5,657 research outputs found
The quasi-molecular stage of ternary fission
We developed a three-center phenomenological model,able to explain qualitatively the recently obtained experimental results concerning the quasimolecular stage of a light-particle accompanied fission process. It was derived from the liquid drop model under the assumption that the aligned configuration, with the emitted particle between the light and heavy fragment, is reached by increasing continuously the separation distance, while the radii of the heavy fragment and of the light particle are kept constant. In such a way,a new minimum of a short-lived molecular state appears in the deformation energy at a separation distance very close to the touching point. This minimum allows the existence of a short-lived quasi-molecular state, decaying into the three final fragments.The influence of the shell effects is discussed. The half-lives of some quasimolecular states which could be formed in the Be and C accompanied fission of Cf are roughly estimated to be the order of 1 ns, and 1 ms, respectively
The Effects of Incubation Length and Temperature on the Specificity and Sensitivity of the BANA (N‐Benzoyl‐DL‐Arginine‐Naphthylamide) Test
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141244/1/jper0848.pd
Liana diversity, abundance, and mortality in a tropical wet forest in Costa Rica
Lianas can have a large impact on the diversity, structure, and dynamics of tropical forests, yet they remain essentially unknown even in some of the most intensely studied tropical forests, such as La Selva Biological Station in Costa Rica. We quantified the diversity, abundance, and mortality of lianas in primary and selectively logged forest at La Selva for over 3 years, from January 1999 until July 2002. We measured, identified, permanently marked, and mapped all lianas ≥1.3 m in length and 2 mm in diameter, whether climbing or free-standing, in nine, m (864 m2) plots. There were no significant differences in density, diversity, or mortality between primary forest and areas that were selectively logged approximately 50 years prior to our study. We found a mean density of 1493 lianas ha−1 and a mean species richness of 23 species per 864 m2 plot. Annual mortality was 9.4% over all size-classes, but was the highest for the smallest individuals (\u3c2 cm in diameter). Annual mortality for larger individuals (≥5 cm) was much lower over the 3.5-year period (3.2% per year) and the five most abundant species suffered no mortality in this size-class. In contrast to many lowland neotropical forests, where Bignoniaceae and Fabaceae are reported to be the dominant liana families, at La Selva we found that Sapindaceae was the most speciose family and Dilleniaceae the most abundant. Moutabea aculeata (Polygalaceae) was the most abundant species, constituting approximately 17% of the individuals and having the lowest mortality of all 60 species. The 10 most abundant species at La Selva accounted for more than 60% of all individuals. Compared to other lowland sites in the neotropics, including other wet forests, the abundance and diversity of lianas at La Selva are very low
FREE WILL, DETERMINISM, LIBERTARIANISM AND AUSTRIAN ECONOMICS
В тази статия се изразява твърдението, че позицията на свободната воля е правилна, а тази на детерминизма е неправилна, и че либертарианството и австрийската икономика са съвместими с първо споменатата, но не и с последната позиция. This paper makes the claim that the free will position is correct, that of determinism incorrect, and that libertarianism and Austrian economics are compatible with the former but not the latter
Is There a Metabolic Program in the Skeletal Muscle of Obese Individuals?
Severe obesity (BMI ≥ 40 kg/m2) is associated with multiple defects in skeletal muscle which contribute to insulin resistance and a reduction in fatty acid oxidation (FAO) in this tissue. These metabolic derangements are retained in human skeletal muscle cells raised in culture. Together, these findings are indicative of a dysfunctional global metabolic program with severe obesity which is of an epigenetic or genetic origin. Weight loss via gastric bypass surgery can “turn off” and/or correct components of this metabolic program as insulin sensitivity is restored; however, the impairment in FAO in skeletal muscle remains evident. Physical activity can improve FAO and insulin action, indicating that this patient population is not exercise resistant and that exercise offers a pathway to circumvent the abnormal program. Findings presented in this review will hopefully increase the understanding of and aid in preventing and/or treating the severely obese condition
Multi-wavelength observations of the peculiar red giant HR 3126
Ultraviolet observations of the red giant HR 3126 are combined with multi-wavelength data in order to provide a firmer basis for explaining the arc-minute sized nebula surrounding the object. Possibilities as to the location of HR 3126 on the Hertzsprung-Russel diagram, and to the formation mechanisms of the reflection nebula IC 2220 associated with it, are summarized
Impact of HIV/AIDS on care and outcomes of severe sepsis
INTRODUCTION: There has been dramatic improvement in survival for patients with HIV/AIDS; however, some studies on patients with HIV/AIDS and serious illness have reported continued low rates of intensive care. The purpose of this study was to examine patterns of care and outcomes for patients with severe sepsis and HIV/AIDS and compare them with those of patients with severe sepsis without HIV/AIDS. METHODS: We assessed data from all 1999 discharge abstracts from all non-federal hospitals in six US states. Patient demographic characteristics, discharge diagnoses, resource use, and outcomes were extracted. Analyses were performed using chi-square, Wilcoxon rank sum, or regression techniques, as appropriate. RESULTS: We identified 74,020 patients with severe sepsis (7,638 (10.3%) had HIV/AIDS) using ICD-9-CM codes. Patients with severe sepsis and HIV/AIDS had a similar mean length of stay (16.9 days versus 17.7 days; p = 0.0669), had lower mean hospitalization cost (30,537; p < 0.0001), were less likely to be admitted to the intensive care unit (37% versus 56%; p < 0.0001), and had a greater mortality (29% versus 20%; p < 0.0001) than those without HIV/AIDS. After adjustment for cohort differences, patients with severe sepsis and HIV/AIDS had increased likelihood of death (OR (95% CI) = 2.41 (2.23–2.61)) and were substantially less likely to be admitted to the intensive care unit (OR (95% CI) = 0.54 (0.51–0.59)). When compared with those with severe sepsis and HIV/AIDS, patients with severe sepsis without HIV/AIDS were universally more likely to be admitted to the intensive care unit, even when they had comorbid illnesses with equal or worse expected in-hospital mortality (e.g., metastatic cancer). CONCLUSION: For patients with severe sepsis, there are differences in care and outcomes for those with HIV/AIDS. Further research is needed to examine the delivery of care for patients with severe sepsis and HIV/AIDS
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Nanomolar-potency 'co-potentiator' therapy for cystic fibrosis caused by a defined subset of minimal function CFTR mutants.
Available CFTR modulators provide no therapeutic benefit for cystic fibrosis (CF) caused by many loss-of-function mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel, including N1303K. We previously introduced the concept of 'co-potentiators' (combination-potentiators) to rescue CFTR function in some minimal function CFTR mutants. Herein, a screen of ~120,000 drug-like synthetic small molecules identified active co-potentiators of pyrazoloquinoline, piperidine-pyridoindole, tetrahydroquinoline and phenylazepine classes, with EC50 down to ~300 nM following initial structure-activity studies. Increased CFTR chloride conductance by up to 8-fold was observed when a co-potentiator (termed 'Class II potentiator') was used with a classical potentiator ('Class I potentiator') such as VX-770 or GLPG1837. To investigate the range of CFTR mutations benefitted by co-potentiators, 14 CF-associated CFTR mutations were studied in transfected cell models. Co-potentiator efficacy was found for CFTR missense, deletion and nonsense mutations in nucleotide binding domain-2 (NBD2), including W1282X, N1303K, c.3700A > G and Q1313X (with corrector for some mutations). In contrast, CFTR mutations G85E, R334W, R347P, V520F, R560T, A561E, M1101K and R1162X showed no co-potentiator activity, even with corrector. Co-potentiator efficacy was confirmed in primary human bronchial epithelial cell cultures generated from a N1303K homozygous CF subject. The Class II potentiators identified here may have clinical benefit for CF caused by mutations in the NBD2 domain of CFTR
Thermal Analysis and Testing of Candidate Materials for PAIDAE Inflatable Aeroshell
The Program to Advance Inflatable-Decelerators for Atmospheric Entry (PAIDAE) is a NASA project tasked with developing and evaluating viable inflatable-decelerator aeroshell geometries and materials. Thermal analysis of material layups supporting an inflatable aeroshell was completed in order to identify expected material response, failure times, and to establish an experimental test matrix to keep barrier layer materials from reaching critical temperature limits during thermal soak. Material layups were then tested in the 8- foot High Temperature Tunnel (8'HTT), where they were subjected to hypersonic aerothermal heating conditions, similar to those expected for a Mars entry. This paper presents a broad overview of the thermal analysis supporting multiple materials, and layup configurations tested in the 8'HTT at flight conditions similar to those that would be experienced during Mars entry trajectories. Direct comparison of TPS samples tested in the 8'HTT verify that the thermal model accurately predicted temperature profiles when there are up to four materials in the test layup. As the number of material layers in each test layup increase (greater than 4), the accuracy of the prediction decreases significantly. The inaccuracy of the model predictions for layups with more than four material layers is believed to be a result of the contact resistance values used throughout the model being inaccurate. In addition, the harsh environment of the 8'HTT, including hot gas penetrating through the material layers, could also be a contributing factor
Lensed Quasar Hosts
Gravitational lensing assists in the detection of quasar hosts by amplifying
and distorting the host light away from the unresolved quasar core images. We
present the results of HST observations of 30 quasar hosts at redshifts 1 < z <
4.5. The hosts are small in size (r_e <~ 6 kpc), and span a range of
morphologies consistent with early-types (though smaller in mass) to
disky/late-type. The ratio of the black hole mass (MBH, from the virial
technique) to the bulge mass (M_bulge, from the stellar luminosity) at 1<z<1.7
is broadly consistent with the local value; while MBH/M_bulge at z>1.7 is a
factor of 3--6 higher than the local value. But, depending on the stellar
content the ratio may decline at z>4 (if E/S0-like), flatten off to 6--10 times
the local value (if Sbc-like), or continue to rise (if Im-like). We infer that
galaxy bulge masses must have grown by a factor of 3--6 over the redshift range
3>z>1, and then changed little since z~1. This suggests that the peak epoch of
galaxy formation for massive galaxies is above z~1. We also estimate the duty
cycle of luminous AGNs at z>1 to be ~1%, or 10^7 yrs, with sizable scatter.Comment: 8 pages, 6 figures, review article with C. Impey at the conference on
"QSO Host Galaxies: Evolution and Environment", Aug. 29-Sep. 2, 2005, Lorentz
Center, Leiden, The Netherland
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