Adiabatic Approximation in the Density Matrix Approach: Non-Degenerate Systems

We study the adiabatic limit in the density matrix approach for a quantum system coupled to a weakly dissipative medium. The energy spectrum of the quantum model is supposed to be non-degenerate. In the absence of dissipation, the geometric phases for periodic Hamiltonians obtained previously by M.V. Berry are recovered in the present approach. We determine the necessary condition satisfied by the coefficients of the linear expansion of the non-unitary part of the Liouvillian in order to the imaginary phases acquired by the elements of the density matrix, due to dissipative effects, be geometric. The results derived are model-independent. We apply them to spin 1/2 model coupled to reservoir at thermodynamic equilibrium.Comment: 24 pages (new version), accepted for publication in Physica

The high temperature expansion of the classical XYZXYZ chain

We present the $\beta$-expansion of the Helmholtz free energy of the classical $XYZ$ model, with a single-ion anisotropy term and in the presence of an external magnetic field, up to order $\beta^{12}$. We compare our results to the numerical solution of Joyce's [Phys. Rev. Lett. 19, 581 (1967)] expression for the thermodynamics of the $XXZ$ classical model, with neither single-ion anisotropy term nor external magnetic field. This comparison shows that the derived analytical expansion is valid for intermediate temperatures such as $kT/J_x \approx 0.5$. We show that the specific heat and magnetic susceptibility of the spin-2 antiferromagnetic chain can be approximated by their respective classical results, up to $kT/J \approx 0.8$, within an error of 2.5%. In the absence of an external magnetic field, the ferromagnetic and antiferromagnetic chains have the same classical Helmholtz free energy. We show how this two types of media react to the presence of an external magnetic field

Universality of the Operator Product Expansions of SCFT_4

We study the operator product algebra of the supercurrent J and Konishi superfield K in four-dimensional supersymmetric gauge theories. The Konishi superfield appears in the JJ OPE and the algebra is characterized by two central charges c and c' and an anomalous dimension h for K. In free field (one-loop) approximation, c~3N_v+N_\chi and c'~N_\chi, where N_v and N_\chi are, respectively, the number of vector and chiral multiplets in the theory. In higher order c, c' and h depend on the gauge and Yukawa couplings and we obtain the two-loop contributions by combining earlier work on c with our own calculations of c'. The major result is that the radiative corrections to the central charges cancel when the one-loop beta-functions vanish, suggesting that c and c' (but not h) are invariant under continuous deformations of superconformal theories. The behavior of c and c' along renormalization group flows is studied from the viewpoint of a c-theorem.Comment: LaTeX file, 11 pages, no figur

Nonlinear time-series analysis of Hyperion's lightcurves

Hyperion is a satellite of Saturn that was predicted to remain in a chaotic rotational state. This was confirmed to some extent by Voyager 2 and Cassini series of images and some ground-based photometric observations. The aim of this aticle is to explore conditions for potential observations to meet in order to estimate a maximal Lyapunov Exponent (mLE), which being positive is an indicator of chaos and allows to characterise it quantitatively. Lightcurves existing in literature as well as numerical simulations are examined using standard tools of theory of chaos. It is found that existing datasets are too short and undersampled to detect a positive mLE, although its presence is not rejected. Analysis of simulated lightcurves leads to an assertion that observations from one site should be performed over a year-long period to detect a positive mLE, if present, in a reliable way. Another approach would be to use 2---3 telescopes spread over the world to have observations distributed more uniformly. This may be achieved without disrupting other observational projects being conducted. The necessity of time-series to be stationary is highly stressed.Comment: 34 pages, 12 figures, 4 tables; v2 after referee report; matches the version accepted in Astrophysics and Space Scienc

Systematics of Malaysian woolly bats (Vespertilionidae: Kerivoula) inferred from mitochondrial, nuclear, karyotypic, and morphological data

Examining species boundaries using data from multiple independent sources is an appropriate and robust method to identify genetically isolated evolutionary units. We used 5 data sets—cytochrome b (Cytb), cytochrome c oxidase (COI), amplified fragment length polymorphisms (AFLPs), karyotypes, and morphology—to estimate phylogenetic relationships and species limits within woolly bats, genus Kerivoula, from Southeast Asia. We genetically analyzed 54 specimens of Kerivoula from Malaysia, assigned to 6 of the 10 species currently reported from the country. Phylogenetic analyses of nuclear AFLPs (33 specimens) and mitochondrial DNA sequences from Cytb (51 specimens) and COI (48 specimens) resulted in similar statistically supported species-level clades with minimal change in branching order. Using comparisons of cranial and dental morphology and original species descriptions, we assigned the resulting phylogenetic clades to K hardwickii, K. intermedia, K. lenis, K. minuta, K. papillosa, K pellucida, and 1 unidentified species. Karyotypes further documented variability among the 6 clades. Five different karyotypes were identified, with 2 species having indistinguishable karyotypes. We compared our COI gene sequence data to 110 specimens of Kerivoula from Southeast Asia made available by researchers of the Barcode of Life Database. Our Cytb and AFLP species identifications were congruent with those in the COI database. Intraspecific geographic variation of about 5–7% sequence divergence was observed in Cytb and COI genes within both K. hardwickii and K. minuta. Relaxed molecular clock analyses indicated a late Oligocene to early Miocene origin of the Kerivoulinae with intraspecific diversification events coinciding with the late Pliocene and Pleistocene epochs in at least 6 species. Specimens from Sabah (northeastern Borneo) showed relatively high genetic divergence compared to those between Peninsular Malaysia and Sarawak (southwestern Borneo), indicating Pleistocene or Pliocene refugia in Borneo. We conclude that at least 1 distinct lineage of Kerivoula is yet to be described from Borneo and that the intraspecific geographic variation in some species agrees with previous studies on the diversification of flora and fauna in Borneo. Key word

Determination of the uptake and translocation of nitrogen applied at different growth stages of a melon crop (Cucumis melo L.) using 15N isotope.

In order to establish a rational nitrogen (N) fertilisation and reduce groundwater contamination, a clearer understanding of the N distribution through the growing season and its dynamics inside the plant is crucial. In two successive years, a melon crop (Cucumis melo L. cv. Sancho) was grown under field conditions to determine the uptake of N fertiliser, applied by means of fertigation at different stages of plant growth, and to follow the translocation of N in the plant using 15N-labelled N. In 2006, two experiments were carried out. In the first experiment, labelled 15N fertiliser was supplied at the female-bloom stage and in the second, at the end of fruit ripening. Labelled 15N fertiliser was made from 15NH415NO3 (10 at.% 15N) and 9.6 kg N ha−1 were applied in each experiment over 6 days (1.6 kg N ha−1 d−1). In 2007, the 15N treatment consisted of applying 20.4 kg N ha−1 as 15NH415NO3 (10 at.% 15N) in the middle of fruit growth, over 6 days (3.4 kg N ha−1 d−1). In addition, 93 and 95 kg N ha−1 were supplied daily by fertigation as ammonium nitrate in 2006 and 2007, respectively. The results obtained in 2006 suggest that the uptake of N derived from labelled fertiliser by the above-ground parts of the plants was not affected by the time of fertiliser application. At the female-flowering and fruit-ripening stages, the N content derived from 15N-labelled fertiliser was close to 0.435 g m−2 (about 45% of the N applied), while in the middle of fruit growth it was 1.45 g m−2 (71% of the N applied). The N application time affected the amount of N derived from labelled fertiliser that was translocated to the fruits. When the N was supplied later, the N translocation was lower, ranging between 54% at female flowering and 32% at the end of fruit ripening. Approximately 85% of the N translocated came from the leaf when the N was applied at female flowering or in the middle of fruit growth. This value decreased to 72% when the 15N application was at the end of fruit ripening. The ammonium nitrate became available to the plant between 2 and 2.5 weeks after its application. Although the leaf N uptake varied during the crop cycle, the N absorption rate in the whole plant was linear, suggesting that the melon crop could be fertilised with constant daily N amounts until 2–3 weeks before the last harvest

GC-MS Techniques Investigating Potential Biomarkers of Dying in the Last Weeks with Lung Cancer

Predicting when a patient with advanced cancer is dying is a challenge and currently no prognostic test is available. We hypothesised that a dying process from cancer is associated with metabolic changes and specifically with changes in volatile organic compounds (VOCs). We analysed urine from patients with lung cancer in the last weeks of life by headspace gas chromatography mass spectrometry. Urine was acidified or alkalinised before analysis. VOC changes in the last weeks of life were identified using univariate, multivariate and linear regression analysis; 12 VOCs increased (11 from the acid dataset, 2 from the alkali dataset) and 25 VOCs decreased (23 from the acid dataset and 3 from the alkali dataset). A Cox Lasso prediction model using 8 VOCs predicted dying with an AUC of 0.77, 0.78 and 0.85 at 30, 20 and 10 days and stratified patients into a low (median 10 days), medium (median 50 days) or high risk of survival. Our data supports the hypothesis there are specific metabolic changes associated with the dying. The VOCs identified are potential biomarkers of dying in lung cancer and could be used as a tool to provide additional prognostic information to inform expert clinician judgement and subsequent decision making

Functionally overlapping variants control tuberculosis susceptibility in collaborative cross mice

Host genetics plays an important role in determining the outcome of Mycobacterium tuberculosis infection. We previously found that Collaborative Cross (CC) mouse strains differ in their susceptibility to M. tuberculosis and that the CC042/ GeniUnc (CC042) strain suffered from a rapidly progressive disease and failed to produce the protective cytokine gamma interferon (IFN-γ) in the lung. Here, we used parallel genetic and immunological approaches to investigate the basis of CC042 mouse susceptibility. Using a population derived from a CC001/Unc (CC001) × CC042 intercross, we mapped four quantitative trait loci (QTL) underlying tuberculosis immunophenotypes (Tip1 to Tip4). These included QTL that were associated with bacterial burden, IFN-γ production following infection, and an IFN-γ-independent mechanism of bacterial control. Further immunological characterization revealed that CC042 animals recruited relatively few antigen-specific T cells to the lung and that these T cells failed to express the integrin alpha L (αL; i.e., CD11a), which contributes to T cell activation and migration. These defects could be explained by a CC042 private variant in the Itgal gene, which encodes CD11a and is found within the Tip2 interval. This 15-bp deletion leads to aberrant mRNA splicing and is predicted to result in a truncated protein product. The ItgalCC042 genotype was associated with all measured disease traits, indicating that this variant is a major determinant of susceptibility in CC042 mice. The combined effect of functionally distinct Tip variants likely explains the profound susceptibility of CC042 mice and highlights the multigenic nature of tuberculosis control in the Collaborative Cross. IMPORTANCE The variable outcome of Mycobacterium tuberculosis infection observed in natural populations is difficult to model in genetically homogeneous small-animal models. The newly developed Collaborative Cross (CC) represents a reproducible panel of genetically diverse mice that display a broad range of phenotypic responses to infection. We explored the genetic basis of this variation, focusing on a CC line that is highly susceptible to M. tuberculosis infection. This study identified multiple quantitative trait loci associated with bacterial control and cytokine production, including one that is caused by a novel loss-of-function mutation in the Itgal gene, which is necessary for T cell recruitment to the infected lung. These studies verify the multigenic control of mycobacterial disease in the CC panel, identify genetic loci controlling diverse aspects of pathogenesis, and highlight the utility of the CC resource

Using Genetics and Morphology to Examine Species Diversity of Old World Bats: Report of a Recent Collection from Malaysia

A three-week field survey was conducted to sample bat species diversity in Malaysia. The survey sampled five localities during August 2006, including one in Peninsular Malaysia and four in Borneo. A total of 259 specimens representing at least 50 species were recorded. Three sampling nights were spent at each locality; four harp traps and 15 mist nets were set most nights. The highest species diversity was recorded in Mount Penrisen (Borneo) with 27 species, whereas the lowest diversity was at Monggis Sub Station and Bako National Park (Borneo) with 13 species each. We added four new geographic records for Sarawak, Malaysian Borneo: Arielulus cuprosus, Hesperoptenus tomesi, Kerivoula lenis, and Myotis adversus; and the second record of Hipposideros doriae in Sarawak. Other findings included a colony of earwigs collected from an Eonycteris major and the documentation of highly developed facial glands on male Hipposideros ater and H. galeritus. Species were identified using traditional skin and skull characteristics as well as mitochondrial cytochrome-b gene sequences that were compared to existing GenBank records. This multifaceted approach, using genetic and morphological identifications, has provided greater resolution to species identification as well as a better understanding of the diversification of Old World Bats from Malaysia. Although in most cases genetic data validated the present taxonomy, there were still a number of cases of cryptic species suggesting an underestimation of the actual biodiversity. This study has demonstrated the value of genetic data in providing an independent test for species boundaries among the 50 species of bats collected (about 40% of the known Malaysian bat fauna)