Histograms in heavy-quark QCD at finite temperature and density

We study the phase structure of lattice QCD with heavy quarks at finite temperature and density by a histogram method. We determine the location of the critical point at which the first-order deconfining transition in the heavy-quark limit turns into a crossover at intermediate quark masses through a change of the shape of the histogram under variation of coupling parameters. We estimate the effect of the complex phase factor which causes the sign problem at finite density, and show that, in heavy-quark QCD, the effect is small around the critical point. We determine the critical surface in 2+1 flavor QCD in the heavy-quark region at all values of the chemical potential mu including mu=infty.Comment: 26 pages, 21 figures, 1 tabl

Nucleotide specificity of the enzymatic and motile activities of dynein, kinesin, and heavy meromyosin.

The substrate specificities of dynein, kinesin, and myosin substrate turnover activity and cytoskeletal filament-driven translocation were examined using 15 ATP analogues. The dyneins were more selective in their substrate utilization than bovine brain kinesin or muscle heavy meromyosin, and even different types of dyneins, such as 14S and 22S dynein from Tetrahymena cilia and the beta-heavy chain-containing particle from the outer-arm dynein of sea urchin flagella, could be distinguished by their substrate specificities. Although bovine brain kinesin and muscle heavy meromyosin both exhibited broad substrate specificities, kinesin-induced microtubule translocation varied over a 50-fold range in speed among the various substrates, whereas heavy meromyosin-induced actin translocation varied only by fourfold. With both kinesin and heavy meromyosin, the relative velocities of filament translocation did not correlate well with the relative filament-activated substrate turnover rates. Furthermore, some ATP analogues that did not support the filament translocation exhibited filament-activated substrate turnover rates. Filament-activated substrate turnover and power production, therefore, appear to become uncoupled with certain substrates. In conclusion, the substrate specificities and coupling to motility are distinct for different types of molecular motor proteins. Such nucleotide "fingerprints" of enzymatic activities of motor proteins may prove useful as a tool for identifying what type of motor is involved in powering a motility-related event that can be reconstituted in vitro

Propagation of a magnetic domain wall in magnetic wires with asymmetric notches

The propagation of a magnetic domain wall (DW) in a submicron magnetic wire consisting of a magnetic/nonmagnetic/magnetic trilayered structure with asymmetric notches was investigated by utilizing the giant magnetoresistance effect. The propagation direction of a DW was controlled by a pulsed local magnetic field, which nucleates the DW at one of the two ends of the wire. It was found that the depinning field of the DW from the notch depends on the propagation direction of the DW.Comment: 12 pages, 3 figure

Causes and Outcomes of Spontaneous Pneumothoraces in Solid Tumor Cancer Patients: An Update for the Medical Oncologist

PurposeDefined as lung collapse in the absence of a recent invasive thoracic procedure, a spontaneous pneumothorax can be a catastrophic event, leading to abrupt shortness of breath, chest pain, hypotension, and occasionally death. A dearth of present day information on this entity in solid tumor cancer patients prompted this single-institution retrospective study on current causes and outcomes.MethodsAll patients with diagnoses of “spontaneous pneumothorax” and “cancer” between 1990 and 2004 had their records retrieved and reviewed. Among 546 patients with a diagnosis of spontaneous pneumothorax, only 25 (5%) met predefined inclusion criteria that included an antecedent diagnosis of an invasive solid tumor malignancy. Lung (n = 5) and bladder cancer (n = 4) were the most common malignancies; eight patients had received radiation and one had received carmustine. Of note, 78% were smokers, 13 had chronic obstructive pulmonary disease, and 12 had no known active cancer at the time of the pneumothorax.ResultsPneumothorax management was associated with great morbidity, including hospitalization in 24 patients and chest tube placement and/or surgery in most patients. Median survival for the group as a whole was 31 months, but patients with known active cancer tended to do poorly, with only a 3-month median survival.ConclusionA spontaneous pneumothorax is rare, and patients with known active cancer tend to do poorly. However, even patients with no known active cancer are at risk, perhaps in part from smoking. The fact that patients with no known active cancer can live for years after this event suggests that the pneumothorax should not be assumed to be related to cancer recurrence, that cancer restaging is not always mandatory, and that there is justification for managing the pneumothorax in this subgroup aggressively

Origin of four-fold anisotropy in square lattices of circular ferromagnetic dots

We discuss the four-fold anisotropy of in-plane ferromagnetic resonance (FMR) field $H_r$, found in a square lattice of circular Permalloy dots when the interdot distance $a$ gets comparable to the dot diameter $d$. The minimum $H_r$, along the lattice $$axes, and the maximum, along the$$ axes, differ by $\sim$ 50 Oe at $a/d$ = 1.1. This anisotropy, not expected in uniformly magnetized dots, is explained by a non-uniform magnetization \bm(\br) in a dot in response to dipolar forces in the patterned magnetic structure. It is well described by an iterative solution of a continuous variational procedure.Comment: 4 pages, 3 figures, revtex, details of analytic calculation and new references are adde