6,953 research outputs found
Broad distribution effects in sums of lognormal random variables
The lognormal distribution describing, e.g., exponentials of Gaussian random
variables is one of the most common statistical distributions in physics. It
can exhibit features of broad distributions that imply qualitative departure
from the usual statistical scaling associated to narrow distributions.
Approximate formulae are derived for the typical sums of lognormal random
variables. The validity of these formulae is numerically checked and the
physical consequences, e.g., for the current flowing through small tunnel
junctions, are pointed out.Comment: 14 pages, 9 figures. Minor changes + Gini coefficient and 4 refs.
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Using Standardized Student Evaluation Instruments To Measure Teaching Effectiveness In Lecture/Recitation Mode Classes
This paper investigates the variability of student teaching effectiveness survey evaluations among the various recitation sections when lecture/recitation instruction is utilized with the same instructor both delivering the lecture and teaching all of the corresponding recitation sections. The research results indicate that when an instructor teaches multiple sections using lecture/recitation instruction, then the meaningful measure of the instructor’s teaching is the average of the student ratings for the various recitation sections. This study focuses on the variability of the students’ responses to each item in the survey instrument as measured by its standard deviation
Properties of Intra-group Stars and Galaxies in Galaxy Groups: "Normal" versus "Fossil" Groups
Cosmological LCDM simulations of 12 M_vir~10^14 Msun galaxy groups have been
performed, invoking star formation, chemical evolution with non-instantaneous
recycling, metallicity dependent radiative cooling, strong star-burst driven
galactic super-winds and effects of a meta-galactic UV field. At z=0,
intra-group light (IGL) fractions are found to be 12-45%. Low values refer to
groups with only a small difference between the R-band magnitudes of the first
and second ranked group galaxy, large are typical of "fossil" groups (FGs). The
IG stars in the 4 FGs are 0.3-0.5 Gyr older than in the 8 nonFGs. For the IGL,
B-R=~1.4, in good agreement with observations. For FGs/nonFGs the iron
abundance of the IG stars is slightly sub-solar in the central parts (r~100
kpc) decreasing to about 40% solar at about 0.5 r_vir The IG stars are
alpha-element enhanced with [O/Fe] increasing with r, and an overall
[O/Fe]~0.45, indicating predominant SNII enrichment. The velocity distributions
of the IG stars and group galaxies are, at r>~30 kpc, significantly more
radially anisotropic for FGs than for nonFGs. So a characteristic of FG
formation, apart from formation time (D'Onghia et al.), may be the "initial"
velocity distribution of the group galaxies. For FGs one can dynamically infer
the (dark matter dominated) mass distribution of the groups all the way to
r_vir, from the kinematics of the IG stars or group galaxies. For the nonFGs
this method overestimates the group mass at r>~200 kpc, by up to a factor of
two at r_vir. This is interpreted as FGs being, in general, more relaxed than
nonFGs. Finally, FGs of the above M_vir should host ~500 planetary nebulae at
projected distances between 100 and 1000 kpc from the first ranked galaxy. All
results appear consistent with the FG formation scenario of D'Onghia et al.Comment: 12 pages, 15 figures, Accepted for MNRAS, Printing in colour
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Genetic polymorphism, medical therapy and sequential cardiac function in patients with heart failure
FUNDAMENTO: Variantes funcionais do gene da enzima conversora da angiotensina (ECA) podem estar associados com a resposta à terapia em portadores de insuficiência cardÃaca (IC). OBJETIVO: Testar a hipótese de diferenças na avaliação ecocardiográfica seqüencial da fração de ejeção do ventrÃculo esquerdo de pacientes com IC em tratamento farmacológico, inclusive com inibidores da ECA, em relação ao polimorfismo de inserção (I) e deleção (D) do gene da ECA. MÉTODOS: Estudamos 168 pacientes (média de idade 43,3±10,1 anos), 128 (76,2%) dos quais homens, com IC e ecocardiogramas seqüenciais. O polimorfismo I/D foi determinado por reação em cadeia da polimerase. A fração de ejeção do ventrÃculo esquerdo (FEVE) foi analisada comparativamente aos genótipos. Mais de 90% dos pacientes estavam tomando inibidores da ECA. RESULTADOS: Houve um aumento significantemente maior na FEVE média em pacientes com o alelo D, em comparação com pacientes com genótipo II (p = 0,01) após um seguimento médio de 38,9 meses. O alelo D foi associado com aumento de 8,8% na FEVE média no mesmo perÃodo. Além disso, observou-se uma tendência para um efeito do "número de cópias" do alelo D sobre o aumento da FEVE média com o tempo: uma diferença de 3,5% na variação da FEVE entre os pacientes com genótipos II e ID (p = 0,03) e de 5% entre os pacientes com genótipos II e DD (p = 0,02). CONCLUSÃO: O polimorfismo de deleção do gene da ECA pode estar associado com a resposta ao tratamento farmacológico com inibidores da ECA em portadores de IC. Outros estudos controlados poderão contribuir para uma melhor compreensão das influências genéticas sobre a resposta à terapia.BACKGROUND: Functional variants of angiotensin-converting enzyme (ACE) gene may be associated with response to therapy in patients with heart failure (HF). OBJECTIVE: To test the hypothesis of differences in sequential echocardiographic evaluations of left ventricular ejection fraction in patients with HF on medical therapy, including ACE inhibitors in relation to insertion (I) / deletion (D) polymorphism of the ACE gene. METHODS: We studied 168 patients (mean age 43.3±10.1 years), 128 (76.2%) men, with HF and sequential echocardiograms. The I/D polymorphism was determined by polymerase chain reaction. Left ventricular ejection fraction (LVEF) was analyzed comparatively to genotypes. More than 90% of patients were on ACE inhibitors. RESULTS: There was a significantly greater increase in mean LVEF in patients with the D allele compared to patients with the II genotype (p=0.01) after a mean follow-up of 38.9 months. The D allele was associated with an increase of 8.8% in mean LVEF over the same period. Furthermore, there was a tendency toward a D allele "copy number" effect on the increase of mean LVEF over time: a 3.5% difference in LVEF variation between patients with the II and the ID genotypes (p = 0.03) and a 5% difference between patients with the II and DD genotypes (p=0.02). CONCLUSION: ACE gene deletion polymorphism may be operative in response to medical treatment that included ACE inhibitors in patients with HF. Further controlled studies may contribute to better understanding of genetic influences on response to therapy
Large phenotype jumps in biomolecular evolution
By defining the phenotype of a biopolymer by its active three-dimensional
shape, and its genotype by its primary sequence, we propose a model that
predicts and characterizes the statistical distribution of a population of
biopolymers with a specific phenotype, that originated from a given genotypic
sequence by a single mutational event. Depending on the ratio g0 that
characterizes the spread of potential energies of the mutated population with
respect to temperature, three different statistical regimes have been
identified. We suggest that biopolymers found in nature are in a critical
regime with g0 in the range 1-6, corresponding to a broad, but not too broad,
phenotypic distribution resembling a truncated Levy flight. Thus the biopolymer
phenotype can be considerably modified in just a few mutations. The proposed
model is in good agreement with the experimental distribution of activities
determined for a population of single mutants of a group I ribozyme.Comment: to appear in Phys. Rev. E; 7 pages, 6 figures; longer discussion in
VII, new fig.
Acute Myeloid Leukemia t(8;21) after treatment for hyperthyroidism using radioactive iodine: Secondary Leukemia?
Acute leukemia following treatment with Iodine131 is a rare event. The possible carcinogenic effect of Iodine131 is still not clear and a large series of cases did not show an increased incidence of cancer. A case of AML t(8;21), three years after Iodine131 treatment for hyperthyroidism, is reported. Secondary AML with t(8;21) is described following exposure to drugs that target topoisomerase II and radiotherapy. The controversial potential of Iodine131 as a leukemogenic agent and the fact that t(8;21) is also found in de-novo AML, emphasize the problem in establishing a relationship between these events although this potential can not be ruled out.Universidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina (EPM)UNIFESP, EPMSciEL
Residence Time (RT), a new parameter to predict neurosteroidogenic efficacy of Translocator Protein (TSPO) ligands: N,N-dialkyl-2-arylindol-3-ylglyoxylamides, a case study
Targeting neuroactive steroid biosynthetic pathway by specific 18 kDa Translocator Protein (TSPO) ligands may represent a therapeutic approach in a variety of neurodegenerative and neuropsychiatric diseases. However, the lack of correlation between the binding affinity and the in vitro steroidogenic efficacy has limited the identification of lead compounds by a traditional affinity-based drug discovery strategy. Our recent researches indicate that the key factor for robust steroidogenic TSPO ligand efficacy is not the binding affinity per se, but rather the time the compound spends into the target, namely its Residence Time (RT). The assessment of this kinetic parameter during the in vitro characterization of compounds appears mandatory in order to obtain structure-efficacy relationships suitable for the future development of novel molecules with promising pharmacological properties
First evidence of resistance to pyrethroid insecticides in Italian Aedes albopictus populations after 26 years since invasion
Aedes albopictus has spread during the last decades all over the world. This has increased significantly the risk of exotic arbovirus transmission (e.g. Chikungunya, Dengue, and Zika) also in temperate areas, as testified by the Chikungunya 2007- and 2017-outbreaks in north-east and central Italy. Insecticides represent a main tool for limiting the circulation of these mosquito-borne viruses. The aim of the present study is to start filling the current gap of knowledge on pyrethroid insecticide resistance of European Ae. albopictus populations focusing on populations from Italy, Albania and Greece
Tanbih: Get To Know What You Are Reading
We introduce Tanbih, a news aggregator with intelligent analysis tools to
help readers understanding what's behind a news story. Our system displays news
grouped into events and generates media profiles that show the general
factuality of reporting, the degree of propagandistic content,
hyper-partisanship, leading political ideology, general frame of reporting, and
stance with respect to various claims and topics of a news outlet. In addition,
we automatically analyse each article to detect whether it is propagandistic
and to determine its stance with respect to a number of controversial topics
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