Intermediate-statistics spin waves

In this paper, we show that spin waves, the elementary excitation of the Heisenberg magnetic system, obey a kind of intermediate statistics with a finite maximum occupation number n. We construct an operator realization for the intermediate statistics obeyed by magnons, the quantized spin waves, and then construct a corresponding intermediate-statistics realization for the angular momentum algebra in terms of the creation and annihilation operators of the magnons. In other words, instead of the Holstein-Primakoff representation, a bosonic representation subject to a constraint on the occupation number, we present an intermediate-statistics representation with no constraints. In this realization, the maximum occupation number is naturally embodied in the commutation relation of creation and annihilation operators, while the Holstein-Primakoff representation is a bosonic operator relation with an additional putting-in-by-hand restriction on the occupation number. We deduce the intermediate-statistics distribution function for magnons. On the basis of these results, we calculate the dispersion relations for ferromagnetic and antiferromagnetic spin waves. The relations between the intermediate statistics that magnons obey and the other two important kinds of intermediate statistics, Haldane-Wu statistics and the fractional statistics of anyons, are discussed. We also compare the spectrum of the intermediate-statistics spin wave with the exact solution of the one-dimensional s = 1/2 Heisenberg model, which is obtained by the Bethe ansatz method. For ferromagnets, we take the contributions from the interaction between magnons (the quartic contribution), the next-to-nearest neighbor interaction, and the dipolar interaction into account for comparison with the experiment.Comment: 22 pages, 2 figure

Body Acupuncture for Nicotine Withdrawal Symptoms: A Randomized Placebo-controlled Trial

This study evaluated whether improvements in nicotine withdrawal symptoms (NWS), depression and anxiety are greater for body acupuncture than for sham acupuncture. Smoking volunteers from the public were randomized to receive six sessions of either real or sham acupuncture for 2 weeks. The primary outcome measure was NWS measured by the Minnesota Nicotine Withdrawal Score, and the secondary measures were scores on the Beck Depression Inventory (BDI) and Beck Anxiety Inventory (BAI). Eighty volunteers were randomized into real acupuncture (n = 38) and sham acupuncture (n = 42) groups, of which 46 subjects (22 and 24 in the real and sham acupuncture groups, respectively) completed the treatment and the 2-week follow-up. An intention-to-treat analysis revealed that the NWS did not differ significantly between the real and sham acupuncture groups immediately after the treatment (12.2 ± 9.7 and 12.8 ± 7.7, respectively; mean ± SD) and at the 2-week follow-up (11.7 ± 10.2 and 12.6 ± 7.8). Both groups also showed similar improvements in BDI and BAI scores. These results indicate that the real acupuncture treatment tested in this trial was no more effective than sham acupuncture at reducing NWS, depression and anxiety for smoking cessation

A multi-exon deletion within WWOX is associated with a 46,XY disorder of sex development

Disorders of sex development (DSD) are congenital conditions where chromosomal, gonad or genital development is atypical. In a significant proportion of 46,XY DSD cases it is not possible to identify a causative mutation, making genetic counseling difficult and potentially hindering optimal treatment. Here, we describe the analysis of a 46,XY DSD patient that presented at birth with ambiguous genitalia. Histological analysis of the surgically removed gonads showed bilateral undifferentiated gonadal tissue and immature testis, both containing malignant germ cells. We screened genomic DNA from this patient for deletions and duplications using an Illumina whole-genome SNP microarray. This analysis revealed a heterozygous deletion within the WWOX gene on chromosome 16, removing exons 6-8. Analysis of parental DNA showed that the deletion was inherited from the mother. cDNA analysis confirmed that the deletion maintained the reading frame, with exon 5 being spliced directly onto exon 9. This deletion is the first description of a germline rearrangement affecting the coding sequence of WWOX in humans. Previously described Wwox knockout mouse models showed gonadal abnormalities, supporting a role for WWOX in human gonad development

Electronic transport in polycrystalline graphene

Most materials in available macroscopic quantities are polycrystalline. Graphene, a recently discovered two-dimensional form of carbon with strong potential for replacing silicon in future electronics, is no exception. There is growing evidence of the polycrystalline nature of graphene samples obtained using various techniques. Grain boundaries, intrinsic topological defects of polycrystalline materials, are expected to dramatically alter the electronic transport in graphene. Here, we develop a theory of charge carrier transmission through grain boundaries composed of a periodic array of dislocations in graphene based on the momentum conservation principle. Depending on the grain boundary structure we find two distinct transport behaviours - either high transparency, or perfect reflection of charge carriers over remarkably large energy ranges. First-principles quantum transport calculations are used to verify and further investigate this striking behaviour. Our study sheds light on the transport properties of large-area graphene samples. Furthermore, purposeful engineering of periodic grain boundaries with tunable transport gaps would allow for controlling charge currents without the need of introducing bulk band gaps in otherwise semimetallic graphene. The proposed approach can be regarded as a means towards building practical graphene electronics.Comment: accepted in Nature Material

Do patients and carers agree on symptom burden in advanced COPD?

OBJECTIVE: Accurate informal carer assessment of patient symptoms is likely to be valuable for decision making in managing the high symptom burden of COPD in the home setting. Few studies have investigated agreement between patients and carers in COPD. We aimed to assess agreement between patients and carers on symptoms, and factors associated with disagreement in a population-based sample of patients with advanced COPD. PATIENTS AND METHODS: This was a prospective, cross-sectional analysis of data from 119 advanced COPD patients and their carers. Patients and carers separately rated symptoms on a 4-point scale. Wilcoxon signed-rank tests and weighted Cohen's kappa determined differences in patient and carer scores and patient-carer agreement, respectively. We identified characteristics associated with incongruence using Spearman's rank correlation and Mann-Whitney U tests. RESULTS: There were no significant differences between group-level patient and carer scores for any symptom. Patient-carer individual-level agreement was moderate for constipation (k=0.423), just below moderate for diarrhea (k=0.393) and fair for depression (k=0.341), fatigue (k=0.294), anxiety (k=0.289) and breathlessness (k=0.210). Estimation of greater patient symptom burden by carers relative to patients themselves was associated with non-spousal patient-carer relationship, non-cohabitating patients and carers, carer symptoms of anxiety and depression and more carer unmet support needs. Greater symptom burden estimation by the patient relative to the carer was associated with younger patients and longer duration of COPD. CONCLUSION: Overall, agreement between patients and carers was fair to moderate and was poorer for more subjective symptoms. There is a need to encourage open dialogue between patients and carers to promote shared understanding, help patients express themselves and encourage carers to draw attention to symptoms that patients do not report. The findings suggest a need to screen for and address both the psychological morbidities in patients with advanced COPD and their carers and unmet support needs in carers

Randomized Clinical Trials of Constitutional Acupuncture: A Systematic Review

The aim of this systematic review is to compile and critically evaluate the evidence from randomized clinical trials (RCTs) for the effectiveness of acupuncture using constitutional medicine compared to standard acupuncture. Ten databases were searched through to December 2008 without language restrictions. We also hand-searched nine Korean journals of oriental medicine. We included prospective RCTs of any form of acupuncture with or without electrical stimulation. The included trials had to investigate constitutional medicine. There were no restrictions on population characteristics. Forty-one relevant studies were identified, and three RCTs were included. The methodological quality of the trials was variable. One RCT found Sasang constitutional acupuncture to be superior to standard acupuncture in terms of the Unified PD Rating Scale and freezing gate in Parkinson's disease (PD). Another two RCTs reported favorable effects of eight constitutional acupuncture on pain reduction in patients with herniated nucleus pulposi and knee osteoarthritis. Meta-analysis demonstrated positive results for eight constitutional acupuncture compared to standard acupuncture on pain reduction (weighted mean difference: 10 cm VAS, 1.69, 95% CI 0.85–2.54, P < 0.0001; heterogeneity: τ2 = 0.00, χ2 = 0.00, P = 0.96, I2 = 0%). Our results provide suggestive evidence for the effectiveness of constitutional acupuncture in treating pain conditions compared to standard acupuncture. However, the total number of RCTs and the total sample size included in our analysis were too small to draw definite conclusions. Future RCTs should assess larger patient samples with longer treatment periods and appropriate controls

Epiparasitic plants specialized on arbuscular mycorrhizal fungi

Over 400 non-photosynthetic species from 10 families of vascular plants obtain their carbon from fungi and are thus defined as myco-heterotrophs. Many of these plants are epiparasitic on green plants from which they obtain carbon by 'cheating' shared mycorrhizal fungi. Epiparasitic plants examined to date depend on ectomycorrhizal fungi for carbon transfer and exhibit exceptional specificity for these fungi, but for most myco-heterotrophs neither the identity of the fungi nor the sources of their carbon are known. Because many myco-heterotrophs grow in forests dominated by plants associated with arbuscular mycorrhizal fungi (AMF; phylum Glomeromycota), we proposed that epiparasitism would occur also between plants linked by AMF. On a global scale AMF form the most widespread mycorrhizae, thus the ability of plants to cheat this symbiosis would be highly significant. We analysed mycorrhizae from three populations of Arachnitis uniflora (Corsiaceae, Monocotyledonae), five Voyria species and one Voyriella species (Gentianaceae, Dicotyledonae), and neighbouring green plants. Here we show that non-photosynthetic plants associate with AMF and can display the characteristic specificity of epiparasites. This suggests that AMF mediate significant inter-plant carbon transfer in nature

An efficient semiparametric maxima estimator of the extremal index

The extremal index $\theta$, a measure of the degree of local dependence in the extremes of a stationary process, plays an important role in extreme value analyses. We estimate $\theta$ semiparametrically, using the relationship between the distribution of block maxima and the marginal distribution of a process to define a semiparametric model. We show that these semiparametric estimators are simpler and substantially more efficient than their parametric counterparts. We seek to improve efficiency further using maxima over sliding blocks. A simulation study shows that the semiparametric estimators are competitive with the leading estimators. An application to sea-surge heights combines inferences about $\theta$ with a standard extreme value analysis of block maxima to estimate marginal quantiles.Comment: 17 pages, 7 figures. Minor edits made to version 1 prior to journal publication. The final publication is available at Springer via http://dx.doi.org/10.1007/s10687-015-0221-