Ammonia-Labile Bonds in High- and Low-Digestibility Strains of Switchgrass

Improvement in the forage quality of switchgrass (Panicum virgatum L.) through phenotypic selection for increased in vitro dry matter digestibility (IVDMD) has been demonstrated. This study tested the hypothesis that genetic improvement of fiber digestibility in switchgrass has been achieved by selection for a strain with a decreased quantity of ammonia-labile bonds. Tissue samples of a high-digestibility (high-IVDMD) and a low-digestibility strain (low-IVDMD) of switchgrass were ammoniated at rates of 0, 10, 20, and 40 g kg-1 dry matter. Fiber composition and in vitro rate and extent of neutral-detergent fiber (NDF) digestion were determined on control and ammoniated samples. The high-IVDMD strain had lower (P \u3c 0.05) concentrations of NDF and acid-detergent lignin (ADL) than the low-IVDMD strain. Lignin concentrations averaged 53 and 71 g kg-1 for the high- and low-IVDMD strains, respectively. The high-IVDMD strain had a greater (P \u3c 0.05) extent of NDF digestion when compared with the low strain; however, the rate of NDF digestion did not differ (P \u3e 0.05) between strains. Increased digestibility of the high-IVDMD strain was primarily attributed to increased cell-wall (NDF) digestibility. Ammoniation at 20 and 40 g kg-1 resulted in small decreases (P \u3c 0.05) in NDF concentrations when compared with the control; however, ammoniation had no effect on hemicellulose, cellulose, or ADL concentrations. Ammoniation increased (P \u3c 0.05) both the rate and extent of NDF digestion. Extent of NDF digestion averaged 0.395 for the control and 0.465, 0.498, and 0.493 for the 10, 20, and 40-g kg-1 treatments, respectively. Strain X ammoniation rate interaction was not significant for rate and extent of digestion, suggesting that genetic improvement in digestibility of switchgrass was not related to the number of ammonia-labile bonds

USA and RXTE Observations of a Variable Low-Frequency QPO in XTE J1118+480

The USA experiment on ARGOS and RXTE have exensively observed the X-ray transient XTE J1118+480 during its recent outburst in 2000 April--June. We present detailed monitoring of the evolution of a low frequency QPO which drifts from 0.07 Hz to 0.15 Hz during the outburst. We examine possible correlations of the QPO frequency with the flux and spectral characteristics of the source, and compare this QPO to low frequency QPOs observed in other black hole candidates.Comment: Accepted by ApJ Letters, reference added, minor revisions, 6 page

Periodic-Orbit Theory of Universality in Quantum Chaos

We argue semiclassically, on the basis of Gutzwiller's periodic-orbit theory, that full classical chaos is paralleled by quantum energy spectra with universal spectral statistics, in agreement with random-matrix theory. For dynamics from all three Wigner-Dyson symmetry classes, we calculate the small-time spectral form factor $K(\tau)$ as power series in the time $\tau$. Each term $\tau^n$ of that series is provided by specific families of pairs of periodic orbits. The contributing pairs are classified in terms of close self-encounters in phase space. The frequency of occurrence of self-encounters is calculated by invoking ergodicity. Combinatorial rules for building pairs involve non-trivial properties of permutations. We show our series to be equivalent to perturbative implementations of the non-linear sigma models for the Wigner-Dyson ensembles of random matrices and for disordered systems; our families of orbit pairs are one-to-one with Feynman diagrams known from the sigma model.Comment: 31 pages, 17 figure

Pharmacological management of unipolar depression

Objective : To be used in conjunction with ‘Psychological management of unipolar depression’ [Lampe et al. Acta Psychiatr Scand 2013;127(Suppl. 443):24–37] and ‘Lifestyle management of unipolar depression’ [Berk et al. Acta Psychiatr Scand 2013;127(Suppl. 443):38–54]. To provide clinically relevant recommendations for the use of pharmacological treatments in depression derived from a literature review.Method : Using our previous Clinical Practice Guidelines [Malhi et al. Clinical practice recommendations for bipolar disorder. Acta Psychiatr Scand 2009;119(Suppl. 439):27–46] as a foundation, these clinician guidelines target key practical considerations when prescribing pharmacotherapy. A comprehensive review of the literature was conducted using electronic database searches (PubMed, MEDLINE), and the findings have been synthesized and integrated alongside clinical experience.Results : The pharmacotherapy of depression is an iterative process that often results in partial and non-response. Beyond the initiation of antidepressants, the options within widely used strategies, such as combining agents and switching between agents, are difficult to proscribe because of the paucity of pertinent research. However, there is some evidence for second-line strategies, and a non-prescriptive algorithm can be derived that is based broadly on principles rather than specific steps.Conclusion : Depression is by its very nature a heterogeneous illness that is consequently difficult to treat. Invariably, situation-specific factors often play a significant role and must be considered, especially in the case of partial and non-response. Consulting with colleagues and trialling alternate treatment paradigms are essential strategies in the management of depression