1,630 research outputs found
The Three Faces of the Second Law: II. Fokker-Planck Formulation
The total entropy production is the sum of two contributions, the so-called
adiabatic and nonadiabatic entropy production, each of which is non-negative.
We derive their explicit expressions for continuous Markov processes, discuss
their properties and illustrate their behavior on two exactly solvable models.Comment: 7 pages, 1 figur
Chiral Brownian heat pump
We present the exact analysis of a chiral Brownian motor and heat pump.
Optimization of the construction predicts, for a nanoscale device, frequencies
of the order of kHz and cooling rates of the order of femtojoule per second.Comment: Submitted to Phys. Rev. Let
A `warp drive' with more reasonable total energy requirements
I show how a minor modification of the Alcubierre geometry can dramatically
improve the total energy requirements for a `warp bubble' that can be used to
transport macroscopic objects. A spacetime is presented for which the total
negative mass needed is of the order of a few solar masses, accompanied by a
comparable amount of positive energy. This puts the warp drive in the mass
scale of large traversable wormholes. The new geometry satisfies the quantum
inequality concerning WEC violations and has the same advantages as the
original Alcubierre spacetime.Comment: 9 pages, 1 figure; error in calculation correcte
Differences in shell morphology and reproductive impairment in <i>Littorina littorea</i> along the Belgian coast
In this study we evaluated the condition of Littorina littorea along the Belgian coast using shell morphology and reproductive impairment (i.e. female intersex and sterility; male penis shedding) characteristics. Periwinkles were collected at eight sites along the Belgian coast of which three were in the direct vicinity of the seaports of ‘Zeebrugge’, ‘Oostende’ and ‘Nieuwpoort’. Standard shell parameters were measured, animals were sexed based on the p/a of the vesicula seminalis and reproductive impairment was determined for both sexes. Significant differences in the shell morphology and reproductive impairment could be detected among the sites. Indeed, periwinkles from ‘Zeebrugge’ were significantly larger and heavier compared to the specimens that were taken from the other sites. In addition, ‘Zeebrugge’ contained the largest number of penis shedded males (i.e. 61.11%) and intersex/sterile females (i.e. 100% and 95.24% respectively). The latter resulted in an ISI-index of 3.52, which is one of the highest ISI values ever recorded in L. littorea
Effects of environmental stress on the condition of <i>Littorina littorea</i> along the Scheldt Estuary (the Netherlands)
The condition of the periwinkle Littorina littorea, expressed in terms of its shell morphology, reproductive impairment (i.e. female sterility/intersex, male penis shedding), trematode infestation load, lipid reserves and dry/wet weight ratio, was determined in function of environmental stress along the polluted Western and relatively clean Eastern Scheldt estuary (The Netherlands). The upstream increasing pollution and decreasing salinity levels along the Western Scheldt estuary (Fig. 1) are reflected in the dry/wet weight ratio and lipid content of the periwinkles. Compared to the Eastern Scheldt, female intersex (i.e. indicator of TBT pollution) and sterility occurred more frequently in the Western Scheldt estuary, while male penis shedding was even restricted to the latter estuary. The highest population intersex and sterility incidence was found near the harbour of Vlissingen and reflects potential nautical activities. The number of trematode infested periwinkles did not differ between both estuaries, although local sampling site differences were detected within each estuary, reflecting the complex interactions that exist among parasites, hosts and the local environment. Finally, both estuaries were maximally discriminated from each other based on the shell weight of the periwinkles using a canonical discriminant analysis. Periwinkles with the heaviest shells were found in the Western Scheldt estuary and may reflect growth rate or structural population differences caused by the less favourable living conditions in the Western Scheldt estuary
Assessment of the myoglobin variation in the periwinkle <i>Littorina littorea</i> along the Scheldt estuary
The Scheldt estuary (The Netherlands) consists of two tributaries, of which the western part is heavily polluted (i.e. domestic and industrial pollutants, including heavy metals) and the eastern is relatively clean. Pollutants generally follow downstream decreasing concentration gradients, thus opposing a natural occurring salinity gradient, which decreases upstream. Hence, the Scheldt estuary forms an interesting setting to investigate the effects of both anthropogenic and natural kind.The population genetic structure of the periwinkle, Littorina littorea, has already been studied in this estuary using esterases and RAPD markers. Both studies revealed an estuary based genetic structuring. This genetic patterning is unexpected since L. littorea has a planktonic larval development and thus little genetic differentiation is expected. However, radular myoglobin studies have shown intraspecific variation in L. littorea on a macrogeographical scale. In this contribution, myoglobin profiles of the radular muscle were phenotypically analysed along the Scheldt estuary, using isoelectric focusing.A total of 395 periwinkles, descending from four eastern estuarine, five western estuarine and one marine sampling site were collected and morphometrically characterized after which their individual Mb profile was determined. Four Mb bands could be identified and the distribution of each of these bands differed significantly between the western and eastern Scheldt estuary. In addition, eight different Mb phenotypes were detected of which the distribution differed between both estuaries as well, yielding a significantly higher phenotypic variability in the Western Scheldt. A Dice similarity distance based multidimensional scaling minimum spanning tree (MDS-MST) analysis revealed no clear differentiation between both estuaries. Likewise the MDS-MST analysis failed to detect phenotypic structuring along the pollution-salinity gradient of the Western Scheldt sampling sites. However, the only marine sampling site was clearly separated from the nine remaining estuarine locations in the MDS-MST plot. These preliminary data suggest, in the presence of intense gene flow, (1) a high level of phenotypic Mb variability and (2) a marine versus estuarine phenotypic Mb structuring
Dissipative collapse of the adiabatic piston
An adiabatic piston, separating two granular gases prepared in the same
macroscopic state, is found to eventually collapse to one of the sides. This
new instability is explained by a simple macroscopic theory which is
furthermore in qualitative agreement with hard disk molecular dynamics.Comment: 7 pages, 5 figure
Parameter estimation for strong phase transitions in supranuclear matter using gravitational-wave astronomy
At supranuclear densities, explored in the core of neutron stars, a strong
phase transition from hadronic matter to more exotic forms of matter might be
present. To test this hypothesis, binary neutron-star mergers offer a unique
possibility to probe matter at densities that we can not create in any existing
terrestrial experiment. In this work, we show that, if present, strong phase
transitions can have a measurable imprint on the binary neutron-star
coalescence and the emitted gravitational-wave signal. We construct a new
parameterization of the supranuclear equation of state that allows us to test
for the existence of a strong phase transition and extract its characteristic
properties purely from the gravitational-wave signal of the inspiraling neutron
stars. We test our approach using a Bayesian inference study simulating 600
signals with three different equations of state and find that for current
gravitational-wave detector networks already twelve events might be sufficient
to verify the presence of a strong phase transition. Finally, we use our
methodology to analyze GW170817 and GW190425, but do not find any indication
that a strong phase transition is present at densities probed during the
inspiral.Comment: 17 pages, 11 figure
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