ALBERT

Description: The plasma sheet pressure and its spatial structure during the substorm growth phase are crucial to understanding the development and initiation of substorms. In this paper, we first statistically analyzed the growth phase pressures using Geotail and THEMIS data, and identified that solar wind dynamic pressure (P SW ), energy loading, and sunspot number as the three primary factors controlling the growth phase pressure change. We then constructed a 2D equatorial empirical pressure model and an error model within r ≤ 20 R E using the Support Vector Regression Machine (SVRM) with the three factors as input. The model predicts the plasma sheet pressure accurately with median errors of 5%, and predicted pressure gradients agree reasonably well with observed gradients obtained from two-probe measurements. The model shows that pressure increases linearly as P SW increases, and the P SW effect is stronger under lower energy loading. However, the pressure responses to energy loading and sunspot number are nonlinear. The pressure increases first with increasing loading or sunspot number, then remains relatively constant after reaching a peak value at ~8000 kV∙min loading or sunspot number of ~80. The loading effect is stronger when P SW is lower and the pressure variations stronger near midnight than away from midnight. The sunspot number effect is clearer at smaller r. The pressure model can also be applied to understand the pressure changes observed during a substorm event by providing evaluations of the effects of energy loading and P SW , as well as the temporal and spatial effects along the spacecraft trajectory.

Description: Stratosphere-troposphere exchange (STE) of ozone (O 3 ) is key in the budget of tropospheric O 3 , in turn affecting climate forcing and global air quality. We compare three commonly used diagnostics meant to quantify cross-tropopause O 3 fluxes with a Chemistry-Transport Model driven by two distinct European Centre forecast fields. Our reference case calculates accurate, geographically resolved net transport across an iso-surface in artificial tracer e90 representing the tropopause. Hemispheric fluxes derived from the ozone mass budget of the lowermost stratosphere yield similar results. Use of the Brewer-Dobson residual vertical velocity as a scaled proxy for ozone flux, however, fails to capture the interannual variability. Thus, the common notion that the strength of stratospheric overturning circulation is a good measure for global STE does not apply to O 3 . Climatic variability in the modeled O 3 flux needs to be diagnosed directly rather than indirectly through the overturning circulation.

Description: The number of Chinese tourists visiting Taiwan has been closely related to the political relationship across the Taiwan Strait. The occurrence of political events and disasters or accidents have had, and will continue to have, a huge impact on the Taiwan tourism market. To date, there has been relatively little empirical research conducted on this issue. Tourists are characterized as being involved in one of three types of tourism: group tourism (group-type), individual tourism (individual-type), and medical cosmetology (medical-type). We use the fundamental equation in tourism finance to examine the correlation that exists between the rate of change in the number of tourists and the rate of return on tourism. Second, we use the event study method to observe whether the numbers of tourists have changed abnormally before and after the occurrence of major events on both sides of the Strait. Three different types of conditional variance models, namely, the Generalized Autoregressive Conditional Heteroscedasticity, GARCH (1,1), Glosten, Jagannathan and Runkle, GJR (1,1) and Exponential GARCH, EGARCH (1,1), are used to estimate the abnormal rate of change in the number of tourists. The empirical results concerning the major events affecting the changes in the numbers of tourists from China to Taiwan are economically significant, and confirm the types of tourists that are most likely to be affected by such major events.

Description: Analytical Chemistry DOI: 10.1021/acs.analchem.7b01096

Description: Although the main purpose of the torrefaction of biomass is to produce high quality solid bio-fuel, the by-products, including liquid and gas products, are worth investigating to know their effects on the environment and the reusable possibility. Consequently, after torrefying waste bamboo chopsticks (WBCs) for producing solid bio-fuel, the liquid and gas products were examined in this study. The torrefaction target was set to produce torrefied waste bamboo chopsticks (WBCT) retaining about 70 wt %. A proper torrefaction temperature (Tr) and torrefaction time (tr) were found at 563 K and 40 min, respectively, for carrying out the torrefaction in a tubular furnace with carrier nitrogen. These conditions gave a solid yield (YS) of 69 wt % of WBCT relative to the original WBC, and 31 wt % of by-products were produced. The liquid products were composed of water as high as 62 wt %, along with some organic acids. Some medicine components were also found in the liquid products, representing potential medicine applications. During torrefaction, CO, NOx, SO2, and CO2 emissions were largely discharged from 10 to 20 min of torrefaction time. O2, CO2, and H2O are the major compounds in the total gas products collected. Some combustible gases of C1 to C6 hydrocarbons were also produced. Moreover, the gas volume balances were computed and evaluated. The information obtained in this study is useful for the proper design, operation, pollution control, and utilization of the products.

Description: Amygdala-hippocampal dynamics during salient information processing Nature Communications, Published online: 8 February 2017; doi:10.1038/ncomms14413 Amygdala and hippocampus are involved in processing motivationally salient stimuli but the precise circuit dynamics of the interaction is not understood. Here the authors show that in response to fearful faces in humans, theta/alpha oscillations in the amygdala modulate hippocampal activity dynamics.

Description: [1]  Some key photochemical uncertainties that cannot be readily eliminated by current observations translate into a range of stratospheric O 3 abundances in the tens of percent. The uncertainty in O 3 production due to that in the cross sections for O 2 in the Hertzberg continuum is studied here with the NCAR Community Atmosphere Model, which allows for interactive climate and ozone chemistry. A min-max range in the O 2 cross sections of 30%, consistent with current uncertainties, changes O 3 abundances in the lower tropical stratosphere by up to 30%, with a relatively smaller and opposite change above 30 hPa. Here we have systematically examined the changes in the time-mean state, the seasonal cycle, and the interannual variability of the temperature and circulation associated with the ±30% change in O 2 cross sections. This study points to the important role of O 3 in the lower tropical stratosphere in determining the physical characteristics of the tropical tropopause layer. Reducing O 2 cross sections by 30% increases ozone abundances which warms the lower stratosphere (60S -60 N; 2 K maximum at equator) and lowers the tropopause height by 100-200 m (30S -30 N). The large-scale warming leads to enhanced stratification near the tropopause which reduces upward wave propagation everywhere except for high latitudes. The lowermost tropical stratosphere is better ventilated during austral winter. The annual cycle of ozone is amplified. The interannual variability of the winter stratospheric polar vortices also increases, but the mechanism involves wave-mean flow interaction and the exact role of ozone in it needs further investigation.

Description: INTRODUCTION: Vaso-occlusion causes tissue ischemia and severe pain in patients with sickle cell disease (SCD). The liver is frequently involved in human SCD complications and elevated serum levels of hepatic transaminases often accompany vasoocclusive pain. It is unknown whether in sickle cell disease, the liver sustains oxidative damage after hypoxia-reoxygenation and if so, how long does it take to recover. Both mitochondrial and cytosolic aconitases are potential targets of oxidants in cells due to the oxidant-mediated loss of iron from the [4Fe-4S] cluster. Oxidant damage can occur from the reactive oxygen species generated by dysfunctional mitochondria dysfunction following ischemia-reperfusion and also from peroxidases later released during the inflammatory reaction to tissue injury. A mouse model of SCD can be used to investigate the cellular mechanisms and temporal sequence of vaso-occlusive tissue damage. OBJECTIVES: After experimental vaso-occlusion by exposing sickle cell mice to hypoxia-reoxygenation, we will determine whether hepatocellular injury shows temporal correlation with a marker of oxidative damage (diminished aconitase activity) and a marker of inflammation (increased myeloperoxidase concentration). No changes are predicted to occur in littermate control mice whose erythrocytes do not sickle with hypoxic challenge. METHODS: Mice expressing exclusively human sickle cell hemoglobin (“Berkeley sickle mice”) and non-sickling littermate controls (“hemizygotes”) were exposed to 10% oxygen for 2 hours, and then restored to normoxia. At 6, 18, 48, or 72 hrs after hypoxia, animals were euthanized to harvest blood and liver tissue. Normoxic control mice of both types had blood and liver harvested without hypoxic exposure. Additional sickle cell mice received intraperitoneal injection of nitrite (2.4 millimole/g body weight) or saline control at the end of 2 hours of hypoxia, then had blood and liver harvested 18 hours after they were restored to normoxia. Serum alanine aminotransferase (ALT) level was assayed as a quantitative measure of hepatocellular injury. Aconitase and myeloperoxidase (MPO) results were compared by t-test. RESULTS: Serum ALT level rose 3-fold in sickle mice by 18 hr after hypoxia, and then declined by 48 and 72 hrs after hypoxia. Hemizygotes showed no change in ALT after hypoxia. Liver homogenate aconitase activity was significantly lower in sickle mice than in hemizygotes at the first time point measured, 6 hrs after hypoxia (p=0.003, n=4 per group), suggesting that oxidative damage to the enzyme had occurred early after hypoxia. MPO concentration in livers harvested 48 hr after hypoxia-reoxygenation was 3-fold elevated in sickle mice vs. hemizygotes (p=0.006, n=4 per group), but not at baseline or 72 hr after hypoxia-reoxygenation. Nitrite injection was associated with complete abrogation of rise in ALT in sickle mice challenged with hypoxia-reoxygenation, but was not associated with any differences in aconitase activity or MPO concentration. CONCLUSION: Serum ALT, liver aconitase activity, and liver MPO concentration had different temporal patterns of changes in sickle mice after hypoxia-reoxygenation challenge as an experimental model of vaso-occlusive tissue injury. Oxidative stress appears to be present within hours after hypoxia, followed by tissue injury (serum ALT rise), which is then followed by inflammation may take 48 hr after experimental vasoocclusion. Although the nitrite is not sufficient as antioxidant to protect against reactive oxygen species and inflammatory leukocytes, nitrite may be protective against tissue injury at the mitochondrial level. This experimental model system may be well-suited for pre-clinical testing of therapy for sickle cell vaso-occlusion.