Generalized model of blockage in particulate flow limited by channel carrying capacity

We investigate stochastic models of particles entering a channel with a random time distribution. When the number of particles present in the channel exceeds a critical value $N$, a blockage occurs and the particle flux is definitively interrupted. By introducing an integral representation of the $n$ particle survival probabilities, we obtain exact expressions for the survival probability, the distribution of the number of particles that pass before failure, the instantaneous flux of exiting particle and their time correlation. We generalize previous results for $N=2$ to an arbitrary distribution of entry times and obtain new, exact solutions for $N=3$ for a Poisson distribution and partial results for $N\ge 4$.Comment: 13 pages, 9 figure

Why is modern capitalism irresponsible and what would make it more responsible? A company law perspective

In this paper, we claim that capitalism is inherently irresponsible precisely because production and distribution to meet the needs of society are subordinated to profit maximisation. Historically, the corporate form enhanced that irresponsibility by accommodating rentier shareholders—whose only concern is with the income generated by their shares— by limiting their liability and by treating the company in law as separate from shareholders and their property, the fungible and fully transferable share. We show how this irresponsibility was somewhat countered in the post war period by government policy and an empowered and active labour movement, but re-emerged in the late 1970s when the economy could no longer support both rentier and labour interests. Since then, company law has enabled various financialised methods of increasing shareholder returns at the cost of innovation, productivity and returns to labour. We recommend policies to reform the company by reducing rentier-driven irresponsibility. Finally, we argue that existing responsible company forms such as the community interest company cannot create a more responsible capital while the limited liability company continues to provide substantial benefits to the alliance between rentiers and executives

Aerosol major ion record at Mount Washington

This study examined the seasonal cycles and regional-scale meteorological controls on the chemical properties of bulk aerosols collected from 1999 to 2004 at Mount Washington, the highest peak in the northeastern United States. The concentrations of NH4+ and SO42− peaked during summer months. The pattern for aerosol NO3− was more complicated with relatively high median concentrations characterizing spring and summer months, but with major elevated events occurring during fall, winter, and spring. The seasonal relationship between NH4+ and SO42− indicated that during warmer months a mixture of (NH4)2SO4 and NH4HSO4 was present, while it was mainly the latter in winter. More acidity and higher concentrations of the major species were generally associated with winds from the southwest and west sectors. The highest (≥95th percentile) concentrations of SO42− and NH4+ were associated with air mass transport from major upwind source regions in the Midwest and along the eastern seaboard. The ionic composition and seasonal cycle observed at Mount Washington were similar to those measured at other northeastern sites, but the range and average concentrations were much lower. These differences were exaggerated during wintertime. Included in this paper are several Eulerian case studies of SO2 conversion to SO42− during transit from Whiteface Mountain, New York, to Mount Washington. The calculations suggest a gas-phase SO2 oxidation rate of ∼1–2% per hour and demonstrate the possibility of using these two sites to investigate the chemical evolution of air masses as they move from Midwestern source regions to northern New England

Internal Flows and Particle Transport Inside Picoliter Droplets of Binary Solvent Mixtures

The flows in evaporating droplets of binary mixtures are much more complicated than single solvent systems. Solutal Marangoni flows are generated due to differential evaporation of components. High-speed imaging techniques are used to visualize how internal flows transport particles to build up the end deposit. Circulatory flow along streamlines develops inside droplets at the contact line or central region, depending on the direction of the Marangoni flow. Re-circulation of particles can reduce the build up of a ring stain. Additionally, particles migrate across streamlines to collect at the droplet center independent of where the circulating regions occur. Potential mechanisms for particle migration are discussed, including chemophoresis, thermophoresis and shear-induced migration

Species-specific responses to landscape features shaped genomic structure within Alaska galliformes

Aim: Connectivity is vital to the resiliency of populations to environmental change and stochastic events, especially for cold-adapted species as Arctic and alpine tundra habitats retract as the climate warms. We examined the influence of past and current landscapes on genomic connectivity in cold-adapted galliformes as a critical first step to assess the vulnerability of Alaska ptarmigan and grouse to environmental change. We hypothesize that the mosaic of physical features and habitat within Alaska promoted the formation of genetic structure across species. Location: Alaska, United States of America. Taxa: Ptarmigan and Grouse (Galliformes: Tetraoninae). Methods: We collected double digest restriction-site- associated DNA sequence data from six ptarmigan and grouse species (N = 13–145/ species) sampled across multiple ecosystems up to ~10 degrees of latitude. Spatial genomic structure was analysed using methods that reflect different temporal scales: (1) principal components analysis to identify major trends in the distribution of genomic variation; (2) maximum likelihood clustering analyses to test for the presence of multiple genomic groupings; (3) shared co-ancestry analyses to assess contemporary relationships and (4) effective migration surfaces to identify regions that deviate from a null model of isolation by distance. Results: Levels of genomic structure varied across species (ΦST =0.009–0.042). Three general patterns of structure emerged: (1) east-west partition located near the Yukon-Tanana uplands; (2) north-south split coinciding with the Alaska Range and (3) northern group near the Brooks Range. Species-specific patterns were observed; not all landscape features were barriers to gene flow for all ptarmigan and grouse and temporal contrasts were detected at the Brooks Range. Main conclusions: Within Alaska galliformes, patterns of genomic structure coincide with physiographic features and highlight the importance of physical and ecological barriers in shaping how genomic diversity is arrayed across the landscape. Lack of concordance in spatial patterns indicates that species behaviour and habitat affinities play key roles in driving the contrasting patterns of genomic structure

Operationally Responsive Space (ORS): An Architecture and Enterprise Model for Adaptive Integration, Test and Logistics

The capability to rapidly deploy tactical satellites to meet a Joint Force Commander\u27s immediate battlespace requirements is a well-documented joint capability need. Key U.S. strategic documentation cites the need for the capability to maintain persistent surveillance or an unblinking eye over battlespace and to rapidly reconstitute critical space capabilities to preserve situational awareness. The warfighter requires a tactical space-based deployment capability which employs a request to launch and operational deployment window of 90 to 120 days. This master\u27s thesis executed two (2) major areas of work: apply, and reinforce the Operationally Responsive Space (ORS) mission tasks using the Joint Capabilities Integration Development System (JCIDS) process; then based on capability gap data generated from the process, analyze and define the capability gap of an ORS Adaptive Integration, Test and Logistics (IT&L) process for payload to bus deployment to meet the identified time scales. This document recommends engineering solutions and processes for the ORS IT&L to-be state for this warfighter capability. The ORS adaptive IT&L CONOPS developed as part of this work focuses on the Tactical Satellite Rapid Deployment System (TSRDS), which is an adaptive integration, test and logistics capability that enables rapid and effective payload to bus integration to meet a 90- to 120-day warfighter window

Swain Committee Report

Letter addressed to the Secretary of the Navy, the Honorable Josephus H. Daniels, from the Committee appointed by the President of the Society for the Promotion of Engineering Education, to visit the U.S. Naval Academy in Annapolis, MD. The purpose was to evaluate the work of the Post Graduate School. The committee recommended enlarging the enrollment of the Post Graduate School and providing for appropriate funding for buildings, equipment and curricula

Phylogenomics reveals ancient and contemporary gene flow contributing to the evolutionary history of sea ducks (Tribe Mergini)

Insight into complex evolutionary histories continues to build through broad comparative phylogenomic and population genomic studies. In particular, there is a need to understand the extent and scale that gene flow contributes to standing genomic diversity and the role introgression has played in evolutionary processes such as hybrid speciation. Here, we investigate the evolutionary history of the Mergini tribe (sea ducks) by coupling multi-species comparisons with phylogenomic analyses of thousands of nuclear ddRAD-seq loci, including Z-sex chromosome and autosomal linked loci, and the mitogenome assayed across all extant sea duck species in North America. All sea duck species are strongly structured across all sampled marker types (pair-wise species ΦST \u3e 0.2), with clear genetic assignments of individuals to their respective species, and phylogenetic relationships recapitulate known relationships. Despite strong species integrity, we identify at least 18 putative hybrids; with all but one being late generational backcrosses. Most interesting, we provide the first evidence that an ancestral gene flow event between long-tailed ducks (Clangula hyemalis) and true Eiders (Somateria spp.) not only moved genetic material into the former species, but likely generated a novel species — the Steller’s eider (Polysticta stelleri) — via hybrid speciation. Despite generally low contemporary levels of gene flow, we conclude that hybridization has and continues to be an important process that shifts novel genetic variation between species within the tribe Mergini. Finally, we outline methods that permit researchers to contrast genomic patterns of contemporary versus ancestral gene flow when attempting to reconstruct potentially complex evolutionary histories

Investigations into free tropospheric new particle formation in the central Canadian arctic during the winter/spring transition as part of TOPSE

In this paper, we investigate the role of in situ new particle production in the central Canadian sub-Arctic and Arctic as part of the TOPSE experiment. Airborne measurements conducted primarily in the free troposphere were made from 50° to 90°W longitude and 60° to 85°N latitude during the period from February to May 2000. Data pertinent to this paper include 3–4 nm diameter (Dp) particles, ultrafine condensation nuclei (Dp \u3e 3 nm), fine particles (0.2 \u3c Dp \u3c 3 μm), and the possible nucleation precursor, sulfuric acid, and its precursor, sulfur dioxide. For data averaged over this period, most species showed little evidence for a latitudinal trend. Fine aerosol number concentrations, however, showed a slight increase with latitude. The evolution of various species concentrations over the period of the study show that fine particles also had a consistent temporal trend, increasing at all altitudes from February to May, whereas sulfur dioxide at the surface tended to peak in late March. Ultrafine condensation nuclei and 3–4 nm particles showed no temporal trends. Little evidence for in situ new particle production was observed during the study, except for one atypical event where SO2concentrations were 3.5 ppbv, 2 orders of magnitude higher than typical levels. This paper cannot address the question of whether the observed condensation nuclei were produced in situ by a low particle production rate or transported from lower latitudes