Volatility dynamics of nymex natural gas futures prices

Despite their importance in pricing futures and other derivative contracts, seasonalvariations in mean and variance of energy prices have not been fully captured inprevious studies of energy prices. We examine the volatility dynamics of daily naturalgas futures traded on the NYMEX via the partially overlapping time-series (POTS) modelof Smith (2005, Journal of Applied Econometrics). We illustrate that the volatility of dailyprice changes of natural gas exhibits strong seasonality, even as the volatility increases asa contract approaches its expiration, a time-to-maturity effect. Our analysis reveals thatthe persistence of price shocks and, hence, the correlations among concurrently tradedcontracts, also exhibit substantial seasonal and cross-sectional variation. These volatilitypatterns we estimate are closely related to the seasonal cycle of US natural gas storage ina way consistent with the theory of storage. We demonstrate that, by ignoring theseasonality in the volatility dynamics of natural gas futures prices, previous studies havesuggested sub-optimal hedging strategies

Self-field effects upon the critical current density of flat superconducting strips

We develop a general theory to account self-consistently for self-field effects upon the average transport critical current density Jc of a flat type-II superconducting strip in the mixed state when the bulk pinning is characterized by a field-dependent depinning critical current density Jp(B), where B is the local magnetic flux density. We first consider the possibility of both bulk and edge-pinning contributions but conclude that bulk pinning dominates over geometrical edge-barrier effects in state-of-the-art YBCO films and prototype second-generation coated conductors. We apply our theory using the Kim model, JpK(B) = JpK(0)/(1+|B|/B0), as an example. We calculate Jc(Ba) as a function of a perpendicular applied magnetic induction Ba and show how Jc(Ba) is related to JpK(B). We find that Jc(Ba) is very nearly equal to JpK(Ba) when Ba > Ba*, where Ba* is the value of Ba that makes the net flux density zero at the strip's edge. However, Jc(Ba) is suppressed relative to JpK(Ba) at low fields when Ba < Ba*, with the largest suppression occurring when Ba*/B0 is of order unity or larger.Comment: 9 pages, 4 figures, minor revisions to add four reference

Structural Insights into Differences in Drug-binding Selectivity between Two Forms of Human α1-Acid Glycoprotein Genetic Variants, the A and F1*S Forms

Human α1-acid glycoprotein (hAGP) in serum functions as a carrier of basic drugs. In most individuals, hAGP exists as a mixture of two genetic variants, the F1*S and A variants, which bind drugs with different selectivities. We prepared a mutant of the A variant, C149R, and showed that its drug-binding properties were indistinguishable from those of the wild type. In this study, we determined the crystal structures of this mutant hAGP alone and complexed with disopyramide (DSP), amitriptyline (AMT), and the nonspecific drug chlorpromazine (CPZ). The crystal structures revealed that the drug-binding pocket on the A variant is located within an eight-stranded β-barrel, similar to that found in the F1*S variant and other lipocalin family proteins. However, the binding region of the A variant is narrower than that of the F1*S variant. In the crystal structures of complexes with DSP and AMT, the two aromatic rings of each drug interact with Phe-49 and Phe-112 at the bottom of the binding pocket. Although the structure of CPZ is similar to those of DSP and AMT, its fused aromatic ring system, which is extended in length by the addition of a chlorine atom, appears to dictate an alternative mode of binding, which explains its nonselective binding to the F1*S and A variant hAGPs. Modeling experiments based on the co-crystal structures suggest that, in complexes of DSP, AMT, or CPZ with the F1*S variant, Phe-114 sterically hinders interactions with DSP and AMT, but not CPZ. © 2011 by The American Society for Biochemistry and Molecular Biology, Inc

1 um Excess Sources in the UKIDSS - I. Three T Dwarfs in the SDSS Southern Equatorial Stripe

We report the discovery of two field brown dwarfs, ULAS J0128-0041 and ULAS J0321+0051, and the rediscovery of ULAS J0226+0051 (IfA 0230-Z1), in the Sloan Digital Sky Survey (SDSS) southern equatorial stripe. They are found in the course of our follow-up observation program of 1 um excess sources in the United Kingdom Infrared Telescope Infrared Deep Sky Survey. The Gemini Multi-Object Spectrographs spectra at red optical wavelengths (6500-10500 A) are presented, which reveal that they are early-T dwarfs. The classification is also supported by their optical to near-infrared colors. It is noted that ULAS J0321+0051 is one of the faintest currently known T dwarfs. The estimated distances to the three objects are 50-110 pc, thus they are among the most distant field T dwarfs known. Dense temporal coverage of the target fields achieved by the SDSS-II Supernova Survey allows us to perform a simple time-series analysis, which leads to the finding of significant proper motions of 150-290 mas/yr or the transverse velocities of 40-100 km/s for ULAS J0128-0041 and ULAS J0226+0051. We also find that there are no detectable, long-term (a-few-year) brightness variations above a few times 0.1 mag for the two brown dwarfs.Comment: Accepted for publication in the Astronomical Journal; Typos correcte

Comparative Bioavailability Of Two Quetiapine Formulations In Healthy Volunteers After A Single Dose Administration

The study was performed to compare the bioavailability of two quetiapine 25 mg tablet formulations: the test formulation was quetiapine fumarate (kitapen®) manufactured by Cobalt Pharmaceuticals, Canada/ Arrow Farmacêutica Ltda* (Erowlabs). Seroquel® (quetiapine) from Astrazeneca Brazil was used as reference formulation. The study was conducted open with randomized two period crossover design and one week wash out period in 64 volunteers of both sexes. Plasma samples were obtained over a 48 hour interval. Quetiapine was analyzed by LC-MS-MS in the presence of quetiapine-D8 as internal standard. Plasma samples were obtained over a 48 hour interval. Quetiapine was analyzed by LC-MS-MS in the presence of quetiapine-D8 as internal standard. The mean ratio of parameters Cmax and AUC 0-t and 90% confidence intervals of correspondents were calculated to determine the bioequivalence. The means AUC 0-t for test and reference formulation were 432.41 ng.h/mL and 412.20 ng.h/mL, for AUC 0-∞ were 440.06 ng.h/mL and 418.90 ng.h/mL and, for Cmax 126.94 ng/mL and 108.71 ng/mL, respectively. Geometric mean of quetiapine (kitapen®)/Seroquel® 25 mg individual percent ratio was 97.68% AUC 0-t, 97.47% for AUC 0-∞ and 90.68% for C max. The 90% confidence intervals were 92.67 - 102.96%, 92.53 - 102.67%, 83.37 - 98.64%, respectively. Since the 90% confidence intervals for C max, AUC 0-t and AUC 0-∞ were within the 80 - 125% interval proposed by Food and Drug Administration, it was concluded that quetiapine (kitapen®) 25 mg tablet was bioequivalent to Seroquel® 25 mg tablet according to both the rate and extent of absorption. © 2011 Junior EA, et al.38178181Barrett, B., Capek, H.M., Huclova, J., Borek-Dohalsky, V., Fejt, P., Validated HPLC-MS/MS method for determination of quetiapine in human plasma (2007) Journal of Pharmaceutical and Biomedical Analysis, 44, pp. 498-505DeVane, C.L., Nemeroff, C.B., Clinical Pharmacokinetics of quetiapine: An Atypical Antipsychotic (2001) Clinical Pharmacokinet, 40, pp. 509-522Kasper, S., Müller-Spahn, F., Review of quetiapine and its clinical applications in schizophrenia (2000) Expert Opin Pharmacother, 1, pp. 783-801Tilden, D., Aristides, M., Meddis, D., Burns, T., An economic assessment of quetiapine and haloperidol in patients with schizophrenia only partially responsive to conventional antipsychotics (2002) Clin Ther., 24, pp. 1648-1667Mario, A., Michael, E., The Role of Quetiapine Extended Release in the Treatment of Bipolar Depression (2010) Adv Ther, 27, pp. 1-11Keck, P., McIntyre, R., Shelton, R., Bipolar depression: Best practices for the outpatient (2007) CNS Spectr., 12, pp. 1-16Judd, L., Akishal, H., Schettler, P., The long-term natural history of the weekly symptomatic status of bipolar I disorder (2002) Arch Gen Psychiatry., 59, pp. 530-537Goldstein, J.M., Atypical antipsychotic drugs: Beyond acute psychosis, new directions (1999) Emerging Drugs, 4, pp. 127-151Abi-Dargham, A., Laruelle, M., Aghajanian, G.K., Charney, D., Krystal, J., The role of serotonin in the pathophysiology and treatment of schizophrenia (1997) J Neuropsychiatry Clin Neurosci, 9, pp. 1-17Kapur, S., Remington, G., Serotonin-dopamine interaction and its relevance to schizophrenia (1996) Am J Psychiatry, 153, pp. 466-476Calabrese, J.R., Keck Jr., P.E., McFadden, W., Minkwitz, M., Ketter, T.A., Weisler, R.H., Cutler, A.J., Mullen, J., A randomized, doubleblind, placebo-controlled trial of quetiapine in the treatment of bipolar I or II depression (2005) Am J Psychiatry, 162, pp. 1351-1360Copolov, D.L., Kowalcyk, B., A multicentre, double-blind, randomized comparison of quetiapine and haloperidol in schizophrenia (2000) Psychol Med, 30, pp. 95-105Figueroa, C., Brecher, M., Hamer-Maansson, J., Pharmacokinetic profiles of extended release quetiapine fumarate compared with quetiapine immediate release (2009) Prog Neuropsychopharmacol Biol Psychiatry, 33, pp. 199-204Goldstein, J.M., Litwin, L.C., Sutton, E.B., Malick, J.B., Seroquel: Electrophysiological profile of a potential atypical antipsychotic (1993) Psychopharmacology, 112, pp. 293-298Kasper, S., Tauscher, J., Küfferle, B., Barnas, C., Pezawas, L., Dopamine and serotonin-receptors in schizophrenia: Results of imaging-studies and implications for pharmacology in schizophrenia (1999) Eur. Arch. Psychiatry Clin. Neurosci., 249, pp. 83-89Peuskens, J., A comparison of quetiapine and chlorpromazine in the treatment of schizophrenia (1997) Acta Psychiatr Scand, 96, pp. 265-273Saller, F., Salama, A.I., Seroquel: Biochemical profile of a potential atypical antipsychotic (1993) Psychopharmacology, 112, pp. 285-292Thase, M.E., McFadden, W., Weisler, R., Efficacy of quetiapine monotherapy in bipolar I and II depression: A double-blind, placebo-controlled study (2006) J Clin Psychopharmacol, 26, pp. 600-609Vieta, E., Mullen, J., Brecher, M., Paulsson, B., Jones, M., Quetiapine monotherapy for mania associated with bipolar disorder: Combined analysis of two international, double-blind, randomised, placebo-controlled studies (2005) Curr Med Res Opin, 21, pp. 923-93

Toward Confined Carbyne with Tailored Properties

Confining carbyne to a space that allows for stability and controlled reactivity is a very appealing approach to have access to materials with tunable optical and electronic properties without rival. Here, we show how controlling the diameter of single-walled carbon nanotubes opens the possibility to grow a confined carbyne with a defined and tunable band gap. The metallicity of the tubes has a minimal influence on the formation of the carbyne, whereas the diameter plays a major role in the growth. It has been found that the properties of confined carbyne can be tailored independently from its length and how these are mostly determined by its interaction with the carbon nanotube. Molecular dynamics simulations have been performed to interpret these findings. Furthermore, the choice of a single-walled carbon nanotube host has been proven crucial even to synthesize an enriched carbyne with the smallest energy gap currently reported and with remarkable homogeneity

A Review of the Properties of Nb3Sn and Their Variation with A15 Composition, Morphology and Strain State

This article gives an overview of the available literature on simplified, well defined (quasi-)homogeneous laboratory samples. After more than 50 years of research on superconductivity in Nb3Sn, a significant amount of results are available, but these are scattered over a multitude of publications. Two reviews exist on the basic properties of A15 materials in general, but no specific review for Nb3Sn is available. This article is intended to provide such an overview. It starts with a basic description of the Niobium-Tin intermetallic. After this it maps the influence of Sn content on the the electron-phonon interaction strength and on the field-temperature phase boundary. The literature on the influence of Cu, Ti and Ta additions will then be briefly summarized. This is followed by a review on the effects of grain size and strain. The article is concluded with a summary of the main results.Comment: Invited Topical Review for Superconductor, Science and Technology. Provisionally scheduled for July 200

On the merit of a Central Limit Theorem-based approximation in statistical physics

The applicability conditions of a recently reported Central Limit Theorem-based approximation method in statistical physics are investigated and rigorously determined. The failure of this method at low and intermediate temperature is proved as well as its inadequacy to disclose quantum criticalities at fixed temperatures. Its high temperature predictions are in addition shown to coincide with those stemming from straightforward appropriate expansions up to (k_B T)^(-2). Our results are clearly illustrated by comparing the exact and approximate temperature dependence of the free energy of some exemplary physical systems.Comment: 12 pages, 1 figur