Incommensurability Effects in Odd Length J_1-J_2 Quantum Spin Chains: On-site magnetization and Entanglement

For the antiferromagnetic J_1-J_2 quantum spin chain with an even number of sites, the point J_2^d=1/2 J_1 is a disorder point. It marks the onset of incommensurate real space correlations for J_2>J_2^d. At a distinct larger value of J_2^L=0.52036(6)J_1, the Lifshitz point, the peak in the static structure factor begins to move away from k=\pi. Here, we focus on chains with an odd number of sites. In this case the disorder point is also at J_2^d=1/2 J_1, but the behavior close to the Lifshitz point, J_2^L approx. 0.538 J_1, is quite different: starting at J_2^L, the ground-state goes through a sequence of level crossings as its momentum changes away from k=\pi/2. An even length chain, on the other hand, is gapped for any J_2>0.24J_1 and has the ground-state momentum k=0. This gradual change in the ground-state wave function for chains with an odd number of sites is reflected in a dramatic manner directly in the ground-state on-site magnetization as well as in the bi-partite von Neumann entanglement entropy. Our results are based on DMRG calculations and variational calculations performed in a restricted Hilbert space defined in the valence bond picture. In the vicinity of the point J_2=1/2 J_1, we expect the variational results to be very precise.Comment: Accepted for publication in Phys. Rev.

The influence of environment in the development of later adolescents

This item was digitized by the Internet Archive. Thesis (M.A.)--Boston Universit

Single aggressive interactions increase urinary glucocorticoid levels in wild male chimpanzees

Financial support was provided by British Academy [http://www.britac.ac.uk/] (CC), Leakey Foundation [http://www.leakeyfoundation.org/] (CC, RMW, TD), Leverhulm Trust [http://www.leverhulme.ac.uk/] (KZ), Max Planck Society [http://www.eva.mpg.de/] (AW, CC, RMW, TD) and the Royal Zoological Society of Scotland [http://www.rzss.org.uk/], in providing core funding for Budongo Conservation Field Station. This project has received additional funding from the European Union’s Seventh Framework Program for research, technological development and demonstration [http://ec.europa.eu/research/fp7/index_e​n.cfm] under grant agreement no 283871.A basic premise in behavioural ecology is the cost-benefit arithmetic, which determines both behavioural decisions and evolutionary processes. Aggressive interactions can be costly on an energetic level, demanding increased energy or causing injuries, and on a psychological level, in the form of increased anxiety and damaged relationships between opponents. Here we used urinary glucocorticoid (uGC) levels to assess the costs of aggression in wild chimpanzees of Budongo Forest, Uganda. We collected 169 urine samples from nine adult male chimpanzees following 14 aggressive interactions (test condition) and 10 resting events (control condition). Subjects showed significantly higher uGC levels after single aggressive interactions compared to control conditions, likely for aggressors as well as victims. Higher ranking males had greater increases of uGC levels after aggression than lower ranking males. In contrast, uGC levels showed no significant change in relation to aggression length or intensity, indicating that psychological factors might have played a larger role than mere energetic expenditure. We concluded that aggressive behaviour is costly for both aggressors and victims and that costs seem poorly explained by energetic demands of the interaction. Our findings are relevant for studies of post-conflict interactions, since we provide evidence that both aggressors and victims experience a stress response to conflict.Publisher PDFPeer reviewe

Alexander Stephan: Christa Wolf

München: C.H. Beck, 1976. (Autorenbücher, 4), 143 p

Lithographic patterning of polymeric media for biotechnology applications

Lithographic patterning has heavily utilized in the semiconductor industry for its ability to pattern vast numbers of complex shapes down to the nanometer scale. However, only recently has this technology been employed in the biotechnology field despite the fact that most of that the most important biological components such as cells, antibodies, DNA and proteins operate at this level. This work is an exploration of the use of lithographic printing methods in two areas deeply-entrenched in biotechnology: self assembly and microarray-based manipulation of biological media. It was inspired by the natural self assembly which occurs in nature and in our bodies at all scales. The majority of this work dealt with the patterning of bioreactive copolymers into different three-dimensional microshapes which could be functionalized with single strands of DNA for subsequent sequence-specific particle assembly. This type of technology, where very small-scale matter can be directed to self assembly into programmed macrostructures in a highly-specific manner has the capability to be adapted for many next-generation applications in drug delivery, nanofabrication, biosensing, and microelectronics. A secondary technology was explored in this work involving the paired sequencing of antibody gene sequences with the aid of lithographically-patterned microarrays. This methodology represents a bridging of bottom-up fabrication methods of DNA and proteins with top-down optical fabrication techniques which is already finding increasing utility in applications such as vaccine discovery, diagnostics, and autoimmune research. Because of the versatile nature of the components of this research, it is the hope of the author that the techniques discovered and explored here provide support and inspiration for future research in the biotechnology field as well as in other fields which may benefit as well.Chemical Engineerin

The association of periodontal diseases with metabolic syndrome and obesity

Periodontitis is a multifactorial chronic inflammatory disease associated with dysbiotic plaque biofilms and characterized by progressive destruction of the tooth‐supporting apparatus. Globally, it is estimated that 740 million people are affected by its severe form. Periodontitis has been suggested to be linked to obesity and metabolic syndrome. Obesity, defined as excessive fat accumulation, is a complex multifactorial chronic inflammatory disease, with a high and increasing prevalence. Metabolic syndrome is defined as a cluster of obesity, dyslipidemia, hypertension, and dysglycemia. Obesity, metabolic syndrome and periodontitis are among the most common non‐communicable diseases and a large body of evidence from epidemiologic studies supports the association between these conditions. Extensive research has established plausible mechanisms to explain how these conditions can negatively impact each other, pointing to a bidirectional adverse relationship. At present there is only limited evidence available from a few intervention studies. Nevertheless, the global burden of periodontitis combined with the obesity epidemic has important clinical and public health implications for the dental team. In accordance with the common risk factor approach for tackling non‐communicable diseases, it has been proposed that oral healthcare professionals have an important role in the promotion of periodontal health and general well‐being through facilitation of healthy lifestyle behaviours

Copulation Calls in Female Chimpanzees ( Pan troglodytes schweinfurthii ) Convey Identity but Do Not Accurately Reflect Fertility

Copulation calls are a relatively common feature of female primate behavior thought to function in the advertisement of female receptivity and subsequent incitation of male-male competition. To date, the majority of work on copulation calling behavior has focused on various monkey species, with little empirical evidence from the great apes. Previous research on wild chimpanzees (Pan troglodytes schweinfurthii) has suggested that estrous females produce copulation calls to avoid monopolization by single males and to minimize competition from other females. We here extended these findings by investigating to what degree these social demands were reflected in the calls' acoustic structure. We recorded and acoustically analyzed 71 copulation call bouts from 6 adult female chimpanzees in the Budongo Forest, Uganda. We did not find any acoustic differences in calls given by females in fertile and nonfertile periods, as assessed by their hormonal profiles. However, the calls' acoustic structure did reliably encode identity cues of the calling female. We propose that, in chimpanzees, the use and morphology of copulation calls have jointly been shaped by the selective advantage of concealing fertility. Owing to the low visibility conditions associated with chimpanzees' natural forest habitat and their dispersed social system, providing identity cues may be of particular biological relevance for these nonhuman primate

Abatacept in difficult-to-treat juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is the most common chronic rheumatic disease in children and an important cause of short-term and long-term disability. Gene changes in the immune system can predispose to JIA and regulation of the immune system is crucial in the pathogenesis. The goal of therapy is complete disease control using disease-modifying antirheumatic drugs (DMARDS). Activated T-cells may play a role in the immunopathology of JIA. Therefore, targeting T-cell activation is a rational approach for the treatment of JIA. Abatacept (ABA), a selective co-stimulation modulator, has been shown to be effective in treating all JIA subtypes and is generally safe and well tolerated in JIA. Neutralizing antibodies were found in 6/9 (67%) of seropositive patients, but anti-ABA antibodies did not appear to be associated with disease flare, serious adverse events, acute infusional adverse events, hypersensitivity, autoimmune disorders, or low ABA serum concentrations. Anti-ABA antibodies were more frequent when ABA concentrations were below therapeutic levels. Although information on ABA in JIA is still limited, available data suggest a potential role in difficult to treat JIA patients previously treated with other biologic agents and for non-responders to TNF-blockade