941 research outputs found
Nuclear shadowing in deep inelastic scattering on nuclei: leading twist versus eikonal approaches
We use several diverse parameterizations of diffractive parton distributions,
extracted in leading twist QCD analyses of the HERA diffractive deep inelastic
scattering (DIS) data, to make predictions for leading twist nuclear shadowing
of nuclear quark and gluon distributions in DIS on nuclei. We find that the
HERA diffractive data are sufficiently precise to allow us to predict large
nuclear shadowing for gluons and quarks, unambiguously. We performed detailed
studies of nuclear shadowing for up and charm sea quarks and gluons within
several scenarios of shadowing and diffractive slopes, as well as at central
impact parameters. We compare these leading twist results with those obtained
from the eikonal approach to nuclear shadowing (which is based on a very
different space-time picture) and observe sharply contrasting predictions for
the size and Q^2-dependence of nuclear shadowing. The most striking differences
arise for the interaction of small dipoles with nuclei, in particular for the
longitudinal structure function F_{L}^{A}.Comment: 43 pages, 16 figures, requires JHEP style fil
Multiple antimicrobial resistance in plague: An emerging public health risk
Antimicrobial resistance in Yersinia pestis is rare, yet constitutes a significant international public health and biodefense threat. In 1995, the first multidrug resistant (MDR) isolate of Y. pestis (strain IP275) was identified, and was shown to contain a self-transmissible plasmid (pIP1202) that conferred resistance to many of the antimicrobials recommended for plague treatment and prophylaxis. Comparative analysis of the DNA sequence of Y. pestis plasmid pIP1202 revealed a near identical IncA/C plasmid backbone that is shared by MDR plasmids isolated from Salmonella enterica serotype Newport SL254 and the fish pathogen Yersinia ruckeri YR71. The high degree of sequence identity and gene synteny between the plasmid backbones suggests recent acquisition of these plasmids from a common ancestor. In addition, the Y. pestis pIP1202-like plasmid backbone was detected in numerous MDR enterobacterial pathogens isolated from retail meat samples collected between 2002 and 2005 in the United States. Plasmid-positive strains were isolated from beef, chicken, turkey and pork, and were found in samples from the following states: California, Colorado, Connecticut, Georgia, Maryland, Minnesota, New Mexico, New York and Oregon. Our studies reveal that this common plasmid backbone is broadly disseminated among MDR zoonotic pathogens associated with agriculture. This reservoir of mobile resistance determinants has the potential to disseminate to Y. pestis and other human and zoonotic bacterial pathogens and therefore represents a significant public health concern
Recurrent mutation of IGF signalling genes and distinct patterns of genomic rearrangement in osteosarcoma
Osteosarcoma is a primary malignancy of bone that affects children and adults. Here, we present the largest sequencing study of osteosarcoma to date, comprising 112 childhood and adult tumours encompassing all major histological subtypes. A key finding of our study is the identification of mutations in insulin-like growth factor (IGF) signalling genes in 8/112 (7%) of cases. We validate this observation using fluorescence in situ hybridization (FISH) in an additional 87 osteosarcomas, with IGF1 receptor (IGF1R) amplification observed in 14% of tumours. These findings may inform patient selection in future trials of IGF1R inhibitors in osteosarcoma. Analysing patterns of mutation, we identify distinct rearrangement profiles including a process characterized by chromothripsis and amplification. This process operates recurrently at discrete genomic regions and generates driver mutations. It may represent an age-independent mutational mechanism that contributes to the development of osteosarcoma in children and adults alike
Association of Accelerometry-Measured Physical Activity and Cardiovascular Events in Mobility-Limited Older Adults: The LIFE (Lifestyle Interventions and Independence for Elders) Study.
BACKGROUND:Data are sparse regarding the value of physical activity (PA) surveillance among older adults-particularly among those with mobility limitations. The objective of this study was to examine longitudinal associations between objectively measured daily PA and the incidence of cardiovascular events among older adults in the LIFE (Lifestyle Interventions and Independence for Elders) study. METHODS AND RESULTS:Cardiovascular events were adjudicated based on medical records review, and cardiovascular risk factors were controlled for in the analysis. Home-based activity data were collected by hip-worn accelerometers at baseline and at 6, 12, and 24 months postrandomization to either a physical activity or health education intervention. LIFE study participants (n=1590; age 78.9Ā±5.2 [SD] years; 67.2% women) at baseline had an 11% lower incidence of experiencing a subsequent cardiovascular event per 500 steps taken per day based on activity data (hazard ratio, 0.89; 95% confidence interval, 0.84-0.96; P=0.001). At baseline, every 30 minutes spent performing activities ā„500 counts per minute (hazard ratio, 0.75; confidence interval, 0.65-0.89 [P=0.001]) were also associated with a lower incidence of cardiovascular events. Throughout follow-up (6, 12, and 24 months), both the number of steps per day (per 500 steps; hazard ratio, 0.90, confidence interval, 0.85-0.96 [P=0.001]) and duration of activity ā„500 counts per minute (per 30 minutes; hazard ratio, 0.76; confidence interval, 0.63-0.90 [P=0.002]) were significantly associated with lower cardiovascular event rates. CONCLUSIONS:Objective measurements of physical activity via accelerometry were associated with cardiovascular events among older adults with limited mobility (summary score >10 on the Short Physical Performance Battery) both using baseline and longitudinal data. CLINICAL TRIAL REGISTRATION:URL: http://www.clinicaltrials.gov. Unique identifier: NCT01072500
Large-amplitude driving of a superconducting artificial atom: Interferometry, cooling, and amplitude spectroscopy
Superconducting persistent-current qubits are quantum-coherent artificial
atoms with multiple, tunable energy levels. In the presence of large-amplitude
harmonic excitation, the qubit state can be driven through one or more of the
constituent energy-level avoided crossings. The resulting
Landau-Zener-Stueckelberg (LZS) transitions mediate a rich array of
quantum-coherent phenomena. We review here three experimental works based on
LZS transitions: Mach-Zehnder-type interferometry between repeated LZS
transitions, microwave-induced cooling, and amplitude spectroscopy. These
experiments exhibit a remarkable agreement with theory, and are extensible to
other solid-state and atomic qubit modalities. We anticipate they will find
application to qubit state-preparation and control methods for quantum
information science and technology.Comment: 13 pages, 5 figure
Evaluating the effects of six alcohol-related message frames on emotions and intentions: The neglected role of disgust
A total of 120 18- to 56-year-olds, divided into six groups containing equal numbers of men and women, were shown a textual message and associated photograph featuring alcohol-related behaviour. Subsequently, questions were answered about intentions to reduce consumption, to drink moderately and how positive and negative the messages made participants feel. Loss-framed messages, in particular those featuring health-related disgust, were the most effective for increasing intentions to reduce alcohol intake. In conclusion, studies have over-focused on fear-loss frames, neglecting the utility of disgust-loss frames in health messages. This study suggests that disgust-loss frames deserve equivalent attention
Tissue Glucocorticoid Metabolism in Adrenal Insufficiency:A Prospective Study of Dual-release Hydrocortisone Therapy
Background: Patients with adrenal insufficiency (AI) require life-long glucocorticoid (GC) replacement therapy. Within tissues, cortisol (F) availability is under the control of the isozymes of 11Ī²-hydroxysteroid dehydrogenase (11Ī²-HSD). We hypothesize that corticosteroid metabolism is altered in patients with AI because of the nonphysiological pattern of current immediate release hydrocortisone (IR-HC) replacement therapy. The use of a once-daily dual-release hydrocortisone (DR-HC) preparation, (PlenadrenĀ®), offers a more physiological cortisol profile and may alter corticosteroid metabolism in vivo.Study Design and Methods: Prospective crossover study assessing the impact of 12 weeks of DR-HC on systemic GC metabolism (urinary steroid metabolome profiling), cortisol activation in the liver (cortisone acetate challenge test), and subcutaneous adipose tissue (microdialysis, biopsy for gene expression analysis) in 51 patients with AI (primary and secondary) in comparison to IR-HC treatment and age- and BMI-matched controls.Results: Patients with AI receiving IR-HC had a higher median 24-hour urinary excretion of cortisol compared with healthy controls (72.1 Āµg/24 hours [IQR 43.6-124.2] vs 51.9 Āµg/24 hours [35.5-72.3], P = .02), with lower global activity of 11Ī²-HSD2 and higher 5-alpha reductase activity. Following the switch from IR-HC to DR-HC therapy, there was a significant reduction in urinary cortisol and total GC metabolite excretion, which was most significant in the evening. There was an increase in 11Ī²-HSD2 activity. Hepatic 11Ī²-HSD1 activity was not significantly altered after switching to DR-HC, but there was a significant reduction in the expression and activity of 11Ī²-HSD1 in subcutaneous adipose tissue.Conclusion: Using comprehensive in vivo techniques, we have demonstrated abnormalities in corticosteroid metabolism in patients with primary and secondary AI receiving IR-HC. This dysregulation of pre-receptor glucocorticoid metabolism results in enhanced glucocorticoid activation in adipose tissue, which was ameliorated by treatment with DR-HC
Metagenome sequence analysis of filamentous microbial communities obtained from geochemically distinct geothermal channels reveals specialization of three aquificales lineages.
The Aquificales are thermophilic microorganisms that inhabit hydrothermal systems worldwide and are considered one of the earliest lineages of the domain Bacteria. We analyzed metagenome sequence obtained from six thermal āfilamentous streamerā communities (~40 Mbp per site), which targeted three different groups of Aquificales found in Yellowstone National Park (YNP). Unassembled metagenome sequence and PCR-amplified 16S rRNA gene libraries revealed that acidic, sulfidic sites were dominated by Hydrogenobaculum (Aquificaceae) populations, whereas the circumneutral pH (6.5 - 7.8) sites containing dissolved sulfide were dominated by Sulfurihydrogenibium spp. (Hydrogenothermaceae). Thermocrinis (Aquificaceae) populations were found primarily in the circumneutral sites with undetectable sulfide, and to a lesser extent in one sulfidic system at pH 8. Phylogenetic analysis of assembled sequence containing 16S rRNA genes as well as conserved protein-encoding genes revealed that the composition and function of these communities varied across geochemical conditions. Each Aquificales lineage contained genes for CO2 fixation by the reverse TCA cycle, but only the Sulfurihydrogenibium populations perform citrate cleavage using ATP citrate lyase (Acl). The Aquificaceae populations use an alternative pathway catalyzed by two separate enzymes, citryl CoA synthetase (Ccs) and citryl CoA lyase (Ccl). All three Aquificales lineages contained evidence of aerobic respiration, albeit due to completely different types of heme Cu oxidases (subunit I) involved in oxygen reduction. The distribution of Aquificales populations and differences among functional genes involved in energy generation and electron transport is consistent with the hypothesis that geochemical parameters (e.g., pH, sulfide, H2, O2) have resulted in niche specialization among members of the Aquificales
The role of steroids in the management of brain metastases: a systematic review and evidence-based clinical practice guideline
Do steroids improve neurologic symptoms in patients with metastatic brain tumors compared to no treatment? If steroids are given, what dose should be used? Comparisons include: (1) steroid therapy versus none. (2) comparison of different doses of steroid therapy.
Target population
These recommendations apply to adults diagnosed with brain metastases.
Recommendations
Steroid therapy versus no steroid therapy
Asymptomatic brain metastases patients without mass effect
Insufficient evidence exists to make a treatment recommendation for this clinical scenario.
Brain metastases patients with mild symptoms related to mass effect
Level 3 Corticosteroids are recommended to provide temporary symptomatic relief of symptoms related to increased intracranial pressure and edema secondary to brain metastases. It is recommended for patients who are symptomatic from metastatic disease to the brain that a starting dose of 4ā8Ā mg/day of dexamethasone be considered.
Brain metastases patients with moderate to severe symptoms related to mass effect
Level 3 Corticosteroids are recommended to provide temporary symptomatic relief of symptoms related to increased intracranial pressure and edema secondary to brain metastases. If patients exhibit severe symptoms consistent with increased intracranial pressure, it is recommended that higher doses such as 16Ā mg/day or more be considered.
Choice of Steroid
Level 3 If corticosteroids are given, dexamethasone is the best drug choice given the available evidence.
Duration of Corticosteroid Administration
Level 3 Corticosteroids, if given, should be tapered slowly over a 2Ā week time period, or longer in symptomatic patients, based upon an individualized treatment regimen and a full understanding of the long-term sequelae of corticosteroid therapy.
Given the very limited number of studies (two) which met the eligibility criteria for the systematic review, these are the only recommendations that can be offered based on this methodology. Please see āDiscussionā and āSummaryā section for additional details
Regional Business Cycles in New Zealand: Do they exist? What Might Drive Them?
We use National Bank of New Zealand Regional Economic Activity data, to identify and characterise classical business cycle turning points, for New Zealandās 14 regions and aggregate New Zealand activity. Using Concordance statistic measures, logistic model and GMM estimation methods, meaningful regional business cycles have been identified and a number of significant associations established. All regions exhibit cyclical asymmetry for both durations and amplitudes, and synchronisations between aggregate NZ activity and each region are contemporaneous. The regional cycles rarely die of old age but are terminated by particular events. The regions most highly synchronised with the NZ activity cycle are Auckland, Canterbury, and Nelson-Marlborough; those least so are Gisborne and Southland. Noticeably strong co-movements are evident for certain regions. Geographical proximity matters, and unusually dry conditions can be associated with cyclical downturns in certain regions. There is no discernable evidence of association with net immigration movements, and no significant evidence of regional cycle movements being associated with real house price cycles. The agriculture-based nature of the New Zealand economy is highlighted by the strong influence of external economic shocks on rural economic performance. In particular, there is considerable evidence of certain regional cycles being associated with movements in New Zealandās aggregate terms of trade, real prices of milksolids, real dairy land prices and total rural land prices. JEL Classification: C22, E32, R11, R12, R15 Keywords: Classical business cycle; Turning Points; Regional business cycles; Concordance statistics; New Zealan
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