Higher Average Density Research Articles

Energy Harvesting with a Bimorph Type Piezoelectric Diaphragm Multilayer Structure and Mechanically Induced Pre‐stress

AbstractThe energy harvester is constructed from four circular bimorph type piezoelectric diaphragms which are stacked and pre‐stressed with a mechanical spring. Mechanical pre‐stress keeps the voltage cancellation at a minimum between the bimorph layers and enhances the physical compression distance. This results in much higher power densities than previously reported for low‐frequency piezoelectric energy harvesting applications. The voltage output at ∼1 Hz compression frequency, which closely corresponds to the pace of human walking, gives an average power output of 11.30 mW, a very high average power density of 10.55 mW cm−3 for the piezoelectric material. The results show that bimorph type stacked and pre‐stressed piezoelectric diaphragms can provide a sufficiently compact and efficient structure to harvest useful amounts of energy; enough, for example, to power and recharge various portable devices and sensors in future applications.

Effect of Structure of Internal Waves on Energy Transfer and Flow Control Between South and Middle Basins of Caspian Sea

In this study, role of internal waves in controlling stratified exchange flows between south and middle basins of Caspian Sea and energy transfer have been studied. The studies have been conducted based on field and theoretical studies based on numerical calculations. In this investigation, Caspian Sea has been considered as stratified and Boussinesq approximation has been considered. In equations governing the movement, cohesion and compressibility have been neglected. In the field studies, investigation of density profiles indicate signs of stratified structure which so far has been attributed to dual distribution convection phenomenon, but by considering density ratio profile and values of density ratio which are mostly negative numbers, the factor causing stratified structure of Caspian Sea can be attributed to existence of internal waves. Density field in these two basins indicate that the middle basin has higher average density compared to the south basin, this fact can cause creation of a gravity exchange flow. This exchange flow causes creation of internal waves in this sea that can have a modal structure towards vertical direction. In theoretical studies, the two middle and south basins of Caspian Sea are networked in two dimension x-z systems and equations governing movement are solved through a numerical method by using finite difference method and the vertical velocity values obtained in 290 points of the network was almost 10<sup>-6</sup> to 10<sup>-4</sup> m/s, meaning that vertical movements are much smaller. Values obtained for horizontal velocity are almost 10<sup>-3</sup> to 10<sup>-1</sup> m/s. Vertical and horizontal velocity profiles obtained from solution of these equations and also density profile obtained in four integration periods indicate that as a result of passage of gravity flow between the two basins, density in various points of the two basins change. The structure created from internal waves on the crest causes creation of shear strata observed. This structure can be effective in exchange of the two basins. Therefore, in transfer and energy conversion, identification of the created strata is of a high importance.

Central Molecular Zone of the Milky Way: Star Formation in an extreme Environment

AbstractThe Central Molecular Zone (CMZ; inner ~100 pc) hosts some of the most dense and massive molecular clouds of the Milky Way. These clouds might serve as local templates for dense clouds seen in nearby starburst galaxies or in the early universe. The clouds have a striking feature: they form stars at a very slow pace, considering their mass and high average density. Here we use interferometer data from ALMA and the SMA to show that this slow star formation is a consequence of the cloud density structure: CMZ clouds have a very flat density structure. They might, for example, exceed the average density of the Orion A molecular cloud by an order of magnitude on spatial scales ~5 pc, but CMZ “cores” of ~0.1 pc radius have masses and densities lower than what is found in the Orion KL region. This absence of highest–density gas probably explains the suppression of star formation. The clouds are relatively turbulent, and ALMA observations of H2CO and SiO indicate that the turbulence is induced by high–velocity shocks. We speculate that these shocks might prevent the formation of high–mass cores. It has been argued that the state of CMZ clouds depends on their position along the orbit around Sgr A*. Our incomplete data indicate no evolution in the density structure, and only a modest evolution in star formation activity per unit mass.

Substrate choice by the alien snail Ferrissia fragilis (Gastropoda: Planorbidae) in an industrial area: A case study in a forest pond (Southern Poland)

AbstractThe aims of this study were to determine the substrate choice by the alien snail Ferrissia fragilis (Tryon, 1863) (Phragmites australis and Typha latifolia remains, Nuphar lutea floating leaves and leaf deposit) as well as the environmental factors that influence the occurrence of this species. From 9 (T. latifolia and P. australis) to 11 (leaf deposit) snail species occurred on each type of substrate. F. fragilis belonged to the eudominants on most of the substrate types. This species reached its highest average density on floating N. lutea leaves (271 ind. m−2) and the lowest was on P. australis (60 ind. m−2). It occurred in different periods during the snail collection: in the initial study period on the floating N. lutea leaves (May) and on P. australis in the final period of the study (September). In July, we found a few specimens in the postseptal form on T. latifolia remains. The results of RDA analysis confirm the association between F. fragilis and T. latifolia as well as with floating N. lutea leaves. F. fragilis occurs at sites that have a higher content of calcium and iron in the water. Alien species more increasingly appear in disturbed anthropogenic water-bodies. An important vector in the dispersion of F. fragilis was probably the water birds or the economic activities that are related with the use of this forest pond. Studies on the occurrence of alien species contribute important data on the activities that are taken to preserve the biodiversity of freshwater environments

Enhancing Quality of Desert Tortoise Habitat: Augmenting Native Forage and Cover Plants

Abstract Vegetation in habitat of the federally listed desert tortoise Gopherus agassizii in the Mojave and western Sonoran Desert is now partly or mostly dominated by nonnative annual plants. To improve forage quality and augment availability of perennial cover plants, we tested seeding (pelletized or bare seeding), watering, and fencing for increasing a native annual forage species (desert plantain Plantago ovata), a perennial forage species (desert globemallow Sphaeralcea ambigua), and two shrub species (cheesebush Hymenoclea salsola and winterfat Krascheninnikovia lanata) that provide cover in desert tortoise habitat of southern Nevada. Treatments were ineffective at establishing the perennial species, even though greenhouse assays confirmed that some bare and pelletized seeds were germinable. In contrast, pelletized seeding quadrupled the density of desert plantain compared with not seeding or seeding untreated seed by the end of the first year (autumn 2013). Fencing tripled density of desert plantain to 17 plants/m2. Pelletized seeding plus fencing produced a desert plantain density of 39 plants/m2, the highest average density among all treatment combinations. The positive effect of fencing persisted until at least the second year after treatment (autumn 2014). Augmenting native annual forage plants favored by desert tortoises is feasible.

Properties of modified dry masonry mixtures for effective masonry units

The paper is devoted to the problem of the development of dry light-weight mixtures with hollow ceramics microspheres (CMS) for masonry works. For the one-layer fencing structures including effective masonry units, the use of "warm" masonry mortars is necessary. The used light-weight masonry mortars do not provide the brand strength and thermal uniformity of the fencing structures because of high average density. The CMS are effective light-weight aggregate for such mortars. The influence of the dosage of CMS on the physics- and-mechanics parameters and the technological properties of the masonry mortars has been studied. The optimal mixture compositions have been obtained and their main properties have been determined. The influence of an air-entraining admixture and redispersible polymer powders on the average density and physics-and-mechanics parameters of the masonry mortars have been studied. The optimal compositions of light-weight dry masonry mixtures with CMS have been suggested. It has been established that the mortars, obtained from such mixtures, have the requisite average density, the water retention capacity more than 95 %, high homogeneity and high strength characteristics. The application of the proposed mixtures enables to reduce the construction material costs and to improve the energy efficiency of the fencing structures.

CHARACTERIZING THE YOUNGESTHERSCHEL-DETECTED PROTOSTARS. I. ENVELOPE STRUCTURE REVEALED BY CARMA DUST CONTINUUM OBSERVATIONS

We present CARMA 2.9 mm dust continuum emission observations of a sample of 14 Herschel-detected Class 0 protostars in the Orion A and B molecular clouds, drawn from the PACS Bright Red Sources (PBRS) sample (Stutz et al.). These objects are characterized by very red 24 \micron\ to 70 \micron\ colors and prominent submillimeter emission, suggesting that they are very young Class 0 protostars embedded in dense envelopes. We detect all of the PBRS in 2.9 mm continuum emission and emission from 4 protostars and 1 starless core in the fields toward the PBRS; we also report 1 new PBRS source. The ratio of 2.9 mm luminosity to bolometric luminosity is higher by a factor of $\sim$5 on average, compared to other well-studied protostars in the Perseus and Ophiuchus clouds. The 2.9 mm visibility amplitudes for 6 of the 14 PBRS are very flat as a function of uv-distance, with more than 50\% of the source emission arising from radii $<$ 1500 AU. These flat visibility amplitudes are most consistent with spherically symmetric envelope density profiles with $\rho$~$\propto$~R$^{-2.5}$. Alternatively, there could be a massive unresolved structure like a disk or a high-density inner envelope departing from a smooth power-law. The large amount of mass on scales $<$ 1500 AU (implying high average central densities) leads us to suggest that that the PBRS with flat visibility amplitude profiles are the youngest PBRS and may be undergoing a brief phase of high mass infall/accretion and are possibly among the youngest Class 0 protostars. The PBRS with more rapidly declining visibility amplitudes still have large envelope masses, but could be slightly more evolved.

Vertical distribution of zooplankton in Lake Nasser

The composition and distribution of zooplankton communities in three depths (surface, 10–5m and 20–15m depths) along main channel of Lake Nasser were studied in 2013. The density of total zooplankton was increased to maximum during winter and autumn at surface water (39,362 and 63,100Ind.m−3, respectively) and gradually decreased with depth until attaining the lowest average density at 20–15m (12,460 and 8976Ind.m−3). During spring and summer, zooplankton was irregularly distributed through the water profile, where the highest average density was recorded at 10–5m depth (66,007 and 66,734Ind.m−3). Copepoda was the dominant zooplankton group at all depths, it represented about 70–76.2% of the total zooplankton count. Cladocera formed about 13.4%, 14.5% and 11% of total zooplankton density for surface, 10–5m and 20–15m depth. It was decreased with increasing depth during winter and autumn; however it attained its maximum density at 10–5m depth during spring and summer. Rotifera average density decreased with increasing depth. The dominant zooplankton species inhabiting Lake Nasser were strongly temperature-dependent. The study recommends the introduction of some pelagic fish species to consume the high persistence of zooplankton community at the upper 10meters of water column.

Evaluation of Suitability of Some Selected Rocks for Dimension Stone Quarry in Akure, Ondo State, Nigeria

The evaluation ofrock suitability for dimension stone quarry has been a thing of concern to the dimension stone industries. So, three granite rocks were selected in various locations in Akure, Ondo State, Nigeria. The locations are Iloyin, Oba‐ile and Apatapiti and on these outcrops,in‐situ tests were carried out on the outcrops and irregular rock samples were collected for laboratory tests. Schmidt hammer test and Scan line mapping for discontinuities analysis were done on site while sample test for density, specific gravity, average water absorption, point load strength and slake durability were done in the laboratory. The Apatapiti outcrop hasthe highest average density (3.12g/cm 3 ), specific gravity (2.822) and water absorption value (0.84%), while the Iloyin outcrop exhibits the highest average durability (97.88%) and point load strength (5.79MPa), the Oba‐Ileoutcrop have the highest compressive strength (190MPa)and average Schmidt hammer hardness value (47.0). The three outcrops volumetric joint count, Jv estimated gave medium block sizes but in the case of block quality of the rockssubjected to evaluation Iloyin happens to be of poor quality while Oba‐Ileand Apatapiti outcrop have prospect ofproducing fair quality block. With the information fromthe assessment of block size, block quality and mechanical and physical properties for the rocks consideredin this paper work, it was observed that these three selected outcrop are not good for dimension stone quarry but can be quarried as aggregate stone for construction purposes.

High-power InGaAs/GaAs quantum-well laser with enhanced broad spectrum of stimulated emission

We report the demonstration of an InGaAs/GaAs quantum well (QW) broadband stimulated emission laser with a structure that integrated a GaAs tunnel junction with two QW active regions. The laser exhibits ultrabroad lasing spectral coverage of ∼51 nm at a center wavelength of 1060 nm with a total emission power of 790 mW, corresponding to a high average spectral power density of 15.5 mW/nm, under pulsed current conditions. Compared to traditional lasers, this laser with an asymmetric separate-confinement heterostructure shows broader lasing bandwidth and higher spectral power density.

6.8 W all-fiber supercontinuum source at 1.9–2.5 μm

We report a simple method of generating a spectrally flat and high average power spectral density (up to 14 mW/nm) optical supercontinuum in the 1.95–2.5 μm range covering a transparency window of the atmosphere. The supercontinuum was generated from the Tm-doped all-fiber MOPA lasers. The average output power of the picosecond linear-cavity SESAM mode-locked seed lasers operating at 46 and 77 MHz was as low as 6.7 and 2.6 mW, respectively. The corresponding one-stage silica-based fiber amplifier generated a supercontinuum with 5.06 and 6.83 W average power, 550 and 500 nm bandwidths at −10 dB level, and 5 and 8 dB spectral flatness, respectively.

Bone quality assessment in type 2 diabetes mellitus

The increased risk for fractures in type 2 diabetes mellitus (T2DM) despite higher average bone density is unexplained. This study assessed trabecular bone quality in T2DM using the trabecular bone score (TBS). The salient findings are that TBS is decreased in T2DM and low TBS associates with worse glycemic control. Type 2 diabetes mellitus is a risk factor for osteoporotic fractures despite high average bone mineral density (BMD). The aim of this study was to compare BMD with a noninvasive assessment of trabecular microarchitecture, TBS, in women with T2DM. In a cross-sectional study, trabecular microarchitecture was examined in 57 women with T2DM and 43 women without diabetes, ages 30 to 90years. Lumbar spine BMD was measured by dual-emission x-ray absorptiometry (DXA), and TBS was calculated by examining pixel variations within the DXA images utilizing TBS iNsight software. Mean TBS was lower in T2DM (1.228 ± 0.140 vs. 1.298 ± 0.132, p = 0.013), irrespective of age. Mean BMD was higher in T2DM (1.150 ± 0.172 vs. 1.051 ± 0.125, p = 0.001). Within the T2DM group, TBS was higher (1.254 ± 0.148) in subjects with good glycemic control (A1c ≤ 7.5%) compared to those (1.166 ± 0.094; p = 0.01) with poor glycemic control (A1c > 7.5%). In T2DM, TBS is lower and associated with poor glycemic control. Abnormal trabecular microarchitecture may help explain the paradox of increased fractures at a higher BMD in T2DM. Further studies are needed to better understand the relationship between glycemic control and trabecular bone quality.

Direct Growth of Flower‐Like δ‐MnO2 on Three‐Dimensional Graphene for High‐Performance Rechargeable Li‐O2 Batteries

A challenge still remains to develop high‐performance and cost‐effective air electrode for Li‐O2 batteries with high capacity, enhanced rate capability and long cycle life (100 times or above) despite recent advances in this field. In this work, a new design of binder‐free air electrode composed of three‐dimensional (3D) graphene (G) and flower‐like δ‐MnO2 (3D‐G‐MnO2) has been proposed. In this design, graphene and δ‐MnO2 grow directly on the skeleton of Ni foam that inherits the interconnected 3D scaffold of Ni foam. Li‐O2 batteries with 3D‐G‐MnO2 electrode can yield a high discharge capacity of 3660 mAh g−1 at 0.083 mA cm−2. The battery can sustain 132 cycles at a capacity of 492 mAh g−1 (1000 mAh gcarbon −1) with low overpotentials under a high current density of 0.333 mA cm−2. A high average energy density of 1350 Wh Kg−1 is maintained over 110 cycles at this high current density. The excellent catalytic activity of 3D‐G‐MnO2 makes it an attractive air electrode for high‐performance Li‐O2 batteries.

Can the interior structure influence the habitability of a rocky planet?

Motivation: The most likely places for finding life outside the Solar System are rocky planets, some of which may have surface conditions allowing for liquid water, one of the major prerequisites for life. Greenhouse gases, such as carbon dioxide (CO2), play an important role for the surface temperature and, thus, the habitability of an extrasolar planet. The amount of greenhouse gases in the atmosphere is in part determined by their outgassing from the interior.Method: We use a two-dimensional convection model to calculate partial melting and the amount of CO2 outgassed for Earth-sized stagnant-lid planets. By varying the planetary mass, we investigate the evolution of a secondary atmosphere dependent on the interior structure (different ratio of planetary to core radius). We further study the likelihood for plate tectonics depending on the interior structure and investigate the influence of plate tectonics on outgassing.Results: We find that for stagnant-lid planets the relative size of the iron core has a large impact on the production of partial melt because a variation in the interior structure changes the pressure gradient and thereby the melting temperature of silicate rocks with depth. As a consequence, for planets with a large core (a radius of at least 70–75% of the planet′s radius), outgassing from the interior is strongly reduced in comparison to a planet with the same radius but a small core. This finding suggests that the outer edge of the habitable zone of a star not only depends on the distance from the star and thus the solar influx but also is further limited by small outgassing for stagnant-lid planets with a high average density, indicating a high iron content (e.g. Mercury and the recently detected exoplanets Kepler-10b and CoRoT-7b). This contradicts previous models that have assumed CO2 reservoirs being in principle unlimited for all planets. If plate tectonics is initiated, several tens of bars of CO2 can be outgassed in a short period of time – even for planets with a large iron core – and the outer boundary of the habitable zone is not influenced by the interior structure. It is, however, more difficult for planets with a thin mantle (in our test case, with a thickness of 10% of the planet′s radius) to initiate plate tectonics.Our results indicate that the interior structure may strongly influence the amount of CO2 in planetary atmospheres and, thereby, the habitability of rocky planets. To obtain better constraints on the interior structure accurate measurements of size and mass are necessary.

Light-Weight Masonry Mortarswith Hollow Glass Microspheres for Winter Conditions

In the paper the research results of light-weight masonry mortars with hollow glass microspheres (HGMS) and antifreeze admixtures (AFA) for masonry walling of the efficient small items at the low temperatures are given. One has chosen the antifreeze admixtures for the mortars and their rate has been justified. The main properties of the masonry mortars with HGMS and the antifreeze admixtures have been determined. The standard research methods are used. Main attention was paid to the analysis of strength of the mortar with HGMS and the antifreeze admixtures formed at the positive and negative temperatures. The optimal mixtures for the temperature down to 10 °C were developed. A priority direction of development of construction science currently is energy saving and the improvement of energy efficiency of buildings and structures. A part of the solution to this problem is the development of efficient building materials and fencing structures. The use of multi-layer fencing structures is known to lead to a decrease in the coefficient of their thermal uniformity [. In this regard, the most promising is the development of single-wall exterior fencing structures, which answer the requirements of the standards for thermal protection. However, single-wall fencing structures answering the requirements for thermal protection must have an average density value not greater than 500 kg/m3. The materials from cellular concrete, polystyrene concrete, foam ceramics concrete and others satisfy the aforesaid requirements. The monolith unity of similar structures is provided through the use of mortars on the basis of mineral, mineral-and-polymer and polymer binders [2-. Such mortars with high average density and a high coefficient of thermal conductivity are the bridges of cold in the construction; they do not provide the thermal homogeneity of the fencing structure and reduce its thermal resistance. A solution to this problem is the use of light-weight masonry mortars (warm mortars). Such mortars with traditional light-weight fillers (e.g. expanded perlite and vermiculite mortar sands) have an increased water requirement, and, as a consequence, the extremely low strength value. Recently, hollow glass (HGMS) or ceramics (CMS) microspheres are used as light-weight fillers for masonry mortars [. Thus, in [ the scientific principles of the use of such compositions with HGMS have been developed. The masonry mortar has been obtained with the following properties: average density of dried mortar is 450 kg/m3 with a coefficient of thermal conductivity equal to 0.17 W/m·°C and a compressive strength equal to 3.2 MPa at the age of 28 days, water-retention capacity over 90% and with optimal technological and rheological characteristics [.

Field-Effect Modulation of Thermoelectric Properties in Multigated Silicon Nanowires

Electric-field-induced charge carriers typically exhibit greater mobility over carriers contributed by chemical dopants and offer a powerful mechanism for thermoelectric power factor enhancement. We fabricate multigated silicon nanowires (Si NWs) and demonstrate significant modulation of electrical conductivity and the Seebeck coefficient with gate bias. Because of the higher mobility of field-effect charge carriers, we demonstrate that power factor for the gated Si NWs is similar to the highest values reported for n-type Si nanostructures despite charge transport only occurring at the NW surface. Field-effect doping is a promising strategy for optimizing power factor and may result in significant power factor enhancement in smaller diameter Si NWs where high average carrier densities can be obtained with induced surface charge.

The mesozooplankton community of the Belgian shelf (North Sea)

This manuscript presents the mesozooplankton community structure and its spatial and temporal variabilities in the Belgian part of the North Sea (BPNS), a first thorough study on this topic in nearly 40years. Monthly sampling campaigns at ten stations in the BPNS in 2009 and 2010 yielded a total of 137 mesozooplankton taxa (46 holoplanktonic, 50 meroplanktonic and 41 tychoplanktonic), of which nine species had never been reported in the area. Smaller neritic copepods, especially Temora longicornis and Acartia clausi, were present in all samples and dominated zooplankton densities (66%), together with the appendicularian Oikopleura dioica (10%). They were joined by high numbers of meroplanktonic echinoderm larvae (9%) in spring and summer. Based on diversity alone, the mesozooplankton could be typified as one neritic zooplankton community, due to the ubiquitous presence in time and space of the dominant copepods. Yet, these neritic species were often joined by low numbers of oceanic species that are occasionally imported with the inflow of Atlantic oceanic water in the BPNS. Based on a combination of abundance and diversity, our results indicate distinct seasonal and spatial distribution patterns in the mesozooplankton. Months with highest average densities were May, June and July, lowest densities were noted in December and January. Only limited long-term zooplankton data are available for the BPNS from the Continuous Plankton Recorder surveys or the long-term monitoring stations in the vicinity of our research area. However, our data suggest that nowadays zooplankton species appear earlier in the BPNS, comparable with other areas in the North Sea. Densities varied between 150 and 15,000ind.m−3, and averaged highest at midshore stations, then nearshore and offshore. This is partially comparable with the spatial patterns recorded for other ecosystem components, such as demersal fish, epibenthos and macrobenthos, of which densities peak in a stretch almost parallel to but some miles away from the coastline in the BPNS.

A kinematic wave approach to traffic statics and dynamics in a double-ring network

Recently there has been much interest in understanding macroscopic fundamental diagrams of stationary road networks. However, there lacks a systematic method to define and solve stationary states in a road network with complex junctions. In this study we propose a kinematic wave approach to defining, analyzing, and simulating static and dynamic traffic characteristics in a network of two ring roads connected by a 2×2 junction, which can be either an uninterrupted interchange or a signalized intersection. This study is enabled by recently developed macroscopic junction models of general junctions. With a junction model based on fair merging and first-in-first-out diverging rules, we first define and solve stationary states and then derive the macroscopic fundamental diagram (MFD) of a stationary uninterrupted network. We conclude that the flow-density relationship of the uninterrupted double-ring network is not unique for high average network densities (i.e., when one ring becomes congested) and unveil the existence of infinitely many stationary states that can arise with a zero-speed shockwave. From simulation results with a corresponding Cell Transmission Model, we verify that all stationary states in the MFD are stable and can be reached, but show that randomness in the retaining ratio of each ring drives the network to more symmetric traffic patterns and higher flow-rates. Furthermore we model a signalized intersection as two alternate diverge junctions and demonstrate that the signalized double-ring network can reach asymptotically periodic traffic patterns, which are therefore defined as “stationary” states in signalized networks. With simulations we show that the flow-density relation is well defined in such “stationary” states, and asymptotic traffic patterns can be impacted by signal cycle lengths and retaining ratios. But compared with uninterrupted interchanges, signalized intersections lead to more asymmetric traffic patterns, lower flow-rates, and even gridlocks when the average density is higher than half of the jam density. The results are consistent between this study and existing studies, but the network kinematic wave model, with appropriate junction models, is mathematically tractable and physically meaningful. It has offered a more complete picture regarding the number and type of stationary states, their stability, and MFD in freeway and signalized networks.

How lonely they are? A degree of isolation among macrozoobenthos species in the Marine Protected Area, the Bay of Puck, the Southern Baltic

Abstract Extensive sampling (450 grabs) was performed all over the inner part of Puck Bay (105 km2 area) in summers of 2007–2009. The GIS-based analysis of samples was performed to assess in detail the distribution of 32 benthic species. The minimum area of occurrence was less than 1 km2 for Lekanosphaera rugicauda and the maximum was 83 km2 for Cerastoderma glaucum. The material reveals that species with the pelagic larval stage were most widespread, with the least distance between individuals and the highest average density (e.g. Cerastoderma glaucum, Hydrobia ventrosa). The most isolated and the least dense species within the studied area were discretely mobile, non-larval crustaceans (e.g. Gammarus oceanicus and Lekanosphaera rugicauda), present at single sites with the largest distance from each other. We conclude that analysis of species distribution helps in understanding the threats to populations of marine invertebrates and marine spatial planning, through locating the isolated species and populations.

The interior structure of Mercury constrained by the low-degree gravity field and the rotation of Mercury

Among all the planets of the solar system Mercury stands out, because it has a relatively high average density compared to its size. To account for this high density, Mercuryʼs core radius is thought to be larger than 34 of its radius. Here, we use recent data about the second-degree gravity field coefficients and measurements about Mercuryʼs rotation – obliquity and 88-day libration amplitude – to obtain constraints on Mercuryʼs interior structure. By combining the gravity field data and the obliquity measurements, the mean moment of inertia of Mercury can be determined. If the coupling between the core and the mantle is neglected then the gravity field data together with the libration amplitude provide an estimate of Mercuryʼs silicate shell moment of inertia. However, since the effect of core–mantle coupling on the 88-day libration amplitude can be about as large as the libration amplitudeʼs uncertainty (Van Hoolst et al., 2012) we use as data the mean moment of inertia and the 88-day libration amplitude to infer knowledge about Mercuryʼs interior structure.We use two different interior modeling approaches. The first one is based on Rivoldini et al. (2009) and uses a set of 5 mantle mineralogies, a crust with a given thickness and density, and two mantle temperatures. In the second setting the density of the mantle, the thickness, and density of the crust, and the temperature of the core mantle boundary are parameters of the model. In both cases, we assume that the core is made of iron and the light element sulfur and use the temperature, pressure, and the concentration of sulfur in the core together with the melting temperature of iron–sulfur to determine the radius of the inner core.Our results show that the data provide a strong constraint on the radius of the core and on its average density or equivalently on the fraction of sulfur in the core if sulfur is the only light element in the core. We find that Mercury has a core radius of 2004±39 km, an average core density of 7233±267 kg/m3, and a sulfur fraction of 4.5±1.8 wt%. The other parameters of the model, in particular the density of the mantle are however, only weakly constrained by the data. The geodesy data can also not distinguish between a fully liquid core and the existence of an inner core.