Approximating the partition function of the ferromagnetic Potts model

We provide evidence that it is computationally difficult to approximate the partition function of the ferromagnetic q-state Potts model when q>2. Specifically we show that the partition function is hard for the complexity class #RHPi_1 under approximation-preserving reducibility. Thus, it is as hard to approximate the partition function as it is to find approximate solutions to a wide range of counting problems, including that of determining the number of independent sets in a bipartite graph. Our proof exploits the first order phase transition of the "random cluster" model, which is a probability distribution on graphs that is closely related to the q-state Potts model.Comment: Minor correction

Slices of the Kerr ergosurface

The intrinsic geometry of the Kerr ergosurface on constant Boyer-Lindquist (BL), Kerr, and Doran time slices is characterized. Unlike the BL slice, which had been previously studied, the other slices (i) do not have conical singularities at the poles (except the Doran slice in the extremal limit), (ii) have finite polar circumference in the extremal limit, and (iii) for sufficiently large spin parameter fail to be isometrically embeddable as a surface of revolution above some latitude. The Doran slice develops an embeddable polar cap for spin parameters greater than about 0.96.Comment: 13 pages, 6 figures; v.2: minor editing for clarification, references added, typos fixed, version published in Classical and Quantum Gravit

Irritable Bowel Syndrome patients exhibit depressive and anxiety scores in the subsyndromal range

Irritable bowel syndrome (IBS) patients frequently experience affective disorders and psychiatric outpatients frequently meet criteria for IBS. The exact nature of this co-morbidity is not clear. 34 patients with Rome-II diagnosed IBS were recruited from a Gastroenterology clinic. Patients with social anxiety disorder (10 SSRI-remitted and 7 untreated subjects) were used as a psychiatric comparison, 28 normal subjects from our register were included as a fourth group (Volunteers). Depressive and anxiety symptoms were measured by the Beck Depression Inventory (BDI) and Spielberger Trait Anxiety Inventory (STAI), respectively. Personality traits were measured with the Swedish universities Scales of Personality (SSP). IBS subjects had BDI and STAI scores intermediate between those of volunteers and patients, despite their lack of a co-morbid psychiatric diagnosis. A principle component factor analysis of the SSP dataset corresponded closely to the solution published with other samples. ANOVA revealed significant between-group differences for 7 of the 13 SSP variables

Metastatic Liposarcoma: A Cause of Symptomatic Acute Pericarditis

We describe a patient presenting with a myxoid liposarcoma of the lower thigh in whom an episode of acute pericarditis indicated the recurrence of widespread metastatic disease

Rapid Evolution of BRCA1 and BRCA2 in Humans and Other Primates

The maintenance of chromosomal integrity is an essential task of every living organism and cellular repair mechanisms exist to guard against insults to DNA. Given the importance of this process, it is expected that DNA repair proteins would be evolutionarily conserved, exhibiting very minimal sequence change over time. However, BRCA1, an essential gene involved in DNA repair, has been reported to be evolving rapidly despite the fact that many protein-altering mutations within this gene convey a significantly elevated risk for breast and ovarian cancers. Results: To obtain a deeper understanding of the evolutionary trajectory of BRCA1, we analyzed complete BRCA1 gene sequences from 23 primate species. We show that specific amino acid sites have experienced repeated selection for amino acid replacement over primate evolution. This selection has been focused specifically on humans and our closest living relatives, chimpanzees (Pan troglodytes) and bonobos (Pan paniscus). After examining BRCA1 polymorphisms in 7 bonobo, 44 chimpanzee, and 44 rhesus macaque (Macaca mulatta) individuals, we find considerable variation within each of these species and evidence for recent selection in chimpanzee populations. Finally, we also sequenced and analyzed BRCA2 from 24 primate species and find that this gene has also evolved under positive selection. Conclusions: While mutations leading to truncated forms of BRCA1 are clearly linked to cancer phenotypes in humans, there is also an underlying selective pressure in favor of amino acid-altering substitutions in this gene. A hypothesis where viruses are the drivers of this natural selection is discussed.National Institutes of Health R01-GM-093086, 8U42OD011197-13National Science Foundation BCS-07115972Burroughs Wellcome FundMolecular Bioscience

Current directions and future perspectives from the third Nematostella research conference

Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Zoology 118 (2015): 135-140, doi:10.1016/j.zool.2014.06.005.The third Nematostella vectensis Research Conference took place in December 2013 in Eilat, Israel, as a satellite to the 8th International Conference on Coelenterate Biology. The starlet sea anemone, Nematostella vectensis, has emerged as a powerful cnidarian model, in large part due to the extensive genomic and transcriptomic resources and molecular approaches that are becoming available for Nematostella, which were the focus of several presentations. In addition, research was presented highlighting the broader utility of this species for studies of development, circadian rhythms, signal transduction, and gene–environment interactions.Research in the authors’ laboratories on Nematostella is supported by National Science Foundation grants MCB-1057354 to A.M.T. and MCB-0924749 to T.D.G. Travel support for the meeting was provided to T.D.G. by Illumina, Inc. (San Diego, CA, USA), to A.M.R. by the University of North Carolina at Charlotte, and to A.M.T. by the Israel–US Binational Science Foundation (Jerusalem, Israel)

Decoherence and entanglement degradation of a qubit-qutrit system in non-inertial frames

We study the effect of decoherence on a qubit-qutrit system under the influence of global, local and multilocal decoherence in non-inertial frames. We show that the entanglement sudden death can be avoided in non-inertial frames in the presence of amplitude damping, depolarizing and phase damping channels. However, degradation of entanglement is seen due to Unruh effect. It is shown that for lower level of decoherence, the depolarizing channel degrades the entanglement more heavily as compared to the amplitude damping and phase damping channels. However, for higher values of decoherence parameters, amplitude damping channel heavily degrades the entanglement of the hybrid system. Further more, no ESD is seen for any value of Rob's acceleration.Comment: 16 pages, 5 .eps figures, 1 table; Quantum Information Processing, published online, 5 July, 201

Monitoring for Plasmodium falciparum drug resistance to artemisinin and artesunate in Binh Phuoc Province, Vietnam: 1998-2009

<p>Abstract</p> <p>Background</p> <p>Artemisinin derivatives have been used for malaria treatment in Vietnam since 1989. Reported malaria cases have decreased from 1,672,000 with 4,650 deaths in 1991, to 91,635 with 43 deaths in 2006. Current national guidelines recommend artemisinin-based combination therapy (ACT), although artesunate is still available as monotherapy through the private sector. Recent reports suggest that effectiveness of ACT and artesunate monotherapy has declined in western Cambodia. This study examined <it>Plasmodium falciparum </it>resistance patterns over 10 years in southwest Vietnam in infected patients treated with artemisinin compounds.</p> <p>Methods</p> <p>The study was conducted in two communes in Phuoc Long district, Binh Phuoc province, 100 km west of the Cambodian border. This was chosen as a likely site for emerging artemisinin resistance because of the high prevalence of <it>P. falciparum </it>malaria, and the length of time that artemisinin had been in use. In <it>vivo </it>and <it>in vitro </it>monitoring of <it>P. falciparum </it>susceptibility to anti-malarial drugs was conducted in 1998, 2001, 2004/5, and 2008/9. Patients with confirmed <it>P. falciparum </it>malaria received therapy with 5 or 7 days of artemisinin (1998 and 2001 respectively) or 7 days of artesunate</p> <p>Results</p> <p>In the four surveys, 270 patients were recruited and treated. The mean parasite clearance times differed between 1998, 2001 and 2004/5 (1.8, 2.3 and 2.1 days, P < 0.01) but not between 1998 and 2008/2009. The mean parasite clearance times were correlated with parasite density at day 0 (r = 0.4; P < 0.001). Treatment failure rates after PCR adjustment were 13.8%, 2.9%, 1.2%, and 0% respectively. Susceptibility of <it>P. falciparum </it>to artemisinin in <it>in vitro </it>tests was stable during the period, except for a rise in EC90 and EC99 in 2001.</p> <p>Conclusions</p> <p>This study showed stable levels of <it>P. falciparum </it>sensitivity to artemisinin compounds in the two sites over a ten-year period. The introduction of ACT in this area in 2003 may have protected against the development of artemisinin resistance. Adherence to the latest WHO and Vietnamese guidelines, which recommend ACT as first-line therapy in all malarious areas, and continued monitoring along the Vietnam-Cambodia border will be essential to prevent the spread of artemisinin resistance in Vietnam.</p