91 research outputs found
The continuum limit of the static-light meson spectrum
We investigate the continuum limit of the low lying static-light meson
spectrum using Wilson twisted mass lattice QCD with N_f = 2 dynamical quark
flavours. We consider three values of the lattice spacing a ~ 0.051 fm, 0.064
fm, 0.080 fm and various values of the pion mass in the range 280 MeV < m_PS <
640 MeV. We present results in the continuum limit for light cloud angular
momentum j = 1/2, 3/2, 5/2 and for parity P = +, -. We extrapolate our results
to physical quark masses, make predictions regarding the spectrum of B and B_s
mesons and compare with available experimental results.Comment: 18 pages, 3 figure
Weinberg like sum rules revisited
The generalized Weinberg sum rules containing the difference of isovector
vector and axial-vector spectral functions saturated by both finite and
infinite number of narrow resonances are considered. We summarize the status of
these sum rules and analyze their overall agreement with phenomenological
Lagrangians, low-energy relations, parity doubling, hadron string models, and
experimental data.Comment: 31 pages, noticed misprints are corrected, references are added, and
other minor corrections are mad
QCD with Chemical Potential in a Small Hyperspherical Box
To leading order in perturbation theory, we solve QCD, defined on a small
three sphere in the large N and Nf limit, at finite chemical potential and map
out the phase diagram in the (mu,T) plane. The action of QCD is complex in the
presence of a non-zero quark chemical potential which results in the sign
problem for lattice simulations. In the large N theory, which at low
temperatures becomes a conventional unitary matrix model with a complex action,
we find that the dominant contribution to the functional integral comes from
complexified gauge field configurations. For this reason the eigenvalues of the
Polyakov line lie off the unit circle on a contour in the complex plane. We
find at low temperatures that as mu passes one of the quark energy levels there
is a third-order Gross-Witten transition from a confined to a deconfined phase
and back again giving rise to a rich phase structure. We compare a range of
physical observables in the large N theory to those calculated numerically in
the theory with N=3. In the latter case there are no genuine phase transitions
in a finite volume but nevertheless the observables are remarkably similar to
the large N theory.Comment: 44 pages, 18 figures, jhep3 format. Small corrections and
clarifications added in v3. Conclusions cleaned up. Published versio
The Effects of Cocaine on Different Redox Forms of Cysteine and Homocysteine, and on Labile, Reduced Sulfur in the Rat Plasma Following Active versus Passive Drug Injections
Received: 28 November 2012 / Revised: 19 April 2013 / Accepted: 6 May 2013 / Published online: 16 May 2013
The Author(s) 2013. This article is published with open access at Springerlink.comThe aim of the present studies was to evaluate
cocaine-induced changes in the concentrations of different
redox forms of cysteine (Cys) and homocysteine (Hcy),
and products of anaerobic Cys metabolism, i.e., labile,
reduced sulfur (LS) in the rat plasma. The above-mentioned
parameters were determined after i.p. acute and
subchronic cocaine treatment as well as following i.v.
cocaine self-administration using the yoked procedure.
Additionally, Cys, Hcy, and LS levels were measured
during the 10-day extinction training in rats that underwent
i.v. cocaine administration. Acute i.p. cocaine treatment
increased the total and protein-bound Hcy contents,
decreased LS, and did not change the concentrations of Cys
fractions in the rat plasma. In turn, subchronic i.p. cocaine administration significantly increased free Hcy and lowered
the total and protein-bound Cys concentrations while
LS level was unchanged. Cocaine self-administration
enhanced the total and protein-bound Hcy levels, decreased
LS content, and did not affect the Cys fractions. On the
other hand, yoked cocaine infusions did not alter the concentration
of Hcy fractions while decreased the total and
protein-bound Cys and LS content. This extinction training
resulted in the lack of changes in the examined parameters
in rats with a history of cocaine self-administration while in
the yoked cocaine group an increase in the plasma free Cys
fraction and LS was seen. Our results demonstrate for the
first time that cocaine does evoke significant changes in
homeostasis of thiol amino acids Cys and Hcy, and in some
products of anaerobic Cys metabolism, which are dependent
on the way of cocaine administration
Weak coupling large-N transitions at finite baryon density
We study thermodynamics of free SU(N) gauge theory with a large number of
colours and flavours on a three-sphere, in the presence of a baryon number
chemical potential. Reducing the system to a holomorphic large-N matrix
integral, paying specific attention to theories with scalar flavours (squarks),
we identify novel third-order deconfining phase transitions as a function of
the chemical potential. These transitions in the complex large-N saddle point
configurations are interpreted as "melting" of baryons into (s)quarks. They are
triggered by the exponentially large (~ exp(N)) degeneracy of light baryon-like
states, which include ordinary baryons, adjoint-baryons and baryons made from
different spherical harmonics of flavour fields on the three-sphere. The phase
diagram of theories with scalar flavours terminates at a phase boundary where
baryon number diverges, representing the onset of Bose condensation of squarks.Comment: 38 pages, 7 figure
Effect of four plant species on soil 15N-access and herbage yield in temporary agricultural grasslands
Positive plant diversity-productivity relationships have been reported for experimental semi-natural grasslands (Cardinale et al. 2006; Hector et al. 1999; Tilman et al. 1996) as well as temporary agricultural grasslands (Frankow-Lindberg et al. 2009; Kirwan et al. 2007; Nyfeler et al. 2009; Picasso et al. 2008). Generally, these relationships are explained, on the one hand, by niche differentiation and facilitation (Hector et al. 2002; Tilman et al. 2002) and, on the other hand, by greater probability of including a highly productive plant species in high diversity plots (Huston 1997). Both explanations accept that diversity is significant because species differ in characteristics, such as root architecture, nutrient acquisition and water use efficiency, to name a few, resulting in composition and diversity being important for improved productivity and resource use (Naeem et al. 1994; Tilman et al. 2002). Plant diversity is generally low in temporary agricultural grasslands grown for ruminant fodder production. Grass in pure stands is common, but requires high nitrogen (N) inputs. In terms of N input, two-species grass-legume mixtures are more sustainable than grass in pure stands and consequently dominate low N input grasslands (Crews and Peoples 2004; Nyfeler et al. 2009; Nyfeler et al. 2011).
In temperate grasslands, N is often the limiting factor for productivity (Whitehead 1995). Plant available soil N is generally concentrated in the upper soil layers, but may leach to deeper layers, especially in grasslands that include legumes (Scherer-Lorenzen et al. 2003) and under conditions with surplus precipitation (Thorup-Kristensen 2006). To improve soil N use efficiency in temporary grasslands, we propose the addition of deep-rooting plant species to a mixture of perennial ryegrass and white clover, which are the most widespread forage plant species in temporary grasslands in a temperate climate (Moore 2003). Perennial ryegrass and white clover possess relatively shallow root systems (Kutschera and Lichtenegger 1982; Kutschera and Lichtenegger 1992) with effective rooting depths of <0.7 m on a silt loamy site (Pollock and Mead 2008). Grassland species, such as lucerne and chicory, grow their tap-roots into deep soil layers and exploit soil nutrients and water in soil layers that the commonly grown shallow-rooting grassland species cannot reach (Braun et al. 2010; Skinner 2008). Chicory grown as a catch crop after barley reduced the inorganic soil N down to 2.5 m depth during the growing season, while perennial ryegrass affected the inorganic soil N only down to 1 m depth (Thorup-Kristensen 2006). Further, on a Wakanui silt loam in New Zealand chicory extracted water down to 1.9 m and lucerne down to 2.3 m soil depth, which resulted in greater herbage yields compared with a perennial ryegrass-white clover mixture, especially for dryland plots (Brown et al. 2005).
There is little information on both the ability of deep- and shallow-rooting grassland species to access soil N from different vertical soil layers and the relation of soil N-access and herbage yield in temporary agricultural grasslands. Therefore, the objective of the present work was to test the hypotheses 1) that a mixture comprising both shallow- and deep-rooting plant species has greater herbage yields than a shallow-rooting binary mixture and pure stands, 2) that deep-rooting plant species (chicory and lucerne) are superior in accessing soil N from 1.2 m soil depth compared with shallow-rooting plant species, 3) that shallow-rooting plant species (perennial ryegrass and white clover) are superior in accessing soil N from 0.4 m soil depth compared with deep-rooting plant species, 4) that a mixture of deep- and shallow-rooting plant species has greater access to soil N from three soil layers compared with a shallow-rooting two-species mixture and that 5) the leguminous grassland plants, lucerne and white clover, have a strong impact on grassland N acquisition, because of their ability to derive N from the soil and the atmosphere
Non-holomorphic Modular Forms and SL(2,R)/U(1) Superconformal Field Theory
We study the torus partition function of the SL(2,R)/U(1) SUSY gauged WZW
model coupled to N=2 U(1) current. Starting from the path-integral formulation
of the theory, we introduce an infra-red regularization which preserves good
modular properties and discuss the decomposition of the partition function in
terms of the N=2 characters of discrete (BPS) and continuous (non-BPS)
representations. Contrary to our naive expectation, we find a non-holomorphic
dependence (dependence on \bar{\tau}) in the expansion coefficients of
continuous representations. This non-holomorphicity appears in such a way that
the anomalous modular behaviors of the discrete (BPS) characters are
compensated by the transformation law of the non-holomorphic coefficients of
the continuous (non-BPS) characters. Discrete characters together with the
non-holomorphic continuous characters combine into real analytic Jacobi forms
and these combinations exactly agree with the "modular completion" of discrete
characters known in the theory of Mock theta functions \cite{Zwegers}.
We consider this to be a general phenomenon: we expect to encounter
"holomorphic anomaly" (\bar{\tau}-dependence) in string partition function on
non-compact target manifolds. The anomaly occurs due to the incompatibility of
holomorphy and modular invariance of the theory. Appearance of
non-holomorphicity in SL(2,R)/U(1) elliptic genus has recently been observed by
Troost \cite{Troost}.Comment: 39+1 pages, no figure; v2 a reference added, some points are
clarified, typos corrected, version to appear in JHE
Thermal properties of a string bit model at large N
We study the finite temperature properties of a recently introduced string
bit model designed to capture some features of the emergent string in the
tensionless limit. The model consists of a pair of bosonic and fermionic bit
operators transforming in the adjoint representation of the color group SU(N).
Color confinement is not achieved as a dynamical effect, but instead is
enforced by an explicit singlet projection. At large N and finite temperature,
the model has a non trivial thermodynamics. In particular, there is a Hagedorn
type transition at a finite temperature where the string degrees of
freedom are liberated and the free energy gets a large contribution that plays the role of an order parameter. For , the low
temperature phase becomes unstable. In the new phase, the thermodynamically
favoured configurations are characterized by a non-trivial gapped density of
the SU(N) angles associated with the singlet projection. We present an accurate
algorithm for the determination of the density profile at . In
particular, we determine the gap endpoint at generic temperature and analytical
expansions valid near the Hagedorn transition as well as at high temperature.
The leading order corrections are characterized by non-trivial exponents that
are determined analytically and compared with explicit numerical calculations.Comment: 15 pages, 8 pdf figure
Canakinumab relieves symptoms of acute flares and improves health-related quality of life in patients with difficult-to-treat Gouty Arthritis by suppressing inflammation: results of a randomized, dose-ranging study
INTRODUCTION: We report the impact of canakinumab, a fully human anti-interleukin-1β monoclonal antibody, on inflammation and health-related quality of life (HRQoL) in patients with difficult-to-treat Gouty Arthritis.
METHODS: In this eight-week, single-blind, double-dummy, dose-ranging study, patients with acute Gouty Arthritis flares who were unresponsive or intolerant to--or had contraindications for--non-steroidal anti-inflammatory drugs and/or colchicine were randomized to receive a single subcutaneous dose of canakinumab (10, 25, 50, 90, or 150 mg) (N = 143) or an intramuscular dose of triamcinolone acetonide 40 mg (N = 57). Patients assessed pain using a Likert scale, physicians assessed clinical signs of joint inflammation, and HRQoL was measured using the 36-item Short-Form Health Survey (SF-36) (acute version).
RESULTS: At baseline, 98% of patients were suffering from moderate-to-extreme pain. The percentage of patients with no or mild pain was numerically greater in most canakinumab groups compared with triamcinolone acetonide from 24 to 72 hours post-dose; the difference was statistically significant for canakinumab 150 mg at these time points (P < 0.05). Treatment with canakinumab 150 mg was associated with statistically significant lower Likert scores for tenderness (odds ratio (OR), 3.2; 95% confidence interval (CI), 1.27 to 7.89; P = 0.014) and swelling (OR, 2.7; 95% CI, 1.09 to 6.50, P = 0.032) at 72 hours compared with triamcinolone acetonide. Median C-reactive protein and serum amyloid A levels were normalized by seven days post-dose in most canakinumab groups, but remained elevated in the triamcinolone acetonide group. Improvements in physical health were observed at seven days post-dose in all treatment groups; increases in scores were highest for canakinumab 150 mg. In this group, the mean SF-36 physical component summary score increased by 12.0 points from baseline to 48.3 at seven days post-dose. SF-36 scores for physical functioning and bodily pain for the canakinumab 150 mg group approached those for the US general population by seven days post-dose and reached norm values by eight weeks post-dose.
CONCLUSIONS: Canakinumab 150 mg provided significantly greater and more rapid reduction in pain and signs and symptoms of inflammation compared with triamcinolone acetonide 40 mg. Improvements in HRQoL were seen in both treatment groups with a faster onset with canakinumab 150 mg compared with triamcinolone acetonide 40 mg.
TRIAL REGISTRATION: clinicaltrials.gov: NCT00798369
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