diabetics than controls and higher in DM-Ex than DM-Sed. Glutathione peroxidase activity was lower in DM-Sed than C-Sed and DM-Ex. Conclusion. Low intensity exercise attenuates left atrium dilation and myocardial oxidative stress and dysfunction in type 1 diabetic rats.

  20. Physical modeling and analysis of P-wave attenuation anisotropy in transversely isotropic media

    Digital Repository Service at National Institute of Oceanography (India)

    Zhu, Y.; Tsvankin, I.; Dewangan, P.; Van Wijk, K.

    here H20849Figures 1 and 2aH20850 was to verify the accuracy of the parameter-esti- mation results obtained by Dewangan et al. H208492006H20850. The P-wave source H20849a flat-faced, cylindrical, piezoelectric-contact transducerH20850 was fixed... are assumed to be constant. Receivers 10.8 cm 60 cm Source 70? symmetry axis Figure 1. Physical model of a TI layer with the symmetry axis tilted at 70? H20849from Dewangan et al., 2006H20850. The transmitted wavefield is excited by an ultrasonic contact...

  1. Regular physical activity attenuates the blood pressure response to public speaking and delays the development of hypertension.

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    Palatini, Paolo; Bratti, Paolo; Palomba, Daniela; Saladini, Francesca; Zanatta, Nello; Maraglino, Giuseppe

    2010-06-01

    The objective of this study was to investigate the effect of regular physical activity on the haemodynamic response to public speaking and to evaluate the long-term effect of exercise on development of hypertension. We assessed 75 sedentary and 44 active participants screened for stage 1 hypertension with consistent activity habits and 63 normotensive individuals as control. The blood pressure (BP) response to public speaking was assessed with beat-to-beat noninvasive recording. Definition of incident hypertension was based either on clinic or 24-h BP measurement. The BP response to public speaking was greater in the hypertensive than the normotensive participants (P=0.018/0.009). Among the former, sedentary participants showed increased BP reactivity to the speech test (45.2+/-22.6/22.2+/-11.5mmHg, Ppublic speaking into the Cox model influenced the strength of the association only marginally [hazard ratio=0.55 (95% CI 0.30-0.97) and hazard ratio=0.59 (95% CI 0.36-0.99), respectively]. Regular physical activity attenuates the BP reaction to psychosocial stressors. However, this mechanism seems to be only partially responsible for the long-term effect of exercise on BP.

  2. Physical activity does not attenuate the relationship between daily cortisol and metabolic syndrome in obese youth.

    Science.gov (United States)

    Guseman, Emily Hill; Pfeiffer, Karin A; Carlson, Joseph J; Stansbury, Kathy; Eisenmann, Joey C

    2016-01-01

    We examined the associations among daily cortisol, physical activity (MVPA) and continuous metabolic syndrome score (cMetS) in obese youth. Fifty adolescents (mean age 14.8 ± 1.9 years) were recruited from medical clinics. Daily MVPA (min/day) was assessed by accelerometry. Saliva was sampled at prescribed times: immediately upon waking; 30 min after waking; and 3, 6 and 9 h after waking. Fasting lipids, glucose, waist circumference and blood pressure were used to calculate a continuous metabolic syndrome score (cMetS). Multiple linear regression analysis was used to examine associations among variables. The mean cMetS score was 4.16 ± 4.30 and did not differ by clinic or sex. No significant relationship was found between cortisol area under the curve (cAUC) and cMetS, nor did the interaction of MVPA with cAUC significantly predict cMetS. Physical activity, cortisol, and metabolic risk were not associated in this sample of obese adolescents. Future research should examine the role of insulin sensitivity in these relationships.

  3. Attenuating the mortality risk of high serum uric acid: the role of physical activity underused.

    Science.gov (United States)

    Chen, Jiunn-Horng; Wen, Chi Pang; Wu, Shiuan Bei; Lan, Joung-Liang; Tsai, Min Kuang; Tai, Ya-Ping; Lee, June Han; Hsu, Chih Cheng; Tsao, Chwen Keng; Wai, Jackson Pui Man; Chiang, Po Huang; Pan, Wen Han; Hsiung, Chao Agnes

    2015-11-01

    High serum uric acid (sUA) has been associated with increased mortality risks, but its clinical treatment varied with potential side effects. The role of physical activity has received limited attention. A cohort, consisting of 467 976 adults, who went through a standard health screening programme, with questionnaire and fasting blood samples, was successively recruited between 1996 and 2008. High sUA is defined as uric acid above 7.0 mg/dL. Leisure time physical activity level was self-reported, with fully active defined as those with 30 min per day for at least 5 days a week. National death file identified 12 228 deaths with a median follow-up of 8.5 years. Cox proportional model was used to analyse HRs, and 12 variables were controlled, including medical history, life style and risk factors. High sUA constituted one quarter of the cohort (25.6%). Their all-cause mortality was significantly increased [HR: 1.22 (1.15-1.29)], with much of the increase contributed to by the inactive (HR: 1.27 (1.17-1.37)), relative to the reference group with sUA level of 5-6 mg/dL. When they were fully active, mortality risks did not increase, but decreased by 11% (HR: 0.89 (0.82-0.97)), reflecting the benefits of being active was able to overcome the adverse effects of high sUA. Given the same high sUA, a 4-6 years difference in life expectancy was found between the active and the inactive. Physical activity is a valuable alternative to pharmacotherapy in its ability to reduce the increases in mortality risks from high sUA. By being fully active, exercise can extend life span by 4-6 years, a level greater than the 1-4 years of life-shortening effect from high sUA. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  4. Physical activity attenuates the influence of FTO variants on obesity risk: a meta-analysis of 218,166 adults and 19,268 children.

    Directory of Open Access Journals (Sweden)

    Tuomas O Kilpeläinen

    2011-11-01

    Full Text Available The FTO gene harbors the strongest known susceptibility locus for obesity. While many individual studies have suggested that physical activity (PA may attenuate the effect of FTO on obesity risk, other studies have not been able to confirm this interaction. To confirm or refute unambiguously whether PA attenuates the association of FTO with obesity risk, we meta-analyzed data from 45 studies of adults (n = 218,166 and nine studies of children and adolescents (n = 19,268.All studies identified to have data on the FTO rs9939609 variant (or any proxy [r(2>0.8] and PA were invited to participate, regardless of ethnicity or age of the participants. PA was standardized by categorizing it into a dichotomous variable (physically inactive versus active in each study. Overall, 25% of adults and 13% of children were categorized as inactive. Interaction analyses were performed within each study by including the FTO×PA interaction term in an additive model, adjusting for age and sex. Subsequently, random effects meta-analysis was used to pool the interaction terms. In adults, the minor (A- allele of rs9939609 increased the odds of obesity by 1.23-fold/allele (95% CI 1.20-1.26, but PA attenuated this effect (p(interaction  = 0.001. More specifically, the minor allele of rs9939609 increased the odds of obesity less in the physically active group (odds ratio  = 1.22/allele, 95% CI 1.19-1.25 than in the inactive group (odds ratio  = 1.30/allele, 95% CI 1.24-1.36. No such interaction was found in children and adolescents.The association of the FTO risk allele with the odds of obesity is attenuated by 27% in physically active adults, highlighting the importance of PA in particular in those genetically predisposed to obesity.

  5. Seismic attenuation and scattering tomography of rock samples using stochastic wavefields: linking seismology, volcanology, and rock physics.

    Science.gov (United States)

    Fazio, Marco; De Siena, Luca; Benson, Phillip

    2016-04-01

    Seismic attenuation and scattering are two attributes that can be linked with porosity and permeability in laboratory experiments. When measuring these two quantities using seismic waveforms recorder at lithospheric and volcanic scales the areas of highest heterogeneity, as batches of melt and zones of high deformation, produce anomalous values of the measured quantities, the seismic quality factor and scattering coefficient. When employed as indicators of heterogeneity and absorption in volcanic areas these anomalous effects become strong indicators of magma accumulation and tectonic boundaries, shaping magmatic chambers and conduit systems. We perform attenuation and scattering measurements and imaging using seismic waveforms produced in laboratory experiments, at frequencies ranging between the kHz and MHz. As attenuation and scattering are measured from the shape of the envelopes, disregarding phases, we are able to connect the observations with the micro fracturing and petrological quantities previously measured on the sample. Connecting the imaging of dry and saturated samples via these novel attributes with the burst of low-period events with increasing saturation and deformation is a challenge. Its solution could plant the seed for better relating attenuation and scattering tomography measurements to the presence of fluids and gas, therefore creating a novel path for reliable porosity and permeability tomography. In particular for volcanoes, being able to relate attenuation/scattering measurements with low-period micro seismicity could deliver new data to settle the debate about if both source and medium can produce seismic resonance.

  6. Physical exercise prevents short and long-term deficits on aversive and recognition memory and attenuates brain oxidative damage induced by maternal deprivation.

    Science.gov (United States)

    Neves, Ben-Hur; Menezes, Jefferson; Souza, Mauren Assis; Mello-Carpes, Pâmela B

    2015-12-01

    It is known from previous research that physical exercise prevents long-term memory deficits induced by maternal deprivation in rats. But we could not assume similar effects of physical exercise on short-term memory, as short- and long-term memories are known to result from some different memory consolidation processes. Here we demonstrated that, in addition to long-term memory deficit, the short-term memory deficit resultant from maternal deprivation in object recognition and aversive memory tasks is also prevented by physical exercise. Additionally, one of the mechanisms by which the physical exercise influences the memory processes involves its effects attenuating the oxidative damage in the maternal deprived rats' hippocampus and prefrontal cortex.

  7. α-Terpineol attenuates morphine-induced physical dependence and tolerance in mice: role of nitric oxide.

    Science.gov (United States)

    Parvardeh, Siavash; Moghimi, Mahsa; Eslami, Pegah; Masoudi, Alireza

    2016-02-01

    Dependence and tolerance to opioid analgesics are major problems limiting their clinical application. α-Terpineol is a monoterpenoid alcohol with neuroprotective effects which is found in several medicinal plants such as Myrtus communis, Laurus nobilis, and Stachys byzantina. It has been shown that some of these medicinal plants such as S. byzantina attenuate dependence and tolerance to morphine. Since α-terpineol is one of the bioactive phytochemical constituent of these medicinal plants, the present study was conducted to investigate the effects of α-terpineol on morphine-induced dependence and tolerance in mice. The mice were rendered dependent or tolerant to morphine by a 3-day administration schedule. The hot-plate test and naloxone-induced withdrawal syndrome were used to evaluate tolerance and dependence on morphine, respectively. To investigate a possible role for nitric oxide (NO) in the protective effect of α-terpineol, the NO synthase inhibitor, L-N(G)-nitroarginine methyl ester (L-NAME) and NO precursor, L-arginine, were used. Administration of α-terpineol (5, 10, and 20 mg/kg, IP) significantly decreased the number of jumps in morphine dependent animals. Moreover, α-terpineol (20 and 40 mg/kg, IP) attenuated tolerance to the analgesic effect of morphine. The inhibitory effects of α-terpineol on morphine-induced dependence and tolerance were enhanced by pretreatment with L-NAME (10 mg/kg, IP). However, L-arginine (300 mg/kg, IP) antagonized the protective effects of α-terpineol on dependence and tolerance to morphine. These findings indicate that α-terpineol prevents the development of dependence and tolerance to morphine probably through the influence on NO production.

  8. Leisure-Time Physical Activity Does not Attenuate the Association Between Occupational Sedentary Behavior and Obesity: Results From Alberta's Tomorrow Project.

    Science.gov (United States)

    Nicholas, Joshua A; Lo Siou, Geraldine; Lynch, Brigid M; Robson, Paula J; Friedenreich, Christine M; Csizmadi, Ilona

    2015-12-01

    Sedentary behavior has been proposed as a risk factor for obesity that is distinct from physical inactivity. This study aimed to examine the association between occupational sedentary behavior and obesity, and to determine if this association is independent of leisure-time physical activity (LTPA). Fully employed participants enrolled between 2001 and 2008 to Alberta's Tomorrow Project, a prospective cohort study in Alberta, Canada, were studied (n = 12,409). Associations between occupational sedentary behavior and waist circumference (WC), waist-to-hip ratio (WHR), and body mass index (BMI) were examined using multiple binary and multinomial logistic regressions. In men, a positive association was observed between daily occupational sedentary hours and WC, WHR, BMI, and with high risk profiles that incorporated both BMI and WC (P < .01). Controlling for vigorous-intensity LTPA in all models strengthened associations between sedentary behavior and measures of obesity. In contrast, inverse associations were observed for occupational sedentary hours and WHR for women (P < .05). In fully employed men, occupational sedentary behavior was positively associated with obesity risk that was not attenuated by physical activity. In women, an increase in obesity risk was not observed with sedentary behavior. Gender differences in the health effects of sedentary behavior require further study.

  9. Modulation of Cervical Facet Joint Nociception and Pain Attenuates Physical and Psychological Features of Chronic Whiplash: A Prospective Study.

    Science.gov (United States)

    Smith, Ashley Dean; Jull, Gwendolen; Schneider, Geoff M; Frizzell, Bevan; Hooper, Robert A; Sterling, Michele

    2015-09-01

    To investigate changes in clinical (physical and psychological) features of individuals with chronic whiplash-associated disorder who had previously undergone cervical radiofrequency neurotomy at the time point when the effects of radiofrequency neurotomy had dissipated and pain returned. Prospective cohort observational trial of consecutive patients. Tertiary spinal intervention centre in Calgary, Alberta, Canada. A total of 53 consecutive individuals with chronic whiplash-associated disorder. Individuals underwent radiofrequency neurotomy and were assessed before radiofrequency neurotomy, at 1 and 3 months postprocedure, and then after the return of pain (approximately 10 months postprocedure). Quantitative sensory tests (pressure; thermal pain thresholds; brachial plexus provocation test), nociceptive flexion reflex, and motor function (cervical range of movement; craniocervical flexion test) were measured. Self-reported disability, psychological distress, pain catastrophization, and posttraumatic stress disorder symptoms also were measured. Upon the return of pain after radiofrequency neurotomy, levels of disability increased (P .22). There were no significant changes in pressure hyperalgesia (P > .054) or craniocervical flexion test performance (P > .07) after the return of pain. Psychological distress and pain catastrophizing increased significantly after the return of pain (P .13). However, there was no difference in number or severity of posttraumatic stress symptoms after the return of pain (P > .30). Physical and psychological features of chronic whiplash-associated disorder are modulated dynamically with cervical radiofrequency neurotomy. These findings indicate that peripheral nociception is involved in the manifestations of chronic whiplash-associated disorder in this cohort of individuals. Copyright © 2015 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

  10. Treadmill exercise attenuates the severity of physical dependence, anxiety, depressive-like behavior and voluntary morphine consumption in morphine withdrawn rats receiving methadone maintenance treatment.

    Science.gov (United States)

    Alizadeh, Maryam; Zahedi-Khorasani, Mahdi; Miladi-Gorji, Hossein

    2018-05-30

    This study was designed to examine whether treadmill exercise would attenuate the severity of physical dependence, methadone-induced anxiety, depression and voluntary morphine consumption in morphine withdrawn rats receiving methadone maintenance treatment (MMT). The rats were chronically treated with bi-daily doses (10 mg/kg, at 12 h intervals) of morphine for 14 days. The exercising rats receiving MMT were forced to run on a motorized treadmill for 30 days during morphine withdrawal. Then, rats were tested for the severity of morphine dependence, the elevated plus-maze (EPM), sucrose preference test (SPT) and voluntary morphine consumption using a two-bottle choice (TBC) paradigm. The results showed that naloxone- precipitated opioid withdrawal signs were decreased in exercising morphine-dependent rats receiving MMT than sedentary rats. Also, the exercising morphine-dependent rats receiving MMT exhibited an increased time on open arms, preference for sucrose and a lower morphine preference ratio than sedentary rats. We conclude that treadmill exercise decreased the severity of physical dependence, anxiety/depressive-like behaviors and also the voluntary morphine consumption in morphine withdrawn rats receiving MMT. Thus, exercise may benefit in the treatment of addicts during MMT. Copyright © 2018. Published by Elsevier B.V.

  11. Associations of discretionary screen time with mortality, cardiovascular disease and cancer are attenuated by strength, fitness and physical activity: findings from the UK Biobank study.

    Science.gov (United States)

    Celis-Morales, Carlos A; Lyall, Donald M; Steell, Lewis; Gray, Stuart R; Iliodromiti, Stamatina; Anderson, Jana; Mackay, Daniel F; Welsh, Paul; Yates, Thomas; Pell, Jill P; Sattar, Naveed; Gill, Jason M R

    2018-05-24

    markedly attenuated in those with the highest levels of grip strength, fitness and physical activity. Thus, if these associations are causal, the greatest benefits from health promotion interventions to reduce discretionary screen time may be seen in those with low levels of strength, fitness and physical activity.

  12. Rutin, a flavonoid and principal component of saussurea involucrata, attenuates physical fatigue in a forced swimming mouse model.

    Science.gov (United States)

    Su, Kang-Yi; Yu, Chao Yuan; Chen, Yue-Wen; Huang, Yi-Tsau; Chen, Chun-Ting; Wu, Hsueh-Fu; Chen, Yi-Lin Sophia

    2014-01-01

    This study investigated the antifatigue effects of rutin, a flavonoid extracted from the ethyl acetate extract of S. involucrata. Mice were subjected to a weight-loaded forced swim test (WFST) on alternate days for 3 wk. Rutin was administered orally to the mice for 7 days in dosages of 15, 30, and 60 mg/kg body weight, and several biomarkers of physical fatigue were evaluated: swimming time, change in body weight, lipid peroxidation, lactic acid (LA), glycogen, and the activities of the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx). On Day 7, the rutin-treated mice had a 3-fold longer exhaustive swimming time than the control mice, as well as significantly reduced blood LA concentrations. The 15, 30, and 60 mg/kg body weight rutin-supplemented groups displayed 11.2%, 22.5%, and 37.7% reduced malondialdehyde (MDA) concentrations, respectively, in brain and muscle tissues compared with the control exercised group. Our results indicated that the administration of rutin protected the mice against the depletion of SOD and GPx activities significantly. Following 7 days of rutin treatment, we sacrificed the mice and analyzed their soleus muscle and brain for peroxisome proliferator-activated receptor-α coactivator (PGC-1α) and sirtuin 1 (SIRT1) mRNA expression. We observed that rutin treatment increased PGC-1α and SIRT1 mRNA and protein expression. The changes in these markers of mitochondrial biogenesis were associated with increased maximal endurance capacity. The application of 2D gel electrophoresis to analyze the rutin-responsive protein profiles in the WFST mouse brain further revealed the upregulation of the CB1 cannabinoid receptor-interacting protein 1, myelin basic protein, Rho GDP dissociation inhibitor (GDI) alpha, and TPI, indicating that rutin might inhibit anxiety through the upregulation of the expression of anxiety-associated proteins. Western blot analysis of MAPK expression further confirmed the antianxiety effects

  13. Application of Terahertz Attenuated Total Reflection Spectroscopy to Detect Changes in the Physical Properties of Lactose during the Lubrication Process Required for Drug Formulation.

    Science.gov (United States)

    Dohi, Masafumi; Momose, Wataru; Yamashita, Kazunari; Hakomori, Tadashi; Sato, Shusaku; Noguchi, Shuji; Terada, Katsuhide

    2017-02-01

    Manufacturing the solid dosage form of an orally administered drug requires lubrication to enhance manufacturability, ensuring that critical quality attributes such as disintegration and dissolution of the drug product are maintained during manufacture. Here, to evaluate lubrication performance during manufacture, we used terahertz attenuated total reflection (THz-ATR) spectroscopy to detect differences in the physical characteristics of the lubricated powder. We applied a simple formulation prepared by blending granulated lactose as filler with magnesium stearate as lubricant. A flat tablet was prepared using the lubricated powder to acquire sharp THz-ATR absorption peaks of the samples. First, we investigated the effects of lubricant concentration and compression pressure on preparation of the tablet and then determined the effect of the pressure applied to samples in contact with the ATR prism on sample absorption amplitude. We focused on the differences in the magnitudes of spectra at the lactose-specific frequency. Second, we conducted the dynamic lubrication process using a 120-L mixer to investigate differences in the magnitudes of absorption corresponding to the lactose-specific frequency during lubrication. In both studies, enriching the lubricated powder with a higher concentration of magnesium stearate or prolonging blending time correlated with higher magnitudes of spectra at the lactose-specific frequency. Further, in the dynamic lubrication study, the wettability and disintegration time of the tablets were compared with the absorption spectra amplitudes at the lactose-specific frequency. We conclude that THz-ATR spectroscopy is useful for detecting differences in densities caused by a change in the physical properties of lactose during lubrication.

  14. Physical activity attenuates the genetic predisposition to obesity in 20,000 men and women from EPIC-Norfolk prospective population study.

    Directory of Open Access Journals (Sweden)

    Shengxu Li

    2010-08-01

    Full Text Available We have previously shown that multiple genetic loci identified by genome-wide association studies (GWAS increase the susceptibility to obesity in a cumulative manner. It is, however, not known whether and to what extent this genetic susceptibility may be attenuated by a physically active lifestyle. We aimed to assess the influence of a physically active lifestyle on the genetic predisposition to obesity in a large population-based study.We genotyped 12 SNPs in obesity-susceptibility loci in a population-based sample of 20,430 individuals (aged 39-79 y from the European Prospective Investigation of Cancer (EPIC-Norfolk cohort with an average follow-up period of 3.6 y. A genetic predisposition score was calculated for each individual by adding the body mass index (BMI-increasing alleles across the 12 SNPs. Physical activity was assessed using a self-administered questionnaire. Linear and logistic regression models were used to examine main effects of the genetic predisposition score and its interaction with physical activity on BMI/obesity risk and BMI change over time, assuming an additive effect for each additional BMI-increasing allele carried. Each additional BMI-increasing allele was associated with 0.154 (standard error [SE] 0.012 kg/m(2 (p = 6.73 x 10(-37 increase in BMI (equivalent to 445 g in body weight for a person 1.70 m tall. This association was significantly (p(interaction = 0.005 more pronounced in inactive people (0.205 [SE 0.024] kg/m(2 [p = 3.62 x 10(-18; 592 g in weight] than in active people (0.131 [SE 0.014] kg/m(2 [p = 7.97 x 10(-21; 379 g in weight]. Similarly, each additional BMI-increasing allele increased the risk of obesity 1.116-fold (95% confidence interval [CI] 1.093-1.139, p = 3.37 x 10(-26 in the whole population, but significantly (p(interaction = 0.015 more in inactive individuals (odds ratio [OR] = 1.158 [95% CI 1.118-1.199; p = 1.93 x 10(-16] than in active individuals (OR = 1.095 (95% CI 1.068-1.123; p = 1

  15. Physical activity attenuates the mid-adolescent peak in insulin resistance but by late adolescence the effect is lost: a longitudinal study with annual measures from 9-16 years (EarlyBird 66).

    Science.gov (United States)

    Metcalf, Brad S; Hosking, Joanne; Henley, William E; Jeffery, Alison N; Mostazir, Mohammod; Voss, Linda D; Wilkin, Terence J

    2015-12-01

    The aim of this work was to test whether the mid-adolescent peak in insulin resistance (IR) and trends in other metabolic markers are influenced by long-term exposure to physical activity. Physical activity (7 day ActiGraph accelerometry), HOMA-IR and other metabolic markers (glucose, fasting insulin, HbA1c, lipids and BP) were measured annually from age 9 years to 16 years in 300 children (151 boys) from the EarlyBird study in Plymouth, UK. The activity level of each child was characterised, with 95% reliability, by averaging their eight annual physical activity measures. Age-related trends in IR and metabolic health were analysed by multi-level modelling, with physical activity as the exposure measure (categorical and continuous) and body fat percentage (assessed by dual-energy X-ray absorptiometry) and pubertal status (according to age at peak height velocity and Tanner stage) as covariates. The peak in IR at age 12-13 years was 17% lower (p adolescents independently of body fat percentage and pubertal status. However, this difference diminished progressively over the next 3 years and had disappeared completely by the age of 16 years (e.g. difference was -14% at 14 years, -8% at 15 years and +1% at 16 years; 'physical activity × age(2), interaction, p adolescence in the more active group. Our finding that physical activity attenuates IR during mid-adolescence may be clinically important. It remains to be established whether the temporary attenuation in IR during this period has implications for the development of diabetes in adolescence and for future metabolic health generally.

  16. Dexmedetomidine in premedication to attenuate the acute ...

    African Journals Online (AJOL)

    Background: The choice of anaesthetic agent for electroconvulsive therapy (ECT) depends on seizure duration, haemodynamic ... and infarction. To attenuate this acute ... scheduled for ECT, physical status ASA I and II, age between 18 and.

  17. Tracer attenuation in groundwater

    Science.gov (United States)

    Cvetkovic, Vladimir

    2011-12-01

    The self-purifying capacity of aquifers strongly depends on the attenuation of waterborne contaminants, i.e., irreversible loss of contaminant mass on a given scale as a result of coupled transport and transformation processes. A general formulation of tracer attenuation in groundwater is presented. Basic sensitivities of attenuation to macrodispersion and retention are illustrated for a few typical retention mechanisms. Tracer recovery is suggested as an experimental proxy for attenuation. Unique experimental data of tracer recovery in crystalline rock compare favorably with the theoretical model that is based on diffusion-controlled retention. Non-Fickian hydrodynamic transport has potentially a large impact on field-scale attenuation of dissolved contaminants.

  18. The LCLS Gas Attenuator Revisited

    International Nuclear Information System (INIS)

    Ryutov, D

    2005-01-01

    In the report ''X-ray attenuation cell'' [1] a preliminary analysis of the gas attenuator for the Linac Coherent Light Source (LCLS) was presented. This analysis was carried out for extremely stringent set of specifications. In particular, a very large diameter for the unobstructed beam was set (1 cm) to accommodate the spontaneous radiation; the attenuator was supposed to cover the whole range of energies of the coherent radiation, from 800 eV to 8000 eV; the maximum attenuation was set at the level of 10 4 ; the use of solid attenuators was not allowed, as well as the use of rotating shutters. The need to reach a sufficient absorption at the high-energy end of the spectrum predetermined the choice of Xe as the working gas (in order to have a reasonable absorption at a not-too-high pressure). A sophisticated differential pumping system that included a Penning-type ion pump was suggested in order to minimize the gas leak into the undulator/accelerator part of the facility. A high cost of xenon meant also that an efficient (and expensive) gas-recovery system would have to be installed. The main parameter that determined the high cost and the complexity of the system was a large radius of the orifice. The present viewpoint allows for much smaller size of the orifice, r 0 = 1.5 mm. (1) The use of solid attenuators is also allowed (R.M. Bionta, private communication). It is, therefore, worthwhile to reconsider various parameters of the gas attenuator for these much less stringent conditions. This brief study should be considered as a physics input for the engineering design. As a working gas we consider now the argon, which, on the one hand, provides a reasonable absorption lengths and, on the other hand, is inexpensive enough to be exhausted into the atmosphere (no recovery). The absorption properties of argon are illustrated by Fig.1 where the attenuation factor A is shown for various beam energies, based on Ref. [2]. The other relevant parameters for argon are

  19. Ultrasonic attenuation in rare-earth monoarsenides

    Indian Academy of Sciences (India)

    2015-11-27

    Home; Journals; Pramana – Journal of Physics; Volume 86; Issue 6. Ultrasonic attenuation in rare-earth monoarsenides .... Proceedings of the International Workshop/Conference on Computational Condensed Matter Physics and Materials Science (IWCCMP-2015). Posted on November 27, 2015. Guest Editors: Anurag ...

  20. Does physical activity attenuate, or even eliminate, the detrimental association of sitting time with mortality? A harmonised meta-analysis of data from more than 1 million men and women.

    Science.gov (United States)

    Ekelund, Ulf; Steene-Johannessen, Jostein; Brown, Wendy J; Fagerland, Morten Wang; Owen, Neville; Powell, Kenneth E; Bauman, Adrian; Lee, I-Min

    2016-09-24

    High amounts of sedentary behaviour have been associated with increased risks of several chronic conditions and mortality. However, it is unclear whether physical activity attenuates or even eliminates the detrimental effects of prolonged sitting. We examined the associations of sedentary behaviour and physical activity with all-cause mortality. We did a systematic review, searching six databases (PubMed, PsycINFO, Embase, Web of Science, Sport Discus, and Scopus) from database inception until October, 2015, for prospective cohort studies that had individual level exposure and outcome data, provided data on both daily sitting or TV-viewing time and physical activity, and reported effect estimates for all-cause mortality, cardiovascular disease mortality, or breast, colon, and colorectal cancer mortality. We included data from 16 studies, of which 14 were identified through a systematic review and two were additional unpublished studies where pertinent data were available. All study data were analysed according to a harmonised protocol, which categorised reported daily sitting time and TV-viewing time into four standardised groups each, and physical activity into quartiles (in metabolic equivalent of task [MET]-hours per week). We then combined data across all studies to analyse the association of daily sitting time and physical activity with all-cause mortality, and estimated summary hazard ratios using Cox regression. We repeated these analyses using TV-viewing time instead of daily sitting time. Of the 16 studies included in the meta-analysis, 13 studies provided data on sitting time and all-cause mortality. These studies included 1 005 791 individuals who were followed up for 2-18·1 years, during which 84 609 (8·4%) died. Compared with the referent group (ie, those sitting 35·5 MET-h per week]), mortality rates during follow-up were 12-59% higher in the two lowest quartiles of physical activity (from HR=1·12, 95% CI 1·08-1·16, for the second lowest

  1. PHYSICS

    CERN Multimedia

    P. Sphicas

    There have been three physics meetings since the last CMS week: “physics days” on March 27-29, the Physics/ Trigger week on April 23-27 and the most recent physics days on May 22-24. The main purpose of the March physics days was to finalize the list of “2007 analyses”, i.e. the few topics that the physics groups will concentrate on for the rest of this calendar year. The idea is to carry out a full physics exercise, with CMSSW, for select physics channels which test key features of the physics objects, or represent potential “day 1” physics topics that need to be addressed in advance. The list of these analyses was indeed completed and presented in the plenary meetings. As always, a significant amount of time was also spent in reviewing the status of the physics objects (reconstruction) as well as their usage in the High-Level Trigger (HLT). The major event of the past three months was the first “Physics/Trigger week” in Apri...

  2. SEISMIC ATTENUATION FOR RESERVOIR CHARACTERIZATION

    Energy Technology Data Exchange (ETDEWEB)

    Joel Walls; M.T. Taner; Gary Mavko; Jack Dvorkin

    2002-01-01

    In Section 1 of this first report we will describe the work we are doing to collect and analyze rock physics data for the purpose of modeling seismic attenuation from other measurable quantities such as porosity, water saturation, clay content and net stress. This work and other empirical methods to be presented later, will form the basis for ''Q pseudo-well modeling'' that is a key part of this project. In Section 2 of this report, we will show the fundamentals of a new method to extract Q, dispersion, and attenuation from field seismic data. The method is called Gabor-Morlet time-frequency decomposition. This technique has a number of advantages including greater stability and better time resolution than spectral ratio methods.

  3. Macroseismic intensity attenuation in Iran

    Science.gov (United States)

    Yaghmaei-Sabegh, Saman

    2018-01-01

    Macroseismic intensity data plays an important role in the process of seismic hazard analysis as well in developing of reliable earthquake loss models. This paper presents a physical-based model to predict macroseismic intensity attenuation based on 560 intensity data obtained in Iran in the time period 1975-2013. The geometric spreading and energy absorption of seismic waves have been considered in the proposed model. The proposed easy to implement relation describes the intensity simply as a function of moment magnitude, source to site distance and focal depth. The prediction capability of the proposed model is assessed by means of residuals analysis. Prediction results have been compared with those of other intensity prediction models for Italy, Turkey, Iran and central Asia. The results indicate the higher attenuation rate for the study area in distances less than 70km.

  4. Maternal Moderate Physical Training during Pregnancy Attenuates the Effects of a Low-Protein Diet on the Impaired Secretion of Insulin in Rats: Potential Role for Compensation of Insulin Resistance and Preventing Gestational Diabetes Mellitus

    Directory of Open Access Journals (Sweden)

    Carol Góis Leandro

    2012-01-01

    Full Text Available The effects of pregestational and gestational low-to-moderate physical training on insulin secretion in undernourished mothers were evaluated. Virgin female Wistar rats were divided into four groups as follows: control (C, n=5; trained (T, n=5; low-protein diet (LP, n=5; trained with a low-protein diet (T + LP, n=5. Trained rats ran on a treadmill over a period of 4 weeks before mate (5 days week−1 and 60 min day−1, at 65% of VO2max. At pregnancy, the intensity and duration of the exercise were reduced. Low-protein groups were provided with an 8% casein diet, and controls were provided with a 17% casein diet. At third day after delivery, mothers and pups were killed and islets were isolated by collagenase digestion of pancreas and incubated for a further 1 h with medium containing 5.6 or 16.7 mM glucose. T mothers showed increased insulin secretion by isolated islets incubated with 16.7 mM glucose, whereas LP group showed reduced secretion of insulin by isolated islets when compared with both C and LP + T groups. Physical training before and during pregnancy attenuated the effects of a low-protein diet on the secretion of insulin, suggesting a potential role for compensation of insulin resistance and preventing gestational diabetes mellitus.

  5. PHYSICS

    CERN Multimedia

    D. Acosta

    2010-01-01

    A remarkable amount of progress has been made in Physics since the last CMS Week in June given the exponential growth in the delivered LHC luminosity. The first major milestone was the delivery of a variety of results to the ICHEP international conference held in Paris this July. For this conference, CMS prepared 15 Physics Analysis Summaries on physics objects and 22 Summaries on new and interesting physics measurements that exploited the luminosity recorded by the CMS detector. The challenge was incorporating the largest batch of luminosity that was delivered only days before the conference (300 nb-1 total). The physics covered from this initial running period spanned hadron production measurements, jet production and properties, electroweak vector boson production, and even glimpses of the top quark. Since then, the accumulated integrated luminosity has increased by a factor of more than 100, and all groups have been working tremendously hard on analysing this dataset. The September Physics Week was held ...

  6. PHYSICS

    CERN Multimedia

    J. Incandela

    There have been numerous developments in the physics area since the September CMS week. The biggest single event was the Physics/Trigger week in the end of Octo¬ber, whereas in terms of ongoing activities the “2007 analyses” went into high gear. This was in parallel with participation in CSA07 by the physics groups. On the or¬ganizational side, the new conveners of the physics groups have been selected, and a new database for man¬aging physics analyses has been deployed. Physics/Trigger week The second Physics-Trigger week of 2007 took place during the week of October 22-26. The first half of the week was dedicated to working group meetings. The ple¬nary Joint Physics-Trigger meeting took place on Wednesday afternoon and focused on the activities of the new Trigger Studies Group (TSG) and trigger monitoring. Both the Physics and Trigger organizations are now focused on readiness for early data-taking. Thus, early trigger tables and preparations for calibr...

  7. PHYSICS

    CERN Multimedia

    P. Sphicas

    The CPT project came to an end in December 2006 and its original scope is now shared among three new areas, namely Computing, Offline and Physics. In the physics area the basic change with respect to the previous system (where the PRS groups were charged with detector and physics object reconstruction and physics analysis) was the split of the detector PRS groups (the old ECAL-egamma, HCAL-jetMET, Tracker-btau and Muons) into two groups each: a Detector Performance Group (DPG) and a Physics Object Group. The DPGs are now led by the Commissioning and Run Coordinator deputy (Darin Acosta) and will appear in the correspond¬ing column in CMS bulletins. On the physics side, the physics object groups are charged with the reconstruction of physics objects, the tuning of the simulation (in collaboration with the DPGs) to reproduce the data, the provision of code for the High-Level Trigger, the optimization of the algorithms involved for the different physics analyses (in collaboration with the analysis gr...

  8. PHYSICS

    CERN Multimedia

    Submitted by

    Physics Week: plenary meeting on physics groups plans for startup (14–15 May 2008) The Physics Objects (POG) and Physics Analysis (PAG) Groups presented their latest developments at the plenary meeting during the Physics Week. In the presentations particular attention was given to startup plans and readiness for data-taking. Many results based on the recent cosmic run were shown. A special Workshop on SUSY, described in a separate section, took place the day before the plenary. At the meeting, we had also two special DPG presentations on “Tracker and Muon alignment with CRAFT” (Ernesto Migliore) and “Calorimeter studies with CRAFT” (Chiara Rovelli). We had also a report from Offline (Andrea Rizzi) and Computing (Markus Klute) on the San Diego Workshop, described elsewhere in this bulletin. Tracking group (Boris Mangano). The level of sophistication of the tracking software increased significantly over the last few months: V0 (K0 and Λ) reconstr...

  9. Attenuation correction for SPECT

    International Nuclear Information System (INIS)

    Hosoba, Minoru

    1986-01-01

    Attenuation correction is required for the reconstruction of a quantitative SPECT image. A new method for detecting body contours, which are important for the correction of tissue attenuation, is presented. The effect of body contours, detected by the newly developed method, on the reconstructed images was evaluated using various techniques for attenuation correction. The count rates in the specified region of interest in the phantom image by the Radial Post Correction (RPC) method, the Weighted Back Projection (WBP) method, Chang's method were strongly affected by the accuracy of the contours, as compared to those by Sorenson's method. To evaluate the effect of non-uniform attenuators on the cardiac SPECT, computer simulation experiments were performed using two types of models, the uniform attenuator model (UAM) and the non-uniform attenuator model (NUAM). The RPC method showed the lowest relative percent error (%ERROR) in UAM (11 %). However, 20 to 30 percent increase in %ERROR was observed for NUAM reconstructed with the RPC, WBP, and Chang's methods. Introducing an average attenuation coefficient (0.12/cm for Tc-99m and 0.14/cm for Tl-201) in the RPC method decreased %ERROR to the levels for UAM. Finally, a comparison between images, which were obtained by 180 deg and 360 deg scans and reconstructed from the RPC method, showed that the degree of the distortion of the contour of the simulated ventricles in the 180 deg scan was 15 % higher than that in the 360 deg scan. (Namekawa, K.)

  10. PHYSICS

    CERN Multimedia

    D. Futyan

    A lot has transpired on the “Physics” front since the last CMS Bulletin. The summer was filled with preparations of new Monte Carlo samples based on CMSSW_3, the finalization of all the 10 TeV physics analyses [in total 50 analyses were approved] and the preparations for the Physics Week in Bologna. A couple weeks later, the “October Exercise” commenced and ran through an intense two-week period. The Physics Days in October were packed with a number of topics that are relevant to data taking, in a number of “mini-workshops”: the luminosity measurement, the determination of the beam spot and the measurement of the missing transverse energy (MET) were the three main topics.  Physics Week in Bologna The second physics week in 2009 took place in Bologna, Italy, on the week of Sep 7-11. The aim of the week was to review and establish how ready we are to do physics with the early collisions at the LHC. The agenda of the week was thus pac...

  11. PHYSICS

    CERN Multimedia

    D. Futyan

    A lot has transpired on the “Physics” front since the last CMS Bulletin. The summer was filled with preparations of new Monte Carlo samples based on CMSSW_3, the finalization of all the 10 TeV physics analyses [in total 50 analyses were approved] and the preparations for the Physics Week in Bologna. A couple weeks later, the “October Exercise” commenced and ran through an intense two-week period. The Physics Days in October were packed with a number of topics that are relevant to data taking, in a number of “mini-workshops”: the luminosity measurement, the determination of the beam spot and the measurement of the missing transverse energy (MET) were the three main topics.   Physics Week in Bologna The second physics week in 2009 took place in Bologna, Italy, on the week of Sep 7-11. The aim of the week was to review and establish (we hoped) the readiness of CMS to do physics with the early collisions at the LHC. The agenda of the...

  12. Landing gear noise attenuation

    Science.gov (United States)

    Moe, Jeffrey W. (Inventor); Whitmire, Julia (Inventor); Kwan, Hwa-Wan (Inventor); Abeysinghe, Amal (Inventor)

    2011-01-01

    A landing gear noise attenuator mitigates noise generated by airframe deployable landing gear. The noise attenuator can have a first position when the landing gear is in its deployed or down position, and a second position when the landing gear is in its up or stowed position. The noise attenuator may be an inflatable fairing that does not compromise limited space constraints associated with landing gear retraction and stowage. A truck fairing mounted under a truck beam can have a compliant edge to allow for non-destructive impingement of a deflected fire during certain conditions.

  13. PHYSICS

    CERN Multimedia

    J. Incandela

    The all-plenary format of the CMS week in Cyprus gave the opportunity to the conveners of the physics groups to present the plans of each physics analysis group for tackling early physics analyses. The presentations were complete, so all are encouraged to browse through them on the Web. There is a wealth of information on what is going on, by whom and on what basis and priority. The CMS week was followed by two CMS “physics events”, the ICHEP08 days and the physics days in July. These were two weeks dedicated to either the approval of all the results that would be presented at ICHEP08, or to the review of all the other Monte-Carlo based analyses that were carried out in the context of our preparations for analysis with the early LHC data (the so-called “2008 analyses”). All this was planned in the context of the beginning of a ramp down of these Monte Carlo efforts, in anticipation of data.  The ICHEP days are described below (agenda and talks at: http://indic...

  14. PHYSICS

    CERN Multimedia

    Joe Incandela

    There have been two plenary physics meetings since the December CMS week. The year started with two workshops, one on the measurements of the Standard Model necessary for “discovery physics” as well as one on the Physics Analysis Toolkit (PAT). Meanwhile the tail of the “2007 analyses” is going through the last steps of approval. It is expected that by the end of January all analyses will have converted to using the data from CSA07 – which include the effects of miscalibration and misalignment. January Physics Days The first Physics Days of 2008 took place on January 22-24. The first two days were devoted to comprehensive re¬ports from the Detector Performance Groups (DPG) and Physics Objects Groups (POG) on their planning and readiness for early data-taking followed by approvals of several recent studies. Highlights of POG presentations are included below while the activities of the DPGs are covered elsewhere in this bulletin. January 24th was devo...

  15. Physics

    CERN Document Server

    Cullen, Katherine

    2005-01-01

    Defined as the scientific study of matter and energy, physics explains how all matter behaves. Separated into modern and classical physics, the study attracts both experimental and theoretical physicists. From the discovery of the process of nuclear fission to an explanation of the nature of light, from the theory of special relativity to advancements made in particle physics, this volume profiles 10 pioneers who overcame tremendous odds to make significant breakthroughs in this heavily studied branch of science. Each chapter contains relevant information on the scientist''s childhood, research, discoveries, and lasting contributions to the field and concludes with a chronology and a list of print and Internet references specific to that individual.

  16. PHYSICS

    CERN Multimedia

    Guenther Dissertori

    The time period between the last CMS week and this June was one of intense activity with numerous get-together targeted at addressing specific issues on the road to data-taking. The two series of workshops, namely the “En route to discoveries” series and the “Vertical Integration” meetings continued.   The first meeting of the “En route to discoveries” sequence (end 2007) had covered the measurements of the Standard Model signals as necessary prerequisite to any claim of signals beyond the Standard Model. The second meeting took place during the Feb CMS week and concentrated on the commissioning of the Physics Objects, whereas the third occurred during the April Physics Week – and this time the theme was the strategy for key new physics signatures. Both of these workshops are summarized below. The vertical integration meetings also continued, with two DPG-physics get-togethers on jets and missing ET and on electrons and photons. ...

  17. PHYSICS

    CERN Multimedia

    Chris Hill

    2012-01-01

    The months that have passed since the last CMS Bulletin have been a very busy and exciting time for CMS physics. We have gone from observing the very first 8TeV collisions produced by the LHC to collecting a dataset of the collisions that already exceeds that recorded in all of 2011. All in just a few months! Meanwhile, the analysis of the 2011 dataset and publication of the subsequent results has continued. These results come from all the PAGs in CMS, including searches for the Higgs boson and other new phenomena, that have set the most stringent limits on an ever increasing number of models of physics beyond the Standard Model including dark matter, Supersymmetry, and TeV-scale gravity scenarios, top-quark physics where CMS has overtaken the Tevatron in the precision of some measurements, and bottom-quark physics where CMS made its first discovery of a new particle, the Ξ*0b baryon (candidate event pictured below). Image 2:  A Ξ*0b candidate event At the same time POGs and PAGs...

  18. PHYSICS

    CERN Multimedia

    D. Acosta

    2011-01-01

    Since the last CMS Week, all physics groups have been extremely active on analyses based on the full 2010 dataset, with most aiming for a preliminary measurement in time for the winter conferences. Nearly 50 analyses were approved in a “marathon” of approval meetings during the first two weeks of March, and the total number of approved analyses reached 90. The diversity of topics is very broad, including precision QCD, Top, and electroweak measurements, the first observation of single Top production at the LHC, the first limits on Higgs production at the LHC including the di-tau final state, and comprehensive searches for new physics in a wide range of topologies (so far all with null results unfortunately). Most of the results are based on the full 2010 pp data sample, which corresponds to 36 pb-1 at √s = 7 TeV. This report can only give a few of the highlights of a very rich physics program, which is listed below by physics group...

  19. PHYSICS

    CERN Multimedia

    Darin Acosta

    2010-01-01

    The collisions last year at 900 GeV and 2.36 TeV provided the long anticipated collider data to the CMS physics groups. Quite a lot has been accomplished in a very short time. Although the delivered luminosity was small, CMS was able to publish its first physics paper (with several more in preparation), and commence the commissioning of physics objects for future analyses. Many new performance results have been approved in advance of this CMS Week. One remarkable outcome has been the amazing agreement between out-of-the-box data with simulation at these low energies so early in the commissioning of the experiment. All of this is testament to the hard work and preparation conducted beforehand by many people in CMS. These analyses could not have happened without the dedicated work of the full collaboration on building and commissioning the detector, computing, and software systems combined with the tireless work of many to collect, calibrate and understand the data and our detector. To facilitate the efficien...

  20. PHYSICS

    CERN Multimedia

    D. Acosta

    2010-01-01

    The Physics Groups are actively engaged on analyses of the first data from the LHC at 7 TeV, targeting many results for the ICHEP conference taking place in Paris this summer. The first large batch of physics approvals is scheduled for this CMS Week, to be followed by four more weeks of approvals and analysis updates leading to the start of the conference in July. Several high priority analysis areas were organized into task forces to ensure sufficient coverage from the relevant detector, object, and analysis groups in the preparation of these analyses. Already some results on charged particle correlations and multiplicities in 7 TeV minimum bias collisions have been approved. Only one small detail remains before ICHEP: further integrated luminosity delivered by the LHC! Beyond the Standard Model measurements that can be done with these data, the focus changes to the search for new physics at the TeV scale and for the Higgs boson in the period after ICHEP. Particle Flow The PFT group is focusing on the ...

  1. PHYSICS

    CERN Multimedia

    the PAG conveners

    2011-01-01

    The delivered LHC integrated luminosity of more than 1 inverse femtobarn by summer and more than 5 by the end of 2011 has been a gold mine for the physics groups. With 2011 data, we have submitted or published 14 papers, 7 others are in collaboration-wide review, and 75 Physics Analysis Summaries have been approved already. They add to the 73 papers already published based on the 2010 and 2009 datasets. Highlights from each physics analysis group are described below. Heavy ions Many important results have been obtained from the first lead-ion collision run in 2010. The published measurements include the first ever indications of Υ excited state suppression (PRL synopsis), long-range correlation in PbPb, and track multiplicity over a wide η range. Preliminary results include the first ever measurement of isolated photons (showing no modification), J/ψ suppression including the separation of the non-prompt component, further study of jet fragmentation, nuclear modification factor...

  2. PHYSICS

    CERN Multimedia

    L. Demortier

    Physics-wise, the CMS week in December was dominated by discussions of the analyses that will be carried out in the “next six months”, i.e. while waiting for the first LHC collisions.  As presented in December, analysis approvals based on Monte Carlo simulation were re-opened, with the caveat that for this work to be helpful to the goals of CMS, it should be carried out using the new software (CMSSW_2_X) and associated samples.  By the end of the week, the goal for the physics groups was set to be the porting of our physics commissioning methods and plans, as well as the early analyses (based an integrated luminosity in the range 10-100pb-1) into this new software. Since December, the large data samples from CMSSW_2_1 were completed. A big effort by the production group gave a significant number of events over the end-of-year break – but also gave out the first samples with the fast simulation. Meanwhile, as mentioned in December, the arrival of 2_2 meant that ...

  3. PHYSICS

    CERN Multimedia

    C. Hill

    2012-01-01

      2012 has started off as a very busy year for the CMS Physics Groups. Planning for the upcoming higher luminosity/higher energy (8 TeV) operation of the LHC and relatively early Rencontres de Moriond are the high-priority activities for the group at the moment. To be ready for the coming 8-TeV data, CMS has made a concerted effort to perform and publish analyses on the 5 fb−1 dataset recorded in 2011. This has resulted in the submission of 16 papers already, including nine on the search for the Higgs boson. In addition, a number of preliminary results on the 2011 dataset have been released to the public. The Exotica and SUSY groups approved several searches for new physics in January, such as searches for W′ and exotic highly ionising particles. These were highlighted at a CERN seminar given on 24th  January. Many more analyses, from all the PAGs, including the newly formed SMP (Standard Model Physics) and FSQ (Forward and Small-x QCD), were approved in February. The ...

  4. PHYSICS

    CERN Document Server

    C. Hill

    2012-01-01

      The period since the last CMS Bulletin has been historic for CMS Physics. The pinnacle of our physics programme was an observation of a new particle – a strong candidate for a Higgs boson – which has captured worldwide interest and made a profound impact on the very field of particle physics. At the time of the discovery announcement on 4 July, 2012, prominent signals were observed in the high-resolution H→γγ and H→ZZ(4l) modes. Corroborating excess was observed in the H→W+W– mode as well. The fermionic channel analyses (H→bb, H→ττ), however, yielded less than the Standard Model (SM) expectation. Collectively, the five channels established the signal with a significance of five standard deviations. With the exception of the diphoton channel, these analyses have all been updated in the last months and several new channels have been added. With improved analyses and more than twice the i...

  5. Radiofrequency attenuator and method

    Science.gov (United States)

    Warner, Benjamin P [Los Alamos, NM; McCleskey, T Mark [Los Alamos, NM; Burrell, Anthony K [Los Alamos, NM; Agrawal, Anoop [Tucson, AZ; Hall, Simon B [Palmerston North, NZ

    2009-01-20

    Radiofrequency attenuator and method. The attenuator includes a pair of transparent windows. A chamber between the windows is filled with molten salt. Preferred molten salts include quarternary ammonium cations and fluorine-containing anions such as tetrafluoroborate (BF.sub.4.sup.-), hexafluorophosphate (PF.sub.6.sup.-), hexafluoroarsenate (AsF.sub.6.sup.-), trifluoromethylsulfonate (CF.sub.3SO.sub.3.sup.-), bis(trifluoromethylsulfonyl)imide ((CF.sub.3SO.sub.2).sub.2N.sup.-), bis(perfluoroethylsulfonyl)imide ((CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-) and tris(trifluoromethylsulfonyl)methide ((CF.sub.3SO.sub.2).sub.3C.sup.-). Radicals or radical cations may be added to or electrochemically generated in the molten salt to enhance the RF attenuation.

  6. Attenuation coefficients of soils

    International Nuclear Information System (INIS)

    Martini, E.; Naziry, M.J.

    1989-01-01

    As a prerequisite to the interpretation of gamma-spectrometric in situ measurements of activity concentrations of soil radionuclides the attenuation of 60 to 1332 keV gamma radiation by soil samples varying in water content and density has been investigated. A useful empirical equation could be set up to describe the dependence of the mass attenuation coefficient upon photon energy for soil with a mean water content of 10%, with the results comparing well with data in the literature. The mean density of soil in the GDR was estimated at 1.6 g/cm 3 . This value was used to derive the linear attenuation coefficients, their range of variation being 10%. 7 figs., 5 tabs. (author)

  7. PHYSICS

    CERN Multimedia

    J. D'Hondt

    The Electroweak and Top Quark Workshop (16-17th of July) A Workshop on Electroweak and Top Quark Physics, dedicated on early measurements, took place on 16th-17th July. We had more than 40 presentations at the Workshop, which was an important milestone for 2007 physics analyses in the EWK and TOP areas. The Standard Model has been tested empirically by many previous experiments. Observables which are nowadays known with high precision will play a major role for data-based CMS calibrations. A typical example is the use of the Z to monitor electron and muon reconstruction in di-lepton inclusive samples. Another example is the use of the W mass as a constraint for di-jets in the kinematic fitting of top-quark events, providing information on the jet energy scale. The predictions of the Standard Model, for what concerns proton collisions at the LHC, are accurate to a level that the production of W/Z and top-quark events can be used as a powerful tool to commission our experiment. On the other hand the measure...

  8. PHYSICS

    CERN Multimedia

    Christopher Hill

    2013-01-01

    Since the last CMS Bulletin, the CMS Physics Analysis Groups have completed more than 70 new analyses, many of which are based on the complete Run 1 dataset. In parallel the Snowmass whitepaper on projected discovery potential of CMS for HL-LHC has been completed, while the ECFA HL-LHC future physics studies has been summarised in a report and nine published benchmark analyses. Run 1 summary studies on b-tag and jet identification, quark-gluon discrimination and boosted topologies have been documented in BTV-13-001 and JME-13-002/005/006, respectively. The new tracking alignment and performance papers are being prepared for submission as well. The Higgs analysis group produced several new results including the search for ttH with H decaying to ZZ, WW, ττ+bb (HIG-13-019/020) where an excess of ~2.5σ is observed in the like-sign di-muon channel, and new searches for high-mass Higgs bosons (HIG-13-022). Search for invisible Higgs decays have also been performed both using the associ...

  9. PHYSICS

    CERN Multimedia

    C. Hill

    2013-01-01

    In the period since the last CMS Bulletin, the LHC – and CMS – have entered LS1. During this time, CMS Physics Analysis Groups have performed more than 40 new analyses, many of which are based on the complete 8 TeV dataset delivered by the LHC in 2012 (and in some cases on the full Run 1 dataset). These results were shown at, and well received by, several high-profile conferences in the spring of 2013, including the inaugural meeting of the Large Hadron Collider    Physics Conference (LHCP) in Barcelona, and the 26th International Symposium on Lepton Photon Interactions at High Energies (LP) in San Francisco. In parallel, there have been significant developments in preparations for Run 2 of the LHC and on “future physics” studies for both Phase 1 and Phase 2 upgrades of the CMS detector. The Higgs analysis group produced five new results for LHCP including a new H-to-bb search in VBF production (HIG-13-011), ttH with H to γ&ga...

  10. PHYSICS

    CERN Multimedia

    C. Hill

    2013-01-01

    The period since the last CMS bulletin has seen the end of proton collisions at a centre-of-mass energy 8 TeV, a successful proton-lead collision run at 5 TeV/nucleon, as well as a “reference” proton run at 2.76 TeV. With these final LHC Run 1 datasets in hand, CMS Physics Analysis Groups have been busy analysing these data in preparation for the winter conferences. Moreover, despite the fact that the pp run only concluded in mid-December (and there was consequently less time to complete data analyses), CMS again made a strong showing at the Rencontres de Moriond in La Thuile (EW and QCD) where nearly 40 new results were presented. The highlight of these preliminary results was the eagerly anticipated updated studies of the properties of the Higgs boson discovered in July of last year. Meanwhile, preparations for Run 2 and physics performance studies for Phase 1 and Phase 2 upgrade scenarios are ongoing. The Higgs analysis group produced updated analyses on the full Run 1 dataset (~25 f...

  11. Computer-controlled attenuator.

    Science.gov (United States)

    Mitov, D; Grozev, Z

    1991-01-01

    Various possibilities for applying electronic computer-controlled attenuators for the automation of physiological experiments are considered. A detailed description is given of the design of a 4-channel computer-controlled attenuator, in two of the channels of which the output signal can change by a linear step, in the other two channels--by a logarithmic step. This, together with the existence of additional programmable timers, allows to automate a wide range of studies in different spheres of physiology and psychophysics, including vision and hearing.

  12. SEISMIC ATTENUATION FOR RESERVOIR CHARACTERIZATION

    Energy Technology Data Exchange (ETDEWEB)

    Joel Walls; M.T. Taner; Naum Derzhi; Gary Mavko; Jack Dvorkin

    2003-12-01

    We have developed and tested technology for a new type of direct hydrocarbon detection. The method uses inelastic rock properties to greatly enhance the sensitivity of surface seismic methods to the presence of oil and gas saturation. These methods include use of energy absorption, dispersion, and attenuation (Q) along with traditional seismic attributes like velocity, impedance, and AVO. Our approach is to combine three elements: (1) a synthesis of the latest rock physics understanding of how rock inelasticity is related to rock type, pore fluid types, and pore microstructure, (2) synthetic seismic modeling that will help identify the relative contributions of scattering and intrinsic inelasticity to apparent Q attributes, and (3) robust algorithms that extract relative wave attenuation attributes from seismic data. This project provides: (1) Additional petrophysical insight from acquired data; (2) Increased understanding of rock and fluid properties; (3) New techniques to measure reservoir properties that are not currently available; and (4) Provide tools to more accurately describe the reservoir and predict oil location and volumes. These methodologies will improve the industry's ability to predict and quantify oil and gas saturation distribution, and to apply this information through geologic models to enhance reservoir simulation. We have applied for two separate patents relating to work that was completed as part of this project.

  13. Natural attenuation of herbicides

    DEFF Research Database (Denmark)

    Tuxen, Nina; Højberg, Anker Lajer; Broholm, Mette Martina

    2002-01-01

    A field injection experiment in a sandy, aerobic aquifer showed that two phenoxy acids MCPP (mecoprop) and dichlorprop were degraded within I in downgradient of the injection wells after an apparent lag period. The plume development and microbial measurements indicated that microbial growth gover....... The observations may be important for application of natural attenuation as a remedy in field scale systems....

  14. Measured attenuation correction methods

    International Nuclear Information System (INIS)

    Ostertag, H.; Kuebler, W.K.; Doll, J.; Lorenz, W.J.

    1989-01-01

    Accurate attenuation correction is a prerequisite for the determination of exact local radioactivity concentrations in positron emission tomography. Attenuation correction factors range from 4-5 in brain studies to 50-100 in whole body measurements. This report gives an overview of the different methods of determining the attenuation correction factors by transmission measurements using an external positron emitting source. The long-lived generator nuclide 68 Ge/ 68 Ga is commonly used for this purpose. The additional patient dose from the transmission source is usually a small fraction of the dose due to the subsequent emission measurement. Ring-shaped transmission sources as well as rotating point or line sources are employed in modern positron tomographs. By masking a rotating line or point source, random and scattered events in the transmission scans can be effectively suppressed. The problems of measured attenuation correction are discussed: Transmission/emission mismatch, random and scattered event contamination, counting statistics, transmission/emission scatter compensation, transmission scan after administration of activity to the patient. By using a double masking technique simultaneous emission and transmission scans become feasible. (orig.)

  15. PHYSICS

    CERN Multimedia

    V.Ciulli

    2011-01-01

    The main programme of the Physics Week held between 16th and 20th May was a series of topology-oriented workshops on di-leptons, di-photons, inclusive W, and all-hadronic final states. The goal of these workshops was to reach a common understanding for the set of objects (ID, cleaning...), the handling of pile-up, calibration, efficiency and purity determination, as well as to revisit critical common issues such as the trigger. Di-lepton workshop Most analysis groups use a di-lepton trigger or a combination of single and di-lepton triggers in 2011. Some groups need to collect leptons with as low PT as possible with strong isolation and identification requirements as for Higgs into WW at low mass, others with intermediate PT values as in Drell-Yan studies, or high PT as in the Exotica group. Electron and muon reconstruction, identification and isolation, was extensively described in the workshop. For electrons, VBTF selection cuts for low PT and HEEP cuts for high PT were discussed, as well as more complex d...

  16. Nutrient-rich dairy proteins improve appendicular skeletal muscle mass and physical performance, and attenuate the loss of muscle strength in older men and women subjects: a single-blind randomized clinical trial

    Directory of Open Access Journals (Sweden)

    Alemán-Mateo H

    2014-09-01

    Full Text Available Heliodoro Alemán-Mateo,1 Virginia Ramírez Carreón,1 Liliana Macías,1 Humberto Astiazaran-García,1 Ana Cristina Gallegos-Aguilar,1 José Rogelio Ramos Enríquez2 1Coordinación de Nutrición, Centro de Investigación en Alimentación y Desarrollo, A.C., 2Laboratorio de Análisis Clínicos e Investigación, Departamento de Ciencias Químico Biológicas, Universidad de Sonora, Hermosillo, Mexico Background: At present, it is unknown whether the use of nutrient-rich dairy proteins improves the markers of sarcopenia syndrome. Therefore, our proposal was to investigate whether ­adding 210 g of ricotta cheese daily would improve skeletal muscle mass, handgrip strength, and ­physical performance in non-sarcopenic older subjects.Subjects and methods: This was a single-blind randomized clinical trial that included two homogeneous, randomized groups of men and women over 60 years of age. Participants in the intervention group were asked to consume their habitual diet but add 210 g of ricotta cheese (IG/HD + RCH, while the control group was instructed to consume only their habitual diet (CG/HD. Basal and 12-week follow-up measurements included appendicular skeletal muscle mass (ASMM by dual-energy X-ray absorptiometry, handgrip strength by a handheld dynamometer, and physical performance using the short physical performance battery (SPPB and the stair-climb power test (SCPT. The main outcomes were relative changes in ASMM, strength, SPPB, and SCPT.Results: ASMM increased in the IG/HD + RCH (0.6±3.5 kg, but decreased in the CG/HD (–1.0±2.6. The relative change between groups was statistically significant (P=0.009. The relative change in strength in both groups was negative, but the loss of muscle strength was more pronounced in CG/HD, though in this regard statistical analysis found only a tendency (P=0.07. The relative change in the balance-test scores was positive for the IG/HD + RCH, while in the CG/HD it was negative, as those individuals had

  17. Photon attenuation by intensifying screens

    International Nuclear Information System (INIS)

    Holje, G.

    1983-01-01

    The photon attenuation by intensifying screens of different chemical composition has been determined. The attenuation of photons between 20 keV and 120 keV was measured by use of a multi-channel analyzer and a broad bremsstrahlung distribution. The attenuation by the intensifying screens was hereby determined simultaneously at many different monoenergetic photon energies. Experimentally determined attenuations were found to agree well with attenuation calculated from mass attenuation coefficients. The attenuation by the screens was also determined at various bremsstrahlung distributions, simulating those occurring behind the patient in various diagnostic X-ray examinations. The high attenuation in some of the intensifying screens form the basis for an analysis of the construction of asymmetric screen pairs. Single screen systems are suggested as a favourable alternative to thick screen pair systems. (Author)

  18. Enhanced Attenuation: Chlorinated Organics

    Science.gov (United States)

    2008-04-01

    attenuation capacity of the aquifer downgradient from the source (e.g., permeable reactive barriers or phytoremediation ) Selection of EA remedies should be...prevalence and/or mobility of nitrate and sulfate compounds and/or metals such as iron, manganese, chromium, copper, and arsenic . Furthermore, in...ranging from very aggressive source destruction and removal methods to less energy-intensive methods, such as phytoremediation . In many cases, it

  19. Control algorithms for dynamic attenuators

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Scott S., E-mail: sshsieh@stanford.edu [Department of Radiology, Stanford University, Stanford, California 94305 and Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Pelc, Norbert J. [Department of Radiology, Stanford University, Stanford California 94305 and Department of Bioengineering, Stanford University, Stanford, California 94305 (United States)

    2014-06-15

    Purpose: The authors describe algorithms to control dynamic attenuators in CT and compare their performance using simulated scans. Dynamic attenuators are prepatient beam shaping filters that modulate the distribution of x-ray fluence incident on the patient on a view-by-view basis. These attenuators can reduce dose while improving key image quality metrics such as peak or mean variance. In each view, the attenuator presents several degrees of freedom which may be individually adjusted. The total number of degrees of freedom across all views is very large, making many optimization techniques impractical. The authors develop a theory for optimally controlling these attenuators. Special attention is paid to a theoretically perfect attenuator which controls the fluence for each ray individually, but the authors also investigate and compare three other, practical attenuator designs which have been previously proposed: the piecewise-linear attenuator, the translating attenuator, and the double wedge attenuator. Methods: The authors pose and solve the optimization problems of minimizing the mean and peak variance subject to a fixed dose limit. For a perfect attenuator and mean variance minimization, this problem can be solved in simple, closed form. For other attenuator designs, the problem can be decomposed into separate problems for each view to greatly reduce the computational complexity. Peak variance minimization can be approximately solved using iterated, weighted mean variance (WMV) minimization. Also, the authors develop heuristics for the perfect and piecewise-linear attenuators which do not requirea priori knowledge of the patient anatomy. The authors compare these control algorithms on different types of dynamic attenuators using simulated raw data from forward projected DICOM files of a thorax and an abdomen. Results: The translating and double wedge attenuators reduce dose by an average of 30% relative to current techniques (bowtie filter with tube current

  20. Control algorithms for dynamic attenuators

    International Nuclear Information System (INIS)

    Hsieh, Scott S.; Pelc, Norbert J.

    2014-01-01

    Purpose: The authors describe algorithms to control dynamic attenuators in CT and compare their performance using simulated scans. Dynamic attenuators are prepatient beam shaping filters that modulate the distribution of x-ray fluence incident on the patient on a view-by-view basis. These attenuators can reduce dose while improving key image quality metrics such as peak or mean variance. In each view, the attenuator presents several degrees of freedom which may be individually adjusted. The total number of degrees of freedom across all views is very large, making many optimization techniques impractical. The authors develop a theory for optimally controlling these attenuators. Special attention is paid to a theoretically perfect attenuator which controls the fluence for each ray individually, but the authors also investigate and compare three other, practical attenuator designs which have been previously proposed: the piecewise-linear attenuator, the translating attenuator, and the double wedge attenuator. Methods: The authors pose and solve the optimization problems of minimizing the mean and peak variance subject to a fixed dose limit. For a perfect attenuator and mean variance minimization, this problem can be solved in simple, closed form. For other attenuator designs, the problem can be decomposed into separate problems for each view to greatly reduce the computational complexity. Peak variance minimization can be approximately solved using iterated, weighted mean variance (WMV) minimization. Also, the authors develop heuristics for the perfect and piecewise-linear attenuators which do not requirea priori knowledge of the patient anatomy. The authors compare these control algorithms on different types of dynamic attenuators using simulated raw data from forward projected DICOM files of a thorax and an abdomen. Results: The translating and double wedge attenuators reduce dose by an average of 30% relative to current techniques (bowtie filter with tube current

  1. Control algorithms for dynamic attenuators.

    Science.gov (United States)

    Hsieh, Scott S; Pelc, Norbert J

    2014-06-01

    The authors describe algorithms to control dynamic attenuators in CT and compare their performance using simulated scans. Dynamic attenuators are prepatient beam shaping filters that modulate the distribution of x-ray fluence incident on the patient on a view-by-view basis. These attenuators can reduce dose while improving key image quality metrics such as peak or mean variance. In each view, the attenuator presents several degrees of freedom which may be individually adjusted. The total number of degrees of freedom across all views is very large, making many optimization techniques impractical. The authors develop a theory for optimally controlling these attenuators. Special attention is paid to a theoretically perfect attenuator which controls the fluence for each ray individually, but the authors also investigate and compare three other, practical attenuator designs which have been previously proposed: the piecewise-linear attenuator, the translating attenuator, and the double wedge attenuator. The authors pose and solve the optimization problems of minimizing the mean and peak variance subject to a fixed dose limit. For a perfect attenuator and mean variance minimization, this problem can be solved in simple, closed form. For other attenuator designs, the problem can be decomposed into separate problems for each view to greatly reduce the computational complexity. Peak variance minimization can be approximately solved using iterated, weighted mean variance (WMV) minimization. Also, the authors develop heuristics for the perfect and piecewise-linear attenuators which do not require a priori knowledge of the patient anatomy. The authors compare these control algorithms on different types of dynamic attenuators using simulated raw data from forward projected DICOM files of a thorax and an abdomen. The translating and double wedge attenuators reduce dose by an average of 30% relative to current techniques (bowtie filter with tube current modulation) without

  2. Scatter and attenuation correction in SPECT

    International Nuclear Information System (INIS)

    Ljungberg, Michael

    2004-01-01

    The adsorbed dose is related to the activity uptake in the organ and its temporal distribution. Measured count rate with scintillation cameras is related to activity through the system sensitivity, cps/MBq. By accounting for physical processes and imaging limitations we can measure the activity at different time points. Correction for physical factor, such as attenuation and scatter is required for accurate quantitation. Both planar and SPECT imaging can be used to estimate activities for radiopharmaceutical dosimetry. Planar methods have been the most widely used but is a 2D technique. With accurate modelling for imagine in iterative reconstruction, SPECT methods will prove to be more accurate

  3. Transport and attenuation of radiations

    CERN Document Server

    Nimal, J C

    2003-01-01

    This article treats of the calculation methods used for the dimensioning of the protections against radiations. The method consists in determining for a given point the flux of particles coming from a source at a given time. A strong attenuation (of about some few mu Sv.h sup - sup 1) is in general expected between the source and the areas accessible to the personnel or the public. The calculation has to take into account a huge number of radiation-matter interactions and to solve the integral-differential transport equation which links the particles flux to the source. Several methods exist from the simplified physical model with numerical developments to the more or less precise resolution of the transport equation. These methods allows also the calculation of the uncertainties of equivalent dose rates, heat sources, structure damages using the data covariances (efficient cross-sections, modeling, etc..): 1 - transport equation; 2 - Monte-Carlo method; 3 - semi-numerical methods S sub N; 4 - methods based o...

  4. Ultrasonic attenuation in superconducting zinc

    International Nuclear Information System (INIS)

    Auluck, S.

    1978-01-01

    The differences in the Zn ultrasonic attenuation data of different workers are analyzed. The superconducting energy gaps deduced from our analysis of the ultrasonic-attenuation data of Cleavelin and Marshall are consistent with the gaps deduced from the knowledge of the Fermi surface and the electron-phonon mass enhancement factor

  5. Physical physics

    CERN Document Server

    Schulman, Mark

    2006-01-01

    "Protons, electrons, positrons, quarks, gluons, muons, shmuons! I should have paid better attention to my high scholl physics teacher. If I had, maybe I could have understood even a fration of what Israeli particle physicist Giora Mikenberg was talking about when explaining his work on the world's largest science experiment." (2 pages)

  6. Quantitative SPECT brain imaging: Effects of attenuation and detector response

    International Nuclear Information System (INIS)

    Gilland, D.R.; Jaszczak, R.J.; Bowsher, J.E.; Turkington, T.G.; Liang, Z.; Greer, K.L.; Coleman, R.E.

    1993-01-01

    Two physical factors that substantially degrade quantitative accuracy in SPECT imaging of the brain are attenuation and detector response. In addition to the physical factors, random noise in the reconstructed image can greatly affect the quantitative measurement. The purpose of this work was to implement two reconstruction methods that compensate for attenuation and detector response, a 3D maximum likelihood-EM method (ML) and a filtered backprojection method (FB) with Metz filter and Chang attenuation compensation, and compare the methods in terms of quantitative accuracy and image noise. The methods were tested on simulated data of the 3D Hoffman brain phantom. The simulation incorporated attenuation and distance-dependent detector response. Bias and standard deviation of reconstructed voxel intensities were measured in the gray and white matter regions. The results with ML showed that in both the gray and white matter regions as the number of iterations increased, bias decreased and standard deviation increased. Similar results were observed with FB as the Metz filter power increased. In both regions, ML had smaller standard deviation than FB for a given bias. Reconstruction times for the ML method have been greatly reduced through efficient coding, limited source support, and by computing attenuation factors only along rays perpendicular to the detector

  7. Physical Properties of P.V.C. Attenuated Network Copolymers Produced by Ionizing Radiation; Proprietes physiques des copolymeres obtenus sous l'action de rayonnements ionisants et dont le reseau est attenue par l'effet du chlorure de polyvinyle; Fizicheskie svojstva polivinilkhloridnykh obednennykh tsepej sopolimerov, poluchennykh v rezul'tate vozdejstviya ioniziruyushchej radiatsii; Propiedades fisicas de los copolimeros de redes atenuadas por cloruro de polivinilo obtenidos por irradiacion

    Energy Technology Data Exchange (ETDEWEB)

    Pinner, S H [Tube Investments Research Laboratories, Hinxton Hall, Cambridge (United Kingdom)

    1960-07-15

    The cross-linking of polyvinyl chloride with ionizing radiation poses special problems. Due to rather unfavourable cross-linking and dislinking parameters for this polymer, the radiation doses necessary for high cross-link densities are uneconomicall y large and discolouration and dehydrohalogenatio n are simultaneously produced. These difficulties have been overcome by the incorporation into the P. V. C., prior to irradiation, of diallyl and triallyl esters. Heavily cross-linked products are thereby obtained with relatively low doses of ionizing radiation. Examination of the physical properties of the products suggests that these are not simply graft copolymers, which term normally implies the presence of long branch chains, but are polymer attenuated allyl networks. In these materials, the desirable properties of the parent polymer and of the allyl network are combined. The tensile strength, modulus and elongation of the attenuated network copolymers are presented and discussed as a function of temperature and of the concentration and functionality of the allyl ester. Reference is also made to the swelling and chemical resistance of the products. (author) [French] La reticulation du chlorure de polyvinyle sous l'action des rayonnements ionisants pose des problemes particuliers. Les parametres de reticulation et de degradation etant plutot defavorables pour ce polymere, les doses d'irradiation necessaires a l'obtention de fortes densites de pontage sont trop elevees pour donner des resultats economiquement interessants; elles provoquent simultanement la decoloration et la deshalogenhydratation. Il a ete possible de surmonter ces difficultes par introduction d'esters diallyliques et triallyliques dans le chlorure de polyvinyle, avant irradiation. Ce procede permet d'obtenir au moyen de doses d'irradiation relativement faibles des produits fortement reticules. L'etude des proprietes physiques de ces produits montre qu'il s'agit non pas de simples copolymeres greffes

  8. Attenuation in Superconducting Circular Waveguides

    Directory of Open Access Journals (Sweden)

    K. H. Yeap

    2016-09-01

    Full Text Available We present an analysis on wave propagation in superconducting circular waveguides. In order to account for the presence of quasiparticles in the intragap states of a superconductor, we employ the characteristic equation derived from the extended Mattis-Bardeen theory to compute the values of the complex conductivity. To calculate the attenuation in a circular waveguide, the tangential fields at the boundary of the wall are first matched with the electrical properties (which includes the complex conductivity of the wall material. The matching of fields with the electrical properties results in a set of transcendental equations which is able to accurately describe the propagation constant of the fields. Our results show that although the attenuation in the superconducting waveguide above cutoff (but below the gap frequency is finite, it is considerably lower than that in a normal waveguide. Above the gap frequency, however, the attenuation in the superconducting waveguide increases sharply. The attenuation eventually surpasses that in a normal waveguide. As frequency increases above the gap frequency, Cooper pairs break into quasiparticles. Hence, we attribute the sharp rise in attenuation to the increase in random collision of the quasiparticles with the lattice structure.

  9. Attenuation and Velocity Structure in Spain and Morocco: Distinguishing Between Water, Temperature, and Partial Melt

    Science.gov (United States)

    Bezada, M. J.; Humphreys, E.

    2014-12-01

    Temperature, melt fraction, and water content affect seismic velocity and attenuation differently. Both are sensitive to temperature, but velocity is more sensitive to melt fraction and attenuation is thought to be more sensitive to water content. For these reasons, combining attenuation measurements with tomographic imaging of velocity structure can help untangle these fields and better resolve lithospheric structure and physical state. We map variations in attenuation beneath Spain and northern Morocco using teleseismic data generated by more than a dozen teleseismic deep-focus earthquakes recorded on a dense array of stations. For each event, we first estimate the source from the best quality recordings. We then apply an attenuation operator to the source estimate, using a range of t* values, to match the record at each station. We invert for a smooth map of t* from the ensemble of measurements. The spatial patterns in t* correlate very well with the tectonic domains in Spain and Morocco. In particular, areas in Spain that resisted deformation during the Variscan and Alpine orogenies produce very little attenuation. Comparing the attenuation map with seismic velocity structure we find that, in Morocco, some areas with strong low-velocity anomalies and recent volcanism do not cause high attenuation. These observations suggest that water content is a more likely cause for seismic attenuation in the study area than temperature, and that the non-attenuative low-velocity anomalies in Morocco are produced by partial mel.

  10. Josephson tunnel junction microwave attenuator

    DEFF Research Database (Denmark)

    Koshelets, V. P.; Shitov, S. V.; Shchukin, A. V.

    1993-01-01

    A new element for superconducting electronic circuitry-a variable attenuator-has been proposed, designed, and successfully tested. The principle of operation is based on the change in the microwave impedance of a superconductor-insulator-superconductor (SIS) Josephson tunnel junction when dc biased...... at different points in the current-voltage characteristic. Both numerical calculations based on the Tien-Gordon theory and 70-GHz microwave experiments have confirmed the wide dynamic range (more than 15-dB attenuation for one stage) and the low insertion loss in the ''open'' state. The performance of a fully...

  11. Statistical modeling of optical attenuation measurements in continental fog conditions

    Science.gov (United States)

    Khan, Muhammad Saeed; Amin, Muhammad; Awan, Muhammad Saleem; Minhas, Abid Ali; Saleem, Jawad; Khan, Rahimdad

    2017-03-01

    Free-space optics is an innovative technology that uses atmosphere as a propagation medium to provide higher data rates. These links are heavily affected by atmospheric channel mainly because of fog and clouds that act to scatter and even block the modulated beam of light from reaching the receiver end, hence imposing severe attenuation. A comprehensive statistical study of the fog effects and deep physical understanding of the fog phenomena are very important for suggesting improvements (reliability and efficiency) in such communication systems. In this regard, 6-months real-time measured fog attenuation data are considered and statistically investigated. A detailed statistical analysis related to each fog event for that period is presented; the best probability density functions are selected on the basis of Akaike information criterion, while the estimates of unknown parameters are computed by maximum likelihood estimation technique. The results show that most fog attenuation events follow normal mixture distribution and some follow the Weibull distribution.

  12. Gain attenuation of gated framing camera

    International Nuclear Information System (INIS)

    Xiao Shali; Liu Shenye; Cao Zhurong; Li Hang; Zhang Haiying; Yuan Zheng; Wang Liwei

    2009-01-01

    The theoretic model of framing camera's gain attenuation is analyzed. The exponential attenuation curve of the gain along the pulse propagation time is simulated. An experiment to measure the coefficient of gain attenuation based on the gain attenuation theory is designed. Experiment result shows that the gain follows an exponential attenuation rule with a quotient of 0.0249 nm -1 , the attenuation coefficient of the pulse is 0.00356 mm -1 . The loss of the pulse propagation along the MCP stripline is the leading reason of gain attenuation. But in the figure of a single stripline, the gain dose not follow the rule of exponential attenuation completely, instead, there is a gain increase at the stripline bottom. That is caused by the reflection of the pulse. The reflectance is about 24.2%. Combining the experiment and theory, which design of the stripline MCP can improved the gain attenuation. (authors)

  13. Patient position alters attenuation effects in multipinhole cardiac SPECT

    International Nuclear Information System (INIS)

    Timmins, Rachel; Ruddy, Terrence D.; Wells, R. Glenn

    2015-01-01

    Purpose: Dedicated cardiac cameras offer improved sensitivity over conventional SPECT cameras. Sensitivity gains are obtained by large numbers of detectors and novel collimator arrangements such as an array of multiple pinholes that focus on the heart. Pinholes lead to variable amounts of attenuation as a source is moved within the camera field of view. This study evaluated the effects of this variable attenuation on myocardial SPECT images. Methods: Computer simulations were performed for a set of nine point sources distributed in the left ventricular wall (LV). Sources were placed at the location of the heart in both an anthropomorphic and a water-cylinder computer phantom. Sources were translated in x, y, and z by up to 5 cm from the center. Projections were simulated with and without attenuation and the changes in attenuation were compared. A LV with an inferior wall defect was also simulated in both phantoms over the same range of positions. Real camera data were acquired on a Discovery NM530c camera (GE Healthcare, Haifa, Israel) for five min in list-mode using an anthropomorphic phantom (DataSpectrum, Durham, NC) with 100 MBq of Tc-99m in the LV. Images were taken over the same range of positions as the simulations and were compared based on the summed perfusion score (SPS), defect width, and apparent defect uptake for each position. Results: Point sources in the water phantom showed absolute changes in attenuation of ≤8% over the range of positions and relative changes of ≤5% compared to the apex. In the anthropomorphic computer simulations, absolute change increased to 20%. The changes in relative attenuation caused a change in SPS of <1.5 for the water phantom but up to 4.2 in the anthropomorphic phantom. Changes were larger for axial than for transverse translations. These results were supported by SPS changes of up to six seen in the physical anthropomorphic phantom for axial translations. Defect width was also seen to significantly increase. The

  14. Transient attenuation in optical fibers

    International Nuclear Information System (INIS)

    Hopkins, A.A.; Kelly, R.E.; Looney, L.D.; Lyons, P.B.

    1984-01-01

    Low and high energy pulsed electron beams were used to generate radiation-induced transient attenuation in high-OH, Suprasil core, PCS fibers, demonstrating the energy dependence of the radiation damage and recovery mechanisms. A radiation resistant low-OH fiber was studied and its performance contrasted to that of high-OH materials. Several fibers with differing core compositions were also studied

  15. A Generalized Correction for Attenuation.

    Science.gov (United States)

    Petersen, Anne C.; Bock, R. Darrell

    Use of the usual bivariate correction for attenuation with more than two variables presents two statistical problems. This pairwise method may produce a covariance matrix which is not at least positive semi-definite, and the bivariate procedure does not consider the possible influences of correlated errors among the variables. The method described…

  16. Compact plasmonic variable optical attenuator

    DEFF Research Database (Denmark)

    Leosson, Kristjan; Rosenzveig, Tiberiu; Hermannsson, Pétur Gordon

    2008-01-01

    We demonstrate plasmonic nanowire-based thermo-optic variable optical attenuators operating in the 1525-1625 nm wavelength range. The devices have a footprint as low as 1 mm, extinction ratio exceeding 40 dB, driving voltage below 3 V, and full modulation bandwidth of 1 kHz. The polarization...

  17. Attenuation of Vrancea events revisited

    International Nuclear Information System (INIS)

    Radulian, M.; Popa, M.; Grecu, B.; Panza, G.F.

    2003-11-01

    New aspects of the frequency-dependent attenuation of the seismic waves traveling from Vrancea subcrustal sources toward NW (Transylvanian Basin) and SE (Romanian Plain) are evidenced by the recent experimental data made available by the CALIXTO'99 tomography experiment. The observations validate the previous theoretical computations performed for the assessment, by means of a deterministic approach, of the seismic hazard in Romania. They reveal an essential aspect of the seismic ground motion attenuation, that has important implications on the probabilistic assessment of seismic hazard from Vrancea intermediate-depth earthquakes. The attenuation toward NW is shown to be a much stronger frequency-dependent effect than the attenuation toward SE and the seismic hazard computed by the deterministic approach fits satisfactorily well the observed ground motion distribution in the low-frequency band (< 1 Hz). The apparent contradiction with the historically-based intensity maps arises mainly from a systematic difference in the vulnerability (buildings eigenperiod) of the buildings in the intra- and extra-Carpathians regions. (author)

  18. Physics of the tropospheric radiopropagation

    International Nuclear Information System (INIS)

    Ajayi, G.O.

    1989-02-01

    The physics of the tropospheric radiopropagation is presented considering the atmospheric radio refractive index and taking into account the influence of precipitation and the attenuation due to the atmospheric gases. 35 refs, 20 figs, 3 tabs

  19. Factors influencing radon attenuation by tailing covers

    International Nuclear Information System (INIS)

    Silker, W.B.; Rogers, V.C.

    1981-07-01

    The US NRC, in its Generic Environmental Impact Statement on uranium milling has specified that the radon flux escaping a uranium mill tailings pile will be reduced to pCi/m 2 s by application of covering layers of soils and clays. These covers present a radon diffusion barrier, which sufficiently increases the time required for radon passage from the tailings to the atmosphere to allow for decay of 222 Rn within the cover. The depth of cover necessary to reduce the escaping radon flux to the prescribed level is to be determined by calculation, and requires precise knowledge of the radon diffusion coefficient in the covering media. A Radon Attenuation Test Facility was developed to determine rates of radon diffusion through candidate cover materials. This paper describes this facility and its application for determining the influence of physical properties of the soil column on the radon diffusion coefficient

  20. An Analytical-empirical Calculation of Linear Attenuation Coefficient of Megavoltage Photon Beams.

    Science.gov (United States)

    Seif, F; Tahmasebi-Birgani, M J; Bayatiani, M R

    2017-09-01

    In this study, a method for linear attenuation coefficient calculation was introduced. Linear attenuation coefficient was calculated with a new method that base on the physics of interaction of photon with matter, mathematical calculation and x-ray spectrum consideration. The calculation was done for Cerrobend as a common radiotherapy modifier and Mercury. The values of calculated linear attenuation coefficient with this new method are in acceptable range. Also, the linear attenuation coefficient decreases slightly as the thickness of attenuating filter (Cerrobend or mercury) increased, so the procedure of linear attenuation coefficient variation is in agreement with other documents. The results showed that the attenuation ability of mercury was about 1.44 times more than Cerrobend. The method that was introduced in this study for linear attenuation coefficient calculation is general enough to treat beam modifiers with any shape or material by using the same formalism; however, calculating was made only for mercury and Cerrobend attenuator. On the other hand, it seems that this method is suitable for high energy shields or protector designing.

  1. ENHANCEMENTS TO NATURAL ATTENUATION: SELECTED CASE STUDIES

    Energy Technology Data Exchange (ETDEWEB)

    Vangelas, K; W. H. Albright, W; E. S. Becvar, E; C. H. Benson, C; T. O. Early, T; E. Hood, E; P. M. Jardine, P; M. Lorah, M; E. Majche, E; D. Major, D; W. J. Waugh, W; G. Wein, G; O. R. West, O

    2007-05-15

    In 2003 the US Department of Energy (DOE) embarked on a project to explore an innovative approach to remediation of subsurface contaminant plumes that focused on introducing mechanisms for augmenting natural attenuation to achieve site closure. Termed enhanced attenuation (EA), this approach has drawn its inspiration from the concept of monitored natural attenuation (MNA).

  2. Effects of attenuation map accuracy on attenuation-corrected micro-SPECT images

    NARCIS (Netherlands)

    Wu, C.; Gratama van Andel, H.A.; Laverman, P.; Boerman, O.C.; Beekman, F.J.

    2013-01-01

    Background In single-photon emission computed tomography (SPECT), attenuation of photon flux in tissue affects quantitative accuracy of reconstructed images. Attenuation maps derived from X-ray computed tomography (CT) can be employed for attenuation correction. The attenuation coefficients as well

  3. Mechanisms of geometrical seismic attenuation

    Directory of Open Access Journals (Sweden)

    Igor B. Morozov

    2011-07-01

    Full Text Available In several recent reports, we have explained the frequency dependence of the apparent seismic quality-factor (Q observed in many studies according to the effects of geometrical attenuation, which was defined as the zero-frequency limit of the temporal attenuation coefficient. In particular, geometrical attenuation was found to be positive for most waves traveling within the lithosphere. Here, we present three theoretical models that illustrate the origin of this geometrical attenuation, and we investigate the causes of its preferential positive values. In addition, we discuss the physical basis and limitations of both the conventional and new attenuation models. For waves in media with slowly varying properties, geometrical attenuation is caused by variations in the wavefront curvature, which can be both positive (for defocusing and negative (for focusing. In media with velocity/density contrasts, incoherent reflectivity leads to geometrical-attenuation coefficients which are proportional to the mean squared reflectivity and are always positive. For «coherent» reflectivity, the geometrical attenuation is approximately zero, and the attenuation process can be described according to the concept of «scattering Q». However, the true meaning of this parameter is in describing the mean reflectivity within the medium, and not that of the traditional resonator quality factor known in mechanics. The general conclusion from these models is that non-zero and often positive levels of geometrical attenuation are common in realistic, heterogeneous media, both observationally and theoretically. When transformed into the conventional Q-factor form, this positive geometrical attenuation leads to Q values that quickly increase with frequency. These predictions show that the positive frequency-dependent Q observed in many datasets might represent artifacts of the transformations of the attenuation coefficients into Q.

  1. Attenuation characteristics of gypsum wallboard

    International Nuclear Information System (INIS)

    Christensen, Ralph C.; Sayeg, Joseph

    1978-01-01

    Increased cost of lead is promoting enhanced usage of common building materials for shielding in diagnostic medical and dental facilities where only a few half value layers (HVLs) are needed. We have measured attenuation of x-rays in gypsum wallboard as a function of kVp, filtration, and wallboard thickness. Our findings, obtained using a Victoreen 555 with an 0.1 DAS probe in poor geometry, are in agreement with the sparse data in the literature (Gross and McCullough (1977), Radiology 122: 825. Moos et al. (1961), Oral Surgery, Oral Medicine, and Oral Pathology 14: 569) but extend to thicker wall configurations and different kVp and filtration parameters. We conclude that gypsum wallboard as sole shielding material should be used with great caution. These findings are of value in maximizing the benefit/cost ratio for diagnostic shielding, and strengthen the conviction that, where used for shielding purposes, common building materials must be installed carefully and HVL-depth dependence considered thoroughly. (author)

  2. Natural attenuation of hydrocarbon polluted soils in Mexico

    International Nuclear Information System (INIS)

    Fernandez-Linares, L.; Rojas-Avelizapa, N.; Roldan-Carrillo, T.; Islas-Ramirez, M.

    2009-01-01

    Crude oil and hydrocarbon by-proudcts are the most common pollutants in Mexico. In the last years, the two terms, contamination and remediation have being re-defined; also, based on both the scientific advancement and the human risk, the sustentability of remediation technologies and the definition of cleaning levels has been taking place. In this context, the Natural Attenuation of soils is a viable and low cost remediation choice, defined as the degradation of organic compounds without artificial stimulation, through microbial activity including physical processes, such as volatilization, dilution, sorption, and hydraulic dispersion. (Author)

  3. Electron attenuation anisotropy at crystal surfaces from LEED

    Czech Academy of Sciences Publication Activity Database

    Romanyuk, Olexandr; Bartoš, Igor

    2009-01-01

    Roč. 603, č. 17 (2009), s. 2789-2792 ISSN 0039-6028 R&D Projects: GA ČR GA202/07/0601; GA AV ČR IAA100100628 Institutional research plan: CEZ:AV0Z10100521 Keywords : electron attenuation length, low energy electron diffraction, photoelectron diffraction, electron–solid scattering and transmission, copper * low energy electron diffraction * photoelectron diffraction * electron–solid scattering and transmission * copper Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.798, year: 2009 http://dx.doi.org/10.1016/j.susc.2009.07.024

  4. Light attenuation in estuarine mangrove lakes

    Science.gov (United States)

    Frankovich, Thomas A.; Rudnick, David T.; Fourqurean, James W.

    2017-01-01

    Submerged aquatic vegetation (SAV) cover has declined in brackish lakes in the southern Everglades characterized by low water transparencies, emphasizing the need to evaluate the suitability of the aquatic medium for SAV growth and to identify the light attenuating components that contribute most to light attenuation. Underwater attenuation of downwards irradiance of photosynthetically active radiation (PAR) was determined over a three year period at 42 sites in shallow (freshwater flow into these areas may dilute CDOM concentrations and improve the salinity and light climate for SAV communities.

  5. Perturbed effects at radiation physics

    International Nuclear Information System (INIS)

    Külahcı, Fatih; Şen, Zekâi

    2013-01-01

    Perturbation methodology is applied in order to assess the linear attenuation coefficient, mass attenuation coefficient and cross-section behavior with random components in the basic variables such as the radiation amounts frequently used in the radiation physics and chemistry. Additionally, layer attenuation coefficient (LAC) and perturbed LAC (PLAC) are proposed for different contact materials. Perturbation methodology provides opportunity to obtain results with random deviations from the average behavior of each variable that enters the whole mathematical expression. The basic photon intensity variation expression as the inverse exponential power law (as Beer–Lambert's law) is adopted for perturbation method exposition. Perturbed results are presented not only in terms of the mean but additionally the standard deviation and the correlation coefficients. Such perturbation expressions provide one to assess small random variability in basic variables. - Highlights: • Perturbation methodology is applied to Radiation Physics. • Layer attenuation coefficient (LAC) and perturbed LAC are proposed for contact materials. • Perturbed linear attenuation coefficient is proposed. • Perturbed mass attenuation coefficient (PMAC) is proposed. • Perturbed cross-section is proposed

  6. Seismic attenuation system for a nuclear reactor

    Energy Technology Data Exchange (ETDEWEB)

    Liszkai, Tamas; Cadell, Seth

    2018-01-30

    A system for attenuating seismic forces includes a reactor pressure vessel containing nuclear fuel and a containment vessel that houses the reactor pressure vessel. Both the reactor pressure vessel and the containment vessel include a bottom head. Additionally, the system includes a base support to contact a support surface on which the containment vessel is positioned in a substantially vertical orientation. An attenuation device is located between the bottom head of the reactor pressure vessel and the bottom head of the containment vessel. Seismic forces that travel from the base support to the reactor pressure vessel via the containment vessel are attenuated by the attenuation device in a direction that is substantially lateral to the vertical orientation of the containment vessel.

  7. Attenuation measurements in solutions of some carbohydrates

    International Nuclear Information System (INIS)

    Gagandeep; Singh, K.; Lark, B.S.; Sahota, H.S.

    2000-01-01

    The linear attenuation coefficients in aqueous solutions of three carbohydrates, glucose (C 6 H 12 O 6 ), maltose monohydrate (C 12 H 22 O 11 ·H 2 O), and sucrose (C 12 H 22 O 11 ), were determined at 81, 356, 511, 662, 1,173, and 1,332 keV by the gamma-ray transmission method in a good geometry setup. From the precisely measured densities of these solutions, mass attenuation coefficients were then obtained that varied systematically with the corresponding changes in the concentrations (g/cm 3 ) of these solutions. The experimental results were used in terms of effective atomic numbers and electron densities. A comparison between experimental and theoretical values of attenuation coefficients has proven that the study has a potential application for the determination of attenuation coefficients of solid solutes from their solutions without obtaining them in pure crystalline form

  8. Attenuation Measurements in Solutions of Some Carbohydrates

    International Nuclear Information System (INIS)

    Gagandeep; Singh, Kulwant; Lark, B.S.; Sahota, H.S.

    2000-01-01

    The linear attenuation coefficients in aqueous solutions of three carbohydrates, glucose (C 6 H 12 O 6 ), maltose monohydrate (C 12 H 22 O 11 .H 2 O), and sucrose (C 12 H 22 O 11 ), were determined at 81, 356, 511, 662, 1173, and 1332 keV by the gamma-ray transmission method in a good geometry setup. From the precisely measured densities of these solutions, mass attenuation coefficients were then obtained that varied systematically with the corresponding changes in the concentrations (g/cm 3 ) of these solutions. The experimental results were used in terms of effective atomic numbers and electron densities. A comparison between experimental and theoretical values of attenuation coefficients has proven that the study has a potential application for the determination of attenuation coefficients of solid solutes from their solutions without obtaining them in pure crystalline form

  9. Radiation-attenuated vaccine for lungworm disease

    International Nuclear Information System (INIS)

    Singh, C.M.

    1977-01-01

    The work done at the Indian Veternary Research Institute, Izatnagar, on the development of a vaccine for lungworm diseases is reported. Research work done includes: (1) studies on the epidemiology and the incidence of the lungworm infections, (ii) studies on the radiation-attenuated lungworm Dictyocaulus filaria vaccine, (iii) studies on other parasites using ionizing radiation, (iv) incidence of lungworm infection in sheep in Jammu and Kashmir State, (v) suitable dose of gamma radiation for attenuation, (vi) laboratory studies with radiation-attenuated D. filaria vaccine, (vii) serology of D. filaria infection, (viii) field trials with the radiation-attenuated vaccine, (ix) immune response of previously exposed lambs to vaccination, (x) comparative susceptibility of sheep and goats to infection with D. filaria, (xi) quantitative studies of D. filaria in lambs and (xii) production and supply of lungworm vaccine. (A.K.)

  10. Post-Retrieval Extinction Attenuates Cocaine Memories

    OpenAIRE

    Sartor, Gregory C; Aston-Jones, Gary

    2013-01-01

    Recent studies have shown that post-retrieval extinction training attenuates fear and reward-related memories in both humans and rodents. This noninvasive, behavioral approach has the potential to be used in clinical settings to treat maladaptive memories that underlie several psychiatric disorders, including drug addiction. However, few studies to date have used a post-retrieval extinction approach to attenuate addiction-related memories. In the current study, we attempted to disrupt cocaine...

  11. Electron Effective-Attenuation-Length Database

    Science.gov (United States)

    SRD 82 NIST Electron Effective-Attenuation-Length Database (PC database, no charge)   This database provides values of electron effective attenuation lengths (EALs) in solid elements and compounds at selected electron energies between 50 eV and 2,000 eV. The database was designed mainly to provide EALs (to account for effects of elastic-eletron scattering) for applications in surface analysis by Auger-electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS).

  12. Investigation of photon attenuation coefficients for marble

    International Nuclear Information System (INIS)

    Basyigit, C; Akkurt, I; Kilincarslan, S; Akkurt, A

    2005-01-01

    The total linear attenuation coefficients μ (cm -1 ) have been obtained using the XCOM program at photon energies of 1 keV to 1 GeV for six different natural marbles produced in different places in Turkey. The individual contribution of photon interaction processes to the total linear attenuation coefficients for marble has been investigated. The calculated results were also compared with the measurements. The results obtained for marble were also compared with concrete. (note)

  13. Seismic Full Waveform Modeling & Imaging in Attenuating Media

    Science.gov (United States)

    Guo, Peng

    Seismic attenuation strongly affects seismic waveforms by amplitude loss and velocity dispersion. Without proper inclusion of Q parameters, errors can be introduced for seismic full waveform modeling and imaging. Three different (Carcione's, Robertsson's, and the generalized Robertsson's) isotropic viscoelastic wave equations based on the generalized standard linear solid (GSLS) are evaluated. The second-order displacement equations are derived, and used to demonstrate that, with the same stress relaxation times, these viscoelastic formulations are equivalent. By introducing separate memory variables for P and S relaxation functions, Robertsson's formulation is generalized to allow different P and S wave stress relaxation times, which improves the physical consistency of the Qp and Qs modelled in the seismograms.The three formulations have comparable computational cost. 3D seismic finite-difference forward modeling is applied to anisotropic viscoelastic media. The viscoelastic T-matrix (a dynamic effective medium theory) relates frequency-dependent anisotropic attenuation and velocity to reservoir properties in fractured HTI media, based on the meso-scale fluid flow attenuation mechanism. The seismic signatures resulting from changing viscoelastic reservoir properties are easily visible. Analysis of 3D viscoelastic seismograms suggests that anisotropic attenuation is a potential tool for reservoir characterization. To compensate the Q effects during reverse-time migration (RTM) in viscoacoustic and viscoelastic media, amplitudes need to be compensated during wave propagation; the propagation velocity of the Q-compensated wavefield needs to be the same as in the attenuating wavefield, to restore the phase information. Both amplitude and phase can be compensated when the velocity dispersion and the amplitude loss are decoupled. For wave equations based on the GSLS, because Q effects are coupled in the memory variables, Q-compensated wavefield propagates faster than

  14. Attenuation of concentration fluctuations of water vapor and other trace gases in turbulent tube flow

    Directory of Open Access Journals (Sweden)

    W. J. Massman

    2008-10-01

    Full Text Available Recent studies with closed-path eddy covariance (EC systems have indicated that the attenuation of fluctuations of water vapor concentration is dependent upon ambient relative humidity, presumably due to sorption/desorption of water molecules at the interior surface of the tube. Previous studies of EC-related tube attenuation effects have either not considered this issue at all or have only examined it superficially. Nonetheless, the attenuation of water vapor fluctuations is clearly much greater than might be expected from a passive tracer in turbulent tube flow. This study reexamines the turbulent tube flow issue for both passive and sorbing tracers with the intent of developing a physically-based semi-empirical model that describes the attenuation associated with water vapor fluctuations. Toward this end, we develop a new model of tube flow dynamics (radial profiles of the turbulent diffusivity and tube airstream velocity. We compare our new passive-tracer formulation with previous formulations in a systematic and unified way in order to assess how sensitive the passive-tracer results depend on fundamental modeling assumptions. We extend the passive tracer model to the vapor sorption/desorption case by formulating the model's wall boundary condition in terms of a physically-based semi-empirical model of the sorption/desorption vapor fluxes. Finally we synthesize all modeling and observational results into a single analytical expression that captures the effects of the mean ambient humidity and tube flow (Reynolds number on tube attenuation.

  15. Lg Attenuation Modeling in the Middle East

    Science.gov (United States)

    Pasyanos, M. E.; Matzel, E. M.; Walter, W. R.; Rodgers, A. J.

    2008-12-01

    We present a broadband tomographic model of Lg attenuation in the Middle East derived from source- and site-corrected amplitudes. The study region spans from Turkey through the Arabian Peninsula and Iran to Pakistan, Afghanistan, and northwest India. Absolute amplitude measurements are made on hand-selected and carefully windowed seismograms for tens of stations and thousands of crustal earthquakes resulting in excellent coverage of the region. We have modified the standard attenuation tomography technique to more explicitly define the earthquake source expression in terms of the seismic moment. This facilitates the use of the model to predict the expected amplitudes of new events, an important consideration for earthquake hazard or explosion monitoring applications. We will discuss the updated method and implications of this parameterization. A conjugate gradient method is used to tomographically invert the amplitude dataset of over 8000 paths. We solve for Q variation, as well as site and source terms, for a wide range of frequencies ranging from 0.5 -- 10 Hz. The attenuation results have a strong correlation to tectonics. Shields have low attenuation, while tectonic regions have high attenuation, with the highest attenuation at 1 Hz found in eastern Turkey. The results also compare favorably to other studies in the region made using Lg propagation efficiency, Lg/Pg amplitude ratios and two-station methods. We tomographically invert the amplitude measurements for each frequency independently. In doing so, it appears the frequency-dependence of attenuation is not compatible with the power law representation of Q(f). This research was performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract number DE-AC52-07NA27344. This is LLNL contribution LLNL-ABS-406761.

  16. Maximum likelihood estimation of the attenuated ultrasound pulse

    DEFF Research Database (Denmark)

    Rasmussen, Klaus Bolding

    1994-01-01

    The attenuated ultrasound pulse is divided into two parts: a stationary basic pulse and a nonstationary attenuation pulse. A standard ARMA model is used for the basic pulse, and a nonstandard ARMA model is derived for the attenuation pulse. The maximum likelihood estimator of the attenuated...

  17. Fat Attenuation at CT in Anorexia Nervosa

    Science.gov (United States)

    Gill, Corey M.; Torriani, Martin; Murphy, Rachel; Harris, Tamara B.; Miller, Karen K.; Klibanski, Anne

    2016-01-01

    Purpose To investigate the composition, cross-sectional area (CSA), and hormonal correlates of different fat depots in women with anorexia nervosa (AN) and control subjects with normal weights to find out whether patients with AN have lower fat CSA but higher attenuation than did control subjects and whether these changes may be mediated by gonadal steroids, cortisol, and thyroid hormones. Materials and Methods This study was institutional review board approved and HIPAA compliant. Written informed consent was obtained. Forty premenopausal women with AN and 40 normal-weight women of comparable age (mean age ± standard deviation, 26 years ± 5) were studied. All individuals underwent computed tomography of the abdomen and thigh with a calibration phantom. Abdominal subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), thigh SAT, and thigh intermuscular adipose tissue CSA and attenuation were quantified. Serum estradiol, thyroid hormones, and urinary free cortisol levels were assessed. Variables were compared by using analysis of variance. Associations were examined by using linear regression analysis. Results Women with AN had higher fat attenuation than did control subjects (−100.1 to −46.7 HU vs −117.6 to −61.8 HU, P < .0001), despite lower fat CSA (2.0–62.8 cm2 vs 5.5–185.9 cm2, P < .0001). VAT attenuation but not CSA was inversely associated with lowest prior lifetime body mass index in AN (r = −0.71, P = .006). Serum estradiol levels were inversely associated with fat attenuation (r = −0.34 to −0.61, P = .03 to <.0001) and were positively associated with fat CSA of all compartments (r = 0.42–0.64, P = .007 to <.0001). Thyroxine levels and urinary free cortisol levels were positively associated with thigh SAT attenuation (r = 0.64 [P = .006] and r = 0.68 [P = .0004], respectively) and were inversely associated with abdominal SAT and VAT CSA (r = −0.44 to −0.58, P = .04 to .02). Conclusion Women with AN have differences in fat

  18. Elastic wave attenuation in rocks containing fluids

    International Nuclear Information System (INIS)

    Berryman, J.G.

    1986-01-01

    The low-frequency limit of Biot's theory of fluid-saturated porous media predicts that the coefficients for viscous attenuation of shear waves and of the fast compressional wave are proportional to the fluid permeability. Although the observed attenuation is generally in qualitative agreement with the theory, the magnitude of the observed attenuation coefficient in rocks is often more than an order of magnitude higher than expected. This apparent dilemma can be resolved without invoking other attenuation mechanisms if the intrinsic permeability of the rock is inhomogeneous and varies widely in magnitude. A simple calculation of the overall behavior of a layered porous material using local-flow Biot theory shows that the effective permeability for attenuation is the mean of the constituent permeabilities while the effective permeability for fluid flow is the harmonic mean. When the range of variation in the local permeability is one or more orders of magnitude, this difference in averaging method can easily explain some of the observed discrepancies

  19. Ultrasonic attenuation in the superconducting and intermediate states of pure and doped type I superconductors

    International Nuclear Information System (INIS)

    Chaudhuri, K.D.; Singh, R.

    1982-01-01

    The attenuation of longitudinal ultrasonic waves has been measured in single crystals of indium (99.999%), indium doped with 0.003 at % of tin, and indium doped with 0.002 at % of bismuth in the intermediate and superconducting states over the frequency range 10--30 MHz. For the bismuth-doped indium specimen, measurements were taken for three different physical states, i.e., for three different dislocation densities, and for the indium and the tin-doped indium specimens, measurements were for one-physical state. For a particular measurement, the same physical state was maintained both in the intermediate and superconducting states. A temperature-dependent oscillatory behavior of the ultrasonic attenuation was observed in the intermediate state in all the three specimens, but in the superconducting state the oscillatory behavior was observed only in the bismuth-doped specimen. Two phases have been identified in the superconducting layers of the intermediate state and there is only one phase in the superconducting state of the bismuth-doped sample. The origin of the two phases in the intermediate state and that of the single phase in the superconducting state of the bismuth-doped sample are discussed. A qualitative explanation is presented for the occurrence of oscillatory attenuation in the intermediate state irrespective of the nature of the dopant and the selective occurrence of oscillatory attenuation in the superconducting state due to the nature of the dopant

  20. Attenuation of the gamma rays in tissues

    International Nuclear Information System (INIS)

    Arcos P, A.; Rodriguez N, S.; Pinedo S, A.; Amador V, P.; Chacon R, A.; Vega C, H.R.

    2005-01-01

    The mass and lineal attenuation coefficient and of hepatic tissue, muscular, osseous and of brain before gamma rays of 10 -3 to 10 5 MeV were calculated. For the case of the osseous tissue the calculation was made for the cartilage, the cortical tissue and the bone marrow. During the calculations the elementary composition of the tissues of human origin was used. The calculations include by separate the Photoelectric effect, the Compton scattering and the Pair production, as well as the total. For to establish a comparison with the attenuation capacities, the coefficients of the water, the aluminum and the lead also were calculated. The study was complemented measuring the attenuation coefficient of hepatic tissue of bovine before gamma rays of 0.662 MeV of a source of 137 Cs. The measurement was made through of an experiment of photons transmission through samples frozen of hepatic tissue and with a Geiger-Mueller detector. (Author)

  1. Electromagnetic Wave Attenuation in Atmospheric Pressure Plasma

    International Nuclear Information System (INIS)

    Zhang Shu; Hu Xiwei; Liu Minghai; Luo Fang; Feng Zelong

    2007-01-01

    When an electromagnetic (EM) wave propagates in an atmospheric pressure plasma (APP) layer, its attenuation depends on the APP parameters such as the layer width, the electron density and its profile and collision frequency between electrons and neutrals. This paper proposes that a combined parameter-the product of the line average electron density n-bar and width d of the APP layer (i.e., the total number of electrons in a unit volume along the wave propagation path) can play a more explicit and decisive role in the wave attenuation than any of the above individual parameters does. The attenuation of the EM wave via the product of n-bar and d with various collision frequencies between electrons and neutrals is presented

  2. Physics for radiation protection

    CERN Document Server

    Martin, James E

    2013-01-01

    A much-needed working resource for health physicists and other radiation protection professionals, this volume presents clear, thorough, up-to-date explanations of the basic physics necessary to address real-world problems in radiation protection. Designed for readers with limited as well as basic science backgrounds, Physics for Radiation Protection emphasizes applied concepts and carefully illustrates all topics through examples as well as practice problems. Physics for Radiation Protection draws substantially on current resource data available for health physics use, providing decay schemes and emission energies for approximately 100 of the most common radionuclides encountered by practitioners. Excerpts of the Chart of the Nuclides, activation cross sections, fission yields, fission-product chains, photon attenuation coefficients, and nuclear masses are also provided.

  3. 3-D seismic velocity and attenuation structures in the geothermal field

    Energy Technology Data Exchange (ETDEWEB)

    Nugraha, Andri Dian [Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Institute of Technology Bandung, Jalan Ganesha No. 10 Bandung, 40132 (Indonesia); Syahputra, Ahmad [Geophyisical Engineering, Faculty of Mining and Petroleum Engineering, Institute of Technology Bandung, Jalan Ganesha No. 10 Bandung, 40132 (Indonesia); Fatkhan,; Sule, Rachmat [Applied Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Institute of Technology Bandung, Jalan Ganesha No. 10 Bandung, 40132 (Indonesia)

    2013-09-09

    We conducted delay time tomography to determine 3-D seismic velocity structures (Vp, Vs, and Vp/Vs ratio) using micro-seismic events in the geothermal field. The P-and S-wave arrival times of these micro-seismic events have been used as input for the tomographic inversion. Our preliminary seismic velocity results show that the subsurface condition of geothermal field can be fairly delineated the characteristic of reservoir. We then extended our understanding of the subsurface physical properties through determining of attenuation structures (Qp, Qs, and Qs/Qp ratio) using micro-seismic waveform. We combined seismic velocities and attenuation structures to get much better interpretation of the reservoir characteristic. Our preliminary attanuation structures results show reservoir characterization can be more clearly by using the 3-D attenuation model of Qp, Qs, and Qs/Qp ratio combined with 3-D seismic velocity model of Vp, Vs, and Vp/Vs ratio.

  4. Monitored Natural Attenuation of ino9rganic Contaminants Treatability Study Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Crapse, K

    2004-05-19

    The identification and quantification of key natural attenuation processes for inorganic contaminants at D-Area is detailed herein. Two overarching goals of this evaluation of monitored natural attenuation (MNA) as a remediation strategy were (1) to better define the availability of inorganic contaminants as potential sources for transport to groundwater and uptake by environmental receptors and (2) to understand the site-specific mechanisms controlling attenuation of these inorganic contaminants through tandem geochemical and biological characterization. Data collected in this study provides input for more appropriate site groundwater transport models. Significant natural attenuation is occurring at D-Area as evidenced by relatively low aqueous concentrations of constituents of concern (COCs) (Be, Ni, U, and As) at all locations characterized and the decrease in groundwater concentrations with increasing distance from the source. The observed magnitude of decrease in groundwater concentrations of COCs with distance from the D-Area Coal Pile Runoff Basin (DCPRB) could not be accounted for by the modeled physical attenuation processes of dilution/dispersion. This additional attenuation, i.e., the observed difference between the groundwater concentrations of COCs and the modeled physical attenuation, is due to biogeochemical processes occurring at the D-Area. In tandem geochemical and microbiological characterization studies designed to evaluate the mechanisms contributing to natural attenuation, pH was the single parameter found to be most predictive of contaminant attenuation. The increasing pH with distance from the source is likely responsible for increased sorption of COCs to soil surfaces within the aquifer at D-Area. Importantly, because the sediments appear to have a high buffering capacity, the acid emanating from the DCPRB has been neutralized by the soil, and these conditions have led to large Kd values at the site. Two major types of soils are present at

  5. Mechanical spectroscopy, internal friction and ultrasonic attenuation: Collection of works

    International Nuclear Information System (INIS)

    Magalas, L.B.

    2009-01-01

    An extensive collection of recommended books and proceedings from numerous conferences on internal friction, mechanical spectroscopy, and ultrasonic attenuation is provided. Reflecting the complicated history of the 20th century, books published in English and in Russian are presented in two separate sections. International and national conferences organized in various countries are listed. Supplementary lists referring to conferences held in the People's Republic of China, Poland, Russia, the Soviet Union, and Ukraine are also provided. The interesting evolution of mechanical spectroscopy from internal friction and ultrasonic attenuation in solids is clearly demonstrated, and a choice list of retrospective papers illustrates the evolution of the field. A brief review of mechanical spectroscopy, therefore, is included. Numerous research areas investigated by internal friction and mechanical spectroscopy are addressed, including point defect relaxations, electronic and phonon relaxations, dislocation relaxations, grain boundary relaxations, domain induced relaxations (magnetic, ferroelectric), magnetomechanical relaxations, phase transformations, glass transitions, interface effects as well as a wide array of applications specific to physics and materials science. For many years now, there has been a definite need to provide a thorough list of references that might cover major national conferences and books published in English and other languages. This work strives to achieve this goal.

  6. Natural attenuation of diesel fuel in heavy clay soil

    International Nuclear Information System (INIS)

    Berry, K.A.T.; Burton, D.L.

    1997-01-01

    The application of bioremediation techniques on heavy clay soils contaminated with diesel fuels was studied. Earlier studies suggested that in-situ bioreclamation was only effective on permeable soils such as medium- to coarse-textured sandy or loamy soils. It was assumed that heavy clay soils such as those found in the Red River Valley in Southern Manitoba had physical and chemical properties that would limit the usefulness of natural attenuation. In this study, the disappearance and the natural attenuation of diesel fuel added to soil at a rate of 5000 mg/kg soil in tilled and untilled heavy clay soil was monitored. Three methods of analysis were used: (1) oil and grease content, (2) extractable organics, and (3) the Millipore EnviroGard ELISA method for petroleum hydrocarbons. Effects of the contamination on the soil microbial population were measured using surface CO 2 flux measurements and microbial biomass carbon analysis. Soil moisture contents at all sample times were between 44 and 49 per cent. Soil temperature was also monitored. All three analytical methods used in the study showed the near-complete disappearance of detectable diesel fuel hydrocarbons from the soil after 30 days with half-lives ranging from 11 to 26 days. The advantages and limitations of the ELISA kit were described. No hydrocarbons were detected in the groundwater sample. 45 refs., 7 tabs., 2 figs

  7. Attenuation correction for the large non-human primate brain imaging using microPET

    International Nuclear Information System (INIS)

    Naidoo-Variawa, S; Lehnert, W; Kassiou, M; Banati, R; Meikle, S R

    2010-01-01

    Assessment of the biodistribution and pharmacokinetics of radiopharmaceuticals in vivo is often performed on animal models of human disease prior to their use in humans. The baboon brain is physiologically and neuro-anatomically similar to the human brain and is therefore a suitable model for evaluating novel CNS radioligands. We previously demonstrated the feasibility of performing baboon brain imaging on a dedicated small animal PET scanner provided that the data are accurately corrected for degrading physical effects such as photon attenuation in the body. In this study, we investigated factors affecting the accuracy and reliability of alternative attenuation correction strategies when imaging the brain of a large non-human primate (papio hamadryas) using the microPET Focus 220 animal scanner. For measured attenuation correction, the best bias versus noise performance was achieved using a 57 Co transmission point source with a 4% energy window. The optimal energy window for a 68 Ge transmission source operating in singles acquisition mode was 20%, independent of the source strength, providing bias-noise performance almost as good as for 57 Co. For both transmission sources, doubling the acquisition time had minimal impact on the bias-noise trade-off for corrected emission images, despite observable improvements in reconstructed attenuation values. In a [ 18 F]FDG brain scan of a female baboon, both measured attenuation correction strategies achieved good results and similar SNR, while segmented attenuation correction (based on uncorrected emission images) resulted in appreciable regional bias in deep grey matter structures and the skull. We conclude that measured attenuation correction using a single pass 57 Co (4% energy window) or 68 Ge (20% window) transmission scan achieves an excellent trade-off between bias and propagation of noise when imaging the large non-human primate brain with a microPET scanner.

  8. GPR measurements of attenuation in concrete

    Energy Technology Data Exchange (ETDEWEB)

    Eisenmann, David, E-mail: djeisen@cnde.iastate.edu; Margetan, Frank J., E-mail: djeisen@cnde.iastate.edu; Pavel, Brittney, E-mail: djeisen@cnde.iastate.edu [Center for Nondestructive Evaluation, Iowa State University, 1915 Scholl Road, Ames, IA 50011-3042 (United States)

    2015-03-31

    Ground-penetrating radar (GPR) signals from concrete structures are affected by several phenomenon, including: (1) transmission and reflection coefficients at interfaces; (2) the radiation patterns of the antenna(s) being used; and (3) the material properties of concrete and any embedded objects. In this paper we investigate different schemes for determining the electromagnetic (EM) attenuation of concrete from measured signals obtained using commercially-available GPR equipment. We adapt procedures commonly used in ultrasonic inspections where one compares the relative strengths of two or more signals having different travel paths through the material of interest. After correcting for beam spread (i.e., diffraction), interface phenomena, and equipment amplification settings, any remaining signal differences are assumed to be due to attenuation thus allowing the attenuation coefficient (say, in dB of loss per inch of travel) to be estimated. We begin with a brief overview of our approach, and then discuss how diffraction corrections were determined for our two 1.6 GHz GPR antennas. We then present results of attenuation measurements for two types of concrete using both pulse/echo and pitch/catch measurement setups.

  9. Mirtazapine attenuates cocaine seeking in rats.

    Science.gov (United States)

    Barbosa-Méndez, Susana; Leff, Phillipe; Arías-Caballero, Adriana; Hernández-Miramontes, Ricardo; Heinze, Gerardo; Salazar-Juárez, Alberto

    2017-09-01

    Relapse to cocaine use is a major problem in the clinical treatment of cocaine addiction. Antidepressants have been studied for their therapeutic potential to treat cocaine use disorder. Research has suggested that antidepressants attenuate both drug craving and the re-acquisition of drug-seeking and drug-taking behaviors. This study examined the efficacy of mirtazapine, an antidepressant/anxiolytic, in decreasing cocaine seeking in rats. We used the cocaine self-administration paradigm to assess the effects of mirtazapine on rats trained to self-administer cocaine or food under a fixed-ratio schedule. Mirtazapine (30 mg/kg, i.p.) was administered during extinction. Mirtazapine significantly attenuated non-reinforced lever-press responses during extinction. Moreover, the mirtazapine dosed for 30 days during extinction produced sustained attenuation of lever-press responses during re-acquisition of cocaine self-administration, without changing food-seeking behavior. Our results showed that mirtazapine attenuated the re-acquisition of cocaine-seeking responses. Our study pointed to the efficacy of mirtazapine in reducing the risk of drug relapse during abstinence, suggesting for its potential use as a novel pharmacological agent to treat drug abuse. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Controlled Attenuation Parameter And Alcoholic Hepatic Steatosis

    DEFF Research Database (Denmark)

    Thiele, Maja; Rausch, Vanessa; Fluhr, Gabriele

    2018-01-01

    BACKGROUND AND AIMS: Controlled attenuation parameter (CAP) is a novel non-invasive measure of hepatic steatosis, but has not been evaluated in alcoholic liver disease. We therefore aimed to validate CAP for assessment of biopsy-verified alcoholic steatosis and to study the effect of alcohol deto...

  11. Heat-accelerated radioinactivation of attenuated poliovirus

    International Nuclear Information System (INIS)

    Dugan, V.L.; Trujillo, R.

    1975-01-01

    Attenuated poliovirus is inactivated in a synergistic manner when exposed simultaneously to heat and ionizing radiation. The synergistic response is observed in both the thermally labile and stable forms of the virus. A three-term kinetic model may be used to describe the inactivation response of the virus in a thermal and/or ionizing radiation environment. (orig.) [de

  12. GPR measurements of attenuation in concrete

    Science.gov (United States)

    Eisenmann, David; Margetan, Frank J.; Pavel, Brittney

    2015-03-01

    Ground-penetrating radar (GPR) signals from concrete structures are affected by several phenomenon, including: (1) transmission and reflection coefficients at interfaces; (2) the radiation patterns of the antenna(s) being used; and (3) the material properties of concrete and any embedded objects. In this paper we investigate different schemes for determining the electromagnetic (EM) attenuation of concrete from measured signals obtained using commercially-available GPR equipment. We adapt procedures commonly used in ultrasonic inspections where one compares the relative strengths of two or more signals having different travel paths through the material of interest. After correcting for beam spread (i.e., diffraction), interface phenomena, and equipment amplification settings, any remaining signal differences are assumed to be due to attenuation thus allowing the attenuation coefficient (say, in dB of loss per inch of travel) to be estimated. We begin with a brief overview of our approach, and then discuss how diffraction corrections were determined for our two 1.6 GHz GPR antennas. We then present results of attenuation measurements for two types of concrete using both pulse/echo and pitch/catch measurement setups.

  13. GPR measurements of attenuation in concrete

    International Nuclear Information System (INIS)

    Eisenmann, David; Margetan, Frank J.; Pavel, Brittney

    2015-01-01

    Ground-penetrating radar (GPR) signals from concrete structures are affected by several phenomenon, including: (1) transmission and reflection coefficients at interfaces; (2) the radiation patterns of the antenna(s) being used; and (3) the material properties of concrete and any embedded objects. In this paper we investigate different schemes for determining the electromagnetic (EM) attenuation of concrete from measured signals obtained using commercially-available GPR equipment. We adapt procedures commonly used in ultrasonic inspections where one compares the relative strengths of two or more signals having different travel paths through the material of interest. After correcting for beam spread (i.e., diffraction), interface phenomena, and equipment amplification settings, any remaining signal differences are assumed to be due to attenuation thus allowing the attenuation coefficient (say, in dB of loss per inch of travel) to be estimated. We begin with a brief overview of our approach, and then discuss how diffraction corrections were determined for our two 1.6 GHz GPR antennas. We then present results of attenuation measurements for two types of concrete using both pulse/echo and pitch/catch measurement setups

  14. Anethum Graveolens Linn (Umbelliferae) Extract Attenuates Stress ...

    African Journals Online (AJOL)

    Anethum Graveolens Linn (Umbelliferae) Extract Attenuates Stress-induced Urinary Biochemical Changes and Improves Cognition in Scopolamineinduced Amnesic Rats. ... Conclusion: The aqueous extract of A. graveolens exhibited significant anti-stress, antioxidant and memory enhancing activities. The study provides a ...

  15. Electron attenuation characteristics of LiF

    Energy Technology Data Exchange (ETDEWEB)

    Paliwal, B R [Wisconsin Univ., Madison (USA). Div. of Clinical Oncology; Almond, P R

    1976-08-01

    The results of a study, indicating the exponential nature of the attenuation of electrons in LiF, are reported. This conclusion holds good not only for the monoenergetic electrons obtained from several pure ..beta.. emitters but also for the high energy electron beams delivered by radiotherapy facilities.

  16. Microwave attenuation with composite of copper microwires

    International Nuclear Information System (INIS)

    Gorriti, A.G.; Marin, P.; Cortina, D.; Hernando, A.

    2010-01-01

    It is shown that copper microwires composite media attenuates microwave reflection of metallic surfaces. We show how the distance to the metallic surface, as well as the length and volume fraction of microwires, determine the frequency of maximum absorption and the return loss level. Furthermore, we were able to fit the experimental results with a theoretical model based on Maxwell-Garnett mixing formula.

  17. Microwave attenuation with composite of copper microwires

    Energy Technology Data Exchange (ETDEWEB)

    Gorriti, A.G.; Marin, P. [Instituto de Magnetismo Aplicado, (UCM-ADIF-CSIC) and Departamento de Fisica de Materiales (UCM). P.O. Box 155, Las Rozas, Madrid 28230 (Spain); Cortina, D. [Micromag S.L., Las Rozas, Madrid 28230 (Spain); Hernando, A., E-mail: antonio.hernando@adif.e [Instituto de Magnetismo Aplicado, (UCM-ADIF-CSIC) and Departamento de Fisica de Materiales (UCM). P.O. Box 155, Las Rozas, Madrid 28230 (Spain); Micromag S.L., Las Rozas, Madrid 28230 (Spain)

    2010-05-15

    It is shown that copper microwires composite media attenuates microwave reflection of metallic surfaces. We show how the distance to the metallic surface, as well as the length and volume fraction of microwires, determine the frequency of maximum absorption and the return loss level. Furthermore, we were able to fit the experimental results with a theoretical model based on Maxwell-Garnett mixing formula.

  18. Touch Attenuates Infants' Physiological Reactivity to Stress

    Science.gov (United States)

    Feldman, Ruth; Singer, Magi; Zagoory, Orna

    2010-01-01

    Animal studies demonstrate that maternal touch and contact regulate infant stress, and handling during periods of maternal deprivation attenuates the stress response. To measure the effects of touch on infant stress reactivity during simulated maternal deprivation, 53 dyads were tested in two paradigms: still-face (SF) and still-face with maternal…

  19. Airborne non-contact and contact broadband ultrasounds for frequency attenuation profile estimation of cementitious materials.

    Science.gov (United States)

    Gosálbez, J; Wright, W M D; Jiang, W; Carrión, A; Genovés, V; Bosch, I

    2018-08-01

    In this paper, the study of frequency-dependent ultrasonic attenuation in strongly heterogeneous cementitious materials is addressed. To accurately determine the attenuation over a wide frequency range, it is necessary to have suitable excitation techniques. We have analysed two kinds of ultrasound techniques: contact ultrasound and airborne non-contact ultrasound. The mathematical formulation for frequency-dependent attenuation has been established and it has been revealed that each technique may achieve similar results but requires specific different calibration processes. In particular, the airborne non-contact technique suffers high attenuation due to energy losses at the air-material interfaces. Thus, its bandwidth is limited to low frequencies but it does not require physical contact between transducer and specimen. In contrast, the classical contact technique can manage higher frequencies but the measurement depends on the pressure between the transducer and the specimen. Cement specimens have been tested with both techniques and frequency attenuation dependence has been estimated. Similar results were achieved at overlapping bandwidth and it has been demonstrated that the airborne non-contact ultrasound technique could be a viable alternative to the classical contact technique. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Single photon emission computed tomography using a regularizing iterative method for attenuation correction

    International Nuclear Information System (INIS)

    Soussaline, Francoise; Cao, A.; Lecoq, G.

    1981-06-01

    An analytically exact solution to the attenuated tomographic operator is proposed. Such a technique called Regularizing Iterative Method (RIM) belongs to the iterative class of procedures where a priori knowledge can be introduced on the evaluation of the size and shape of the activity domain to be reconstructed, and on the exact attenuation distribution. The relaxation factor used is so named because it leads to fast convergence and provides noise filtering for a small number of iteractions. The effectiveness of such a method was tested in the Single Photon Emission Computed Tomography (SPECT) reconstruction problem, with the goal of precise correction for attenuation before quantitative study. Its implementation involves the use of a rotating scintillation camera based SPECT detector connected to a mini computer system. Mathematical simulations of cylindical uniformly attenuated phantoms indicate that in the range of a priori calculated relaxation factor a fast converging solution can always be found with a (contrast) accuracy of the order of 0.2 to 4% given that numerical errors and noise are or not, taken into account. The sensitivity of the (RIM) algorithm to errors in the size of the reconstructed object and in the value of the attenuation coefficient μ was studied, using the same simulation data. Extreme variations of +- 15% in these parameters will lead to errors of the order of +- 20% in the quantitative results. Physical phantoms representing a variety of geometrical situations were also studied

  1. Analysis of biological samples by x-ray attenuation measurements

    International Nuclear Information System (INIS)

    Cesareo, R.

    1988-01-01

    Over the last few years there has been an increasing interest in X-ray attenuation measurements, mainly due to the enormous development of computer assisted tomography (CAT). With CAT, analytical information concerning the density and the mean atomic number distributions in a sample is deduced from a large number of attenuation measurements. Particular transmission methods developed, based on the differential attenuation method are discussed. The theoretical background for attenuation of radiation and for differential attenuation of radiation is given. Details about the generation of monoenergetic X-rays are discussed. Applications of attenuation measurements in the field of Medicine are presented

  2. Active inference, sensory attenuation and illusions.

    Science.gov (United States)

    Brown, Harriet; Adams, Rick A; Parees, Isabel; Edwards, Mark; Friston, Karl

    2013-11-01

    Active inference provides a simple and neurobiologically plausible account of how action and perception are coupled in producing (Bayes) optimal behaviour. This can be seen most easily as minimising prediction error: we can either change our predictions to explain sensory input through perception. Alternatively, we can actively change sensory input to fulfil our predictions. In active inference, this action is mediated by classical reflex arcs that minimise proprioceptive prediction error created by descending proprioceptive predictions. However, this creates a conflict between action and perception; in that, self-generated movements require predictions to override the sensory evidence that one is not actually moving. However, ignoring sensory evidence means that externally generated sensations will not be perceived. Conversely, attending to (proprioceptive and somatosensory) sensations enables the detection of externally generated events but precludes generation of actions. This conflict can be resolved by attenuating the precision of sensory evidence during movement or, equivalently, attending away from the consequences of self-made acts. We propose that this Bayes optimal withdrawal of precise sensory evidence during movement is the cause of psychophysical sensory attenuation. Furthermore, it explains the force-matching illusion and reproduces empirical results almost exactly. Finally, if attenuation is removed, the force-matching illusion disappears and false (delusional) inferences about agency emerge. This is important, given the negative correlation between sensory attenuation and delusional beliefs in normal subjects--and the reduction in the magnitude of the illusion in schizophrenia. Active inference therefore links the neuromodulatory optimisation of precision to sensory attenuation and illusory phenomena during the attribution of agency in normal subjects. It also provides a functional account of deficits in syndromes characterised by false inference

  3. Empirical formulae for mass attenuation and energy absorption coefficients from 1 keV to 20 MeV

    International Nuclear Information System (INIS)

    Manjunatha, H.C.; Sowmya, N.; Seenappa, L.; Sridhar, K.N.; Hanumantharayappa, C.

    2017-01-01

    Mass attenuation and energy absorption coefficients represents attenuation and absorption of X-rays and gamma rays in the material medium. A new empirical formula is proposed for mass attenuation and energy absorption coefficients in the region 1 < Z < 92 and from 1 keV to 20 MeV. The mass attenuation and energy absorption coefficients do not varies linearly with energy. We have performed the nonlinear regressions/nonlinear least square fittings and proposed the simple empirical relations between mass attenuation coefficients (μ/ρ) and mass energy absorption coefficients (μ en /ρ) and energy. We have compared the values produced by this formula with that of experiments. A good agreement of present formula with the experiments/previous models suggests that the present formulae could be used to evaluate mass attenuation and energy absorption coefficients in the region 1 < Z < 92. This formula is a model-independent formula and is the first of its kind that produces a mass attenuation and energy absorption coefficient values with the only simple input of energy for wide energy range 1 keV - 20 MeV in the atomic number region 1 < Z < 92. This formula is very much useful in the fields of radiation physics and dosimetry

  4. SPECT quantification: a review of the different correction methods with compton scatter, attenuation and spatial deterioration effects

    International Nuclear Information System (INIS)

    Groiselle, C.; Rocchisani, J.M.; Moretti, J.L.; Dreuille, O. de; Gaillard, J.F.; Bendriem, B.

    1997-01-01

    SPECT quantification: a review of the different correction methods with Compton scatter attenuation and spatial deterioration effects. The improvement of gamma-cameras, acquisition and reconstruction software opens new perspectives in term of image quantification in nuclear medicine. In order to meet the challenge, numerous works have been undertaken in recent years to correct for the different physical phenomena that prevent an exact estimation of the radioactivity distribution. The main phenomena that have to betaken into account are scatter, attenuation and resolution. In this work, authors present the physical basis of each issue, its consequences on quantification and the main methods proposed to correct them. (authors)

  5. Improvement of quantitation in SPECT: Attenuation and scatter correction using non-uniform attenuation data

    International Nuclear Information System (INIS)

    Mukai, T.; Torizuka, K.; Douglass, K.H.; Wagner, H.N.

    1985-01-01

    Quantitative assessment of tracer distribution with single photon emission computed tomography (SPECT) is difficult because of attenuation and scattering of gamma rays within the object. A method considering the source geometry was developed, and effects of attenuation and scatter on SPECT quantitation were studied using phantoms with non-uniform attenuation. The distribution of attenuation coefficients (μ) within the source were obtained by transmission CT. The attenuation correction was performed by an iterative reprojection technique. The scatter correction was done by convolution of the attenuation corrected image and an appropriate filter made by line source studies. The filter characteristics depended on μ and SPEC measurement at each pixel. The SPECT obtained by this method showed the most reasonable results than the images reconstructed by other methods. The scatter correction could compensate completely for a 28% scatter components from a long line source, and a 61% component for thick and extended source. Consideration of source geometries was necessary for effective corrections. The present method is expected to be valuable for the quantitative assessment of regional tracer activity

  6. Pramana – Journal of Physics | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 70; Issue 4. Issue front cover ... pp 565-574 Research Articles ... pp 575-585 Research Articles .... Attenuation studies near K-absorption edges using Compton scatteredAm gamma rays.

  7. Pervious concrete physical characteristics and effectiveness in stormwater pollution reduction.

    Science.gov (United States)

    2016-04-01

    The objective of this research was to investigate the physical/chemical and water flow characteristics of various previous concrete : mixes made of different concrete materials and their effectiveness in attenuating water pollution. Four pervious con...

  8. Cross-shore gradients of physical disturbance in mangroves: implications for seedling establishment

    NARCIS (Netherlands)

    Balke, T.; Bouma, T.; Herman, P.M.J.; Horstman, E.M.; Sudtongkong, C.; Webb, E.L.

    2013-01-01

    Mangroves may grow in an active sedimentary environment and are therefore closely linked to physical coastal processes. Seedlings colonize dynamic tidal flats, after which mangroves have the potential to change their physical environment by attenuating hydrodynamic energy and trapping sediments.

  9. Overview of recent developments in attenuation models

    International Nuclear Information System (INIS)

    Riera, J.D.

    2001-01-01

    Attenuation equations predict features of the seismic motion, such as the horizontal and vertical peak ground accelerations (PGA), the peak ground velocities (PGV) and the 5% damped spectral acceleration response (SA), in terms of the earthquake magnitude and distance from source to site. Occasionally other factors, like the type of faulting, are considered in the attenuation expressions. An overview of recent developments in this field is presented in the paper, including a discussion of the applicability of various models for short source to site distances. In such a case, i.e. in the neighbourhood of the epicentral region, which is of utmost importance in Nuclear Power Plant applications, the use of two parameters to define the earthquake size is suggested, instead of the single parameter, a magnitude scale. Recent evidence of the importance in such situations of so-called directivity effects, which require a more complete description of the focal mechanism, completes the paper. (author)

  10. P300 is attenuated during dissociative episodes.

    Science.gov (United States)

    Kirino, Eiji

    2006-02-01

    The present study examined the pathophysiology of dissociative phenomena using the P300 component of event-related potentials, quantitative electroencephalography (QEEG), and morphology measures of computed tomography scan. Event-related potentials during an auditory oddball paradigm and QEEG in resting state were recorded. Patients exhibited attenuation of P300 amplitudes compared with controls during dissociative episodes, but exhibited recovery to control levels in remission. Patients had a larger Sylvian fissure-brain ratio than did controls. QEEG findings revealed no significant differences between the patients and controls or between episodes and remission in the patient group. Attenuation of the P300 can be interpreted as the result of a negative feedback loop from the medial temporal lobe to the cortex, which decreases the amount of information flow, allocation of attentional resources, and updating of working memory to avoid both excessive long-term memory system activity in medial temporal lobe and resurgence of affect-laden memories.

  11. Indoor signal attenuation assessment via fuzzy logic

    Directory of Open Access Journals (Sweden)

    Alexandre de Assis Mota

    2011-09-01

    Full Text Available This work focuses on the analysis of signal´s attenuation in indoor environments using a fuzzy logic approach based on the Shadowing Signal Propagation Model (SSPM. The SSPM allows the characterization of the attenuation caused by the environment through the ? parameter present in this model. In addition to this, the Fuzzy Logic provides a form of approximate reasoning that allows the treatment of problems with incomplete, vague and imprecise information. Also, it offers a simple way to obtain a possible solution for a problem using the heuristic knowledge about a particular situation. The results show that the methodology produced satisfactory results, close to the ones yielded by experimental methods.

  12. Attenuation of gamma radiation in concrete shields

    International Nuclear Information System (INIS)

    Azevedo e Souza, A.C. de.

    1978-12-01

    The attenuation characteristics of γ radiation in concrete layers considering their mechanical resistence and densities were determined. A 137 Cs source was used in a 'good geometry' arrangement to eliminate the effects of the buildup factor. The ordinary and the heavy concrete were irradiated and for the latter it was used as additives iron ore and Fe 2 O 3 pellets in various grain sizes. The detection system consisted of a 2' x 2' NaI (Tl) crystal coupled to a photomultiplier tube and the associated electronic equipment. FORTRAN programs were used for determining the absorption coefficients and the attenuation factors. These programs calculate photopeak areas eliminating all contributions due to Compton effect and background. (Author) [pt

  13. Anomalies of ultrasound attenuation in metals under hydrostatic pressure

    International Nuclear Information System (INIS)

    Galkin, A.A.; Datsko, O.I.; Varyukhin, V.N.; Pilipenko, N.P.

    1978-01-01

    Ultrasonic attenuation was measured in polycrystal specimens of molybdenum, chromium and zinc under hydrostatic pressure up to 6 kbar. On the plot of ultrasound attenuation dependence on the pressure in molybdenum the maxima are observed under the pressure of 2 kbar. The anomaly of ultrasound attenuation is shown to connect only with brittle-ductile transtion

  14. Phonic Attenuation due to Screen-Barriers

    Directory of Open Access Journals (Sweden)

    Vasile Bacria

    2011-10-01

    Full Text Available The technique of noise decreasing admits two basic approaches: an active approach and a passive one. In the frame of passive method one can count the employment of screen-barriers. In this paper we present some considerations on sound attenuation due to screen-barriers emphasizing the elements which influence it. The elucidation of these elements is made by measurements. The obtained results can be applied in every other practical situation concerning the protection against noise.

  15. Mid-European seismic attenuation anomaly

    Czech Academy of Sciences Publication Activity Database

    Málek, Jiří; Brokešová, J.; Vackář, Jiří

    2017-01-01

    Roč. 712, AUG 21 (2017), s. 557-577 ISSN 0040-1951 Grant - others:AV ČR(CZ) StrategieAV21/4 Program:StrategieAV Institutional support: RVO:67985891 Keywords : seismic wave attenuation * peak ground motion * H/V ratio Subject RIV: DC - Siesmology, Volcanology, Earth Structure OBOR OECD: Geology Impact factor: 2.693, year: 2016

  16. Attenuation and scatter correction in SPECT

    International Nuclear Information System (INIS)

    Pant, G.S.; Pandey, A.K.

    2000-01-01

    While passing through matter, photons undergo various types of interactions. In the process, some photons are completely absorbed, some are scattered in different directions with or without any change in their energy and some pass through unattenuated. These unattenuated photons carry the information with them. However, the image data gets corrupted with attenuation and scatter processes. This paper deals with the effect of these two processes in nuclear medicine images and suggests the methods to overcome them

  17. Natural attenuation of biogas in landfill covers

    International Nuclear Information System (INIS)

    Cossu, R.; Privato, A.; Raga, R.

    2005-01-01

    In the risk evaluation of uncontrolled biogas emissions from landfills, the process of natural attenuation in landfill covers assumes a very important role. The capacity of biogas oxidation in the cover soils seems to be the most important control to mitigate the biogas emission during the aftercare period when the biogas collection system might fail. In the present paper laboratory experiences on lab columns to study the biogas oxidation are discussed [it

  18. Radiation attenuation gauge with magnetically coupled source

    International Nuclear Information System (INIS)

    Wallace, S.A.

    1978-01-01

    Disclosed is a radiation attenuation gauge for measuring thickness and density of a material which includes, in combination, a source of gamma radiation contained within a housing of magnetic or ferromagnetic material, and a means for measuring the intensity of gamma radiation. The measuring means has an aperture and magnetic means disposed adjacent to the aperture for attracting and holding the housed source in position before the aperture. The material to be measured is placed between the source and the measuring means

  19. Wave attenuation charcteristics of tethered float system

    Digital Repository Service at National Institute of Oceanography (India)

    Vethamony, P.

    incident wave height transmitted wave height G wave number float mass number of rows of floats drag power transmitted wave power incident wave power 111 112 P. Vethamony float radius wave period time velocity and acceleration of fluid... particles, respectively wave attenuation in percentage displacement, velocity and acceleration of float, respectively amplitude of float displacement added mass damping coefficient fluid particle displacement amplitude of fluid particle displacement...

  20. The attenuation of the periodic table

    International Nuclear Information System (INIS)

    Cook, N.D.

    1990-01-01

    Unique among models of nuclear structure, the face-centered-cubic (FCC) lattice model predicts the attenuation of the periodic table at Z < 110 and the impossibility of superheavy nuclei. The total binding energies of superheavy nuclei in the FCC model (109 < Z < 127) were calculated on the basis of parameters obtained from a least-squares best-fit for 914 nuclei (Z < 99). No indication of increased stability is found for any of the transuranic elements

  1. Broadband Vibration Attenuation Using Hybrid Periodic Rods

    Directory of Open Access Journals (Sweden)

    S. Asiri

    2008-12-01

    Full Text Available This paper presents both theoretically and experimentally a new kind of a broadband vibration isolator. It is a table-like system formed by four parallel hybrid periodic rods connected between two plates. The rods consist of an assembly of periodic cells, each cell being composed of a short rod and piezoelectric inserts. By actively controlling the piezoelectric elements, it is shown that the periodic rods can efficiently attenuate the propagation of vibration from the upper plate to the lower one within critical frequency bands and consequently minimize the effects of transmission of undesirable vibration and sound radiation. In such a system, longitudinal waves can propagate from the vibration source in the upper plate to the lower one along the rods only within specific frequency bands called the "Pass Bands" and wave propagation is efficiently attenuated within other frequency bands called the "Stop Bands". The spectral width of these bands can be tuned according to the nature of the external excitation. The theory governing the operation of this class of vibration isolator is presented and their tunable filtering characteristics are demonstrated experimentally as functions of their design parameters. This concept can be employed in many applications to control the wave propagation and the force transmission of longitudinal vibrations both in the spectral and spatial domains in an attempt to stop/attenuate the propagation of undesirable disturbances.

  2. Novel Intriguing Strategies Attenuating to Sarcopenia

    Directory of Open Access Journals (Sweden)

    Kunihiro Sakuma

    2012-01-01

    Full Text Available Sarcopenia, the age-related loss of skeletal muscle mass, is characterized by a deterioration of muscle quantity and quality leading to a gradual slowing of movement, a decline in strength and power, increased risk of fall-related injury, and, often, frailty. Since sarcopenia is largely attributed to various molecular mediators affecting fiber size, mitochondrial homeostasis, and apoptosis, the mechanisms responsible for these deleterious changes present numerous therapeutic targets for drug discovery. Resistance training combined with amino acid-containing supplements is often utilized to prevent age-related muscle wasting and weakness. In this review, we summarize more recent therapeutic strategies (myostatin or proteasome inhibition, supplementation with eicosapentaenoic acid (EPA or ursolic acid, etc. for counteracting sarcopenia. Myostatin inhibitor is the most advanced research with a Phase I/II trial in muscular dystrophy but does not try the possibility for attenuating sarcopenia. EPA and ursolic acid seem to be effective as therapeutic agents, because they attenuate the degenerative symptoms of muscular dystrophy and cachexic muscle. The activation of peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α in skeletal muscle by exercise and/or unknown supplementation would be an intriguing approach to attenuating sarcopenia. In contrast, muscle loss with age may not be influenced positively by treatment with a proteasome inhibitor or antioxidant.

  3. Recommendations for processing atmospheric attenuated backscatter profiles from Vaisala CL31 ceilometers

    Science.gov (United States)

    Kotthaus, Simone; O'Connor, Ewan; Münkel, Christoph; Charlton-Perez, Cristina; Haeffelin, Martial; Gabey, Andrew M.; Grimmond, C. Sue B.

    2016-08-01

    Ceilometer lidars are used for cloud base height detection, to probe aerosol layers in the atmosphere (e.g. detection of elevated layers of Saharan dust or volcanic ash), and to examine boundary layer dynamics. Sensor optics and acquisition algorithms can strongly influence the observed attenuated backscatter profiles; therefore, physical interpretation of the profiles requires careful application of corrections. This study addresses the widely deployed Vaisala CL31 ceilometer. Attenuated backscatter profiles are studied to evaluate the impact of both the hardware generation and firmware version. In response to this work and discussion within the CL31/TOPROF user community (TOPROF, European COST Action aiming to harmonise ground-based remote sensing networks across Europe), Vaisala released new firmware (versions 1.72 and 2.03) for the CL31 sensors. These firmware versions are tested against previous versions, showing that several artificial features introduced by the data processing have been removed. Hence, it is recommended to use this recent firmware for analysing attenuated backscatter profiles. To allow for consistent processing of historic data, correction procedures have been developed that account for artefacts detected in data collected with older firmware. Furthermore, a procedure is proposed to determine and account for the instrument-related background signal from electronic and optical components. This is necessary for using attenuated backscatter observations from any CL31 ceilometer. Recommendations are made for the processing of attenuated backscatter observed with Vaisala CL31 sensors, including the estimation of noise which is not provided in the standard CL31 output. After taking these aspects into account, attenuated backscatter profiles from Vaisala CL31 ceilometers are considered capable of providing valuable information for a range of applications including atmospheric boundary layer studies, detection of elevated aerosol layers, and model

  4. Elastic Dispersion and Attenuation in Fully Saturated Sandstones: Role of Mineral Content, Porosity, and Pressures

    Science.gov (United States)

    Pimienta, Lucas; Borgomano, Jan V. M.; Fortin, Jérôme; Guéguen, Yves

    2017-12-01

    Because measuring the frequency dependence of elastic properties in the laboratory is a technical challenge, not enough experimental data exist to test the existing theories. We report measurements of three fluid-saturated sandstones over a broad frequency band: Wilkenson, Berea, and Bentheim sandstones. Those sandstones samples, chosen for their variable porosities and mineral content, are saturated by fluids of varying viscosities. The samples elastic response (Young's modulus and Poisson's ratio) and hydraulic response (fluid flow out of the sample) are measured as a function of frequency. Large dispersion and attenuation phenomena are observed over the investigated frequency range. For all samples, the variation at lowest frequency relates to a large fluid flow directly measured out of the rock samples. These are the cause (i.e., fluid flow) and consequence (i.e., dispersion/attenuation) of the transition between drained and undrained regimes. Consistently, the characteristic frequency correlates with permeability for each sandstone. Beyond this frequency, a second variation is observed for all samples, but the rocks behave differently. For Berea sandstone, an onset of dispersion/attenuation is expected from both Young's modulus and Poisson's ratio at highest frequency. For Bentheim and Wilkenson sandstones, however, only Young's modulus shows dispersion/attenuation phenomena. For Wilkenson sandstone, the viscoelastic-like dispersion/attenuation response is interpreted as squirt flow. For Bentheim sandstone, the second effect does not fully follow such response, which could be due to a lower accuracy in the measured attenuation or to the occurence of another physical effect in this rock sample.

  5. Attenuation tomography in the rupture area of the 2010 M8.8 Maule, Chile, earthquake

    Science.gov (United States)

    Heather-Smith, Helen; Rietbrock, Andreas

    2016-04-01

    In recent years several seismological studies have developed a detailed image of the megathrust interface between the subducting Nazca plate and and the overriding South American plate in the rupture area of the 2010 M8.8 Maule, Chile, earthquake. Hicks et al. (2014) have published a high resolution 3D seismic tomography model and characterised the different regimes acting along the interface based on their seismic properties. A more detailed study by Moreno et al. (2014) showed that the seismic Vp/Vs ratio and inter-seismic locking determined from GPS measurements are correlated. Together these observations open up the possibility to map the rupture potential of possible future earthquakes, although the underlying processes are yet not fully understood and a more in depth analysis of other physical properties is needed. 3D seismic attenuation structure as well as seismic stress-drop distribution based on the aftershock seismicity are providing independent data sets to better constrain the physical processes acting along the subduction zone interface. As seismic attenuation is particularly sensitive to fluid saturation it opens up the possibility to study more directly the influence of fluids on aftershock activity as compared to standard velocity tomography studies. Based on our event catalogue of approximately 30,000 aftershocks we are currently selecting the most appropriate data set for the staggered 3D attenuation tomography. The inverted attenuation model will then be used to calculate seismic stress drop values for the complete aftershock catalogue. We will present our preliminary 3D attenuation model together with our stress drop estimates and compare our finding to the 3D velocity structure and slip distribution.

  6. Determination of the attenuation map in emission tomography

    CERN Document Server

    Zaidi, H

    2002-01-01

    Reliable attenuation correction methods for quantitative emission computed tomography (ECT) require accurate delineation of the body contour and often necessitate knowledge of internal anatomical structure. Two broad classes of methods have been used to calculate the attenuation map referred to as "transmissionless" and transmission-based attenuation correction techniques. While calculated attenuation correction belonging to the first class of methods is appropriate for brain studies, more adequate methods must be performed in clinical applications where the attenuation coefficient distribution is not known a priori, and for areas of inhomogeneous attenuation such as the chest. Measured attenuation correction overcomes this problem and utilizes different approaches to determine this map including transmission scanning, segmented magnetic resonance images or appropriately scaled X-ray CT scans acquired either independently on separate or simultaneously on multimodality imaging systems. Combination of data acqu...

  7. Attenuation correction using simultaneous emission - transmission tomography

    International Nuclear Information System (INIS)

    Ljubenov, V.; Marinkovic, P.

    1998-01-01

    In order to reduce degrading influence of attenuation on SPECT image quality, possibility for correction, based on simultaneous emission / transmission measurements, is discussed. Numerical photon transport simulations through the phantom and acquisition of of tomographic projections are performed by using Monte Carlo code MCNP-4A. Amount of contamination in transmission data due to photon Compton scattering for emission energy window is specially analyzed and appropriate spatial depending 'noise / signal' factors for three different external sources, applied with Tc-99m, are determined (author)

  8. Effects of Attenuation of Gas Hydrate-bearing Sediments on Seismic Data: Example from Mallik, Northwest Territories, Canada

    Science.gov (United States)

    Bellefleur, G.; Riedel, M.; Brent, T.

    2007-05-01

    Wave attenuation is an important physical property of hydrate-bearing sediments that is rarely taken into account in site characterization with seismic data. We present a field example showing improved images of hydrate- bearing sediments on seismic data after compensation of attenuation effects. Compressional quality factors (Q) are estimated from zero-offset Vertical Seismic Profiling data acquired at Mallik, Northwest Territories, Canada. During the last 10 years, two internationally-partnered research drilling programs have intersected three major intervals of sub-permafrost gas hydrates at Mallik, and have successfully extracted core samples containing significant amount of gas hydrates. Individual gas hydrate intervals are up to 40m in thickness and are characterized by high in situ gas hydrate saturation, sometimes exceeding 80% of pore volume of unconsolidated clastic sediments having average porosities ranging from 25% to 40%. The Q-factors obtained from the VSP data demonstrate significant wave attenuation for permafrost and hydrate- bearing sediments. These results are in agreement with previous attenuation estimates from sonic logs and crosshole data at different frequency intervals. The Q-factors obtained from VSP data were used to compensate attenuation effects on surface 3D seismic data acquired over the Mallik gas hydrate research wells. Intervals of gas hydrate on surface seismic data are characterized by strong reflectivity and effects from attenuation are not perceptible from a simple visual inspection of the data. However, the application of an inverse Q-filter increases the resolution of the data and improves correlation with log data, particularly for the shallowest gas hydrate interval. Compensation of the attenuation effects of the permafrost likely explains most of the improvements for the shallow gas hydrate zone. Our results show that characterization of the Mallik gas hydrates with seismic data not corrected for attenuation would tend to

  9. Nuclear medical physics

    International Nuclear Information System (INIS)

    Williams, L.E.

    1987-01-01

    This three-volume set covers the physical basis of nuclear medicine, and is intended as a source of data for practicing scientists and physicians as well as those beginning their careers or simply studying nuclear medical physics. It leads the reader from quantum theory to the production and attenuation of ionizing radiation; considers dosimetry and the most recent assessment of biological effects of such particles; describes in detail detector materials, signal analysis, and gamma cameras; includes extensive discussions of bone mineral measurement as well as magnetic resonance imaging; covers limited angle, rotating camera, and positron tomography; presents quality assurance and statistical theory with an eye toward enhanced departmental operations; and features descriptions of functional imaging and the psychophysical basis of diagnosis

  10. Vinpocetine attenuates lipid accumulation and atherosclerosis formation

    International Nuclear Information System (INIS)

    Cai, Yujun; Li, Jian-Dong; Yan, Chen

    2013-01-01

    Highlights: •Vinpocetine attenuates hyperlipidemia-induced atherosclerosis in a mouse model. •Vinpocetine antagonizes ox-LDL uptake and accumulation in macrophages. •Vinpocetine blocks the induction of ox-LDL receptor LOX-1 in vitro and in vivo. -- Abstract: Atherosclerosis, the major cause of myocardial infarction and stroke, is a chronic arterial disease characterized by lipid deposition and inflammation in the vessel wall. Cholesterol, in low-density lipoprotein (LDL), plays a critical role in the pathogenesis of atherosclerosis. Vinpocetine, a derivative of the alkaloid vincamine, has long been used as a cerebral blood flow enhancer for treating cognitive impairment. Recent study indicated that vinpocetine is a potent anti-inflammatory agent. However, its role in the pathogenesis of atherosclerosis remains unexplored. In the present study, we show that vinpocetine significantly reduced atherosclerotic lesion formation in ApoE knockout mice fed with a high-fat diet. In cultured murine macrophage RAW264.7 cells, vinpocetine markedly attenuated oxidized LDL (ox-LDL) uptake and foam cell formation. Moreover, vinpocetine greatly blocked the induction of ox-LDL receptor 1 (LOX-1) in cultured macrophages as well as in the LOX-1 level in atherosclerotic lesions. Taken together, our data reveal a novel role of vinpocetine in reduction of pathogenesis of atherosclerosis, at least partially through suppressing LOX-1 signaling pathway. Given the excellent safety profile of vinpocetine, this study suggests vinpocetine may be a therapeutic candidate for treating atherosclerosis

  11. Ultra-low acoustoelectric attenuation in graphene

    Science.gov (United States)

    Tang, Chiu-Chun; Chen, Yung-Fu; Ling, D. C.; Chi, C. C.; Chen, Jeng-Chung

    2017-03-01

    We investigate the acoustoelectric properties of graphene and extract its acoustoelectric attenuation Γ as a function of the carrier density n, tuned via ionic liquid gating. Acoustoelectric effects in graphene are induced by launching surface acoustic waves (SAWs) on a piezoelectric LiNbO3 substrate. We measure the acoustoelectric current Iae through graphene and extract the SAW attenuation factor Γ as a function of n. The magnitude of Iae increases with decreasing n when the n is far from the charge neutral point (CNP). When n is tuned across the CNP, Iae first exhibits a local maximum, vanishes at the CNP, and then changes sign in accordance with the associated change in the carrier polarity. By contrast, Γ monotonically increases with decreasing n and reaches a maximum at the CNP. The extracted values of Γ, calibrated at the central frequency of 189 MHz, vary from ˜0.4 m-1 to 6.8 m-1, much smaller than the values for known two-dimensional systems. Data analysis suggests that the evolution of Iae and Γ with n manifests the electronic states of graphene. Our experimental findings provide insightful information for developing innovative graphene-based devices.

  12. Boundary layer attenuation in turbulent sodium flows

    International Nuclear Information System (INIS)

    Tenchine, D.

    1994-01-01

    Temperature fluctuations are produced in the sodium coolant of Liquid Metal Reactors when flows at different temperatures are mixing. That occurs in various areas of the reactor plant, in the primary and the secondary circuits. This paper deals with secondary circuit pipings, specifically the Superphenix steam generator outlet. The possibility of thermal striping in this area is studied because of the mixing of a main 'hot' flow surrounded by a smaller 'cold' flow in the vertical pipe located below the steam generator. This work was developed in the frame of a collaboration between CEA, EDF and FRAMATOME. The purpose of our study is to measure temperature fluctuations in the fluid and on the structures, on a sodium reduced scale model of the outlet region of the steam generator. We want to evidence the boundary layer attenuation by comparing wall and fluid measurements. From these experimental data, we shall propose a methodology to predict the boundary layer attenuation and the temperature fluctuations at the surface of the structure, for pipe flow configurations

  13. Cranking model and attenuation of Coriolis interaction

    International Nuclear Information System (INIS)

    Lyutorovich, N.A.

    1987-01-01

    Description of rotational bands of odd deformed nuclei in the self-consistent Cranking model (SCM) is given. Causes of attenuation of the Coriolis interaction in the nuclei investigated are studied, and account of bound of one-particle degrees of freedom with rotation of the Hartree-Fock-Bogolyubov (HFB) self-consistent method is introduced additionally to SCM for qualitative agreement with experimental data. Merits and shortages of SCM in comparison with the quadruparticle-rotor (QR) model are discussed. All know ways for constructing the Hamiltonian QR model (or analog of such Hamiltonian) on the basis of the microscopic theory are shown to include two more approximations besides others: quasi-particle-rotational interaction leading to pair break is taken into account in the second order of the perturbation theory; some exchange diagrams are neglected among diagrams of the second order according to this interaction. If one makes the same approximations in SCM instead of HFB method, then the dependence of level energies on spin obtained in this case is turned out to be close to the results of the QR model. Besides, the problem on renormalization of matrix elements of quasi-rotational interaction occurs in such nonself-consistent approach as in the QR model. In so far as the similar problem does not occur in SCM, one can make the conclusion that the problem of attenuation of Coriolis interaction involves the approximations given above

  14. Electron attenuation in free, neutral ethane clusters.

    Science.gov (United States)

    Winkler, M; Myrseth, V; Harnes, J; Børve, K J

    2014-10-28

    The electron effective attenuation length (EAL) in free, neutral ethane clusters has been determined at 40 eV kinetic energy by combining carbon 1s x-ray photoelectron spectroscopy and theoretical lineshape modeling. More specifically, theory is employed to form model spectra on a grid in cluster size (N) and EAL (λ), allowing N and λ to be determined by optimizing the goodness-of-fit χ(2)(N, λ) between model and observed spectra. Experimentally, the clusters were produced in an adiabatic-expansion setup using helium as the driving gas, spanning a range of 100-600 molecules in mean cluster size. The effective attenuation length was determined to be 8.4 ± 1.9 Å, in good agreement with an independent estimate of 10 Å formed on the basis of molecular electron-scattering data and Monte Carlo simulations. The aggregation state of the clusters as well as the cluster temperature and its importance to the derived EAL value are discussed in some depth.

  15. Vinpocetine attenuates lipid accumulation and atherosclerosis formation

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Yujun [Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, 601 Elmwood Ave, Rochester, NY 14642 (United States); Li, Jian-Dong [Center for Inflammation, Immunity and Infection, and Department of Biology, Georgia State University, Atlanta, GA 30303 (United States); Yan, Chen, E-mail: Chen_Yan@urmc.rochester.edu [Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, 601 Elmwood Ave, Rochester, NY 14642 (United States)

    2013-05-10

    Highlights: •Vinpocetine attenuates hyperlipidemia-induced atherosclerosis in a mouse model. •Vinpocetine antagonizes ox-LDL uptake and accumulation in macrophages. •Vinpocetine blocks the induction of ox-LDL receptor LOX-1 in vitro and in vivo. -- Abstract: Atherosclerosis, the major cause of myocardial infarction and stroke, is a chronic arterial disease characterized by lipid deposition and inflammation in the vessel wall. Cholesterol, in low-density lipoprotein (LDL), plays a critical role in the pathogenesis of atherosclerosis. Vinpocetine, a derivative of the alkaloid vincamine, has long been used as a cerebral blood flow enhancer for treating cognitive impairment. Recent study indicated that vinpocetine is a potent anti-inflammatory agent. However, its role in the pathogenesis of atherosclerosis remains unexplored. In the present study, we show that vinpocetine significantly reduced atherosclerotic lesion formation in ApoE knockout mice fed with a high-fat diet. In cultured murine macrophage RAW264.7 cells, vinpocetine markedly attenuated oxidized LDL (ox-LDL) uptake and foam cell formation. Moreover, vinpocetine greatly blocked the induction of ox-LDL receptor 1 (LOX-1) in cultured macrophages as well as in the LOX-1 level in atherosclerotic lesions. Taken together, our data reveal a novel role of vinpocetine in reduction of pathogenesis of atherosclerosis, at least partially through suppressing LOX-1 signaling pathway. Given the excellent safety profile of vinpocetine, this study suggests vinpocetine may be a therapeutic candidate for treating atherosclerosis.

  16. Engineering a Light-Attenuating Artificial Iris.

    Science.gov (United States)

    Shareef, Farah J; Sun, Shan; Kotecha, Mrignayani; Kassem, Iris; Azar, Dimitri; Cho, Michael

    2016-04-01

    Discomfort from light exposure leads to photophobia, glare, and poor vision in patients with congenital or trauma-induced iris damage. Commercial artificial iris lenses are static in nature to provide aesthetics without restoring the natural iris's dynamic response to light. A new photo-responsive artificial iris was therefore developed using a photochromic material with self-adaptive light transmission properties and encased in a transparent biocompatible polymer matrix. The implantable artificial iris was designed and engineered using Photopia, a class of photo-responsive materials (termed naphthopyrans) embedded in polyethylene. Photopia was reshaped into annular disks that were spin-coated with polydimethylsiloxane (PDMS) to form our artificial iris lens of controlled thickness. Activated by UV and blue light in approximately 5 seconds with complete reversal in less than 1 minute, the artificial iris demonstrates graded attenuation of up to 40% of visible and 60% of UV light. There optical characteristics are suitable to reversibly regulate the incident light intensity. In vitro cell culture experiments showed up to 60% cell death within 10 days of exposure to Photopia, but no significant cell death observed when cultured with the artificial iris with protective encapsulation. Nuclear magnetic resonance spectroscopy confirmed these results as there was no apparent leakage of potentially toxic photochromic material from the ophthalmic device. Our artificial iris lens mimics the functionality of the natural iris by attenuating light intensity entering the eye with its rapid reversible change in opacity and thus potentially providing an improved treatment option for patients with iris damage.

  17. Unfocused beam patterns in nonattenuating and attenuating fluids

    International Nuclear Information System (INIS)

    Goldstein, Albert

    2004-01-01

    The most important aspect of an ultrasound measuring system is knowledge of the transducer beam pattern. At all depths accurate single integral equations have been derived for the full beam pattern of steady state unfocused circular flat piston sources radiating into nonattenuating and attenuating fluids. The axial depth of the beginning of the unattenuated beam pattern far field is found to be at 6.41Y 0 . The unattenuated single integral equations are identical to a Jinc function directivity term at this and deeper depths. For attenuating fluids values of α and z are found that permit the attenuated axial pressure to be represented by a plane wave multiplicative exponential attenuation factor. This knowledge will aid in the experimental design of highly accurate attenuation measurements. Accurate single integral equations for the attenuated full beam pattern are derived using complex Bessel functions

  18. An acoustic eikonal equation for attenuating VTI media

    KAUST Repository

    Hao, Qi

    2016-09-06

    We present an acoustic eikonal equation governing the complex-valued travel time of P-waves in attenuating, transversely isotropic media with a vertical symmetry axis (VTI). This equation is based on the assumption that the Pwave complex-valued travel time is independent of the Swave velocity parameter v in Thomsen\\'s notation and the attenuation coefficient A in the Thomsen-type notation for attenuating VTI media. We combine perturbation theory and Shanks transform to develop practical approximations to the attenuating acoustic eikonal equation, capable of admitting analytical description of the attenuation in homogeneous media. For a horizontal, attenuating VTI layer, we also derive non-hyperbolic approximations for the real and imaginary parts of the complex-valued reflection travel time.

  19. Determination of beta attenuation coefficients by means of timing method

    International Nuclear Information System (INIS)

    Ermis, E.E.; Celiktas, C.

    2012-01-01

    Highlights: ► Beta attenuation coefficients of absorber materials were found in this study. ► For this process, a new method (timing method) was suggested. ► The obtained beta attenuation coefficients were compatible with the results from the traditional one. ► The timing method can be used to determine beta attenuation coefficient. - Abstract: Using a counting system with plastic scintillation detector, beta linear and mass attenuation coefficients were determined for bakelite, Al, Fe and plexiglass absorbers by means of timing method. To show the accuracy and reliability of the obtained results through this method, the coefficients were also found via conventional energy method. Obtained beta attenuation coefficients from both methods were compared with each other and the literature values. Beta attenuation coefficients obtained through timing method were found to be compatible with the values obtained from conventional energy method and the literature.

  20. Characteristics of Earthquake Ground Motion Attenuation in Korea and Japan

    International Nuclear Information System (INIS)

    Choi, In-Kil; Choun, Young-Sun; Nakajima, Masato; Ohtori, Yasuki; Yun, Kwan-Hee

    2006-01-01

    The characteristics of a ground motion attenuation in Korea and Japan were estimated by using the earthquake ground motions recorded at the equal distance observation station by KMA, K-NET and KiK-net of Korea and Japan. The ground motion attenuation equations proposed for Korea and Japan were evaluated by comparing the predicted value for the Fukuoka earthquake with the observed records. The predicted values from the attenuation equations show a good agreement with the observed records and each other. It can be concluded from this study that the ground motion attenuation equations can be used for the prediction of strong ground motion attenuation and for an evaluation of the attenuation equations proposed for Korea

  1. Fuselage panel noise attenuation by piezoelectric switching control

    International Nuclear Information System (INIS)

    Makihara, Kanjuro; Onoda, Junjiro; Minesugi, Kenji; Miyakawa, Takeya

    2010-01-01

    This paper describes a problem that we encountered in our noise attenuation project and our solution for it. We intend to attenuate low-frequency noise that transmits through aircraft fuselage panels. Our method of noise attenuation is implemented with a piezoelectric semi-active system having a selective switch instead of an active energy-supply system. The semi-active controller is based on the predicted sound pressure distribution obtained from acoustic emission analysis. Experiments and numerical simulations demonstrate that the semi-active method attenuates acoustic levels of not only the simple monochromatic noise but also of broadband noise. We reveal that tuning the electrical parameters in the circuit is the key to effective noise attenuation, to overcome the acoustic excitation problem due to sharp switching actions, as well as to control chattering problems. The results obtained from this investigation provide meaningful insights into designing noise attenuation systems for comfortable aircraft cabin environments

  2. An attenuated projector-backprojector for iterative SPECT reconstruction

    International Nuclear Information System (INIS)

    Gullberg, G.T.; Pelc, N.J.; Huesman, R.H.; Budinger, T.F.; Malko, J.A.

    1985-01-01

    A new ray-driven projector-backprojector which can easily be adapted for hardware implementation is described and simulated in software. The projector-backprojector discretely models the attenuated Radon transform of a source distributed within an attenuating medium as line integrals of discrete pixels, obtained using the standard sampling technique of averaging the emission source or attenuation distribution over small square regions. Attenuation factors are calculated for each pixel during the projection and backprojection operations instead of using precalculated values. The calculation of the factors requires a specification of the attenuation distribution, estimated either from an assumed constant distribution and an approximate body outline or from transmission measurements. The distribution of attenuation coefficients is stored in memory for efficient access during the projection and backprojection operations. The reconstruction of the source distribution is obtained by using a conjugate gradient or SIRT type iterative algorithm which requires one projection and one backprojection operation for each iteration. (author)

  3. Bulk viscosity and ultrasonic attenuation in liquid metals

    International Nuclear Information System (INIS)

    Awasthi, O.N.; Murthy, B.V.S.

    1984-11-01

    Ultrasonic attenuation in simple liquid metals has been investigated using the thermodynamic theory of relaxation processes incorporating the concept of a two state model for the liquid near the melting point. Agreement of the results with the experimental values of the ultrasonic attenuation and bulk viscosity indicates that this might be an appropriate approach to explain the excess attenuation of ultrasonic waves in liquid metals. (author)

  4. Mechanism of attenuation of a chimeric influenza A/B transfectant virus.

    Science.gov (United States)

    Luo, G; Bergmann, M; Garcia-Sastre, A; Palese, P

    1992-08-01

    The ribonucleoprotein transfection system for influenza virus allowed us to construct an influenza A virus containing a chimeric neuraminidase (NA) gene in which the noncoding sequence is derived from the NS gene of influenza B virus (T. Muster, E. K. Subbarao, M. Enami, B. P. Murphy, and P. Palese, Proc. Natl. Acad. Sci. USA 88:5177-5181, 1991). This transfectant virus is attenuated in mice and grows to lower titers in tissue culture than wild-type virus. Since such a virus has characteristics desirable for a live attenuated vaccine strain, attempts were made to characterize this virus at the molecular level. Our analysis suggests that the attenuation of the virus is due to changes in the cis signal sequences, which resulted in a reduction of transcription and replication of the chimeric NA gene. The major finding concerns a sixfold reduction in NA-specific viral RNA in the virion, causing a reduction in the ratio of infectious particles to physical particles compared with the ratio in wild-type virus. Although the NA-specific mRNA level is also reduced in transfectant virus-infected cells, it does not appear to contribute to the attenuation characteristics of the virus. The levels of the other RNAs and their expression appear to be unchanged for the transfectant virus. It is suggested that downregulation of the synthesis of one viral RNA segment leads to the generation of defective viruses during each replication cycle. We believe that this represents a general principle for attenuation which may be applied to other segmented viruses containing either single-stranded or double-stranded RNA.

  5. Performance evaluation of the spectral centroid downshift method for attenuation estimation.

    Science.gov (United States)

    Samimi, Kayvan; Varghese, Tomy

    2015-05-01

    Estimation of frequency-dependent ultrasonic attenuation is an important aspect of tissue characterization. Along with other acoustic parameters studied in quantitative ultrasound, the attenuation coefficient can be used to differentiate normal and pathological tissue. The spectral centroid downshift (CDS) method is one the most common frequencydomain approaches applied to this problem. In this study, a statistical analysis of this method's performance was carried out based on a parametric model of the signal power spectrum in the presence of electronic noise. The parametric model used for the power spectrum of received RF data assumes a Gaussian spectral profile for the transmit pulse, and incorporates effects of attenuation, windowing, and electronic noise. Spectral moments were calculated and used to estimate second-order centroid statistics. A theoretical expression for the variance of a maximum likelihood estimator of attenuation coefficient was derived in terms of the centroid statistics and other model parameters, such as transmit pulse center frequency and bandwidth, RF data window length, SNR, and number of regression points. Theoretically predicted estimation variances were compared with experimentally estimated variances on RF data sets from both computer-simulated and physical tissue-mimicking phantoms. Scan parameter ranges for this study were electronic SNR from 10 to 70 dB, transmit pulse standard deviation from 0.5 to 4.1 MHz, transmit pulse center frequency from 2 to 8 MHz, and data window length from 3 to 17 mm. Acceptable agreement was observed between theoretical predictions and experimentally estimated values with differences smaller than 0.05 dB/cm/MHz across the parameter ranges investigated. This model helps predict the best attenuation estimation variance achievable with the CDS method, in terms of said scan parameters.

  6. Self-attenuation factors in gamma-ray spectrometry

    International Nuclear Information System (INIS)

    Korun, M.

    1999-01-01

    The relation between the self-attenuation factors and the distribution function describing the number of photons detected in the full-energy peaks, as a function of their path length in the sample is presented. The relations between the self-attenuation factor and the moments of the distribution function, the average path length and the variance are also presented. The use of these relations is illustrated by applying them to self-attenuation factors describing attenuation in cylindrical samples. The results of the calculations are compared with the measured average path lengths and discussed in terms of the properties of the distribution function. (author)

  7. Compensation for nonuniform attenuation in SPECT brain imaging

    International Nuclear Information System (INIS)

    Glick, S.J.; King, M.A.; Pan, T.S.; Soares, E.J.

    1996-01-01

    Accurate compensation for photon attenuation is needed to perform quantitative brain single-photon-emission computed tomographic (SPECT) imaging. Bellini's attenuation-compensation method has been used with a nonuniform attenuation map to account for the nonuniform attenuation properties of the head. Simulation studies using a three-dimensional (3-D) digitized anthropomorphic brain phantom were conducted to compare quantitative accuracy of reconstructions obtained with the nonuniform Bellini method to that obtained with the Chang method and to iterative reconstruction using maximum-likelihood expectation maximization (ML-EM). Using the Chang method and assuming the head to be a uniform attenuator gave reconstructions with an average bias of approximately 6-8%, whereas using the Bellini or the iterative ML-EM method with a nonuniform attenuation map gave an average bias of approximately 1%. The computation time required to implement nonuniform attenuation compensation with the Bellini algorithm is approximately equivalent to the time required to perform one iteration of ML-EM. Thus, using the Bellini method with a nonuniform attenuation map provides accurate compensation for photon attenuation within the head, and the method can be implemented in computation times suitable for routine clinical use

  8. An Approximate Method for the Acoustic Attenuating VTI Eikonal Equation

    KAUST Repository

    Hao, Q.

    2017-05-26

    We present an approximate method to solve the acoustic eikonal equation for attenuating transversely isotropic media with a vertical symmetry axis (VTI). A perturbation method is used to derive the perturbation formula for complex-valued traveltimes. The application of Shanks transform further enhances the accuracy of approximation. We derive both analytical and numerical solutions to the acoustic eikonal equation. The analytic solution is valid for homogeneous VTI media with moderate anellipticity and strong attenuation and attenuation-anisotropy. The numerical solution is applicable for inhomogeneous attenuating VTI media.

  9. An Approximate Method for the Acoustic Attenuating VTI Eikonal Equation

    KAUST Repository

    Hao, Q.; Alkhalifah, Tariq Ali

    2017-01-01

    We present an approximate method to solve the acoustic eikonal equation for attenuating transversely isotropic media with a vertical symmetry axis (VTI). A perturbation method is used to derive the perturbation formula for complex-valued traveltimes. The application of Shanks transform further enhances the accuracy of approximation. We derive both analytical and numerical solutions to the acoustic eikonal equation. The analytic solution is valid for homogeneous VTI media with moderate anellipticity and strong attenuation and attenuation-anisotropy. The numerical solution is applicable for inhomogeneous attenuating VTI media.

  10. Attenuation of multiples in image space

    Science.gov (United States)

    Alvarez, Gabriel F.

    In complex subsurface areas, attenuation of 3D specular and diffracted multiples in data space is difficult and inaccurate. In those areas, image space is an attractive alternative. There are several reasons: (1) migration increases the signal-to-noise ratio of the data; (2) primaries are mapped to coherent events in Subsurface Offset Domain Common Image Gathers (SODCIGs) or Angle Domain Common Image Gathers (ADCIGs); (3) image space is regular and smaller; (4) attenuating the multiples in data space leaves holes in the frequency-Wavenumber space that generate artifacts after migration. I develop a new equation for the residual moveout of specular multiples in ADCIGs and use it for the kernel of an apex-shifted Radon transform to focus and separate the primaries from specular and diffracted multiples. Because of small amplitude, phase and kinematic errors in the multiple estimate, we need adaptive matching and subtraction to estimate the primaries. I pose this problem as an iterative least-squares inversion that simultaneously matches the estimates of primaries and multiples to the data. Standard methods match only the estimate of the multiples. I demonstrate with real and synthetic data that the method produces primaries and multiples with little cross-talk. In 3D, the multiples exhibit residual moveout in SODCIGs in in-line and cross-line offsets. They map away from zero subsurface offsets when migrated with the faster velocity of the primaries. In ADCIGs the residual moveout of the primaries as a function of the aperture angle, for a given azimuth, is flat for those angles that illuminate the reflector. The multiples have residual moveout towards increasing depth for increasing aperture angles at all azimuths. As a function of azimuth, the primaries have better azimuth resolution than the multiples at larger aperture angles. I show, with a real 3D dataset, that even below salt, where illumination is poor, the multiples are well attenuated in ADCIGs with the new

  11. Enhanced Attenuation Technologies: Passive Soil Vapor Extraction

    Energy Technology Data Exchange (ETDEWEB)

    Vangelas, K.; Looney, B.; Kamath, R.; Adamson, D.; Newell, C.

    2010-03-15

    Passive soil vapor extraction (PSVE) is an enhanced attenuation (EA) approach that removes volatile contaminants from soil. The extraction is driven by natural pressure gradients between the subsurface and atmosphere (Barometric Pumping), or by renewable sources of energy such as wind or solar power (Assisted PSVE). The technology is applicable for remediating sites with low levels of contamination and for transitioning sites from active source technologies such as active soil vapor extraction (ASVE) to natural attenuation. PSVE systems are simple to design and operate and are more cost effective than active systems in many scenarios. Thus, PSVE is often appropriate as an interim-remedial or polishing strategy. Over the past decade, PSVE has been demonstrated in the U.S. and in Europe. These demonstrations provide practical information to assist in selecting, designing and implementing the technology. These demonstrations indicate that the technology can be effective in achieving remedial objectives in a timely fashion. The keys to success include: (1) Application at sites where the residual source quantities, and associated fluxes to groundwater, are relatively low; (2) Selection of the appropriate passive energy source - barometric pumping in cases with a deep vadose zone and barrier (e.g., clay) layers that separate the subsurface from the atmosphere and renewable energy assisted PSVE in other settings and where higher flow rates are required. (3) Provision of sufficient access to the contaminated vadose zones through the spacing and number of extraction wells. This PSVE technology report provides a summary of the relevant technical background, real-world case study performance, key design and cost considerations, and a scenario-based cost evaluation. The key design and cost considerations are organized into a flowchart that dovetails with the Enhanced Attenuation: Chlorinated Organics Guidance of the Interstate Technology and Regulatory Council (ITRC). The PSVE

  12. Ultrasonic attenuation in rare-earth monoarsenides

    Indian Academy of Sciences (India)

    June 2016 physics pp. ... DOI: 10.1007/s12043-015-1183-5; ePublication: 17 March 2016. Abstract. ..... [10] R Ferro, Act. Crystallogr. 8, 360 (1955) ... [44] D E Gray, American Institute of Physics handbook (McGraw-Hill Book Company, Inc., New.

  13. Improved soil particle-size analysis by gamma-ray attenuation

    International Nuclear Information System (INIS)

    Oliveira, J.C.M.; Vaz, C.M.P.; Reichardt, K.; Swartzendruber, D.

    1997-01-01

    The size distribution of particles is useful for physical characterization of soil. This study was conducted to determine whether a new method of soil particle-size analysis by gamma-ray attenuation could be further improved by changing the depth and time of measurement of the suspended particle concentration during sedimentation. In addition to the advantage of nondestructive, undisturbed measurement by gamma-ray attenuation, as compared with conventional pipette or hydrometer methods, the modifications here suggested and employed do substantially decrease the total time for analysis, and will also facilitate total automation and generalize the method for other sedimentation studies. Experimental results are presented for three different Brazilian soil materials, and illustrate the nature of the fine detail provided in the cumulative particle-size distribution as given by measurements obtained during the relatively short time period of 28 min

  14. Snowpack snow water equivalent measurement using the attenuation of cosmic gamma radiation

    International Nuclear Information System (INIS)

    Osterhuber, R.; Condreva, K.

    1998-01-01

    Incoming, background cosmic radiation constantly fluxes through the earth's atmosphere. The high energy gamma portion of this radiation penetrates many terrestrial objects, including the winter snowpack. The attenuation of this radiation is exponentially related to the mass of the medium through which it penetrates. For the past three winters, a device measuring cosmic gamma radiation--and its attenuation through snow--has been installed at the Central Sierra Snow Laboratory, near Donner Pass, California. This gamma sensor, measuring energy levels between 5 and 15 MeV, has proved to be an accurate, reliable, non-invasive, non-mechanical instrument with which to measure the total snow water equivalent of a snowpack. This paper analyzes three winters' worth of data and discusses the physics and practical application of the sensor for the collection of snow water equivalent data from a remote location

  15. Attenuation and Dispersion in Earth's Materials

    Science.gov (United States)

    Gueguen, Y.

    2012-04-01

    One of the last challenges of Pr. Luigi Burlini has been to set up an experimental apparatus that would measure elastic wave attenuation under high pressure conditions. This project has since been developed by his colleagues and students at ETH. As a tribute to Luigi Burlini, this presentation aims at recalling why such measurements are important , how challenging such a project is, and what the main issues ahead are. Most of our knowledge about either crustal layers (seismic exploration) or deeper layers (seismology) results from data related to elastic wave propagation inside the Earth. The large amount of available data as well as the huge capability of computers are such that descriptions in terms of isotropic homogeneous layers appear to be very crude today. Anisotropic, heterogeneous models are reported at various scales. In addition, accounting for wave attenuation (the Q factor) is potentially of great interest. The Q factor is highly sensitive to processes that involve some departure from perfect elasticity. Its knowledge may provide information on possible fluid content, temperature, etc. This is because various processes may dissipate energy (and thus lower Q value) as a result of fluid flow, solid flow, etc., depending on the precise P-T conditions at depth. This points immediately to the theoretical challenge of Q investigations: there are many possible ways for a rock to not behave as a perfect elastic body. To model these various mechanisms and identify in which conditions they can take place is a first major challenge. The second challenge is on the experimental ground. What is looked for is to get low frequencies (f close to seismic frequencies) Q data on crustal (or mantle) rocks at high pressure P-high temperature T. Experiments in such highT-high P-low f conditions are extremely difficult to perform. Only in Canberra (I. Jackson) and now in Zurich such conditions have been achieved. Attenuation and dispersion (frequency dependence) of elastic

  16. Glutathione attenuates uranyl toxicity in Lactococcus lactis

    Energy Technology Data Exchange (ETDEWEB)

    Fahmy, Karim; Oertel, Jana [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Biophysics; Obeid, M. [Technische Univ. Dresden (Germany); Solioz, M. [Bern Univ. (Switzerland)

    2017-06-01

    We investigated the role of intracellular glutathione (GSH), which in a large number of taxa plays a role in the protection against the toxicity of heavy metals. Anaerobically grown Lactococcus lactis containing an inducible GSH synthesis pathway was used as a model organism allowing the study of GSH-dependent uranyl detoxification without interference from additional reactive oxygen species. Microcalorimetric measurements of the metabolic heat showed that intracellular GSH attenuates the toxicity of uranium at a concentration in the range of 10-150 μM. Isothermal titration calorimetry revealed the endothermic binding of U(VI) to the carboxyl group(s) of GSH. The data indicate that the primary detoxifying mechanism is the intracellular sequestration of carboxyl-coordinated U(VI) into an insoluble complex with GSH.

  17. Attenuation of thermal neutron through graphite

    International Nuclear Information System (INIS)

    Adib, M.; Ismaail, H.; Fathaallah, M.; Abbas, Y.; Habib, N.; Wahba, M.

    2004-01-01

    Calculation of the nuclear capture, thermal diffuse and Bragg scattering cross-sections as a function of graphite temperature and crystalline from for neutron energies from 1 me V< E<10 eV were carried out. Computer programs have been developed which allow calculation for the graphite hexagonal closed-pack structure in its polycrystalline form and pyrolytic one. I The calculated total cross-section for polycrystalline graphite were compared with the experimental values. An overall agreement is indicated between the calculated values and experimental ones. Agreement was also obtained for neutron cross-section measured for oriented pyrolytic graphite at room and liquid nitrogen temperatures. A feasibility study for use of graphite in powdered form as a cold neutron filter is details. The calculated attenuation of thermal neutrons through large mosaic pyrolytic graphite show that such crystals can be used effectively as second order filter of thermal neutron beams and that cooling improve their effectiveness

  18. Glutathione attenuates uranyl toxicity in Lactococcus lactis

    International Nuclear Information System (INIS)

    Fahmy, Karim; Oertel, Jana; Solioz, M.

    2017-01-01

    We investigated the role of intracellular glutathione (GSH), which in a large number of taxa plays a role in the protection against the toxicity of heavy metals. Anaerobically grown Lactococcus lactis containing an inducible GSH synthesis pathway was used as a model organism allowing the study of GSH-dependent uranyl detoxification without interference from additional reactive oxygen species. Microcalorimetric measurements of the metabolic heat showed that intracellular GSH attenuates the toxicity of uranium at a concentration in the range of 10-150 μM. Isothermal titration calorimetry revealed the endothermic binding of U(VI) to the carboxyl group(s) of GSH. The data indicate that the primary detoxifying mechanism is the intracellular sequestration of carboxyl-coordinated U(VI) into an insoluble complex with GSH.

  19. Release and attenuation of fluorocarbons in landfills

    DEFF Research Database (Denmark)

    Kjeldsen, Peter; Scheutz, Charlotte

    2003-01-01

    Several halocarbons with very high global warming and ozone depleting potentials have been used as blowing agent for insulation foam in refrigerators and freezers. Many appliances are shredded after the end of their useful life. Release experiments carried out in the laboratory on insulation foam...... blown with CFC-11, HCFC-141b, HFC- 134a, and HFC-245fa revealed that most of the blowing agent is not released to the atmosphere during a six-week period following the shredding process. The fraction which is released in the six-week period is highly dependent on how fine the foam is shredded....... The residual blowing agent remaining after the six-week period may be very slowly released if the integrity of the foam particles with respect to diffusional properties is kept after disposal of the foam waste in landfills. Laboratory experiments simulating attenuation processes in the landfilled waste...

  20. Core disgust is attenuated by ingroup relations.

    Science.gov (United States)

    Reicher, Stephen D; Templeton, Anne; Neville, Fergus; Ferrari, Lucienne; Drury, John

    2016-03-08

    We present the first experimental evidence to our knowledge that ingroup relations attenuate core disgust and that this helps explain the ability of groups to coact. In study 1, 45 student participants smelled a sweaty t-shirt bearing the logo of another university, with either their student identity (ingroup condition), their specific university identity (outgroup condition), or their personal identity (interpersonal condition) made salient. Self-reported disgust was lower in the ingroup condition than in the other conditions, and disgust mediated the relationship between condition and willingness to interact with target. In study 2, 90 student participants smelled a sweaty target t-shirt bearing either the logo of their own university, another university, or no logo, with either their student identity or their specific university identity made salient. Walking time to wash hands and pumps of soap indicated that disgust was lower where the relationship between participant and target was ingroup rather than outgroup or ambivalent (no logo).

  1. Attenuation of species abundance distributions by sampling

    Science.gov (United States)

    Shimadzu, Hideyasu; Darnell, Ross

    2015-01-01

    Quantifying biodiversity aspects such as species presence/ absence, richness and abundance is an important challenge to answer scientific and resource management questions. In practice, biodiversity can only be assessed from biological material taken by surveys, a difficult task given limited time and resources. A type of random sampling, or often called sub-sampling, is a commonly used technique to reduce the amount of time and effort for investigating large quantities of biological samples. However, it is not immediately clear how (sub-)sampling affects the estimate of biodiversity aspects from a quantitative perspective. This paper specifies the effect of (sub-)sampling as attenuation of the species abundance distribution (SAD), and articulates how the sampling bias is induced to the SAD by random sampling. The framework presented also reveals some confusion in previous theoretical studies. PMID:26064626

  2. LIVE ATTENUATED VACCINES FOR THE IMMUNOPROPHYLAXIS

    Directory of Open Access Journals (Sweden)

    O. A. Shamsutdinova

    2017-01-01

    Full Text Available The review focuses on the history of the production of live antiviral vaccines and their use for the prevention of infectious diseases. It was noted that before the beginning of the 20th century, only three live vaccines were developed and put into practice — against smallpox, rabies, plague. The discovery of D. Enders, T.H. Weller and F.Ch. Robins of the ability of the polio virus, and then of a number of other viruses, to reproduce in vitro in cell cultures of various types, greatly expanded the studies on the production of attenuated strains of viruses for live vaccines. The historical stages of obtaining and introducing live vaccines for the prevention of smallpox, poliomyelitis, measles, rubella, and mumps are highlighted. Arguments in favor of the use of associated vaccine preparations for the prevention of viral infections are presented. Various variants of the strategy and tactics of using live vaccines, which are used for specific prevention of viral infections in different countries, are described. The review provides information on technological methods for obtaining antiviral vaccines. The publications testifying to the development of specific reactions in immunized vaccine strains of measles, mumps, poliomyelitis and rubella viruses, such as aseptic meningitis (vaccine strains of mumps virus, acute arthritis (vaccine rubella virus strains, temperature reactions, rash (vaccine strains of the virus Measles, vaccine-associated paralytic poliomyelitis (VAPP vaccine vaccine poliovirus. It is particularly noted that the long experience of vaccine prevention both in Russia and abroad convincingly shows that the risk of developing post-vaccination complications is incommensurably lower than the risk of causing harm to health from the corresponding infections. It is concluded that despite introduction of new third and fourth generation vaccines into practice, live attenuated vaccines do not lose their significance and are used in vaccine

  3. Engineering a Light-Attenuating Artificial Iris

    Science.gov (United States)

    Shareef, Farah J.; Sun, Shan; Kotecha, Mrignayani; Kassem, Iris; Azar, Dimitri; Cho, Michael

    2016-01-01

    Purpose Discomfort from light exposure leads to photophobia, glare, and poor vision in patients with congenital or trauma-induced iris damage. Commercial artificial iris lenses are static in nature to provide aesthetics without restoring the natural iris's dynamic response to light. A new photo-responsive artificial iris was therefore developed using a photochromic material with self-adaptive light transmission properties and encased in a transparent biocompatible polymer matrix. Methods The implantable artificial iris was designed and engineered using Photopia, a class of photo-responsive materials (termed naphthopyrans) embedded in polyethylene. Photopia was reshaped into annular disks that were spin-coated with polydimethylsiloxane (PDMS) to form our artificial iris lens of controlled thickness. Results Activated by UV and blue light in approximately 5 seconds with complete reversal in less than 1 minute, the artificial iris demonstrates graded attenuation of up to 40% of visible and 60% of UV light. There optical characteristics are suitable to reversibly regulate the incident light intensity. In vitro cell culture experiments showed up to 60% cell death within 10 days of exposure to Photopia, but no significant cell death observed when cultured with the artificial iris with protective encapsulation. Nuclear magnetic resonance spectroscopy confirmed these results as there was no apparent leakage of potentially toxic photochromic material from the ophthalmic device. Conclusions Our artificial iris lens mimics the functionality of the natural iris by attenuating light intensity entering the eye with its rapid reversible change in opacity and thus potentially providing an improved treatment option for patients with iris damage. PMID:27116547

  4. Fitness attenuates the prevalence of increased coronary artery calcium in individuals with metabolic syndrome.

    Science.gov (United States)

    Ekblom-Bak, Elin; Ekblom, Örjan; Fagman, Erika; Angerås, Oskar; Schmidt, Caroline; Rosengren, Annika; Börjesson, Mats; Bergström, Göran

    2018-02-01

    Background The association between cardiorespiratory fitness, physical activity and coronary artery calcium (CAC) is unclear, and whether higher levels of fitness attenuate CAC prevalence in subjects with metabolic syndrome is not fully elucidated. The present study aims to: a) investigate the independent association of fitness on the prevalence of CAC, after adjustment for moderate-to-vigorous physical activity and sedentary time, and b) study the possible attenuation of increased CAC by higher fitness, in participants with metabolic syndrome. Design Cross-sectional. Methods In total 678 participants (52% women), 50-65 years old, from the SCAPIS pilot study were included. Fitness (VO 2 max) was estimated by submaximal cycle ergometer test and moderate-to-vigorous physical activity and sedentary time were assessed using hip-worn accelerometers. CAC score (CACS) was quantified using the Agatston score. Results The odds of having a significant CACS (≥100) was half in participants with moderate/high fitness compared with their low fitness counterparts. Further consideration of moderate-to-vigorous physical activity, sedentary time and number of components of the metabolic syndrome did only slightly alter the effect size. Those with metabolic syndrome had 47% higher odds for significant CAC compared with those without metabolic syndrome. However, moderate/high fitness seems to partially attenuate this risk, as further joint analysis indicated an increased odds for having significant CAC only in the unfit metabolic syndrome participants. Conclusions Being fit is associated with a reduced risk of having significant CAC in individuals with metabolic syndrome. While still very much underutilized, fitness should be taken into consideration in everyday clinical risk prediction in addition to the traditional risk factors of the metabolic syndrome.

  5. Sports physical

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000673.htm Sports physical To use the sharing features on this page, ... routine checkups. Why do you Need a Sports Physical? The sports physical is done to: Find out ...

  6. Physical Allergy

    Science.gov (United States)

    ... Autologous Stem Cell Transplant Additional Content Medical News Physical Allergy By Peter J. Delves, PhD, Professor of ... Disorders Exercise-Induced Allergic Reactions Food Allergy Mastocytosis Physical Allergy Seasonal Allergies Year-Round Allergies A physical ...

  7. Sports Physicals

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Sports Physicals KidsHealth / For Teens / Sports Physicals What's in ... beginning of your sports season. What Is a Sports Physical? In the sports medicine field, the sports ...

  8. A miniaturized reconfigurable broadband attenuator based on RF MEMS switches

    International Nuclear Information System (INIS)

    Guo, Xin; Gong, Zhuhao; Zhong, Qi; Liang, Xiaotong; Liu, Zewen

    2016-01-01

    Reconfigurable attenuators are widely used in microwave measurement instruments. Development of miniaturized attenuation devices with high precision and broadband performance is required for state-of-the-art applications. In this paper, a compact 3-bit microwave attenuator based on radio frequency micro-electro-mechanical system (RF MEMS) switches and polysilicon attenuation modules is presented. The device comprises 12 ohmic contact MEMS switches, π -type polysilicon resistive attenuation modules and microwave compensate structures. Special attention was paid to the design of the resistive network, compensate structures and system simulation. The device was fabricated using micromachining processes compatible with traditional integrated circuit fabrication processes. The reconfigurable attenuator integrated with RF MEMS switches and resistive attenuation modules was successfully fabricated with dimensions of 2.45  ×  4.34  ×  0.5 mm 3 , which is 1/1000th of the size of a conventional step attenuator. The measured RF performance revealed that the attenuator provides 10–70 dB attenuation at 10 dB intervals from 0.1–20 GHz with an accuracy better than  ±1.88 dB at 60 dB and an error of less than 2.22 dB at 10 dB. The return loss of each state of the 3-bit attenuator was better than 11.95 dB (VSWR  <  1.71) over the entire operating band. (paper)

  9. Use of calibration standards and the correction for sample self-attenuation in gamma-ray nondestructive assay

    International Nuclear Information System (INIS)

    Parker, J.L.

    1984-08-01

    The efficient use of appropriate calibration standards and the correction for the attenuation of the gamma rays within an assay sample by the sample itself are two important and closely related subjects in gamma-ray nondestructive assay. Much research relating to those subjects has been done in the Nuclear Safeguards Research and Development program at the Los Alamos National Laboratory since 1970. This report brings together most of the significant results of that research. Also discussed are the nature of appropriate calibration standards and the necessary conditions on the composition, size, and shape of the samples to allow accurate assays. Procedures for determining the correction for the sample self-attenuation are described at length including both general principles and several specific useful cases. The most useful concept is that knowing the linear attenuation coefficient of the sample (which can usually be determined) and the size and shape of the sample and its position relative to the detector permits the computation of the correction factor for the self-attenuation. A major objective of the report is to explain how the procedures for determining the self-attenuation correction factor can be applied so that calibration standards can be entirely appropriate without being particularly similar, either physically or chemically, to the items to be assayed. This permits minimization of the number of standards required to assay items with a wide range of size, shape, and chemical composition. 17 references, 18 figures, 2 tables

  10. The use of calibration standards and the correction for sample self-attenuation in gamma-ray nondestructive assay

    International Nuclear Information System (INIS)

    Parker, J.L.

    1986-11-01

    The efficient use of appropriate calibration standards and the correction for the attenuation of the gamma rays within an assay sample by the sample itself are two important and closely related subjects in gamma-ray nondestructive assay. Much research relating to those subjects has been done in the Nuclear Safeguards Research and Development program at the Los Alamos National Laboratory since 1970. This report brings together most of the significant results of that research. Also discussed are the nature of appropriate calibration standards and the necessary conditions on the composition, size, and shape of the samples to allow accurate assays. Procedures for determining the correction for the sample self-attenuation are described at length including both general principles and several specific useful cases. The most useful concept is that knowing the linear attenuation coefficient of the sample (which can usually be determined) and the size and shape of the sample and its position relative to the detector permits the computation of the correction factor for the self-attenuation. A major objective of the report is to explain how the procedures for determining the self-attenuation correction factor can be applied so that calibration standards can be entirely appropriate without being particularly similar, either physically or chemically, to the items to be assayed. This permits minimization of the number of standards required to assay items with a wide range of size, shape, and chemical composition

  11. Obtaining the mass attenuation coefficient of the wood to a beam of gamma-ray of 241Am

    International Nuclear Information System (INIS)

    Costa, Vladimir Eliodoro; Rezende, Marcos Antonio de

    2009-01-01

    Full text: The quality of wood produced in Brazil reforestation has been the subject of many discussions in the Forestry Sector. SeEKXing to produce a rapid growth and wood quality, the Forestry Sector, found in Applied Nuclear Physics, a precise method of determining the density of wood known as ad hoc technique of attenuation of gamma-ray. The radioisotope used in this technique is that it has a picture 241 Am peak of 59.6 keV gamma-ray. This work has the objective of determining the mass attenuation coefficient of wood of the genus Eucalyptus for 241 Am radioisotope. We used 324 samples of wood from six different treatments: a seminal of Eucalyptus grandis; two clones of E. grandis; three clones of the hybrid E. grandis x E. urophylla. The same assay was used for the six treatments. It was determined the basic density of the samples by the method of immersion in water and then the basic density was converted into apparent density in the moisture equilibrium and it was determined the attenuation coefficient of mass. Preliminary results showed that the attenuation coefficient of mass did not vary between treatments, and its average value 0.1822 ± 0.0015. It was to here that the attenuation coefficient of mass in the wood of the genus Eucalyptus in moisture equilibrium can be constant. (author)

  12. The Self Attenuation Correction for Holdup Measurements, a Historical Perspective

    International Nuclear Information System (INIS)

    Oberer, R. B.; Gunn, C. A.; Chiang, L. G.

    2006-01-01

    Self attenuation has historically caused both conceptual as well as measurement problems. The purpose of this paper is to eliminate some of the historical confusion by reviewing the mathematical basis and by comparing several methods of correcting for self attenuation focusing on transmission as a central concept

  13. When and Why Mimicry is Facilitated and Attenuated

    NARCIS (Netherlands)

    Stel, Mariëlle; van Dijk, Eric; van Baaren, Rick B.

    2016-01-01

    Although people tend to mimic others automatically, mimicry is facilitated or attenuated depending on the specific context. In the current paper, the authors discuss when mimicry is facilitated and attenuated depending on characteristics of situations, targets, and observers. On the basis of the

  14. Developement of a Light Attenuator Based on Glassy Reflections ...

    African Journals Online (AJOL)

    The light intensity control of a luminous source is a very important operation in many optical applications. Several types of light attenuator exploiting different optical phenomena like diffraction, absorption, and reflection exist and they differ principally in the maximum attenuation rate, the control range, the sensitivity and the ...

  15. Statistical problems with weather-radar images, II: Attenuation detection

    International Nuclear Information System (INIS)

    Fernandez-Duran, Juan-Jose; Upton, Graham

    2003-01-01

    A procedure based on the combination of a Bayesian changepoint model and ordinary least squares is used to identify and quantify regions where a radar signal has been attenuated (i.e.diminished) as a consequence of intervening weather. A graphical polar display is introduced that illustrates the location and importance of the attenuation

  16. Attenuated radon transform: theory and application in medicine and biology

    Energy Technology Data Exchange (ETDEWEB)

    Gullberg, G.T.

    1979-06-01

    A detailed analysis is given of the properties of the attenuated Radon transform and of how increases in photon attenuation influence the numerical accuracy and computation efficiency of iterative and convolution algorithms used to determine its inversion. The practical applications for this work involve quantitative assessment of the distribution of injected radiopharmaceuticals and radionuclides in man and animals for basic physiological and biochemical studies as well as clinical studies in nuclear medicine. A mathematical structure is developed using function theory and the theory of linear operators on Hilbert spaces which lends itself to better understanding the spectral properties of the attenuated Radon transform. The continuous attenuated Radon transform reduces to a matrix operator for discrete angular and lateral sampling, and the reconstruction problem reduces to a system of linear equations. For the situation of variable attenuation coefficient frequently found in nuclear medicine applications of imaging the heart and chest, the procedure developed in this thesis involves iterative techniques of performing the generalized inverse. For constant attenuation coefficient less than 0.15 cm/sup -1/, convolution methods can reliably reconstruct a 30 cm object with 0.5 cm resolution. However, for high attenuation coefficients or for the situation where there is variable attenuation such as reconstruction of distribution of isotopes in the heart, iterative techniques developed in this thesis give the best results. (ERB)

  17. An attenuation measurement technique for rotating planar detector positron tomographs

    International Nuclear Information System (INIS)

    McNeil, P.A.; Julyan, P.J.; Parker, D.J.

    1997-01-01

    This paper presents a new attenuation measurement technique suitable for rotating planar detector positron tomographs. Transmission measurements are made using two unshielded positron-emitting line sources, one attached to the front face of each detector. Many of the scattered and accidental coincidences are rejected by including only those coincidences that form a vector passing within a predetermined distance of either line source. Some scattered and accidental coincidences are still included, which reduces the measured linear attenuation; in principle their contribution can be accurately estimated and subtracted, but in practice, when limited statistics are available (as is the case with the multi-wire Birmingham positron camera), this background subtraction unacceptably increases the noise. Instead an attenuation image having the correct features can be reconstructed from the measured projections. For objects containing only a few discrete linear attenuation coefficients, segmentation of this attenuation image reduces noise and allows the correct linear attenuation coefficients to be restored by renormalization. Reprojection through the segmented image may then provide quantitatively correct attenuation correction factors of sufficient statistical quality to correct for attenuation in PET emission images. (author)

  18. Lattice Boltzmann simulations of attenuation-driven acoustic streaming

    International Nuclear Information System (INIS)

    Haydock, David; Yeomans, J M

    2003-01-01

    We show that lattice Boltzmann simulations can be used to model the attenuation-driven acoustic streaming produced by a travelling wave. Comparisons are made to analytical results and to the streaming pattern produced by an imposed body force approximating the Reynolds stresses. We predict the streaming patterns around a porous material in an attenuating acoustic field

  19. Pramana – Journal of Physics | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics. N Ramachandran. Articles written in Pramana – Journal of Physics. Volume 67 Issue 3 September 2006 pp 501-506 Research Articles. Simulated mixed absorbers and effective atomic numbers for attenuation · K Karunakaran Nair N Ramachandran K K Abdullah K M Varier.

  20. Pramana – Journal of Physics | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics. K K Abdullah. Articles written in Pramana – Journal of Physics. Volume 67 Issue 3 September 2006 pp 501-506 Research Articles. Simulated mixed absorbers and effective atomic numbers for attenuation · K Karunakaran Nair N Ramachandran K K Abdullah K M Varier.

  1. Attenuation correction for the NIH ATLAS small animal PET scanner

    CERN Document Server

    Yao, Rutao; Liow, JeihSan; Seidel, Jurgen

    2003-01-01

    We evaluated two methods of attenuation correction for the NIH ATLAS small animal PET scanner: 1) a CT-based method that derives 511 keV attenuation coefficients (mu) by extrapolation from spatially registered CT images; and 2) an analytic method based on the body outline of emission images and an empirical mu. A specially fabricated attenuation calibration phantom with cylindrical inserts that mimic different body tissues was used to derive the relationship to convert CT values to (I for PET. The methods were applied to three test data sets: 1) a uniform cylinder phantom, 2) the attenuation calibration phantom, and 3) a mouse injected with left bracket **1**8F right bracket FDG. The CT-based attenuation correction factors were larger in non-uniform regions of the imaging subject, e.g. mouse head, than the analytic method. The two methods had similar correction factors for regions with uniform density and detectable emission source distributions.

  2. Introduction to radiological physics and radiation dosimetry

    CERN Document Server

    Attix, Frank Herbert

    2004-01-01

    A straightforward presentation of the broad concepts underlying radiological physics and radiation dosimetry for the graduate-level student. Covers photon and neutron attenuation, radiation and charged particle equilibrium, interactions of photons and charged particles with matter, radiotherapy dosimetry, as well as photographic, calorimetric, chemical, and thermoluminescence dosimetry. Includes many new derivations, such as Kramers X-ray spectrum, as well as topics that have not been thoroughly analyzed in other texts, such as broad-beam attenuation and geometrics, and the reciprocity theorem

  3. Attenuation of earmuffs used simultaneously with respiratory protective devices

    Directory of Open Access Journals (Sweden)

    Emil Kozłowski

    2017-06-01

    Full Text Available Background: In the work environment, apart from the noise, employees may be exposed to other harmful factors. Therefore, they wear hearing protectors and other personal protective equipment. The aim of the study was to determine whether simultaneous use of earmuffs and respiratory protective devices affects the attenuation of earmuffs. Material and Methods: The study was conducted in laboratory conditions using the subjective REAT (Real Ear Attenuation at Threshold and objective MIRE (Microphone in Real Ear methods. The REAT method was used to measure sound attenuation of earmuffs, while MIRE was used to determine changes in attenuation of earmuffs due to the use of other personal protective equipment. Results: The study showed reduction in attenuation of earmuffs due to the use of a full face mask up to 20 dB. Using a full face mask causes that attenuation of earmuffs in the low frequency range is close to zero. Reduction in attenuation due to the use of half masks for complete with particle filters (half masks is 3–15 dB. Simultaneous use of earmuffs and filtering half masks makes small changes in attenuation not exceeding 3 dB. Conclusions: The study showed that full face masks give the greatest reduction in attenuation of earmuffs. On the other hand, the least reduction is observed in the case of filtering half masks. There is a significant difference between the reduction in attenuation of earmuffs worn with half masks for complete with particle filters because they may be equipped with different kind of the head strap. Med Pr 2017;68(3:349–361

  4. Determination of mass attenuation coefficient in wood and leaves of typical trees by gamma-ray attenuation technique

    International Nuclear Information System (INIS)

    Miranda, Regina M. de; Pascholati, Elisabete M.

    1997-01-01

    Using an 241 Am source the mass attenuation coefficient of different woods and leaves of typical species of the Atlantic Forest were measured. The results for natural wood, dry wood and dry leaves indicate that the variation is very small among different species. However, woods present a higher attenuation than leaves, both depending on their water content. (author). 10 refs., 3 figs., 1 tab

  5. Physical protection

    International Nuclear Information System (INIS)

    Myers, D.A.

    1989-01-01

    Physical protection is defined and its function in relation to other functions of a State System of Accounting for and Control of Nuclear Materials is described. The need for a uniform minimum international standard for physical protection as well as the need for international cooperation in physical protection is emphasized. The IAEA's INFCIRC/225/Rev. 1 (Annex 1) is reviewed. The Convention on the Physical Protection of Nuclear Material (Annex 2) is discussed. Photographs show examples of typical physical protection technology (Annex 3)

  6. A Role for Exercise in Attenuating Unhealthy Food Consumption in Response to Stress

    Directory of Open Access Journals (Sweden)

    Shina Leow

    2018-02-01

    Full Text Available It is well established that both acute and chronic stress can be detrimental to health and wellbeing by directly increasing the risk of several chronic diseases and related health problems. In addition, stress may contribute to ill-health indirectly via its downstream effects on individuals’ health-related behaviour, such as promoting the intake of unhealthy palatable foods high in fat and sugar content. This paper reviews (a the research literature on stress-models; (b recent research investigating stress-induced eating and (c the potential physiological and psychological pathways contributing to stress-induced eating. Particular attention is given to (d the role of physical exercise in attenuating acute stress, with exploration of potential mechanisms through which exercise may reduce unhealthy food and drink consumption subsequent to stressor exposure. Finally, exercise motivation is discussed as an important psychological influence over the capacity for physical exercise to attenuate unhealthy food and drink consumption after exposure to stressors. This paper aims to provide a better understanding of how physical exercise might alleviate stress-induced unhealthy food choices.

  7. A Role for Exercise in Attenuating Unhealthy Food Consumption in Response to Stress.

    Science.gov (United States)

    Leow, Shina; Jackson, Ben; Alderson, Jacqueline A; Guelfi, Kym J; Dimmock, James A

    2018-02-06

    It is well established that both acute and chronic stress can be detrimental to health and wellbeing by directly increasing the risk of several chronic diseases and related health problems. In addition, stress may contribute to ill-health indirectly via its downstream effects on individuals' health-related behaviour, such as promoting the intake of unhealthy palatable foods high in fat and sugar content. This paper reviews (a) the research literature on stress-models; (b) recent research investigating stress-induced eating and (c) the potential physiological and psychological pathways contributing to stress-induced eating. Particular attention is given to (d) the role of physical exercise in attenuating acute stress, with exploration of potential mechanisms through which exercise may reduce unhealthy food and drink consumption subsequent to stressor exposure. Finally, exercise motivation is discussed as an important psychological influence over the capacity for physical exercise to attenuate unhealthy food and drink consumption after exposure to stressors. This paper aims to provide a better understanding of how physical exercise might alleviate stress-induced unhealthy food choices.

  8. Application of the gamma-ray attenuation technique to forest sciences in Brazil

    International Nuclear Information System (INIS)

    Rezende, Marcos Antonio de; Costa, Vladimir Eliodoro; Bruder, Edson Marcelo

    2005-01-01

    The study of the physical characteristics of wood is fundamental to its correct utilization by the industry and to an efficient exploitation of this raw material. The most important characteristics of wood are the specific gravity, the shrinkage and the porosity. Those traits are related one to each other and to mechanic resistance and hygroscopicity. The present work proposes the utilization of the gamma-ray attenuation technique, through a sealed source of the radioisotope 241 Am with an activity of 7.4 GBq and an energy of 60 keV, to the determination of physical characteristics of the wood of Pinus tecunumannii, Liquidambar styraciflua and Eucalyptus grandis from cultivated fields of Duratex S/A, in Agudos, Sao Paulo State, Brazil. This work presents the advantages and the facilities of the utilization of this technique in the qualitative and quantitative study of the wood from reforestation fields. This technique is employed to determine the specific gravity of a material through the attenuation of gamma-ray after crossing a sample of uniform thickness. Results revealed superior quality of wood to the species L. styraciflua, followed by E. grandis. Considerable variation in the physical properties of the sample of P. tecunumannii was observed along the radial sense, indicating that this species is highly responsive to climatic factors. The more uniform wood of E. grandis and L. styraciflua suggest that these species may be more adapted to the climatic conditions of the Sao Paulo State than P. tecunumannii. (author)

  9. Endogenous cueing attenuates object substitution masking.

    Science.gov (United States)

    Germeys, Filip; Pomianowska, I; De Graef, P; Zaenen, P; Verfaillie, K

    2010-07-01

    Object substitution masking (OSM) is a form of visual masking in which a briefly presented target surrounded by four small dots is masked by the continuing presence of the four dots after target offset. A major parameter in the prediction of OSM is the time required for attention to be directed to the target following its onset. Object substitution theory (Di Lollo et al. in J Exp Psychol Gen 129:481-507, 2000) predicts that the sooner attention can be focused at the target's location, the less masking will ensue. However, recently Luiga and Bachmann (Psychol Res 71:634-640, 2007) presented evidence that precueing of attention to the target location prior to target-plus-mask onset by means of a central (endogenous) arrow cue does not reduce OSM. When attention was cued exogenously, OSM was attenuated. Based on these results, Luiga and Bachmann argued that object substitution theory should be adapted by differentiating the ways of directing attention to the target location. The goal of the present study was to further examine the dissociation between the effects of endogenous and exogenous precueing on OSM. Contrary to Luiga and Bachmann, our results show that prior shifts of attention to the target location initiated by both exogenous and endogenous cues reduce OSM as predicted by object substitution theory and its computational model CMOS.

  10. Silibinin attenuates allergic airway inflammation in mice

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yun Ho [Department of Anatomy, Medical School, Institute for Medical Sciences, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Jin, Guang Yu [Department of Radiology, Yanbian University Hospital, YanJi 133002 (China); Guo, Hui Shu [Centralab, The First Affiliated Hospital of Dalian Medical University, Dalian 116011 (China); Piao, Hong Mei [Department of Respiratory Medicine, Yanbian University Hospital, YanJi 133000 (China); Li, Liang chang; Li, Guang Zhao [Department of Anatomy and Histology and Embryology, Yanbian University School of Basic Medical Sciences, 977 Gongyuan Road, YanJi 133002, Jilin (China); Lin, Zhen Hua [Department of Pathology, Yanbian University School of Basic Medical Sciences, YanJi 133000 (China); Yan, Guang Hai, E-mail: ghyan@ybu.edu.cn [Department of Anatomy and Histology and Embryology, Yanbian University School of Basic Medical Sciences, 977 Gongyuan Road, YanJi 133002, Jilin (China)

    2012-10-26

    Highlights: Black-Right-Pointing-Pointer Silibinin diminishes ovalbumin-induced inflammatory reactions in the mouse lung. Black-Right-Pointing-Pointer Silibinin reduces the levels of various cytokines into the lung of allergic mice. Black-Right-Pointing-Pointer Silibinin prevents the development of airway hyperresponsiveness in allergic mice. Black-Right-Pointing-Pointer Silibinin suppresses NF-{kappa}B transcriptional activity. -- Abstract: Allergic asthma is a chronic inflammatory disease regulated by coordination of T-helper2 (Th2) type cytokines and inflammatory signal molecules. Silibinin is one of the main flavonoids produced by milk thistle, which is reported to inhibit the inflammatory response by suppressing the nuclear factor-kappa B (NF-{kappa}B) pathway. Because NF-{kappa}B activation plays a pivotal role in the pathogenesis of allergic inflammation, we have investigated the effect of silibinin on a mouse ovalbumin (OVA)-induced asthma model. Airway hyperresponsiveness, cytokines levels, and eosinophilic infiltration were analyzed in bronchoalveolar lavage fluid and lung tissue. Pretreatment of silibinin significantly inhibited airway inflammatory cell recruitment and peribronchiolar inflammation and reduced the production of various cytokines in bronchoalveolar fluid. In addition, silibinin prevented the development of airway hyperresponsiveness and attenuated the OVA challenge-induced NF-{kappa}B activation. These findings indicate that silibinin protects against OVA-induced airway inflammation, at least in part via downregulation of NF-{kappa}B activity. Our data support the utility of silibinin as a potential medicine for the treatment of asthma.

  11. Silibinin attenuates allergic airway inflammation in mice

    International Nuclear Information System (INIS)

    Choi, Yun Ho; Jin, Guang Yu; Guo, Hui Shu; Piao, Hong Mei; Li, Liang chang; Li, Guang Zhao; Lin, Zhen Hua; Yan, Guang Hai

    2012-01-01

    Highlights: ► Silibinin diminishes ovalbumin-induced inflammatory reactions in the mouse lung. ► Silibinin reduces the levels of various cytokines into the lung of allergic mice. ► Silibinin prevents the development of airway hyperresponsiveness in allergic mice. ► Silibinin suppresses NF-κB transcriptional activity. -- Abstract: Allergic asthma is a chronic inflammatory disease regulated by coordination of T-helper2 (Th2) type cytokines and inflammatory signal molecules. Silibinin is one of the main flavonoids produced by milk thistle, which is reported to inhibit the inflammatory response by suppressing the nuclear factor-kappa B (NF-κB) pathway. Because NF-κB activation plays a pivotal role in the pathogenesis of allergic inflammation, we have investigated the effect of silibinin on a mouse ovalbumin (OVA)-induced asthma model. Airway hyperresponsiveness, cytokines levels, and eosinophilic infiltration were analyzed in bronchoalveolar lavage fluid and lung tissue. Pretreatment of silibinin significantly inhibited airway inflammatory cell recruitment and peribronchiolar inflammation and reduced the production of various cytokines in bronchoalveolar fluid. In addition, silibinin prevented the development of airway hyperresponsiveness and attenuated the OVA challenge-induced NF-κB activation. These findings indicate that silibinin protects against OVA-induced airway inflammation, at least in part via downregulation of NF-κB activity. Our data support the utility of silibinin as a potential medicine for the treatment of asthma.

  12. Ursodeoxycholic acid attenuates colonic epithelial secretory function

    Science.gov (United States)

    Kelly, Orlaith B; Mroz, Magdalena S; Ward, Joseph B J; Colliva, Carolina; Scharl, Michael; Pellicciari, Roberto; Gilmer, John F; Fallon, Padraic G; Hofmann, Alan F; Roda, Aldo; Murray, Frank E; Keely, Stephen J

    2013-01-01

    Dihydroxy bile acids, such as chenodeoxycholic acid (CDCA), are well known to promote colonic fluid and electrolyte secretion, thereby causing diarrhoea associated with bile acid malabsorption. However, CDCA is rapidly metabolised by colonic bacteria to ursodeoxycholic acid (UDCA), the effects of which on epithelial transport are poorly characterised. Here, we investigated the role of UDCA in the regulation of colonic epithelial secretion. Cl− secretion was measured across voltage-clamped monolayers of T84 cells and muscle-stripped sections of mouse or human colon. Cell surface biotinylation was used to assess abundance/surface expression of transport proteins. Acute (15 min) treatment of T84 cells with bilateral UDCA attenuated Cl− secretory responses to the Ca2+ and cAMP-dependent secretagogues carbachol (CCh) and forskolin (FSK) to 14.0 ± 3.8 and 40.2 ± 7.4% of controls, respectively (n= 18, P acid (LCA). Accordingly, LCA (50–200 μm) enhanced agonist-induced secretory responses in vitro and a metabolically stable UDCA analogue, 6α-methyl-UDCA, exerted anti-secretory actions in vitro and in vivo. In conclusion, UDCA exerts direct anti-secretory actions on colonic epithelial cells and metabolically stable derivatives of the bile acid may offer a new approach for treating intestinal diseases associated with diarrhoea. PMID:23507881

  13. Assessment of satellite derived diffuse attenuation coefficients ...

    Science.gov (United States)

    Optical data collected in coastal waters off South Florida and in the Caribbean Sea between January 2009 and December 2010 were used to evaluate products derived with three bio-optical inversion algorithms applied to MOIDS/Aqua, MODIS/Terra, and SeaWiFS satellite observations. The products included the diffuse attenuation coefficient at 490 nm (Kd_490) and for the visible range (Kd_PAR), and euphotic depth (Zeu, corresponding to 1% of the surface incident photosynthetically available radiation or PAR). Above-water hyperspectral reflectance data collected over optically shallow waters of the Florida Keys between June 1997 and August 2011 were used to help understand algorithm performance over optically shallow waters. The in situ data covered a variety of water types in South Florida and the Caribbean Sea, ranging from deep clear waters, turbid coastal waters, and optically shallow waters (Kd_490 range of ~0.03 – 1.29m-1). An algorithm based on Inherent Optical Properties (IOPs) showed the best performance (RMSD turbidity or shallow bottom contamination. Similar results were obtained when only in situ data were used to evaluate algorithm performance. The excellent agreement between satellite-derived remote sensing reflectance (Rrs) and in situ Rrs suggested that

  14. Compensation for photon attenuation in PET

    International Nuclear Information System (INIS)

    Chintu Chen; Ordonez, C.E.; Xiaolin Yu.

    1992-01-01

    CT/MR and PET images usually are not in registration spatially because of differences in the imaging setup. CT, MR and PET imaging parameters that are used regularly for brain studies in their institution are compared, in addition, because the patient orientations in CT/MR and PET scanners are not the same, slice centers are positioned differently relative to the patients anatomy. For application of the new idea of using structural information from CT or MR images in PET image reconstruction for attenuation correction, image registration is required as a first step so that one can obtain a corresponding anatomic map for any selected PET image plane. The authors chose to use the surface-matching technique developed in their laboratories for image registration because this method is retrospective and accurate. After the PET and CT/MR scans are registered, they reslice the CT/MR images along the planes of the PET images. The differences in slice thickness and slice separation, as well as in image resolution between various image modalities are to be considered

  15. Reconstruction of multiple line source attenuation maps

    International Nuclear Information System (INIS)

    Celler, A.; Sitek, A.; Harrop, R.

    1996-01-01

    A simple configuration for a transmission source for the single photon emission computed tomography (SPECT) was proposed, which utilizes a series of collimated line sources parallel to the axis of rotation of a camera. The detector is equipped with a standard parallel hole collimator. We have demonstrated that this type of source configuration can be used to generate sufficient data for the reconstruction of the attenuation map when using 8-10 line sources spaced by 3.5-4.5 cm for a 30 x 40cm detector at 65cm distance from the sources. Transmission data for a nonuniform thorax phantom was simulated, then binned and reconstructed using filtered backprojection (FBP) and iterative methods. The optimum maps are obtained with data binned into 2-3 bins and FBP reconstruction. The activity in the source was investigated for uniform and exponential activity distributions, as well as the effect of gaps and overlaps of the neighboring fan beams. A prototype of the line source has been built and the experimental verification of the technique has started

  16. Transient hepatic attenuation differences in neonates

    International Nuclear Information System (INIS)

    Towbin, Alexander J.; Fleck, Robert; Ying, Jun

    2009-01-01

    A transient hepatic attenuation difference (THAD) is a hepatic perfusion anomaly seen on contrast-enhanced CT scans caused by an alteration in the dual blood supply of the liver. Although THADs have been described in adolescents and adults, they have not previously been described in neonates. We describe the appearance and evaluate the frequency of THADs in neonates ≤1 month of age compared to other infants younger than 2 years. A retrospective study was performed looking at all CT angiograms from 2000 to 2007 in infants <2 years of age. The incidence of THADs was compared among four age groups. Significance was determined using a logistic regression model. The study included 128 CT angiograms. A THAD was seen in 9/26 infants <1 month of age, in 3/50 infants 1 to 6 months of age, in 1/23 infants 6 months to 1 year of age, and in 1/29 infants 1 to 2 years of age. A THAD was found significantly more frequently in infants <1 month of age than in the older age groups (P<0.05). THADs are benign entities that can be seen normally in the neonatal age group. When the characteristic appearance is seen on CT, no further imaging is needed. (orig.)

  17. Agmatine attenuates silica-induced pulmonary fibrosis.

    Science.gov (United States)

    El-Agamy, D S; Sharawy, M H; Ammar, E M

    2014-06-01

    There is a large body of evidence that nitric oxide (NO) formation is implicated in mediating silica-induced pulmonary fibrosis. As a reactive free radical, NO may not only contribute to lung parenchymal tissue injury but also has the ability to combine with superoxide and form a highly reactive toxic species peroxynitrite that can induce extensive cellular toxicity in the lung tissues. This study aimed to explore the effect of agmatine, a known NO synthase inhibitor, on silica-induced pulmonary fibrosis in rats. Male Sprague Dawley rats were treated with agmatine for 60 days following a single intranasal instillation of silica suspension (50 mg in 0.1 ml saline/rat). The results revealed that agmatine attenuated silica-induced lung inflammation as it decreased the lung wet/dry weight ratio, protein concentration, and the accumulation of the inflammatory cells in the bronchoalveolar lavage fluid. Agmatine showed antifibrotic activity as it decreased total hydroxyproline content of the lung and reduced silica-mediated lung inflammation and fibrosis in lung histopathological specimen. In addition, agmatine significantly increased superoxide dismutase (p Agmatine also reduced silica-induced overproduction of pulmonary nitrite/nitrate as well as tumor necrosis factor α. Collectively, these results demonstrate the protective effects of agmatine against the silica-induced lung fibrosis that may be attributed to its ability to counteract the NO production, lipid peroxidation, and regulate cytokine effects. © The Author(s) 2014.

  18. Statins attenuate polymethylmethacrylate-mediated monocyte activation.

    LENUS (Irish Health Repository)

    Laing, Alan J

    2012-02-03

    BACKGROUND: Periprosthetic osteolysis precipitates aseptic loosening of components, increases the risk of periprosthetic fracture and, through massive bone loss, complicates revision surgery and ultimately is the primary cause for failure of joint arthroplasty. The anti-inflammatory properties of HMG-CoA reductase inhibitors belonging to the statin family are well recognized. We investigated a possible role for status in initiating the first stage of the osteolytic cycle, namely monocytic activation. METHODS: We used an in vitro model of the human monocyte\\/macrophage inflammatory response to poly-methylmethacrylate (PMMA) particles after pretreat-ing cells with cerivastatin, a potent member of the statin family. Cell activation based upon production of TNF-alpha and MCP-1 cytokines was analyzed and the intracellular Raf-MEK-ERK signal transduction pathway was evaluated using western blot analysis, to identify its role in cell activation and in any cerivastatin effects observed. RESULTS: We found that pretreatment with cerivastatin significantly abrogates the production of inflammatory cytokines TNF-alpha and MCP-1 by human monocytes in response to polymethylmethacrylate particle activation. This inflammatory activation and attenuation appear to be mediated through the intracellular Raf-MEK-ERK pathway. INTERPRETATION: We propose that by intervening at the upstream activation stage, subsequent osteoclast activation and osteolysis can be suppressed. We believe that the anti-inflammatory properties of statins may potentially play a prophylactic role in the setting of aseptic loosening, and in so doing increase implant longevity.

  19. Minocycline Attenuates Iron-Induced Brain Injury.

    Science.gov (United States)

    Zhao, Fan; Xi, Guohua; Liu, Wenqaun; Keep, Richard F; Hua, Ya

    2016-01-01

    Iron plays an important role in brain injury after intracerebral hemorrhage (ICH). Our previous study found minocycline reduces iron overload after ICH. The present study examined the effects of minocycline on the subacute brain injury induced by iron. Rats had an intracaudate injection of 50 μl of saline, iron, or iron + minocycline. All the animals were euthanized at day 3. Rat brains were used for immunohistochemistry (n = 5-6 per each group) and Western blotting assay (n = 4). Brain swelling, blood-brain barrier (BBB) disruption, and iron-handling proteins were measured. We found that intracerebral injection of iron resulted in brain swelling, BBB disruption, and brain iron-handling protein upregulation (p minocycline with iron significantly reduced iron-induced brain swelling (n = 5, p Minocycline significantly decreased albumin protein levels in the ipsilateral basal ganglia (p minocycline co-injected animals. In conclusion, the present study suggests that minocycline attenuates brain swelling and BBB disruption via an iron-chelation mechanism.

  20. Obesity attenuates gender differences in cardiovascular mortality.

    Science.gov (United States)

    Song, Xin; Tabák, Adam G; Zethelius, Björn; Yudkin, John S; Söderberg, Stefan; Laatikainen, Tiina; Stehouwer, Coen D A; Dankner, Rachel; Jousilahti, Pekka; Onat, Altan; Nilsson, Peter M; Satman, Ilhan; Vaccaro, Olga; Tuomilehto, Jaakko; Qiao, Qing

    2014-10-19

    To estimate cardiovascular disease (CVD) mortality in relation to obesity and gender. Data from 11 prospective cohorts from four European countries including 23 629 men and 21 965 women, aged 24 to 99 years, with a median follow-up of 7.9 years were analyzed. Hazards ratios (HR) for CVD mortality in relation to baseline body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR) were estimated using Cox proportional hazards models with age as the timescale. Men had higher CVD mortality than women in all four BMI categories (obesity defined by WC, WHR or WHtR. The gender difference was slightly smaller in obese than in non-obese individuals; but the interaction was statistically significant only between gender and WC (p = 0.02), and WHtR (p = 0.01). None of the interaction terms was significant among non-diabetic individuals. Men had higher CVD mortality than women across categories of anthropometric measures of obesity. The gender difference was attenuated in obese individuals, which warrants further investigation.

  1. Quantitative SPECT reconstruction for brain distribution with a non-uniform attenuation using a regularizing method

    International Nuclear Information System (INIS)

    Soussaline, F.; Bidaut, L.; Raynaud, C.; Le Coq, G.

    1983-06-01

    An analytical solution to the SPECT reconstruction problem, where the actual attenuation effect can be included, was developped using a regularizing iterative method (RIM). The potential of this approach in quantitative brain studies when using a tracer for cerebrovascular disorders is now under evaluation. Mathematical simulations for a distributed activity in the brain surrounded by the skull and physical phantom studies were performed, using a rotating camera based SPECT system, allowing the calibration of the system and the evaluation of the adapted method to be used. On the simulation studies, the contrast obtained along a profile, was less than 5%, the standard deviation 8% and the quantitative accuracy 13%, for a uniform emission distribution of mean = 100 per pixel and a double attenuation coefficient of μ = 0.115 cm -1 and 0.5 cm -1 . Clinical data obtained after injection of 123 I (AMPI) were reconstructed using the RIM without and with cerebrovascular diseases or lesion defects. Contour finding techniques were used for the delineation of the brain and the skull, and measured attenuation coefficients were assumed within these two regions. Using volumes of interest, selected on homogeneous regions on an hemisphere and reported symetrically, the statistical uncertainty for 300 K events in the tomogram was found to be 12%, the index of symetry was of 4% for normal distribution. These results suggest that quantitative SPECT reconstruction for brain distribution is feasible, and that combined with an adapted tracer and an adequate model physiopathological parameters could be extracted

  2. Insights into the attenuated sorption of organic compounds on black carbon aged in soil.

    Science.gov (United States)

    Luo, Lei; Lv, Jitao; Chen, Zien; Huang, Rixiang; Zhang, Shuzhen

    2017-12-01

    Sorption of organic compounds on fresh black carbons (BCs) can be greatly attenuated in soil over time. We examined herein the changes in surface properties of maize straw-derived BCs (biochars) after aged in a black soil and their effects on the sorptive behaviors of naphthalene, phenanthrene and 1,3-dinitrobenzene. Dissolved fulvic and humic acids extracted from the soil were used to explore the role of dissolved organic carbon (DOC) in the aging of biochars. Chromatography analysis indicated that DOC molecules with relatively large molecular weight were preferentially adsorbed on the biochars during the aging processes. DOC sorption led to blockage of the biochar's micropores according to N 2 and CO 2 adsorption analyses. Surface chemistry of the biochars was also substantially modified, with more O-rich functional groups on the aged biochars compared to the original biochars, as evidenced by Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses. The changes in both the physical and chemical surface properties of biochars by DOC led to significant attenuation of the sorption capacity and nonlinearity of the nonionic organic compounds on the aged biochars. Among the tested organic compounds, phenanthrene was the most attenuated in its sorption by the aging treatments, possibly because of its relatively large molecular size and hydrophobicity. The information can help gain a mechanistic understanding of interactions between BCs and organic compounds in soil environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Underwater image enhancement based on the dark channel prior and attenuation compensation

    Science.gov (United States)

    Guo, Qingwen; Xue, Lulu; Tang, Ruichun; Guo, Lingrui

    2017-10-01

    Aimed at the two problems of underwater imaging, fog effect and color cast, an Improved Segmentation Dark Channel Prior (ISDCP) defogging method is proposed to solve the fog effects caused by physical properties of water. Due to mass refraction of light in the process of underwater imaging, fog effects would lead to image blurring. And color cast is closely related to different degree of attenuation while light with different wavelengths is traveling in water. The proposed method here integrates the ISDCP and quantitative histogram stretching techniques into the image enhancement procedure. Firstly, the threshold value is set during the refinement process of the transmission maps to identify the original mismatching, and to conduct the differentiated defogging process further. Secondly, a method of judging the propagating distance of light is adopted to get the attenuation degree of energy during the propagation underwater. Finally, the image histogram is stretched quantitatively in Red-Green-Blue channel respectively according to the degree of attenuation in each color channel. The proposed method ISDCP can reduce the computational complexity and improve the efficiency in terms of defogging effect to meet the real-time requirements. Qualitative and quantitative comparison for several different underwater scenes reveals that the proposed method can significantly improve the visibility compared with previous methods.

  4. Spectral and kinetic analysis of radiation induced optical attenuation in silica: towards intrinsic fibre optic dosimetry?

    International Nuclear Information System (INIS)

    Borgermans, P.

    2002-01-01

    The document is an abstract of a PhD thesis. The PhD work concerns the detailed investigation of the behaviour of optical fibres in radiation fields such as is the case for various nuclear and space application,s. The core of the work concerns the spectral and kinetic analysis of the radiation induced optical attenuation. Models describing underlying physical phenomena, both for the spectral and the time dimensions, have been developed. The potential of silica optical fibre waveguides for intrinsic dosimetry has been assessed by employing specific properties of radiation induced defects in the silica waveguide material

  5. Attenuation of spin resonance signals in media with the multi-component system of collectivized electrons

    International Nuclear Information System (INIS)

    Vojtenko, V.A.

    1995-01-01

    Universal relaxation theory of spectral line form at electron scattering light with spin flip at scattering of neutrons and at electron paramagnetic resonance, is plotted. Signals of spin resonances are shown to be subjected to strong attenuation caused by mutual transformations of various current carriers in multicomponent spin systems contained in intermetallic actinides with heavy fermions, in HTSC-crystals, in indirect highly alloyed semiconductors, solid solutions and superlattices. Physical reasons of observation of light strong scattering with spin flip in intermetallic actinides with semi-width independent of the wave vector are discussed. 19 refs

  6. An acoustic eikonal equation for attenuating orthorhombic media

    KAUST Repository

    Hao, Qi

    2017-04-06

    Attenuating orthorhombic models are often used to describe the azimuthal variation of the seismic wave velocity and amplitude in finely layered hydrocarbon reservoirs with vertical fractures. In addition to the P-wave related medium parameters, shear wave parameters are also present in the complex eikonal equation needed to describe the P-wave complex-valued traveltime in an attenuating orthorhombic medium, which increases the complexity of using the P-wave traveltime to invert for the medium parameters in practice. Here, we use the acoustic assumption to derive an acoustic eikonal equation that approximately governs the complex-valued traveltime of P-waves in an attenuating orthorhombic medium. For a homogeneous attenuating orthorhombic media, we solve the eikonal equation using a combination of the perturbation method and Shanks transform. For a horizontal attenuating orthorhombic layer, both the real and imaginary part of the complex-valued reflection traveltime have nonhyperbolic behaviors in terms of the source-receiver offset. Similar to the roles of normal moveout (NMO) velocity and anellipticity, the attenuation NMO velocity and the attenuation anellipticity characterize the variation of the imaginary part of the complex-valued reflection traveltime around zero source-receiver offset.

  7. Believing and perceiving: authorship belief modulates sensory attenuation.

    Directory of Open Access Journals (Sweden)

    Andrea Desantis

    Full Text Available Sensory attenuation refers to the observation that self-generated stimuli are attenuated, both in terms of their phenomenology and their cortical response compared to the same stimuli when generated externally. Accordingly, it has been assumed that sensory attenuation might help individuals to determine whether a sensory event was caused by themselves or not. In the present study, we investigated whether this dependency is reciprocal, namely whether sensory attenuation is modulated by prior beliefs of authorship. Participants had to judge the loudness of auditory effects that they believed were either self-generated or triggered by another person. However, in reality, the sounds were always triggered by the participants' actions. Participants perceived the tones' loudness attenuated when they believed that the sounds were self-generated compared to when they believed that they were generated by another person. Sensory attenuation is considered to contribute to the emergence of people's belief of authorship. Our results suggest that sensory attenuation is also a consequence of prior belief about the causal link between an action and a sensory change in the environment.

  8. Statistical Physics

    CERN Document Server

    Mandl, Franz

    1988-01-01

    The Manchester Physics Series General Editors: D. J. Sandiford; F. Mandl; A. C. Phillips Department of Physics and Astronomy, University of Manchester Properties of Matter B. H. Flowers and E. Mendoza Optics Second Edition F. G. Smith and J. H. Thomson Statistical Physics Second Edition E. Mandl Electromagnetism Second Edition I. S. Grant and W. R. Phillips Statistics R. J. Barlow Solid State Physics Second Edition J. R. Hook and H. E. Hall Quantum Mechanics F. Mandl Particle Physics Second Edition B. R. Martin and G. Shaw The Physics of Stars Second Edition A. C. Phillips Computing for Scient

  9. Particle physics

    CERN Document Server

    Martin, Brian R

    2017-01-01

    An accessible and carefully structured introduction to Particle Physics, including important coverage of the Higgs Boson and recent progress in neutrino physics. Fourth edition of this successful title in the Manchester Physics series. Includes information on recent key discoveries including : An account of the discovery of exotic hadrons, beyond the simple quark model; Expanded treatments of neutrino physics and CP violation in B-decays; An updated account of ‘physics beyond the standard model’, including the interaction of particle physics with cosmology; Additional problems in all chapters, with solutions to selected problems available on the book’s website; Advanced material appears in optional starred sections.

  10. Environmental physics

    CERN Document Server

    Smith, Clare

    2001-01-01

    Environmental Physics is a comprehensive introduction to the physical concepts underlying environmental science. The importance and relevance of physics is emphasised by its application to real environmental problems with a wide range of case studies. Applications included cover energy use and production, global climate, the physics of living things, radioactivity, environmental remote sensing, noise pollution and the physics of the Earth. The book makes the subject accessible to those with little physics background, keeping mathematical treatment straightforward. The text is lively and informative, and is supplemented by numerous illustrations, photos, tables of useful data, and a glossary of key terms.

  11. Photon attenuation properties of some thorium, uranium and plutonium compounds

    Energy Technology Data Exchange (ETDEWEB)

    Singh, V. P.; Badiger, N. M. [Karnatak University, Department of Physics, Dharwad-580003, Karnataka (India); Vega C, H. R., E-mail: kudphyvps@rediffmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico)

    2015-10-15

    Mass attenuation coefficients, effective atomic numbers, effective electron densities for nuclear materials; thorium, uranium and plutonium compounds have been studied. The photon attenuation properties for the compounds have been investigated for partial photon interaction processes by photoelectric effect, Compton scattering and pair production. The values of these parameters have been found to change with photon energy and interaction process. The variations of mass attenuation coefficients, effective atomic number and electron density with energy are shown graphically. Moreover, results have shown that these compounds are better shielding and suggesting smaller dimensions. The study would be useful for applications of these materials for gamma ray shielding requirement. (Author)

  12. MNAtoolbox: A Monitored Natural Attenuation Site Screening Program

    Energy Technology Data Exchange (ETDEWEB)

    Borns, David J.; Brady, Patrick V.; Brady, Warren D.; Krupka, Kenneth M.; Spalding, Brian P.; Waters, Robert D.; Zhang, Pengchu

    1999-07-12

    Screening of sites for the potential application and reliance upon monitored natural attenuation (MNA) can be done using MNAtoolbox, a web-based tool for estimating extent of biodegradation, chemical transformation, and dilution. MNAtoolbox uses site-specific input data, where available (default parameters are taken from the literature), to roughly quantify the nature and extent of attenuation at a particular site. Use of MNAtoolbox provides 3 important elements of site evaluation: (1) Identifies likely attenuation pathways, (2) Clearly identifies sites where MNA is inappropriate, and (3) Evaluates data requirements for subsequent reliance on MNA as a sole or partial corrective action.

  13. Phosphatidylserine and caffeine attenuate postexercise mood disturbance and perception of fatigue in humans.

    Science.gov (United States)

    Wells, Adam J; Hoffman, Jay R; Gonzalez, Adam M; Stout, Jeffrey R; Fragala, Maren S; Mangine, Gerald T; McCormack, William P; Jajtner, Adam R; Townsend, Jeremy R; Robinson, Edward H

    2013-06-01

    Phosphatidylserine (PS) may attenuate the adverse effects of physical fatigue. Therefore, we investigated the effects of a multi-ingredient supplement containing 400 mg/d PS and 100 mg/d caffeine (supplement [SUP]) for 2 weeks on measures of cognitive function (CF), reaction time (RT), and mood (MD) following an acute exercise stress. It is hypothesized that PS will maintain preexercise CF and RT scores, while attenuating postexercise fatigue. Participants completed 2 acute bouts of resistance exercise (T1 and T2) separated by 2-week ingestion of SUP or control (CON). Outcome measures were assessed pre- and postexercise. When collapsed across groups, a significant decrease in RT performance was seen in the 60-second reaction drill from pre- to postexercise at T1. All other RT tests were similar from pre- to postexercise at T1. Reaction time was not significantly changed by PS. When collapsed across groups, a significant increase in performance of the serial subtraction test was seen. A significant increase (8.9% and 7.1%) in the number of correct answers and a significant decrease (8.0% and 7.5%) in time to answer were seen from pre- to postworkout at T1 and T2, respectively. A significant increase in total MD score from pre- to postworkout was observed for CON but not for PS at T2. Phosphatidylserine significantly attenuated pre- to postexercise perception of fatigue compared to CON. Ingestion of SUP for 14 days appears to attenuate postexercise MD scores and perception of fatigue, but does not affect CF or RT, in recreationally trained individuals. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. Evaluation of downwelling diffuse attenuation coefficient algorithms in the Red Sea

    KAUST Repository

    Tiwari, Surya Prakash

    2016-05-07

    Despite the importance of the optical properties such as the downwelling diffuse attenuation coefficient for characterizing the upper water column, until recently no in situ optical measurements were published for the Red Sea. Kirby et al. used observations from the Coastal Zone Color Scanner to characterize the spatial and temporal variability of the diffuse attenuation coefficient (Kd(490)) in the Red Sea. To better understand optical variability and its utility in the Red Sea, it is imperative to comprehend the diffuse attenuation coefficient and its relationship with in situ properties. Two apparent optical properties, spectral remote sensing reflectance (Rrs) and the downwelling diffuse attenuation coefficient (Kd), are calculated from vertical profile measurements of downwelling irradiance (Ed) and upwelling radiance (Lu). Kd characterizes light penetration into water column that is important for understanding both the physical and biogeochemical environment, including water quality and the health of ocean environment. Our study tests the performance of the existing Kd(490) algorithms in the Red Sea and compares them against direct in situ measurements within various subdivisions of the Red Sea. Most standard algorithms either overestimated or underestimated with the measured in situ values of Kd. Consequently, these algorithms provided poor retrieval of Kd(490) for the Red Sea. Random errors were high for all algorithms and the correlation coefficients (r2) with in situ measurements were quite low. Hence, these algorithms may not be suitable for the Red Sea. Overall, statistical analyses of the various algorithms indicated that the existing algorithms are inadequate for the Red Sea. The present study suggests that reparameterizing existing algorithms or developing new regional algorithms is required to improve retrieval of Kd(490) for the Red Sea. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is

  15. An analysis of some aspects of the attenuation - Scatter functions in brachytherapy dosimetry

    International Nuclear Information System (INIS)

    Klevenhagen, S.C.

    1996-01-01

    An analysis is presented of the attenuation-scatter functions radial dose functions employed in brachytherapy dosimetry which accounts for the interplay between attenuation and scattering along the radial distance from the source. Some of the characteristics of these functions are still not established with certainty and are subject of misinterpretation. Such issues like whether they should be normalized or not, particularly in relation to the currently employed source strength specification in terms of air kerma, are not as yet agreed. In the literature, the functions are presented either as normalized or non-normalized but the differences between them are wrongly interpreted as being due to either computational or experimental uncertainties. Furthermore, there is uncertainty about the attenuation-scatter ratio very close to the brachytherapy sources and, in the case of some functions, at larger radial distances. Although the function's value at close distance may seem of lesser dosimetric relevance, it is important if one wants the underlying physics to be correct. These problems were studied in this analysis on the basis of the available data. An experiment was also carried out in order to determine the scatter component in the close vicinity to the source. The study is based on the data for Iridium-192 but the discussion and conclusions are relevant to all types of brachytherapy sources. It is concluded in this analysis that: i) it is incorrect to be comparing the normalised with non-normalised functions; ii) only non-normalised (the natural) functions such as that derived by Mesiberger et al (1968) or Sakelliou et al (1992) are corrected for dose calculation systems based on the recommended air kerma source specification; iii) the function should not have a value of unity at r = 0 because of the scatter domination over attenuation in the space around the source and; iv) the Van Kleffens-Star function is in error at larger radial distances. (author). 22 refs, 7

  16. An analysis of some aspects of the attenuation - Scatter functions in brachytherapy dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Klevenhagen, S C [The Royal London Hospital, London (United Kingdom). Dept. of Medical Physics

    1996-08-01

    An analysis is presented of the attenuation-scatter functions radial dose functions employed in brachytherapy dosimetry which accounts for the interplay between attenuation and scattering along the radial distance from the source. Some of the characteristics of these functions are still not established with certainty and are subject of misinterpretation. Such issues like whether they should be normalized or not, particularly in relation to the currently employed source strength specification in terms of air kerma, are not as yet agreed. In the literature, the functions are presented either as normalized or non-normalized but the differences between them are wrongly interpreted as being due to either computational or experimental uncertainties. Furthermore, there is uncertainty about the attenuation-scatter ratio very close to the brachytherapy sources and, in the case of some functions, at larger radial distances. Although the function`s value at close distance may seem of lesser dosimetric relevance, it is important if one wants the underlying physics to be correct. These problems were studied in this analysis on the basis of the available data. An experiment was also carried out in order to determine the scatter component in the close vicinity to the source. The study is based on the data for Iridium-192 but the discussion and conclusions are relevant to all types of brachytherapy sources. It is concluded in this analysis that: i) it is incorrect to be comparing the normalised with non-normalised functions; ii) only non-normalised (the natural) functions such as that derived by Mesiberger et al (1968) or Sakelliou et al (1992) are corrected for dose calculation systems based on the recommended air kerma source specification; iii) the function should not have a value of unity at r = 0 because of the scatter domination over attenuation in the space around the source and; iv) the Van Kleffens-Star function is in error at larger radial distances. 22 refs, 7 figs.

  17. Radiation attenuation by lead and nonlead materials used in radiation shielding garments

    International Nuclear Information System (INIS)

    McCaffrey, J. P.; Shen, H.; Downton, B.; Mainegra-Hing, E.

    2007-01-01

    The attenuating properties of several types of lead (Pb)-based and non-Pb radiation shielding materials were studied and a correlation was made of radiation attenuation, materials properties, calculated spectra and ambient dose equivalent. Utilizing the well-characterized x-ray and gamma ray beams at the National Research Council of Canada, air kerma measurements were used to compare a variety of commercial and pre-commercial radiation shielding materials over mean energy ranges from 39 to 205 keV. The EGSnrc Monte Carlo user code cavity.cpp was extended to provide computed spectra for a variety of elements that have been used as a replacement for Pb in radiation shielding garments. Computed air kerma values were compared with experimental values and with the SRS-30 catalogue of diagnostic spectra available through the Institute of Physics and Engineering in Medicine Report 78. In addition to garment materials, measurements also included pure Pb sheets, allowing direct comparisons to the common industry standards of 0.25 and 0.5 mm 'lead equivalent'. The parameter 'lead equivalent' is misleading, since photon attenuation properties for all materials (including Pb) vary significantly over the energy spectrum, with the largest variations occurring in the diagnostic imaging range. Furthermore, air kerma measurements are typically made to determine attenuation properties without reference to the measures of biological damage such as ambient dose equivalent, which also vary significantly with air kerma over the diagnostic imaging energy range. A single material or combination cannot provide optimum shielding for all energy ranges. However, appropriate choice of materials for a particular energy range can offer significantly improved shielding per unit mass over traditional Pb-based materials

  18. Rational reconstructions of modern physics

    CERN Document Server

    Mittelstaedt, Peter

    2013-01-01

    Newton’s classical physics and its underlying ontology are loaded with several metaphysical hypotheses that cannot be justified by rational reasoning nor by experimental evidence. Furthermore, it is well known that some of these hypotheses are not contained in the great theories of Modern Physics, such as the theory of Special Relativity and Quantum Mechanics. This book shows that, on the basis of Newton’s classical physics and by rational reconstruction, the theory of Special Relativity as well as Quantum Mechanics can be obtained by partly eliminating or attenuating the metaphysical hypotheses. Moreover, it is shown that these reconstructions do not require additional hypotheses or new experimental results. In the second edition the rational reconstructions are completed with respect to General Relativity and Cosmology. In addition, the statistics of quantum objects is elaborated in more detail with respect to the rational reconstruction of quantum mechanics. The new material completes the approach of t...

  19. Telmisartan attenuates diabetes induced depression in rats.

    Science.gov (United States)

    Aswar, Urmila; Chepurwar, Shilpa; Shintre, Sumit; Aswar, Manoj

    2017-04-01

    Role of brain renin angiotensin system (RAS) is well understood and various clinical studies have proposed neuroprotective effects of ARB's. It is also assumed that diabetic depression is associated with activation of brain RAS, HPA axis dysregulation and brain inflammatory events. Therefore, the present study was designed to investigate the antidepressant effect of low dose telmisartan (TMS) in diabetes induced depression (DID) in rats. Diabetes was induced by injecting streptozotocin. After 21days of treatment the rats were subjected to forced swim test (FST). The rats, with increased immobility time, were considered depressed and were treated with vehicle or TMS (0.05mg/kg, po) or metformin (200mg/kg, po) or fluoxetine (20mg/kg, po). A separate group was also maintained to study the combination of metformin and TMS. At the end of 21days of treatments, FST, open field test (OFT) and elevated plus maze (EPM) paradigm were performed. Blood was drawn to estimate serum cortisol, nitric oxide (NO), interleukin-6 (IL-6) and interleukin-1β (IL-1β). Persistent hyperglycemia resulted in depression and anxiety in rats as observed by increased immobility, reduced latency for immobility, reduced open arm entries and time spent. The depressed rats showed a significant rise in serum cortisol, NO, IL-6 and IL-1β (pdepression and anxiety. It also significantly attenuated serum cortisol, NO, IL-6 and IL-1β (pdepressive mood, reduces pro-inflammatory mediators and ameliorates the HPA axis function; thereby providing beneficial effects in DID. Copyright © 2016. Published by Elsevier Urban & Partner Sp. z o.o.

  20. Urban physics

    NARCIS (Netherlands)

    Blocken, B.J.E.

    2012-01-01

    Urban Physics is the multiscale and interdisciplinary research area dealing with physical processes in urban environments that influence our everyday health, comfort and productivity. It involves disciplines ranging from mesoscale meteorology to human thermophysiology. The introductory lecture

  1. Physics matters

    CERN Document Server

    Natarajan, Vasant

    2017-01-01

    This is a collection of essays on physics topics. It is written as a textbook for non-physics science and arts students, at the undergraduate level. Topics covered include cellphone radiation, lasers, the twin paradox, and more.

  2. MRI-guided attenuation correction in whole-body PET/MR. Assessment of the effect of bone attenuation

    International Nuclear Information System (INIS)

    Akbarzadeh, A.; Ay, M.R.; Ahmadian, A.; Riahi Alam, N.; Zaidi, H.

    2013-01-01

    Hybrid positron emission tomography (PET)/MRI presents many advantages in comparison with its counterpart PET/CT in terms of improved soft-tissue contrast, decrease in radiation exposure, and truly simultaneous and multi-parametric imaging capabilities. However, the lack of well-established methodology for MR-based attenuation correction is hampering further development and wider acceptance of this technology. We assess the impact of ignoring bone attenuation and using different tissue classes for generation of the attenuation map on the accuracy of attenuation correction of PET data. This work was performed using simulation studies based on the XCAT phantom and clinical input data. For the latter, PET and CT images of patients were used as input for the analytic simulation model using realistic activity distributions where CT-based attenuation correction was utilized as reference for comparison. For both phantom and clinical studies, the reference attenuation map was classified into various numbers of tissue classes to produce three (air, soft tissue and lung), four (air, lungs, soft tissue and cortical bones) and five (air, lungs, soft tissue, cortical bones and spongeous bones) class attenuation maps. The phantom studies demonstrated that ignoring bone increases the relative error by up to 6.8% in the body and up to 31.0% for bony regions. Likewise, the simulated clinical studies showed that the mean relative error reached 15% for lesions located in the body and 30.7% for lesions located in bones, when neglecting bones. These results demonstrate an underestimation of about 30% of tracer uptake when neglecting bone, which in turn imposes substantial loss of quantitative accuracy for PET images produced by hybrid PET/MRI systems. Considering bones in the attenuation map will considerably improve the accuracy of MR-guided attenuation correction in hybrid PET/MR to enable quantitative PET imaging on hybrid PET/MR technologies. (author)

  3. Physical literacy

    OpenAIRE

    Roučka, Ladislav

    2013-01-01

    Topic: Physical literacy Goals: The aproximation of physical literacy, collection and evaluation questionnaires of physical literacy knowledge and students anamnesis. Description of applicants progress in the specific movement skills. Method: Unified questionnaires was used for obtaining informations. We make video for movement analysis. Results: The results didn't obtain our expectation that students are able to express precisely the content of physical literacy by specific skills. However, ...

  4. Physical activity (PA) and the disablement process

    DEFF Research Database (Denmark)

    Schultz-Larsen, Kirsten; Rahmanfard, Naghmeh; Holst, Claus

    2012-01-01

    . Among older women, the association between RPA and incidence of disability was attenuated in analyses that controlled for baseline mobility function. Thus, the association between physical activity and mortality reflected processes different from those underlying a simple relation between physical...... activity, disability and mortality. Physical activity was an ubiquitous predictor of longevity, but only for women....... community-living persons, aged 75-83 years, we evaluated the 1021 who reported no disability in basic activities of daily living. Participants were followed for a median of 8.34 years in public registers to determine onset of disability and mortality. RPA predicted mortality in older women (HR=1.77, 95%CI=1...

  5. Astroparticle Physics

    CERN Multimedia

    CERN. Geneva; J. Carr

    2001-01-01

    The lectures will introduce the emerging field of Astroparticle Physics which links particle physics and astrophysics. Starting from the Big Bang, the course will describe how particle physics explains certain features of the natural world and the features remainning to be understood. The subjects covered will include dark matter, gamma and neutrino astronomy, cosmic rays and gravity waves.

  6. Physical ergonomics

    NARCIS (Netherlands)

    Looze, M.P. de; Koningsveld, E.

    2013-01-01

    Physical ergonomics deals with the physical load on the human body when performing activities like work, sports, jobs at home or dealing with products. With regard to the exposure to physical loads and its potential effects on the human body, the presented framework is helpful. In this article we

  7. Collider Physics

    Indian Academy of Sciences (India)

    This is summary of the activities of the working group on collider physics in the IXth Workshop on High Energy Physics Phenomenology (WHEPP-9) held at the Institute of Physics, Bhubaneswar, India in January 2006. Some of the work subsequently done on these problems by the subgroups formed during the workshop is ...

  8. Physics Demonstrations

    Science.gov (United States)

    Bringing Physics Presentations to Students for Presenters Remember why you became a scientist help students develop a deeper understanding of the concepts of force and motion. Physics of Sports Grades 4-12 Fermilab scientists guide a discussion and exploration of the impact physics has in a variety

  9. Analytical inversion formula for uniformly attenuated fan-beam projections

    International Nuclear Information System (INIS)

    Weng, Y.; Zeng, G.L.; Gullberg, G.T.

    1997-01-01

    In deriving algorithms to reconstruct single photon emission computed tomography (SPECT) projection data, it is important that the algorithm compensates for photon attenuation in order to obtain quantitative reconstruction results. A convolution backprojection algorithm was derived by Tretiak and Metz to reconstruct two-dimensional (2-D) transaxial slices from uniformly attenuated parallel-beam projections. Using transformation of coordinates, this algorithm can be modified to obtain a formulation useful to reconstruct uniformly attenuated fan-beam projections. Unlike that for parallel-beam projections, this formulation does not produce a filtered backprojection reconstruction algorithm but instead has a formulation that is an inverse integral operator with a spatially varying kernel. This algorithm thus requires more computation time than does the filtered backprojection reconstruction algorithm for the uniformly attenuated parallel-beam case. However, the fan-beam reconstructions demonstrate the same image quality as that of parallel-beam reconstructions

  10. Magnitude corrections for attenuation in the upper mantle

    International Nuclear Information System (INIS)

    Anon.

    1978-01-01

    Since 1969, a consistent discrepancy in seismic magnitudes of nuclear detonations at NTS compared with magnitudes of detonations elsewhere in the world has been observed. This discrepancy can be explained in terms of a relatively high seismic attenuation for compressional waves in the upper mantle beneath the NTS and in certain other locations. A correction has been developed for this attenuation based on a relationship between the velocity of compressional waves at the top of the earth's mantle (just beneath the Mohorovicic discontinuity) and the seismic attenuation further down in the upper mantle. Our new definition of body-wave magnitude includes corrections for attenuation in the upper mantle at both ends of the teleseismic body-wave path. These corrections bring the NTS oservations into line with measurements of foreign events, and enable one to make more reliable estimates of yields of underground nuclear explosions, wherever the explosion occurs

  11. Validity of the CT to attenuation coefficient map conversion methods

    International Nuclear Information System (INIS)

    Faghihi, R.; Ahangari Shahdehi, R.; Fazilat Moadeli, M.

    2004-01-01

    The most important commercialized methods of attenuation correction in SPECT are based on attenuation coefficient map from a transmission imaging method. The transmission imaging system can be the linear source of radioelement or a X-ray CT system. The image of transmission imaging system is not useful unless to replacement of the attenuation coefficient or CT number with the attenuation coefficient in SPECT energy. In this paper we essay to evaluate the validity and estimate the error of the most used method of this transformation. The final result shows that the methods which use a linear or multi-linear curve accept a error in their estimation. The value of mA is not important but the patient thickness is very important and it can introduce a error more than 10 percent in the final result

  12. The use of microperforated plates to attenuate cavity resonances

    DEFF Research Database (Denmark)

    Fenech, Benjamin; Keith, Graeme; Jacobsen, Finn

    2006-01-01

    The use of microperforated plates to introduce damping in a closed cavity is examined. By placing a microperforated plate well inside the cavity instead of near a wall as traditionally done in room acoustics, high attenuation can be obtained for specific acoustic modes, compared with the lower...... attenuation that can be obtained in a broad frequency range with the conventional position of the plate. An analytical method for predicting the attenuation is presented. The method involves finding complex eigenvalues and eigenfunctions for the modified cavity and makes it possible to predict Green......'s functions. The results, which are validated experimentally, show that a microperforated plate can provide substantial attenuation of modes in a cavity. One possible application of these findings is the treatment of boiler tones in heat-exchanger cavities....

  13. Multi-resolution inversion algorithm for the attenuated radon transform

    KAUST Repository

    Barbano, Paolo Emilio; Fokas, Athanasios S.

    2011-01-01

    We present a FAST implementation of the Inverse Attenuated Radon Transform which incorporates accurate collimator response, as well as artifact rejection due to statistical noise and data corruption. This new reconstruction procedure is performed

  14. Numerical Speadsheet Modeling of Natural Attenuation for Groundwater Contaminant Plumes

    National Research Council Canada - National Science Library

    Twesme, Troy

    1999-01-01

    .... The model was used to evaluate natural attenuation for removal of a trichloroethylene (TCE) plume from a surficial aquifer containing three regions with distinctly different processes for degradation of TCE...

  15. Practical method of breast attenuation correction for cardiac SPECT

    International Nuclear Information System (INIS)

    Oliveira, Anderson de; Nogueira, Tindyua; Gutterres, Ricardo Fraga; Megueriam, Berdj Aram; Santos, Goncalo Rodrigues dos

    2007-01-01

    The breast attenuation effects on SPECT (Single Photon Emission Tomography) myocardium perfusion procedures have been lately scope of continuous inquiry. The requested attenuation correction factors are usually achieved by transmission analysis, making up the exposure of a standard external source to the SPECT, as a routine step. However, its high cost makes this methodology not fully available to the most of nuclear medicines services in Brazil and abroad. To overcome the problem, a new trend is presented in this work, implementing computational models to balance the breast attenuation effects on the left ventricle anterior wall, during myocardium perfusion scintigraphy procedures with SPECT. A neural network was put on in order to provide the attenuation correction indexes, based upon the following patients individual biotypes features: mass, age, height, chest and breast thicknesses, heart size, as well as the imparted activity intake levels. (author)

  16. Practical method of breast attenuation correction for cardiac SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Anderson de; Nogueira, Tindyua; Gutterres, Ricardo Fraga [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil). Coordenacao Geral de Instalacoes Medicas e Industriais (CGMI)]. E-mails: anderson@cnen.gov.br; tnogueira@cnen.gov.br; rguterre@cnen.gov.br; Megueriam, Berdj Aram [Instituto Nacional do Cancer (INCA), Rio de Janeiro, RJ (Brazil)]. E-mail: megueriam@hotmail.com; Santos, Goncalo Rodrigues dos [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)]. E-mail: goncalo@cnen.gov.br

    2007-07-01

    The breast attenuation effects on SPECT (Single Photon Emission Tomography) myocardium perfusion procedures have been lately scope of continuous inquiry. The requested attenuation correction factors are usually achieved by transmission analysis, making up the exposure of a standard external source to the SPECT, as a routine step. However, its high cost makes this methodology not fully available to the most of nuclear medicines services in Brazil and abroad. To overcome the problem, a new trend is presented in this work, implementing computational models to balance the breast attenuation effects on the left ventricle anterior wall, during myocardium perfusion scintigraphy procedures with SPECT. A neural network was put on in order to provide the attenuation correction indexes, based upon the following patients individual biotypes features: mass, age, height, chest and breast thicknesses, heart size, as well as the imparted activity intake levels. (author)

  17. 2 original article non-attenuation of highly pathogenic avian

    African Journals Online (AJOL)

    Dr Oboro VO

    AFRICAN JOURNAL OF CLINICAL AND EXPERIMENTAL MICROBIOLOGY JANUARY 2010. ISBN 1595-689X ... NON-ATTENUATION OF HIGHLY PATHOGENIC AVIAN INFLUENZA. H5N1 BY .... Diagnostic PCR was conducted to determine ...

  18. Gamma ray attenuation coefficient measurement for neutron-absorbent materials

    International Nuclear Information System (INIS)

    Jalali, Majid; Mohammadi, Ali

    2008-01-01

    The compounds Na 2 B 4 O 7 , H 3 BO 3 , CdCl 2 and NaCl and their solutions attenuate gamma rays in addition to neutron absorption. These compounds are widely used in the shielding of neutron sources, reactor control and neutron converters. Mass attenuation coefficients of gamma related to the four compounds aforementioned, in energies 662, 778.9, 867.38, 964.1, 1085.9, 1173, 1212.9, 1299.1,1332 and 1408 keV, have been determined by the γ rays transmission method in a good geometry setup; also, these coefficients were calculated by MCNP code. A comparison between experiments, simulations and Xcom code has shown that the study has potential application for determining the attenuation coefficient of various compound materials. Experiment and computation show that H 3 BO 3 with the lowest average Z has the highest gamma ray attenuation coefficient among the aforementioned compounds

  19. Natural Attenuation of the Persistent Chemical Warfare Agent ...

    Science.gov (United States)

    Report This project studied the influence of temperature on the natural attenuation of VX from five types of porous/permeable materials: unsealed concrete, plywood, rubber escalator handrail, high density polyethylene (HDPE) plastic, and acoustic ceiling tile.

  20. An acoustic eikonal equation for attenuating VTI media

    KAUST Repository

    Hao, Qi; Alkhalifah, Tariq Ali

    2016-01-01

    We present an acoustic eikonal equation governing the complex-valued travel time of P-waves in attenuating, transversely isotropic media with a vertical symmetry axis (VTI). This equation is based on the assumption that the Pwave complex

  1. An acoustic eikonal equation for attenuating orthorhombic media

    KAUST Repository

    Hao, Qi; Alkhalifah, Tariq Ali

    2017-01-01

    solve the eikonal equation using a combination of the perturbation method and Shanks transform. For a horizontal attenuating orthorhombic layer, both the real and imaginary part of the complex-valued reflection traveltime have nonhyperbolic behaviors

  2. MASS BALANCE: A KEY TO ADVANCING MONITORED AND ENHANCED ATTENUATION FOR CHLORINATED SOLVENTS

    Energy Technology Data Exchange (ETDEWEB)

    Looney, B; Karen Vangelas, K; Karen-M Adams, K; Francis H. Chappelle; Tom O. Early; Claire H. Sink

    2006-06-30

    removal is needed or when to turn off active remediation and transition to MNA. It cannot be used to evaluate potential enhancement options (unless a long period of post enhancement monitoring is planned). It provides only indirect information about process and treats the plume as a ''black box''. The empirical approach has the advantage that, when sufficient monitoring data are available, the attenuation capacity can be defined inexpensively and with a high degree of certainty. Alternatively, a deterministic approach can be used to assess mass balance and plume stability. In this approach, the physical, chemical, and biological attenuation processes are used to assess contaminant loading and attenuation. The deterministic approach has the advantage that, when sufficient hydrologic, geochemical, and microbiological data are available, it is possible to project how a system will respond to contaminant removal actions or enhancements of natural attenuation processes. The ''black box'' of the plume is taken apart, quantified, and put back together again. The disadvantage of the deterministic approach is that it is difficult to measure all or most of the relevant hydrologic, geochemical, and biological parameters with any certainty. Case studies over the past decade demonstrate that empirical and deterministic approaches to MNA/EA are not mutually exclusive. These studies document that improved decision support and efficiency result by combining these methods based on the individual challenges presented by a given site. Whenever possible, the empirical approach is used to quantify mass loading and attenuation capacity (mass of contaminant/unit time) at particular sites. This is the most effective way to demonstrate the efficiency of ongoing natural attenuation processes in accordance with current regulatory guidance. But in addition, the monitoring well networks needed to apply the empirical approach can also yield estimates of the

  3. Frequency scaling of slant-path atmospheric attenuation in the absence of rain for millimeter-wave links

    Science.gov (United States)

    Lucas-Vegas, María. José; Riera, José Manuel

    2016-11-01

    Broadband satellite communications systems, either used for broadcast or fixed satellite services, have grown continuously in recent years. This has led to the use of higher frequency bands, from the Ku (14/11 GHz) to the Ka band (30/20 GHz) in the last decade, and with the expectation of using the Q/V band (50/40 GHz) and even the W band (75-110 GHz) in the future. As frequency increases, radio wave propagation effects in the slant-path within the troposphere are becoming more and more relevant. The objective of this research is the proposal of frequency scaling approximations for the total attenuation in the absence of rain, a condition that occurs during the highest percentages of time, usually more than 95% in temperate climates. There is a strong relationship between total attenuation at different frequencies, as it arises from the same physical phenomena, namely, the presence of oxygen, water vapor, and clouds in the slant path. This strong relationship allows frequency scaling estimations to be proposed. In particular, polynomials for instantaneous frequency scaling of total attenuation under these conditions have been calculated for a set of frequencies in the range 10-100 GHz, based on atmospheric profiles of 60 sites from all over the world and physical models of attenuation. Global polynomials are provided for the 72 combinations of nine significant frequencies, which can be used to estimate attenuation at a frequency band from its known value at a different one. Refined expressions have also been calculated for different climatic zones, providing more precise estimations.

  4. Dose reduction using a dynamic, piecewise-linear attenuator

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Scott S., E-mail: sshsieh@stanford.edu [Department of Radiology, Stanford University, Stanford, California 94305 and Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Fleischmann, Dominik [Department of Radiology, Stanford University, Stanford, California 94305 (United States); Pelc, Norbert J. [Department of Radiology, Stanford University, Stanford, California 94305 and Department of Bioengineering, Stanford University, Stanford, California 94305 (United States)

    2014-02-15

    Purpose: The authors recently proposed a dynamic, prepatient x-ray attenuator capable of producing a piecewise-linear attenuation profile customized to each patient and viewing angle. This attenuator was intended to reduce scatter-to-primary ratio (SPR), dynamic range, and dose by redistributing flux. In this work the authors tested the ability of the attenuator to reduce dose and SPR in simulations. Methods: The authors selected four clinical applications, including routine full field-of-view scans of the thorax and abdomen, and targeted reconstruction tasks for an abdominal aortic aneurysm and the pancreas. Raw data were estimated by forward projection of the image volume datasets. The dynamic attenuator was controlled to reduce dose while maintaining peak variance by solving a convex optimization problem, assuminga priori knowledge of the patient anatomy. In targeted reconstruction tasks, the noise in specific regions was given increased weighting. A system with a standard attenuator (or “bowtie filter”) was used as a reference, and used either convex optimized tube current modulation (TCM) or a standard TCM heuristic. The noise of the scan was determined analytically while the dose was estimated using Monte Carlo simulations. Scatter was also estimated using Monte Carlo simulations. The sensitivity of the dynamic attenuator to patient centering was also examined by shifting the abdomen in 2 cm intervals. Results: Compared to a reference system with optimized TCM, use of the dynamic attenuator reduced dose by about 30% in routine scans and 50% in targeted scans. Compared to the TCM heuristics which are typically used withouta priori knowledge, the dose reduction is about 50% for routine scans. The dynamic attenuator gives the ability to redistribute noise and variance and produces more uniform noise profiles than systems with a conventional bowtie filter. The SPR was also modestly reduced by 10% in the thorax and 24% in the abdomen. Imaging with the dynamic

  5. Impact of Scattering Model on Disdrometer Derived Attenuation Scaling

    Science.gov (United States)

    Zemba, Michael; Luini, Lorenzo; Nessel, James; Riva, Carlo (Compiler)

    2016-01-01

    NASA Glenn Research Center (GRC), the Air Force Research Laboratory (AFRL), and the Politecnico di Milano (POLIMI) are currently entering the third year of a joint propagation study in Milan, Italy utilizing the 20 and 40 GHz beacons of the Alphasat TDP5 Aldo Paraboni scientific payload. The Ka- and Q-band beacon receivers were installed at the POLIMI campus in June of 2014 and provide direct measurements of signal attenuation at each frequency. Collocated weather instrumentation provides concurrent measurement of atmospheric conditions at the receiver; included among these weather instruments is a Thies Clima Laser Precipitation Monitor (optical disdrometer) which records droplet size distributions (DSD) and droplet velocity distributions (DVD) during precipitation events. This information can be used to derive the specific attenuation at frequencies of interest and thereby scale measured attenuation data from one frequency to another. Given the ability to both predict the 40 GHz attenuation from the disdrometer and the 20 GHz timeseries as well as to directly measure the 40 GHz attenuation with the beacon receiver, the Milan terminal is uniquely able to assess these scaling techniques and refine the methods used to infer attenuation from disdrometer data.In order to derive specific attenuation from the DSD, the forward scattering coefficient must be computed. In previous work, this has been done using the Mie scattering model, however, this assumes a spherical droplet shape. The primary goal of this analysis is to assess the impact of the scattering model and droplet shape on disdrometer derived attenuation predictions by comparing the use of the Mie scattering model to the use of the T-matrix method, which does not assume a spherical droplet. In particular, this paper will investigate the impact of these two scattering approaches on the error of the resulting predictions as well as on the relationship between prediction error and rain rate.

  6. Wave attenuation across a tidal marsh in San Francisco Bay

    Science.gov (United States)

    Foster-Martinez, Madeline R.; Lacy, Jessica; Ferner, Matthew C.; Variano, Evan A.

    2018-01-01

    Wave attenuation is a central process in the mechanics of a healthy salt marsh. Understanding how wave attenuation varies with vegetation and hydrodynamic conditions informs models of other marsh processes that are a function of wave energy (e.g. sediment transport) and allows for the incorporation of marshes into coastal protection plans. Here, we examine the evolution of wave height across a tidal salt marsh in San Francisco Bay. Instruments were deployed along a cross-shore transect, starting on the mudflat and crossing through zones dominated by Spartina foliosa and Salicornia pacifica. This dataset is the first to quantify wave attenuation for these vegetation species, which are abundant in the intertidal zone of California estuaries. Measurements were collected in the summer and winter to assess seasonal variation in wave attenuation. Calculated drag coefficients of S. foliosa and S. pacifica were similar, indicating equal amounts of vegetation would lead to similar energy dissipation; however, S. pacifica has much greater biomass close to the bed (<20 cm) and retains biomass throughout the year, and therefore, it causes more total attenuation. S. foliosa dies back in the winter, and waves often grow across this section of the marsh. For both vegetation types, attenuation was greatest for low water depths, when the vegetation was emergent. For both seasons, attenuation rates across S. pacifica were the highest and were greater than published attenuation rates across similar (Spartina alterniflora) salt marshes for the comparable depths. These results can inform designs for marsh restorations and management plans in San Francisco Bay and other estuaries containing these species.

  7. Characterizing X-ray Attenuation of Containerized Cargo

    Energy Technology Data Exchange (ETDEWEB)

    Birrer, N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Divin, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Glenn, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Martz, H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wang, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-08-02

    X-ray inspection systems can be used to detect radiological and nuclear threats in imported cargo. In order to better understand performance of these systems, the attenuation characteristics of imported cargo need to be determined. This project focused on developing image processing algorithms for segmenting cargo and using x-ray attenuation to quantify equivalent steel thickness to determine cargo density. These algorithms were applied to over 450 cargo radiographs. The results are summarized in this report.

  8. Nuclear equipment to determine soil and water mass attenuation coefficients

    International Nuclear Information System (INIS)

    Zucchi, O.L.A.D.; Nascimento Filho, V.F. do

    1984-01-01

    The feasibility of substituting the monochannel gamma spectrometer, traditionally used in the gamma ray attenuation technique, for a less sophisticated and less expensive system of integral counting is studied. The proposed system can be operated by a non-specialized person. Three detection systems were used in the determination of the mass attenuation coefficients for different types of soil and for water. (M.A.C.) [pt

  9. Patient position alters attenuation effects in multipinhole cardiac SPECT.

    Science.gov (United States)

    Timmins, Rachel; Ruddy, Terrence D; Wells, R Glenn

    2015-03-01

    Dedicated cardiac cameras offer improved sensitivity over conventional SPECT cameras. Sensitivity gains are obtained by large numbers of detectors and novel collimator arrangements such as an array of multiple pinholes that focus on the heart. Pinholes lead to variable amounts of attenuation as a source is moved within the camera field of view. This study evaluated the effects of this variable attenuation on myocardial SPECT images. Computer simulations were performed for a set of nine point sources distributed in the left ventricular wall (LV). Sources were placed at the location of the heart in both an anthropomorphic and a water-cylinder computer phantom. Sources were translated in x, y, and z by up to 5 cm from the center. Projections were simulated with and without attenuation and the changes in attenuation were compared. A LV with an inferior wall defect was also simulated in both phantoms over the same range of positions. Real camera data were acquired on a Discovery NM530c camera (GE Healthcare, Haifa, Israel) for five min in list-mode using an anthropomorphic phantom (DataSpectrum, Durham, NC) with 100 MBq of Tc-99m in the LV. Images were taken over the same range of positions as the simulations and were compared based on the summed perfusion score (SPS), defect width, and apparent defect uptake for each position. Point sources in the water phantom showed absolute changes in attenuation of ≤8% over the range of positions and relative changes of ≤5% compared to the apex. In the anthropomorphic computer simulations, absolute change increased to 20%. The changes in relative attenuation caused a change in SPS of position-dependent changes were removed with attenuation correction. Translation of a source relative to a multipinhole camera caused only small changes in homogeneous phantoms with SPS changing position-dependent changes in attenuation.

  10. Bulk sample self-attenuation correction by transmission measurement

    International Nuclear Information System (INIS)

    Parker, J.L.; Reilly, T.D.

    1976-01-01

    Various methods used in either finding or avoiding the attenuation correction in the passive γ-ray assay of bulk samples are reviewed. Detailed consideration is given to the transmission method, which involves experimental determination of the sample linear attenuation coefficient by measuring the transmission through the sample of a beam of gamma rays from an external source. The method was applied to box- and cylindrically-shaped samples

  11. Adaptive attenuation of aliased ground roll using the shearlet transform

    Science.gov (United States)

    Hosseini, Seyed Abolfazl; Javaherian, Abdolrahim; Hassani, Hossien; Torabi, Siyavash; Sadri, Maryam

    2015-01-01

    Attenuation of ground roll is an essential step in seismic data processing. Spatial aliasing of the ground roll may cause the overlap of the ground roll with reflections in the f-k domain. The shearlet transform is a directional and multidimensional transform that separates the events with different dips and generates subimages in different scales and directions. In this study, the shearlet transform was used adaptively to attenuate aliased and non-aliased ground roll. After defining a filtering zone, an input shot record is divided into segments. Each segment overlaps adjacent segments. To apply the shearlet transform on each segment, the subimages containing aliased and non-aliased ground roll, the locations of these events on each subimage are selected adaptively. Based on these locations, mute is applied on the selected subimages. The filtered segments are merged together, using the Hanning function, after applying the inverse shearlet transform. This adaptive process of ground roll attenuation was tested on synthetic data, and field shot records from west of Iran. Analysis of the results using the f-k spectra revealed that the non-aliased and most of the aliased ground roll were attenuated using the proposed adaptive attenuation procedure. Also, we applied this method on shot records of a 2D land survey, and the data sets before and after ground roll attenuation were stacked and compared. The stacked section after ground roll attenuation contained less linear ground roll noise and more continuous reflections in comparison with the stacked section before the ground roll attenuation. The proposed method has some drawbacks such as more run time in comparison with traditional methods such as f-k filtering and reduced performance when the dip and frequency content of aliased ground roll are the same as those of the reflections.

  12. Broad beam X-rays attenuation in silicum glass

    International Nuclear Information System (INIS)

    Risticj, Dj.; Vukovicj, S.; Markovicj, P.

    1987-01-01

    Using broad beam geometry the attenuation for domestic silicum glass have been studied for constant X-ray potentials from 50 to 150 kV. The density of the silicium glass was 2,5x10 3 kg/m 3 . From the attenuation curves the half value layers were obtained. The use of this glass as the biological shield is pointed out. (author). 2 refs.; 2 tabs.; 2 figs

  13. Game physics

    CERN Document Server

    Eberly, David H

    2010-01-01

    ""Game Physics, 2nd Edition"" provides clear descriptions of the mathematics and algorithms needed to create a powerful physics engine - while providing a solid reference for all of the math you will encounter anywhere in game development: quaternions, linear algebra, and calculus. Implementing physical simulations for real-time games is a complex task that requires a solid understanding of a wide range of concepts from the fields of mathematics and physics. Previously, the relevant information could only be gleaned through obscure research papers. Thanks to ""Game Physics"", all this informa

  14. Cosmoparticle physics

    CERN Document Server

    Khlopov, M Yu

    1999-01-01

    Since the 1980s the cross-disciplinary, multidimensional field of links between cosmology and particle physics has been widely recognised by theorists, studying cosmology, particle and nuclear physics, gravity, as well as by astrophysicists, astronomers, space physicists, experimental particle and nuclear physicists, mathematicians and engineers.The relationship between cosmology and particle physics is now one of the important topics of discussion at any scientific meeting both on astrophysics and high energy physics.Cosmoparticle physics is the result of the mutual relationship between cosmo

  15. Understanding physics

    CERN Document Server

    Mansfield, Michael

    2011-01-01

    Understanding Physics - Second edition is a comprehensive, yet compact, introductory physics textbook aimed at physics undergraduates and also at engineers and other scientists taking a general physics course. Written with today's students in mind, this text covers the core material required by an introductory course in a clear and refreshing way. A second colour is used throughout to enhance learning and understanding. Each topic is introduced from first principles so that the text is suitable for students without a prior background in physics. At the same time the book is designed to enable

  16. Trade-off of Elastic Structure and Q in Interpretations of Seismic Attenuation

    Science.gov (United States)

    Deng, Wubing; Morozov, Igor B.

    2017-10-01

    The quality factor Q is an important phenomenological parameter measured from seismic or laboratory seismic data and representing wave-energy dissipation rate. However, depending on the types of measurements and models or assumptions about the elastic structure, several types of Qs exist, such as intrinsic and scattering Qs, coda Q, and apparent Qs observed from wavefield fluctuations. We consider three general types of elastic structures that are commonly encountered in seismology: (1) shapes and dimensions of rock specimens in laboratory studies, (2) geometric spreading or scattering in body-, surface- and coda-wave studies, and (3) reflectivity on fine layering in reflection seismic studies. For each of these types, the measured Q strongly trades off with the (inherently limited) knowledge about the respective elastic structure. For the third of the above types, the trade-off is examined quantitatively in this paper. For a layered sequence of reflectors (e.g., an oil or gas reservoir or a hydrothermal zone), reflection amplitudes and phases vary with frequency, which is analogous to a reflection from a contrast in attenuation. We demonstrate a quantitative equivalence between phase-shifted reflections from anelastic zones and reflections from elastic layering. Reflections from the top of an elastic layer followed by weaker reflections from its bottom can appear as resulting from a low Q within or above this layer. This apparent Q can be frequency-independent or -dependent, according to the pattern of thin layering. Due to the layering, the interpreted Q can be positive or negative, and it can depend on source-receiver offsets. Therefore, estimating Q values from frequency-dependent or phase-shifted reflection amplitudes always requires additional geologic or rock-physics constraints, such as sparseness and/or randomness of reflectors, the absence of attenuation in certain layers, or specific physical mechanisms of attenuation. Similar conclusions about the

  17. Transcranial Alternating Current Stimulation Attenuates Neuronal Adaptation.

    Science.gov (United States)

    Kar, Kohitij; Duijnhouwer, Jacob; Krekelberg, Bart

    2017-03-01

    We previously showed that brief application of 2 mA (peak-to-peak) transcranial currents alternating at 10 Hz significantly reduces motion adaptation in humans. This is but one of many behavioral studies showing that weak currents applied to the scalp modulate neural processing. Transcranial stimulation has been shown to improve perception, learning, and a range of clinical symptoms. Few studies, however, have measured the neural consequences of transcranial current stimulation. We capitalized on the strong link between motion perception and neural activity in the middle temporal (MT) area of the macaque monkey to study the neural mechanisms that underlie the behavioral consequences of transcranial alternating current stimulation. First, we observed that 2 mA currents generated substantial intracranial fields, which were much stronger in the stimulated hemisphere (0.12 V/m) than on the opposite side of the brain (0.03 V/m). Second, we found that brief application of transcranial alternating current stimulation at 10 Hz reduced spike-frequency adaptation of MT neurons and led to a broadband increase in the power spectrum of local field potentials. Together, these findings provide a direct demonstration that weak electric fields applied to the scalp significantly affect neural processing in the primate brain and that this includes a hitherto unknown mechanism that attenuates sensory adaptation. SIGNIFICANCE STATEMENT Transcranial stimulation has been claimed to improve perception, learning, and a range of clinical symptoms. Little is known, however, how transcranial current stimulation generates such effects, and the search for better stimulation protocols proceeds largely by trial and error. We investigated, for the first time, the neural consequences of stimulation in the monkey brain. We found that even brief application of alternating current stimulation reduced the effects of adaptation on single-neuron firing rates and local field potentials; this mechanistic

  18. Earth-Space Link Attenuation Estimation via Ground Radar Kdp

    Science.gov (United States)

    Bolen, Steven M.; Benjamin, Andrew L.; Chandrasekar, V.

    2003-01-01

    A method of predicting attenuation on microwave Earth/spacecraft communication links, over wide areas and under various atmospheric conditions, has been developed. In the area around the ground station locations, a nearly horizontally aimed polarimetric S-band ground radar measures the specific differential phase (Kdp) along the Earth-space path. The specific attenuation along a path of interest is then computed by use of a theoretical model of the relationship between the measured S-band specific differential phase and the specific attenuation at the frequency to be used on the communication link. The model includes effects of rain, wet ice, and other forms of precipitation. The attenuation on the path of interest is then computed by integrating the specific attenuation over the length of the path. This method can be used to determine statistics of signal degradation on Earth/spacecraft communication links. It can also be used to obtain real-time estimates of attenuation along multiple Earth/spacecraft links that are parts of a communication network operating within the radar coverage area, thereby enabling better management of the network through appropriate dynamic routing along the best combination of links.

  19. Mapping Pn amplitude spreading and attenuation in Asia

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiaoning [Los Alamos National Laboratory; Phillips, William S [Los Alamos National Laboratory; Stead, Richard J [Los Alamos National Laboratory

    2010-12-06

    Pn travels most of its path in the mantle lid. Mapping the lateral variation of Pn amplitude attenuation sheds light on material properties and dynamics of the uppermost region of the mantle. Pn amplitude variation depends on the wavefront geometric spreading as well as material attenuation. We investigated Pn geometric spreading, which is much more complex than a traditionally assumed power-law spreading model, using both synthetic and observed amplitude data collected in Asia. We derived a new Pn spreading model based on the formulation that was proposed previously to account for the spherical shape of the Earth (Yang et. al., BSSA, 2007). New parameters derived for the spreading model provide much better correction for Pn amplitudes in terms of residual behavior. Because we used observed Pn amplitudes to construct the model, the model incorporates not only the effect of the Earth's spherical shape, but also the effect of potential upper-mantle velocity gradients in the region. Using the new spreading model, we corrected Pn amplitudes measured at 1, 2, 4 and 6 Hz and conducted attenuation tomography. The resulting Pn attenuation model correlates well with the regional geology. We see high attenuation in regions such as northern Tibetan Plateau and the western Pacific subduction zone, and low attenuation for stable blocks such as Sichuan and Tarim basins.

  20. An attenuation correction method for PET/CT images

    International Nuclear Information System (INIS)

    Ue, Hidenori; Yamazaki, Tomohiro; Haneishi, Hideaki

    2006-01-01

    In PET/CT systems, accurate attenuation correction can be achieved by creating an attenuation map from an X-ray CT image. On the other hand, respiratory-gated PET acquisition is an effective method for avoiding motion blurring of the thoracic and abdominal organs caused by respiratory motion. In PET/CT systems employing respiratory-gated PET, using an X-ray CT image acquired during breath-holding for attenuation correction may have a large effect on the voxel values, especially in regions with substantial respiratory motion. In this report, we propose an attenuation correction method in which, as the first step, a set of respiratory-gated PET images is reconstructed without attenuation correction, as the second step, the motion of each phase PET image from the PET image in the same phase as the CT acquisition timing is estimated by the previously proposed method, as the third step, the CT image corresponding to each respiratory phase is generated from the original CT image by deformation according to the motion vector maps, and as the final step, attenuation correction using these CT images and reconstruction are performed. The effectiveness of the proposed method was evaluated using 4D-NCAT phantoms, and good stability of the voxel values near the diaphragm was observed. (author)

  1. A promising hybrid approach to SPECT attenuation correction

    International Nuclear Information System (INIS)

    Lewis, N.H.; Faber, T.L.; Corbett, J.R.; Stokely, E.M.

    1984-01-01

    Most methods for attenuation compensation in SPECT either rely on the assumption of uniform attenuation, or use slow iteration to achieve accuracy. However, hybrid methods that combine iteration with simple multiplicative correction can accommodate nonuniform attenuation, and such methods converge faster than other iterative techniques. The authors evaluated two such methods, which differ in use of a damping factor to control convergence. Both uniform and nonuniform attenuation were modeled, using simulated and phantom data for a rotating gamma camera. For simulations done with 360 0 data and the correct attenuation map, activity levels were reconstructed to within 5% of the correct values after one iteration. Using 180 0 data, reconstructed levels in regions representing lesion and background were within 5% of the correct values in three iterations; however, further iterations were needed to eliminate the characteristic streak artifacts. The damping factor had little effect on 360 0 reconstruction, but was needed for convergence with 180 0 data. For both cold- and hot-lesion models, image contrast was better from the hybrid methods than from the simpler geometric-mean corrector. Results from the hybrid methods were comparable to those obtained using the conjugate-gradient iterative method, but required 50-100% less reconstruction time. The relative speed of the hybrid methods, and their accuracy in reconstructing photon activity in the presence of nonuniform attenuation, make them promising tools for quantitative SPECT reconstruction

  2. Gamma-Ray Attenuation to Evaluate Soil Porosity: An Analysis of Methods

    Science.gov (United States)

    Pires, Luiz F.; Pereira, André B.

    2014-01-01

    Soil porosity (ϕ) is of a great deal for environmental studies due to the fact that water infiltrates and suffers redistribution in the soil pore space. Many physical and biochemical processes related to environmental quality occur in the soil porous system. Representative determinations of ϕ are necessary due to the importance of this physical property in several fields of natural sciences. In the current work, two methods to evaluate ϕ were analyzed by means of gamma-ray attenuation technique. The first method uses the soil attenuation approach through dry soil and saturated samples, whereas the second one utilizes the same approach but taking into account dry soil samples to assess soil bulk density and soil particle density to determine ϕ. The results obtained point out a good correlation between both methods. However, when ϕ is obtained through soil water content at saturation and a 4 mm collimator is used to collimate the gamma-ray beam the first method also shows good correlations with the traditional one. PMID:24616640

  3. Attenuation of spurious responses in electromechanical filters

    Energy Technology Data Exchange (ETDEWEB)

    Olsson, Roy H.; Hietala, Vincent M.

    2018-04-10

    A spur cancelling, electromechanical filter includes a first resonator having a first resonant frequency and one or more first spurious responses, and it also includes, electrically connected to the first resonator, a second resonator having a second resonant frequency and one or more second spurious responses. The first and second resonant frequencies are approximately identical, but the first resonator is physically non-identical to the second resonator. The difference between the resonators makes the respective spurious responses different. This allows for filters constructed from a cascade of these resonators to exhibit reduced spurious responses.

  4. Influence of different contributions of scatter and attenuation on the threshold values in contrast-based algorithms for volume segmentation.

    Science.gov (United States)

    Matheoud, Roberta; Della Monica, Patrizia; Secco, Chiara; Loi, Gianfranco; Krengli, Marco; Inglese, Eugenio; Brambilla, Marco

    2011-01-01

    The aim of this work is to evaluate the role of different amount of attenuation and scatter on FDG-PET image volume segmentation using a contrast-oriented method based on the target-to-background (TB) ratio and target dimensions. A phantom study was designed employing 3 phantom sets, which provided a clinical range of attenuation and scatter conditions, equipped with 6 spheres of different volumes (0.5-26.5 ml). The phantoms were: (1) the Hoffman 3-dimensional brain phantom, (2) a modified International Electro technical Commission (IEC) phantom with an annular ring of water bags of 3 cm thickness fit over the IEC phantom, and (3) a modified IEC phantom with an annular ring of water bags of 9 cm. The phantoms cavities were filled with a solution of FDG at 5.4 kBq/ml activity concentration, and the spheres with activity concentration ratios of about 16, 8, and 4 times the background activity concentration. Images were acquired with a Biograph 16 HI-REZ PET/CT scanner. Thresholds (TS) were determined as a percentage of the maximum intensity in the cross section area of the spheres. To reduce statistical fluctuations a nominal maximum value is calculated as the mean from all voxel > 95%. To find the TS value that yielded an area A best matching the true value, the cross section were auto-contoured in the attenuation corrected slices varying TS in step of 1%, until the area so determined differed by less than 10 mm² versus its known physical value. Multiple regression methods were used to derive an adaptive thresholding algorithm and to test its dependence on different conditions of attenuation and scatter. The errors of scatter and attenuation correction increased with increasing amount of attenuation and scatter in the phantoms. Despite these increasing inaccuracies, PET threshold segmentation algorithms resulted not influenced by the different condition of attenuation and scatter. The test of the hypothesis of coincident regression lines for the three phantoms used

  5. Attenuation correction for brain PET imaging using deep neural network based on dixon and ZTE MR images.

    Science.gov (United States)

    Gong, Kuang; Yang, Jaewon; Kim, Kyungsang; El Fakhri, Georges; Seo, Youngho; Li, Quanzheng

    2018-05-23

    Positron Emission Tomography (PET) is a functional imaging modality widely used in neuroscience studies. To obtain meaningful quantitative results from PET images, attenuation correction is necessary during image reconstruction. For PET/MR hybrid systems, PET attenuation is challenging as Magnetic Resonance (MR) images do not reflect attenuation coefficients directly. To address this issue, we present deep neural network methods to derive the continuous attenuation coefficients for brain PET imaging from MR images. With only Dixon MR images as the network input, the existing U-net structure was adopted and analysis using forty patient data sets shows it is superior than other Dixon based methods. When both Dixon and zero echo time (ZTE) images are available, we have proposed a modified U-net structure, named GroupU-net, to efficiently make use of both Dixon and ZTE information through group convolution modules when the network goes deeper. Quantitative analysis based on fourteen real patient data sets demonstrates that both network approaches can perform better than the standard methods, and the proposed network structure can further reduce the PET quantification error compared to the U-net structure. © 2018 Institute of Physics and Engineering in Medicine.

  6. Time-domain simulation of constitutive relations for nonlinear acoustics including relaxation for frequency power law attenuation media modeling

    Science.gov (United States)

    Jiménez, Noé; Camarena, Francisco; Redondo, Javier; Sánchez-Morcillo, Víctor; Konofagou, Elisa E.

    2015-10-01

    We report a numerical method for solving the constitutive relations of nonlinear acoustics, where multiple relaxation processes are included in a generalized formulation that allows the time-domain numerical solution by an explicit finite differences scheme. Thus, the proposed physical model overcomes the limitations of the one-way Khokhlov-Zabolotskaya-Kuznetsov (KZK) type models and, due to the Lagrangian density is implicitly included in the calculation, the proposed method also overcomes the limitations of Westervelt equation in complex configurations for medical ultrasound. In order to model frequency power law attenuation and dispersion, such as observed in biological media, the relaxation parameters are fitted to both exact frequency power law attenuation/dispersion media and also empirically measured attenuation of a variety of tissues that does not fit an exact power law. Finally, a computational technique based on artificial relaxation is included to correct the non-negligible numerical dispersion of the finite difference scheme, and, on the other hand, improve stability trough artificial attenuation when shock waves are present. This technique avoids the use of high-order finite-differences schemes leading to fast calculations. The present algorithm is especially suited for practical configuration where spatial discontinuities are present in the domain (e.g. axisymmetric domains or zero normal velocity boundary conditions in general). The accuracy of the method is discussed by comparing the proposed simulation solutions to one dimensional analytical and k-space numerical solutions.

  7. University physics

    CERN Document Server

    Arfken, George

    1984-01-01

    University Physics provides an authoritative treatment of physics. This book discusses the linear motion with constant acceleration; addition and subtraction of vectors; uniform circular motion and simple harmonic motion; and electrostatic energy of a charged capacitor. The behavior of materials in a non-uniform magnetic field; application of Kirchhoff's junction rule; Lorentz transformations; and Bernoulli's equation are also deliberated. This text likewise covers the speed of electromagnetic waves; origins of quantum physics; neutron activation analysis; and interference of light. This publi

  8. Ultrasonic physics

    CERN Document Server

    Richardson, E G

    1962-01-01

    Ultrasonic Physics, Second Edition, provides an introduction to the fundamental principles of ultrasonic physics. The book opens with a discussion of the sources of ultrasound. This is followed by separate chapters on the properties and detection of ultrasonic radiation; measurement of propagation constants, i.e., the velocity and absorption, of ultrasound; ultrasound propagation in gases, liquids, and solids; and ultrasound propagation in aerosols, suspensions, and emulsions. The final chapter covers miscellaneous physical and physico-chemical actions, including dispersion and coagulation of

  9. Two media method for linear attenuation coefficient determination of irregular soil samples; Metodo dos dois meios para a determinacao do coeficiente de atenuacao linear de amostras irregulares de solos

    Energy Technology Data Exchange (ETDEWEB)

    Vici, Carlos Henrique Georges

    2004-07-01

    In several situations of nuclear applications, the knowledge of gamma-ray linear attenuation coefficient for irregular samples is necessary, such as in soil physics and geology. This work presents the validation of a methodology for the determination of the linear attenuation coefficient ({mu}) of irregular shape samples, in such a way that it is not necessary to know the thickness of the considered sample. With this methodology irregular soil samples (undeformed field samples) from Londrina region, north of Parana were studied. It was employed the two media method for the {mu} determination. It consists of the {mu} determination through the measurement of a gamma-ray beam attenuation by the sample sequentially immersed in two different media, with known and appropriately chosen attenuation coefficients. For comparison, the theoretical value of {mu} was calculated by the product of the mass attenuation coefficient, obtained by the WinXcom code, and the measured value of the density sample. This software employs the chemical composition of the samples and supplies a table of the mass attenuation coefficients versus the photon energy. To verify the validity of the two media method, compared with the simple gamma ray transmission method, regular pome stone samples were used. With these results for the attenuation coefficients and their respective deviations, it was possible to compare the two methods. In this way we concluded that the two media method is a good tool for the determination of the linear attenuation coefficient of irregular materials, particularly in the study of soils samples. (author)

  10. Brunenders: a partially attenuated historic poliovirus type I vaccine strain.

    Science.gov (United States)

    Sanders, Barbara P; Liu, Ying; Brandjes, Alies; van Hoek, Vladimir; de Los Rios Oakes, Isabel; Lewis, John; Wimmer, Eckard; Custers, Jerome H H V; Schuitemaker, Hanneke; Cello, Jeronimo; Edo-Matas, Diana

    2015-09-01

    Brunenders, a type I poliovirus (PV) strain, was developed in 1952 by J. F. Enders and colleagues through serial in vitro passaging of the parental Brunhilde strain, and was reported to display partial neuroattenuation in monkeys. This phenotype of attenuation encouraged two vaccine manufacturers to adopt Brunenders as the type I component for their inactivated poliovirus vaccines (IPVs) in the 1950s, although today no licensed IPV vaccine contains Brunenders. Here we confirmed, in a transgenic mouse model, the report of Enders on the reduced neurovirulence of Brunenders. Although dramatically neuroattenuated relative to WT PV strains, Brunenders remains more virulent than the attenuated oral vaccine strain, Sabin 1. Importantly, the neuroattenuation of Brunenders does not affect in vitro growth kinetics and in vitro antigenicity, which were similar to those of Mahoney, the conventional type I IPV vaccine strain. We showed, by full nucleotide sequencing, that Brunhilde and Brunenders differ at 31 nucleotides, eight of which lead to amino acid changes, all located in the capsid. Upon exchanging the Brunenders capsid sequence with that of the Mahoney capsid, WT neurovirulence was regained in vivo, suggesting a role for the capsid mutations in Brunenders attenuation. To date, as polio eradication draws closer, the switch to using attenuated strains for IPV is actively being pursued. Brunenders preceded this novel strategy as a partially attenuated IPV strain, accompanied by decades of successful use in the field. Providing data on the attenuation of Brunenders may be of value in the further construction of attenuated PV strains to support the grand pursuit of the global eradication of poliomyelitis.

  11. Computational physics

    CERN Document Server

    Newman, Mark

    2013-01-01

    A complete introduction to the field of computational physics, with examples and exercises in the Python programming language. Computers play a central role in virtually every major physics discovery today, from astrophysics and particle physics to biophysics and condensed matter. This book explains the fundamentals of computational physics and describes in simple terms the techniques that every physicist should know, such as finite difference methods, numerical quadrature, and the fast Fourier transform. The book offers a complete introduction to the topic at the undergraduate level, and is also suitable for the advanced student or researcher who wants to learn the foundational elements of this important field.

  12. Physical Activity

    DEFF Research Database (Denmark)

    Andersen, Lars Bo; Anderssen, Sigmund Alfred; Wisløff, Ulrik

    2014-01-01

    Andersen LB, Anderssen SA, Wisløff U, Hellénius M-L, Fogelholm M, Ekelund U. (Expert Group) Nordic Nutrition Recommendations 2012. Integrating nutrition and physical activity. Chapter: Physical Activity p. 195-217.Nordic Counsil of Ministers.......Andersen LB, Anderssen SA, Wisløff U, Hellénius M-L, Fogelholm M, Ekelund U. (Expert Group) Nordic Nutrition Recommendations 2012. Integrating nutrition and physical activity. Chapter: Physical Activity p. 195-217.Nordic Counsil of Ministers....

  13. Attenuation of trace organic compounds (TOrCs) inbioelectrochemical systems

    KAUST Repository

    Werner, Craig M.

    2015-04-01

    Microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) are two types of microbial bioelectrochemical systems (BESs) that use microorganisms to convert chemical energy in wastewaters into useful energy products such as (bio)electricity (MFC) or hydrogen gas (MEC). These two systems were evaluated for their capacity to attenuate trace organic compounds (TOrCs), commonly found in municipal wastewater, under closed circuit (current generation) and open circuit (no current generation) conditions, using acetate as the carbon source. A biocide was used to evaluate attenuation in terms of biotransformation versus sorption. The difference in attenuation observed before and after addition of the biocide represented biotransformation, while attenuation after addition of a biocide primarily indicated sorption. Attenuation of TOrCs was similar in MFCs and MECs for eight different TOrCs, except for caffeine and trimethoprim where slightly higher attenuation was observed in MECs. Electric current generation did not enhance attenuation of the TOrCs except for caffeine, which showed slightly higher attenuation under closed circuit conditions in both MFCs and MECs. Substantial sorption of the TOrCs occurred to the biofilm-covered electrodes, but no consistent trend could be identified regarding the physico-chemical properties of the TOrCs tested and the extent of sorption. The octanol-water distribution coefficient at pH 7.4 (log DpH 7.4) appeared to be a reasonable predictor for sorption of some of the compounds (carbamazepine, atrazine, tris(2-chloroethyl) phosphate and diphenhydramine) but not for others (N,N-Diethyl-meta-toluamide). Atenolol also showed high levels of sorption despite being the most hydrophilic in the suite of compounds studied (log DpH 7.4=-1.99). Though BESs do not show any inherent advantages over conventional wastewater treatment, with respect to TOrC removal, overall removals in BESs are similar to that reported for conventional wastewater

  14. Segmented attenuation correction using artificial neural networks in positron tomography

    International Nuclear Information System (INIS)

    Yu, S.K.; Nahmias, C.

    1996-01-01

    The measured attenuation correction technique is widely used in cardiac positron tomographic studies. However, the success of this technique is limited because of insufficient counting statistics achievable in practical transmission scan times, and of the scattered radiation in transmission measurement which leads to an underestimation of the attenuation coefficients. In this work, a segmented attenuation correction technique has been developed that uses artificial neural networks. The technique has been validated in phantoms and verified in human studies. The results indicate that attenuation coefficients measured in the segmented transmission image are accurate and reproducible. Activity concentrations measured in the reconstructed emission image can also be recovered accurately using this new technique. The accuracy of the technique is subject independent and insensitive to scatter contamination in the transmission data. This technique has the potential of reducing the transmission scan time, and satisfactory results are obtained if the transmission data contain about 400 000 true counts per plane. It can predict accurately the value of any attenuation coefficient in the range from air to water in a transmission image with or without scatter correction. (author)

  15. Radiation induced time dependent attenuation in a fiber

    International Nuclear Information System (INIS)

    Kelly, R.E.; Lyons, P.B.; Looney, L.D.

    1985-01-01

    Characteristics describing the time dependent attenuation coefficient of an optical fiber during and following a very short and intense radiation pulse are analyzed. This problem is important for transmission applications when the fiber is subjected to gamma, electron, or neutron beams. Besides time, the attenuation coefficient is a function of temperature, dose rate, dose, nature of the radiation (n, e, γ), fiber composition and purity, pre-existing solid state defects, and wavelength of the transmitted signal. The peak attenuation for a given fiber is mainly determined by the dose rate and pulse length, but temperature and strain (or athermal) annealing also contribute to a partial recovery during the pulse duration. The peak attenuation per unit dose appears to be smaller at high doses, perhaps caused by particle track overlap, which produces a saturation effect. After pulse termination, the attenuation coefficient tends to recover towards its pre-radiation value at different rates, depending upon the factors mentioned above. In particular, ionized electrons relax back to the positive lattice ions at a rate which depends upon initial separation distance and temperature. The initial separation distance is a function of beam energy. Some electrons will encounter a trap in the lattice and may recombine by quantum mechanical tunneling or be removed by photons (hence, absorption). Besides ionization, radiation may induce lattice displacements which in turn produce additional absorption centers. The displacement contribution has a different time constant than that associated with ionization. These topics, as they influence fiber characteristics, are discussed, along with supporting experimental data

  16. Pentoxifylline Attenuates Cardiac Remodeling Induced by Tobacco Smoke Exposure

    Energy Technology Data Exchange (ETDEWEB)

    Minicucci, Marcos; Oliveira, Fernando; Santos, Priscila; Polegato, Bertha; Roscani, Meliza; Fernandes, Ana Angelica; Lustosa, Beatriz; Paiva, Sergio; Zornoff, Leonardo; Azevedo, Paula, E-mail: paulasa@fmb.unesp.br [Faculdade de Medicina de Botucatu, Universidade Estadual Paulista, São Paulo, SP (Brazil)

    2016-05-15

    Tobacco smoke exposure is an important risk factor for cardiac remodeling. Under this condition, inflammation, oxidative stress, energy metabolism abnormalities, apoptosis, and hypertrophy are present. Pentoxifylline has anti‑inflammatory, anti-apoptotic, anti-thrombotic and anti-proliferative properties. The present study tested the hypothesis that pentoxifylline would attenuate cardiac remodeling induced by smoking. Wistar rats were distributed in four groups: Control (C), Pentoxifylline (PX), Tobacco Smoke (TS), and PX-TS. After two months, echocardiography, invasive blood pressure measurement, biochemical, and histological studies were performed. The groups were compared by two-way ANOVA with a significance level of 5%. TS increased left atrium diameter and area, which was attenuated by PX. In the isolated heart study, TS lowered the positive derivate (+dp/dt), and this was attenuated by PX. The antioxidants enzyme superoxide dismutase and glutathione peroxidase were decreased in the TS group; PX recovered these activities. TS increased lactate dehydrogenase (LDH) and decreased 3-hydroxyacyl Coenzyme A dehydrogenases (OH-DHA) and citrate synthase (CS). PX attenuated LDH, 3-OH-DHA and CS alterations in TS-PX group. TS increased IL-10, ICAM-1, and caspase-3. PX did not influence these variables. TS induced cardiac remodeling, associated with increased inflammation, oxidative stress, apoptosis, and changed energy metabolism. PX attenuated cardiac remodeling by reducing oxidative stress and improving cardiac bioenergetics, but did not act upon cardiac cytokines and apoptosis.

  17. A practical attenuation compensation method for cone beam spect

    International Nuclear Information System (INIS)

    Manglos, S.H.; Jaszczak, R.J.; Floyd, C.E.; Greer, K.L.; Coleman, R.E.

    1987-01-01

    An algorithm for attenuation compensation of cone beam SPECT images has been developed and implemented. The algorithm is based on a multiplicative post-processing method previously used for parallel and fan beam geometries. This method computes the compensation from the estimated average attenuation of photons originating from each image pixel. In the present development, a uniform attenuation coefficient inside of the body contour is assumed, although the method could be extended to include a non-uniform attenuation map. The algorithm is tested with experimental projections of a phantom obtained using a cone beam collimator. Profiles through the reconstructed images are presented as a quantitative test of the improvement due to the compensation. The algorithm provides adequate compensation for attenuation in a simple uniform cylindrical phantom, and the computational time is short compared to that expected for iterative reconstruction techniques. Also observed are image distortions in some reconstructed slices when the source distribution extends beyond the edge of the cone beam axial field-of-view

  18. Wild type measles virus attenuation independent of type I IFN

    Directory of Open Access Journals (Sweden)

    Horvat Branka

    2008-02-01

    Full Text Available Abstract Background Measles virus attenuation has been historically performed by adaptation to cell culture. The current dogma is that attenuated virus strains induce more type I IFN and are more resistant to IFN-induced protection than wild type (wt. Results The adaptation of a measles virus isolate (G954-PBL by 13 passages in Vero cells induced a strong attenuation of this strain in vivo. The adapted virus (G954-V13 differs from its parental strain by only 5 amino acids (4 in P/V/C and 1 in the M gene. While a vaccine strain, Edmonston Zagreb, could replicate equally well in various primate cells, both G954 strains exhibited restriction to the specific cell type used initially for their propagation. Surprisingly, we observed that both G954 strains induced type I IFN, the wt strain inducing even more than the attenuated ones, particularly in human plasmacytoid Dendritic Cells. Type I IFN-induced protection from the infection of both G954 strains depended on the cell type analyzed, being less efficient in the cells used to grow the viral strain. Conclusion Thus, mutations in M and P/V/C proteins can critically affect MV pathogenicity, cellular tropism and lead to virus attenuation without interfering with the α/β IFN system.

  19. Principles underlying rational design of live attenuated influenza vaccines

    Science.gov (United States)

    Jang, Yo Han

    2012-01-01

    Despite recent innovative advances in molecular virology and the developments of vaccines, influenza virus remains a serious burden for human health. Vaccination has been considered a primary countermeasure for prevention of influenza infection. Live attenuated influenza vaccines (LAIVs) are particularly attracting attention as an effective strategy due to several advantages over inactivated vaccines. Cold-adaptation, as a classical means for attenuating viral virulence, has been successfully used for generating safe and effective donor strains of LAIVs against seasonal epidemics and occasional pandemics. Recently, the advent of reverse genetics technique expedited a variety of rational strategies to broaden the pool of LAIVs. Considering the breadth of antigenic diversity of influenza virus, the pool of LAIVs is likely to equip us with better options for controlling influenza pandemics. With a brief reflection on classical attenuating strategies used at the initial stage of development of LAIVs, especially on the principles underlying the development of cold-adapted LAIVs, we further discuss and outline other attenuation strategies especially with respect to the rationales for attenuation, and their practicality for mass production. Finally, we propose important considerations for a rational vaccine design, which will provide us with practical guidelines for improving the safety and effectiveness of LAIVs. PMID:23596576

  20. Semiconductor physics

    CERN Document Server

    Böer, Karl W

    2018-01-01

    This handbook gives a complete survey of the important topics and results in semiconductor physics. It addresses every fundamental principle and most research topics and areas of application in the field of semiconductor physics. Comprehensive information is provided on crystalline bulk and low-dimensional as well as amporphous semiconductors, including optical, transport, and dynamic properties.

  1. Radiotherapy physics

    International Nuclear Information System (INIS)

    Chen, G.T.Y.; Collier, J.M.; Lyman, J.T.; Pitluck, S.

    1982-01-01

    The Radiotherapy Physics Group works on the physical and biophysical aspects of charged particle radiotherapy. Our activities include the development of isosurvival beams (beams of uniform biological effect), computerized treatment planning development for charged particle radiotherapy, design of compensation to shape dose distributions, and development of dosimetry techniques to verify planned irradiations in both phantoms and patients

  2. Atomic physics

    International Nuclear Information System (INIS)

    Held, B.

    1991-01-01

    This general book describes the change from classical physics to quantum physics. The first part presents atom evolution since antiquity and introduces fundamental quantities and elements of relativity. Experiments which have contributed to the evolution of knowledge on matter are analyzed in the second part. Applications of wave mechanics to the study of matter properties are presented in the third part [fr

  3. Reactor physics

    International Nuclear Information System (INIS)

    Ait Abderrahim, H.

    1998-01-01

    Progress in research on reactor physics in 1997 at the Belgian Nuclear Research Centre SCK/CEN is described. Activities in the following four domains are discussed: core physics, ex-core neutron transport, experiments in Materials Testing Reactors, international benchmarks

  4. Imagined Physics

    DEFF Research Database (Denmark)

    Merritt, Timothy Robert; Nørgaard, M.; Laursen, C.

    2015-01-01

    to this book focuses on the human responses to objects that change shape in response to input from users, environment, or other circumstances. In this chapter we discuss the term "imagined physics", meaning how actuated devices are in one sense tied to their physical form, yet through the use of actuators...

  5. Understanding physics

    CERN Document Server

    Cassidy, David; Rutherford, James

    2002-01-01

    Understanding Physics provides a thorough grounding in contemporary physics while placing physics into its social and historical context Based in large part on the highly respected Project Physics Course developed by two of the authors, it also integrates the results of recent pedagogical research The text thus - teaches about the basic phenomena in the physical world and the concepts developed to explain them - shows that science is a rational human endeavor with a long and continuing tradition, involving many different cultures and people - develops facility in critical thinking, reasoned argumentation, evaluation of evidence, mathematical modeling, and ethical values The treatment emphasizes not only what we know but also how we know it, why we believe it, and what effects that knowledge has - Why do we believe the Earth and planets revolve around the Sun? - Why do we believe that matter is made of atoms? - How do relativity theory and quantum mechanics alter our conception of Nature and in what ways do th...

  6. Development of a human live attenuated West Nile infectious DNA vaccine: Suitability of attenuating mutations found in SA14-14-2 for WN vaccine design

    Energy Technology Data Exchange (ETDEWEB)

    Yamshchikov, Vladimir, E-mail: yaximik@gmail.com; Manuvakhova, Marina; Rodriguez, Efrain

    2016-01-15

    Direct attenuation of West Nile (WN) virus strain NY99 for the purpose of vaccine development is not feasible due to its high virulence and pathogenicity. Instead, we created highly attenuated chimeric virus W1806 with the serological identity of NY99. To further attenuate W1806, we investigated effects of mutations found in Japanese encephalitis virus vaccine SA14-14-2. WN viruses carrying all attenuating mutations lost infectivity in mammalian, but not in mosquito cells. No single reversion restored infectivity in mammalian cells, although increased infectivity in mosquito cells was observed. To identify a subset of mutations suitable for further attenuation of W1806, we analyzed effects of E{sub 138}K and K{sub 279}M changes on virulence, growth properties, and immunogenicity of derivatized W956, from which chimeric W1806 inherited its biological properties and attenuation profile. Despite strong dominant attenuating effect, introduction of only two mutations was not sufficient for attenuating W1806 to the safety level acceptable for human use. - Highlights: • Further attenuation of a WN vaccine precursor is outlined. • Effect of SA14-14-2 attenuating mutations is tested. • Mechanism of attenuation is proposed and illustrated. • The need for additional attenuating mutations is justified.

  7. Attenuation correction method for single photon emission CT

    Energy Technology Data Exchange (ETDEWEB)

    Morozumi, Tatsuru; Nakajima, Masato [Keio Univ., Yokohama (Japan). Faculty of Science and Technology; Ogawa, Koichi; Yuta, Shinichi

    1983-10-01

    A correction method (Modified Correction Matrix method) is proposed to implement iterative correction by exactly measuring attenuation constant distribution in a test body, calculating a correction factor for every picture element, then multiply the image by these factors. Computer simulation for the comparison of the results showed that the proposed method was specifically more effective to an application to the test body, in which the rate of attenuation constant change is large, than the conventional correction matrix method. Since the actual measurement data always contain quantum noise, the noise was taken into account in the simulation. However, the correction effect was large even under the noise. For verifying its clinical effectiveness, the experiment using an acrylic phantom was also carried out. As the result, the recovery of image quality in the parts with small attenuation constant was remarkable as compared with the conventional method.

  8. Development of electrothermal actuation based planar variable optical attenuators (VOAs)

    International Nuclear Information System (INIS)

    Lee, Chengkuo; Yeh, J Andrew

    2006-01-01

    Several sorts of MEMS (Microelectromechanical Systems) based have been demonstrated by using electrostatic actuation scheme up to date. The comb drive and parallel plate are the two most common electrostatic actuators that have been well studied in variable optical attenuator (VOA) applications. In addition to the known retro-reflection type of optical attenuation being realized by our new devices driven by electrothermal actuators in present study, a novel planar tilted mirror with rotational and translation moving capability is proposed by using electrothermal actuators as well. Using electrothermal actuators to provide said planar tilted mirror with rotational and translational displacement has granted us a more efficient way to perform the light attenuation for in-plane structure. The static and transient characteristics of devices operated at ambient room temperature environment show good repeatability and stability

  9. Determination of Dimensionless Attenuation Coefficient in Shaped Resonators

    Science.gov (United States)

    Daniels, C.; Steinetz, B.; Finkbeiner, J.; Raman, G.; Li, X.

    2003-01-01

    The value of dimensionless attenuation coefficient is an important factor when numerically predicting high-amplitude acoustic waves in shaped resonators. Both the magnitude of the pressure waveform and the quality factor rely heavily on this dimensionless parameter. Previous authors have stated the values used, but have not completely explained their methods. This work fully describes the methodology used to determine this important parameter. Over a range of frequencies encompassing the fundamental resonance, the pressure waves were experimentally measured at each end of the shaped resonators. At the corresponding dimensionless acceleration, the numerical code modeled the acoustic waveforms generated in the resonator using various dimensionless attenuation coefficients. The dimensionless attenuation coefficient that most closely matched the pressure amplitudes and quality factors of the experimental and numerical results was determined to be the value to be used in subsequent studies.

  10. Iterative methods for photoacoustic tomography in attenuating acoustic media

    Science.gov (United States)

    Haltmeier, Markus; Kowar, Richard; Nguyen, Linh V.

    2017-11-01

    The development of efficient and accurate reconstruction methods is an important aspect of tomographic imaging. In this article, we address this issue for photoacoustic tomography. To this aim, we use models for acoustic wave propagation accounting for frequency dependent attenuation according to a wide class of attenuation laws that may include memory. We formulate the inverse problem of photoacoustic tomography in attenuating medium as an ill-posed operator equation in a Hilbert space framework that is tackled by iterative regularization methods. Our approach comes with a clear convergence analysis. For that purpose we derive explicit expressions for the adjoint problem that can efficiently be implemented. In contrast to time reversal, the employed adjoint wave equation is again damping and, thus has a stable solution. This stability property can be clearly seen in our numerical results. Moreover, the presented numerical results clearly demonstrate the efficiency and accuracy of the derived iterative reconstruction algorithms in various situations including the limited view case.

  11. Ultrasonic attenuation of CdSe at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, B.J., E-mail: braulio@ula.v [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes Apartado de Correos No.1, La Hechicera, Merida 5251 (Venezuela, Bolivarian Republic of); Calderon, E.; Bracho, D.B. [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes Apartado de Correos No.1, La Hechicera, Merida 5251 (Venezuela, Bolivarian Republic of); Perez, J.F. [Laboratorio de Instrumentacion Cientifica, Facultad de Ciencias, Universidad de Los Andes Apartado de Correos No.1, La Hechicera, Merida 5251 (Venezuela, Bolivarian Republic of)

    2010-08-01

    The ultrasonic attenuation of a single crystal of CdSe has been investigated over the temperature range from 1.2 to 300 K at frequencies of 10, 30 and 90 MHz. We report here the temperature dependence of the attenuation in the range 1.2-30 K for piezoactive and non-piezoactive acoustic waves. A temperature-induced relaxation for two piezoactive waves, which scale with frequency towards higher temperatures, was found. A modified Hutson and White model with a new parameter {gamma} is proposed to explain the relaxation maxima of our data and others in the literature. In this model the parameter {gamma}, which seems to be closely related to the compensation, takes into account the impurities-sound wave piezoelectric coupling. By inverting the proposed expression for the sound attenuation to obtain the electrical conductivity from the relaxation, it is found that impurity conductivity of the hopping type is the dominant conduction process at low temperatures.

  12. Ultrasonic attenuation of CdSe at low temperatures

    International Nuclear Information System (INIS)

    Fernandez, B.J.; Calderon, E.; Bracho, D.B.; Perez, J.F.

    2010-01-01

    The ultrasonic attenuation of a single crystal of CdSe has been investigated over the temperature range from 1.2 to 300 K at frequencies of 10, 30 and 90 MHz. We report here the temperature dependence of the attenuation in the range 1.2-30 K for piezoactive and non-piezoactive acoustic waves. A temperature-induced relaxation for two piezoactive waves, which scale with frequency towards higher temperatures, was found. A modified Hutson and White model with a new parameter γ is proposed to explain the relaxation maxima of our data and others in the literature. In this model the parameter γ, which seems to be closely related to the compensation, takes into account the impurities-sound wave piezoelectric coupling. By inverting the proposed expression for the sound attenuation to obtain the electrical conductivity from the relaxation, it is found that impurity conductivity of the hopping type is the dominant conduction process at low temperatures.

  13. Consideration of natural attenuation. In remedation contaminated sites

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-04-15

    Upon the proposal submitted by ist Standing committee 5 (Contaminated Sites Committee - ALA) the Federal / State Working Group on Soil protection employed an ad hoc subcommittee dealing with considering natural attenuation in remediating contaminated sites and preparing an inter-State position paper. In the present position paper the way how to consider natural attenuation in practical remediation of contaminated sites is described. The systematic approach outlined allows an understandable decision-finding. A way is shown how the competent soil protection authorities may exercise discretion and in the framework of checking the appropriateness of measures may decide on the implementation of MNA based on a MNA concept (MNA = monitored natural attenuation). It is, however, also explained that when carrying out MNA a decision always made in an individual case is concerned which should be made in a close agreement between the obligated party and the authority.

  14. Fast neutron attenuation measurements for detection of illicit materials

    International Nuclear Information System (INIS)

    Lee, Hee Seock; Chung, Chin Wha; Guon, Ki Il; Lee, Bo Young; Ko, Seung Kook; Shin, Yong Mu

    2002-01-01

    Experiments were carried out to develop a novel method using neutron attenuation for the detection of illicit materials. By using pulsed fast neutrons generated from a Bi target bombarded with a 2 GeV electron beam, attenuation spectra of C, N, and O have been measured to study the feasibility of a practical application. The spectral dependence on the material thickness and the geometrical distribution as well as the ability to identify different elements in a layered environment have been studied. For the elements mentioned here, the total cross sections have been obtained from the measured attenuation spectra and compared with ENDF-VI, which showed good agreement. The study confirms that a conventional low energy electron linac can be put into a practical use, and some practical idea is presented

  15. The frequency attenuation effect in identity and associative priming.

    Science.gov (United States)

    Nievas, Francisco

    2010-05-01

    Three lexical decision experiments were carried out, where the masked priming paradigm is used to study the role of the frequency attenuation effect (more priming in low-frequency target words than in high-frequency target words) in repetition and associative priming, manipulating Prime Duration (PD) and Stimulus Onset Asynchrony (SOA). A new concept was introduced, Minimum Time Threshold (MTT), this is, the minimum time interval of exposure to the masked word in order to become aware of it. Results support the notion that MTT is a key to the appearance of the frequency attenuation effect when enough word processing time is allowed. Results do not support the unified explanation of masked priming and long-term priming as proposed by Bodner and Masson (2001). Moreover, information feedback from the semantic level was not the reason for the frequency attenuation effect in repetition priming.

  16. TEACHING PHYSICS: Teaching particle physics

    Science.gov (United States)

    Hanley, Phil

    2000-09-01

    Particle physics attracts many students who hear of news from CERN or elsewhere in the media. This article examines which current A-level syllabuses include which bits of particle physics and surveys the many different types of resource available to teachers and students.

  17. Remediation of groundwater contaminated with arsenic through enhanced natural attenuation: Batch and column studies.

    Science.gov (United States)

    Hafeznezami, Saeedreza; Zimmer-Faust, Amity G; Jun, Dukwoo; Rugh, Megyn B; Haro, Heather L; Park, Austin; Suh, Jae; Najm, Tina; Reynolds, Matthew D; Davis, James A; Parhizkar, Tarannom; Jay, Jennifer A

    2017-10-01

    Batch and column laboratory experiments were conducted on natural sediment and groundwater samples from a contaminated site in Maine, USA with the aim of lowering the dissolved arsenate [As(V)] concentrations through chemical enhancement of natural attenuation capacity. In batch factorial experiments, two levels of treatment for three parameters (pH, Ca, and Fe) were studied at different levels of phosphate to evaluate their impact on As(V) solubility. Results illustrated that lowering pH, adding Ca, and adding Fe significantly increased the sorption capacity of sediments. Overall, Fe amendment had the highest individual impact on As(V) levels. To provide further evidence for the positive impact of Ca on As(V) adsorption, isotherm experiments were conducted at three different levels of Ca concentrations. A consistent increase in adsorption capacity (26-37%) of sediments was observed with the addition of Ca. The observed favorable effect of Ca on As(V) adsorption is likely caused by an increase in the surface positive charges due to surface accumulation of Ca 2+ ions. Column experiments were conducted by flowing contaminated groundwater with elevated pH, As(V), and phosphate through both uncontaminated and contaminated sediments. Potential in-situ remediation scenarios were simulated by adding a chemical amendment feed to the columns injecting Fe(II) or Ca as well as simultaneous pH adjustment. Results showed a temporary and limited decrease in As(V) concentrations under the Ca treatment (39-41%) and higher levels of attenuation in Fe(II) treated columns (50-91%) but only after a certain number of pore volumes (18-20). This study illustrates the importance of considering geochemical parameters including pH, redox potential, presence of competing ions, and sediment chemical and physical characteristics when considering enhancing the natural attenuation capacity of sediments to mitigate As contamination in natural systems. Copyright © 2017 Elsevier Ltd. All rights

  18. Simultaneous correction of attenuation and geometric response in emission tomography applied to nuclear waste drums

    International Nuclear Information System (INIS)

    Thierry, Raphael

    1999-01-01

    Multi-photonic emission tomography is a non destructive technique applied to the control of radioactive waste drums. The emitted gamma rays are detected on the range [50 keV, 2 MeV] by a hyper pure germanium, of high resolution in energy, which enables to set up a detailed list of radionuclides contained within the drum. From different points of measurement located in a transaxial plane of the drum, the activity distribution is computed by a reconstruction algorithm. An algebraic modelling of the physical process has been developed in order to correct the different degrading phenomenon, in particular the attenuation and the detector geometric response. Attenuation through the materials constituting the barrel is the preponderant phenomena. Its ignorance prevents from accurate activity quantification. Its correction has been realised from an attenuation map obtained by a transmission tomograph. The detector geometric response, introducing a blurring within the detection, is compensated by an analytic model. An adequate modelling of those phenomenon is primordial: it highly contributes on a large scale the image quality and the quantification. The image reconstruction, requiring the resolution of sparse linear system, is realised by iterative algorithms. Due to the 'ill-posed' nature of tomographic reconstruction, it is necessary to use regularisation: by introducing an a priori information on the solution, the stabilisation of the methods is carried out. We chose to minimise the Maximum A Posteriori criterion. Its resolution is considered with a half-quadratic regularisation: it permits the preservation of natural discontinuities, and avoids global-over smoothing of the image. It is evaluated on real phantoms and waste drums. Efficient sampling of the data is considered. (author) [fr

  19. A method for estimating the diffuse attenuation coefficient (KdPAR)from paired temperature sensors

    Science.gov (United States)

    Read, Jordan S.; Rose, Kevin C.; Winslow, Luke A.; Read, Emily K.

    2015-01-01

    A new method for estimating the diffuse attenuation coefficient for photosynthetically active radiation (KdPAR) from paired temperature sensors was derived. We show that during cases where the attenuation of penetrating shortwave solar radiation is the dominant source of temperature changes, time series measurements of water temperatures at multiple depths (z1 and z2) are related to one another by a linear scaling factor (a). KdPAR can then be estimated by the simple equation KdPAR ln(a)/(z2/z1). A suggested workflow is presented that outlines procedures for calculating KdPAR according to this paired temperature sensor (PTS) method. This method is best suited for conditions when radiative temperature gains are large relative to physical noise. These conditions occur frequently on water bodies with low wind and/or high KdPARs but can be used for other types of lakes during time periods of low wind and/or where spatially redundant measurements of temperatures are available. The optimal vertical placement of temperature sensors according to a priori knowledge of KdPAR is also described. This information can be used to inform the design of future sensor deployments using the PTS method or for campaigns where characterizing sub-daily changes in temperatures is important. The PTS method provides a novel method to characterize light attenuation in aquatic ecosystems without expensive radiometric equipment or the user subjectivity inherent in Secchi depth measurements. This method also can enable the estimation of KdPAR at higher frequencies than many manual monitoring programs allow.

  20. Interpreting Physics

    CERN Document Server

    MacKinnon, Edward

    2012-01-01

    This book is the first to offer a systematic account of the role of language in the development and interpretation of physics. An historical-conceptual analysis of the co-evolution of mathematical and physical concepts leads to the classical/quatum interface. Bohrian orthodoxy stresses the indispensability of classical concepts and the functional role of mathematics. This book analyses ways of extending, and then going beyond this orthodoxy orthodoxy. Finally, the book analyzes how a revised interpretation of physics impacts on basic philosophical issues: conceptual revolutions, realism, and r

  1. Statistical Physics

    CERN Document Server

    Wannier, Gregory Hugh

    1966-01-01

    Until recently, the field of statistical physics was traditionally taught as three separate subjects: thermodynamics, statistical mechanics, and kinetic theory. This text, a forerunner in its field and now a classic, was the first to recognize the outdated reasons for their separation and to combine the essentials of the three subjects into one unified presentation of thermal physics. It has been widely adopted in graduate and advanced undergraduate courses, and is recommended throughout the field as an indispensable aid to the independent study and research of statistical physics.Designed for

  2. Computational physics

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1987-01-15

    Computers have for many years played a vital role in the acquisition and treatment of experimental data, but they have more recently taken up a much more extended role in physics research. The numerical and algebraic calculations now performed on modern computers make it possible to explore consequences of basic theories in a way which goes beyond the limits of both analytic insight and experimental investigation. This was brought out clearly at the Conference on Perspectives in Computational Physics, held at the International Centre for Theoretical Physics, Trieste, Italy, from 29-31 October.

  3. Higgs Physics

    CERN Document Server

    Grojean, C.

    2016-01-01

    The cause of the screening of the weak interactions at long distances puzzled the high-energy community for more nearly half a century. With the discovery of the Higgs boson a new era started with direct experimental information on the physics behind the breaking of the electroweak symmetry. This breaking plays a fundamental role in our understanding of particle physics and sits at the high-energy frontier beyond which we expect new physics that supersedes the Standard Model. The Higgs boson (inclusive and differential) production and decay rates offer a new way to probe this frontier.

  4. Atomic physics

    CERN Document Server

    Foot, Christopher J

    2007-01-01

    This text will thoroughly update the existing literature on atomic physics. Intended to accompany an advanced undergraduate course in atomic physics, the book will lead the students up to the latest advances and the applications to Bose-Einstein Condensation of atoms, matter-wave inter-ferometry and quantum computing with trapped ions. The elementary atomic physics covered in the early chapters should be accessible to undergraduates when they are first introduced to the subject. To complement. the usual quantum mechanical treatment of atomic structure the book strongly emphasizes the experimen

  5. Plasma physics

    CERN Document Server

    Drummond, James E

    1961-01-01

    A historic snapshot of the field of plasma physics, this fifty-year-old volume offers an edited collection of papers by pioneering experts in the field. In addition to assisting students in their understanding of the foundations of classical plasma physics, it provides a source of historic context for modern physicists. Highly successful upon its initial publication, this book was the standard text on plasma physics throughout the 1960s and 70s.Hailed by Science magazine as a ""well executed venture,"" the three-part treatment ranges from basic plasma theory to magnetohydrodynamics and microwa

  6. Computational physics

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    Computers have for many years played a vital role in the acquisition and treatment of experimental data, but they have more recently taken up a much more extended role in physics research. The numerical and algebraic calculations now performed on modern computers make it possible to explore consequences of basic theories in a way which goes beyond the limits of both analytic insight and experimental investigation. This was brought out clearly at the Conference on Perspectives in Computational Physics, held at the International Centre for Theoretical Physics, Trieste, Italy, from 29-31 October

  7. Neutrino physics

    CERN Document Server

    Hernandez, P.

    2016-01-01

    This is the writeup of the lectures on neutrino physics delivered at various schools: TASI and Trieste in 2013 and the CERN-Latin American School in 2015. The topics discussed in this lecture include: general properties of neutrinos in the SM, the theory of neutrino masses and mixings (Dirac and Majorana), neutrino oscillations both in vacuum and in matter, as well as an overview of the experimental evidence for neutrino masses and of the prospects in neutrino oscillation physics. We also briefly review the relevance of neutri- nos in leptogenesis and in beyond-the-Standard-Model physics.

  8. Laser physics

    CERN Document Server

    Milonni, Peter W

    2010-01-01

    Create physically realistic 3D Graphics environments with this introduction to the ideas and techniques behind the process. Author David H. Eberly includes simulations to introduce the key problems involved and then gradually reveals the mathematical and physical concepts needed to solve them. He then describes all the algorithmic foundations and uses code examples and working source code to show how they are implemented, culminating in a large collection of physical simulations. The book tackles the complex, challenging issues that other books avoid, including Lagrangian dynamics, rigid body

  9. Rock Physics

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke

    2017-01-01

    Rock physics is the discipline linking petrophysical properties as derived from borehole data to surface based geophysical exploration data. It can involve interpretation of both elastic wave propagation and electrical conductivity, but in this chapter focus is on elasticity. Rock physics is based...... on continuum mechanics, and the theory of elasticity developed for statics becomes the key to petrophysical interpretation of velocity of elastic waves. In practice, rock physics involves interpretation of well logs including vertical seismic profiling (VSP) and analysis of core samples. The results...

  10. Performance of composites made with polymers of silicone rubber and waste of lead on the properties of attenuation

    International Nuclear Information System (INIS)

    Barros, Frieda S.; Paredes, Ramon S.C.

    2009-01-01

    All facilities and personnel protection equipment which use ionizing radiation need protection. Based on this statement, several researchers have aimed their projects searching for new materials that present good behavior facing the attenuation properties. This research aims at the development of a composite by using the silicon rubber associated to the residue of lead in powder, obtained via the recycling of components of lead from automobile batteries. In this work , were checked the morphological physical - chemical properties of the materials isolated and associated, the calorimetrical properties of the performance of the composite related to the attenuation for X-Rays and gamma, through experimental rehearsals and computational simulation. For mixtures with 40% of lead residue, referential value in mass, favorable results were obtained about armor. In this way, it was allied the good performance of the composite with a reduction of an environmental passive to the process of recycling lead. (author)

  11. Note: Attenuation motion of acoustically levitated spherical rotor

    Science.gov (United States)

    Lü, P.; Hong, Z. Y.; Yin, J. F.; Yan, N.; Zhai, W.; Wang, H. P.

    2016-11-01

    Here we observe the attenuation motion of spherical rotors levitated by near-field acoustic radiation force and analyze the factors that affect the duration time of free rotation. It is found that the rotating speed of freely rotating rotor decreases exponentially with respect to time. The time constant of exponential attenuation motion depends mainly on the levitation height, the mass of rotor, and the depth of concave ultrasound emitter. Large levitation height, large mass of rotor, and small depth of concave emitter are beneficial to increase the time constant and hence extend the duration time of free rotation.

  12. Viscosity and attenuation of sound wave in high density deuterium

    International Nuclear Information System (INIS)

    Inoue, Kazuko; Ariyasu, Tomio

    1985-01-01

    The penetration of low frequency sound wave into the fuel deuterium is discussed as for laser fusion. The sound velocity and the attenuation constant due to viscosity are calculated for high density (n = 10 24 -- 10 27 cm -3 , T = 10 -1 -- 10 4 eV) deuterium. The shear viscosity of free electron gas and the bulk viscosity due to ion-ion interaction mainly contribute to the attenuation of sound wave. The sound wave of the frequency below 10 10 Hz can easily penetrate through the compressed fuel deuterium of diameter 1 -- 10 3 μm. (author)

  13. Ultrasonic attenuation measurements and 'glassy' behaviour of neutron irradiated quartz

    International Nuclear Information System (INIS)

    Laermans, C.; Esteves, V.; Vanelstraete, A.

    1986-01-01

    The ultrasonic attenuation of longitudinal acoustic waves in slightly disordered crystalline quartz has been measured over a temperature range from 1.3 to 300 K, using the pulse-echo technique. Neutron irradiation is demonstrated to increase the ultrasonic attenuation at low temperatures indicating the presence of two-level tunneling systems similar to those of glasses. The present low-temperature acoustic results agree with a frequency independence and a T 3 behaviour for the relaxation process predicted by the two-level tunneling TLS-model where the regime ωT 1 >> 1 holds. (author)

  14. Prediction of slant path rain attenuation statistics at various locations

    Science.gov (United States)

    Goldhirsh, J.

    1977-01-01

    The paper describes a method for predicting slant path attenuation statistics at arbitrary locations for variable frequencies and path elevation angles. The method involves the use of median reflectivity factor-height profiles measured with radar as well as the use of long-term point rain rate data and assumed or measured drop size distributions. The attenuation coefficient due to cloud liquid water in the presence of rain is also considered. Absolute probability fade distributions are compared for eight cases: Maryland (15 GHz), Texas (30 GHz), Slough, England (19 and 37 GHz), Fayetteville, North Carolina (13 and 18 GHz), and Cambridge, Massachusetts (13 and 18 GHz).

  15. Measurement of linear attenuation coefficient of different materials

    International Nuclear Information System (INIS)

    Ali, M. M.

    2013-07-01

    In this research we study the linear attenuation coefficient from the materials concrete, brick, mixture concrete and iron. In the secondary standard dosimetry laboratory in Atomic Energy from different distance by use Cs-137 sours, chamber farmer 2675 A-600 cc-S/N 0511, and electrometer 2670 A-S/N 114. Found the value of linear attenuation coefficient of concert in the range 0.167 cm -1 , the brick in the range 0.063 -1 and mixture concrete and iron in the range 0.253cm -1 .(Author)

  16. Radiation-induced attenuation in integrated optical materials

    International Nuclear Information System (INIS)

    Evans, B.D.

    1989-01-01

    This paper reports that three materials commonly employed in opto-electronic integrated circuits evaluated for radiation-induced optical attenuation in the range 300 nm to 3000 nm. These include optically clear epoxy and crystalline lithium niobate after Co-60 exposure and crystalline tellurium dioxide after mixed gamma/fast-neutron exposure. In all these materials, however, induced loss was restricted to shorter wavelengths; attenuation induced at the telecommunications windows near 850, 1300 and 1550 nm was <0.1 dB/cm

  17. Continental Fog Attenuation Empirical Relationship from Measured Visibility Data

    Directory of Open Access Journals (Sweden)

    F. Nadeem

    2010-12-01

    Full Text Available Free Space Optics (FSO has the great potential for future communication applications. However, weather influenced reduced availability had been the main cause for its restricted growth. Among different weather influences fog plays the major role. A new model generalized for all FSO wavelengths, has been proposed for the prediction of continental fog attenuation using visibility data. The performance of the proposed model has been compared with well known models for measured attenuation data of Continental fog. The comparison has been performed in terms of Root Mean Square Error (RMSE.

  18. Evaluation of X ray attenuation by means of radiographic images

    International Nuclear Information System (INIS)

    Barros, Frieda Saicla; Paredes, Ramon S.C.; Godoi, Walmor C.; Souza, Gabriel Pinto de

    2011-01-01

    This paper's main goal is to adopt a qualitative methodology to evaluate the attenuation of x-radiation through X-ray images in polymeric materials plus residual lead. To determinate the images it was initially used an experimental setup at the Laboratory for Materials Diagnostics LACTEC. These results correspond to a more qualitative analysis, even with quantitative answers. Through analysis of radiographic images we can measure the intensity of radiation that goes through the plate, making possible to establish a relationship between the attenuation coefficient and the thickness of the material. (author)

  19. Attenuation of Gamma Rays by Concrete . Lead Slag Composites

    International Nuclear Information System (INIS)

    Ismail, I.M.; Sweelam, M.H.; Zaghloul, Y.R.; Aly, H.F.

    2008-01-01

    Using of wastes and industrial by-products as concrete aggregate to be used as structural and radiation shielded material has increased in the recent years. Concrete was mixed with different amounts of lead slag extracted from recycling of the spent automotive batteries as fine aggregates. The lead slag was used as partial replacement of sand in the studied composites. The concrete composites obtained were characterized in terms of density, water absorption, porosity, compressive strength and attenuation of γ- rays with different energies. The attenuation coefficient and the half value thickness of the different matrices were calculated and discussed

  20. Theoretical physics 8 statistical physics

    CERN Document Server

    Nolting, Wolfgang

    2018-01-01

    This textbook offers a clear and comprehensive introduction to statistical physics, one of the core components of advanced undergraduate physics courses. It follows on naturally from the previous volumes in this series, using methods of probability theory and statistics to solve physical problems. The first part of the book gives a detailed overview on classical statistical physics and introduces all mathematical tools needed. The second part of the book covers topics related to quantized states, gives a thorough introduction to quantum statistics, followed by a concise treatment of quantum gases. Ideally suited to undergraduate students with some grounding in quantum mechanics, the book is enhanced throughout with learning features such as boxed inserts and chapter summaries, with key mathematical derivations highlighted to aid understanding. The text is supported by numerous worked examples and end of chapter problem sets. About the Theoretical Physics series Translated from the renowned and highly successf...

  1. [Accuracy of attenuation coefficient obtained by 137Cs single-transmission scanning in PET: comparison with conventional germanium line source].

    Science.gov (United States)

    Matsumoto, Keiichi; Kitamura, Keishi; Mizuta, Tetsuro; Shimizu, Keiji; Murase, Kenya; Senda, Michio

    2006-02-20

    Transmission scanning can be successfully performed with a Cs-137 single-photon-emitting point source for three-dimensional PET imaging. This method was effective for postinjection transmission scanning because of differences in physical energy. However, scatter contamination in the transmission data lowers measured attenuation coefficients. The purpose of this study was to investigate the accuracy of the influence of object scattering by measuring the attenuation coefficients on the transmission images. We also compared the results with the conventional germanium line source method. Two different types of PET scanner, the SET-3000 G/X (Shimadzu Corp.) and ECAT EXACT HR(+) (Siemens/CTI) , were used. For the transmission scanning, the SET-3000 G/X and ECAT HR(+) were the Cs-137 point source and Ge-68/Ga-68 line source, respectively. With the SET-3000 G/X, we performed transmission measurement at two energy gate settings, the standard 600-800 keV as well as 500-800 keV. The energy gate setting of the ECAT HR(+) was 350-650 keV. The effects of scattering in a uniform phantom with different cross-sectional areas ranging from 201 cm(2) to 314 cm(2) to 628 cm(2) (apposition of the two 20 cm diameter phantoms) and 943 cm(2) (stacking of the three 20 cm diameter phantoms) were acquired without emission activity. First, we evaluated the attenuation coefficients of the two different types of transmission scanning using region of interest (ROI) analysis. In addition, we evaluated the attenuation coefficients with and without segmentation for Cs-137 transmission images using the same analysis. The segmentation method was a histogram-based soft-tissue segmentation process that can also be applied to reconstructed transmission images. In the Cs-137 experiment, the maximum underestimation was 3% without segmentation, which was reduced to less than 1% with segmentation at the center of the largest phantom. In the Ge-68/Ga-68 experiment, the difference in mean attenuation

  2. Accuracy of attenuation coefficient obtained by 137Cs single-transmission scanning in PET. Comparison with conventional germanium line source

    International Nuclear Information System (INIS)

    Matsumoto, Keiichi; Shimizu, Keiji; Senda, Michio; Kitamura, Keishi; Mizuta, Tetsuro; Murase, Kenya

    2006-01-01

    Transmission scanning can be successfully performed with a Cs-137 single-photon-emitting point source for three-dimensional PET imaging. This method was effective for postinjection transmission scanning because of differences in physical energy. However, scatter contamination in the transmission data lowers measured attenuation coefficients. The purpose of this study was to investigate the accuracy of the influence of object scattering by measuring the attenuation coefficients on the transmission images. We also compared the results with the conventional germanium line source method. Two different types of PET scanner, the SET-3000 G/X (Shimadzu Corp.) and ECAT EXACT HR + (Siemens/CTI), were used. For the transmission scanning, the SET-3000 G/X and ECAT HR + were the Cs-137 point source and Ge-68/Ga-68 line source, respectively. With the SET-3000 G/X, we performed transmission measurement at two energy gate settings, the standard 600-800 keV as well as 500-800 keV. The energy gate setting of the ECAT HR 2 + was 350-650 keV. The effects of scattering in a uniform phantom with different cross-sectional areas ranging from 201 cm 2 to 314 cm 2 to 628 cm 2 (apposition of the two 20 cm diameter phantoms) and 943 cm 2 (stacking of the three 20 cm diameter phantoms) were acquired without emission activity. First, we evaluated the attenuation coefficients of the two different types of transmission scanning using region of interest (ROI) analysis. In addition, we evaluated the attenuation coefficients with and without segmentation for Cs-137 transmission images using the same analysis. The segmentation method was a histogram-based soft-tissue segmentation process that can also be applied to reconstructed transmission images. In the Cs-137 experiment, the maximum underestimation was 3% without segmentation, which was reduced to less than 1% with segmentation at the center of the largest phantom. In the Ge-68/Ga-68 experiment, the difference in mean attenuation coefficients

  3. Supercollider physics

    International Nuclear Information System (INIS)

    Quigg, C.

    1985-03-01

    The physics that can be explored with multi-TeV supercolliders is reviewed, including parton distributions, hadron jet production, the standard electroweak theory and minimal extensions to it, technicolor, supersymmetry, and compositeness. 19 refs., 11 figs

  4. LHC physics

    National Research Council Canada - National Science Library

    Binoth, T

    2012-01-01

    ... collisions.Covering the topics in a pedagogical manner, the book introduces the theoretical and phenomenological framework of hadron collisions and presents the current theoretical models of frontier physics...

  5. [Physical urticaria].

    Science.gov (United States)

    Fleischer, M; Grabbe, J

    2004-04-01

    The different types of physical urticaria are triggered by mechanical and thermal stimuli, as well as electromagnetic waves. Localized forms restricted to the skin and mucous membranes are most common, but generalized urticaria with variable extracutaneous manifestations can also occur. Physical urticaria is usually sporadic but may rarely have a familial form; it is often associated with chronic urticaria. In most instances, the short time interval between the physical stimulus and reaction points to a causal relationship, but in delayed types the exact diagnosis may be missed without provocation tests. The clinical implication of physical urticaria is demonstrated by investigations showing a greater degree of disability in affected patients as compared to other types of urticaria. There is still an incomplete understanding of the crucial pathophysiological aspects; most likely inflammatory reactions involving leukocytes, endothelial cells and nerves stimulated by various mediators play an important role in this form of urticaria.

  6. Magic Physics?

    Science.gov (United States)

    Featonby, David

    2010-01-01

    This article examines several readily available "magic tricks" which base their "trickery" on physics principles, and questions the use of the word "magic" in the 21st century, both in popular children's science and in everyday language. (Contains 18 figures.)

  7. LHC physics

    National Research Council Canada - National Science Library

    Binoth, T

    2012-01-01

    "Exploring the phenomenology of the Large Hadron Collider (LHC) at CERN, LHC Physics focuses on the first years of data collected at the LHC as well as the experimental and theoretical tools involved...

  8. Engineering physics

    CERN Document Server

    Mukherji, Uma

    2015-01-01

    ENGINEERING PHYSICS is designed as a textbook for first year engineering students of a two semester course in Applied Physics according to new revised syllabus. However the scope of this book is not only limited to undergraduate engineering students and science students, it can also serve as a reference book for practicing scientists.Advanced technological topics like LCD, Squid, Maglev system, Electron microscopes, MRI, Photonics - Photonic fibre, Nano-particles, CNT, Quantum computing etc., are explained with basic underlying principles of Physics.This text explained following topics with numerous solved, unsolved problems and questions from different angles. Part-I contains crystal structure, Liquid crystal, Thermo-electric effect, Thermionic emission, Ultrasonic, Acoustics, semiconductor and magnetic materials. Whereas Part-2 contains Optics, X-rays, Electron optics, Dielectric materials, Quantum Physics and Schrodinger wave equation, Laser, Fibre-optics and Holography, Radio-activity, Super-conductivity,...

  9. Factory physics

    CERN Document Server

    Hopp, Wallace J.

    2011-01-01

    After a brief introductory chapter, "Factory Physics 3/e" is divided into three parts: I - The Lessons of History; II - Factory Physics; and III - Principles in Practice. The scientific approach to manufacturing and supply chain management, developed in Part II, is unique to this text. No other text or professional book provides a rigorous, principles-based foundation for manufacturing management. The Third Edition offers tighter connections between Lean Manufacturing, MRP/ERP, Six Sigma, Supply Chain Management, and Factory Physics. In addition to enhancing the historical overview of how these systems evolved, the authors show explicitly how users can achieve Lean Manufacturing objectives (faster response, less inventory) using the integration aspects of MRP/ERP/SCM systems along with the variance analysis methods of Six Sigma. Factory Physics provides the overarching framework that coordinates all of these initiatives into a single-focused strategy.

  10. Contest Physics.

    Science.gov (United States)

    Moehnke, Randy

    1994-01-01

    Discusses the use of contests to keep physics interesting and exciting for the students. Includes: balloon car, egg drop, tennis ball catapult, bridge building, mousetrap vehicle, musical instrument, slide photo, electric junk dissection, windmill generator, and solar heater. (MVL)

  11. Applied physics

    International Nuclear Information System (INIS)

    Anon.

    1980-01-01

    The Physics Division research program that is dedicated primarily to applied research goals involves the interaction of energetic particles with solids. This applied research is carried out in conjunction with the basic research studies from which it evolved

  12. Physical mathematics

    CERN Document Server

    Cahill, Kevin

    2013-01-01

    Unique in its clarity, examples and range, Physical Mathematics explains as simply as possible the mathematics that graduate students and professional physicists need in their courses and research. The author illustrates the mathematics with numerous physical examples drawn from contemporary research. In addition to basic subjects such as linear algebra, Fourier analysis, complex variables, differential equations and Bessel functions, this textbook covers topics such as the singular-value decomposition, Lie algebras, the tensors and forms of general relativity, the central limit theorem and Kolmogorov test of statistics, the Monte Carlo methods of experimental and theoretical physics, the renormalization group of condensed-matter physics and the functional derivatives and Feynman path integrals of quantum field theory.

  13. Physical oceanography

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, C.S.; Murty, V.S.N.

    The chapter on physical oceanography of the Indian Ocean is written keeping in mind the graduate students and researchers. It starts with a brief introduction (citing latest expeditions) followed by the coastal and near processes (wave climate...

  14. Astroparticle physics

    CERN Document Server

    Grupen, Claus

    2005-01-01

    The book describes the branch of astrophysics in which processes in the universe are investigated with experimental methods known from particle physics experiments. After a historical introduction to the basics of elementary particles, their interactions and the relevant detection techniques are described. The main body of the book concerns cosmic rays. The modern aspects of astroparticle physics are described in a chapter on cosmology. The book provides an orientation in the field of astroparticle physics that many beginners might look for. The physics issues are presented with little mathematics, and the results are illustrated by many diagrams. The reader has a chance to enter this field of astrophysics with a book that closes the gap between expert and popular level.

  15. On the attenuation of the ambient seismic field

    International Nuclear Information System (INIS)

    Weemstra, C.

    2013-01-01

    Although myriad applications exploiting the ambient seismic field have been reported to date, comparatively little attention has been paid to its potential to resolve subsurface attenuation. The ambient seismic field, however, may ultimately prove itself an invaluable asset in constraining subsurface attenuation structure. Especially areas with dense seismometer coverage hold great potential. Moreover, since this coverage continues to grow, significant developments may await in the future. Subsurface structure in terms of attenuation is of great importance for many reasons. For example, knowledge of the attenuation structure may aid in predicting ground motions caused by future large earthquakes. From a scientific perspective, a great deal of new information may be extracted, potentially fostering research in related fields (e.g., geodynamics, hydrology). Both from an environmental and economic point of view, inversion of the ambient seismic wavefield for attenuation structure may in the future provide a means to image hydrocarbon reservoirs. In sufficiently diffuse wavefields, simple cross-correlation of long noise time series recorded by two receivers results in the response at one of the receivers as if there was a source at the position of the other. I present a case study that shows that thus retrieved surface waves can be used to recover attenuation beneath an array of ocean-bottom seismometers. Given the small aperture of the seismic survey, this is unprecedented. Unambiguous interpretation of recovered attenuation values is of major importance. Lack of understanding of the effect that preprocessing has on the amplitude of the noise cross-correlation prevents such unambiguous interpretation. I carefully examine the effect spectral whitening has on the noise cross-correlation. Emphasis is given to the dependence of the amplitudes on the length of the time windows employed in the cross-correlation procedure. Short time-window lengths may require an additional

  16. Statistical physics

    CERN Document Server

    Sadovskii, Michael V

    2012-01-01

    This volume provides a compact presentation of modern statistical physics at an advanced level. Beginning with questions on the foundations of statistical mechanics all important aspects of statistical physics are included, such as applications to ideal gases, the theory of quantum liquids and superconductivity and the modern theory of critical phenomena. Beyond that attention is given to new approaches, such as quantum field theory methods and non-equilibrium problems.

  17. Nuclear physics

    International Nuclear Information System (INIS)

    Spicer, B.M.

    1981-01-01

    Major centres of experimental nuclear physics are at Melbourne University, A.N.U., the A.A.E.C., James Cook University and the University of Western Australia. Groups working in theoretical nuclear physics exist at Melbourne, A.N.U., the A.A.E.C., Flinders and Adelaide Universities and the University of Western Australia. The activities of these groups are summarised

  18. Football Physics

    Science.gov (United States)

    Gay, Timothy

    2006-05-01

    This talk discusses a series of one-minute physics lectures given to the ˜ 8 x 10^4 fans that attend the University of Nebraska home football games. The lecture topics range from gyroscopic motion to ionizing collisions between linebackers and I-backs. The problem of simultaneous edification and amusement of the fan in the stands is considered. Several physics tips for the Vols will be proffered.

  19. Nuclear physics

    International Nuclear Information System (INIS)

    Patel, S.B.

    1991-01-01

    This book is a simple and direct introduction to the tools of modern nuclear physics, both experimental and mathematical. Emphasizes physical intuition and illuminating analogies, rather than formal mathematics. Topics covered include particle accelerators, radioactive series, types of nuclear reactions, detection of the neutrino, nuclear isomerism, binding energy of nuclei, fission chain reactions, and predictions of the shell model. Each chapter contains problems and illustrative examples. Pre-requisites are calculus and elementary vector analysis

  20. Neutrino Physics

    CERN Multimedia

    CERN. Geneva; Dydak, Friedrich

    2001-01-01

    Starting from a review of theoretical concepts and experimental results in the early years of neutrino physics after Pauli's 1930 letter, today's double role of the neutrino as a cornerstone of the Standard Model and as a promising probe of physics beyond the Standard Model will be discussed. Topics comprise: - Conventional neutrino beams - Neutrinos as probes of the nucleon structure - Neutrinos from the universe - Dirac or Majorana neutrinos - Neutrino oscillations - MNS matrix - CP violation in the lepton sector - Neutrino factory.

  1. TOTEM Physics

    OpenAIRE

    Eggert, K; Anelli, G; Aurola, A; Avati, V; Berardi, V; Bottigli, U; Bozzo, M; Brucken, E; Buzzo, A; Calicchio, M; Capurro, F; Catanesi, M G; Ciocci, M A; Cuneo, S; Da Vià, C

    2006-01-01

    This article discusses the physics programme of the TOTEM experiment at the LHC. A new special beam optics with beta* = 90 m, enabling the measurements of the total cross-section, elastic pp scattering and diffractive phenomena already at early LHC runs, is explained. For this and the various other TOTEM running scenarios, the acceptances of the leading proton detectors and of the forward tracking stations for some physics processes are described.

  2. TOTEM physics

    Energy Technology Data Exchange (ETDEWEB)

    Anelli, G.; Aurola, A.; Avati, V.; Berardi, V.; Bottigli, U.; Bozzo, M.; Brucken, E.; Buzzo, A.; Calicchio, M.; Capurro, F.; Catanesi, M.G.; Ciocci, M.A.; Cuneo, S.; Da Vi' a, C.; Deile, M.; Dimovasili, E.; Eggert, K.; Eraluoto, M.; Ferro, F.; Giachero, A.; Hasi, J.; Haug, F.; Heino, J.; Hilden, T.; Jarron, P.; Kalliopuska, J.; Kaspar, J.; Kok, A.; Kundrat, V.; Kurvinen, K.; Lami, S.; Lamsa, J.; Latino, G.; Lauhakangas, R.; Lippmaa, E.; Lippmaa, J.; Lokajfeek, M.; LoVetere, M.; Macina, D.; Macri, M.; Meucci, M.; Minutoli, S.; Morelli, A.; Musico, P.; Negri, M.; Niewiadomski, H.; Noschis, E.; Ojala, J.; Oljemark, F.; Orava, R.; Oriunno, M.; Osterberg, K.; Paoletti, R.; Perrot, A.L.; Radermacher, E.; Radicioni, E.; Robutti, E.; Ropelewski, L.; Ruggiero, G.; Rummel, A.; Saarikko, H.; Sanguinetti, G.; Santroni, A.; Saramad, S.; Sauli, F.; Scribano, A.; Sette, G.; Smotlacha, J.; Snoeys, W.; Taylor, C.; Toppinen, A.; Trummal, A.; Turini, N.; Van Remortel, N.; Verardo, L.; Verdier, A.; Watts, S.; Whitmore, J

    2005-07-01

    This article discusses the physics programme of the TOTEM experiment at the LHC (Large Hadron Collider in CERN). A new special beam optics with {beta}{sup *} 90 m (betatron value), enabling the measurements of the total cross-section, elastic pp scattering and diffractive phenomena already at early LHC runs, is explained. For this and the various other TOTEM running scenarios, the acceptances of the leading proton detectors and of the forward tracking stations for some physics processes are described. (authors)

  3. Neutrino Physics

    CERN Multimedia

    CERN. Geneva. Audiovisual Unit

    2002-01-01

    Starting from a review of theoretical concepts and experimental results in the early years of neutrino physics after Pauli's 1930 letter, today's double role of the neutrino as a cornerstone of the Standard Model and as a promising probe of physics beyond the Standard Model will be discussed. Topics comprise: - Conventional neutrino beams - Neutrinos as probes of the nucleon structure - Neutrinos from the universe - Dirac or Majorana neutrinos - Neutrino oscillations - MNS matrix - CP violation in the lepton sector - Neutrino factory.

  4. Quantum Physics

    Science.gov (United States)

    Le Bellac, Michel

    2006-03-01

    Quantum physics allows us to understand the nature of the physical phenomena which govern the behavior of solids, semi-conductors, lasers, atoms, nuclei, subnuclear particles and light. In Quantum Physics, Le Bellac provides a thoroughly modern approach to this fundamental theory. Throughout the book, Le Bellac teaches the fundamentals of quantum physics using an original approach which relies primarily on an algebraic treatment and on the systematic use of symmetry principles. In addition to the standard topics such as one-dimensional potentials, angular momentum and scattering theory, the reader is introduced to more recent developments at an early stage. These include a detailed account of entangled states and their applications, the optical Bloch equations, the theory of laser cooling and of magneto-optical traps, vacuum Rabi oscillations, and an introduction to open quantum systems. This is a textbook for a modern course on quantum physics, written for advanced undergraduate and graduate students. Completely original and contemporary approach, using algebra and symmetry principles Introduces recent developments at an early stage, including many topics that cannot be found in standard textbooks. Contains 130 physically relevant exercises

  5. Spatially resolved ultrasonic attenuation in resistance spot welds: implications for nondestructive testing.

    Science.gov (United States)

    Mozurkewich, George; Ghaffari, Bita; Potter, Timothy J

    2008-09-01

    Spatial variation of ultrasonic attenuation and velocity has been measured in plane parallel specimens extracted from resistance spot welds. In a strong weld, attenuation is larger in the nugget than in the parent material, and the region of increased attenuation is surrounded by a ring of decreased attenuation. In the center of a stick weld, attenuation is even larger than in a strong weld, and the low-attenuation ring is absent. These spatial variations are interpreted in terms of differences in grain size and martensite formation. Measured frequency dependences indicate the presence of an additional attenuation mechanism besides grain scattering. The observed attenuations do not vary as commonly presumed with weld quality, suggesting that the common practice of using ultrasonic attenuation to indicate weld quality is not a reliable methodology.

  6. Self-attenuation of gamma rays during radioactivity concentration analysis of environmental samples

    International Nuclear Information System (INIS)

    Watson, D.; Dharmasiri, J.; Akber, R.

    2001-01-01

    Gamma spectroscopy using HPGe detector systems is a readily used technique for routine analysis of radioactivity in environmental samples. The systems are generally calibrated using standards of known radioactivity and composition. Radioactivity in environmental samples is generally distributed in the bulk of the material. When a sample of finite thickness is analysed through gamma spectroscopy, a proportion of the gamma rays emitted from the sample is either stopped or scattered from the sample material itself. These processes of self-absorption and self-attenuation depend upon the physical and elemental composition of the sample and the energy of the gamma radiation. Since environmental samples vary in composition, instrument calibration using a fixed matrix composition may not be valid for a diversity of samples. We selected and analysed five sample matrices to investigate the influence of self-absorption and self-attenuation in environmental samples. Our selection consisted of bentonite and kaolin representing clay, quartz representing silica, ash representing prepared biota, and analytical grade MnO 2 representing a co-precipitant used for extractive radioactivity from aqueous samples. Our findings show that within 5% of uncertainty the silica based standards can be used to cover the environmental samples of varying clay (silica content). The detection efficiency for ash and MnO 2 could be different particularly in the 30 - 100 keV energy range. The differences in sample behaviour can be explained on the basis of atomic number, mass number and density

  7. Attenuation of hydrogen sulfide at construction and demolition debris landfills using alternative cover materials.

    Science.gov (United States)

    Xu, Qiyong; Townsend, Timothy; Reinhart, Debra

    2010-04-01

    The attenuation of H(2)S emissions by various landfill cover materials was evaluated using both laboratory and field experiments. The results demonstrated that cover materials consisting of selected waste products (compost and yard trash) and soils amended with quicklime and calcium carbonate effectively attenuated H(2)S emissions and detectable H(2)S emissions were only encountered in a testing plot using a sandy soil cover (average emission rate was 4.67x10(-6)mgm(-2)s(-1)). H(2)S concentration profiles in the cover materials indicated that H(2)S was removed as it migrated through the cover materials. At the same depth in the testing area, the H(2)S concentration in the sandy soil field plot was always higher than that of other testing plots because the sand (a) demonstrated less ability to remove H(2)S and (b) exhibited a higher H(2)S concentration at the base of the cover. Laboratory experiments confirmed these observations, with a combination of physical adsorption, chemical reactions, and biological oxidation, accounting for the enhanced removal. In addition to removal, the results suggest that some of the cover materials reduced H(2)S generation by creating less favorable conditions for sulfate-reducing bacteria (e.g., high pH and temperature). Copyright 2009 Elsevier Ltd. All rights reserved.

  8. Evaluation of the attenuating properties of selected Greek clays for toxic inorganic elements in landfill sites.

    Science.gov (United States)

    Mimides, T; Perraki, T

    2000-05-15

    Heavy metal attenuation properties of selected clay material collected from miscellaneous Greek sites is investigated and tested in the laboratory for their suitability, either as liners in hydrologically unsafe sites or as earth covers for sanitary landfill sites. Eleven potentially hazardous elements (As, Be, Cd, Cr, Cu, Hg, Ni, Pb, Se, V, and Zn) generated by a co-disposal landfill leachate have been considered. Experimental column and static equilibrium methods for the determination of dispersion and adsorption are described. Molecular diffusion dominates the migration phenomena with a velocity range between 1.3 x 10(-5) and 3.5 x 10(-4) cm/s throughout the experiments. A simple way to evaluate dispersion coefficients from breakthrough curves gave values of between 3.90 x 10(-6) and 3.5 x 10(-4) cm2/s, with a mean value of 1.5 x 10(-5). Static adsorption equilibrium studies supported by column runs showed that Freundlich (F = kCn) isotherms express in a better way the assimilative capacities of the tested clays, with k and n values ranging from 0.06 to 1.99 and 0.55 to 1.48 correspondingly. Mathematical models involving non-linear parabolic equations are involved. The experimental data, together with finite difference techniques and some physical clay characteristics, produced trilinear textural diagrams and predictive flow transport convection-dispersion breakthrough curves for a quick estimation of the attenuating properties of clays for heavy metals.

  9. High-resolution gamma ray attenuation density measurements on mining exploration drill cores, including cut cores

    Science.gov (United States)

    Ross, P.-S.; Bourke, A.

    2017-01-01

    Physical property measurements are increasingly important in mining exploration. For density determinations on rocks, one method applicable on exploration drill cores relies on gamma ray attenuation. This non-destructive method is ideal because each measurement takes only 10 s, making it suitable for high-resolution logging. However calibration has been problematic. In this paper we present new empirical, site-specific correction equations for whole NQ and BQ cores. The corrections force back the gamma densities to the "true" values established by the immersion method. For the NQ core caliber, the density range extends to high values (massive pyrite, 5 g/cm3) and the correction is thought to be very robust. We also present additional empirical correction factors for cut cores which take into account the missing material. These "cut core correction factors", which are not site-specific, were established by making gamma density measurements on truncated aluminum cylinders of various residual thicknesses. Finally we show two examples of application for the Abitibi Greenstone Belt in Canada. The gamma ray attenuation measurement system is part of a multi-sensor core logger which also determines magnetic susceptibility, geochemistry and mineralogy on rock cores, and performs line-scan imaging.

  10. Pioglitazone attenuates the opioid withdrawal and vulnerability to relapse to heroin seeking in rodents.

    Science.gov (United States)

    de Guglielmo, Giordano; Kallupi, Marsida; Scuppa, Giulia; Demopulos, Gregory; Gaitanaris, George; Ciccocioppo, Roberto

    2017-01-01

    Relapse to opioids is often driven by the avoidance of the aversive states of opioid withdrawal. We recently demonstrated that activation of peroxisome proliferator-activated receptor gamma (PPARγ) by pioglitazone reduces the motivation for heroin and attenuates its rewarding properties. However, the role of PPARγ in withdrawal and other forms of relapse to heroin is unknown. To further address this issue, we investigated the role of PPARγ on the development and expression of morphine withdrawal in mice and the effect of pioglitazone on several forms of heroin relapse in rats. We induced physical dependence to morphine in mice by injecting morphine twice daily for 6 days. Withdrawal syndrome was precipitated on day 6 with an injection of naloxone. In addition, different groups of rats were trained to self-administer heroin and, after the extinction, the relapse was elicited by cues, priming, or stress. The effect of different doses of pioglitazone was tested on these different paradigms. Data show that chronic and acute administration of pioglitazone attenuates morphine withdrawal symptoms, and these effects are mediated by activation of PPARγ receptors. Activation of PPARγ by pioglitazone also abolishes yohimbine-induced reinstatement of heroin seeking and reduces heroin-induced reinstatement, while it does not affect cue-induced relapse. These findings provide new insights on the role of PPARγ on opioid dependence and suggest that pioglitazone may be useful for the treatment of opioid withdrawal in opioid-addicted individuals.

  11. Interval training attenuates the metabolic disturbances in type 1 diabetes rat model.

    Science.gov (United States)

    Rocha, Ricelli Endrigo Ruppel; Coelho, Isabela; Pequito, Daniela Cristina T; Yamagushi, Adriana; Borghetti, Gina; Yamazaki, Ricardo Key; Brito, Gleisson Alisson Pereira de; Machado, Juliano; Kryczyk, Marcelo; Nunes, Everson Araújo; Venera, Graciela; Fernandes, Luiz Claudio

    2013-11-01

    This study investigated the effect of interval training on blood biochemistry and immune parameters in type 1 diabetic rats. Male Wistar rats were divided into four groups: sedentary (SE, n = 15), interval training (IT, n = 17), diabetic sedentary (DSE, n = 17), diabetic interval training (DIT, n = 17). Diabetes was induced by i.v. injection of streptozotocin (60 mg/kg). Swimming Interval Training consisted of 30-s exercise with 30-s rest, for 30 minutes, during 6 weeks, four times a week, with an overload of 15% of body mass. Plasma glucose, lactate, triacylglycerol and total cholesterol concentrations, phagocytic capacity, cationic vesicle content, and superoxide anion and hydrogen peroxide production by blood neutrophils and peritoneal macrophages were evaluated. Proliferation of mesenteric lymphocytes was also estimated. Interval training resulted in attenuation of the resting hyperglycemic state and decreased blood lipids in the DIT group. Diabetes increased the functionality of blood neutrophils and peritoneal macrophages in the DSE group. Interval training increased all functionality parameters of peritoneal macrophages in the IT group. Interval training also led to a twofold increase in the proliferation of mesenteric lymphocytes after 6 weeks of exercise in the DIT group. Low-volume high-intensity physical exercise attenuates hyperglycemia and dislipidemia induced by type 1 diabetes, and induces changes in the functionality of innate and acquired immunity.

  12. Cardiovascular Reactivity, Stress, and Physical Activity

    Directory of Open Access Journals (Sweden)

    Chun-Jung eHuang

    2013-11-01

    Full Text Available Psychological stress has been proposed as a major contributor to the progression of cardiovascular disease (CVD. Acute mental stress can activate the sympathetic-adrenal-medullary (SAM axis, eliciting the release of catecholamines (NE and EPI resulting in the elevation of heart rate (HR and blood pressure (BP. Combined stress (psychological and physical can exacerbate these cardiovascular responses, which may partially contribute to the elevated risk of CVD and increased proportionate mortality risks experienced by some occupations (e.g., firefighting and law enforcement. Studies have supported the benefits of physical activity on physiological and psychological health, including the cardiovascular response to acute stress. Aerobically trained individuals exhibit lower sympathetic nervous system (e.g., HR reactivity and enhanced cardiovascular efficiency (e.g., lower vascular reactivity and decreased recovery time in response to physical and/or psychological stress. In addition, resistance training has been demonstrated to attenuate cardiovascular responses and improve mental health. This review will examine stress-induced cardiovascular reactivity and plausible explanations for how exercise training and physical fitness (aerobic and resistance exercise can attenuate cardiovascular responses to stress. This enhanced functionality may facilitate a reduction in the incidence of stroke and myocardial infarction. Finally, this review will also address the interaction of obesity and physical activity on cardiovascular reactivity and CVD.

  13. Dehydroepiandrosterone Attenuates Cocaine-Seeking Behaviour Independently of Corticosterone Fluctuations.

    Science.gov (United States)

    Maayan, R; Hirsh, L; Yadid, G; Weizman, A

    2015-11-01

    The neurosteroid dehydroepiandrosterone (DHEA) is involved in the pathophysiology of several psychiatric disorders, including cocaine addiction. We have previously shown that DHEA attenuates cocaine-seeking behaviour, and also that DHEA decreases corticosterone (CORT) levels in plasma and the prefrontal cortex. Previous studies have found that rats demonstrate cocaine-seeking behaviour only when the level of CORT reaches a minimum threshold. In the present study, we investigated whether the attenuating effect of DHEA on cocaine seeking is a result of it reducing CORT levels rather than a result of any unique neurosteroid properties. Rats received either daily DHEA injections (2 mg/kg, i.p.) alone, daily DHEA (2 mg/kg, i.p.) with CORT infusion (to maintain stable basal levels of CORT; 15 mg/kg, s.c.) or vehicle (i.p.) as control, throughout self-administration training and extinction sessions. We found that both DHEA-treated and DHEA + CORT-treated groups showed a significantly lower number of active lever presses compared to controls throughout training and extinction sessions, as well as at cocaine-primed reinstatement. DHEA-treated rats showed lower CORT levels throughout the experimental phases compared to DHEA + CORT-treated and control rats. Additionally, we show that DHEA administered to cocaine-trained rats throughout extinction sessions, or immediately before reinstatement, attenuated cocaine seeking. These findings indicate that DHEA attenuates cocaine-seeking behaviour independently of fluctuations in CORT levels. © 2015 British Society for Neuroendocrinology.

  14. Photosynthetic efficiency of Chlamydomonas reinhardtii in attenuated, flashing light

    NARCIS (Netherlands)

    Vejrazka, C.; Janssen, M.G.J.; Streefland, M.; Wijffels, R.H.

    2012-01-01

    As a result of mixing and light attenuation, algae in a photobioreactor (PBR) alternate between light and dark zones and, therefore, experience variations in photon flux density (PFD). These variations in PFD are called light/dark (L/D) cycles. The objective of this study was to determine how these

  15. Ixeris dentata (Thunb) Nakai attenuates cognitive impairment in ...

    African Journals Online (AJOL)

    Ixeris dentata (Thunb) Nakai attenuates cognitive impairment in MPTP-treated mouse model of Parkinson's disease. ... Conclusion: IDE exhibits good protection against MPTP-induced behavioral deficits via potential antioxidant defense mechanisms. Therefore, IDE could potentially be developed as a therapeutic approach ...

  16. Amplification and Attenuation across USArray using Ambient Noise Wavefront Tracking

    KAUST Repository

    Bowden, Daniel C.

    2017-11-15

    As seismic travel-time tomography continues to be refined using data from the vast USArray dataset, it is advantageous to also exploit the amplitude information carried by seismic waves. We use ambient noise cross correlation to make observations of surface-wave amplification and attenuation at shorter periods (8 – 32 seconds) than can be observed with only traditional teleseismic earthquake sources. We show that the wavefront tracking approach of [Lin et al., 2012a] can be successfully applied to ambient noise correlations, yielding results quite similar to those from earthquake observations at periods of overlap. This consistency indicates that the wavefront tracking approach is viable for use with ambient noise correlations, despite concerns of the inhomogeneous and unknown distribution of noise sources. The resulting amplification and attenuation maps correlate well with known tectonic and crustal structure; at the shortest periods, our amplification and attenuation maps correlate well with surface geology and known sedimentary basins, while our longest period amplitudes are controlled by crustal thickness and begin to probe upper mantle materials. These amplification and attenuation observations are sensitive to crustal materials in different ways than travel-time observations and may be used to better constrain temperature or density variations. We also value them as an independent means of describing the lateral variability of observed Rayleigh-wave amplitudes without the need for 3D tomographic inversions.

  17. Oral vaccination with attenuated Salmonella choleraesuis C500 ...

    African Journals Online (AJOL)

    user

    Marshall, 1983), and well known as the major gastro- duodenal ... The CagA is encoded in a pathogenicity island known as 'Cag PAI' and is .... HindIII to release the CagA fragment. The purified .... vaccine strain attenuated by chemical methods, which is .... pylori antigens is achieved using a non-toxic mutant of E. coli heat-.

  18. NATURAL ATTENUATION OF COPPER IN SOILS AND SOIL MINERALS - II

    Science.gov (United States)

    The bioabailability and toxicity of Cu in soils is controlled by a number of soil properties and processes. Some of these such as pH, adsorption/desorption and competition with beneficial cations have been extensively studied. However, the effects of natural attenuation (or aging...

  19. Context discovery using attenuated Bloom codes: model description and validation

    NARCIS (Netherlands)

    Liu, F.; Heijenk, Geert

    A novel approach to performing context discovery in ad-hoc networks based on the use of attenuated Bloom filters is proposed in this report. In order to investigate the performance of this approach, a model has been developed. This document describes the model and its validation. The model has been

  20. Chemical Oxygen Demand (COD) Attenuation of Methyl Red in ...

    African Journals Online (AJOL)

    ADOWIE PERE

    Department of Pure & Industrial Chemistry, Faculty of Science , University of ... ABSTRACT: Attenuation of methyl red dyestuff in water was assessed by ... alternative low cost materials (Ahmad et al., 2010, .... ml distilled water as blank was also taken through the .... quality control measures such as washing of glassware,.

  1. Comparison of Attenuation of petroleum hydrocarbons in surface ...

    African Journals Online (AJOL)

    These concentrations further changed at day 56 with the non amended soils now having the lowest TPH concentrations. 56 days after spiking with TPH, only the C 10 – C 12 and > C16 carbon number fractions were detected at both depths. Results suggest that natural attenuation can be a viable remediation strategy in ...

  2. Ketoconazole attenuates radiation-induction of tumor necrosis factor

    Energy Technology Data Exchange (ETDEWEB)

    Hallahan, D.E.; Virudachalam, S.; Kufe, D.W.; Weichselbaum, R.R. [Dana Farber Cancer Institute, Boston, MA (United States)

    1994-07-01

    Previous work has demonstrated that inhibitors of phospholipase A2 attenuate ionizing radiation-induced arachidonic acid production, protein kinase C activation, and prevent subsequent induction of the tumor necrosis factor gene. Because arachidonic acid contributes to radiation-induced tumor necrosis factor expression, the authors analyzed the effects of agents which alter arachidonate metabolism on the regulation of this gene. Phospholipase A2 inhibitors quinicrine, bromphenyl bromide, and pentoxyfylline or the inhibitor of lipoxygenase (ketoconazole) or the inhibitor of cycloxygenase (indomethacine) were added to cell culture 1 h prior to irradiation. Radiation-induced tumor necrosis factor gene expression was attenuated by each of the phospholipase A2 inhibitors (quinicrine, bromphenylbromide, and pentoxyfylline). Furthermore, ketoconazole attenuated X ray induced tumor necrosis factor gene expression. Conversely, indomethacin enhanced tumor necrosis factor expression following irradiation. The finding that radiation-induced tumor necrosis factor gene expression was attenuated by ketoconazole suggests that the lipoxygenase pathway participates in signal transduction preceding tumor necrosis factor induction. Enhancement of tumor necrosis factor expression by indomethacin following irradiation suggests that prostaglandins produced by cyclooxygenase act as negative regulators of tumor necrosis factor expression. Inhibitors of tumor necrosis factor induction ameliorate acute and subacute sequelae of radiotherapy. The authors propose therefore, that ketoconazole may reduce acute radiation sequelae such as mucositis and esophagitis through a reduction in tumor necrosis factor induction or inhibition of phospholipase A2 in addition to its antifungal activity. 25 refs., 2 figs.

  3. Characteristics of liver tissue for attenuate the gamma radiation

    International Nuclear Information System (INIS)

    Arcos P, A.; Rodriguez N, S.; Pinedo S, A.; Amador V, P.; Chacon R, A.; Vega C, H.R.

    2005-01-01

    It was determined the lineal attenuation coefficient of hepatic tissue before gamma radiation of a source of 137 Cs. When exposing organic material before X or gamma radiation fields, part of the energy of the photons is absorbed by the material, while another part crosses it without producing any effect. The quantity of energy that is absorbed is a measure of the dose that receives the material. The three main mechanisms by means of which the gamma rays interacting with the matter are: The Photoelectric Effect, the Compton dispersion and the Even production; the sum of these three processes is translated in the attenuation coefficient of the radiation. In this work we have used hepatic tissue of bovine, as substitute of the human hepatic tissue, and we have measured the lineal attenuation coefficient for photons of 0.662 MeV. Through a series of calculations we have determined the lineal attenuation coefficient for photons from 10 -3 to 10 -5 MeV and the measured coefficient was compared with the one calculated. (Author)

  4. Chemical oxygen demand (cod) attenuation of methyl red in water ...

    African Journals Online (AJOL)

    Chemical oxygen demand (cod) attenuation of methyl red in water using biocarbons obtained from Nipa palm leaves. ... eco-friendly and locally accessible biocarbon for mitigation of organic contaminants in water. Keywords: Chemical oxygen demand, biocarbon, methyl red, biodegradation, bioremediation, Nipa palm ...

  5. Variable optical attenuator fabricated by direct UV writing

    DEFF Research Database (Denmark)

    Svalgaard, Mikael; Færch, Kjartan Ullitz; Andersen, L.U.

    2003-01-01

    It is demonstrated that direct ultraviolet writing of waveguides is a method suitable for mass production of compact variable optical attenuators with low insertion loss, low polarization-dependent loss, and high dynamic range. The fabrication setup is shown to be robust, providing good device...

  6. Wave attenuation model for dephasing and measurement of ...

    Indian Academy of Sciences (India)

    An analysis of previous models to simulate inelastic scattering in such systems is presented and a relatively new model based on wave attenuation is introduced. The problem of Aharonov–Bohm (AB) oscillations in conductance of a mesoscopic ring is studied. We show that the conductance is symmetric under flux reversal ...

  7. Timing attention : Cuing target onset interval attenuates the attentional blink

    NARCIS (Netherlands)

    Martens, S; Johnson, A

    Three experiments tested whether the attentional blink (AB; a deficit in reporting the second of two targets when it occurs 200-500 msec after the first) can be attenuated by providing information about the target onset asynchrony (TOA) of the second target relative to the first. Blocking the TOA

  8. Measurement of atomic number and mass attenuation coefficient in ...

    Indian Academy of Sciences (India)

    literature on the measurement of mass attenuation coefficient in magnesium ferrite. The knowledge of photon ... pure) MgO and Fe2O3. The details of experimental ... and (4 4 0) planes belonging to cubic spinel structure. The XRD pattern ...

  9. Interpersonal sensitivity and persistent attenuated psychotic symptoms in adolescence.

    Science.gov (United States)

    Masillo, Alice; Brandizzi, M; Valmaggia, L R; Saba, R; Lo Cascio, N; Lindau, J F; Telesforo, L; Venturini, P; Montanaro, D; Di Pietro, D; D'Alema, M; Girardi, P; Fiori Nastro, P

    2018-03-01

    Interpersonal sensitivity defines feelings of inner-fragility in the presence of others due to the expectation of criticism or rejection. Interpersonal sensitivity was found to be related to attenuated positive psychotic symptom during the prodromal phase of psychosis. The aims of this study were to examine if high level of interpersonal sensitivity at baseline are associated with the persistence of attenuated positive psychotic symptoms and general psychopathology at 18-month follow-up. A sample of 85 help-seeking individuals (mean age = 16.6, SD = 5.05) referred an Italian early detection project, completed the interpersonal sensitivity measure and the structured interview for prodromal symptoms (SIPS) at baseline and were assessed at 18-month follow-up using the SIPS. Results showed that individuals with high level of interpersonal sensitivity at baseline reported high level of attenuated positive psychotic symptoms (i.e., unusual thought content) and general symptoms (i.e., depression, irritability and low tolerance to daily stress) at follow-up. This study suggests that being "hypersensitive" to interpersonal interactions is a psychological feature associated with attenuated positive psychotic symptoms and general symptoms, such as depression and irritability, at 18-month follow-up. Assessing and treating inner-self fragilities may be an important step of early detection program to avoid the persistence of subtle but very distressing long-terms symptoms.

  10. Attenuation of polychlorinated biphenyl sorption to charcoal by humic acids

    NARCIS (Netherlands)

    Koelmans, A.A.; Meulman, B.; Meijer, T.; Jonker, M.T.O.

    2009-01-01

    Strong sorption to black carbon may limit the environmental risks of organic pollutants, but interactions with cosorbing humic acid (HA) may interfere. We studied the attenuative effect of HA additions on the sorption of polychlorinated biphenyls (PCBs) to a charcoal. "Intrinsic" sorption to

  11. Seismic noise attenuation using an online subspace tracking algorithm

    NARCIS (Netherlands)

    Zhou, Yatong; Li, Shuhua; Zhang, D.; Chen, Yangkang

    2018-01-01

    We propose a new low-rank based noise attenuation method using an efficient algorithm for tracking subspaces from highly corrupted seismic observations. The subspace tracking algorithm requires only basic linear algebraic manipulations. The algorithm is derived by analysing incremental gradient

  12. Gamma ray attenuation coefficient measurement for neutron-absorbent materials

    Energy Technology Data Exchange (ETDEWEB)

    Jalali, Majid [Isfahan Nuclear Science and Technology Research Institute (NSTRT), Reactor and Accelerators Research and Development School, Atomic Energy Organization (Iran, Islamic Republic of)], E-mail: m_jalali@entc.org.ir; Mohammadi, Ali [Faculty of Science, Department of Physics, University of Kashan, Km. 6, Ravand Road, Kashan (Iran, Islamic Republic of)

    2008-05-15

    The compounds Na{sub 2}B{sub 4}O{sub 7}, H{sub 3}BO{sub 3}, CdCl{sub 2} and NaCl and their solutions attenuate gamma rays in addition to neutron absorption. These compounds are widely used in the shielding of neutron sources, reactor control and neutron converters. Mass attenuation coefficients of gamma related to the four compounds aforementioned, in energies 662, 778.9, 867.38, 964.1, 1085.9, 1173, 1212.9, 1299.1,1332 and 1408 keV, have been determined by the {gamma} rays transmission method in a good geometry setup; also, these coefficients were calculated by MCNP code. A comparison between experiments, simulations and Xcom code has shown that the study has potential application for determining the attenuation coefficient of various compound materials. Experiment and computation show that H{sub 3}BO{sub 3} with the lowest average Z has the highest gamma ray attenuation coefficient among the aforementioned compounds.

  13. Attenuation studies near K-absorption edges using Compton ...

    Indian Academy of Sciences (India)

    The results are consistent with theoretical values derived from the XCOM package. Keywords. Photon interaction; 241Am; gamma ray attenuation; Compton scattering; absorption edge; rare earth elements. PACS Nos 32.80.-t; 32.90.+a. 1. Introduction. Photon interaction studies at energies around the absorption edge have ...

  14. Simulation on the shock attenuation behavior of coupled RHA and ...

    African Journals Online (AJOL)

    This paper presents the shock attenuation behavior of engineering materials namely Rolled Homogenous Armor (RHA) and sandwich composite when subject to blast loadings. Blast loading on sandwich composite structure and monolithic material are investigated using LSDYNA 3D with Arbitrary LagrangianEulerian ...

  15. On self-attenuation corrections in gamma-ray spectrometry

    International Nuclear Information System (INIS)

    Bolivar, J.P.; Garcia-Leon, M.; Garcia-Tenorio, R.

    1997-01-01

    In this paper we discuss and justify the dependence on the sample density and gamma energy of the self-attenuation correction factor, f, in the transmission method for the full energy peak efficiency calibration of Ge detectors. It is suggested as a method for the direct computing of f in the case that the sample composition is known. (Author)

  16. Outdoor FSO Communications Under Fog: Attenuation Modeling and Performance Evaluation

    KAUST Repository

    Esmail, Maged Abdullah

    2016-07-18

    Fog is considered to be a primary challenge for free space optics (FSO) systems. It may cause attenuation that is up to hundreds of decibels per kilometer. Hence, accurate modeling of fog attenuation will help telecommunication operators to engineer and appropriately manage their networks. In this paper, we examine fog measurement data coming from several locations in Europe and the United States and derive a unified channel attenuation model. Compared with existing attenuation models, our proposed model achieves a minimum of 9 dB, which is lower than the average root-mean-square error (RMSE). Moreover, we have investigated the statistical behavior of the channel and developed a probabilistic model under stochastic fog conditions. Furthermore, we studied the performance of the FSO system addressing various performance metrics, including signal-to-noise ratio (SNR), bit-error rate (BER), and channel capacity. Our results show that in communication environments with frequent fog, FSO is typically a short-range data transmission technology. Therefore, FSO will have its preferred market segment in future wireless fifth-generation/sixth-generation (5G/6G) networks having cell sizes that are lower than a 1-km diameter. Moreover, the results of our modeling and analysis can be applied in determining the switching/thresholding conditions in highly reliable hybrid FSO/radio-frequency (RF) networks.

  17. PET attenuation coefficients from CT images: experimental evaluation of the transformation of CT into PET 511-keV attenuation coefficients.

    Science.gov (United States)

    Burger, C; Goerres, G; Schoenes, S; Buck, A; Lonn, A H R; Von Schulthess, G K

    2002-07-01

    The CT data acquired in combined PET/CT studies provide a fast and essentially noiseless source for the correction of photon attenuation in PET emission data. To this end, the CT values relating to attenuation of photons in the range of 40-140 keV must be transformed into linear attenuation coefficients at the PET energy of 511 keV. As attenuation depends on photon energy and the absorbing material, an accurate theoretical relation cannot be devised. The transformation implemented in the Discovery LS PET/CT scanner (GE Medical Systems, Milwaukee, Wis.) uses a bilinear function based on the attenuation of water and cortical bone at the CT and PET energies. The purpose of this study was to compare this transformation with experimental CT values and corresponding PET attenuation coefficients. In 14 patients, quantitative PET attenuation maps were calculated from germanium-68 transmission scans, and resolution-matched CT images were generated. A total of 114 volumes of interest were defined and the average PET attenuation coefficients and CT values measured. From the CT values the predicted PET attenuation coefficients were calculated using the bilinear transformation. When the transformation was based on the narrow-beam attenuation coefficient of water at 511 keV (0.096 cm(-1)), the predicted attenuation coefficients were higher in soft tissue than the measured values. This bias was reduced by replacing 0.096 cm(-1) in the transformation by the linear attenuation coefficient of 0.093 cm(-1) obtained from germanium-68 transmission scans. An analysis of the corrected emission activities shows that the resulting transformation is essentially equivalent to the transmission-based attenuation correction for human tissue. For non-human material, however, it may assign inaccurate attenuation coefficients which will also affect the correction in neighbouring tissue.

  18. Seismic wave attenuation and velocity dispersion in UAE carbonates

    Science.gov (United States)

    Ogunsami, Abdulwaheed Remi

    Interpreting the seismic property of fluids in hydrocarbon reservoirs at low frequency scale has been a cherished goal of petroleum geophysics research for decades. Lately, there has been tremendous interest in understanding attenuation as a result of fluid flow in porous media. Although interesting, the emerging experimental and theoretical information still remain ambiguous and are practically not utilized for reasons not too obscure. Attenuation is frequency dependent and hard to measure in the laboratory at low frequency. This thesis describes and reports the results of an experimental study of low frequency attenuation and velocity dispersion on a selected carbonate reservoir samples in the United Arab Emirates (UAE). For the low frequency measurements, stress-strain method was used to measure the moduli from which the velocity is derived. Attenuation was measured as the phase difference between the applied stress and the strain. For the ultrasonic component, the pulse propagation method was employed. To study the fluid effect especially at reservoir in situ conditions, the measurements were made dry and saturated with liquid butane and brine at differential pressures of up to 5000 psi with pore pressure held constant at 500 psi. Similarly to what has been documented in the literatures for sandstone, attenuation of the bulk compressibility mode dominates the losses in these dry and somewhat partially saturated carbonate samples with butane and brine. Overall, the observed attenuation cannot be simply said to be frequency dependent within this low seismic band. While attenuation seems to be practically constant in the low frequency band for sample 3H, such conclusion cannot be made for sample 7H. For the velocities, significant dispersion is observed and Gassmann generally fails to match the measured velocities. Only the squirt model fairly fits the velocities, but not at all pressures. Although the observed dispersion is larger than Biot's prediction, the fact

  19. Plasma physics

    CERN Document Server

    Cairns, R A

    1985-01-01

    This book is intended as an introduction to plasma physics at a level suitable for advanced undergraduates or beginning postgraduate students in physics, applied mathematics or astrophysics. The main prerequisite is a knowledge of electromagnetism and of the associated mathematics of vector calculus. SI units are used throughout. There is still a tendency amongst some plasma physics researchers to· cling to C.g.S. units, but it is the author's view that universal adoption of SI units, which have been the internationally agreed standard since 1960, is to be encouraged. After a short introductory chapter, the basic properties of a plasma con­ cerning particle orbits, fluid theory, Coulomb collisions and waves are set out in Chapters 2-5, with illustrations drawn from problems in nuclear fusion research and space physics. The emphasis is on the essential physics involved and (he theoretical and mathematical approach has been kept as simple and intuitive as possible. An attempt has been made to draw attention t...

  20. Learning Physics

    International Nuclear Information System (INIS)

    Cohen, E.

    2005-01-01

    Full Text:The issue of Teaching physics vs Learning physics in our institutions of higher learning will be discussed. Physics is taught mainly by frontal lectures an old (and proven) method. The great advancements of the Information Age are introduced by exposing the students to vast amounts of computerized information and directing them to numerical problem solving by interacting with the computer. These modern methods have several drawbacks: 1. Students get the impression of easy material acquisition while in fact it becomes superficial. 2. There is little integration of topics that are taught in different courses. 3. Insufficient interest is built among undergraduate students to pursue studies that involve deeper thinking and independent research (namely, studies towards a doctoral degree). Learning physics is a formative process in the education of physicists, natural scientists and engineers. It must be based on discussions and exchange of ideas among the students, since understanding the studied material means being able to explain it to a colleague. Some universities in the US initiated programs of learning physics by creating an environment in which small groups of students are engaged in discussing material, jointly solving problems and jointly conducting simulated experiments. This is done under the supervision of a mentor. Suggestions for implementing this method in Israel will be discussed

  1. Shock wave attenuation in a micro-channel

    Science.gov (United States)

    Giordano, J.; Perrier, P.; Meister, L.; Brouillette, M.

    2018-05-01

    This work presents optical measurements of shock wave attenuation in a glass micro-channel. This transparent facility, with a cross section ranging from 1 mm× 150 μm to 1 mm× 500 μm, allowed for the use of high-speed schlieren videography to visualize the propagation of a shock wave within the entire micro-channel and to quantify velocity attenuation of the wave due to wall effects. In this paper, we present the experimental technique and the relevant data treatment we have used to increase the sensitivity of shock wave detection. Then, we compared our experimental results for different channel widths, lengths, and shock wave velocities with the analytical model for shock attenuation proposed by Russell (J Fluid Mech 27(2):305-314, 1967), which assumes laminar flow, and by Mirels (Attenuation in a shock tube due to unsteady-boundary-layer action, NACA Report 1333, 1957) for turbulent flow. We found that these models are inadequate to predict the observed data, owing to the presence of fully developed flow which violates the basic assumption of these models. The data are also compared with the empirical shock attenuation models proposed by Zeitoun (Phys Fluids 27(1):011701, 2015) and Deshpande and Puranik (Shock Waves 26(4):465-475, 2016), where better agreement is observed. Finally, we presented experimental data for the flow field behind the shock wave from measurements of the Mach wave angle which shows globally decreasing flow Mach numbers due to viscous wall effects.

  2. Gene × physical activity interactions in obesity

    DEFF Research Database (Denmark)

    Ahmad, Shafqat; Rukh, Gull; Varga, Tibor V

    2013-01-01

    Numerous obesity loci have been identified using genome-wide association studies. A UK study indicated that physical activity may attenuate the cumulative effect of 12 of these loci, but replication studies are lacking. Therefore, we tested whether the aggregate effect of these loci is diminished...... in adults of European ancestry reporting high levels of physical activity. Twelve obesity-susceptibility loci were genotyped or imputed in 111,421 participants. A genetic risk score (GRS) was calculated by summing the BMI-associated alleles of each genetic variant. Physical activity was assessed using self...... combined using meta-analysis weighted by cohort sample size. The meta-analysis yielded a statistically significant GRS × physical activity interaction effect estimate (Pinteraction  = 0.015). However, a statistically significant interaction effect was only apparent in North American cohorts (n = 39...

  3. Detection and measurement of gamma-ray self-attenuation in plutonium residues

    International Nuclear Information System (INIS)

    Prettyman, T.H.; Foster, L.A.; Estep, R.J.

    1996-01-01

    A new method to correct for self-attenuation in gamma-ray assays of plutonium is presented. The underlying assumptions of the technique are based on a simple but accurate physical model of plutonium residues, particularly pyrochemical salts, in which it is assumed that the plutonium is divided into two portions, each of which can be treated separately from the standpoint of gamma-ray analysis: a portion that is in the form of plutonium metal shot; and a dilute portion that is mixed with the matrix. The performance of the technique is evaluated using assays of plutonium residues by tomographic gamma scanning at the Los Alamos Plutonium Facility. The ability of the method to detect saturation conditions is examined

  4. Repeated Excessive Exercise Attenuates the Anti-Inflammatory Effects of Exercise in Older Men

    DEFF Research Database (Denmark)

    Sahl, Ronni E.; Andersen, Peter R.; Gronbaek, Katja

    2017-01-01

    Introduction/Purpose: A number of studies have investigated the effect of training with a moderate exercise dose (3–6 h/weekly) on the inflammatory profile in blood, and the data are inconsistent. Cross-sectional studies indicate a positive effect of physical activity level on inflammation levels...... inflammation, but the higher plasma IL-6 concentration concurrent with a trend toward higher insulin resistance and decreased VO2peak implies that the excessive amount of exercise probably attenuated the possible potential anti-inflammatory effects of exercise....... and risk of metabolic disease. However, it is not clear whether this may be dose dependent and if very prolonged repeated exercise therefore may be beneficial for low-grade inflammation. Based on this we studied how excessive repeated prolonged exercise influenced low-grade inflammation and adipose tissue...

  5. HMB attenuates muscle loss during sustained energy deficit induced by calorie restriction and endurance exercise.

    Science.gov (United States)

    Park, Bong-Sup; Henning, Paul C; Grant, Samuel C; Lee, Won Jun; Lee, Sang-Rok; Arjmandi, Bahram H; Kim, Jeong-Su

    2013-12-01

    To investigate the efficacy and underlying mechanisms of β-hydroxy-β-methylbutyrate (HMB) on body composition, muscle mass and physical performance under catabolic versus normal training conditions. Mice were divided into four groups (n=10/group): (1) ALT=ad libitum+trained (1 h/d for 3 d/wk); (2) ALTH=ALT+HMB (0.5 g/kg BW/d); (3) C=calorie restricted (-30%)+trained (6 h/d, 6 d/wk); and (4) CH=C+HMB. Repeated in vivo assessments included body composition, grip strength and sensorimotor coordination before and after the experimental protocol, while in vitro analyses included muscle wet weights, expression of selected genes and proteins regulating muscle mass, and myofiber cross-sectional area. ANOVAs were used with significance set at pHMB improves body composition and sensorimotor function during normal training and attenuates muscle mass and strength loss during catabolic conditions. © 2013.

  6. Physics revelations

    International Nuclear Information System (INIS)

    Sutton, Christine

    1994-01-01

    Erice must be not only one of the most picturesque settings for a conference on history, but also one of the most appropriate, founded so the legends say more than 3000 years ago. Particle physics, by contrast, is strikingly modern, but the Ettore Majorana Centre at Erice was a fitting location for physicists to gather and discuss their subject in the International Conference on the History of Original Ideas and Basic Discoveries in Particle Physics, from 29 July to 3 August. Particle physics can probably be said to have begun during the 1930s, a decade that saw Pauli's invention of the neutrino and Fermi's theory of beta-decay, as well as the discovery of the neutron, antimatter (the positron) and the first heavy lepton (the muon). In the relatively short time since then the subject has grown enormously, with many more disoveries, many new theoretical concepts, and many new experimental techniques

  7. Tokamak physics

    International Nuclear Information System (INIS)

    Haines, M.G.

    1984-01-01

    The physical conditions required for breakeven in thermonuclear fusion are derived, and the early conceptual ideas of magnetic confinement and subsequent development are followed, leading to present-day large scale tokamak experiments. Confinement and diffusion are developed in terms of particle orbits, whilst magnetohydrodynamic stability is discussed from energy considerations. From these ideas are derived the scaling laws that determine the physical size and parameters of this fusion configuration. It becomes clear that additional heating is required. However there are currently several major gaps in our understanding of experiments; the causes of anomalous electron energy loss and the major current disruption, the absence of the 'bootstrap' current and what physics determines the maximum plasma pressure consistent with stability. The understanding of these phenomena is a major challenge to plasma physicists. (author)

  8. Statistical physics

    CERN Document Server

    Guénault, Tony

    2007-01-01

    In this revised and enlarged second edition of an established text Tony Guénault provides a clear and refreshingly readable introduction to statistical physics, an essential component of any first degree in physics. The treatment itself is self-contained and concentrates on an understanding of the physical ideas, without requiring a high level of mathematical sophistication. A straightforward quantum approach to statistical averaging is adopted from the outset (easier, the author believes, than the classical approach). The initial part of the book is geared towards explaining the equilibrium properties of a simple isolated assembly of particles. Thus, several important topics, for example an ideal spin-½ solid, can be discussed at an early stage. The treatment of gases gives full coverage to Maxwell-Boltzmann, Fermi-Dirac and Bose-Einstein statistics. Towards the end of the book the student is introduced to a wider viewpoint and new chapters are included on chemical thermodynamics, interactions in, for exam...

  9. Physics activities

    International Nuclear Information System (INIS)

    1997-09-01

    As we move into the 21st Century, nuclear technology is on the verge of rejuvenation in advanced Member States and of expansion in developing Member States. The principal responsibilities of the IAEA are transferring technologies, co-ordinating scientific research, managing specialized projects and maintaining analytical quality control. The IAEA physics activities provide assistance with nuclear instrumentation, promote more effective utilization of research reactors and accelerators, and facilitate global co-operation in nuclear fusion research. These activities will help Member States improve their standards of living through the benefits of nuclear technology. This booklet presents a brief profile on the physics activities and involvement in these fields of the Physics Section, IAEA

  10. Higgs Physics

    CERN Document Server

    Pomarol, Alex

    2016-01-01

    With the discovery of the Higgs, we have access to a plethora of new physical processes that allow us to further test the SM and beyond. We show a convenient way to parametrize these physics using an effective theory for Higgs couplings, discussing the importance of the basis selection, predictions from a SM effective field theory, and possible ways to measure these couplings with special attention to the high-energy regime. Predictions from the MSSM and MCHM, with the comparison with data, are also provided.

  11. Theoretical physics

    International Nuclear Information System (INIS)

    Laval, G.

    1988-01-01

    The 1988 progress report of the theoretical Physics Center (Ecole Polytechnique, France), is presented. The research activities are carried out in the fields of the supersymmetry theory, the dynamic systems theory, the statistical mechanics, the plasma physics and the random media. Substantial improvements are obtained on dynamical system investigations. In the field theory, the definition of the Gross-Neveu model is achieved. However the construction of the non-abelian gauge theories and the conformal theories are the main research activities. Concerning Astrophysics, a three-dimensional gravitational code is obtained. The activities of each team, and the list of the published papers, congress communications and thesis are given [fr

  12. Mathematical physics

    CERN Document Server

    Geroch, Robert

    1985-01-01

    Mathematical Physics is an introduction to such basic mathematical structures as groups, vector spaces, topological spaces, measure spaces, and Hilbert space. Geroch uses category theory to emphasize both the interrelationships among different structures and the unity of mathematics. Perhaps the most valuable feature of the book is the illuminating intuitive discussion of the ""whys"" of proofs and of axioms and definitions. This book, based on Geroch's University of Chicago course, will be especially helpful to those working in theoretical physics, including such areas as relativity, particle

  13. LEP physics

    CERN Multimedia

    CERN. Geneva

    2001-01-01

    Various aspects of the physics made at LEP 1 and LEP 2 (precision measurements and searches for new physics will be discussed, from the fundamental motivations to the publication of the results. The techniques and tools developed and applied to reach the a priori goals of LEP (beam energy measurement, luminosity determination, event selection,...) will be described with a few meaningful examples. The high level techniques & bright ideas which allowed LEP to exceed by a large amount its design performance, and the consequences outcome will also be presented.

  14. Health physics

    International Nuclear Information System (INIS)

    Poston, J.W.

    1974-01-01

    In a series of eight lectures the following topics are dealt with: 1) interaction of radiation with matter; 2) radiation quantities and units; 3) the physical basis of radiation dosimetry; 4) detection and measurement of radiation; 5) mixed radiation dosimetry; 6) special methods in radiation dosimetry; 7) dose from electrons and beta rays; and 8) introduction to radiation biology

  15. Particle physics

    International Nuclear Information System (INIS)

    Kamal, Anwar

    2014-01-01

    Provides step-by-step derivations. Contains numerous tables and diagrams. Supports learning and teaching with numerous worked examples, questions and problems with answers. Sketches also the historical development of the subject. This textbook teaches particle physics very didactically. It supports learning and teaching with numerous worked examples, questions and problems with answers. Numerous tables and diagrams lead to a better understanding of the explanations. The content of the book covers all important topics of particle physics: Elementary particles are classified from the point of view of the four fundamental interactions. The nomenclature used in particle physics is explained. The discoveries and properties of known elementary particles and resonances are given. The particles considered are positrons, muon, pions, anti-protons, strange particles, neutrino and hadrons. The conservation laws governing the interactions of elementary particles are given. The concepts of parity, spin, charge conjugation, time reversal and gauge invariance are explained. The quark theory is introduced to explain the hadron structure and strong interactions. The solar neutrino problem is considered. Weak interactions are classified into various types, and the selection rules are stated. Non-conservation of parity and the universality of the weak interactions are discussed. Neutral and charged currents, discovery of W and Z bosons and the early universe form important topics of the electroweak interactions. The principles of high energy accelerators including colliders are elaborately explained. Additionally, in the book detectors used in nuclear and particle physics are described. This book is on the upper undergraduate level.

  16. Motorcycle Physics.

    Science.gov (United States)

    Engel, Chuck; Girard, Barbara

    1983-01-01

    At the end of a secondary school science study of mechanics, a summary lab uses a motorcycle to provide students with the chance to apply some of the concepts they have studied. Exercises from this motorcycle physics lab are discussed. (Author/JN)

  17. Physical conditions

    DEFF Research Database (Denmark)

    Nielsen, Birte Lindstrøm; Appleby, M.C.; Waran, N.K.

    2011-01-01

    The physical environment of an animal is sometimes altered if it is found to cause problems for animal welfare. These changes are commonly quite specific (making changes to space, food, water, aspects of housing design such as flooring, or to other environmental factors such as air quality) and may...

  18. Zombie physics

    Science.gov (United States)

    Ornes, Stephen

    2016-05-01

    What makes for a fun student project that provides useful results, a journal publication and a high-profile conference talk? Stephen Ornes describes how Alex Alemi and Matt Bierbaum spiced up their learning by mixing statistical physics with their love of zombie tales.

  19. Physics News

    CERN Multimedia

    Gianotti, F.

    In spite of the fact that real data will only come in the year 2006, this is a very busy and interesting time for Physics-related activities. A very short overview of these activities is given in this issue of the ATLAS News Letter, while the various topics will be described in more detail in the next issues. The Physics and Combined Performance groups are working in four main areas: 1) Assess the ATLAS potential for physics, with emphasis on new channels and ideas. Recent examples are Extra-dimensions, invisible Higgs decays, heavy ion physics, the expected potential of a "Super-LHC" running at a luminosity of 10^35, etc.. 2) Improve the understanding of the detector performance and optimise the reconstruction algorithms. Examples of issues in the pipeline are: can we tag charm-jet ? What can we gain in the jet energy resolution by combining the calorimeter and tracker information to reconstruct the jet energy ? 3) Follow detector changes and detector-related issues and monitor the impact on the perform...

  20. Atomic physics

    CERN Document Server

    Born, Max

    1969-01-01

    The Nobel Laureate's brilliant exposition of the kinetic theory of gases, elementary particles, the nuclear atom, wave-corpuscles, atomic structure and spectral lines, electron spin and Pauli's principle, quantum statistics, molecular structure and nuclear physics. Over 40 appendices, a bibliography, numerous figures and graphs.

  1. Unifying Physics

    Science.gov (United States)

    Goradia, Shantilal

    2013-04-01

    Century old GR fails to unify quantum physics, nuclear force or distinguish between the mass of living bodies from inert mass. Probabilistic gravity [1] explains strong coupling (nuclear force). The natural log of the age of the universe, 10E60 in Planck times, equaling 137 (1/Alpha) extends physics to deeper science, if we stand on the shoulders of giants like Feynman and Gamow. Implications of [1] are that it is not the earth, but M and S numbers of the particles of the earth are remotely interacting with corresponding numbers of the particles of the moon and the sun respectively, neglecting other heavenly bodies in this short draft. This new physics is likely to enable creative scientific minds to throw light on a theoretical basis for an otherwise arbitrary cosmological constant, uniformity of microwave background, further vindication of Boltzmann, quantum informatics, Einstein’s later publicized views and more, eliminating the need to spend money for implicitly nonexistent quantum gravity and graviton.[4pt] [1] Journal of Physical Science and Applications 2 (7) (2012) 265-268.

  2. Astroparticle Physics

    OpenAIRE

    Magnussen, Norbert

    1999-01-01

    In this astro-particle lecture course I shall try to emphasize evidence of the new physics which we have in cosmological and astrophysical data. This includes support of the inflationary model, necessity of dark energy and of non-baryonic dark matter, the Grizen-Zatsepin-Kuzmin puzzle of the ultra-high energy cosmic rays.

  3. Physical Linguistics.

    Science.gov (United States)

    Tice, Bradley S.

    Physical linguistics is defined as the use of treatments from the field of speech pathology to enhance first and second language production in healthy individuals, resulting in increased quality and strength of phonation and articulation. A series of exercises for treating dysarthria (weakness, paralysis, discoordination, primary and secondary…

  4. Physics 87

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    A historical review about the physical research in the years 1687, 1887, and 1987 is given. In this connection the confirmation of Newton's Principia by Halley, the Michelson experiment, the discovery of radiowaves by Hertz, and the recent observation of a supernova are mentioned. (HSI).

  5. Physical properties

    International Nuclear Information System (INIS)

    Anon.

    1976-01-01

    Research activities into the physical properties of metals and ceramics at Lawrence Berkeley Laboratory during 1976 are reported. Topics covered include: high field superconductivity; microstructure and mechanical behavior of ceramics, glass-metal, and ceramic-metal systems; high temperature reactions; relation of microstructure to properties in ceramics; and structure and properties of carbon materials and composite materials

  6. "Explosive" Physics.

    Science.gov (United States)

    Kienzynski, Mark J.

    1998-01-01

    Describes a physics demonstration in which two-liter plastic bottles can be used to show how force relates to pressure and area. Identical drinking straws are launched out of similar plastic bottles with different-sized openings. This demonstration proves qualitatively that pressure is inversely proportional to the area exposed to an object when a…

  7. Nuclear physics

    International Nuclear Information System (INIS)

    Guzman B, O.; Vallejo M, J.I.; Cardenas C, H.F.

    1989-01-01

    A historical review of the evolution of the Nuclear Physics Section at the IAN is presented along the 30 years of existence of the Institute. Objectives, structure, programs and goal are historically examined. Present status of the section and its projection on national development is also analyzed

  8. Radiation physics

    International Nuclear Information System (INIS)

    Robles, Ana Maria

    1994-01-01

    A brief historical review of radioactivity, nuclear physics, atomic nucleus, nuclear models,nuclear instability, mass defect, nuclear transmutations, radioactivity phenomenon, Batemand equations, decay constants, half life, mean life, des integration rates,units.Alpha, Beta and gamma decay, other less probably encountered decay modes.Bibliography

  9. Higgs physics

    Indian Academy of Sciences (India)

    The theoretical aspects of the physics of Higgs bosons are reviewed focussing on the elements that are relevant for the production and detection at present hadron colliders. After briefly summarizing the basics of electroweak symmetry breaking in the Standard Model, the Higgs production at the LHC and at the Tevatron is ...

  10. After physics

    CERN Document Server

    Albert, David Z

    2015-01-01

    After Physics presents ambitious new essays about some of the deepest questions at the foundations of physics, by the physicist and philosopher David Albert. The book’s title alludes to the close connections between physics and metaphysics, much in evidence throughout these essays. It also alludes to the work of imagining what it would be like for the project of physical science—considered as an investigation into the fundamental laws of nature—to be complete. Albert argues that the difference between the past and the future—traditionally regarded as a matter for metaphysical or conceptual or linguistic or phenomenological analysis—can be understood as a mechanical phenomenon of nature. In another essay he contends that all versions of quantum mechanics that are compatible with the special theory of relativity make it impossible, even in principle, to present the entirety of what can be said about the world as a narrative sequence of “befores” and “afters.” Any sensible and realistic way of...

  11. Flipped Physics

    Science.gov (United States)

    Kettle, Maria

    2013-01-01

    This paper defines flipped learning and then examines its practical implementation in AS and A2 level physics classes, that is, classes for 16-18 year olds. The effect of this teaching style on student learning behaviour and its impact on test results are evaluated. The paper recounts the difficulties of implementing it and evaluates student…

  12. 'KAON' physics

    International Nuclear Information System (INIS)

    Fearing, H.W.

    1989-07-01

    Plans and prospects are described for KAON, a proposal by TRIUMF to build an advanced hadron facility or kaon factory. The machine would be a 30 GeV high intensity proton machine producing intense beams of kaons, pions, muons, antiprotons, and neutrinos. Some of the interesting physics which could be done with such a machine is described. (Author) 11 refs., 2 figs., tab

  13. Nuclear physics

    International Nuclear Information System (INIS)

    1990-01-01

    This work describes the actual situation of nuclear physics in Brazil as well as its perspectives of developments and real needs in the next decade. It discusses the main projects and the financing of brazilian research groups and Universities. (A.C.A.S.)

  14. Physics of Ultrasound. Chapter 12

    Energy Technology Data Exchange (ETDEWEB)

    Lacefield, J. C. [University of Western Ontario, London (Canada)

    2014-09-15

    Ultrasound is the most commonly used diagnostic imaging modality, accounting for approximately 25% of all imaging examinations performed worldwide at the beginning of the 21st century. The success of ultrasound may be attributed to a number of attractive characteristics, including the relatively low cost and portability of an ultrasound scanner, the non-ionizing nature of ultrasound waves, the ability to produce real time images of blood flow and moving structures such as the beating heart, and the intrinsic contrast among soft tissue structures that is achieved without the need for an injected contrast agent. The latter characteristic enables ultrasound to be used for a wide range of medical applications, which historically have primarily included cardiac and vascular imaging, imaging of the abdominal organs and, most famously, in utero imaging of the developing fetus. Ongoing technological improvements continue to expand the use of ultrasound for many applications, including cancer imaging, musculoskeletal imaging, ophthalmology and others. The term ultrasound refers specifically to acoustic waves at frequencies greater than the maximum frequency audible to humans, which is nominally 20 kHz. Diagnostic imaging is generally performed using ultrasound in the frequency range of 2–15 MHz. The choice of frequency is dictated by a trade off between spatial resolution and penetration depth, since higher frequency waves can be focused more tightly but are attenuated more rapidly by tissue. The information contained in an ultrasonic image is influenced by the physical processes underlying propagation, reflection and attenuation of ultrasound waves in tissue.

  15. Attenuation and velocity dispersion in the exploration seismic frequency band

    Science.gov (United States)

    Sun, Langqiu

    In an anelastic medium, seismic waves are distorted by attenuation and velocity dispersion, which depend on petrophysical properties of reservoir rocks. The effective attenuation and velocity dispersion is a combination of intrinsic attenuation and apparent attenuation due to scattering, transmission response, and data acquisition system. Velocity dispersion is usually neglected in seismic data processing partly because of insufficient observations in the exploration seismic frequency band. This thesis investigates the methods of measuring velocity dispersion in the exploration seismic frequency band and interprets the velocity dispersion data in terms of petrophysical properties. Broadband, uncorrelated vibrator data are suitable for measuring velocity dispersion in the exploration seismic frequency band, and a broad bandwidth optimizes the observability of velocity dispersion. Four methods of measuring velocity dispersion in uncorrelated vibrator VSP data are investigated, which are the sliding window crosscorrelation (SWCC) method, the instantaneous phase method, the spectral decomposition method, and the cross spectrum method. Among them, the SWCC method is a new method and has satisfactory robustness, accuracy, and efficiency. Using the SWCC method, velocity dispersion is measured in the uncorrelated vibrator VSP data from three areas with different geological settings, i.e., Mallik gas hydrate zone, McArthur River uranium mines, and Outokumpu crystalline rocks. The observed velocity dispersion is fitted to a straight line with respect to log frequency for a constant (frequency-independent) Q value. This provides an alternative method for calculating Q. A constant Q value does not directly link to petrophysical properties. A modeling study is implemented for the Mallik and McArthur River data to interpret the velocity dispersion observations in terms of petrophysical properties. The detailed multi-parameter petrophysical reservoir models are built according to

  16. The ultraviolet attenuation law in backlit spiral galaxies

    International Nuclear Information System (INIS)

    Keel, William C.; Manning, Anna M.; Holwerda, Benne W.; Lintott, Chris J.; Schawinski, Kevin

    2014-01-01

    The effective extinction law (attenuation behavior) in galaxies in the emitted ultraviolet (UV) regime is well known only for actively star-forming objects and combines effects of the grain properties, fine structure in the dust distribution, and relative distributions of stars and dust. We use Galaxy Evolution Explorer, XMM Optical Monitor, and Hubble Space Telescope (HST) data to explore the UV attenuation in the outer parts of spiral disks which are backlit by other UV-bright galaxies, starting with the candidate list of pairs provided by Galaxy Zoo participants. New optical images help to constrain the geometry and structure of the target galaxies. Our analysis incorporates galaxy symmetry, using non-overlapping regions of each galaxy to derive error estimates on the attenuation measurements. The entire sample has an attenuation law across the optical and UV that is close to the Calzetti et al. form; the UV slope for the overall sample is substantially shallower than found by Wild et al., which is a reasonable match to the more distant galaxies in our sample but not to the weighted combination including NGC 2207. The nearby, bright spiral NGC 2207 alone gives an accuracy almost equal to the rest of our sample, and its outer arms have a very low level of foreground starlight. Thus, this widespread, fairly 'gray' law can be produced from the distribution of dust alone, without a necessary contribution from differential escape of stars from dense clouds. Our results indicate that the extrapolation needed to compare attenuation between backlit galaxies at moderate redshifts from HST data, and local systems from Sloan Digital Sky Survey and similar data, is mild enough to allow the use of galaxy overlaps to trace the cosmic history of dust in galaxies. For NGC 2207, HST data in the near-UV F336W band show that the covering factor of clouds with small optical attenuation becomes a dominant factor farther into the UV, which opens the possibility that

  17. The Ultraviolet Attenuation Law in Backlit Spiral Galaxies

    Science.gov (United States)

    Keel, William C.; Manning, Anna M.; Holwerda, Benne W.; Lintott, Chris J.; Schawinski, Kevin

    2014-02-01

    The effective extinction law (attenuation behavior) in galaxies in the emitted ultraviolet (UV) regime is well known only for actively star-forming objects and combines effects of the grain properties, fine structure in the dust distribution, and relative distributions of stars and dust. We use Galaxy Evolution Explorer, XMM Optical Monitor, and Hubble Space Telescope (HST) data to explore the UV attenuation in the outer parts of spiral disks which are backlit by other UV-bright galaxies, starting with the candidate list of pairs provided by Galaxy Zoo participants. New optical images help to constrain the geometry and structure of the target galaxies. Our analysis incorporates galaxy symmetry, using non-overlapping regions of each galaxy to derive error estimates on the attenuation measurements. The entire sample has an attenuation law across the optical and UV that is close to the Calzetti et al. form; the UV slope for the overall sample is substantially shallower than found by Wild et al., which is a reasonable match to the more distant galaxies in our sample but not to the weighted combination including NGC 2207. The nearby, bright spiral NGC 2207 alone gives an accuracy almost equal to the rest of our sample, and its outer arms have a very low level of foreground starlight. Thus, this widespread, fairly "gray" law can be produced from the distribution of dust alone, without a necessary contribution from differential escape of stars from dense clouds. Our results indicate that the extrapolation needed to compare attenuation between backlit galaxies at moderate redshifts from HST data, and local systems from Sloan Digital Sky Survey and similar data, is mild enough to allow the use of galaxy overlaps to trace the cosmic history of dust in galaxies. For NGC 2207, HST data in the near-UV F336W band show that the covering factor of clouds with small optical attenuation becomes a dominant factor farther into the UV, which opens the possibility that widespread

  18. The ultraviolet attenuation law in backlit spiral galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Keel, William C. [Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487 (United States); Manning, Anna M. [Stennis Space Center, MS 39522 (United States); Holwerda, Benne W. [ESA-ESTEC, Keplerlaan 1, 2201-AZ Noordwijk (Netherlands); Lintott, Chris J. [Astrophysics, Oxford University, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Schawinski, Kevin, E-mail: wkeel@ua.edu, E-mail: ammanning@bama.ua.edu, E-mail: bholwerd@rssd.esa.int, E-mail: Twitter@BenneHolwerda, E-mail: cjl@astro.ox.ac.uk, E-mail: Twitter@chrislintott, E-mail: kevin.schawinski@phys.ethz.ch, E-mail: Twitter@kevinschawinski [Institute for Astronomy, ETH Zürich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland)

    2014-02-01

    The effective extinction law (attenuation behavior) in galaxies in the emitted ultraviolet (UV) regime is well known only for actively star-forming objects and combines effects of the grain properties, fine structure in the dust distribution, and relative distributions of stars and dust. We use Galaxy Evolution Explorer, XMM Optical Monitor, and Hubble Space Telescope (HST) data to explore the UV attenuation in the outer parts of spiral disks which are backlit by other UV-bright galaxies, starting with the candidate list of pairs provided by Galaxy Zoo participants. New optical images help to constrain the geometry and structure of the target galaxies. Our analysis incorporates galaxy symmetry, using non-overlapping regions of each galaxy to derive error estimates on the attenuation measurements. The entire sample has an attenuation law across the optical and UV that is close to the Calzetti et al. form; the UV slope for the overall sample is substantially shallower than found by Wild et al., which is a reasonable match to the more distant galaxies in our sample but not to the weighted combination including NGC 2207. The nearby, bright spiral NGC 2207 alone gives an accuracy almost equal to the rest of our sample, and its outer arms have a very low level of foreground starlight. Thus, this widespread, fairly 'gray' law can be produced from the distribution of dust alone, without a necessary contribution from differential escape of stars from dense clouds. Our results indicate that the extrapolation needed to compare attenuation between backlit galaxies at moderate redshifts from HST data, and local systems from Sloan Digital Sky Survey and similar data, is mild enough to allow the use of galaxy overlaps to trace the cosmic history of dust in galaxies. For NGC 2207, HST data in the near-UV F336W band show that the covering factor of clouds with small optical attenuation becomes a dominant factor farther into the UV, which opens the possibility that

  19. Viscothermal Coupling Effects on Sound Attenuation in Concentrated Colloidal Dispersions.

    Science.gov (United States)

    Han, Wei

    1995-11-01

    This thesis describes a Unified Coupled Phase Continuum (UCPC) model to analyze sound propagation through aerosols, emulsions and suspensions in terms of frequency dependent attenuation coefficient and sound speed. Expressions for the viscous and thermal coupling coefficients explicitly account for the effects of particle size, shape factor, orientation as well as concentration and the sound frequency. The UCPC model also takes into account the intrinsic acoustic absorption within the fluid medium due to its viscosity and heat conductivity. The effective complex wave number as a function of frequency is derived. A frequency- and concentration-dependent complex Nusselt number for the interfacial thermal coupling coefficient is derived using an approximate similarity between the 'viscous skin drag' and 'heat conduction flux' associated with the discontinuous suspended phase, on the basis of a cell model. The theoretical predictions of attenuation spectra provide satisfactory agreement with reported experimental data on two concentrated suspensions (polystyrene latex and kaolin pigment), two concentrated emulsions (toluene -in-water, n-hexadecane-in-water), and two aerosols (oleic acid droplets-in-nitrogen, alumina-in-air), covering a wide range of relative magnitudes (from 10^ {-3} to 10^{3}) of thermal versus viscous contributions, for dispersed phase volume fractions as high as 50%. The relative differences between the additive result of separate viscous and thermal loss estimates and combined viscothermal absorption results are also presented. Effects of particle shape on viscous attenuation of sound in concentrated suspensions of non-spherical clay particles are studied. Attenuation spectra for 18 frequencies from 3 to 100 MHz are measured and analyzed for eleven kaolin clay slurries with solid concentrations ranging from 0.6% to 35% (w/w). A modified viscous drag coefficient that considers frequency, concentration, particle size, shape and orientation of

  20. Evaluation of attenuating materials: model for the distribution of scattered radiation

    International Nuclear Information System (INIS)

    Costa, Paulo R.

    1996-01-01

    A mathematical model for the behaviour of the distribution of photon scattered by attenuating media is presented. Shielding barriers or attenuating materials used in tests of quality control in radiology are proposed. Comparative results for Lucite are reported

  1. Evaluation of downwelling diffuse attenuation coefficient algorithms in the Red Sea

    KAUST Repository

    Tiwari, Surya Prakash; Yellepeddi, Sarma B.; Jones, Burton

    2016-01-01

    to comprehend the diffuse attenuation coefficient and its relationship with in situ properties. Two apparent optical properties, spectral remote sensing reflectance (Rrs) and the downwelling diffuse attenuation coefficient (Kd), are calculated from vertical

  2. Modeled Radar Attenuation Rate Profile at the Vostok 5G Ice Core Site, Antarctica, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides a modeled radar attenuation rate profile, showing the predicted contributions from pure ice and impurities to radar attenuation at the Vostok...

  3. Optimization of coronary optical coherence tomography imaging using the attenuation-compensated technique: a validation study.

    NARCIS (Netherlands)

    Teo, Jing Chun; Foin, Nicolas; Otsuka, Fumiyuki; Bulluck, Heerajnarain; Fam, Jiang Ming; Wong, Philip; Low, Fatt Hoe; Leo, Hwa Liang; Mari, Jean-Martial; Joner, Michael; Girard, Michael J A; Virmani, Renu; Bezerra, HG.; Costa, MA.; Guagliumi, G.; Rollins, AM.; Simon, D.; Gutiérrez-Chico, JL.; Alegría-Barrero, E.; Teijeiro-Mestre, R.; Chan, PH.; Tsujioka, H.; de Silva, R.; Otsuka, F.; Joner, M.; Prati, F.; Virmani, R.; Narula, J.; Members, WC.; Levine, GN.; Bates, ER.; Blankenship, JC.; Bailey, SR.; Bittl, JA.; Prati, F.; Guagliumi, G.; Mintz, G.S.; Costa, Marco; Regar, E.; Akasaka, T.; Roleder, T.; Jąkała, J.; Kałuża, GL.; Partyka, Ł.; Proniewska, K.; Pociask, E.; Girard, MJA.; Strouthidis, NG.; Ethier, CR.; Mari, JM.; Mari, JM.; Strouthidis, NG.; Park, SC.; Girard, MJA.; van der Lee, R.; Foin, N.; Otsuka, F.; Wong, P.K.; Mari, J-M.; Joner, M.; Nakano, M.; Vorpahl, M.; Otsuka, F.; Taniwaki, M.; Yazdani, SK.; Finn, AV.; Nakano, M.; Yahagi, K.; Yamamoto, H.; Taniwaki, M.; Otsuka, F.; Ladich, ER.; Girard, MJ.; Ang, M.; Chung, CW.; Farook, M.; Strouthidis, N.; Mehta, JS.; Foin, N.; Mari, JM.; Nijjer, S.; Sen, S.; Petraco, R.; Ghione, M.; Liu, X.; Kang, JU.; Virmani, R.; Kolodgie, F.D.; Burke, AP.; Farb, A.; Schwartz, S.M.; Yahagi, K.; Kolodgie, F.D.; Otsuka, F.; Finn, AV.; Davis, HR.; Joner, M.; Kume, T.; Akasaka, T.; Kawamoto, T.; Watanabe, N.; Toyota, E.; Neishi, Y.; Rieber, J.; Meissner, O.; Babaryka, G.; Reim, S.; Oswald, M.E.; Koenig, A.S.; Tearney, G. J.; Regar, E.; Akasaka, T.; Adriaenssens, T.; Barlis, P.; Bezerra, HG.; Yabushita, H.; Bouma, BE.; Houser, S. L.; Aretz, HT.; Jang, I-K.; Schlendorf, KH.; Guo, J.; Sun, L.; Chen, Y.D.; Tian, F.; Liu, HB.; Chen, L.; Kawasaki, M.; Bouma, BE.; Bressner, J. E.; Houser, S. L.; Nadkarni, S. K.; MacNeill, BD.; Jansen, CHP.; Onthank, DC.; Cuello, F.; Botnar, RM.; Wiethoff, AJ.; Warley, A.; von Birgelen, C.; Hartmann, A. M.; Kubo, T.; Akasaka, T.; Shite, J.; Suzuki, T.; Uemura, S.; Yu, B.; Habara, M.; Nasu, K.; Terashima, M.; Kaneda, H.; Yokota, D.; Ko, E.; Virmani, R.; Burke, AP.; Kolodgie, F.D.; Farb, A.; Takarada, S.; Imanishi, T.; Kubo, T.; Tanimoto, T.; Kitabata, H.; Nakamura, N.; Hattori, K.; Ozaki, Y.; Ismail, TF.; Okumura, M.; Naruse, H.; Kan, S.; Nishio, R.; Shinke, T.; Otake, H.; Nakagawa, M.; Nagoshi, R.; Inoue, T.; Sinclair, H.D.; Bourantas, C.; Bagnall, A.; Mintz, G.S.; Kunadian, V.; Tearney, G. J.; Yabushita, H.; Houser, S. L.; Aretz, HT.; Jang, I-K.; Schlendorf, KH.; van Soest, G.; Goderie, T.; Regar, E.; Koljenović, S.; Leenders, GL. van; Gonzalo, N.; Xu, C.; Schmitt, JM.; Carlier, SG.; Virmani, R.; van der Meer, FJ; Faber, D.J.; Sassoon, DMB.; Aalders, M.C.; Pasterkamp, G.; Leeuwen, TG. van; Schmitt, JM.; Knuttel, A.; Yadlowsky, M.; Eckhaus, MA.; Karamata, B.; Laubscher, M.; Leutenegger, M.; Bourquin, S.; Lasser, T.; Lambelet, P.; Vermeer, K.A.; Mo, J.; Weda, J.J.A.; Lemij, H.G.; Boer, JF. de

    2016-01-01

    PURPOSE To optimize conventional coronary optical coherence tomography (OCT) images using the attenuation-compensated technique to improve identification of plaques and the external elastic lamina (EEL) contour. METHOD The attenuation-compensated technique was optimized via manipulating contrast

  4. Pomeron physics

    International Nuclear Information System (INIS)

    Fujisaki, H.

    1986-01-01

    Our discussion is primarily confined to the asymptopia. From the phenomenological point of view, diffraction at presently available high energies can be reasonably well described in terms of the bare simplepole pomeron with the intercept at t=O slightly above unity. From the theoretical point of view, however, the self-consistent explanation of diffraction at the asymptopia inevitably necessitates the clothed physical pomeron with the unit intercept at t=O. The bare pomeron is built up from the normal reggeon through dual topological unitarization. Comparitively, the clothed physical pomeron is generated by multidiffractive unitarization of the bare pomeron. The clothed pomeron is often referred to as the geometrical pomeron (GP). The GP is universal in the sense that the asymptotic behaviour of the clothed pomeron is independent of the fine details of dynamics building up and unitarizing the bare pomeron. All unusual features of the physical pomeron are commonly inherent in universality of the GP which plays the role of the most typical guiding principle in pomeron physics. If the GP parmeterization is continued in t to beyond the lowest threshold, however, t-channel unitarity is seriously violated because of the hard branching nature. It is then of importance to investigate whether or not the GP universality is self-consistently guaranteed not only from the s-channel point of view but also from the t-channel point of view, and how the universal GP dynamically affects normal reggeons through the repeated pomeron exchange. Solutions to these key questions are summarized after geometrodynamical parts of a series of our works on pomeron physics is discussed

  5. Modelling the attenuation in the ATHENA finite elements code for the ultrasonic testing of austenitic stainless steel welds.

    Science.gov (United States)

    Chassignole, B; Duwig, V; Ploix, M-A; Guy, P; El Guerjouma, R

    2009-12-01

    Multipass welds made in austenitic stainless steel, in the primary circuit of nuclear power plants with pressurized water reactors, are characterized by an anisotropic and heterogeneous structure that disturbs the ultrasonic propagation and makes ultrasonic non-destructive testing difficult. The ATHENA 2D finite element simulation code was developed to help understand the various physical phenomena at play. In this paper, we shall describe the attenuation model implemented in this code to give an account of wave scattering phenomenon through polycrystalline materials. This model is in particular based on the optimization of two tensors that characterize this material on the basis of experimental values of ultrasonic velocities attenuation coefficients. Three experimental configurations, two of which are representative of the industrial welds assessment case, are studied in view of validating the model through comparison with the simulation results. We shall thus provide a quantitative proof that taking into account the attenuation in the ATHENA code dramatically improves the results in terms of the amplitude of the echoes. The association of the code and detailed characterization of a weld's structure constitutes a remarkable breakthrough in the interpretation of the ultrasonic testing on this type of component.

  6. Radiation Attenuation and Stability of ClearView Radiation Shielding TM-A Transparent Liquid High Radiation Shield.

    Science.gov (United States)

    Bakshi, Jayeesh

    2018-04-01

    Radiation exposure is a limiting factor to work in sensitive environments seen in nuclear power and test reactors, medical isotope production facilities, spent fuel handling, etc. The established choice for high radiation shielding is lead (Pb), which is toxic, heavy, and abidance by RoHS. Concrete, leaded (Pb) bricks are used as construction materials in nuclear facilities, vaults, and hot cells for radioisotope production. Existing transparent shielding such as leaded glass provides minimal shielding attenuation in radiotherapy procedures, which in some cases is not sufficient. To make working in radioactive environments more practicable while resolving the lead (Pb) issue, a transparent, lightweight, liquid, and lead-free high radiation shield-ClearView Radiation Shielding-(Radium Incorporated, 463 Dinwiddie Ave, Waynesboro, VA). was developed. This paper presents the motivation for developing ClearView, characterization of certain aspects of its use and performance, and its specific attenuation testing. Gamma attenuation testing was done using a 1.11 × 10 Bq Co source and ANSI/HPS-N 13.11 standard. Transparency with increasing thickness, time stability of liquid state, measurements of physical properties, and performance in freezing temperatures are reported. This paper also presents a comparison of ClearView with existing radiation shields. Excerpts from LaSalle nuclear power plant are included, giving additional validation. Results demonstrated and strengthened the expected performance of ClearView as a radiation shield. Due to the proprietary nature of the work, some information is withheld.

  7. EDITORIAL: Physics competitions Physics competitions

    Science.gov (United States)

    Jordens, H.; Mathelitsch, L.

    2009-11-01

    1. Physics competitions: aims and realizations One aim of physics competitions is to increase the interest of young students, primarily at upper secondary level, to physics and natural sciences in general. A competition has motivational aspects known usually from sports events or games—comparing one's own ability with others, of course with the desire to be better and to win. If competitions reach nationwide and even international levels, additional stimulation is created. Competitions provide greatest attraction to possible winners, to the group of gifted people in a particular field. This implies that science contests are excellent tools for the promotion of talented students. Traditional teaching has been shown to have problems in supporting this group of students. Very often teachers are overstretched with the demands of teaching both low- and high-level students. Extracurricular activities are therefore a good chance to relieve the teacher, and to give talented students the opportunity for appropriate training and challenge. The competitions, however, have a broader impact and address more young people than one might guess from the statements above. Training courses and selection at school level give a larger group of students extra and, to some extent, complimentary education in physics. The degree of complexity of the tasks corresponds very often to the standards of the next level of education in the school system. Interestingly, many physics competitions have their origin in countries beyond the former Iron Curtain. They started as regional and national tournaments, were joined by neighbouring countries and have grown, in some cases, to events with participants from more than 80 countries. Although the features mentioned above are common to the different competitions, there are distinct differences between them [1]. The International Physics Olympiad (IPhO) is the oldest international physics competition for students at upper secondary level [2]. It dates

  8. Theoretical determination of gamma spectrometry systems efficiency based on probability functions. Application to self-attenuation correction factors

    Energy Technology Data Exchange (ETDEWEB)

    Barrera, Manuel, E-mail: manuel.barrera@uca.es [Escuela Superior de Ingeniería, University of Cadiz, Avda, Universidad de Cadiz 10, 11519 Puerto Real, Cadiz (Spain); Suarez-Llorens, Alfonso [Facultad de Ciencias, University of Cadiz, Avda, Rep. Saharaui s/n, 11510 Puerto Real, Cadiz (Spain); Casas-Ruiz, Melquiades; Alonso, José J.; Vidal, Juan [CEIMAR, University of Cadiz, Avda, Rep. Saharaui s/n, 11510 Puerto Real, Cádiz (Spain)

    2017-05-11

    A generic theoretical methodology for the calculation of the efficiency of gamma spectrometry systems is introduced in this work. The procedure is valid for any type of source and detector and can be applied to determine the full energy peak and the total efficiency of any source-detector system. The methodology is based on the idea of underlying probability of detection, which describes the physical model for the detection of the gamma radiation at the particular studied situation. This probability depends explicitly on the direction of the gamma radiation, allowing the use of this dependence the development of more realistic and complex models than the traditional models based on the point source integration. The probability function that has to be employed in practice must reproduce the relevant characteristics of the detection process occurring at the particular studied situation. Once the probability is defined, the efficiency calculations can be performed in general by using numerical methods. Monte Carlo integration procedure is especially useful to perform the calculations when complex probability functions are used. The methodology can be used for the direct determination of the efficiency and also for the calculation of corrections that require this determination of the efficiency, as it is the case of coincidence summing, geometric or self-attenuation corrections. In particular, we have applied the procedure to obtain some of the classical self-attenuation correction factors usually employed to correct for the sample attenuation of cylindrical geometry sources. The methodology clarifies the theoretical basis and approximations associated to each factor, by making explicit the probability which is generally hidden and implicit to each model. It has been shown that most of these self-attenuation correction factors can be derived by using a common underlying probability, having this probability a growing level of complexity as it reproduces more precisely

  9. Attenuation of monkeypox virus by deletion of genomic regions

    Science.gov (United States)

    Lopera, Juan G.; Falendysz, Elizabeth A.; Rocke, Tonie E.; Osorio, Jorge E.

    2015-01-01

    Monkeypox virus (MPXV) is an emerging pathogen from Africa that causes disease similar to smallpox. Two clades with different geographic distributions and virulence have been described. Here, we utilized bioinformatic tools to identify genomic regions in MPXV containing multiple virulence genes and explored their roles in pathogenicity; two selected regions were then deleted singularly or in combination. In vitro and in vivostudies indicated that these regions play a significant role in MPXV replication, tissue spread, and mortality in mice. Interestingly, while deletion of either region led to decreased virulence in mice, one region had no effect on in vitro replication. Deletion of both regions simultaneously also reduced cell culture replication and significantly increased the attenuation in vivo over either single deletion. Attenuated MPXV with genomic deletions present a safe and efficacious tool in the study of MPX pathogenesis and in the identification of genetic factors associated with virulence.

  10. Antioxidant treatment attenuates lactate production in diabetic nephropathy

    DEFF Research Database (Denmark)

    Laustsen, Christoffer; Nielsen, Per Mose; Stokholm Nørlinger, Thomas

    2017-01-01

    -IDEAL spiral sequence. Untreated diabetic rats showed increased renal lactate production compared with that shown by the controls. However, chronic TEMPOL treatment significantly attenuated diabetes-induced lactate production. No significant effects of diabetes or TEMPOL were observed on [13C]alanine levels......, indicating an intact glucose-alanine cycle, or [13C]bicarbonate, indicating normal flux through the Krebs cycle. In conclusion, this study demonstrates that diabetes-induced pseudohypoxia, as indicated by an increased lactate-to-pyruvate ratio, is significantly attenuated by antioxidant treatment......The early progression of diabetic nephropathy is notoriously difficult to detect and quantify before the occurrence of substantial histological damage. Recently, hyperpolarized [1-13C]pyruvate has demonstrated increased lactate production in the kidney early after the onset of diabetes, implying...

  11. ASSESSING AEROBIC NATURAL ATTENUATION OF TRICHLOROETHENE AT FOUR DOE SITES

    International Nuclear Information System (INIS)

    Koelsch, Michael C.; Starr, Robert C.; Sorenson, Kent S. Jr.

    2005-01-01

    A 3-year Department of Energy Environmental Science Management Program (EMSP) project is currently investigating natural attenuation of trichloroethane (TCE) in aerobic groundwater. This presentation summarizes the results of a screening process to identify TCE plumes at DOE facilities that are suitable for assessing the rate of TCE cometabolism under aerobic conditions. In order to estimate aerobic degradation rates, plumes had to meet the following criteria: TCE must be present in aerobic groundwater, a conservative co-contaminant must be present and have approximately the same source as TCE, and the groundwater velocity must be known. A total of 127 TCE plumes were considered across 24 DOE sites. The four sites retained for the assessment were: (1) Brookhaven National Laboratory, OU III; (2) Paducah Gaseous Diffusion Plant, Northwest Plume; (3) Rocky Flats Environmental Technology Site, Industrialized Area--Southwest Plume and 903 Pad South Plume; and (4) Savannah River Site, A/M Area Plume. For each of these sites, a co-contaminant derived from the same source area as TCE was used as a nonbiodegrading tracer. The tracer determined the extent to which concentration decreases in the plume can be accounted for solely by abiotic processes such as dispersion and dilution. Any concentration decreases not accounted for by these processes must be explained by some other natural attenuation mechanism. Thus, ''half-lives'' presented herein are in addition to attenuation that occurs due to hydrologic mechanisms. This ''tracer-corrected method'' has previously been used at the DOE's Idaho National Engineering and Environmental Laboratory in conjunction with other techniques to document the occurrence of intrinsic aerobic cometabolism. Application of this method to other DOE sites is the first step to determining whether this might be a significant natural attenuation mechanism on a broader scale. Application of the tracer-corrected method to data from the Brookhaven

  12. Plasma-parameter measurements using neutral-particle-beam attenuation

    International Nuclear Information System (INIS)

    Foote, J.H.; Molvik, A.W.; Turner, W.C.

    1982-01-01

    Intense and energetic neutral-particle-beam injection used for fueling or heating magnetically confined, controlled-fusion experimental plasmas can also provide diagnostic measurements of the plasmas. The attenuation of an atomic beam (mainly from charge-exchange and ionization interactions) when passing through a plasma gives the plasma line density. Orthogonal arrays of highly collimated detectors of the secondary-electron-emission type have been used in magnetic-mirror experiments to measure neutral-beam attenuation along chords through the plasma volume at different radial and axial positions. The radial array is used to infer the radial plasma-density profile; the axial array, to infer the axial plasma-density profile and the ion angular distribution at the plasma midplane

  13. A novel live-attenuated vaccine candidate for mayaro Fever.

    Directory of Open Access Journals (Sweden)

    William J Weise

    2014-08-01

    Full Text Available Mayaro virus (MAYV is an emerging, mosquito-borne alphavirus that causes a dengue-like illness in many regions of South America, and which has the potential to urbanize. Because no specific treatment or vaccine is available for MAYV infection, we capitalized on an IRES-based approach to develop a live-attenuated MAYV vaccine candidate. Testing in infant, immunocompetent as well as interferon receptor-deficient mice demonstrated a high degree of attenuation, strong induction of neutralizing antibodies, and efficacy against lethal challenge. This vaccine strain was also unable to infect mosquito cells, a major safety feature for a live vaccine derived from a mosquito-borne virus. Further preclinical development of this vaccine candidate is warranted to protect against this important emerging disease.

  14. Attenuation correction factors for cylindrical, disc and box geometry

    International Nuclear Information System (INIS)

    Agarwal, Chhavi; Poi, Sanhita; Mhatre, Amol; Goswami, A.; Gathibandhe, M.

    2009-01-01

    In the present study, attenuation correction factors have been experimentally determined for samples having cylindrical, disc and box geometry and compared with the attenuation correction factors calculated by Hybrid Monte Carlo (HMC) method [ C. Agarwal, S. Poi, A. Goswami, M. Gathibandhe, R.A. Agrawal, Nucl. Instr. and. Meth. A 597 (2008) 198] and with the near-field and far-field formulations available in literature. It has been observed that the near-field formulae, although said to be applicable at close sample-detector geometry, does not work at very close sample-detector configuration. The advantage of the HMC method is that it is found to be valid for all sample-detector geometries.

  15. Sustainability of natural attenuation of nitrate in agricultural aquifers

    Science.gov (United States)

    Green, Christopher T.; Bekins, Barbara A.

    2010-01-01

    Increased concentrations of nitrate in groundwater in agricultural areas, coinciding with increased use of chemical and organic fertilizers, have raised concern because of risks to environmental and human health. At some sites, these problems are mitigated by natural attenuation of nitrate as a result of microbially mediated reactions. Results from U.S. Geological Survey (USGS) research under the National Water-Quality Assessment (NAWQA) program show that reactions of dissolved nitrate with solid aquifer minerals and organic carbon help lower nitrate concentrations in groundwater beneath agricultural fields. However, increased fluxes of nitrate cause ongoing depletion of the finite pool of solid reactants. Consumption of the solid reactants diminishes the capacity of the aquifer to remove nitrate, calling into question the long-term sustainability of these natural attenuation processes.

  16. Attenuation of Vibrio fischeri quorum sensing using rationally designed polymers.

    Science.gov (United States)

    Piletska, Elena V; Stavroulakis, Georgios; Karim, Kal; Whitcombe, Michael J; Chianella, Iva; Sharma, Anant; Eboigbodin, Kevin E; Robinson, Gary K; Piletsky, Sergey A

    2010-04-12

    A first attempt to attenuate the quorum sensing (QS) of a marine heterotroph microorganism, Vibrio fischeri , using signal molecule-sequestering polymers (SSPs) is presented. A set of rationally designed polymers with affinity toward a signal molecule of V. fischeri , N-(beta-ketocaproyl)-l-homoserine lactone (3-oxo-C6-AHL) was produced. It is reported that computationally designed polymers could sequester a signal molecule of V. fischeri and prevent QS-controlled phenotypes (in this case, bioluminescence) from being up-regulated. It was proven that the attenuation of bioluminescence of V. fischeri was due to sequestration of the signal molecule by specific polymers and not due to the toxicity of polymer or nonspecific depletion of nutrients. The ability to disrupt the bacterial communication using easy to synthesize and chemically inert polymers could provide a new concept for the development of pharmaceuticals and susceptible device coatings such as catheters.

  17. Signal Attenuation Curve for Different Surface Detector Arrays

    Science.gov (United States)

    Vicha, J.; Travnicek, P.; Nosek, D.; Ebr, J.

    2014-06-01

    Modern cosmic ray experiments consisting of large array of particle detectors measure the signals of electromagnetic or muon components or their combination. The correction for an amount of atmosphere passed is applied to the surface detector signal before its conversion to the shower energy. Either Monte Carlo based approach assuming certain composition of primaries or indirect estimation using real data and assuming isotropy of arrival directions can be used. Toy surface arrays of different sensitivities to electromagnetic and muon components are assumed in MC simulations to study effects imposed on attenuation curves for varying composition or possible high energy anisotropy. The possible sensitivity of the attenuation curve to the mass composition is also tested for different array types focusing on a future apparatus that can separate muon and electromagnetic component signals.

  18. Anatomy of the TAMA SAS seismic attenuation system

    International Nuclear Information System (INIS)

    Marka, Szabolcs; Takamori, Akiteru; Ando, Masaki; Bertolini, Alessandro; Cella, Giancarlo; DeSalvo, Riccardo; Fukushima, Mitsuhiro; Iida, Yukiyoshi; Jacquier, Florian; Kawamura, Seiji; Nishi, Yuhiko; Numata, Kenji; Sannibale, Virginio; Somiya, Kentaro; Takahashi, Ryutaro; Tariq, Hareem; Tsubono, Kimio; Ugas, Jose; Viboud, Nicolas; Wang Chenyang; Yamamoto, Hiroaki; Yoda, Tatsuo

    2002-01-01

    The TAMA SAS seismic attenuation system was developed to provide the extremely high level of seismic isolation required by the next generation of interferometric gravitational wave detectors to achieve the desired sensitivity at low frequencies. Our aim was to provide good performance at frequencies above ∼10 Hz, while utilizing only passive subsystems in the sensitive frequency band of the TAMA interferometric gravitational wave detectors. The only active feedback is relegated below 6 Hz and it is used to damp the rigid body resonances of the attenuation chain. Simulations, based on subsystem performance characterizations, indicate that the system can achieve rms mirror residual motion measured in a few tens of nanometres. We will give a brief overview of the subsystems and point out some of the characterization results, supporting our claims of achieved performance. SAS is a passive, UHV compatible and low cost system. It is likely that extremely sensitive experiments in other fields will also profit from our study

  19. The UV attenuation in JWST target VV 191

    Science.gov (United States)

    Holwerda, Benne

    2017-08-01

    We aim to map the UV-near-IR attenuation curve along many sightlines within nearby disk galaxies to resolve a large fundamental uncertainty in galaxy evolution studies: the variance in the attenuation curve within an indivual galaxy disk on linear scales relatively blue elliptical beautifully backlights the outer disk of a foreground face-on spiral galaxy.Dither strategy:We opt for a 2-point dither in the case of the F336W observations (1 orbit) and a 3pt dither strategy for the F225W observations. The 9 orbits for the F225W observations are broken into three groupings of 3 orbits in the 3 dither pattern. This is to ensure correction of cosmics and detector artifacts. Our secondary aim is an HST/JWST image with good public outreach potential and our aim is to maximize image quality for this reason as well.

  20. Is Necessary Attenuation Correction for Cat Brain PET?

    International Nuclear Information System (INIS)

    Kim, Jin Su; Lee, Jae Sung; Park, Min Hyun; Im, Ki Chun; Oh, Seung Ha; Lee, Dong Soo; Moon, Dae Hyuk

    2007-01-01

    Photon attenuation and scatter corrections (AC and SC) were necessary for quantification of human PET. However, there is no consensus on whether AC and SC are necessary for the cat brain PET imaging. Since post-injection transmission (TX) PET scans are not permitted or provided to microPET scanner users at present, additional time for performing TX scan and awaiting FDG uptake is required for attenuation and scatter corrections. Increasing probability of subject movement and possible biological effect of long term anesthesia would be the problem in additional TX scan. The aim of this study was to examine the effect of AC and SC for the quantification of cat brain PET data