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Straddles on individual stocks generally earn negative and significant returns. However, average at-the-money straddles from 3 days before an earnings announcement to the announcement date yield a highly significant 3.34% return. The positive returns on straddles indicate that investors underestimate the magnitude of uncertainty around earnings announcements. We find that positive straddle returns are more pronounced for smaller firms and firms with higher volatility, higher kurtosis, more volatile past earnings surprises, and less trading volume/higher transaction costs. This suggests that when firm signals are noisy, and/or when it is costlier to trade, investors underestimate the uncertainty associated with earnings announcements.
The crack initiation and early growth behaviors of a TC4 titanium alloy under high cycle fatigue and very high cycle fatigue were experimentally investigated. The results show that it exhibits the duplex S–N curve characteristics associated with surface and interior failures at a stress ratio of 0.1, while it represents the similar S–N curve characteristics only related to surface failure at a stress ratio of −1. The interior failure is accompanied with the occurrence of facets, granular bright facets (GBFs), and fisheye. Slip-like patterns are observable on the facets easily formed under positive stress ratio. The interior failure process is characterized as (i) occurrence of slip lines on partial α grains under cyclic loading, (ii) initiation and growth of microcracks within some α grains, (iii) coalescence of microcracks and formation of GBF, (iv) stable long crack growth within fisheye, (v) unstable crack growth outside fisheye, and (vi) final momentary fracture.
With increasing output of petroleum coke, the value-added exploitation of petroleum coke has become a tough problem. Preparing porous carbons is a traditional way to the value-added exploitation of petroleum coke. Here, we used a facile and efficient hard-templating strategy to synthesize mesoporous carbon with high surface area from petroleum coke. N2 adsorption analyses show that the BET specific area and pore volume of the carbons can reach up to 864 m2/g and 1.37 cm3/g, respectively. To utilize the abundant mesopores of the carbons, anthraquinone-modified mesoporous carbon was tested as an electrode material for supercapacitor applications. Electrochemical measurements demonstrated that the specific capacitance reached up to 366 F/g at the current density of 1 A/g, indicating a promising prospect of using this carbon in electrochemical energy-storage field. More importantly, the strategy used in this work can be easily modified to prepare other nano-carbon materials from petroleum coke.
Gamma-ray observations for Supernova remnant (SNR)-molecular cloud (MC) association systems play an important role in the research on the acceleration and propagation of cosmic-ray protons. Through the analysis of 5.6 years of Fermi-Large Area Telescope observation data, here we report on the detection of a gamma-ray emission source near the SNR Kesteven 41 with a significance of 24σ in 0.2–300 GeV. The best-fit location of the gamma-ray source is consistent with the MC with which the SNR interacts. Several hypotheses including both leptonic and hadronic scenarios are considered to investigate the origin of these gamma-rays. The gamma-ray emission can be naturally explained by the decay of neutral pions produced via the collision between high energy protons accelerated by the shock of Kesteven 41 and the adjacent MC. The electron energy budget would be too high for the SNR if the gamma-rays were produced via inverse Compton (IC) scattering off the Cosmic Microwave Background (CMB) photons.
Outside surface fluctuations of inertial confinement fusion (ICF) capsule greatly affect the implosion performance. An atomic force microscope (AFM)-based profilometer is developed to precisely characterize the capsule surface with nanometer resolution. With the standard nine surface profiles and the complete coverage data, 1D and 2D power spectra are obtained to quantitatively qualify the capsule. Capsule center fast aligning, orbit traces automatic recording, 3D capsule orientation have been studied to improve the accuracy and efficiency of the profilometer.
Foxtail millet (Setaria italica (L.) P. Beauv.) is a naturally stress-tolerant plant, a major reserve crop and a model for panicoid grasses. The recent completion of the S. italica genome facilitates identification and characterization of WRKY transcription factor family proteins that are important regulators of major plant processes, including growth, development and stress response. The present study identified 103 WRKY transcription factor-encoding genes in the S. italica genome. The genes were named SiWRKY1–SiWRKY103 according to their order on the chromosomes. A comprehensive expression analysis of SiWRKY genes among four different tissues was performed using publicly available RNA sequencing data. Eighty-four SiWRKY genes were more highly expressed in root tissue than in other tissues and nine genes were only expressed in roots. Additionally, real-time quantitative polymerase chain reaction was performed to comprehensively analyse the expression of all SiWRKY genes in response to dehydration. Results indicated that most SiWRKY genes (over 0.8) were up-regulated by drought stress. In conclusion, genome-wide identification and expression profiling of SiWRKY genes provided a set of candidates for cloning and functional analyses in plants’ response to drought stress.
The metamorphic responses of mussel (Mytilus coruscus) larvae to pharmacological agents affecting G proteins and the adenylate cyclase/cyclic AMP (AC/cAMP) pathway were examined in the laboratory. The G protein activators guanosine 5′-[β,γ-imido]triphosphate trisodium salt hydrate and guanosine 5′-[γ-thio]triphosphate tetralithium salt only induced larval metamorphosis in continuous exposure assays, and the G protein inhibitor guanosine 5′-[β-thio]diphosphate trilithium salt did not exhibit inducing activity. The non-specific phosphodiesterase inhibitor theophylline and the cAMP-specific phosphodiesterase IV inhibitor 4-(3-Butoxy-4-methoxybenzyl)imidazolidin-2-one exhibited inducing activity, while the non-specific phosphodiesterase inhibitor 3-Isobutyl-1-methylxanthine only showed inducing activity at 10−4 M in continuous exposure assays. The cyclic nucleotide analogue N6,2′-O-Dibutyryladenosine 3′,5′-cyclic monophosphate sodium salt did not exhibit significant inducing activity. Both the adenylate cyclase activator forskolin and the adenylate cyclase inhibitor nitroimidazole exhibited inducing activity at 10−4 to 10−3 M concentrations in continuous exposure assays. Among these tested agents, the adenylate cyclase inhibitor (±)-miconazole nitrate salt showed the most promising inducing effect. The present results indicate that G protein-coupled receptors and signal transduction by AC/cAMP pathway could mediate metamorphosis of larvae in this species.
Susan Keates and Yaroslav Kuzmin have contributed valuable comments on our assessment of the chronology and technological characteristics of Shuidonggou localities 1 and 2. These comments have demonstrated some discordance in our publications that should be corrected here. Their rationale for abandoning the conclusions altogether is, however, weak at best. Most importantly, there is no reason to return to the chronology for the Initial Upper Palaeolithic (hereafter termed IUP) assemblages at the Shuidonggou site complex (SDG) proposed by Madsen et al. (2001). Keates and Kuzmin's critique focuses on two separate issues: the first is our characterisation of the assemblages from the lower part of SDG 2, and the second is our handling of the dates. We will address these in order.
The erosion–corrosion properties and interface microstructure of a Fe–B alloy that contains 3.5 wt% B in flowing liquid zinc have been investigated by electron backscattered diffraction, x-ray diffraction, and scanning electron microscopy to clarify the flowing effect of liquid zinc on erosion performance using a rotating-disk technique. The Fe–B alloy erodes at a low and steady rate in flowing liquid zinc. Flowing liquid zinc can accelerate the iron and zinc mass transfer to form Fe–Zn compounds and promote the removal of loose FeZn13. Much residual corrosion-resistant Fe2B and some erosion products coexist at the erosion interface because of the chemical and micromechanical effects that are created by flowing liquid zinc. The failure of the Fe2B corrosion-resistant skeleton in flowing liquid zinc occurs because of the loss of supporting matrix and also the formation and spread of microcracks during erosion.
A review of recently published temporal data from Shuidonggou Locality 1 indicates that a 40–43 cal ka date for the inception of Initial Upper Paleolithic (IUP) blade-oriented technologies in East Asia is warranted. Comparison of the dates from Shuidonggou to other Asian IUP dates in Korea, Siberia, and Mongolia supports this assertion, indicating that the initial appearance of the IUP in East Asia generally corresponds in time to the fluorescence of the IUP in eastern Europe and western Asia. This conclusion preliminarily suggests that either a version of the IUP originated independently in East Asia just prior to 40 cal ka, or more likely, that an early, initial diffusion of the IUP into East Asia occurred ∼41 cal ka, a hypothesis consistent with current estimates for the evolution or arrival of modern humans in the region.
Red skin disease seriously limits the production and quality of Panax ginseng (ginseng) in the Changbai Mountains of Northeast China, which is the main origin of ginseng. To cultivate ginseng, the albic and humus horizons of albic luvisols are artificially mixed to produce ginseng bed soils. To clarify the relationship between red skin disease and soil characteristics, red skin disease indices were calculated from six plots located on a ginseng farm. Ginseng roots were analysed for aluminium (Al) content. Soils from the ginseng beds were sampled at three depths for the evaluation of physico-chemical parameters. Al fractionation from the soil solid fraction was analysed using atomic absorption spectrophotometry. Ginseng plants exhibiting larger red skin areas accumulated higher concentrations of Al in the epidermis and in the fibrous roots. Ginseng bed soils in the six plots were acidic with pHH2O values ranging from 4.0 to 5.0. Plots exhibiting higher red skin disease indices also had higher bulk densities, moisture contents and nitrate concentrations. They also contained higher concentrations of exchangeable Al, NaOH-extracted Al and ammonium oxalate-oxalic-extracted Al in the bed soils. The Al saturation and molar ratio of base cations to Al were above 20% and below 10, respectively, in the two plots with the highest disease indices. Compact soils with higher moisture, nitrate concentrations and active Al species may increase the incidence of ginseng red skin disease.
The Shuidonggou site cluster in northern China contains 12 different early prehistoric sequences with great potential to cast light on the transition to Upper Palaeolithic behaviour in East Asia. Here researchers present the latest results from Locality 2, reporting seven occupation levels with hearths, animal bone and diverse industries. Although previously compared with European Upper Palaeolithic sequences, the new work proposes a different trajectory of development. Distinctive macroblade technology arrived in the area, possibly from Mongolia or Siberia, about 41000–34000 years ago. This industry subsequently disappeared, to be replaced by flake technologies.
It is well known that extracellular signal-regulated kinase 8 (ERK8) plays pivotal roles in various mitotic events. But its physiological roles in oocyte meiotic maturation remain unclear. In this study, we found that although no specific ERK8 signal was detected in oocyte at the germinal vesicle stage, ERK8 began to migrate to the periphery of chromosomes shortly after germinal vesicle breakdown. At prometaphase I, metaphase I (MI), anaphase I, telophase I, and metaphase II (MII) stages, ERK8 was stably detected at the spindles. By taxol treatment, we clarified that the ERK8 signal was stained on the spindle fibers as well as microtubule asters in MI and MII oocytes. In fertilized eggs, the ERK8 signal was not observed in the two pronuclei stages. At prometaphase, metaphase, and anaphase of the first mitosis, ERK8 was detected on the mitotic spindle. ERK8 knock down by antibody microinjection and specific siRNA caused abnormal spindles, failed chromosome congression, and decreased first polar body extrusion. Taken together, our results suggest that ERK8 plays an important role in spindle organization during mouse oocyte meiotic maturation and early embryo cleavage.
We investigate the interfacial electronic structures of the heterojunction Fe/pentacene/Fe on Cu(100) substrate, using synchrotron-based photoemission spectroscopy. No chemical reaction is observed at either Fe/pentacene or pentacene/Fe interface. The hole injection barrier was estimated to be about 0.95 eV between pentacene and under the Fe thin film. C K-edge NEXAFS revealed that the long axis of pentacene molecule was almost perpendicular to the surface plane. With increasing Fe thickness deposited on pentacene film, the pentacene's HOMO shifts to higher binding energy whereas the C 1s binding energy showed an interesting unusual behaviour due to the initial band bending gradually suppressed by the increasing core-hole screening effect.
To evaluate the effect of antioxidant defence in coelomic fluid of sea cucumber, Apostichopus japonicus in aestivation was studied in the field from July to November 2006 in Qingdao. During the sampling period, activities of superoxide dismutase and catalase increased significantly in August and November. Activities of glutathione reductase and glutathione decreased significantly in August and increased significantly in November and activities of Se-glutathione peroxidase increased significantly in August. There were no significant differences in total glutathione peroxidase. In relation to the water temperature in the field, it is known that the oxygen consumption rate dropped and antioxidant defence was enhanced in August. The structure and function of respiratory trees of A. japonicus were completely vivified as normal in November, and it is suggested that antioxidant defence was enhanced because of the sharp change of oxygen consumption. Data indicate that both enzymatic and metabolite antioxidant defences in sea cucumber are adaptable systems that are modulated during pre-aestivating stage and arousing stage.
Novel poly(3,6-hexyl-2,7-N-octylcarbazole) derivatives and poly(diindolocarbazole)s were synthesized. Optical, electrochemical, electrical and thermoelectric properties were investigated. Band structure calculations were used to predict which polymers were promising as thermoelectric materials. The best combination of Seebeck coefficient and conductivity (power factor) was 9,4 x10-8 Wm-1K-2 with a copolymer of carbazole and thiophene. This corresponds to a ZT at room temperature of 0.0003. Optimization of the polymer structure and doping level should lead to an increased ZT.
This paper reports U-series dates on speleothem samples from Locality 15 at Zhoukoudian, one of the richest Paleolithic sites in northern China. The age of the lower part of Layer 2 is securely bracketed between 155,000 and 284,000 yr. The underlying Layer 3 dates back at least 284,000 yr. Layer 4, further below, should be older still, possibly by a cycle on the SPECMAP time scale before 284,000 yr ago. These ages, much greater than the previous estimates of 110,000"140,000 yr from U-series and electron spin resonance dating of fossil teeth, suggest that Locality 15 was broadly contemporaneous with Locality 4 (New Cave) and with the uppermost strata of Locality 1 (Peking Man site). The physical evolution and cultural development evidenced by the timing of the Zhoukoudian localities are in line with the opinion of Chinese anthropologists for a regional transition from Homo erectus to archaic Homo sapiens.
The Chinese Palaeolithic has traditionally been divided into three distinct cultural periods: Lower, Middle, and Upper. Analysis of four stone tool criteria (raw material procurement, core reduction, retouch, and typology) to determine if a distinct Middle Palaeolithic stage existed in China suggests that very little change occurred in lithic technology between the Lower and Middle Palaeolithic. Accordingly, a two-stage progression is proposed: Early and Late Palaeolithic. The transition between these two cultural periods occurred with the development of more refined stone tool making techniques (e.g. introduction of blade and microblade technology) and the presence of other archaeological indicators of more modern human behaviour (e.g. presence of art and/or symbolism) (c. 30,000 years ago).
Shuidonggou is unique within the Chinese Palaeolithic sequence and its assemblage is reminiscent of Upper Palaeolithic core-and-blade technologies in Mongolia and southern Siberia. Limited chronological controls have prevented evaluation of this technology in both the Chinese and greater Eurasian Palaeolithic. Dating of recently discovered hearths at Locality 2 places Shuidonggou firmly at 29,000–24,000 BP, and suggests the spread of the Eurasian large blade technology was primarily from north to south. The concurrent production of small microblade-like bipolar bladelets at the site may also presage the development of a microlithic industry.
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