Rapid Increase In Density Research Articles

The Impact of Pollution on Diversity and Density of Benthic Macroinvertebrates in Mountain and Upland Rivers

This article summarizes the studies concerning the impact of pollutants on benthic macroinvertebrate communities in the mountain and upland rivers of southern Poland. The Carpathian Raba River, which in the 1960s retained its natural character and had good water quality, was considered as a reference in terms of benthic macroinvertebrate communities. The other two analyzed rivers were polluted to different degrees. The Carpathian Dunajec River was contaminated mainly by sewage from small towns and treatment plant, while the upland Vistula River mainly by sewage from the Upper Silesian Industrial Region and saline waters from coal mines. In studied ecosystems in response to pollutions, a rapid increase in density of fauna caused mainly by the massive development of Oligochaeta was found. In the mountain river, the impact of contamination on macroinvertebrate diversity was negligible. There, taxa considered as indicators of clean water (Ephemeroptera, Plecoptera, and Trichoptera) were abundant and their diversity was similar to that of an uncontaminated river. In the heavily polluted upland Vistula River, the sites with a muddy bottom were dominated by Oligochaeta (99.4–99.9%), while at sites with stony bottoms, apart from Oligochaeta, there were also Chironomidae, Gastropoda, and Hirudinea. In comparison to the 1950s, all Ephemeroptera, Plecoptera, Odonata, Trichoptera, and Megaloptera were extinct.

Characterizing on the interfacial thermal transport through adsorption clusters and vibrational behaviors

The influencing mechanisms of adsorption and cluster transition on the interfacial heat transfer across the solid-vapor interface are thoroughly examined through molecular dynamics simulations combined with non-equilibrium and statistical thermodynamics analysis. It is found that the adsorption cluster evolutions and vibrational behaviors have notable roles in the variation of interfacial thermal conductance. During the adsorption process, two remarkable different regions are distinguished. In region I, the thermal conductance increases rapidly with the increases of adsorption amount. For the structure of adsorption layer, the empty adsorption sites are occupied and the fractions of small clusters increase sharply. The average atom distance calculated by radial distribution function decreases and the mobility of argon atoms reflected through vibrational density of state at zero frequency is weakened. Both the rapid increase of density near the interface and the enlarged overlap area in phonon spectrum leads to the increase of interfacial thermal conductance. Then, the changing rate of thermal conductance slows down in region II, meanwhile the small-sized clusters are transferred to larger clusters further. The main frequency of adsorbate shifts from 0 to 0.7 THz, which enhances the overlapping of vibrational density of states at the interface. In this region, the matching of the phonon frequencies between the adsorbed cluster and solid surface becomes dominant. Consequently, the thermal conductance enhances further since the empty adsorption sites almost disappear.

Development of a high-speed full digital processing phase detector for interferometry.

This study describes the development of a fully digital-type phase detector for plasma interferometry. This detector functions even in situations in which the phase changes rapidly or the input signal is too small to derive the correct phase shift from the intermediate frequency (IF) signal. The detector directly converts the IF signal waveform of the interferometer to the phase shift signal by means of data processing in a logic circuit. Thus, the phase is derived from the whole waveform of the IF signal. The IF signal of the interferometer is converted to in-phase and quadrature-phase signals by Hilbert transformation, processed by a digital low-pass filter, and converted to polar coordinates by a coordinate rotation digital computer algorithm to obtain the phase shift. A simulation of the high-speed full digital processing phase detector shows that a fringe jump does not occur unless the phase change rate exceeds 0.8 × 106 rad/s. This value is sufficiently large compared to the phase change velocity in rapid density increase resulting from a pellet injection. The phase conversion is simulated using a real IF signal from an interferometer measured with a Heliotron J device. The results show that the phase signal is correctly calculated by the full digital processing method from the IF signal, the phase derivation of which is typically difficult to obtain when using a conventional analog phase detector.

Improving of the mechanical and rheological properties of slip of ceramic

This work is a contribution to the amelioration of the mechanical and rheological properties of a slip of ceramic used in the ceramic fabrication process. A study of characterization of slip of ceramic modified by bentonite has been accomplished chemically, mechanically and rheologically. Chemical analysis showed that the slip modified by bentonite consist essentially of silica with a ratio of (SiO2/Al2O3) average equal to 3.5 and the ratio of clays (Al2O3/SiO2) is relatively stable with increasing percentage of bentonite in the slip, with an average of 0.28. The mechanical and rheological tests were showing that increasing the percentage of bentonite in the base slip caused an increase in the mechanical resistance, the yield stress and rapid increase in density of the slip.

Meso-scale studies on the penetration and retention of diluted bitumen in different types of shorelines, Northern British Columbia, Canada

ABSTRACT 2017-210 Compared to conventional oil, diluted bitumen (dilbit) spills in the environment could be challenging due to the rapid increase in density, viscosity and adhesion properties associated with accelerated weathering. To enhance the response in case of an accidental dilbit spill in the marine environment, a Research & Development program has been developed by the Emergencies Science and Technology Section (ESTS) of Environment and Climate Change Canada (ECCC) as a part of the Federal Government’s Enhancing Marine Safety Strategy. One of the goals of this project was to develop science-based decision support for a dilbit spill to the shorelines of northern British Columbia (BC). In response to this objective, the contractor Coastal and Ocean Resources Inc. has conducted a meso-scale Diluted Bitumen Sediment Interactions Experiments (Bit_EX) to evaluate the potential of penetration and retention of dilbit in different types of sediments. In total, two dilbits, Access Western Blend (AWB) and Cold Lake Blend (CLB) at three weathered states (0%, 17% and 26% mass loss), were tested against seven types of sediments (from coarse sand to very large pebble). The adhesion of dilbit on bare cobbles and on cobbles covered with barnacles and seaweed (fucus) was also tested for different time of exposure. Results showed that unweathered (or fresh) dilbit has its maximum penetration and retention in coarse sand or granule whereas moderately weathered dilbit has maximum penetration and retention in small pebbles or larger sediment sizes. Heavily weathered dilbits have very limited penetration in finer sediments but are expected to penetrate and have high retention in permeable coarse sediments. Moreover, we have observed that dilbit adherence could be enhanced with longer drying time. In northern BC, the bedrock platforms with thin overlays of various types of sediment, from sand to boulders, are common and presents a complex case for treatment. Because dilbit characteristics change rapidly, early SCAT survey data combined with rapid decision and operational response in the initial stages of the spill could reduce dilbit retention and adhesion. The Bit_EX also suggests that existing techniques for protection and cleanup of conventional oil on shorelines could be applicable or can be adjusted for dilbit spills. This experiment provides information suitable to a first response guide for protecting and cleaning shorelines in case of bitumen spills in northern BC.

Spectrally smooth X-ray source produced by laser direct driven DT implosion target on SG-Ⅲ laser facility

Spectrally smooth X-ray sources can be used in point projection radiography and absorption spectrometry diagnostics of dense plasmas. But conventionally they are end at about 3.5 keV, which can only be used to diagnose materials up to Z=18. Spectrally smooth X-ray sources above 3.5 keV are needed to study higher-Z materials. Bremsstrahlung radiation from a laser driven implosion target can produce a small size, short duration and spectrally smooth X-ray source in the range of 1-100 keV. They have been successfully applied in the investigations of middle-Z materials in the 3-7 keV X-ray range. Despite much interest for backlit X-ray studies of middle- and high-Z dense materials, research on implosion X-ray sources are scarce. Characterization of the implosion X-ray source is needed to understand and improve its performance.To provide a physical basis for optimization, the properties of the deuterium-tritium (DT) implosion target X-ray source driven by 30-180 kJ laser pulses were explored using a radiation hydrodynamics code.We focus on laser pulse energies of 30-180 kJ at 351 nm wavelength to match the range of the OMEGA laser on the low end and the SG-Ⅲ laser on the high end. The laser pulse parameters are scaled with the target size in identical fashion to that of the OMEGA laser and the ignition designs of the National Ignition Facility to maintain the same irradiance on the surface of the capsule.The temporal and spatial evolution of the implosion targets was calculated using Multi-1D, a one-dimensional radiation hydrodynamics code. The emergent X-ray spectrum is calculated by post-processing from the time histories of the temperature and density profiles output by the Multi-1D code. We adjusted the laser absorption fraction to ensure neutron yield in accordance with OMEGA's 1D simulation results.It shows that the rapid increase of density and temperature at stagnation time develops a 150 ps point X-ray flash with approximately 100 μm size. The dominant X-ray emission comes from the inner layer of the dense compressed shell, which should be the focus of future efforts to improve the X-ray emission. Softer X-rays below 30 keV carry most of the energy due to the exponentially decaying spectral profile of implosion X-ray source. Opacity of the dense compressed shell plasma can markedly reduce the very softer X-ray emission of 1-3 keV. DT fusion reactions can enhance the share of harder X-rays above 30 keV greatly, while show negligible effect on the brightness of the implosion X-ray source. Thus higher-Z plastic target or glass target may be a better choice in generating the implosion X-ray source.

Hot pressed SiC ceramics employing polymer-derived SiBCN as sintering aid

SiC ceramics were densified with 10wt.% polymer-derived SiBCN additives by hot-pressing under a load of 40MPa at 1850°C for 90min in a vacuum environment. Polyborosilazane was chosen as the SiBCN precursor and pyrolyzed at 1000°C before use. The obvious densification process began at about 1700°C during the sintering. The densification mechanism was different from the SiC ceramics densified by traditional sintering aids. When the temperature was above 1700°C, particle rearrangement was accelerated because deformation and/or viscous flow of the SiBCN occurred under the external pressure. This procedure resulted in rapid increase of density. After particle rearrangement, B and C elements and nano SiC grains separating out from the SiBCN material led to SiC grain growth and further densification. The bending strength and Vickers hardness of the product were 562±36MPa and 22.5GPa at room temperature.

RAPID EVOLUTION OF THE SOLAR ATMOSPHERE DURING THE IMPULSIVE PHASE OF A MICROFLARE OBSERVED WITH THE EXTREME-ULTRAVIOLET IMAGING SPECTROMETER ABOARDHINODE: HINTS OF CHROMOSPHERIC MAGNETIC RECONNECTION

We obtained rapid cadence (11.2 s) EUV stare spectra of a solar microflare with the Extreme-ultraviolet Imaging Spectrometer aboard Hinode. The intensities of lines formed at temperatures too cool to be found in the corona brightened by factors around 16 early during this event, indicating that we observed a site of energy deposition in the chromosphere. We derive the density evolution of the flare plasma at temperature around 2 MK from the intensity ratio of Fe XIV lines at 264.789 A and 274.204 A. From both lines we removed the bright pre-flare quiescent emission, and from 274.204 we removed the blended emission of Si VII λ274.180 based on the Si VII λ274.180/275.361 intensity ratio, which varies only slightly with density. In this way the flare electron density is derived with emission from only the flare plasma. The density increased by an order of magnitude from its pre-flare quiescent average of (3.43 ± 0.19) × 109 cm–3 to its maximum impulsive phase value of (3.04 ± 0.57) × 1010 cm–3 in 2 minutes. The fact that this rapid increase in density is not accompanied by systematic, large upward velocities indicates that the density increase is not due to the filling of loops with evaporated chromospheric material, but rather due to material being directly heated in the chromosphere, likely by magnetic reconnection. The density increase may be due to a progression of reconnection sites to greater depths in the chromosphere, where it has access to larger densities, or it may be due to compression of 2 MK plasma by the 10 MK plasma as it attempts to expand against the high-density chromospheric plasma.

Loss of density-dependence and incomplete control by dominant breeders in a territorial species with density outbreaks

BackgroundA territory as a prerequisite for breeding limits the maximum number of breeders in a given area, and thus lowers the proportion of breeders if population size increases. However, some territorially breeding animals can have dramatic density fluctuations and little is known about the change from density-dependent processes to density-independence of breeding during a population increase or an outbreak. We suggest that territoriality, breeding suppression and its break-down can be understood with an incomplete-control model, developed for social breeders and social suppression.ResultsWe studied density dependence in an arvicoline species, the bank vole, known as a territorial breeder with cyclic and non-cyclic density fluctuations and periodically high densities in different parts of its range. Our long-term data base from 38 experimental populations in large enclosures in boreal grassland confirms that breeding rates are density-regulated at moderate densities, probably by social suppression of subordinate potential breeders. We conducted an experiment, were we doubled and tripled this moderate density under otherwise the same conditions and measured space use, mortality, reproduction and faecal stress hormone levels (FGM) of adult females. We found that mortality did not differ among the densities, but the regulation of the breeding rate broke down: at double and triple densities all females were breeding, while at the low density the breeding rate was regulated as observed before. Spatial overlap among females increased with density, while a minimum territory size was maintained. Mean stress hormone levels were higher in double and triple densities than at moderate density.ConclusionsAt low and moderate densities, breeding suppression by the dominant breeders, But above a density-threshold (similar to a competition point), the dominance of breeders could not be sustained (incomplete control). In our experiment, this point was reached after territories could not shrink any further, while the number of intruders continued to increase with increasing density. Probably suppression becomes too costly for the dominants, and increasing number of other breeders reduces the effectiveness of threats. In wild populations, crossing this threshold would allow for a rapid density increase or population outbreaks, enabling territorial species to escape density-dependency.

Numerical simulations for cold layer formation in an inverse Z-pinch magnetized target fusion system

One-dimensional magnetohydrodynamic simulations have been performed to study cold layer formation in a magnetized target fusion system with an inverse Z-pinch target plasma. Three phases of cold layer evolution has been identified. During the early compression phase, when liner velocities were not high, formation of a “classical” cold layer is observed, with monotonically increasing plasma densities and decreasing temperatures as the liner is approached. During the main compression phase, lasting until close to peak compression, magnetic flux leakage from the plasma to the liner is not important. The cold layer is then characterized by monotonically decreasing plasma temperature, density, and thermal conductivity. This has practical significance, since it would tend to reduce thermal losses to the liner. During the late compression and burn phases, magnetic flux leakage into the liner becomes important. This phase is characterized by a rapid increase in density and a rapid decrease in magnetic field and temperature toward the liner. This yields significantly higher values of thermal conductivity than in the bulk plasma, leading to enhanced thermal losses. During the first two phases, the entire plasma is magnetically confined. During the last phase, the cold layer changes to a wall-confined mode, while the bulk plasma continues to be magnetically confined. This is a major difference from earlier assumptions about wall confinement of such plasmas. These results show that the Kadomtsev stability parameter exceeds unity in the cold layer during the second and third phases, which may be an indication of instability. The choice of the transport model has a significant effect upon plasma evolution and the plasma lifetime. Classical transport yields plasma density levels near the liner that are significantly higher, sometimes by orders of magnitude, than those yielded by Bohm transport. During the main compression phase, Bohm diffusivity yields a lower lifetime, as expected. During the early compression phase, however, the classical lifetime is unexpectedly below the Bohm value. A physical explanation has been provided for these trends.

Evidence-based culling of a facultative predator: Efficacy and efficiency components

Human activities have greatly modified predator–prey dynamics within seabird communities by favouring a rapid increase in density of large predatory gulls. To counteract such a subsidized growth, conservation agencies perform massive random culling programs, which generally fail to restore the original predator–prey relationship. We used long-term individual-based information to evaluate the effects of a selective culling of a top seabird predator, the yellow-legged gull ( Larus michahellis), on the predatory pressure, survival and reproductive success probabilities of a secondary prey, the vulnerable European storm-petrel ( Hydrobates pelagicus). The selective removal of only 16 gulls in 3 years led to a reduction of ca. 65% in the number of petrels killed, and to a relative increase in their survival and breeding success probabilities of 16% and 23%, respectively. Our results show that only a few specialised predators were responsible for the bulk of the impact on a secondary prey and that the removal of those specialised individuals was an effective and efficient way to improve prey demographic parameters.

Numerical Model of an Argon Atmospheric Pressure RF Discharge

Radio-frequency discharges are known to operate in two different regimes. The alpha regime of low current density and the gamma regime with higher current density. Our recent simulation results suggest that the formation of filaments observed in an atmospheric pressure argon discharge under RF excitation could be triggered by the regime transition alphararrgamma. A unidimensional fluid model taking into account the external circuit shows that above 120 mA/cm2 , the differential conductivity of the discharge becomes negative with a rapid increase in density which can lead to the formation of filaments. As the transition to the gamma regime is due to secondary electrons, this threshold value depends on the secondary emission coefficient. In the gamma regime, the instantaneous cathode is sustained by secondary electron emission, which drastically changes the behavior of the discharge. In this paper, we present a numerical analysis of the transition between the two regimes and discuss how this could result in the filamentary mode observed in argon RF discharges.

Quenching of steam-charged pumice: Implications for submarine pyroclastic volcanism

Huge quantities of silicic pumice have been deposited in intra-oceanic convergent margin settings throughout Earth's history. The association of submarine silicic calderas with thick proximal accumulations of pumice lapilli suggests that these pyroclasts were deposited as a direct result of submarine eruptions. Yet when first erupted, these highly vesicular, gas-filled clasts had densities significantly less than seawater. Experiments carried out 1-atm on heated pumice samples whose vesicles were charged with steam, the dominant component of magmatic volatiles show that buoyancy of freshly erupted submarine pumice is transient. Upon quenching, the phase change of steam-to-liquid water creates strong negative pore pressures within the pumice vesicles that accelerate the absorption of surrounding water, generating high-density pumice and promoting rapid clast sinking. Variations in the physical properties of steam with temperature and pressure have important implications for submarine pyroclastic eruptions. Firstly, highly vesicular pumice can be deposited on the seafloor at temperatures elevated significantly above ambient if they are erupted at sufficient depths to remain wholly submarine (> ∼ 200 m) and either the fluid in which they cool contains heated water and/or they only absorb sufficient water to sink. Secondly, the rapid increase in density of the eruption column caused by condensation and the transition from buoyant (gas-filled) to denser (water-saturated) pumice lapilli, together with turbulent mixing with the surrounding seawater favour collapse and transport of pyroclasts in water-supported gravity currents. Finally, this mixing of the ejecta with seawater and the ease of water ingestion into permeable pumice clasts suggest that water-supported transport mechanisms can operate as primary dispersal processes in explosive submarine eruptions.

Temperature-Mediated Relationship Between Western Flower Thrips (Thysanoptera: Thripidae) and Chrysanthemum

Modeling the effect of temperature on the sustainability of insect-plant interactions requires assessment of both insect and plant performance. We examined the effect of temperature on western flower thrips, Frankliniella occidentalis (Pergande), a generalist herbivore with a high reproductive rate, and chrysanthemum inflorescences, a high quality but relatively fixed, ephemeral resource for thrips population growth. We hypothesized that different thrips versus plant responses to temperature result in significant statistical interaction of temperature with thrips abundance and flower damage attributes over time. Experiments were conducted at five temperatures between 20.7 and 35.3 degrees C, with thrips infestation and time after infestation as main effects. Only minor, uncontrolled variations in relative humidity and light intensity may otherwise have influenced the results. High temperatures lead to an initially rapid increase in density of thrips followed by abrupt declines in abundance. The rate of floral senescence increased with temperature and thrips infestation, as indicated by a reduced fresh biomass and greater leaching of yellow pigments. Multiple regression indicated that indices of plant damage responded more directly to thrips density at low than high temperature, supporting the conclusion that temperature affected the outcome beyond what was predictable simply from differential plant and insect optima. The relative intensity of damage caused by individual thrips decreased with increasing temperature, likely caused by thrips competition and reduced survival, growth, and fecundity on depleted inflorescences. Reduced per capita damage at high temperature may be common in insects exploiting fixed plant resources that exhibit an accelerated rate of deterioration at high temperatures.

Study of Edge Transport Barrier Formation on CHS Plasma

An edge transport barrier (ETB) similar to the tokamak H-mode has been observed for beam-heated plasma with two co-injected Neutral Beam Injectors (NBIs) in CHS. The Hα emission showed a clear spontaneous drop followed by an increase of line-averaged electron density at the L-H transition. Stored energy increased by ˜ 40% with H-factor improvement up to ˜ 30% compared to the international stellarator scaling (ISS04v03). A rapid density increase in the edge region to two-times level of the L-mode was observed to accompany a ˜ 15% increase in the density gradient. An ETB was formed when the plasma density exceeded the lower density limit by ˜ 1.5 × 1013 cm-3 and the total NBI power exceeds the threshold level (Pdeposit / ne ˜ 200 × 10-13 kW/cm-3 at BT = 0.95 T, Rax = 92.1 cm, where Pdeposit is the deposited NBI power, ne is electron density, BT is troidal magnetic field strength and Rax is location of magnetic axis). The power threshold increased with the magnetic field strength, as in tokamak scaling, and depends on the magnetic field configuration of the helical plasma.

해충관리 수준이 다른 이앙재배 논에서의 거미의 발생과 개체군 동태

본 연구는 1996년부터 1998년까지 경기도 화성시 발안 지역의 이앙재배한 논에서 발생하는 거미의 개체군 동태 및 군집자료를 바탕으로 관행의 살충제 살포가 거미군집에 미치는 영향을 분석하기 위해 수행되었다. 3년간 조사에서 조사 포장들에서 거미군집은 연간 변이가 적은 안정된 발생을 보였으며, 발생밀도에서 천적군의 90% 이상을 차지하는 최대 우점군이었다. 이 지역의 벼 생육기간동안 단위면적당<TEX>$(0.25m^2)$</TEX> 평균 거미밀도는 약 10마리 정도였으며, 늑대 거미과(Lycosidae), 갈거미과(Tetragnathidae), 접시거미과(Linyphiidae)가 우점하였다. 거미군집의 밀도는 본답 초기에 벼의 이앙과 함께 이입으로 인해 형성되기 시작하여 중기부터 급격한 밀도 증가를 보이며, 후기에 최고밀도를 유지하다가 수확시기에 밀도가 감소하는 패턴을 가졌다. 특히, 비래 해충의 발생이 적었던 해에는 관행적인 살충제 살포에 의한 거미군집의 교란 효과가 적게 나타났다. 우점종인 황산적거미와 턱거미는 다소 다른 개체군 동태를 가졌는데, 황산적거미는 7월 중순부터 밀도가 급격히 증가하고, 후기에는 성체보다는 유체들의 발생비율이 높았던 반면, 턱거미는 8월 말부터 밀도가 급격히 증가하였고, 후기에 성체형태로 대부분 발견되었다. This study was conducted to evaluate the effect of the conventional pesticide application system on the rice spider community based on the quantitative investigation of arthropod community in the rice fields in Saran area, Hwasung-si, Kyeonggi-do from 1996 to 1998. Spiders were the highest dominant group comprising over 90% of all natural enemies in their density, and showed very stable yearly occurrence. In these fiekds the mean density of spiders was about 10 individuals/<TEX>$0.25m^2$</TEX> during the rice growing season, and three families including Lycosidae, Tetragnathidae and Linyphiidae were very abundant. The colonization of spiders occurred in early season and they showed rapid density increase in mid-season. They maintained the highest density to the late season and their density decreased at harvest season. In the years of the low rice pest occurrence, the disturbance effect on spider community by pesticides were less. Two dominant species, Pirata subpiraticus and Pachygnatha clerki, had different population dynamics; Pirata subpiraticus showed the rapid density increase in the mid-July, and most of them remained immature stages, however, in the case of Pachygnaths clerki population, they rapidly increased in the late August and most of them remained adult stage during the late growing season.

The tumour necrosis factor-alpha inhibitor adalimumab rapidly reverses the decrease in epidermal Langerhans cell density in psoriatic plaques

The pathophysiology of psoriasis is poorly understood, and the mechanism of action of biological agents interfering with tumour necrosis factor (TNF)-alpha that improve psoriatic plaques is completely unknown. To begin to unravel the mechanism of action, cellular changes occurring in plaques following administration of adalimumab, a humanized monoclonal antibody against TNF-alpha, were investigated. Thirteen different patients underwent sequential biopsies as part of a clinical trial. Each biopsy was immunostained and evaluated to calculate the relative density of epidermal Langerhans cells (LCs) before and after treatment (days 2, 7, 28, 84). To explore the basis for reduced epidermal LC densities in plaques, a SCID-Hu animal model was utilized. Acute psoriatic lesions were created within 2 weeks by injection of superantigen-activated CD4+ T cells into engrafted symptomless skin. Compared with symptomless skin, untreated plaques had a significantly reduced density of epidermal LCs. There was a rapid increase in density of epidermal LCs in plaques following treatment with adalimumab beginning as early as day 7. The paucity of epidermal LCs in plaques was contrasted to the prominent density of LCs in other skin disorders with chronic inflammation and alterations in keratinization, including lichen planus and inflamed seborrhoeic keratosis. Rapid creation of plaques using the SCID-Hu model was accompanied by loss of epidermal LCs, indicating that diminished LC density occurs at an early stage of lesion formation. These data shed light on a new immunopathological perspective highlighting a rapid loss of epidermal LCs in acute psoriatic lesions, with sustained decreased density of LCs in chronic plaques. Furthermore, an unexpected insight into the mechanism of action was uncovered for adalimumab, in which rapid restoration of epidermal LC density was observed.

Formation of a dense water cascade in the marginal ice zone in the Barents Sea

In this paper, we examine the origin of a dense water cascade in the marginal ice zone west off the Novaya Zemlya Archipelago in the Barents Sea. We specifically consider how ice advection and melting contribute to the formation of density gradients favourable for cascading. The study is based on three hydrographic surveys taken in December 1987 by Russian research vessels, composite ice maps and meteorological records. A bulk numerical model is applied in order to quantify the dominant physical processes responsible for re-shaping the thermohaline structure, from a state that opposes cascading to one that enhances it. The overall effect of these processes significantly varies depending on the distance from the shore. The most intensive ice production and rapid density increase occurred in the shallow waters, where the salinity increase accounted for almost 90% of the total density increase. The transitional zone, covering the outer shelf and slope waters, is subject to strong freshening by melting ice, which is transported from the production zone. This effect diminishes in the deep water, where the amount of imported ice is small. The opposing trends in salinity in the production and transitional zones caused by the joint effects of freezing/melting and ice mobility play a crucial role in providing the necessary conditions for the onset of cascading. Without ice advection and melting, the density contrast between the shallow and deeper waters at the shelf break would have been −0.10 (kg/m 3), which would inhibit the formation of dense water cascade. The difference in density fluxes on both sides of the front was 2.1×10 −5 (kg/m 2 s), which is comparable with average flux over Arctic polynyas, and resulted in a cross-frontal density difference of 0.06 kg/m 3, which favours dense water cascading.

Double-peak specific heat feature in frustrated antiferromagnetic clusters

We study the nature of the double-peak specific heat structure in kagome clusters. That containing 12 spins is considered thoroughly by numerical diagonalization. Simple models are proposed revealing the low-$T$ peak nature at $T_l<\Delta$ ($\Delta$ is the spin gap) in this case and in those of larger clusters studied so far. We show that the rapid increase in density of states just above the spin gap gives rise to this peak. These models establish the reason for the weak magnetic field sensitivity of the low-$T$ peak. Our discussion could be appropriate for other frustrated antiferromagnetic systems too.

Localization of charge carriers in materials with high polaron concentration

The influence of polaron concentration on the type of transition from band to activate conductivity has been investigated. For a single polaron in the crystal lattice or for material with polaron concentration higher than the percolation threshold, such a transition is continuous, in accordance with theory. However, for intermediate cases this process becomes step-like, because the rapid increase of density of states at Fermi level leads to a change of polaron characteristics. These suppositions are illustrated by experimental results (XPS-spectra, crystal structure analysis, DC conductivity) for intercalation compounds based on titanium dichalcogenides.