793 research outputs found
Scale Dependence of the Retarded van der Waals Potential
We study the ground state energy for a system of two hydrogen atoms coupled
to the quantized Maxwell field in the limit together with the
relative distance between the atoms increasing as , . In particular we determine explicitly the crossover function from the
van der Waals potential to the retarded van der Waals
potential, which takes place at scale .Comment: 19 page
Regional Development: An Econometric Study of the Role of Water Development in Effectuating Population and Income Changes
Twelve measures of regional economic growth, including populations and three measures of income were compared for areas with and without water investment in 246 counties and 42 water resources subareas in the states of Utah, Colorado, New Mexico, Montana, Wyoming, Idaho, and Nevada. Simple mean omparisons for these measures compiled for the decades of 1940-1950, 1950-1960, and 1960-1970 failed to support the hypothesis that economic growth of those counties and subareas receiving water investment was significantly highter than in those areas which did not, with the possible exception of the 1940-1950 decade. This result is obciously tempered by the fact that with-without comparisons taken on a cross-sectional basis may be inaccurage to the extent that spatial units used in the analysis are not homogenous in all respects but the presence or absence of water investment. Population, farm income, median family income, and per acre agricultural land values as measures of economic growth were regressed on various classes of water investment (Total, M&1, Recreation, and Irrigation investment, and other related variables) for the spatial units. Results obtained from this analysis were inconclusive with respect to the hypothesized role of water investment in effectuating economic growth. For small areas in New Mexico where more detailed records of water investment were available, a nine equation econometric model was estimated using a three-stage least squares analysis. As specified, this model facilitated an examination of the interactive effect of water development as a causal variable and as an endogenous variable which responds to other growth inducements. Test statistics for multi-equation systems are only indicative, and the statistical results were nonconclusive, although expected signs on the coefficients were obtained in most instances. Input-output and economic base-models were used to examine two case studies of water investment in Western Coloado. The objective was to demonstrate the methodology and the magnitudes of change in regional economic activity (gross regional output, exports, income, and employment) which could be associated with major irrigation-type water developments. In this analysis it was found that total gross output attributable to the projects ranged from zero in the petroleum and mining sectors to a high of 260,302 in the dairy industry. Multiplicative effects on employment income and gross economic activity ranged from 1.06 to 2.30 times their initial magnitude. Income and employment multipliers were of similar magnitude. it should be recognized that these estimates cannot e viewed in the same manner as similar growth increments at the national level, as would typically be done, because of the strong possibility of regional offsets occurring in other regions not participating in water development. To the extent that growth in other areas is reduced by the growth of a particular region, these reductions should be subtracted from the growth measured in the latter set of regions. In all tests conducted no conclusive evidence was found taht water development causes regions to grow faster than those regions which did not receive water investment. This is not to say that growth in those regions receiving water investment was not higher than it would have been had the investment not been made. However, it does provide evidence that, an average among the regions included within this analysis, that those areas which did not receive major water investments grow at a faster rate than those which did. Thus, the input-output approach shows potential inpacts from water investment in a general equilibrium context, but rest son the assumption that other concurrent events which could produce similar or offsetting effects in the region are held constant. The cross-section analysis measures total changes in a regional economy overtime, but the multiplicity of events, other than water investment, may obscure the effects of water investment
Validation of Aura Microwave Limb Sounder OH measurements with Fourier Transform Ultra-Violet Spectrometer total OH column measurements at Table Mountain, California
Dihydrolipoic acid reduces cytochrome b561 proteins.
Cytochrome b561 (Cyt-b561) proteins constitute a family of trans-membrane proteins that are present in a wide variety of organisms. Two of their characteristic properties are the reducibility by ascorbate (ASC) and the presence of two distinct b-type hemes localized on two opposite sides of the membrane. Here we show that the tonoplast-localized and the putative tumor suppressor Cyt-b561 proteins can be reduced by other reductants than ASC and dithionite. A detailed spectral analysis of the ASC-dependent and dihydrolipoic acid (DHLA)-dependent reduction of these two Cyt-b561 proteins is also presented. Our results are discussed in relation to the known antioxidant capability of DHLA as well as its role in the regeneration of other antioxidant compounds of cells. These results allow us to speculate on new biological functions for the trans-membrane Cyt-b561 proteins
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Bridging the age gap: observational cohort study of effects of chemotherapy and trastuzumab on recurrence, survival and quality of life in older women with early breast cancer
Background: Chemotherapy improves outcomes for high risk early breast cancer (EBC) patients but is infrequently offered to older individuals. This study determined if there are fit older patients with high-risk disease who may benefit from chemotherapy.
Methods: A multicentre, prospective, observational study was performed to determine chemotherapy (±trastuzumab) usage and survival and quality-of-life outcomes in EBC patients aged ≥70 years. Propensity score-matching adjusted for variation in baseline age, fitness and tumour stage.
Results: Three thousands four hundred sixteen women were recruited from 56 UK centres between 2013 and 2018. Two thousands eight hundred eleven (82%) had surgery. 1520/2811 (54%) had high-risk EBC and 2059/2811 (73%) were fit. Chemotherapy was given to 306/1100 (27.8%) fit patients with high-risk EBC. Unmatched comparison of chemotherapy versus no chemotherapy demonstrated reduced metastatic recurrence risk in high-risk patients(hazard ratio [HR] 0.36 [95% CI 0.19–0.68]) and in 541 age, stage and fitness-matched patients(adjusted HR 0.43 [95% CI 0.20–0.92]) but no benefit to overall survival (OS) or breast cancer-specific survival (BCSS) in either group. Chemotherapy improved survival in women with oestrogen receptor (ER)-negative cancer (OS: HR 0.20 [95% CI 0.08–0.49];BCSS: HR 0.12 [95% CI 0.03–0.44]).Transient negative quality-of-life impacts were observed.
Conclusions: Chemotherapy was associated with reduced risk of metastatic recurrence, but survival benefits were only seen in patients with ER-negative cancer. Quality-of-life impacts were significant but transient. Trial Registration: ISRCTN 46099296
A Genome-Scale Metabolic Reconstruction of Mycoplasma genitalium, iPS189
With a genome size of ∼580 kb and approximately 480 protein coding regions, Mycoplasma genitalium is one of the smallest known self-replicating organisms and, additionally, has extremely fastidious nutrient requirements. The reduced genomic content of M. genitalium has led researchers to suggest that the molecular assembly contained in this organism may be a close approximation to the minimal set of genes required for bacterial growth. Here, we introduce a systematic approach for the construction and curation of a genome-scale in silico metabolic model for M. genitalium. Key challenges included estimation of biomass composition, handling of enzymes with broad specificities, and the lack of a defined medium. Computational tools were subsequently employed to identify and resolve connectivity gaps in the model as well as growth prediction inconsistencies with gene essentiality experimental data. The curated model, M. genitalium iPS189 (262 reactions, 274 metabolites), is 87% accurate in recapitulating in vivo gene essentiality results for M. genitalium. Approaches and tools described herein provide a roadmap for the automated construction of in silico metabolic models of other organisms
Empirical Legal Studies Before 1940: A Bibliographic Essay
The modern empirical legal studies movement has well-known antecedents in the law and society and law and economics traditions of the latter half of the 20th century. Less well known is the body of empirical research on legal phenomena from the period prior to World War II. This paper is an extensive bibliographic essay that surveys the English language empirical legal research from approximately 1940 and earlier. The essay is arranged around the themes in the research: criminal justice, civil justice (general studies of civil litigation, auto accident litigation and compensation, divorce, small claims, jurisdiction and procedure, civil juries), debt and bankruptcy, banking, appellate courts, legal needs, legal profession (including legal education), and judicial staffing and selection. Accompanying the essay is an extensive bibliography of research articles, books, and reports
Process evaluation of the Bridging the Age Gap in Breast Cancer decision support intervention cluster randomised trial
Background
The Bridging the Age Gap in Breast Cancer research programme sought to improve treatment decision-making for older women with breast cancer by developing and testing, in a cluster randomised trial (n = 1339 patients), two decision support interventions (DESIs). Both DESIs were used in the intervention arm and each comprised an online risk prediction model, brief decision aid and information booklet. One DESI supported the decision to have either primary endocrine therapy (PET) or surgery with adjuvant therapies and the second supported the decision to have adjuvant chemotherapy after surgery or not.
Methods
Sixteen sites were randomly selected to take part in the process evaluation. Multiple methods of data collection were used. Medical Research Council (MRC) guidelines for the evaluation of complex interventions were used.
Results
Eighty-two patients, mean age 75.5 (range 70–93), provided data for the process evaluation. Seventy-three interviews were completed with patients. Ten clinicians from six intervention sites took part in telephone interviews. Dose: Ninety-one members of staff in the intervention arm received intervention training. Reach: The online tool was accessed on 324 occasions by 27 clinicians. Reasons for non-use of the online tool were commonly that the patient had already made a decision or that there was no online access in the clinic. Of the 32 women for whom there were data available, fifteen from the intervention arm and six from the usual care arm were offered a choice of treatment. Fidelity: Clinicians used the online tool in different ways, with some using it during the consultation and others checking the online survival estimates before the consultation. Adaptation: There was evidence of adaptation when using the DESIs. A lack of infrastructure, e.g. internet access, was a barrier to the use of the online tool. The brief decision aid was rarely used. Mediators: Shared decision-making: Most patients felt able to contribute to decision-making and expressed high levels of satisfaction with the process. Participants’ responses to intervention: Six patients reported the DESIs to be very useful, one somewhat useful and two moderately useful.
Conclusions
Clinicians who participated were mainly supportive of the interventions and had attempted some adaptations to make the interventions applicable, but there were practical and engagement barriers that led to sub-optimal adoption in routine practice
Persistent Gastric Colonization with Burkholderia pseudomallei and Dissemination from the Gastrointestinal Tract following Mucosal Inoculation of Mice
Melioidosis is a disease of humans caused by opportunistic infection with the soil and water bacterium Burkholderia pseudomallei. Melioidosis can manifest as an acute, overwhelming infection or as a chronic, recurrent infection. At present, it is not clear where B. pseudomallei resides in the mammalian host during the chronic, recurrent phase of infection. To address this question, we developed a mouse low-dose mucosal challenge model of chronic B. pseudomallei infection and investigated sites of bacterial persistence over 60 days. Sensitive culture techniques and selective media were used to quantitate bacterial burden in major organs, including the gastrointestinal (GI) tract. We found that the GI tract was the primary site of bacterial persistence during the chronic infection phase, and was the only site from which the organism could be consistently cultured during a 60-day infection period. The organism could be repeatedly recovered from all levels of the GI tract, and chronic infection was accompanied by sustained low-level fecal shedding. The stomach was identified as the primary site of GI colonization as determined by fluorescent in situ hybridization. Organisms in the stomach were associated with the gastric mucosal surface, and the propensity to colonize the gastric mucosa was observed with 4 different B. pseudomallei isolates. In contrast, B. pseudomallei organisms were present at low numbers within luminal contents in the small and large intestine and cecum relative to the stomach. Notably, inflammatory lesions were not detected in any GI tissue examined in chronically-infected mice. Only low-dose oral or intranasal inoculation led to GI colonization and development of chronic infection of the spleen and liver. Thus, we concluded that in a mouse model of melioidosis B. pseudomallei preferentially colonizes the stomach following oral inoculation, and that the chronically colonized GI tract likely serves as a reservoir for dissemination of infection to extra-intestinal sites
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