HOMFLY polynomials, stable pairs and motivic Donaldson-Thomas invariants

Hilbert scheme topological invariants of plane curve singularities are identified to framed threefold stable pair invariants. As a result, the conjecture of Oblomkov and Shende on HOMFLY polynomials of links of plane curve singularities is given a Calabi-Yau threefold interpretation. The motivic Donaldson-Thomas theory developed by M. Kontsevich and the third author then yields natural motivic invariants for algebraic knots. This construction is motivated by previous work of V. Shende, C. Vafa and the first author on the large $N$ duality derivation of the above conjecture.Comment: 59 pages; v2 references added, minor corrections; v3: exposition improved, proofs expanded, results unchanged, to appear in Comm. Num. Th. Phy

Confirmation of the 62 Day X-Ray Periodicity from M82

Using 400 days of new X-ray monitoring of M82, we confirm the 62 day periodicity previously reported. In the full data set spanning 1124 days, we find a period of 62.0 +/- 0.3 days and a coherence, Q = 22.3, that is consistent with a strictly periodic signal. We estimate that the probability of chance occurrence of our observed signal is 6E-7. The light curve folded at this period is roughly sinusoidal and has a peak to peak amplitude of (0.99 +/- 0.10) x 10^-11 erg cm^-2 s^-1. Confirmation of the periodicity strengthens our previous suggestion that the 62 day modulation is due to orbital motion within an X-ray binary.Comment: 4 pages, to appear in Ap

Compton backscattered annihilation line emission: A new diagnostic of accreting compact sources

It is shown that Compton scattering of 511 keV electron-positron annihilation radiation produces a line like feature at approx. 170 keV from backscattered photons. Assuming a simple model of an accretion disk around a compact source, the spectrum is explored of the spectrum of Compton scattered annihilation line emission for a range of conditions. It is further shown that such Compton baskscattering of annihilation line emission from the inner edge of an accretion disk could account for the previously unidentified 170 keV line emission and high energy continuum observed from a variable, compact source, or sources, of annihilation radiation near the Galactic Center. Identification of the observed 170 keV line as an annihilation line reflection feature provides strong new evidence that the source of the emission is an accreting compact object. Further study of these features in existing spectra and in forthcoming GRO observation of these and other sources can provide unique new diagnostics of the innermost regions of accretion disks around compact objects

Digital learning objects: a local response to the California State University system initiative

The purpose of this paper is to present a virtual library plan created by library directors of the 23 California State University (CSU) system campuses. The information literacy portion of the project offers a repository of high quality interactive digital learning objects (DLOs) in the MERLOT repository. Therefore, DLOs created locally at the Dr Martin Luther King, Jr Library at San José State University (SJSU) focus on topics that supplement the “core” DLO collection

Outcomes of Physicians' Communication Goals During Patient Interactions.

During healthcare visits, physicians may set communication goals such as providing their patient with information about treatment; however, no recommendations exist regarding which goals physicians should prioritize during their often-brief interactions with patients. Two studies examined five communication goals (providing information, reducing distress, increasing patient satisfaction, increasing patient adherence, and encouraging hope) in the context of physician-patient interactions and their relationship with patient and physician outcomes. In Study 1, audio-recordings of physician-patient interactions were coded by research assistants for goal-related content. In Study 2, patients reported their physician's use of each goal during the interaction. In both studies, patients and physicians reported visit outcomes. Within-study meta-analyses suggested that the goal of reducing distress, but not the other goals, was consistently related to improved outcomes in Study 1. All goals were related to improved outcomes in Study 2. We then computed sample-size-weighted meta-analytic effects of each goal on each outcome across both studies. These results suggested that all of the goals had similar-sized positive relationships with patient and physician outcomes across studies. These findings suggest that physicians should generally approach consultations with communication goals in mind, but prioritizing efforts to reduce distress may be particularly beneficial

Policy reform and farmers' wheat allocation in rural China: a case study

Market-oriented policy reforms often have important effects on farm-level grain production and utilisation decisions in developing countries. China’s grain farmers are of particular interest because of China’s importance in world grain markets and because of China’s recent major agricultural policy advances and retrenchments. An empirical evaluation of market liberalisation among farmers located in two provinces in China on farm-level wheat consumption, market sales and on-farm storage during 1994 is presented. The results indicate that policymakers should account for such changes in farm household behaviour in designing and assessing the consequence ofmarket liberalisation programs for agricultural sectors in developing countries.China, grain storage, household allocation decisions, procurement quotas, wheat, Crop Production/Industries,

Are foreign investors attracted to weak environmental regulations? Evaluating the evidence from China

One of the most contentious debates today is whether pollution-intensive industries from rich countries relocate to poor countries with weaker environmental standards, turning them into pollution havens. Empirical studies to date show little evidence to support the pollution haven hypothesis, but suffer potentially from omitted variable bias, specification, and measurement errors. The authors estimate the strength of pollution-haven behavior by examining the location choices of equity joint venture (EJV) projects in China. They derive a location choice model from a theoretical framework that incorporates the firm's production and abatement decision, agglomeration, and factor abundance. The authors estimate conditional logit and nested logit models using new data sets containing information on a sample of EJV projects, effective environmental levies on water pollution, and estimates of Chinese pollution-intensity for 3-digit ISIC (International Standard Industrial Classification) industries. Results from 2,886 manufacturing joint venture projects from 1993-96 show that EJVs from all source countries go into provinces with high concentrations of foreign investment, relatively abundant stocks of skilled workers, concentrations of potential local suppliers, special incentives, and less state ownership. Environmental stringency does affect location choice, but not as expected. Low environmental levies are a significant attraction only for joint ventures in highly-polluting industries with partners from Hong Kong, Macao, and Taiwan (China). In contrast, joint ventures with partners from OECD sources are not attracted by low environmental levies, regardless of the pollution intensity of the industry. The authors discuss the likely role of technological differences in explaining these results.Environmental Economics&Policies,Economic Theory&Research,Water and Industry,Decentralization,Public Health Promotion,Environmental Economics&Policies,Water and Industry,Economic Theory&Research,Health Monitoring&Evaluation,ICT Policy and Strategies