1,129 research outputs found
On the reduction of the degree of linear differential operators
Let L be a linear differential operator with coefficients in some
differential field k of characteristic zero with algebraically closed field of
constants. Let k^a be the algebraic closure of k. For a solution y, Ly=0, we
determine the linear differential operator of minimal degree M and coefficients
in k^a, such that My=0. This result is then applied to some Picard-Fuchs
equations which appear in the study of perturbations of plane polynomial vector
fields of Lotka-Volterra type
On Kink-Dynamics of Stacked-Josephson Junctions
Dynamics of a fluxon in a stack of coupled long Josephson junctions is studied numericallv. Based on the numerical simulations, we show that the dependence of the propagation velocity c on the external bias current ĂÂł is determined by the ratio of the critical currents of thc two junctions J
Further studies on the effect of fat supplementation of concentrates fed to lactating dairy cows. II. Total digestion and energy utilization.
For wether sheep given 300 g hay and 800 g concentrates the addition of fat (beef tallow:palm kernel oil 9:1) to concentrates at 7 or 12% tended to decrease crude fibre digestibility and increased crude fat digestibility. For 2 rumen-fistulated cows given concentrates containing 7% fat, or 12% fat free or adsorbed on carrier, and 2 cows with fistulae and reentrant duodenal cannulae given concentrates with 12% fat in rations with hay:concentrate 1:2, there were no significant differences between diets in the digestibility of any nutrient; fat digestibility was decreased at feed intakes above maintenance, particularly with the 12% fat concentrates. The use of a carrier in the 12% fat concentrates did not affect nutrient digestibilities for sheep or cows. Inclusion of fat in concentrates increased the metabolizability of sheep diets but there were no significant differences among cattle diets, although methane losses tended to decrease as fat content increased. Additional energy from fat tended to be retained rather than used for milk yield. ME utilization for milk, storage and maintenance was 61-62.5%, tending to be highest with the 12% adsorbed fat. [See DSA 45, 5398 for part I.] (Abstract retrieved from CAB Abstracts by CABIâs permission
Properties of Semi-Chiral Superfields
Whenever the N=(2,2) supersymmetry algebra of non-linear sigma-models in two
dimensions does not close off-shell, a holomorphic two-form can be defined. The
only known superfields providing candidate auxiliary fields to achieve an
off-shell formulation are semi-chiral fields. Such a semi-chiral description is
only possible when the two-form is constant. Using an explicit example,
hyper-Kahler manifolds, we show that this is not always the case. Finally, we
give a concrete construction of semi-chiral potentials for a class of
hyper-Kahler manifolds using the duality exchanging a pair consisting of a
chiral and a twisted-chiral superfield for one semi-chiral multiplet.Comment: LaTeX, 17 page
Oscillatory eigenmodes and stability of one and two arbitrary fractional vortices in long Josephson 0-kappa-junctions
We investigate theoretically the eigenmodes and the stability of one and two
arbitrary fractional vortices pinned at one and two -phase
discontinuities in a long Josephson junction. In the particular case of a
single -discontinuity, a vortex is spontaneously created and pinned at
the boundary between the 0 and -regions. In this work we show that only
two of four possible vortices are stable. A single vortex has an oscillatory
eigenmode with a frequency within the plasma gap. We calculate this
eigenfrequency as a function of the fractional flux carried by a vortex.
For the case of two vortices, pinned at two -discontinuities situated
at some distance from each other, splitting of the eigenfrequencies occur.
We calculate this splitting numerically as a function of for different
possible ground states. We also discuss the presence of a critical distance
below which two antiferromagnetically ordered vortices form a strongly coupled
``vortex molecule'' that behaves as a single object and has only one eigenmode.Comment: submitted to Phys. Rev. B (
Controllable plasma energy bands in a 1D crystal of fractional Josephson vortices
We consider a 1D chain of fractional vortices in a long Josephson junction
with alternating phase discontinuities. Since each vortex has its
own eigenfrequency, the inter-vortex coupling results in eigenmode splitting
and in the formation of an oscillatory energy band for plasma waves. The band
structure can be controlled at the design time by choosing the distance between
vortices or \emph{during experiment} by varying the topological charge of
vortices or the bias current. Thus one can construct an artificial vortex
crystal with controllable energy bands for plasmons.Comment: 4 pages, 2 Fig
Clinical response correlates with 4-week postinjection ustekinumab concentrations in patients with moderate-to-severe psoriasis
Background: Costâeffective use of biologicals is important. As drug concentrations have been linked to clinical outcomes, monitoring drug concentrations is a valuable tool to guide clinical decisionâmaking. A concentrationâresponse relationship for ustekinumab at trough is uncertain owing to the contradictory results reported.
Objectives: To investigate the relationship between 4âweek postinjection ustekinumab concentrations and clinical response in patients with psoriasis.
Methods: Fortyânine patients with moderateâtoâsevere psoriasis treated with 45 mg or 90 mg ustekinumab every 12 weeks for â„ 16 weeks were included. Ustekinumab serum concentrations and antiâustekinumab antibodies were measured at week 4 after injection and disease severity was assessed by Psoriasis Area and Severity Index (PASI).
Results: At week 4 after injection, a significantly negative correlation was observed between ustekinumab concentrations and absolute PASI score up to 5·9 ÎŒg mLâ1 (Ï = â0·357, P = 0·032). Ustekinumab concentrations were higher in optimal responders (PASI †2) than in suboptimal responders (PASI > 2) (4·0 vs 2·8 ÎŒg mLâ1, P = 0·036). The ustekinumab concentration threshold associated with optimal response was determined to be 3·6 ÎŒg mLâ1 (area under the curve 0·71, sensitivity 86%, specificity 63%). Only one patient (2%) had antiâustekinumab antibodies. Psoriatic arthritis was identified as an independent predictor of higher PASI scores and higher ustekinumab concentrations (P = 0·003 and P = 0·048, respectively).
Conclusions: A concentrationâresponse relationship at week 4 after injection was observed for patients with psoriasis treated with ustekinumab. Monitoring 4âweek postinjection ustekinumab concentrations could timely identify underexposed patients who might benefit from treatment optimization
Individual diet differences in a molluscivore shorebird are associated with the size of body instruments for internal processing rather than for feeding
Especially in birds, it is widely found that the size of individual prey items follows the size of the instruments of prey capture, handling and processing, i.e. bill size. In fact, this is the natural history basis of major discoveries on adaptive evolution in the face of changing food resources. In some birds, e.g. the molluscivore shorebirds ingesting hard-shelled prey, most of the prey processing takes place within the digestive tract. This study of a salvaged sample of actively feeding great knots Calidris tenuirostris accidentally drowned in fishing nets in northern China, is the first documentation of diet selection at the level of the individual in previously well-studied molluscivore shorebirds. Diet composition was not associated with the length of the bill, but with the mass of the muscular gizzard. Gizzard mass, which unlike bill length is a phenotypically flexible trait, enables great knots to adjust to changing food resources as an individual, i.e. instantly responding to the food on offer. For migratory species like great knots which rely on seasonal sequences of interdistant feeding areas offering prey with a variety of characteristics, the capacity to individually adjust appears a key adaptation
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