981 research outputs found
A new lower bound approach for single-machine multicriteria scheduling
The concept of maximum potential improvement has played an important role in computing lower bounds for single-machine scheduling problems with composite objective functions that are linear in the job completion times. We introduce a new method for lower bound computation; objective splitting. We show that it dominates the maximum potential improvement method in terms of speed and quality
Complexity of scheduling multiprocessor tasks with prespecified processor allocations
We investigate the computational complexity of scheduling multiprocessor tasks with prespecified processor allocations. We consider two criteria: minimizing schedule length and minimizing the sum of the task completion times. In addition, we investigate the complexity of problems when precedence constraints or release dates are involved
Growth Kinetics in a Phase Field Model with Continuous Symmetry
We discuss the static and kinetic properties of a Ginzburg-Landau spherically
symmetric model recently introduced (Phys. Rev. Lett. {\bf 75}, 2176,
(1995)) in order to generalize the so called Phase field model of Langer. The
Hamiltonian contains two invariant fields and bilinearly
coupled. The order parameter field evolves according to a non conserved
dynamics, whereas the diffusive field follows a conserved dynamics. In the
limit we obtain an exact solution, which displays an interesting
kinetic behavior characterized by three different growth regimes. In the early
regime the system displays normal scaling and the average domain size grows as
, in the intermediate regime one observes a finite wavevector
instability, which is related to the Mullins-Sekerka instability; finally, in
the late stage the structure function has a multiscaling behavior, while the
domain size grows as .Comment: 9 pages RevTeX, 9 figures included, files packed with uufiles to
appear on Phy. Rev.
Profiling for run-time checking of computational properties and performance debugging in logic programs
Although several profiling techniques for identifying performance bottlenecks in logic programs have been developed, they are generally not automatic and in most cases they do not provide enough information for identifying the root causes of such bottlenecks. This complicates using their results for guiding performance improvement. We present a profiling method and tool that provides such explanations. Our profiler associates cost centers to certain program elements and can measure different types of resource-related properties that affect performance, preserving the precedence of cost centers in the cali graph. It includes an automatic method for detecting procedures that are performance bottlenecks.
The profiling tool has been integrated in a previously developed run-time checking framework to allow verification of certain properties when they cannot be verified statically. The approach allows checking global computational properties which require complex instrumentation tracking information about previous execution states, such as, e.g., that the execution time accumulated by a given procedure is not greater than
a given bound. We have built a prototype implementation, integrated it in the Ciao/CiaoPP system and successfully applied it to performance improvement, automatic optimization (e.g., resource-aware specialization
of programs), run-time checking, and debugging of global computational properties (e.g., resource usage) in Prolog programs
Controlling collapse in Bose-Einstein condensates by temporal modulation of the scattering length
We consider, by means of the variational approximation (VA) and direct
numerical simulations of the Gross-Pitaevskii (GP) equation, the dynamics of 2D
and 3D condensates with a scattering length containing constant and
harmonically varying parts, which can be achieved with an ac magnetic field
tuned to the Feshbach resonance. For a rapid time modulation, we develop an
approach based on the direct averaging of the GP equation,without using the VA.
In the 2D case, both VA and direct simulations, as well as the averaging
method, reveal the existence of stable self-confined condensates without an
external trap, in agreement with qualitatively similar results recently
reported for spatial solitons in nonlinear optics. In the 3D case, the VA again
predicts the existence of a stable self-confined condensate without a trap. In
this case, direct simulations demonstrate that the stability is limited in
time, eventually switching into collapse, even though the constant part of the
scattering length is positive (but not too large). Thus a spatially uniform ac
magnetic field, resonantly tuned to control the scattering length, may play the
role of an effective trap confining the condensate, and sometimes causing its
collapse.Comment: 7 figure
Improved Left-Corner Chart Parsing for Large Context-Free Grammars
We develop an improved form of left-corner chart parsing for large context-free grammars, introducing improvements that result in signicant speed-ups compared to previously-known variants of left-corner parsing. We also compare our method to several other major parsing approaches, and nd that our improved left-corner parsing method outperforms each of these across a range of grammars. Finally, we also describe a new technique for minimizing the extra information needed to eĂciently recover parses from the data structures built in the course of parsing.
Mast cell deficiency limits the development of chronic rhinosinusitis in mice
Background: Chronic rhinosinusitis (CRS) is one of the most common chronic diseases in adults in both developing and developed countries. The etiology and pathogenesis of CRS remain poorly understood, and the disease is refractory to therapy in many patients. Mast cell activation has been demonstrated in the sinonasal mucosa of patients with CRS; however, the specific contribution of mast cells to the development and pathogenesis of this disease has not been established. Objective: The objective of this study was to investigate the role of mast cells in the development of CRS. Methods: C57BL/6 wild-type and C57BL/6-KitW-sh/W-sh mast cell-deficient mice were immunized by intraperitoneal allergen injection and subsequent chronic low dose intranasal allergen challenges. The sinonasal phenotypes of these groups were then evaluated and compared to saline-treated controls using radiologic, histologic, and immunologic methods. Results: Wild-type mice exposed to chronic intranasal allergen developed many features seen in human CRS, including mucosal thickening, cystic changes, polyp development, eosinophilia, goblet cell hyperplasia, and mast cell activation. In contrast, sinonasal pathology was significantly attenuated in mast cell-deficient mice subjected to the same chronic allergen protocol. Specifically, tissue eosinophilia and goblet cell hyperplasia were reduced by approximately 50% compared to wild-type levels. Surprisingly, none of the mast cell-deficient mice subjected to chronic allergen challenge developed cystic changes or polypoid changes in the nose or sinuses. Conclusions: These data identify a critical role for mast cells in the development of many features of a mouse model of eosinophilic CRS, suggesting that therapeutic strategies targeting mast cells be examined in humans afflicted with this disease
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Safety and immunogenicity of therapeutic DNA vaccination in individuals treated with antiretroviral therapy during acute/early HIV-1 infection
Background: An effective therapeutic vaccine that could augment immune control of HIV-1 replication may abrogate or delay the need for antiretroviral therapy. AIDS Clinical Trials Group (ACTG) A5187 was a phase I/II, randomized, placebo-controlled, double-blinded trial to evaluate the safety and immunogenicity of an HIV-1 DNA vaccine (VRC-HVDNA 009-00-VP) in subjects treated with antiretroviral therapy during acute/early HIV-1 infection. (clinicaltrials.gov NCT00125099) Methods: Twenty healthy HIV-1 infected subjects who were treated with antiretroviral therapy during acute/early HIV-1 infection and had HIV-1 RNA<50 copies/mL were randomized to receive either vaccine or placebo. The objectives of this study were to evaluate the safety and immunogenicity of the vaccine. Following vaccination, subjects interrupted antiretroviral treatment, and set-point HIV-1 viral loads and CD4 T cell counts were determined 17â23 weeks after treatment discontinuation. Results: Twenty subjects received all scheduled vaccinations and discontinued antiretroviral therapy at week 30. No subject met a primary safety endpoint. No evidence of differences in immunogenicity were detected in subjects receiving vaccine versus placebo. There were also no significant differences in set-point HIV-1 viral loads or CD4 T cell counts following treatment discontinuation. Median set-point HIV-1 viral loads after treatment discontinuation in vaccine and placebo recipients were 3.5 and 3.7 log[sub]10 HIV-1 RNA copies/mL, respectively. Conclusions: The HIV-1 DNA vaccine (VRC-HIVDNA 009-00-VP) was safe but poorly immunogenic in subjects treated with antiretroviral therapy during acute/early HIV-1 infection. Viral set-points were similar between vaccine and placebo recipients following treatment interruption. However, median viral load set-points in both groups were lower than in historical controls, suggesting a possible role for antiretroviral therapy in persons with acute or early HIV-1 infection and supporting the safety of discontinuing treatment in this group. Trial Registration: Clinicaltrials.gov NCT0012509
Cognitive function prior to systemic therapy and subsequent wellâbeing in older breast cancer survivors: Longitudinal findings from the Thinking and Living with Cancer Study
ObjectiveTo investigate the relationships between selfâreported and objectively measured cognitive function prior to systemic therapy and subsequent wellâbeing outcomes over 24âmonths in older breast cancer survivors.MethodsData were from 397 women aged 60 to 98 diagnosed with nonâmetastatic breast cancer in the Thinking and Living with Cancer Study recruited from 2010â2016. Cognitive function was measured at baseline (following surgery, prior to systemic therapy) using neuropsychological assessments of attention, processing speed, and executive function (APE), learning and memory (LM), and the selfâreported FACTâCog scale. Wellâbeing was measured using the FACTâG functional, physical, social, and emotional wellâbeing domain scales at baseline and 12 and 24âmonths later, scaled from 0 (low) to 100 (high). Linear mixedâeffects models assessed the relationships between each of baseline APE, LM, and FACTâCog quartiles with wellâbeing scores over 24âmonths, adjusted for confounding variables.ResultsAt baseline, older survivors in the lowest APE, LM, and FACTâCog score quartiles experienced poorer global wellâbeing than those in the highest quartiles. At 24âmonths, older survivors tended to improve in wellâbeing, and there were no differences according to baseline APE or LM scores. At 24âmonths, mean global wellâbeing was 80.3 (95% CI: 76.2â84.3) among those in the lowest vs 86.6 (95% CI: 83.1â90.1) in the highest FACTâcog quartile, a clinically meaningful difference of 6.3 points (95% CI: 1.5â11.1).ConclusionsAmong older breast cancer survivors, selfâreported, but not objective cognitive impairments, were associated with lower global wellâbeing over the first 2âyears of survivorship.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155908/1/pon5376.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155908/2/pon5376_am.pd
The 6-GHz methanol multibeam maser catalogue - I. Galactic Centre region, longitudes 345? to 6?
We have conducted a Galactic plane survey of methanol masers at 6668 MHz using a sevenbeam receiver on the Parkes telescope. Here we present results from the first part, which
provides sensitive unbiased coverage of a large region around the Galactic Centre. Details are
given for 183 methanol maser sites in the longitude range 345⊠through the Galactic Centre to
6âŠ. Within 6⊠of the Galactic Centre, we found 88 maser sites, of which more than half (48)
are new discoveries. The masers are confined to a narrow Galactic latitude range, indicative
of many sources at the Galactic Centre distance and beyond, and confined to a thin disc
population; there is no high-latitude population that might be ascribed to the Galactic bulge.
Within 2⊠of the Galactic Centre the maser velocities all lie between â60 and +77 km sâ1,
a range much smaller than the 540 km sâ1 range observed in CO. Elsewhere, the maser with
highest positive velocity (+107 km sâ1) occurs, surprisingly, near longitude 355⊠and is probably attributable to the Galactic bar. The maser with the most negative velocity (â127 km sâ1)
is near longitude 346âŠ, within the longitudeâvelocity locus of the near side of the â3-kpc armâ.
It has the most extreme velocity of a clear population of masers associated with the near and
far sides of the 3-kpc arm. Closer to the Galactic Centre the maser space density is generally
low, except within 0.25 kpc of the Galactic Centre itself, the âGalactic Centre zoneâ, where
it is 50 times higher, which is hinted at by the longitude distribution, and confirmed by the
unusual velocities.AA and DW-McS acknowledge support from a Science and Technology Facilities Council (STFC) studentship. LQ acknowledges
support from the EU Framework 6 Marie Curie Early Stage Training programme under contract MEST-CT-2005-19669 âESTRELAâ
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