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Search Results: 1 - 10 of 5720 matches for " Emma Cohen "
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On the Widom-Rowlinson Occupancy Fraction in Regular Graphs
Emma Cohen,Will Perkins,Prasad Tetali
Mathematics , 2015,
Abstract: We consider the Widom-Rowlinson model of two types of interacting particles on d-regular graphs. We prove a tight upper bound on the occupancy fraction: the expected fraction of vertices occupied by a particle under a random configuration from the model. The upper bound is achieved uniquely by unions of complete graphs on d+1 vertices, $K_{d+1}$'s. As a corollary we find that $K_{d+1}$ also maximizes the normalized partition function of the Widom-Rowlinson model over the class of d-regular graphs. A special case of this shows that the normalized number of homomorphisms from any d-regular graph G to the graph $H_{WR}$, a path on three vertices with a self-loop on each vertex, is maximized by $K_{d+1}$. This proves a conjecture of Galvin.
Lattice Path Matroids: Negative Correlation and Fast Mixing
Emma Cohen,Prasad Tetali,Damir Yeliussizov
Mathematics , 2015,
Abstract: Catalan numbers arise in many enumerative contexts as the counting sequence of combinatorial structures. In this work, we consider natural Markov chains on some of the realizations of the Catalan sequence. While our main result is in deriving an $O(n^2 \log n)$ bound on the mixing time in $L_2$ (and hence total variation) distance for the random transposition chain on Dyck paths, we raise several open questions, including the optimality of the above bound. The novelty in our proof is in establishing a certain negative correlation property among random bases of lattice path matroids, including the so-called Catalan matroid which can be defined using Dyck paths.
X-ray spectral diagnostics of activity in massive stars
David H. Cohen,Emma E. Wollman,Maurice A. Leutenegger
Physics , 2010, DOI: 10.1017/S1743921311010763
Abstract: X-rays give direct evidence of instabilities, time-variable structure, and shock heating in the winds of O stars. The observed broad X-ray emission lines provide information about the kinematics of shock-heated wind plasma, enabling us to test wind-shock models. And their shapes provide information about wind absorption, and thus about the wind mass-loss rates. Mass-loss rates determined from X-ray line profiles are not sensitive to density-squared clumping effects, and indicate mass-loss rate reductions of factors of 3 to 6 over traditional diagnostics that suffer from density-squared effects. Broad-band X-ray spectral energy distributions also provide mass-loss rate information via soft X-ray absorption signatures. In some cases, the degree of wind absorption is so high that the hardening of the X-ray SED can be quite significant. We discuss these results as applied to the early O stars zeta Pup (O4 If), 9 Sgr (O4 V((f))), and HD 93129A (O2 If*).
Inverse Expander Mixing for Hypergraphs
Emma Cohen,Dhruv Mubayi,Peter Ralli,Prasad Tetali
Mathematics , 2014,
Abstract: We formulate and prove inverse mixing lemmas in the settings of simplicial complexes and k-uniform hypergraphs. In the hypergraph setting, we extend results of Bilu and Linial for graphs. In the simplicial complex setting, our results answer a question of Parzanchevski et al.
Ethics without Morality, Morality without Ethics—Politics, Identity, Responsibility in Our Contemporary World  [PDF]
Emma Palese
Open Journal of Philosophy (OJPP) , 2013, DOI: 10.4236/ojpp.2013.33055
Abstract: Ethics without morality and morality without ethics are the characteristics of two distinct eras: modernity and post-modernity. The duty to obey the law is an ethical act, but not always moral. Morality in fact is something more: a principle of responsibility and an index of humanity. This paper aims to explain the historical relationship between morality, ethics and politics up to the present day. The erosion of the nation-state, global capitalism, bio-economy leads us to rethink the meaning of ethics, morality and politics. A utilitarian ethics and a necessary morality may be the new frontiers of our contemporary world.
Effectiveness of Musculoskeletal Emergency Physiotherapy Practitioners  [PDF]
Emma Salt
Open Journal of Therapy and Rehabilitation (OJTR) , 2016, DOI: 10.4236/ojtr.2016.43013
Abstract: Relevance and Method: The purpose of this project was to evaluate the effectiveness of the Emergency Physiotherapy Practitioner (EPP) service against quality care indicators identified as part of the “gold standard” for emergency care in England. The study was prospective and evaluated time to initial assessment, total time in the emergency department and un-planned re-attendance rate within a seven-day period for all patients seen by the EPP’s over a period of one year. Outcomes: One thousand and seven patients were seen by EPPs in the emergency department. The median wait time for treatment by an EPP was 34.5 minutes (95th percentile = 122). Regional median wait time was 45 minutes (95th percentile = 138). National median wait time was 55 minutes (95th percentile = 192). Median total time spent in ED for patients seen by EPPs was 99 minutes (95th percentile = 224). Regional median total time in ED was 223 (95th percentile = 239). Nationally median total time in ED was 136 minutes (95th percentile = 336). Three percent of patients seen by an EPP returned to the ED, compared to 6% regionally and 7.5% nationally. Conclusions: EPPs excelled in all three indicators and exceeded regional and national figures. The re-return rate met the current standard of being less than 5%. It could be justified that the addition of the EPPs to the emergency department was an efficient and effective service development.
Why Are Autism Spectrum Conditions More Prevalent in Males?
Simon Baron-Cohen,Michael V. Lombardo,Bonnie Auyeung,Emma Ashwin,Bhismadev Chakrabarti,Rebecca Knickmeyer
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.1001081
Abstract: Autism Spectrum Conditions (ASC) are much more common in males, a bias that may offer clues to the etiology of this condition. Although the cause of this bias remains a mystery, we argue that it occurs because ASC is an extreme manifestation of the male brain. The extreme male brain (EMB) theory, first proposed in 1997, is an extension of the Empathizing-Systemizing (E-S) theory of typical sex differences that proposes that females on average have a stronger drive to empathize while males on average have a stronger drive to systemize. In this first major update since 2005, we describe some of the evidence relating to the EMB theory of ASC and consider how typical sex differences in brain structure may be relevant to ASC. One possible biological mechanism to account for the male bias is the effect of fetal testosterone (fT). We also consider alternative biological theories, the X and Y chromosome theories, and the reduced autosomal penetrance theory. None of these theories has yet been fully confirmed or refuted, though the weight of evidence in favor of the fT theory is growing from converging sources (longitudinal amniocentesis studies from pregnancy to age 10 years old, current hormone studies, and genetic association studies of SNPs in the sex steroid pathways). Ultimately, as these theories are not mutually exclusive and ASC is multi-factorial, they may help explain the male prevalence of ASC.
Bezielle Selectively Targets Mitochondria of Cancer Cells to Inhibit Glycolysis and OXPHOS
Vivian Chen, Richard E. Staub, Sylvia Fong, Mary Tagliaferri, Isaac Cohen, Emma Shtivelman
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0030300
Abstract: Bezielle (BZL101) is a candidate oral drug that has shown promising efficacy and excellent safety in the early phase clinical trials for advanced breast cancer. Bezielle is an aqueous extract from the herb Scutellaria barbata. We have reported previously that Bezielle was selectively cytotoxic to cancer cells while sparing non-transformed cells. In tumor, but not in non-transformed cells, Bezielle induced generation of ROS and severe DNA damage followed by hyperactivation of PARP, depletion of the cellular ATP and NAD, and inhibition of glycolysis. We show here that tumor cells' mitochondria are the primary source of reactive oxygen species induced by Bezielle. Treatment with Bezielle induces progressively higher levels of mitochondrial superoxide as well as peroxide-type ROS. Inhibition of mitochondrial respiration prevents generation of both types of ROS and protects cells from Bezielle-induced death. In addition to glycolysis, Bezielle inhibits oxidative phosphorylation in tumor cells and depletes mitochondrial reserve capacity depriving cells of the ability to produce ATP. Tumor cells lacking functional mitochondria maintain glycolytic activity in presence of Bezielle thus supporting the hypothesis that mitochondria are the primary target of Bezielle. The metabolic effects of Bezielle towards normal cells are not significant, in agreement with the low levels of oxidative damage that Bezielle inflicts on them. Bezielle is therefore a drug that selectively targets cancer cell mitochondria, and is distinguished from other such drugs by its ability to induce not only inhibition of OXPHOS but also of glycolysis. This study provides a better understanding of the mechanism of Bezielle's cytotoxicity, and the basis of its selectivity towards cancer cells.
Identification and Analysis of the Active Phytochemicals from the Anti-Cancer Botanical Extract Bezielle
Vivian Chen, Richard E. Staub, Scott Baggett, Ramesh Chimmani, Mary Tagliaferri, Isaac Cohen, Emma Shtivelman
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0030107
Abstract: Bezielle is a botanical extract that has selective anti-tumor activity, and has shown a promising efficacy in the early phases of clinical testing. Bezielle inhibits mitochondrial respiration and induces reactive oxygen species (ROS) in mitochondria of tumor cells but not in non-transformed cells. The generation of high ROS in tumor cells leads to heavy DNA damage and hyper-activation of PARP, followed by the inhibition of glycolysis. Bezielle therefore belongs to a group of drugs that target tumor cell mitochondria, but its cytotoxicity involves inhibition of both cellular energy producing pathways. We found that the cytotoxic activity of the Bezielle extract in vitro co-purified with a defined fraction containing multiple flavonoids. We have isolated several of these Bezielle flavonoids, and examined their possible roles in the selective anti-tumor cytotoxicity of Bezielle. Our results support the hypothesis that a major Scutellaria flavonoid, scutellarein, possesses many if not all of the biologically relevant properties of the total extract. Like Bezielle, scutellarein induced increasing levels of ROS of mitochondrial origin, progressive DNA damage, protein oxidation, depletion of reduced glutathione and ATP, and suppression of both OXPHOS and glycolysis. Like Bezielle, scutellarein was selectively cytotoxic towards cancer cells. Carthamidin, a flavonone found in Bezielle, also induced DNA damage and oxidative cell death. Two well known plant flavonoids, apigenin and luteolin, had limited and not selective cytotoxicity that did not depend on their pro-oxidant activities. We also provide evidence that the cytotoxicity of scutellarein was increased when other Bezielle flavonoids, not necessarily highly cytotoxic or selective on their own, were present. This indicates that the activity of total Bezielle extract might depend on a combination of several different compounds present within it.
Why Are Autism Spectrum Conditions More Prevalent in Males?
Simon Baron-Cohen ,Michael V. Lombardo,Bonnie Auyeung,Emma Ashwin,Bhismadev Chakrabarti,Rebecca Knickmeyer
PLOS Biology , 2011, DOI: 10.1371/journal.pbio.1001081
Abstract: Autism Spectrum Conditions (ASC) are much more common in males, a bias that may offer clues to the etiology of this condition. Although the cause of this bias remains a mystery, we argue that it occurs because ASC is an extreme manifestation of the male brain. The extreme male brain (EMB) theory, first proposed in 1997, is an extension of the Empathizing-Systemizing (E-S) theory of typical sex differences that proposes that females on average have a stronger drive to empathize while males on average have a stronger drive to systemize. In this first major update since 2005, we describe some of the evidence relating to the EMB theory of ASC and consider how typical sex differences in brain structure may be relevant to ASC. One possible biological mechanism to account for the male bias is the effect of fetal testosterone (fT). We also consider alternative biological theories, the X and Y chromosome theories, and the reduced autosomal penetrance theory. None of these theories has yet been fully confirmed or refuted, though the weight of evidence in favor of the fT theory is growing from converging sources (longitudinal amniocentesis studies from pregnancy to age 10 years old, current hormone studies, and genetic association studies of SNPs in the sex steroid pathways). Ultimately, as these theories are not mutually exclusive and ASC is multi-factorial, they may help explain the male prevalence of ASC.
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