Low-density Ones Research Articles

Hen harriers and red grouse: economic aspects of red grouse shooting and the implications for moorland conservation

Summary 1. Thirgood & Redpath (2008) propose ways in which red grouse : hen harrier conflicts could be resolved. It has also been suggested that grouse management could accept lower bag sizes (number of birds shot) thus reducing the need for intensive management of predators and habitats. This would allow hen harriers to co‐exist more easily on grouse moors. 2. We compare the bags, costs and incomes from these less intensive forms of grouse shooting with the more intensive driven shooting. 3. Allowing high density grouse moors to decline to low density ones will result in greater loss of income than the corresponding saving of costs. This can result in moor owners abandoning grouse management and thus gamekeepers losing their employment. 4. Losing gamekeepers from the uplands would jeopardize the protection of heather moorland and Special Protection Areas for birds, large areas of which are keepered and which currently support high numbers of breeding waders. 5. Synthesis and applications. We agree with the study by Thirgood & Redpath that consideration of social and economic factors will be needed to resolve conflict but a reduction in management effort from driven to walked‐up shooting is not the answer. A more satisfactory approach to the harrier : grouse conflict could be to try to reduce harrier predation by means of diversionary feeding and to address the problem of the rapid build‐up in harrier numbers by exploring the use of a ceiling on harrier densities.

Confinement transitions in TJ-II under Li-coated wall conditions

This paper presents the latest results on confinement studies in the TJ-II stellarator. The inherently strong plasma–wall interaction of TJ-II has been successfully reduced after lithium coating by vacuum evaporation. Besides H retention and low Z, Li was chosen because there exists a reactor-oriented interest in this element, thus giving special relevance to the investigation of its properties. The Li-coating has led to important changes in plasma performance. Particularly, the effective density limit in NBI plasmas has been extended reaching central values of 8 × 1019 m−3 and Te ≈ 250–300 eV, with peaked density, rather flat Te profiles and higher ion temperatures. Due to the achieved density control, a second type of transition has been added to the low density ones previously observed in ECRH plasmas: higher density transitions characterized by the fall in Hα emission, the onset of steep density gradient and the reduction in the turbulence; which are characteristics of transition to the H mode. Confinement studies in ECH plasmas indicate that lowest order magnetic resonances, even in a low shear environment, locally reduce the effective electron heat diffusivities, while Alfven eigenmodes destabilized in NBI plasmas can influence fast ion confinement.

The effect of honeycomb relative density on its effective in-plane elastic moduli: An experimental study

Honeycombs are discrete materials at the macro-scale level but their mechanical properties need to be calculated as a continuum material in order to simplify their design in engineering applications. The effective mechanical behavior of hexagonal honeycombs was studied by analytical means and correlated with experimental results for aluminum honeycombs. In particular, the effective in-plane elastic moduli of the honeycombs were studied as a function of their relative density. The effect of the bending, shear and axial deformations on various existing beam models was analyzed for both in-plane honeycomb directions. An experimental program was performed with honeycombs of densities ranging from the commercial low-density ones to the solid construction material. It is shown experimentally that the beam models describe well the material response in the direction of the honeycomb double wall. However, it is concluded that the effective elastic moduli for honeycombs with low relative densities are not similar in the two in-plane directions as predicted by previous studies.

Dynamical heterogeneity and diffusion in high-density Al 2O 3·2SiO 2 melts

Dynamical heterogeneity (DH) in high-density Al 2O 3·2SiO 2 melts has been studied in a model containing 3025 atoms via molecular dynamics (MD) simulation and at the fixed density of 4.0 g/cm 3. Non-Gaussian parameter of atomic species in the system has been found and discussed. We found a clear evidence of the existence of DH in high-density Al 2O 3·2SiO 2, which has specific features differed from those observed in the lower-density one. The most mobile and immobile atoms in the system have a tendency to form clusters and temperature dependence of their mean cluster size was found. On the other hand, diffusion constant of atomic species in the system has been calculated at temperatures ranged from 3150 to 7000 K. Calculations show that at relatively not high temperatures, temperature dependence of diffusion constant shows an Arrhenius law and at higher temperatures it shows a power law: D∝( T− T C) γ . Diffusion data of high-density melts have been compared with those for the low-density ones. Diffusion mechanism in the system has been discussed via the temperature dependence of diffusion constant ratio and activation energy. And we found the existence of cooperative diffusion mechanism in the system.

Anisotropic Galactic Outflows and Enrichment of the Intergalactic Medium. I. Monte Carlo Simulations

We combine an analytic model for anisotropic outflows and galaxy formation with numerical simulations of large-scale structure and halo formation to study the impact of galactic outflows on the evolution of the IGM. We have simulated the evolution of a comoving volume (15 Mpc)^3 in the LCDM universe. We follow the formation of 20000-60000 galaxies and simulate the galactic outflows produced by these galaxies, for five outflow opening angles, alpha=60, 90, 120, 150, and 180 degrees (isotropic outflows). Anisotropic outflows follow the path of least resistance and thus travel preferentially into low-density regions, away from cosmological structures where galaxies form. These anisotropic outflows are less likely to overlap with one another, or to hit pre-galactic collapsing halos and strip them of their gas, preventing a galaxy from forming. Going from 180 deg to 60 deg, the number of galaxies that actually form doubles, producing twice as many outflows, and these outflows overlap to a lesser extent. As a result, the metal volume filling factor of the IGM goes from 8% for isotropic outflows up to 28% for anisotropic ones. High density regions are more efficiently enriched than low density ones (~80% compared to ~20% by volume), even though most enriched regions are low densities. Increasing the anisotropy of outflows increases the extent of enrichment at all densities, low and high. This is in part because anisotropic outflows are more numerous. When this effect is factored-out, we find that the probability a galaxy will enrich systems at densities up to 10 rho_mean is higher for increasingly anisotropic outflows. This is an effect of the dynamical evolution of the IGM. Anisotropic outflows expand preferentially into underdense gas, but that gas can later accrete onto overdense structures.

Spatial flow and sedimentation patterns within patches of epibenthic structures: Combining field, flume and modelling experiments

The objectives of the present study were twofold: (1) to identify spatial sedimentation and erosion patterns developing within patches of epibenthic structures (i.e. physical structures that protrude from the sediments, originating either from animals or plants) as a consequence of biophysical interactions; and (2) to assess the relevance of hydrodynamic flume studies for the long-term sediment dynamics in the field. We addressed these objectives by using patches of well-defined artificial structures (bamboo canes) for which we could easily monitor the long-term sediment dynamics in the field, measure the hydrodynamic effects in detail in the flume, and simulate the field and flume set-up with a commercially available hydrodynamic model. Two-year monitoring in the field showed that sedimentation was much larger in the high-density patches than the low-density ones. Within the high-density patches, comparable spatial patterns emerged at different field sites: erosion at the front and the side of the patches, and sedimentation more down-stream within the patches. The low-density patches showed no such patterns, and were generally characterised by some small-scale erosion directly around individual bamboo canes. Sedimentation and erosion in the field was well explained by the patterns in bed shear stress that were derived from our flume measurements. The 3D hydrodynamic modelling facilitated up-scaling of the flume results to the field, but failed to simulate accurately the effects at the leading edge. We conclude that: (A) field observations on sedimentation revealed interesting spatial patterns, but could not elucidate underlying processes; (B) detailed hydrodynamic measurements in a flume can elucidate these underlying processes, provided that appropriate scaling is being used; (C) flume studies are by definition not able to capture all spatial scales that are relevant for estuarine landscape formation and will always cause some flow artefacts; (D) hydrodynamic modelling offers a valuable tool to upscale flume observations, even though present models are not yet capable of fully reproducing all detailed spatial patterns; and (E) spatial heterogeneity is very important when looking at small-scale patches. There is a need for more spatially explicit and scale-dependent knowledge on bio-physical interactions.

Germination rate and seedling vigour of tall fescue as affected by endophyte status and seed density

Forage grass seed quality is influenced by plant genetics as well as seed density, storage conditions, age of seed, and endophyte infection status. We used eight seed lots of tall fescue (three cultivars, with natural endophytes, endophyte-free, or novel endophyte) to test the effect of seed density on germination and seedling vigour. Seed lots were separated into nine density fractions using a cylinder air column. Thousand seed weight values were determined. Three runs of four replications of plots consisting of 25 seeds of each entry were seeded in greenhouse experiments to determine seedling mass at 8 weeks after planting. Early germination counts as well as laboratory germination tests indicated significant differences among weight classes in speed of germination as well as seedling vigour. The lightest fraction of seed clearly contained inferior seed, but higher density seed lots tended to have better germination and seedling vigour than lower density ones. Keywords: seed density, seedling vigour, germination, tall fescue, endophyte

かんらん岩捕獲岩の地質学的側面：日本列島の例

We discuss about geological aspects of deep-seated xenoliths in volcanics from the Japan arcs. We can compare xenoliths in magmas with gravels in rivers. Dams on the rivers are equivalent to magma reservoirs; the former hinder the gravels from downstream transportation as the latter may prevent the deep-seated xenoliths from uprise by accumulation. Rivers with protected banks where gravels are not caught are compared with fixed magmatic conduits where wall rocks are hardly sampled as xenoliths. The magmas that are originated as deep as possible, move upward as fast as possible, and do not form reservoirs are appropriate for providing deep-seated xenoliths as the rivers with deep source and without dams and protected banks are favorable for providing gravels for prospecting geology upstream. Modes of occurrence of deep-seated xenoliths on the Japan arcs suggest us the following. (1) Xenoliths are sorted in an uprising magmatic column; the magma catches deeper-seated, higher-density rocks earlier than shallower-seated, lower-density ones as xenoliths. The proportion of mantle xenoliths dramatically increases upward in stratigraphy of xenolith-producing monogenetic volcanoes. Inversely crustal xenoliths are predominant in the lower eruptives, especially in basal pyroclastics. (2) Rocks are selectively caught as xenoliths by magma. If young, fragile cumulative dikes formed by preceding magmas, subsequent magmas would trace them and do not catch wall rocks, which may be invisible as xenoliths. (3) The upper mantle to lower crust of the SW Japan arc is heterogeneous in thickness of cumulus mantle as well as in development of younger cumulative rocks. The mantle peridotite is cryptically or patently metasomatized by melts for the young cumulates beneath the monogenetic volcano clusters. (4) The upper mantle to lower crust of the NE Japan arc is heterogeneous in hydration. Aqueous fluids would move selectively along cracked or sheared parts to hydrate.

Formation and evolution of elliptical galaxies

We address the problem of the formation and evolution of elliptical galaxies (from dwarf to normal/giant systems). In particular, by means of N-body-tree–SPH simulations, incorporating cooling, star formation, energy feedback and chemical evolution, we intend to explore whether the formation of elliptical galaxies from the monolithic collapse of baryons inside non-rotating, virialized haloes of dark matter leads to results compatible with the main body of observational data on these systems. We show that this scenario can indeed reproduce the basic structural properties of observed elliptical galaxies of different mass. We study the star formation history and the chemical enrichment of the models, showing that the duration, strength and shape of the star formation rate as a function of time depend strongly on the galaxy mass and the initial density. More precisely, massive elliptical galaxies, independent of their initial density, show a single burst of star formation, whereas the low-mass ones have a varied star formation history. It is early and monolithic in the high initial density systems, and irregular and intermittent in the low-density ones. The occurrence of galactic winds is also analysed, and we conclude that in general all galaxies are able to eject part of their gas content into the intergalactic medium. However, the percentage of the ejected material increases with decreasing galaxy mass. Our models are used to interpret the fundamental plane (mass-to-light ratio versus mass relationship), the mass-to-light ratio versus central velocity dispersion, the colour–magnitude relation and the mass–radius relationships of elliptical galaxies from dwarfs to giants. For each relationship in question the agreement between observations and theory is remarkable. Based on this, we endeavour to speculate on a unified scheme for the formation of stellar aggregates going from globular clusters to normal/giant elliptical galaxies in which initial density, type of star formation (single initial episode or recurrent bursts of activity) and galactic winds are the key ingredients. Finally, we draw some conclusions concerning the long-standing question as to whether the hierarchical or the monolithic scheme for the formation of galaxies (ellipticals) ought to be preferred.

Phagocytosis of alveolar macrophages after conagenin injection to rats.

Phagocytic functions of rat alveolar macrophages (AM) following intraperitoneal injection of conagenin (CNG) and of AM sub-populations fractionated by Percoll discontinuous gradient centrifugation were investigated. Phagocytosis of opsonized-sheep red blood cells (SRBC) following in vitro incubation with CNG showed a significant increase in a higher density of AM (fraction IV). In addition, phagocytosis was also increased in lower density ones (fractions I and II) by macrophage-activating factor (MAF) co-cultivation. CNG-injected rats for 5 consecutive days showed a dose-dependent increase in phagocytosis of AM compared to the control rats. Although the distribution of AM sub-population in rats injected CNG was not significantly different compared to the control rats, phagocytosis was significantly increased in AM of a lower density fraction (fraction II). These results suggest that CNG directly increases phagocytosis of AM in a higher density fraction, and indirectly enhances phagocytosis in AM of a lower density fraction via increasing MAF-like material production.

Mucus glycoproteins from pig gastric mucosa: identification ofdifferent mucin populations from the surface epithelium.

Pig gastric mucins were isolated from the surface epithelium of the cardiac region, corpus and antrum using density-gradient centrifugation after extraction in 6 M guanidinium chloride. In CsCl/0.5 M guanidinium chloride, mucins solubilized from the cardiac region appeared as a broad unimodal band at 1.52 g/ml whereas those from the corpus and antrum occurred as high- and low-density populations at 1.50 and 1.45 g/ml respectively. High-iron diamine reacted more strongly with the cardiac mucins and the high-density populations from corpus and antrum than with the two low-density ones. In keeping with this, approx. 60% of the oligosaccharides from the former mucins and 20% from the latter contained sulphate. All surface epithelial cells of the cardiac region stained with high-iron diamine, whereas in the corpus only the epithelium in the bottom of the pits reacted, suggesting that the high-density population from this region originates from these cells. Mucins from all regions were composed of subunits, each containing highly glycosylated domains. The mucins from the cardiac region were larger than those from the corpus and antrum, and reduced subunits as well as high-molecular-mass glycopeptides from the cardiac mucins were larger than the corresponding fragments from the other regions. Ion-exchange HPLC showed that reduced subunits from the cardiac mucins and the high-density populations from the corpus and antrum were more 'acidic' than reduced subunits from the two low-density ones. All mucins contained a 'neutral'fraction, in particular those from the antrum. Pig gastric mucus thus contains a number of distinctly different mucin populations varying in buoyant density, size, 'acidity', glycosylation, sulphation and tissue origin.

Fluid inclusions in granulite-facies metapelites of the Hercynian ancient lower crust of the Serre, Calabria, Southern Italy

Investigations of fluid inclusions in granulitefacies metapelites of southern Calabria enable characterization of the fluid composition of these lower crustal rocks, and constrain the petrologically deduced retrograde P-T path characterized by isothermal uplift prior to isobaric cooling in middle crustal levels. Fluid inclusions in cordierite, garnet and sillimanite have a CO2-rich composition. Inclusions in cordierite rarely contain minor amounts of N2 and H2O, and in garnets some CO2−CH4−N2 inclusions have been analyzed by Raman microprobe. Quartz reveals the most complex fluid melusion compositions (1) CO2-rich, (2) CO2−CH4−N2, (3) CH4−N2, (4) H2O−MgCl2−CaCl2−NaCl, (5) H2O−NaCl and (6) H2O−CO2. The earliest fluid inclusions after peak metamorphism are rich in CO2 with minor amounts of N2 and H2O. An early CO2−(H2O−N2) fluid composition has been confirmed by detection of CO2, H2O and N2 in the channels of the cordierite structure. Most of the early CO2-rich fluid inclusions were modified during the uplift from the lower to the middle crustal level, resulting in a density decrease with CO2 still dominant. The subsequent isobaric cooling led to further modifications of the fluid inclusions. High-density inclusions around implosion textures or scattered amongst lower-density ones must have formed during this cooling episode. Aqueous inclusions in quartz are mostly formed late and are consistent with trapping during retrograde rehydration.

Heterogeneity of fractionated alveolar macrophages in starved rats

Phagocytosis in alveolar macrophages (AM) was enhanced in rats starved for 2 days, but was suppressed by more than 4 day starvation. AM from these rats were separated into four subfractions designated I, II, III and IV by discontinuous Percoll gradient centrifugations. Phagocytosis was greater in higher density fractions (III and IV) than lower density ones (I and II). At 2 days of starvation, the phagocytic activity of higher density fractions was elevated compared to the same fractions from fed rats. Lower density fractions showed high levels of lysosomal enzymes (cathepsin B plus L and β-glucuronidase) compared to higher density ones. These enzymes decreased in parallel with days of starvation. Ultrastructurally, AM of lower density fractions were large and contained more cytoplasmic vacuoles associated with lysosomes than those of higher density, which had numerous microvilli on the cell surface. The fractions of intermediary density overlapped in most of these characteristics. AM fractions in starved rats were heterogeneous with regard to phagocytic activity and lysosomal enzymes. When unfractionated AM of fed rats were incubated with supernatant from alveolar lavage fluid of rats starved for 2 days, their phagocytosis was remarkably enhanced. This result indicated that the lavage fluid of starved rats contained factors enhancing phagocytosis of macrophage and differences of phagocytic activity may reflect the presence of subpopulations among AM from starved rats that undergo different processes of maturation or aging.

Hypertriglyceridemia—Acute Pancreatitis—Ischemic Heart Disease

Hyperlipoproteinemia type V, with serum triglyceride concentrations of about 20 mmol/l, was detected in a pair of monozygotic, 40-year-old twin brothers. One of them had had recurrent attacks of pancreatitis, the other not. The endocrine and exocrine pancreatic functions were apparently normal, supporting that the pancreatitis was secondary to the hypertriglyceridemia. After successful lipid-lowering therapy the attacks of abdominal pain disappeared and remained absent during a 13-year follow-up period. The other twin died of ischemic heart disease nine years after the discovery of his lipid abnormality. The reduction of his lipid levels had been much less successful. His average "atherogenic index" (the ratio of cholesterol in low density to that in high density lipoproteins) was normal but increased to a very high value if cholesterol in very low density lipoproteins was also included together with the low density ones in the numerator. Lipoprotein particles modified in composition may have contributed to an increased uptake through a scavenger pathway and promoted atherosclerosis.

Galaxies from Poisson fluctuations

view Abstract Citations (9) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Galaxies from Poisson fluctuations Epstein, R. I. Abstract The formation of galaxies by the gravitational amplification of small Poisson irregularities is examined. The dynamics of 'isolated' fluctuations is calculated by approximating them by homogeneous spheroids. These results are used, together with the distribution function for protogalactic fluctuations that was derived previously to obtain the mass function of present-day lumps. It is found that the high density systems tend to be spherical and low density ones tend to be oblate and highly flattened. The Poisson representation of the early irregularities yields a good fit to the galaxy mass function if the 'seed' mass at recombination is of the order of 10 million solar masses. The required value of the seed mass is insensitive to the assumed cosmological model. Publication: The Astrophysical Journal Pub Date: June 1984 DOI: 10.1086/162127 Bibcode: 1984ApJ...281..545E Keywords: Galactic Clusters; Galactic Evolution; Mass Distribution; Poisson Density Functions; Approximation; Cosmology; Distribution Functions; Astrophysics full text sources ADS |

Glucuronidation and sulfation of p-nitrophenol in isolated rat hepatocyte subpopulations. Effects of phenobarbital and 3-methylcholanthrene pretreatment

Parenchymal cells, isolated from untreated (control), phenobarbital(PB)- or 3-methylcholanthrene(3-MC)-treated rats, were separated into four subpopulations according to cell density, and glucuronidation and sulfation of p-nitrophenol (PNP) in the hepatocyte subpopulations were investigated. PB enhanced the glucuronidation almost 2-fold but not the sulfation, while 3-MC enhanced both glucuronidation (3-fold) and sulfation (2-fold) in the original cell suspensions. Some gradation trends were found in the conjugation activities among the hepatocyte subpopulations: In the control experiment, the extent of glucuronidation in four subpopulations was virtually the same but sulfation in high-density hepatocytes was slightly higher than in low-density ones. Both glucuronidation and sulfation were higher in low-density hepatocytes from PB-treated rats, though the gradation was very modest. Glucuronidation and sulfation tended to be slightly higher in middle-density hepatocytes in the 3-MC experiment. However, no definite correlation in conjugation activities vs. cell density, like those seen in cytochrome P-450s vs. cell density in the hepatocytes isolated from PB-treated rats, were found in the subpopulations from control or inducer-treated rats. Simultaneous studies on acetylation of p-aminobenzoic acid (PABA) revealed that the activities in the subpopulations were virtually the same and the inducers had little influence on the activity.

Influence of Population Density On the Territorial, Courting and Spawning Behaviour of Male Chromis Cyanea (Pomacentridae)

In a population of C. cyanea on the reef off Curacao, areas with a high and a low population density could be distinguished. Differences in behaviour were found to exist between territorial males of the two areas. During territorial behaviour high density males showed less nest maintenance behaviour and more aggressive behaviour than low density males. During courtship the low density males showed more courting actions than high density males. The latter spent more time on the nest, and succeeded in attracting females in a way different from that of low density males. Also during courtship the high density males showed more aggression than low density ones. The same was true during spawning behaviour. Besides, high density males showed less mating actions than low density ones. The observed differences in behaviour could partly be attributed to differences in external stimulus situation in the two areas. Another part of the behavioural differences, however, were due to differences in the internal state of the males in the two areas. This difference in internal state was attributed to the frequent activation of the behavioural system controlling aggressive actions in high density males. Activation of this system was thought to result in inhibition of the system controlling the nest actions, thus making the nest maintenance and mating actions less likely to occur. The activation of the aggressive system was also thought to affect the courtship in such a way that high density males performed less courting actions. It was shown that the different tactics used in courtship were effective in the area in which they were performed. High density males could rely on staying on the nest waiting for a female to approach them, while low density males had to perform an elaborate courtship performance to lure the females to the nest. To explain this phenomenon it was assumed that the motivation of the female for spawning becomes gradually more favourable through the successive and/or simultaneous influence of bouts of courtship behaviour, irrespective of the courtship being performed by one or by more males. The evolutionary aspects of the observed behavioural differences is discussed. It seems that in the two areas different strategies exist, which enhance the behavioural flexibility of the population. Apparently, in observing the behaviour of C. cyanea, one has to take into account that in different parts of the population different behavioural processes may play a role.

Abnormal Brittleness of Sintered Iron Compacted by Single Pressing

Impact strength of iron compacts, prepared from commercial powders by single compacting under the pressure of 2-9 t/cm2 and by sintering in hydrogen at the temperature range of 1100-1300°C for less than 1 hr, did not simply increase with densification at room temperature, but decreased in the density range around 7 g/cm3.Three different mechanisms for the observed phenomena of abnormal brittleness were considered.First, a shear crack could propagate through large flaky pores formed by the removal of pressed powder lubricants between iron particles. This type of brittleness disappeared after the elimination of flaky pores by sintering at higher temperatures for longer periods.Second, an abnormal growth of ferritic grains could cause an increase of ductile-brittle transition temperature, together with the increase of porosity on grain boundary. This type of brittleness was the same as previously observed by the authors on double pressed materials, and it became remarkable with the progress of sintering.Third, when the ductile-brittle transition occurred above room temperature, the impact strength of high density (above 7 g/cm3) sintered irons could become lower than that of lower density ones at room temperature, because the transition appeared more evidently with densification.