cssi/SciSciGPT-SciSciNet huggingface dataset:
Migrants, refugees and the Egyptian security state

This paper asks why developing countries engage, or not, with their migrant populations, focusing specifically on the Middle East and North Africa (MENA) region. Due to increasingly stringent border controls imposed by traditional migrant-receiving states in Europe and North America and decreasing refugee resettlement rates, hundreds of thousands of migrants and refugees fleeing conflict and poverty in neighbouring African and Arab states have settled in MENA countries. To understand why and how new countries of settlement engage with migrants, this paper uses the case study of Egypt and 59 interviews conducted between September and December 2014 in Cairo and Alexandria. This paper concludes that only some factors from the literature on migration and citizenship are useful in explaining the Egyptian state's engagement with its migrant populations; namely, political economy factors, cultural embeddedness, and host state security interests, though security factors take precedence. To better characterise the type of engagement that Egypt pursues vis-a-vis migrants and refugees, this paper proposes the term 'strategic ambivalence', referring to a policy that aims to neither drive out nor to entirely include migrants and refugees into a host society, but instead aims to maintain the status-quo.
Education Quality and Teaching Practices

Improving school quality with limited resources is a key issue of policy. It has been suggested that instructing teachers to follow specific practices together with tight monitoring of their activities may help improve outcomes in under-performing schools that usually serve poor populations. This paper uses a RCT to estimate the effectiveness of guided instruction methods as implemented in under-performing schools in Chile. The intervention improved performance substantially and by equal amounts for boys and girls. However, the effect is mainly accounted for by children from relatively higher income backgrounds and not for the most deprived. Based on the CLASS instrument we document that quality of teacher-student interactions is positively correlated with the performance of low income students; however, the intervention did not affect these interactions. Guided instruction can improve outcomes, but it is a challenge to reach the most deprived children.
THE ROLE OF ARTHROSCOPY IN THA: LESSONS LEARNED

The purpose of this study is to evaluate the indications and technique of hip arthroscopy for problems associated with total joint replacement. Materials and Methods: Fifteen consecutive patients underwent arthroscopy post total hip replacement. Two cases had suspected sepsis unproven by aspiration but for medical reasons were unable to undergo arthrotomy. Two cases had intraarticular migration of a broken trochanteric wire and an additional case had progressive loosening of an acetabular screw into the articulation. The remaining 10 cases had persistent and debilitating pain despite negative diagnostic studies (aspiration, arthrogram, CT, etc). Results: Two cases of joint sepsis were lavaged and debrided arthroscopically in addition to intravenous antibiotics without recurrent sepsis at 2-year follow up. Intraarticular metal fragments and a loose acetabular screw were successfully removed via arthroscopic means in 3 different hips. Ten cases had hip arthroscopy for persistent and debilitating pain despite negative radiographs and aspiration arthrogram. Findings included a loose acetabular component; corrosion at the interface of a metal-on-metal articulation; and 8 had dense scar tissue impingement at the head cup interface and synovitis. Four of those 8 had complete resolution of their symptoms, 3 went on to open arthrotomy, and one has had some improvement and chooses to decline further surgery. Discussion: Arthroscopy is not a substitute for open hip debridement and/or resection arthroplasty. However, it is of value in difficult cases to improve diagnostic accuracy. This study demonstrates successful removal of wire, beads and a bone screw by arthroscopic means, thus reducing hospital costs and patient morbidity.
TFLOPS PFS: Architecture and Design of a Highly Efficient Parallel File System

In recent years, many commercial Massively Parallel Processor (MPP) systems have been available available to the computing community. These systems provide very high processing power (up to hundreds of GFLOPs), and can scale efficiently with the number of processors. However, many scientific and commercial applications that run on these multiprocessors may not experience significant benefit in terms of speedup and are bottlenecked by their I/O requirements. Although these multiprocessors may be configured with sufficient I/O hardware, the file system software often fails to provide the available I/O bandwidth to the application, and causes severe performance performance degradation for I/O intensive applications. A highly efficient parallel file system has been implemented on Intel's Teraflops (TFLOPS) machine and provides a sustained I/O bandwidth of 1 GB/sec. This file system provides almost 95% of the available raw hardware I/O bandwidth and the I/O bandwidth scales proportional to the available I/O nodes. Intel's TFLOPS machine is the first Accelerated Strategic Computing Initiative (ASCI) machine that DOE has acquired. This computer is 10 times more powerful than the fastest machine today, and will be used primarily to simulate nuclear testing and to ensure the safety and effectiveness of the nation's nuclear weapons stockpile. This machine contains over 9000 Intel's Pentium Pro processors, and will provide a peak CPU performance of 1.8 teraflops. This papers presents the I/O design and architecture of Intel's TFLOPS supercomputer, describes the Cougar OS I/O and its interface with the Intel's Parallel File System.
Effects of electrode material on charge injection, transport, energy storage and dissipation in highly purified water

Extensive Kerr electro-optic field mapping and voltage/current measurements have been taken with highly purified water over the temperature range of T=0–30°C using parallel plane electrodes with average field strengths up to 160kV/cm. The Kerr constant of water B was measured to be B≃3.4–3.6×10−14m/V2 for free space light wavelength of 590nm and only slightly varies with temperature over the measurement range. For a step high voltage, there is no volume space charge at t=0 + . For times greater than 500µs, stainless steel and copper electrodes generally inject positive charge, although under some conditions with mixed electrodes they injected negative charge; aluminum electrodes only inject negative charge; while brass electrodes can inject either positive or negative charge. Thus, by appropriate choice of electrode material combinations and voltage polarity, it is possible to have uncharged water, unipolar charged negative or positive, or bipolar charged water. Generally, the bipolar case allows a higher applied voltage without breakdown, presumably due to the lower electric field strengths at the electrodes due to the space charge shielding. Although injected space charge increases the stared electric energy over the capacitive space charge free energy, (1/2)Cv2, for ohmic conduction the energy delivered to a resistive load is reduced because of internal dissipation in the capacitor. Volume space charge makes no contribution to the load energy but increases the dissipation in the capacitor.
CellStream — pilot customer experience

The announcement in October 1996 of BT‘s pilot CellStream asynchronous transfer mode (ATM) service marked a significant milestone in the provision of broadband services within the UK telecommunications market. Building on the success of BT‘s initial broadband Switched Multi-megabit Data Service (SMDS), CellStream provides BT‘s customers with high-speed and operationally flexible communications within the UK and internationally. This paper outlines BT‘s CellStream ATM services, and, by taking a particular example, illustrates how customers have been supported in their introduction to them.
Duration of the anti-androgen in men undergoing 6 months of an LHRH agonist and radiation therapy for unfavorable-risk prostate cancer and the risk of death

Duration of the anti-androgen in men undergoing 6 months of an LHRH agonist and radiation therapy for unfavorable-risk prostate cancer and the risk of death
A New Multi-Parameter Flow Cytometric Assay for Monitoring Lymphoma Growth and Spread in a Pre-Clinical Murine Model for Human Lymphoma.

Murine lymphoma models are commonly used to test the efficacy of idiotype-based vaccines for B-cell lymphoma prior to human trials. Mouse survival has been used as an indirect measure of the tumor response to the vaccine. In this study, we describe a multiparameter flow cytometric (MPFC) assay that enables direct assessment of the tumor at the inoculation site and detection of lymphoma metastases. In initial experiments, we show that 38C13 mouse lymphoma cells expressed an aberrant phenotype compared to normal splenocytes. The combination of CD45, CD19, B220 and an anti-idiotypic antibody (S1C5) along with a sequential gating technique defined the 38C13 cells with high sensitivity and specificity. The specificity of the MPFC assay for 38C13 lymphoma cells was greater than a gating strategy using light scatter and idiotype antibody binding. The MPFC assay was used to monitor 38C13 tumor kinetics in the C3H/HeN mouse and demonstrated tumor growth at the inoculation site and metastases to the lymph nodes and bone marrow. The presence of 38C13 metastases in lymphoid organs and bone marrow predicted by the MPFC assay were confirmed by histology and immunohistochemistry (IHC). The MPFC assay will enable investigators to monitor 38C13 lymphoma tumor response to individual vaccines or other lymphoma therapy prior to clinical trials. Furthermore, the MPFC concept could be readily applied to other models of human B cell lymphoma.
Deregulation and firm investment : evidence from the dismantling of the license system in India

This paper analyzes analyze the impact of deregulatory reforms in India during the 1990s, which eliminated compulsory industrial licensing, on manufacturing firms' investment decisions. The paper finds an economically and statistically significant positive effect of delicensing on investment. It also shows that firms in states with better credit conditions benefitted more from the removal of licenses. Moreover, the analysis demonstrates that the increase in investment was predominantly driven by smaller firms.
Sandpile groups and the coeulerian property for random directed graphs

Abstract We consider random directed graphs, and calculate the distribution of the cokernels of their laplacian, following the methods used by Wood. As a corollary, we show that the probability that a random digraph is coeulerian is asymptotically upper bounded by a constant around 0.43.
A Rational Catalan Formula for $(m,3)$-Hikita Polynomials

Hikita polynomials are the combinatorial side of the rational shuffle theorem. Building upon a recent formula for $(m,3)$-Catalan polynomials, we prove a formula for $(m,3)$-Hikita polynomials in terms of Catalan polynomials. This formula shows a surprising relation among coefficients of Hikita polynomials and implies deeper recursive relations and proves the $q,t$-symmetry of $(m,3)$-Hikita polynomials.
INSTABILITY FOLLOWING PRIMARY TKA: WOBBLE AND BUCKLE

Instability currently represents the most frequent cause for revision total knee replacement. Instability can be primary from the standpoint of inadequately performed collateral and/or posterior cruciate ligament balancing during primary total knee replacement or it may be secondary to malalignment secondary to loosening which can develop later progressive instability. Revision surgery must take into consideration any component malalignment that may have primarily contributed to instability. Care should be given to assessing collateral ligament integrity. This can be done during physical examination by manual or radiological stress testing to see if the mediolateral stress of the knee comes to a good endpoint. If there is no sense of a palpable endpoint, then the surgeon must assume structural incompetency of the medial or lateral collateral ligament or both. In posterior cruciate ligament retaining knees, anteroposterior instability must be assessed. For instability, most revisions will require a posterior cruciate substituting design or a constrained unlinked condylar design that, although sometimes a posterior cruciate ligament preserving design can be used in situations where the bone-stock is well preserved. However, if the patient displays considerable global instability, a linked, rotating platform constrained total knee replacement design will be required. Recent data has shown that the rotating hinges work quite well in restoring stability to the knee with maintenance of the clinical results over a considerable length of time. During revision surgery, laminar spreaders may be utilised to assess the flexion and extension spaces after the tibial platform is restored. If a symmetric flexion and extension space is achieved, then the collateral ligaments are intact. Depending on the remaining existing bone stock, a posterior stabilised or constrained condylar unlinked prosthesis may be used for implantation. In cases with considerable asymmetry or a large flexion/extension mismatch, then a rotating hinge design should be utilised. Intramedullary stems should be utilised in most cases when bone integrity is suspect and insufficient. Currently, stems should be placed cementless to permit easier future revision. Cementing the stems is only recommended if there is lack of intramedullary isthmic support or there is a hip prosthetic stem that prohibits a stem from engaging the isthmic cortex. However, it should be realised that later revision of the fully cemented revision implant may be quite difficult. Infection should be ruled out by aspiration off of antibiotics prior to any revision operation, especially if loosening of the components represents the cause of instability. The surgeon should attempt to restore collateral ligament balance whenever possible as this yields the best clinical result.
Genetic and pharmacologic manipulation of TLR4 has minimal impact on ethanol consumption in rodents

Toll-like receptor 4 (TLR4) is a critical component of innate immune signaling and has been implicated in alcohol responses in preclinical and clinical models. Members of the Integrative Neuroscience Initiative on Alcoholism (INIA-Neuroimmune) consortium tested the hypothesis that TLR4 mediates excessive ethanol drinking using the following models: (1) Tlr4 knock-out (KO) rats, (2) selective knockdown of Tlr4 mRNA in mouse nucleus accumbens (NAc), and (3) injection of the TLR4 antagonist (+)-naloxone in mice. Lipopolysaccharide (LPS) decreased food/water intake and body weight in ethanol-naive and ethanol-trained wild-type (WT), but not Tlr4 KO rats. There were no consistent genotypic differences in two-bottle choice chronic ethanol intake or operant self-administration in rats before or after dependence. In mice, (+)-naloxone did not decrease drinking-in-the-dark and only modestly inhibited dependence-driven consumption at the highest dose. Tlr4 knockdown in mouse NAc did not decrease drinking in the two-bottle choice continuous or intermittent access tests. However, the latency to ethanol-induced loss of righting reflex increased and the duration decreased in KO versus WT rats. In rat central amygdala neurons, deletion of Tlr4 altered GABAA receptor function, but not GABA release. Although there were no genotype differences in acute ethanol effects before or after chronic intermittent ethanol exposure, genotype differences were observed after LPS exposure. Using different species and sexes, different methods to inhibit TLR4 signaling, and different ethanol consumption tests, our comprehensive studies indicate that TLR4 may play a role in ethanol-induced sedation and GABAA receptor function, but does not regulate excessive drinking directly and would not be an effective therapeutic target. SIGNIFICANCE STATEMENT Toll-like receptor 4 (TLR4) is a key mediator of innate immune signaling and has been implicated in alcohol responses in animal models and human alcoholics. Members of the Integrative Neuroscience Initiative on Alcoholism (INIA-Neuroimmune) consortium participated in the first comprehensive study across multiple laboratories to test the hypothesis that TLR4 regulates excessive alcohol consumption in different species and different models of chronic, dependence-driven, and binge-like drinking. Although TLR4 was not a critical determinant of excessive drinking, it was important in the acute sedative effects of alcohol. Current research efforts are directed at determining which neuroimmune pathways mediate excessive alcohol drinking and these findings will help to prioritize relevant pathways and potential therapeutic targets.
Reward maximization in general dynamic matching systems

We consider a matching system with random arrivals of items of different types. The items wait in queues—one per item type—until they are “matched.” Each matching requires certain quantities of items of different types; after a matching is activated, the associated items leave the system. There exists a finite set of possible matchings, each producing a certain amount of “reward.” This model has a broad range of important applications, including assemble-to-order systems, Internet advertising, and matching web portals. We propose an optimal matching scheme in the sense that it asymptotically maximizes the long-term average matching reward, while keeping the queues stable. The scheme makes matching decisions in a specially constructed virtual system, which in turn controls decisions in the physical system. The key feature of the virtual system is that, unlike the physical one, it allows the queues to become negative. The matchings in the virtual system are controlled by an extended version of the greedy primal–dual (GPD) algorithm, which we prove to be asymptotically optimal—this in turn implies the asymptotic optimality of the entire scheme. The scheme is real time; at any time, it uses simple rules based on the current state of the virtual and physical queues. It is very robust in that it does not require any knowledge of the item arrival rates and automatically adapts to changing rates. The extended GPD algorithm and its asymptotic optimality apply to a quite general queueing network framework, not limited to matching problems, and therefore are of independent interest.
Risk and Return in Fixed-Income Arbitrage: Nickels in Front of a Steamroller?

We conduct an analysis of the risk and return characteristics of a number of widely used fixed-income arbitrage strategies. We find that the strategies requiring more ‘‘intellectual capital’’ to implement tend to produce significant alphas after controlling for bond and equity market risk factors. These positive alphas remain significant even after taking into account typical hedge fund fees. In contrast with other hedge fund strategies, many of the fixed-income arbitrage strategies produce positively skewed returns. These results suggest that there may be more economic substance to fixedincome arbitrage than simply ‘‘picking up nickels in front of a steamroller.’’ During the hedge fund crisis of 1998, market participants were given a revealing glimpse into the proprietary trading strategies used by a number of large hedge funds such as Long-Term Capital Management (LTCM). Among these strategies, few were as widely used—or as painful—as fixedincome arbitrage. Virtually every major investment banking firm on Wall Street reported losses directly related to their positions in fixed-income arbitrage during the crisis. Despite these losses, however, fixed-income arbitrage has since become one of the most popular and rapidly growing sectors within the hedge fund industry. For example, the Tremont/TASS (2005) Asset Flows Report indicates that total assets devoted to fixed-income arbitrage grew by more than $9.0 billion during 2005 and that the total
Telomeres and their synthesis.

Telomeres, the specialized DNA-protein structures found at the ends of every eukaryotic chromosome, are required to stabilize chromosomes. Telomeric DNA, comprising the extreme molecular ends of chromosomes, consists of simple tandemly repeated sequences, characterized by clusters of G residues is one strand. The enzyme telomerase is responsible for synthesis of the G-rich strand of telomeric DNA
Rare Nash Equilibria and the Price of Anarchy in Large Static Games

We study a static game played by a finite number of agents, in which agents are assigned independent and identically distributed random types and each agent minimizes its objective function by choo...
Rigorous proof of the Boltzmann-Gibbs distribution of money on connected graphs

Models in econophysics, i.e., the emerging field of statistical physics that applies the main concepts of traditional physics to economics, typically consist of large systems of economic agents who are characterized by the amount of money they have. In the simplest model, at each time step, one agent gives one dollar to another agent, with both agents being chosen independently and uniformly at random from the system. Numerical simulations of this model suggest that, at least when the number of agents and the average amount of money per agent are large, the distribution of money converges to an exponential distribution reminiscent of the Boltzmann–Gibbs distribution of energy in physics. The main objective of this paper is to give a rigorous proof of this result and show that the convergence to the exponential distribution holds more generally when the economic agents are located on the vertices of a connected graph and interact locally with their neighbors rather than globally with all the other agents. We also study a closely related model where, at each time step, agents buy with a probability proportional to the amount of money they have, and prove that in this case the limiting distribution of money is Poissonian.
Computational modeling of radiofrequency ablation: Evaluation on ex vivo data using ultrasound monitoring

Radiofrequency ablation (RFA) is the most widely used minimally invasive ablative therapy for liver cancer, but it is challenged by a lack of patient-specific monitoring. Inter-patient tissue variability and the presence of blood vessels make the prediction of the RFA difficult. A monitoring tool which can be personalized for a given patient during the intervention would be helpful to achieve a complete tumor ablation. However, the clinicians do not have access to such a tool, which results in incomplete treatment and a large number of recurrences. Computational models can simulate the phenomena and mechanisms governing this therapy. The temperature evolution as well as the resulted ablation can be modeled. When combined together with intraoperative measurements, computational modeling becomes an accurate and powerful tool to gain quantitative understanding and to enable improvements in the ongoing clinical settings. This paper shows how computational models of RFA can be evaluated using intra-operative measurements. First, simulations are used to demonstrate the feasibility of the method, which is then evaluated on two ex vivo datasets. RFA is simulated on a simplified geometry to generate realistic longitudinal temperature maps and the resulted necrosis. Computed temperatures are compared with the temperature evolution recorded using thermometers, and with temperatures monitored by ultrasound (US) in a 2D plane containing the ablation tip. Two ablations are performed on two cadaveric bovine livers, and we achieve error of 2.2 °C on average between the computed and the thermistors temperature and 1.4 °C and 2.7 °C on average between the temperature computed and monitored by US during the ablation at two different time points (t = 240 s and t = 900 s).
Direct peritoneal resuscitation improves mesenteric perfusion by nitric oxide dependent pathways.

Abstract Background Direct peritoneal resuscitation (DPR) has been shown to increase survival after intestinal ischemia and reperfusion injury (I/R). We have previously appreciated that minimum essential medium (MEM), a synthetic cell culture medium with bovine serum, glutamine, and antibiotics, contributes to these benefits. We hypothesized that (1) DPR using MEM as a dialysate would increase mesenteric perfusion, improve intestinal mucosal injury, and limit intestinal and hepatic inflammation after intestinal I/R and (2) these improvements would be dependent on endothelial nitric oxide pathways. Methods Eight-week-old C57Bl6J wild-type (WT) and eNOS Knock Out (eNOS KO) male mice were anesthetized and intestinal ischemia was induced for 60 min. After ischemia, 1 mL of phosphate buffered saline vehicle or MEM was injected into the abdominal cavity. Intestinal perfusion was reassessed after 48 h. Animals were then euthanized, and intestines and livers explanted for histologic and molecular analyses. Results DPR with MEM significantly improved mesenteric perfusion compared with vehicle (phosphate buffered saline) as measured by Laser Doppler Imaging (WT + MEM 91.58 ± 13.74%, WT + Vehicle 44.27 ± 11.93%, P 0.05). Intestinal levels of interleukin (IL)-1β were increased in WT animals treated with MEM compared with eNOS KOs, whereas concentrations of intestinal IL-6 were similar between groups. Hepatic levels of both IL-1β and IL-6 were significantly elevated in eNOS KOs compared with WT treated with MEM. Conclusions DPR with MEM has significant therapeutic potential for improving mesenteric perfusion, intestinal injury, and the local inflammatory response after intestinal I/R. These benefits appear to be dependent on nitric oxide signaling within the endothelium.
Fintech Codgers Look Back 25 Years

This article is a retrospective and prospective look at financial technology topics including high-speed markets and high-frequency trading; cyber-risk and TEOTWAWKI (“The End of the World As We Know It”); what happens when everything is indexed; impacts of artificial intelligence; and ageism in the investment industry. This piece is written by a long-time Journal of Investing fintech author, with contributions from others who have been active in financial technology over the journal’s 25-year history.
Markov decision processes with exogenous variables

I present two algorithms for solving dynamic programs with exogenous variables: endogenous value iteration and endogenous policy iteration. These algorithms are always at least as fast as relative ...
WEIGHT-BEARING CONDYLE MOTION OF THE KNEE BEFORE AND AFTER CRUCIATE-RETAINING TKA: IN-VIVO SURGICAL TRANSEPICONDYLAR AXIS AND GEOMETRIC CENTRE AXIS ANALYSES

Introduction An equal knee joint height during flexion and extension is of critical importance in optimizing soft-tissue balancing following total knee arthroplasty (TKA). However, there is a paucity of data regarding the in-vivo knee joint height behavior. This study evaluated in-vivo heights and anterior-posterior (AP) translations of the medial and lateral femoral condyles before and after a cruciate-retaining (CR)-TKA using two flexion axes: surgical transepicondylar axis (sTEA) and geometric center axis (GCA). Methods Eleven patient with advanced medial knee osteoarthritis (age: 51–73 years) who scheduled for a CR TKA and 9 knees from 8 healthy subjects (age: 23–49 years) were recruited. 3D models of the tibia and femur were created from their MR images. Dual fluoroscopic images of each knee were acquired during a weight-bearing single leg lunge. The OA knee was imaged again one year after surgery using the fluoroscopy during the same weight-bearing single leg lunge. The in vivo positions of the knee along the flexion path were determined using a 2D/3D matching technique. The GCA and sTEA were determined based on existing methods. Besides the anterior-posterior translation, the femoral condyle heights were determined using the distances from the medial and lateral epicondyle centers on the sTEA and GCA to the tibial plateau surface in coronal plane (Fig. 1). The paired t-test was applied to compare the medial and lateral condyle motion within each group (Healthy, OA, and CR-TKA). Two-way ANOVA followed post hoc Newman–Keuls test was adopted to detect significant differences among the groups. p Results The results demonstrated that following TKA, the medial and lateral femoral condyle heights were not equal at mid-flexion (15° to 45°, medial condyle lower then lateral by 2.4mm at least, p 2mm increase on average, p 90°), both condyles were significantly higher (>2mm, p Conclusion Femoral condyle heights and AP translations of the CR TKA knees were significantly different from the healthy knees during the weight bearing flexion activity when measured using both the sTEA and GCA, especially at mid-flexion (15° to 45°) and deep flexion (>90°). These results suggest that a well-balanced knee intra-operatively might not necessarily result in mid-flexion and deep flexion balance during functional weight-bearing motion, implying mid-flexion instability and deep flexion tightness of the knee. The data could be useful for improvement of future prostheses designs and surgical techniques in treatment of patients with end-stage medial knee OA.
Explaining the effect of financial development on the quality of property rights

Empirical evidence suggests that financial development can catalyze property rights reforms. This paper offers a theory of financial markets to explain these facts defining the relationship. The explanation is based on a simple trade‐off between the costs and the benefits of securing property. Securing the right to property at a cost allows agents to post collateral against loans. However, the benefits of collateral vary according to the existing credit market conditions, which we take into account in the tradeoff between the costs and the benefits of securing property rights along the path of financial development to explain the conditions under which financial development can create incentives for better property rights institutions.
Mapping smokeless powder residue on PVC pipe bomb fragments using total vaporization solid phase microextraction

Quantitating post-blast explosive residue is not a common practice in crime labs as it is typically not legally relevant. There is value in quantitation, however, if the distribution of residues on Improvised Explosive Devices (IEDs) can help guide future sample collection and/or method development. Total vaporization solid phase microextraction gas chromatography mass spectrometry (TV-SPME/GC/MS) was used to quantify residues of double-base smokeless powder (DBSP), which includes nitroglycerin (NG), diphenylamine (DPA), and ethyl centralite (EC) on post-blast PVC pipe bomb fragments. The analytical method could separate the three constituents in under 5min with a detection limit under 1ppb, which demonstrates high throughput while maintaining high sensitivity. The method was optimized for nitroglycerin, as it is the most indicative of DBSP. The average mass of nitroglycerin recovered from an entire PVC device was 1.0mg. The average mass of diphenylamine recovered was much lower (24μg) and only one device had detectable levels of EC. The typical concentration of NG on any given fragment was approximately 15-30ppm (μg NG/g fragment). However, there was no correlation between the mass of a fragment and the mass of residue upon it. Instead, the residue was distributed such that the highest concentration of residues was found on end cap fragments.
Inference of preference heterogeneity from choice data

Abstract Suppose an analyst observes inconsistent choices from either a single decision-maker, or a population of agents. Can the analyst determine whether this inconsistency arises from choice error (imperfect maximization of a single preference) or from preference heterogeneity (deliberate maximization of multiple preferences)? I model choice data as generated from imperfect maximization of a small number of preferences. The main results show that (a) simultaneously minimizing the number of inferred preferences and the number of unexplained observations can exactly recover the number of underlying preferences with high probability; (b) simultaneously minimizing the richness of the set of preferences and the number of unexplained observations can exactly recover the choice implications of the decision maker's underlying preferences with high probability.
Housing equity dynamics and home improvements

In this study, we examine the effect of housing equity position, measured using the loan-to-value (LTV) ratio, on the probability of home improvements. Using 2001–2011 data from the Panel Study of Income Dynamics (PSID), we find that a higher LTV ratio, in general, reduces the probability of home improvements. We also find that the probability of home improvements depends on the recent change of housing equity position and, more importantly, on the causes of the change. Probability of home improvements decreases more when a high LTV ratio is caused by falling house prices than when it is caused by equity extraction.
Collinear factorization violation and effective field theory

The factorization of amplitudes into hard, soft and collinear parts is known to be violated in situations where incoming particles are collinear to outgoing ones. This result was first derived by studying limits where noncollinear particles become collinear. We show that through an effective field theory framework with Glauber operators, these factorization-violating effects can be reproduced from an amplitude that is factorized before the splitting occurs. We confirm results at one loop, through single Glauber exchange, and at two loops, through double Glauber exchange. To approach the calculation, we begin by reviewing the importance of Glauber scaling for factorization. We show that for any situation where initial-state and final-state particles are not collinear, the Glauber contribution is entirely contained in the soft contribution. The contributions coming from Glauber operators are necessarily nonanalytic functions of external momentum, with the nonanalyticity arising from the rapidity regulator. The nonanalyticity is critical so that Glauber operators can both preserve factorization when it holds and produce factorization-violating effects when they are present.
A Peptide Signaling System that Rapidly Enforces Paternity in the Aedes aegypti Mosquito

Summary Female Aedes aegypti mosquitoes typically mate only once with one male in their lifetime, a behavior known as "monandry" [1]. This single mating event provisions the female with sufficient sperm to fertilize the >500 eggs she will produce during her ∼4- to 6-week lifespan in the laboratory [2]. Successful mating induces lifetime refractoriness to subsequent insemination by other males, enforcing the paternity of the first male [3–5]. Ae. aegypti mate in flight near human hosts [6], and females become refractory to remating within seconds [1, 3, 4], suggesting the existence of a rapid mechanism to prevent female remating. In this study, we implicate HP-I, an Aedes - and male-specific peptide transferred to females [7], and its cognate receptor in the female, NPYLR1 [8], in rapid enforcement of paternity. HP-I mutant males were ineffective in enforcing paternity when a second male was given access to the female within 1 hr. NPYLR1 mutant females produced mixed paternity offspring at high frequency, indicating acceptance of multiple mates. Synthetic HP-I injected into wild-type, but not NPYLR1 mutant, virgins reduced successful matings. Asian tiger mosquito ( Ae. albopictus ) HP-I peptides potently activated Ae. aegypti NPYLR1. Invasive Ae. albopictus males are known to copulate with and effectively sterilize Ae. aegypti females by causing them to reject future mates [9]. Cross-species transfer of sperm and active seminal fluid proteins including HP-I may contribute to this phenomenon. This signaling system promotes rapid paternity enforcement within Ae. aegypti but may promote local extinction in areas where they compete with Ae. albopictus .
Comparison-based Choices

A broad range of on-line behaviors are mediated by interfaces in which people make choices among sets of options. A rich and growing line of work in the behavioral sciences indicate that human choices follow not only from the utility of alternatives, but also from the choice set in which alternatives are presented. In this work we study comparison-based choice functions, a simple but surprisingly rich class of functions capable of exhibiting so-called choice-set effects. Motivated by the challenge of predicting complex choices, we study the query complexity of these functions in a variety of settings. We consider settings that allow for active queries or passive observation of a stream of queries, and give analyses both at the granularity of individuals or populations that might exhibit heterogeneous choice behavior. Our main result is that any comparison-based choice function in one dimension can be inferred as efficiently as a basic maximum or minimum choice function across many query contexts, suggesting that choice-set effects need not entail any fundamental algorithmic barriers to inference. We also introduce a class of choice functions we call distance-comparison-based functions, and briefly discuss the analysis of such functions. The framework we outline provides intriguing connections between human choice behavior and a range of questions in the theory of sorting.
The effects of gas-fluid-rock interactions on CO2 injection and storage: Insights from reactive transport modeling

Abstract Possible means of reducing atmospheric CO 2 emissions include injecting CO 2 in petroleum reservoirs for Enhanced Oil Recovery or storing CO 2 in deep saline aquifers. Large-scale injection of CO 2 into subsurface reservoirs would induce a complex interplay of multiphase flow, capillary trapping, dissolution, diffusion, convection, and chemical reactions that may have significant impacts on both short-term injection performance and long-term fate of CO 2 storage. Reactive Transport Modeling is a promising approach that can be used to predict the spatial and temporal evolution of injected CO 2 and associated gas-fluid-rock interactions. This presentation will summarize recent advances in reactive transport modeling of CO 2 storage and review key technical issues on (1) the short- and long-term behavior of injected CO 2 in geological formations; (2) the role of reservoir mineral heterogeneity on injection performance and storage security; (3) the effect of gas mixtures (e.g., H 2 S and SO 2 ) on CO 2 storage; and (4) the physical and chemical processes during potential leakage of CO 2 from the primary storage reservoir. Simulation results suggest that CO 2 trapping capacity, rate, and impact on reservoir rocks depend on primary mineral composition and injecting gas mixtures. For example, models predict that the injection of CO 2 alone or co-injection with H 2 S in both sandstone and carbonate reservoirs lead to acidified zones and mineral dissolution adjacent to the injection well, and carbonate precipitation and mineral trapping away from the well. Co-injection of CO 2 with H 2 S and in particular with SO 2 causes greater formation alteration and complex sulfur mineral (alunite, anhydrite, and pyrite) trapping, sometimes at a much faster rate than previously thought. The results from Reactive Transport Modeling provide valuable insights for analyzing and assessing the dynamic behaviors of injected CO 2 , identifying and characterizing potential storage sites, and managing injection performance and reducing costs.
Retrospective-approximation algorithms for the multidimensional stochastic root-finding problem

The stochastic root-finding problem (SRFP) is that of solving a nonlinear system of equations using only a simulation that provides estimates of the functions at requested points. Equivalently, SRFPs seek locations where an unknown vector function attains a given target using only a simulation capable of providing estimates of the function. SRFPs find application in a wide variety of physical settings.We develop a family of retrospective-approximation (RA) algorithms called Bounding RA that efficiently solves a certain class of multidimensional SRFPs. During each iteration, Bounding RA generates and solves a sample-path problem by identifying a polytope of stipulated diameter, with an image that bounds the given target to within stipulated tolerance. Across iterations, the stipulations become increasingly stringent, resulting in a sequence of shrinking polytopes that approach the correct solution.Efficiency results from: (i) the RA structure, (ii) the idea of using bounding polytopes to exploit problem structure, and (iii) careful step-size and direction choice during algorithm evolution. Bounding RA has good finite-time performance that is robust with respect to the location of the initial solution, and algorithm parameter values. Empirical tests suggest that Bounding RA outperforms Simultaneous Perturbation Stochastic Approximation (SPSA), which is arguably the best-known algorithm for solving SRFPs.
Environmental Hazards and Mortgage Credit Risk: Evidence from Texas Pipeline Incidents

This study examines the effects of pipeline hazards on credit access using evidence from the 2005–2011 home mortgage loans in Texas. Difference-in-difference analyses show a permanently lower origination rate by 1.9% in the pipeline-present areas compared to the pipeline-free areas, which was further enlarged by 1.8% whenever pipeline incidents happened. Evidence suggests that the permanent difference in credit access reflects lenders’ concerns about collateral value and borrowers’ repayment ability. The elevated post-incident risk perceptions indicate lenders’ aversion to environmental liabilities. Lenders’ risk management strategies differed by borrowers’ income and evolved with the tightening of the securitization market. This article is protected by copyright. All rights reserved
Active Metamaterial Diffraction Grating

We design and test a switchable diffraction grating based on active metamaterials for terahertz modulation. We observe off-axis diffraction which permits operation of the device as a narrowband high-contrast modulator.
Audit firms face downward-sloping demand curves and the audit market is far from perfectly competitive

We discuss the discrete choice demand estimation methods applied by Guo et al. (2017) in the audit setting. We then review insights into audit market competition that demand estimation has already provided. We conclude that the audit market is far from perfectly competitive.
Chromosome arm‐specific patterns of polymorphism associated with chromosomal inversions in the major African malaria vector, Anopheles funestus

Chromosomal inversions facilitate local adaptation of beneficial mutations and modulate genetic polymorphism, but the extent of their effects within the genome is still insufficiently understood. The genome of Anopheles funestus, a malaria mosquito endemic to sub-Saharan Africa, contains an impressive number of paracentric polymorphic inversions, which are unevenly distributed among chromosomes and provide an excellent framework for investigating the genomic impacts of chromosomal rearrangements. Here we present results of a fine-scale analysis of genetic variation within the genome of two weakly differentiated populations of Anopheles funestus inhabiting contrasting moisture conditions in Cameroon. Using population genomic analyses, we found that genetic divergence between the two populations is centered on regions of the genome corresponding to three inversions, which are characterized by high values of FST, absolute sequence divergence and fixed differences. Importantly, in contrast to the 2L chromosome arm, which is collinear, nucleotide diversity is significantly reduced along the entire length of three autosome arms bearing multiple overlapping chromosomal rearrangements. These findings support the idea that interactions between reduced recombination and natural selection within inversions contribute to sculpt nucleotide polymorphism across chromosomes in An. funestus. This article is protected by copyright. All rights reserved.
Green certification, heterogeneous producers, and green consumers: a welfare analysis of environmental regulations

We develop a vertical differentiation model to analyze welfare implications of environmental policies in a competitive market with production and consumption heterogeneity. Consumers with heterogeneous preferences choose between non-green and certified green products, while producers with heterogeneous production costs decide whether to engage in green production. In order for green products to be recognized by consumers, producers must join a green club. Key findings are summarized as follows. (i) The number of green producers, environmental standard, and overall welfare under the market solution are all socially sub-optimal. (ii) The introduction of a subsidy policy for greener production and standards is shown to increase social welfare, but is not Pareto optimal. (iii) A dual policy, which combines abatement subsidizes for a greener production standard and a tax charge for green certification, is shown to be the Pareto-optimal outcome.
Optimal Control of Multi-Stage Discrete Event Systems With Real-Time Constraints

We consider discrete event systems involving tasks with real-time constraints and seek to control processing times so as to minimize a cost function subject to each task meeting its own constraint. When tasks are processed over a single stage, it has been shown that there are structural properties of the optimal state trajectory that lead to very efficient solutions of such problems. When tasks are processed over multiple stages and are subject to end-to-end real-time constraints, these properties no longer hold and no obvious extensions are known. We consider such a multi-stage problem with not only stage-dependent but also task-dependent cost functions over all tasks at each stage and derive several new optimality properties. These properties lead to the idea of introducing ldquovirtualrdquo deadlines at each stage except the last one, thus partially decoupling the stages so that the known efficient solutions for single-stage problems can be used. We prove that a sequence of solutions to single-stage problems with virtual deadlines updated at each step converges to the global optimal solution of the multi-stage problem. This leads to a virtual deadline algorithm (VDA) which is scalable in the number of processed tasks. We illustrate the scalability and efficiency of the VDA through numerical examples.
Identification and generalizability in accounting research: A discussion of Christensen, Floyd, Liu, and Maffett (2017)

Abstract Christensen et al. (2017) provide evidence that the dissemination of mine safety information in SEC filings has real effects on mine safety. We discuss the extent to which Christensen et al.’s results generalize to a research question that we consider of broader interest to accounting researchers, specifically where and when mandated disclosure in SEC filings can increase the dissemination of information. We also discuss identification of causal effects and generalizability concerns more broadly in the context of large sample studies and quasi-natural experiments, as well as potential ways authors might address these concerns in accounting research.