Miracle-dz/UniFAR-FTUs huggingface dataset:
The Weekend Effect in Equity Option Returns ∗

We find that returns on options on individual equities display markedly lower returns over weekends (Friday close to Monday close) relative to any other day of the week. These patterns are observed both in unhedged and delta-hedged positions, indicating that the effect is not the result of a weekend effect in the underlying securities. Our results hold for puts and calls over a wide range of maturities and strike prices and remains strong in samples that include only the most liquid options. We find no evidence of a weekly seasonal in bid-ask spreads, trading volume, or open interest that could drive the effect. We also do not find evidence that weekend returns are significantly risker than weekday returns, though the weekend effect does appear stronger when the riskiness of the market portfolio is high. Weekend returns are lower when the TED spread and market volatility are high, suggesting that limits to arbitrage may explain the persistence of the effect. ∗We are grateful for comments from Mike Chernov, Larry Harris, Robert Hudson, Nikunj Kapadia, Oguz Ozbas, Yigal Newman, Nick Polson, Allen Poteshman, Eric Renault, Mark Weinstein, Fernando Zapatero, and seminar participants at USC, Hebrew University, the 2009 Montreal Financial Econometrics Conference, the 2009 Financial Management Association meetings, and the 2010 American Finance Association meetings. Shemesh thanks the Sanger Chair of Banking and Risk Management for financial support.
Ceramics and Society in Northern Europe

Neolithic pottery in Britain and Ireland was produced from shortly after 4000 BC. There are regional variations but overall a four phase chronology for the pottery is also suggested: First Neolithic, approximately 4000–3800 BC; Early Neolithic, approximately 3800–3500 BC; Middle Neolithic, approximately 3500–2900 BC; and Late Neolithic, approximately 2900–2400 BC. Within this framework evidence for the processes of pottery production and use are studied to define a number of different traditions and practices. The external form of vessels seems to be strongly codified in the early part of the period, although there was a range of different inclusion recipes used. In the Middle and Later Neolithic there seem to be much simpler fabrics but a greater range of vessel shapes. This later pottery also seems to have been used for a much wider range of tasks.
LONG-LIVED MAGNETIC-TENSION-DRIVEN MODES IN A MOLECULAR CLOUD

We calculate and analyze the longevity of magnetohydrodynamic (MHD) wave modes that occur in the plane of a magnetic thin sheet. Initial turbulent conditions applied to a magnetically subcritical cloud are shown to lead to relatively rapid energy decay if ambipolar diffusion is introduced at a level corresponding to partial ionization primarily by cosmic rays. However, in the flux-freezing limit, as may be applicable to photoionized molecular cloud envelopes, the turbulence persists at “nonlinear” levels in comparison with the isothermal sound speed cs, with one-dimensional rms material motions in the range of ≈ 2 cs–5 cs for cloud sizes in the range of ≈ 2 pc–16 pc. These fluctuations persist indefinitely, maintaining a significant portion of the initial turbulent kinetic energy. We find the analytic explanation for these persistent fluctuations. They are magnetic-tension-driven modes associated with the interaction of the sheet with the external magnetic field. The phase speed of such modes is quite large, allowing residual motions to persist without dissipation in the flux-freezing limit, even as they are nonlinear with respect to the sound speed. We speculate that long-lived large-scale MHD modes such as these may provide the key to understanding observed supersonic motions in molecular clouds.
INGRID: A near-infrared camera for the William Herschel Telescope

Rapid developments in near-infrared (NIR) arrays and adaptive optics systems have driven the development of wide-field and high-spatial-resolution, high-optical-quality NIR imagers and spectrographs, providing an unparalleled boost to NIR observations. Based around a 1024 × 1024 pixel 2 Hawaii-1 array, the Isaac Newton Group Red Imaging Device (INGRID) imager provides a field of view >16 arcmin 2 (at the Cassegrain focus) whilst Nyquist sampling the median summer seeing disc. When used in conjunction with the Nasmyth Adaptive Optics for Multi-Purpose Instrumentation (NAOMI) system and a second set of collimation optics, a high spatial resolution mode (0.04 arcsec pixel −1 ) is offered, providing near-diffractionlimited imaging. INGRID uses an all-refractive design and employs a cold stop to reduce thermal background emission, critical to the performance as it is used on the non-infrared optimized 4.2-m William Herschel Telescope (WHT). We discuss the design and operation of INGRID and illustrate its performance by discussing commissioning observations of the cluster Abell 2218 and the spiral galaxies NGC 3351 and 1530.
‘Phase diagram’ of interfacial instabilities in a two-layer Couette flow and mechanism of the long-wave instability

A unified view is given of the instabilities that may develop in two-layer Couette flows, as a ‘phase diagram’ in the parameter space. This view is obtained from a preliminary study of the single-fluid Couette flow over a wavy bottom, which reveals three flow regimes for the disturbances created at the bottom, each regime being characterized by a typical penetration depth of the vorticity disturbances and an effective Reynolds number. It appears that the two-layer flow exhibits the same flow regimes for the disturbances induced by the perturbed interface, and that each type of instability can be associated with a flow regime. Typical curves giving the growth rate versus wavenumber are deduced from this analysis, and favourably compared with the existing literature. In the second part of this study, we propose a mechanism for the long wavelength instability, and provide simple estimates of the wave velocity and growth rate, for channel flows and for semi-bounded flows. In particular, an explanation is given for the ‘thin-layer effect’, which is typical of multi-layer flows such as pressure driven flows or gravity driven flows, and according to which the flow is stable if the thinner layer is the less viscous, and unstable otherwise.
Effects in Blended Classes That Utilize Clickers to Deepen Understanding of Information Technology

In a blended lecture centering on exercises the students were asked to solve problems on paper, provided with explanatory materials, further explanations made using slides, and then asked to reply the degree of their understanding using clickers. They were also asked to reply answers of some problems using the clickers, and to reply with clickers when attendance was checked at the beginning of class. Questionnaire surveys were then carried out both before and after the class to identify how much the degree of recognition and attitude of the students had changed in the classes that utilized the clickers. Overall degree of term recognition was improved, and the overall amount of knowledge increased. Overall attitude related to abilities improved. It was achieved through various activities to deepen understanding of information technology.
Modeling regional transportation demand in China and the impacts of a national carbon constraint

Climate and energy policy in China will have important and uneven impacts on the country’s regionally heterogeneous transport system. In order to simulate these impacts, transport sector detail is added to a multi-sector, static, global computable general equilibrium (CGE) model which resolves China’s provinces as distinct regions. This framework is used to perform an analysis of national-level greenhouse gas (GHG) policies. Freight, commercial passenger and household (private vehicle) transport are separately represented, with the former two categories further disaggregated into road and non-road modes. The preparation of model inputs is described, including assembly of a provincial transport data set from publicly-available statistics. Two policies are analyzed: the first represents China’s target of a 17% reduction in GHG emissions intensity of GDP during the Twelfth Five Year Plan (12FYP), and the second China’s Copenhagen target of a 40–45% reduction in the same quantity during the period 2005–2020. We find significant heterogeneity in regional transport impacts. We find that both freight and passenger transportation in some of the poorest provinces that rely heavily on energy-intensive resource and raw materials exports are most adversely affected, as they offer many of the least cost abatement opportunities and the transformation of their energy systems strongly affects transport demand. At the national level, we find that of all the transport-related sectors, road freight transport activity is affected most by policy, likely due to its high energy intensity and limited low cost opportunities for improving efficiency. The type and degree of regional disparity in impacts is relevant to central and provincial government decisions which set and allocate climate, energy and transport policy targets. We describe how this research establishes a basis for further regional CGE analyses of the economic, energy and environmental impacts of transport-focused policies including vehicle ownership restrictions, taxation of driving activity or fuels, and the supply of public transit. ∗MIT Joint Program on the Science & Policy of Global Change, Cambridge, MA, USA 02139. †Corresponding author. E-mail: pnk@MIT.EDU. ‡Institute of Energy, Environment & Economy, Tsinghua University, Beijing, P.R. China 100084. 1
Considerations about reward mechanisms and maintaining the functional nature of tonal music

Abstract From the end of the 1990s, several studies based on imaging evidenced the participation of reward mechanisms in the hearing of tonal music. Tonal music is constructed from a set of discrete elements (musical notes) organized in time according to mathematical reasons and well-defined structural relationships, thus enabling, through the repetition of listening, the apprehension of the rules of construction and, consequently, the formation of expectations. Reward mechanisms correspond to systems which are responsive to expectations, comprising three components, formed by partially dissociable neural substrates, related to motivation, learning and hedonia. This paper seeks connections between the characteristics of tonal musical structure and material and the process of musical apprehension and activation of reward systems, suggesting the important role of such mechanisms in maintaining the longevity of tonal music in modern society, particularly in relation to its functional nature.
Nekton use of Ruppia maritima and non-vegetated bottom habitat types within brackish marsh ponds

Nekton (fishes and decapod crustaceans) use of brackish submerged aquatic vegetation (SAV) habitat has been largely overlooked in comparison to fresh and marine SAV habitats. This study was designed to examine nekton use of brackish marsh SAV habitat and non-vegetated bottom. Specifically, we examined the effects of habitat location (defined by SAV distance from marsh edge) and complexity (defined by SAV biomass) on nekton community density, biomass, and diversity in shallow water brackish marsh ponds, which contained monospecific beds of Ruppia maritima L. Three habitat types were investigated: (1) inner-pond SAV (SAV habitat > 1 m from marsh edge), (2) near marsh-edge SAV (SAV habitat < 1 m from marsh edge), and (3) non-vegetated bottom. We tested the null hypotheses that nekton density, biomass, and diversity were unrelated to habitat type or habitat characteristics. Ninety-six quantitative samples were taken with a 1 m 2 throw trap between September 2001 and July 2002. Using multivariate analysis of variance (MANOVA), a significant habitat type by season interaction was found (Wilks' λ = 0.32, F24, 259 = 4.21, p < 0.0001) for nekton density, biomass, and diversity. Simple linear regression showed a positive relationship between SAV and nekton biomass (p < 0.0001); however, distance of the vegetated habitat from the marsh edge did not significantly influence SAV or nekton biomass. SAV biomass, but not location, appears to be a dominant factor that influences nekton use within these small brackish marsh ponds. This study highlights some of the intricacies associated with the identification and use of broad scale habitat classification for management purposes. Although brackish marsh SAV habitat types support higher densities of nekton compared to non-vegetated habitat, variation within this gross classifica- tion indicates a wide range of habitat 'value' that needs to be considered for management purposes.
Helminth Parasites of Sea Otters (Enhydra lutris} from Prince William Sound, Alaska: Comparisons with Other Populations of Sea Otters and Comments on the Origin of Their Parasites

The helminths found in the gastrointestinal tracts and gallbladders of 68 sea otters (Enhydra lutris) from Prince William Sound, Alaska, and their prevalences were: Corynosoma enhydri (Acanthocephala), intes- tine, 51.5%; Orthosplanchnus fraterculus (Trematoda), gallbladder, 50%; Diplogonoporus tetrapterus (Cestoda), intestine, 12%; and Pseudoterranova decipiens (Nematoda), stomach, 1.5%. One pup examined was free of helminth parasites. Throughout its range from the Kuril and Komandorski islands in Russia, across the Aleutian Islands, Alaska, and south to California, the sea otter harbors a total of 17 or 18 species of helminths, of which 5 or 6 are incidental infections with larval (2 species of Anisakis) or juvenile worms (3 or 4 species of Poly- morphus). The adult worms of sea otters (12 species) are derived primarily (9 species) from pinnipeds. One species, Microphallus pirum (Trematoda), found widely in sea otters from the Komandorski Islands to California, may be primarily a parasite of various shorebirds. Only one species, C. enhydri, is uniquely a parasite of sea otters, occurring throughout its range at prevalences greater than 50%. California populations of sea otters harbor only M. pirum, C. enhydri, and Polymorphus species, lacking any species known to be transmitted by fish; the diet of these sea otters consists almost entirely of invertebrates. Northern sea otter populations from Russia and Alaska have a more varied diet and are hosts for at least 5 fish-transmitted parasites. Among the commonly occurring parasites, the most striking difference between Russian and Alaskan populations of sea otters is the absence of O. fraterculus from Russian populations and its frequent occurrence in Alaskan populations.
COXETER GROUPS, IMAGINARY CONES AND DOMINANCE

Brink and Howlett [Math. Ann. 296:1 (1993), 179‐190] have introduced a partial ordering, called dominance, on the root systems of Coxeter groups in their proof that all finitely generated Coxeter groups are automatic. Edgar (Ph.D. thesis, 2009), in an investigation of various regularity properties of Coxeter groups, studied a function on the reflections of such groups, called 1-height. Here we show that these two concepts are closely related to each other. We also give applications of dominance to the study of imaginary cones of Coxeter groups.
The Response of Firms' Leverage to Risk: Evidence from UK Public Versus Nonpublic Manufacturing Firms

This paper empirically investigates the effects of macroeconomic and firm-specific risk on firms' leverage. The analysis is carried out for a large panel of public and non-public UK manufacturing firms over the period 1999-2008. Our investigation provides evidence that UK manufacturing firms use less short-term debt during periods of high risk. However, the leverage of non-public manufacturing firms is more sensitive to firm-specific risk in comparison to their public counterparts while macroeconomic risk affects both types of firms similarly. Our investigation also shows that firms with high liquid assets reduce their leverage more (less) during periods of heightened firm-specific (macroeconomic) risk.
CSR activities in the German poultry sector: differencing preference groups

Corporate Social Responsibility (CSR) has long been an issue worldwide, and more and more industries are taking note. One important example is the poultry industry in Germany, which has become a focal point of public debate. Increasingly, consumers are demanding that firms take responsibility for their corporate actions. The goals of this study were, first, to analyze consumers’ preferences for poultry firms’ CSR commitment with the help of an adaptive conjoint analysis. Second, a cluster analysis is set out to define consumer groups according to their preferences. With regard to CSR, consumers in this study were most concerned with product quality, animal welfare and employee issues. TV, newspaper and product packaging are their most preferred information sources. Three clusters were identified. Firms should focus more on communicating what their firm’s commitment comprises and should adapt their CSR activities and firm communication methods to the preferences of different target groups.
Analysis of Organizational Factors that D etermine Turnover Intention

The present study sought to examine the mediating role of organizational trust in the relationship between perceived organizational support, perception of personnel management policies and practices, and turnover intentions. The sample consisted of 250 employees, predominantly women (60.8%), with a mean age of 28 years and an average length of employment of 2.8 years. Most of them was employed in private companies (89.25%) and presented incomplete higher education (60.4%). The data was analyzed through descriptive statistics and path analysis (Structural Equations Modeling) so as to appraise the mediation relationships and indirect effects between the variables, analyzing which of them represent direct or indirect predictors of turnover intentions. The results indicated that the proposed model was only partially corroborated, given that the mediation relationships were partial and the indirect effects were not signifi cative. We recommend further studies involving both other samples and the inclusion of other variables in the research models.
Edinburgh Research Explorer Transmission of non-B HIV subtypes in the UK is increasingly driven by large non-heterosexual clusters

Background . The United Kingdom human immunode ﬁ ciency virus (HIV) epidemic was historically dominated by HIV subtype B transmission among men who have sex with men (MSM). Now 50% of diagnoses and prevalent infections are among heterosexual individuals and mainly involve non-B subtypes. Between 2002 and 2010, the prevalence of non-B diagnoses among MSM increased from 5.4% to 17%, and this study focused on the drivers of this change. Methods . Growth between 2007 and 2009 in transmission clusters among 14 000 subtype A1, C, D, and G sequences from the United Kingdom HIV Drug Resistance Database was analysed by risk group. Results . Of 1148 clusters containing at least 2 sequences in 2007, >75% were pairs and >90% were heterosexual. Most clusters (71.4%) did not grow during the study period. Growth was signi ﬁ cantly lower for small clusters and higher for clusters of ≥ 7 sequences, with the highest growth observed for clusters comprising sequences from MSM and people who inject drugs (PWID). Risk group ( P < .0001), cluster size ( P < .0001), and subtype ( P < .01) were predictive of growth in a generalized linear model. Discussion . Despite the increase in non-B subtypes associated with heterosexual transmission, MSM and PWID are at risk for non-B infections. Crossover of subtype C from heterosexuals to MSM has led to the expansion of this subtype within
What Can Ex-Participants Reveal about a Program’s Impact?

We propose a method for estimating the mean impact of an assigned social program when it is not feasible to do a pre-intervention baseline survey but it is feasible to track ex-participants. In our triple-difference estimator, measured outcome changes are compared between continuing participants and matched ex-participants, after netting out the outcome changes for a matched comparison group who never participated. With sufficient followup observations one can test the joint conditions required for correctly identifying the gains to current participants. We apply the method to a workfare program in Argentina. Significant impacts on participants’ current incomes are revealed.
Genital Candida in Patients with Sexually Transmitted Infections Ã¢ÂÂAn Innocent Bystander or a Pathogenic Culprit?.

The presence of one STI increases the risk of having concomitant and co-transmission of other STI. An evolving trend of Candida infections in STI patients, showing a transition from harmless colonizers to unrelenting pathogens, is a fine line attributable to extensive repertoire of virulence determinants. The present study was carried out to identify the genital Candida flora prevalent in patients attending sexually transmitted disease (STD) Clinic and to determine the haemolysin and phospholipase activity amongst these isolates. Further, correlation of species of infecting/ prevalent Candida with the co-existing STI was done. A total of 75 consecutive male and female patients, presenting with one or more of the complaints as enunciated by World Health Organization (WHO) in the Syndromic Approach for the diagnosis of STIs, were included in the study. Candida was isolated in significantly higher numbers from patients presenting with discharge (47%) followed by balanitis (30%), and genital ulcer (23%). C. albicans (73%) was predominant isolate in various STIs. Hemolysin index and phospholipase activity of C. albicans was found significantly higher enhancing their pathogenic potential. The study suggests the role of genital inflammation by Candida as a significant cofactor in STI acquisition and existence of genital Candida as colonizer or pathogen. The study provides a rational basis for empirical therapy in STI patients.
EFFECTS OF CRUDE OIL AS A SOIL CONTAMINANT ON SEEDLING GROWTH OF JATROPHA CURCAS L.

A study was conducted in 2010 to evaluate the effects of crude oil as a soil contaminant on the performance of Jatropha curcasseedlings in Asaba, Delta State, Nigeria. Oil concentrations used were 0.0, 2.0, 4.0, 6.0, 8.0 and 10.0% w/w . The experiment was arranged in a randomized complete block design with four replicates and monitored for 10 weeks after transplanting. The results showed that contamination of soil with crude oil significantly reduced (P ￻≥0.05) the performance ofJatropha curcasseedlings as regards plant height, number of leaves, leaf area and collar diameter when compared with seedlings grown in the uncontaminated soils. The performance of the seedlings was oil concentration dependent. Other symptoms observed at the hig her levels of oil treatments were yellowness of leaves, leaf fall/drop, chlorosis, growth retardation and stagnation as well as wilting. This study has shown that crude oil in soil has a highly significant effect of reducing the performance of J. curcasseedlings. The oil level most tolerated by the plant is 2.0% w/w and above this level, significant reductions were recorded. This study has great implications on the sustainability of this multipurpose species, which has been identified as a potential biofue l species.