How Cooperative are the Dynamics in Tunneling Systems? A Computer Study for an Atomic Model Glass

Via computer simulations of the standard binary Lennard-Jones glass former we have obtained in a systematic way a large set of close-by pairs of minima on the potential energy landscape, i.e. double-well potentials (DWP). We analyze this set of DWP in two directions. At low temperatures the symmetric DWP give rise to tunneling systems. We compare the resulting low-temperature anomalies with those, predicted by the standard tunneling model. Deviations can be traced back to the energy dependence of the relevant quantities like the number of tunneling systems. Furthermore we analyze the local structure around a DWP as well as the translational pattern during the transition between both minima. Local density anomalies are crucial for the formation of a tunneling system. Two very different kinds of tunneling systems are observed, depending on the type of atom (small or large) which forms the center of the tunneling system. In the first case the tunneling system can be interpreted as a single-particle motion, in the second case it is more collective

Nonlinear Schroedinger-Poisson Theory for Quantum-Dot Helium

We use a nonlinear Schroedinger-Poisson equation to describe two interacting electrons with opposite spins confined in a parabolic potential, a quantum dot. We propose an effective form of the Poisson equation taking into account the dimensional mismatch of the two-dimensional electronic system and the three-dimensional electrostatics. The results agree with earlier numerical calculations performed in a large basis of two-body states and provide a simple model for continuous quantum-classical transition with increasing nonlinearity. Specific intriguing properties due to eigenstate non-orthogonality are emphasized.Comment: RevTeX, 8 pages with 6 included eps figure

Lexical stress information modulates the time-course of spoken-word recognition

Segmental as well as suprasegmental information is used by Dutch listeners to recognize words. The time-course of the effect of suprasegmental stress information on spoken-word recognition was investigated in a previous study, in which we tracked Dutch listeners' looks to arrays of four printed words as they listened to spoken sentences. Each target was displayed along with a competitor that did not differ segmentally in its first two syllables but differed in stress placement (e.g., 'CENtimeter' and 'sentiMENT'). The listeners' eye-movements showed that stress information is used to recognize the target before distinct segmental information is available. Here, we examine the role of durational information in this effect. Two experiments showed that initial-syllable duration, as a cue to lexical stress, is not interpreted dependent on the speaking rate of the preceding carrier sentence. This still held when other stress cues like pitch and amplitude were removed. Rather, the speaking rate of the preceding carrier affected the speed of word recognition globally, even though the rate of the target itself was not altered. Stress information modulated lexical competition, but did so independently of the rate of the preceding carrier, even if duration was the only stress cue present

Azathioprine and 6-mercaptopurine for maintenance of surgically-induced remission in Crohn’s disease

Background Crohn’s disease (CD) is a chronic relapsing inflammatory condition. Many patients fail to achieve remission with medical management and require surgical interventions. Purine analogues have been used to maintain surgically-induced remission in CD, but the effectiveness of these agents is unclear. Objectives The objectives were to evaluate the efficacy and safety of purine analogues for maintenance of surgically-induced remission in CD. Search methods We searched the following databases from inception to 30 April 2014: PubMed, MEDLINE, EMBASE, CENTRAL, and the Cochrane Inflammatory Bowel Disease and Functional Bowel Disorders Group Specialized Trials Register).We also searched the reference lists of all included studies, and contacted personal sources and drug companies to identify additional studies. The searches were not limited by language. Selection criteria Randomised controlled trials (RCTs) that compared purine analogues to placebo or another intervention, with treatment durations of at least six months were considered for inclusion. Participants were patients of any age with CD in remission following surgery. Data collection and analysis Two authors independently assessed trial eligibility and extracted data. Methodological quality was assessed using the Cochrane risk of bias tool. The primary outcome measures were clinical and endoscopic relapse as defined by the primary studies. Secondary outcomes included adverse events, withdrawal due to adverse events and serious adverse events. Data were analysed on an intention-to-treat basis where patients with missing final outcomes were assumed to have relapsed. We calculated the risk ratio (RR) and corresponding 95% confidence interval (95% CI) for dichotomous outcomes. The Chi2 and I2 statistics were used to assess heterogeneity. The overall quality of the evidence supporting the primary outcomes and selected secondary outcomes was assessed using the GRADE criteria. Main results Seven RCTs (n = 584 patients) were included in the review. Three studies compared azathioprine to 5-aminosalicylic acid (5-ASA).One small study compared azathioprine to both 5-ASA and adalimumab. One study compared azathioprine to placebo and another study compared 6-mercaptopurine to 5-ASA and placebo. One small study compared azathioprine to infliximab. Three studies were judged to be at low risk of bias. Four studies were judged to be at high risk of bias due to blinding. The study (n = 22) comparing azathioprine to infliximab found that the effects on the proportion of patients who had a clinical (RR 2.00, 95% CI 0.21 to 18.98) or endoscopic relapse (RR 4.40, 95% CI 0.59 to 3.07) were uncertain. One study (n = 33) found decreased clinical (RR 5.18, 95% CI 1.35 to 19.83) and endoscopic relapse (RR 10.35, 95% CI 1.50 to 71.32) rates favouring adalimumab over azathioprine. A pooled analysis of two studies (n = 168 patients) showed decreased clinical relapse rates at one or two years favouring purine analogues over placebo. Forty eight per cent of patients in the purine analogue group experienced a clinical relapse compared to 63% of placebo patients (RR 0.74, 95% CI 0.58 to 0.94). A GRADE analysis indicated that the overall quality of the evidence supporting this outcome was low due to high risk of bias (one study was single-blind) and sparse data (93 events). One study (87 patients) found a reduction in endoscopic relapse rates favouring 6-mercaptopurine over placebo. Seventeen per cent of 6-mercaptopurine patients had an endoscopic relapse at two years compared to 42% of placebo patients (RR 0.40, 95% CI 0.19 to 0.83). A GRADE analysis indicated that the overall quality of the evidence for this outcome was low due to very sparse data (25 events). A pooled analysis of five studies (n = 425 patients) showed no difference in clinical relapse rates at one or two years between purine analogues and 5-ASA agents. Sixty-three per cent of patients in the purine analogues group experienced a clinical relapse compared to 54% of 5-ASA patients (RR 1.15, 95% CI 0.99 to 1.34). A GRADE analysis indicated that the overall quality of the evidence supporting this outcome was very low due to high risk of bias (two open-label studies), sparse data (249 events) and moderate heterogeneity (I2 = 45%). There was no difference in endoscopic relapse at 12 months between azathioprine and 5-ASA (RR 0.78, 95% CI 0.52 to 1.17; 1 study, 35 patients). A GRADE analysis indicated that the overall quality of the evidence for this outcome was very low due to high risk of bias (open-label study) and very sparse data (26 events). There was a reduction in endoscopic relapse at 24 months favouring 6-mercaptopurine over 5-ASA patients. Seventeen per cent of 6-mercaptopurine patients had an endoscopic relapse compared to 48% of 5-ASA patients (RR 0.36, 95% CI 0.18 to 0.72; 1 study, 91 patients). A GRADE analysis indicated that the overall quality of the evidence for this outcome was low due to very sparse data (29 events). Adverse events that required withdrawal were more common in the purine analogue group compared to 5-ASA. Twenty per cent of patients in the purine analogue group withdrew due to adverse events compared to 10% of 5-ASA patients (RR 2.07, 95% CI 1.26 to 3.39; 5 studies, 423 patients).The results for withdrawal due to adverse events between purine analogues and placebo or for other comparisons were uncertain. Commonly reported adverse events across all studies included leucopenia, arthralgia, abdominal pain or severe epigastric intolerance, elevated liver enzymes, nausea and vomiting, pancreatitis, anaemia, exacerbation of Crohn’s disease, nasopharyngitis, and flatulence. Authors’ conclusions Purine analogues may be superior to placebo for maintenance of surgically-induced remission in patients with CD, although this is based on two small studies. The results for efficacy outcomes between purine analogues and 5-ASA agents were uncertain. However, patients taking purine analogues were more likely than 5-ASA patients to discontinue therapy due to adverse events. No firm conclusions can be drawn from the two small studies that compared azathioprine to infliximab or adalimumab. Adalimumab may be superior to azathioprine but further research is needed to confirm these results. Further research investigating the efficacy and safety of azathioprine and 6-mercaptopurine in comparison to other active medications in patients with surgically-induced remission of CD is warranted

What is moving in silica at 1 K? A computer study of the low-temperature anomalies

Though the existence of two-level systems (TLS) is widely accepted to explain low temperature anomalies in many physical observables, knowledge about their properties is very rare. For silica which is one of the prototype glass-forming systems we elucidate the properties of the TLS via computer simulations by applying a systematic search algorithm. We get specific information in the configuration space, i.e. about relevant energy scales, the absolute number of TLS and electric dipole moments. Furthermore important insight about the real-space realization of the TLS can be obtained. Comparison with experimental observations is included

Chapter 4 'Now, back to our Virchow': German Medical and Political Traditions in Post-war Berlin

When the war was over in 1945, Germany was a country with no government, little functioning infrastructure, millions of refugees and homeless people, and huge foreign armies living largely off the land. Large parts of the country were covered in rubble, with no clean drinking water, electricity, or gas. Hospitals overflowed with patients, but were short of beds, medicines, and medical personnel. In these conditions, the potential for epidemics and public health disasters was severe. This is a study of how the four occupiers—Britain, France, the Soviet Union, and the United States—attempted to keep their own troops and the ex-enemy population alive. While the war was still being fought, German public health was a secondary consideration for them, an unaffordable and undeserved luxury. But once fighting ceased and the occupation began, it rapidly turned into a urgent priority. Public health was now recognized as an indispensable component of creating order, keeping the population governable, and facilitating the reconstruction of German society. But they faced a number of insoluble problems in the process: Which Germans could be trusted to work with the occupiers, and how were they to be identified? Who could be tolerated because of a lack of alternatives? How, if at all, could former Nazis be reformed and reintegrated into German society? What was the purpose of the occupation anyway? This is the first carefully researched comparison of the four occupation zones which looks at the occupation through the prism of public health, an essential service fundamentally shaped by political and economic criteria, and which in turn was to determine the success or failure of the occupation