167 research outputs found
Theoretical Basis for Controlling Minimal Tumor Temperature During Interstitial Conductive Heat Therapy
This paper describes simulation of steady-state intratumoral temperatures achieved by a simple modality of local heat therapy: interstitial treatment with parallel arrays of warmed, conductive heating elements. During “conductive heating” power is directly deposited only in the interstitial probes. Adjacent tissue is warmed by heat conduction. Simulations of interstitial conductive heating involved solution of the bioheat transfer equation on a digital computer using a finite difference model of the treated tissue. The simulations suggest that when the complete temperature distributions for conductive interstitial hyperthermia are examined in detail, substantial uniformity of the temperature distributions is evident. Except for a thin sleeve of tissue surrounding each heating element, a broad, flat central valley of temperature elevation is achieved, with a well defined minimum temperature, very close to modal and median tissue temperatures. Because probes are inserted directly in tumor tissue, the thin sleeve of overheated tissue would not be expected to cause normal tissue complications. The temperature of the heated probes must be continuously controlled and increased in the face of increased blood flow in order to maintain minimum tumor temperature. However, correction for changes in blood flow is possible by adjusting probe temperature according to a feedback control scheme, in which power dissipation from each probe is the sensed input variable. Conductive interstitial heating with continually controlled probe temperature deserves investigation as a technique for local hyperthermia therapy
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A system simulation to enhance stockpile stewardship (ASSESS)
This paper describes the ASSESS project, whose goal is to construct a policy driven enterprise simulation of the DOE nuclear weapons complex (DOE/NWC). ASSESS encompasses the full range of stockpile stewardship activities by incorporating simulation component models that are developed and managed by local experts. ASSESS runs on a heterogeneous distributed computing environment and implements multi-layered user access capabilities. ASSESS allows the user to create hypothetical policies governing stockpile stewardship, simulate the resulting operation of the DOE/NWC, and analyze the relative impact of each policy
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Quantify uncertain emergency search techniques (QUEST) -- Theory and user`s guide
As recent world events show, criminal and terrorist access to nuclear materials is a growing national concern. The national laboratories are taking the lead in developing technologies to counter these potential threats to the national security. Sandia National laboratories, with support from Pacific Northwest National Laboratory and the Bechtel Nevada, Remote Sensing Laboratory, has developed QUEST (a model to Quantify Uncertain Emergency Search Techniques), to enhance the performance of organizations in the search for lost or stolen nuclear material. In addition, QUEST supports a wide range of other applications, such as environmental monitoring, nuclear facilities inspections, and searcher training. QUEST simulates the search for nuclear materials and calculates detector response for various source types and locations. The probability of detecting a radioactive source during a search is a function of many different variables, including source type, search location and structure geometry (including shielding), search dynamics (path and speed), and detector type and size. Through calculation of dynamic detector response, QUEST makes possible quantitative comparisons of various sensor technologies and search patterns. The QUEST model can be used as a tool to examine the impact of new detector technologies, explore alternative search concepts, and provide interactive search/inspector training
QKD with finite resources: secret key rates via R\'enyi entropies
A realistic Quantum Key Distribution (QKD) protocol necessarily deals with
finite resources, such as the number of signals exchanged by the two parties.
We derive a bound on the secret key rate which is expressed as an optimization
problem over R\'enyi entropies. Under the assumption of collective attacks by
an eavesdropper, a computable estimate of our bound for the six-state protocol
is provided. This bound leads to improved key rates in comparison to previous
results.Comment: 11 pages, 2 figure
The Amazon Epiphyte Network: A First Glimpse Into Continental-Scale Patterns of Amazonian Vascular Epiphyte Assemblages
Epiphytes are still an understudied plant group in Amazonia. The aim of this study was to identify distributional patterns and conservation priorities for vascular epiphyte assemblages (VEA) across Amazonia. We compiled the largest Amazonian epiphyte plot database to date, through a multinational collaborative effort of 22 researchers and 32 field sites located across four Amazonian countries – the Amazonian Epiphyte Network (AEN). We addressed the following continental-scale questions by utilizing the AEN database comprising 96,448 epiphyte individuals, belonging to 518 vascular taxa, and growing on 10,907 tree individuals (phorophytes). Our objectives here are, first, to present a qualitative evaluation of the geographic distribution of the study sites and highlight regional lacunae as priorities for future quantitative inventories. Second, to present the floristic patterns for Amazonia-wide VEA and third, to combine multivariate analyses and rank abundance curves, controlled by major Amazonian habitat types, to determine how VEA vary geographically and ecologically based on major Amazonian habitat types. Three of the most striking patterns found are that: (1) VEA are spatially structured as floristic similarity decays with geographic distance; (2) a core group of 22 oligarchic taxa account for more than a half of all individuals; and (3) extensive floristic sampling gaps still exist, mainly across the highly threatened southern Amazonian deforestation belt. This work represents a first step toward unveiling distributional pattern of Amazonian VEA, which is important to guide future questions on ecology and species distribution ranges of VEA once the collaborative database grows allowing a clearer view of patterns
Moderate energy restriction with high protein diet results in healthier outcome in women
BACKGROUND:
The present study compares two different weight reduction regimens both with a moderately high protein intake on body composition, serum hormone concentration and strength performance in non-competitive female athletes.
METHODS:
Fifteen normal weighted women involved in recreational resistance training and aerobic training were recruited for the study (age 28.5 ± 6.3 yr, height 167.0 ± 7.0 cm, body mass 66.3 ± 4.2 kg, body mass index 23.8 ± 1.8, mean ± SD). They were randomized into two groups. The 1 KG group (n = 8; energy deficit 1100 kcal/day) was supervised to reduce body weight by 1 kg per week and the 0.5 KG group (n = 7; energy deficit 550 kcal/day) by 0.5 kg per week, respectively. In both groups protein intake was kept at least 1.4 g/kg body weight/day and the weight reduction lasted four weeks. At the beginning of the study the energy need was calculated using food and training diaries. The same measurements were done before and after the 4-week weight reduction period including total body composition (DXA), serum hormone concentrations, jumping ability and strength measurements
RESULTS:
During the 4-week weight reduction period there were no changes in lean body mass and bone mass, but total body mass, fat mass and fat percentage decreased significantly in both groups. The changes were greater in the 1 KG group than in the 0.5 KG group in total body mass (p < 0.001), fat mass (p < 0.001) and fat percentage (p < 0.01). Serum testosterone concentration decreased significantly from 1.8 ± 1.0 to 1.4 ± 0.9 nmol/l (p < 0.01) in 1 KG and the change was greater in 1 KG (30%, p < 0.001) than in 0.5 KG (3%). On the other hand, SHBG increased significantly in 1 KG from 63.4 ± 17.7 to 82.4 ± 33.0 nmol/l (p < 0.05) during the weight reducing regimen. After the 4-week period there were no changes in strength performance in 0.5 KG group, however in 1 KG maximal strength in bench press decreased (p < 0.05) while endurance strength in squat and counter movement jump improved (p < 0.05)
CONCLUSION:
It is concluded that a weight reduction by 0.5 kg per week with ~1.4 g protein/kg body weight/day can be recommended to normal weighted, physically active women instead of a larger (e.g. 1 kg per week) weight reduction because the latter may lead to a catabolic state. Vertical jumping performance is improved when fat mass and body weight decrease. Thus a moderate weight reduction prior to a major event could be considered beneficial for normal built athletes in jumping events.peerReviewe
Metabolic responses to the acute ingestion of two commercially available carbonated beverages: A pilot study
<p>Abstract</p> <p>Background</p> <p>The purpose of this placebo-controlled, double-blind cross-over study was to compare the effects of two commercially available soft drinks on metabolic rate.</p> <p>Methods</p> <p>After giving informed consent, twenty healthy men and women were randomly assigned to ingest 12 ounces of Celsius™ and, on a separate day, 12 ounces of Diet Coke®. All subjects completed both trials using a randomized, counterbalanced design. Metabolic rate (via indirect calorimetry) and substrate oxidation (via respiratory exchange ratio) were measured at baseline (pre-ingestion) and at the end of each hour for 3 hours post-ingestion.</p> <p>Results</p> <p>Two-way ANOVA revealed a significant interaction (p < 0.001) between trials in metabolic rate. Scheffe post-hoc testing indicated that metabolic rate increased by 13.8% (+ 0.6 L/min, p < 0.001) 1 hr post, 14.4% (+0.63 L/min, p < 0.001) 2 hr post, and 8.5% (+0.37 L/min, p < 0.004) 3 hr post Celsius™ ingestion. In contrast, small (~4–6%) but statistically insignificant increases in metabolic rate were noted following Diet Coke<sup>® </sup>ingestion. No differences in respiratory exchange ratio were noted between trials.</p> <p>Conclusion</p> <p>These preliminary findings indicate Celsius™ has thermogenic properties when ingested acutely. The effects of repeated, chronic ingestion of Celsius™ on body composition are unknown at this time.</p
Early childhood education and care as a space for social support in urban contexts of diversity
The Happiest Kids on Earth : Gender Equality and Adolescent Life Satisfaction in Europe and North America
Cross-national differences in adolescent life satisfaction in Europe and North America are consistent, but remain poorly understood. While previous studies have predominantly focused on the explanatory role of economic factors, such as national wealth and income equality, they revealed weak associations, at most. This study examines whether societal gender equality can explain the observed cross-national variability in adolescent life satisfaction. Based on the assumption that gender equality fosters a supportive social context, for example within families through a more equal involvement of fathers and mothers in child care tasks, adolescent life satisfaction was expected to be higher in more gender-equal countries. To test this hypothesis, national-level data of gender equality (i.e., women’s share in political participation, decision making power, economic participation and command over resources) were linked to data from 175,470 adolescents aged 11–16 years old (Mage = 13.6, SD = 1.64, 52% girls) from 34 European and North American countries involved in the 2009/10 Health Behaviour in School-aged Children (HBSC) study. Results of linear multilevel regression analyses indicate that adolescents in countries with relatively high levels of gender equality report higher life satisfaction than their peers in countries with lower levels of gender equality. The association between gender equality and adolescent life satisfaction remained significant after controlling for national wealth and income equality. It was equally strong for boys and girls. Moreover, the association between gender equality and life satisfaction was explained by social support in the family, peer and school context. This analysis suggests that gender equality fosters social support among members of a society, which in turn contributes to adolescent life satisfaction. Thus, promoting gender equality is likely to benefit all members of a society; not just by giving equal rights to women and girls, but also by fostering a supportive social climate for all
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