Contamination of spacecraft by recontact of dumped liquids

Liquids partially freeze when dumped from spacecraft producing particles which are released into free space at various velocities. Recontact of these particles with the spacecraft is possible for specific particle sizes and velocities and, therefore, can become contamination for experiments within the spacecraft or released experiments as a result of waste and potable water dumped from Space Shuttle. An examination of dump characteristics was conducted on STS-29 using both on-board video records and ground based measurements. A preliminary analysis of data from this flight indicates particle velocities are in the range of 30 to 75 ft/sec and recontact is possible for limited particle sizes

Alsophis rufiventris

Number of Pages: 4Integrative BiologyGeological Science

Modified Appleby Procedure with Arterial Reconstruction for Locally Advanced Pancreatic Adenocarcinoma: A Literature Review and Report of Three Unusual Cases.

BACKGROUND: Pancreatic body and tail ductal adenocarcinomas are often diagnosed with local vascular invasion of the celiac axis (CA) and its various branches. With such involvement, these tumors have traditionally been considered unresectable. The modified Appleby procedure allows for margin negative resection of some such locally advanced tumors. This procedure involves distal pancreatectomy with en bloc splenectomy and CA resection and relies on the presence of collateral arterial circulation via an intact pancreaticoduodenal arcade and the gastroduodenal artery to maintain prograde hepatic arterial perfusion. When the resultant collateral circulation is inadequate to provide sufficient hepatic and gastric arterial inflow, arterial reconstruction (AR) is necessary to supercharge the inflow. Herein, we review all reported cases of AR with modified Appleby procedures that we have identified in the literature, and we report our experience of three recent cases with arterial reconstruction including two cases with arterial bypasses not requiring interposition grafting. METHODS: Perioperative and oncologic outcomes from our Institutional Review Board-approved database of pancreatic resections at the Thomas Jefferson University were reviewed. Additionally, PubMed search for cases of distal or total pancreatectomy with celiac axis resection and concurrent AR was performed. RESULTS: From the literature, 12 reports involving 28 patients were identified of distal and total pancreatectomy with AR after CA resection. The most common AR in the literature, performed in 12 patients, was a bypass from the aorta to the common hepatic artery (CHA) using a variety of interposition conduits. In our institutional experience, patient #1 had a primary side-to-end aorto-CHA bypass, patient #2 had a primary end-to-end bypass of the transected distal CHA to the left gastric artery in the setting a replaced left hepatic artery, and patient #3 required an aortic to proper hepatic artery bypass with saphenous vein graft and portal venous reconstruction. All patients recovered from their operations without ischemic complications, and they are currently 16, 15, and 13 months post-op, respectively. CONCLUSIONS: The criteria for resectability in patients with locally advanced pancreatic body and tail neoplasms are expanding due to increasing experience with AR in the setting of the modified Appleby procedure. When performing AR, primary arterial re-anastomosis may be considered preferable to interposition grafting as it decreases the potential for the infectious and thrombotic complications associated with conduits and it reduces the number of vascular anastomoses from two to one. Consideration must also be given to normal variant anatomy of the hepatic circulation during operative planning as the origin of the left gastric artery is resected with the CA. The modified Appleby procedure with AR, when used in appropriately selected patients, offers the potential for safe, margin negative resection of locally advanced pancreatic body and tail tumors

Inferring Species Trees Directly from Biallelic Genetic Markers: Bypassing Gene Trees in a Full Coalescent Analysis

The multi-species coalescent provides an elegant theoretical framework for estimating species trees and species demographics from genetic markers. Practical applications of the multi-species coalescent model are, however, limited by the need to integrate or sample over all gene trees possible for each genetic marker. Here we describe a polynomial-time algorithm that computes the likelihood of a species tree directly from the markers under a finite-sites model of mutation, effectively integrating over all possible gene trees. The method applies to independent (unlinked) biallelic markers such as well-spaced single nucleotide polymorphisms (SNPs), and we have implemented it in SNAPP, a Markov chain Monte-Carlo sampler for inferring species trees, divergence dates, and population sizes. We report results from simulation experiments and from an analysis of 1997 amplified fragment length polymorphism (AFLP) loci in 69 individuals sampled from six species of {\em Ourisia} (New Zealand native foxglove)

An analysis of globalisation in international business research 1993–2018: rise of the sceptics

Purpose: The aim of this article is to provide an analysis of the current state of international business research on the topic of globalisation and to guide researchers who are new to international business research as to which journals and authors to consult when studying this phenomenon. Design: The article presents a bibliometric analysis using the Web of Science database. A multiple correspondence analysis provides a map of keywords and authors, as well as a framework for tracking globalisation literature over the 26 years, 1993–2018. Findings: The findings identify several fundamental themes and significant gaps in the extant literature; the most alarming gap centres around the effect of globalisation on social issues and, consequently, the rise of the anti-globalisation crusaders. Practical Implications: A distinctive contribution of this study is that it investigates the intersection between globalisation and international business. We seek to expose the intellectual structure of globalisation research, identify existing and emerging themes of globalisation research, and discuss future research streams. Social Implications: Our findings show the rise of the globalisation sceptic and reveal the mounting concerns regarding the unequal benefits of globalisation. Originality/Value: There are two key benefits of this review. First, we identify a swing from an alignment of globalisation with the transformationalist viewpoint to rising support in favour of the sceptical viewpoint – a fact that is fuelling the anti-globalisation crusaders. Second, the review has the potential to guide scholars on precisely what needs to be explored in IB globalisation research

Characterizing Single Polymeric and Protein Nanoparticles with Surface Plasmon Resonance Imaging Measurements

Near-infrared surface plasmon resonance imaging (SPRI) microscopy is used to detect and characterize the adsorption of single polymeric and protein nanoparticles (PPNPs) onto chemically modified gold thin films in real time. The single-nanoparticle SPRI responses, Δ%R_(NP), from several hundred adsorbed nanoparticles are collected in a single SPRI adsorption measurement. Analysis of Δ%R_(NP) frequency distribution histograms is used to provide information on the size, material content, and interparticle interactions of the PPNPs. Examples include the measurement of log-normal Δ%R_(NP) distributions for mixtures of polystyrene nanoparticles, the quantitation of bioaffinity uptake into and aggregation of porous NIPAm-based (N-isopropylacrylamide) hydrogel nanoparticles specifically engineered to bind peptides and proteins, and the characterization of the negative single-nanoparticle SPRI response and log-normal Δ%R_(NP) distributions obtained for three different types of genetically encoded gas-filled protein nanostructures derived from bacteria

Catastrophe theory, symmetry breaking and the pseudo Jahn-Teller effect

This research focuses on the structural symmetry breaking observed in hypovalent silicon containing compounds. The structural symmetry breaking was studied from the perspective of the pseudo Jahn-Teller effect (pJTE). A density functional theory (DFT) based approach to assessing the pJTE parameters was developed to provide a computationally cost-effective alternative to the post Hartree-Fock procedures typically employed. Additionally, elementary catastrophe theory models were applied to gain a deeper insight into cases where the description of electronic structure by multiple quantum chemical methods are incongruous with one another. The symmetry breaking of hypovalent silicon containing compounds was studied by examining Si-analogs of a series of a planar cyanocarbons: tetracyanoethylene (TCNE), tetracyanoquinodimethane (TCNQ), tetracyanodiphenoquinodimethane (TCNDQ) and tetracyanopyrenoquinodimethane (TCNP). Si-substitution generally resulted in structural symmetry breaking of both the neutral and anionic forms which enhanced their electron affinities. Moreover, Si-substitution was found to enhance the singlet and triplet diradical character of the π-conjugated systems. The choice of density functional was found to have an impact on whether or not the pJTE was observed. This was studied in further detail by evaluating the effect of exact exchange on the description of the adiabatic potential energy surfaces (APESs) of disilene and 2Si TCNQ using the cusp catastrophe model. Functionals containing high amounts of exact exchange were found not to display the symmetry breaking effect. The elliptic umbilic catastrophe was also applied to the study of the electronic structure of isothiirane. Furthermore, commonly used post analysis tools, the Quantum Theory of Atoms in Molecules and Natural Resonance Theory, were critically assessed. The results of this study resolved an open question in the literature regarding the description of the electronic structure of isothiirane. The pJTE parameters were evaluated using DFT by employing a model Hamiltonian that accounts for vibronic interactions. This model Hamiltonian was fit to cross-sections of the APES along the distorting mode. Best practices regarding the evaluation of pJTE parameters were also described. The procedure outlined in this thesis is applicable to the study of any pJTE problem where post Hartree-Fock methods are not feasible