The Spherically Symmetric Gravitational Collapse of a Clump of Solids in a Gas

Several mechanisms have been identified that create dense particle clumps in the solar nebula. The present work is concerned with the gravitational collapse of such clumps, idealized as being spherically symmetric. Calculations using the two-fluid model are performed (almost) up to the time when a central density singularity forms. The end result of the study is a parametrization for this time, in order that it may be compared with timescales for various disruptive effects to which clumps may be subject. An important effect is that as the clump compresses, it also compresses the gas due to drag. This increases gas pressure which retards particle collapse and leads to oscillation in the size and density of the clump. The ratio of gravitational force to gas pressure gives a two-phase Jeans parameter, $J_t$, which is the classical Jeans parameter with the sound speed replaced by an the wave speed in a coupled two-fluid medium. Its use makes the results insensitive to the initial density ratio of particles to gas as a separate parameter. An ordinary differential equation model is developed which takes the form of two coupled non-linear oscillators and reproduces key features of the simulations. Finally, a parametric study of the time to collapse is performed and a formula (fit to the simulations) is developed. In the incompressible limit $J_t \to 0$, collapse time equals sedimentation time. As $J_t$ increases, the collapse time decreases roughly linearly with $J_t$ until $J_t \gtrsim 0.4$ when it becomes approximately equal to the dynamical time

British Bangladeshi Muslim Women’s In-Law Relationships: A Narrative Analysis

Despite being a major feature of everyday life, research on in-law relationships has received relatively scant attention in comparison to other close relationships. In-law relationships have mostly been portrayed negatively in popular culture, influencing and reflecting the pervading negative attitudes held by wider society. This has provided a narrow and restrictive view of affinal relationships. In-law relationships are found across the globe, and literature suggests that culture and its underlying values play a major role in shaping the nature and dynamics of such relationships. However, the majority of research has been dominated by the mother-in-law/daughter-in-law dyad, with little attention to the wider context. Using a post-colonial feminist framework and narrative analysis, the current research documents the stories of 10 British Bangladeshi Muslim women and their subjective experiences of in-law relationships. The research highlights the subtle and nuanced way they navigate in-law relationships and exercise their agency. It also demonstrates how intersecting markers of difference impact experiences of agency and the shaping of their identity. The research highlights four major themes from the analysis: (1) “It’s a family marriage” (2) Rising tensions (3) Tug of war – the role of husband and (4) Developing a survivor’s identity. A description of these themes and related subthemes are discussed. The findings of the present study challenge Eurocentric models of feminism and demonstrate the diversity of women’s experiences and identities. They also reveal how gender intersects with other markers of identity that shape the participants’ social realities. They also point to the urgency of highlighting the role of the wider family in the perpetration of abuse against women. The research discusses further implications of findings for academics, clinicians, policy, and the wider community, and recommends suggestions for future research

Dualisme Kebijakan Pelayaran Dan Perikanan (Studi Tentang Implementasi Kepmen Perhubungan No KM 46 Tahun 1996 Tentang Sertifikasi Kelaiklautan Kapal Penangkap Ikan Dan Permen Kelautan Dan Perikanan No 07 Tahun 2010 Tentang Surat Laik Operasi Kapal Perikan

: Dualism of Shipping and Fisheries Policy (Study on Implementation of the Decree of Transport Ministers No. KM 46 of 1996 on the Worthiness Certification of Fishing Vessels and Minister of Marine and Fisheries Regulations No. 07 of 2010 on Fishing Vessels Operating Worthy Letters in Coast Fishery Port Mayangan, Probolinggo City). Worthiness of fishing vessels is a matter that needs to be considered because it involves the safety and security of shipping, include safety and security of the ship, fisherman, and maritime environments. Ship was granted permission to sail the ship that has qualified administrative and technical feasibility of the ship issued by the harbormaster after fulfilling worthy Letter of Operations. In facts, There are two institutions that have the same duties and authority of the operational inspection fishing boats in Coast Fishery Port Mayangan Probolinggo, the Department of Transportation and Department Maritime Affairs and Fisheries. Both of the institute has the right because they have legitimate legal basis as governed in Act No. 17 of 2008 on the shipping by Department of Transportation, and Act No. 45 of 2009 on Fisheries by the Department of Marine and Fisheries. The existence of the same authority both of institutions have an impact on actors in the fisheries, include many of permit makes the costs incurred by business actors increased, and many of permits also affect to performance of the fishermen fishing

Morphological Variations of Explosive Residue Particles and Implications for Understanding Detonation Mechanisms

The possibility of recovering undetonated explosive residues following detonation events is well known, however, the morphology and chemical identity of these condensed phase post-blast particles remains undetermined. An understanding of the post-blast explosive particle morphology would provide vital information during forensic examinations, allowing rapid initial indication of the explosive material to be microscopically determined prior to any chemical analyses, and thereby saving time and resources at the crucial stage of an investigation. In this study, condensed phase particles collected from around the detonations of aluminized ammonium nitrate and RDX-based explosive charges were collected in a novel manner utilising SEM stubs. By incorporating the use of a focused ion beam during analysis, for the first time it has been possible to determined that such particles have characteristic shapes, sizes and internal structures depending on the explosive and the distance from the detonation at which particles are recovered. Spheroidal particles (10 µm to 210 µm) with micro surface features recovered following inorganic charge detonations were dissimilar to the irregularly shaped particles (5 µm to 100 µm) recovered following organic charge firings. Confirmatory analysis to conclude the particles were indeed explosive included HPLC-MS, Raman spectroscopy and MeV-SIMS. The results impact not only on forensic investigation but also on the theoretical constructs which govern detonation theory by indicating the potential mechanisms by which these particles survive and how this varies between the different explosive types

Cosmological Solution in M-theory on S^1/Z_2

We provide the first example of a cosmological solution of the Horava-Witten supergravity. This solution is obtained by exchanging the role of time with the radial coordinate of the transverse space to the five-brane soliton. On the boundary this corresponds to rotating an instanton solution into a tunneling process in a space with Lorentzian signature, leading to an expanding universe. Due to the freedom to choose different non-trivial Yang-Mills backgrounds on the boundaries, the two walls of the universe ( visible and hidden worlds) expand differently. However at late times the anisotropy is washed away by gravitational interactions.Comment: 10 pages, latex, no figur

The characterisation and provenance of ammunition components

© Cranfield University, 2018The objective was to create a comprehensive data set of analytical results relating to the physical construction and chemical composition of ammunition components; to be used to determine the provenance of ammunition. The study focusses on 7.62 x 39 mm ammunition due to its ubiquitous nature in crime and conflict zones around the world. Ammunition identification and classification currently relies heavily on the information provided on cartridge case headstamps and packaging. In the absence of this information, there is no definitive method to ascertain the potential origin of ammunition. The aim of this study was to examine the physical and chemical composition of ammunition components from different origins in an attempt to establish if the construction and elemental composition of these components could be used to differentiate between sources of ammunition. Initially, various physical and chemical techniques were employed to analyse samples of ammunition from known sources. Currently, there are 24 known countries and 42 known manufacturers who produced 7.62 x 39 mm ammunition (Ness and William, 2011). This study aimed to analyse a representative sample of 7.62 x 39 mm ammunition to determine if differentiation between the manufacturers is feasible. A further temporal study was explored to establish if differences in the materials and manufacturing techniques occurred in a single manufacturing plant over a period of time. A detailed analysis of ammunition components generated information pertaining to differences particular to each manufacturer’s ammunition. It is reported that there are sufficient distinguishing features between the 7.62 x 39 mm ammunition analysed, and can be said with a degree of certainty that a particular round of 7.62 x 39 mm ammunition could have originated from a particular manufacturer. This research was conducted with the ambition of creating a publication to be used by professionals and academics in relation to identification of ammunition origin. Working with Cranfield University to contribute to work conducted by national and international organisations it is presented as a database set; to be used as a reference where standard forensic techniques currently provide no information of the provenance ammunition origin. Promising results provide avenues for further research to be continued temporally or even into other calibres – ultimately comprising of a resource that is invaluable to many

Demonstration of fine pitch FCOB (Flip Chip on Board) assembly based on solder bumps at Fermilab

Bump bonding is a superior assembly alternative compared to conventional wire bond techniques. It offers a highly reliable connection with greatly reduced parasitic properties. The Flip Chip on Board (FCOB) procedure is an especially attractive packaging method for applications requiring a large number of connections at moderate pitch. This paper reports on the successful demonstration of FCOB assembly based on solder bumps down to 250um pitch using a SUESS MA8 flip chip bonder at Fermilab. The assembly procedure will be described, microscopic cross sections of the connections are shown, and first measurements on the contact resistance are presented.Comment: 4 pages, 8 figure

Relationship between the molecular composition, visible light absorption, and health-related properties of smoldering woodsmoke aerosols

Organic aerosols generated from the smoldering combustion of wood critically impact air quality and health for billions of people worldwide; yet, the links between the chemical components and the optical or biological effects of woodsmoke aerosol (WSA) are still poorly understood. In this work, an untargeted analysis of the molecular composition of smoldering WSA, generated in a controlled environment from nine types of heartwood fuels (African mahogany, birch, cherry, maple, pine, poplar, red oak, redwood, and walnut), identified several hundred compounds using gas chromatography mass spectrometry (GCMS) and nano-electrospray high-resolution mass spectrometry (HRMS) with tandem multistage mass spectrometry (MSn). The effects of WSA on cell toxicity as well as gene expression dependent on the aryl hydrocarbon receptor (AhR) and estrogen receptor (ER) were characterized with cellular assays, and the visible mass absorption coefficients (MACvis) of WSA were measured with ultraviolet-visible spectroscopy. The WSAs studied in this work have significant levels of biological and toxicological activity, with exposure levels in both an outdoor and indoor environment similar to or greater than those of other toxicants. A correlation between the HRMS molecular composition and aerosol properties found that phenolic compounds from the oxidative decomposition of lignin are the main drivers of aerosol effects, while the cellulose decomposition products play a secondary role; e.g., levoglucosan is anticorrelated with multiple effects. Polycyclic aromatic hydrocarbons (PAHs) are not expected to form at the combustion temperature in this work, nor were they observed above the detection limit; thus, biological and optical properties of the smoldering WSA are not attributed to PAHs. Syringyl compounds tend to correlate with cell toxicity, while the more conjugated molecules (including several compounds assigned to dimers) have higher AhR activity and MACvis. The negative correlation between cell toxicity and AhR activity suggests that the toxicity of smoldering WSA to cells is not mediated by the AhR. Both mass-normalized biological outcomes have a statistically significant dependence on the degree of combustion of the wood. In addition, our observations support the fact that the visible light absorption of WSA is at least partially due to charge transfer effects in aerosols, as previously suggested. Finally, MACvis has no correlation with toxicity or receptor signaling, suggesting that key chromophores in this work are not biologically active on the endpoints tested