Galactic center GeV gamma-ray excess from dark matter with gauged lepton numbers

The recently observed excess in gamma-ray signal near the Galactic center suggests that dark matter particles may annihilate into charged fermions that produce gamma-ray to be observed. In this paper, we consider a leptonic dark matter, which annihilates into the standard model leptons, $\mu^+ \mu^-$ and $\tau^+ \tau^-$, by the interaction of the gauged lepton number ${\rm U(1)}_{L_\mu-L_\tau}$ and fits the observed excess. Interestingly, the necessary annihilation cross section for the observed gamma-ray flux provides a good fit to the value for the relic abundance of dark matter. We identify the preferred parameter space of the model after taking the existing experimental constraints from the precision measurements including the muon $(g-2)$, tau decay, neutrino trident production, dark matter direct detection, LHC, and LEP experiments.Comment: 18 pages, 8 figures, references added, matches published versio

Intensification of terrestrial carbon cycle related to El Nino-Southern Oscillation under greenhouse warming

The El Nino/Southern Oscillation (ENSO) drives interannual variation in the global carbon cycle. However, the relationship between ENSO and the carbon cycle can be modulated by climate change due to anthropogenic forcing. We show herein that the sensitivity of the terrestrial carbon flux to ENSO will be enhanced under greenhouse warming by 44% (+/- 15%), indicating a future amplification of carbon-climate interactions. Separating the contributions of the changes in carbon sensitivity reveals that the response of land surface temperature to ENSO and the sensitivity of gross primary production to local temperature are significantly enhanced under greenhouse warming, thereby amplifying the ENSO-carbon-cycle coupling. In a warm climate, depletion of soil moisture increases temperature response in a given ENSO event. These findings suggest that the ENSO-related carbon cycle will be enhanced by hydroclimate changes caused by anthropogenic forcing.113Ysciescopu

Correlation between ambulatory function and clinical factors in hemiplegic patients with intact single lateral corticospinal tract: A pilot study

To define the relationship between the complete destruction of 1 lateral corticospinal tract (CST), as demonstrated by diffusion tensor imaging (DTI) tractography, and ambulatory function 6 months following stroke. Twenty-six adults (17 male, 9 female) with poststroke hemiplegia who were transferred to the physical medicine and rehabilitation department. Participants underwent DTI tractography, which showed that 1 lateral CST had been clearly destroyed. Functional ambulation classification (FAC) scores at admission, discharge, and 6 months after discharge were used to evaluate the patients’ ability to walk. The National Institutes of Health Stroke Scale (NIHSS) and the Korean version of the modified Barthel index (K-MBI) at admission, discharge, and 6 months after discharge were used to evaluate the degree of functional recovery. Of the 26 patients, 18 were nonambulatory (FAC level 1–3), and 8 were able to walk without support (FAC level 4–6). The type of stroke (infarction or hemorrhage), site of the lesion, spasticity of lower extremities, cranioplasty, and the time taken from onset to MRI were not statistically significantly correlated with the ability to walk. However, statistically significant correlations were found in relation to age, K-MBI scores, and initial NIHSS scores. Despite the complete damage to the lesion site and the preservation of 1 unilateral CST, as shown by DTI, good outcomes can be predicted on the basis of younger age, low NIHSS scores, and high MBI scores at onset

Role of local air‐sea interaction in fire activity over Equatorial Asia

Fire activity in Equatorial Asia shows large interannual variability. Teleconnections by El Nino-Southern Oscillation and Indian Ocean Dipole are linked to drought and fire events; however, we found here that significant role of local Sea Surface Temperature (SST) over the Banda Sea in interannual variability of Equatorial Asian burned area in October even after removing the linear effects of teleconnections. October is the transient period from dry to wet season and strengthened seasonal circulation in October leads to a negative SST anomaly through Wind-Evaporation-SST mechanism. This anomalous local air-sea interaction sustains the dry season into October and stronger fire activity. Moreover, we found that the sensitivity of precipitation to SST is higher in October than in other months, hence fires in Equatorial Asia can be sensitively driven by local SST changes. Identification of this sensitivity will underpin better predictions of fire activity and air quality in Equatorial Asia.11Nsciescopu

Intensified Arctic warming under greenhouse warming by vegetation–atmosphere–sea ice interaction

Observations and modeling studies indicate that enhanced vegetation activities over high latitudes under an elevated CO2 concentration accelerate surface warming by reducing the surface albedo. In this study, we suggest that vegetation-atmosphere-sea ice interactions over high latitudes can induce an additional amplification of Arctic warming. Our hypothesis is tested by a series of coupled vegetation-climate model simulations under 2xCO(2) environments. The increased vegetation activities over high latitudes under a 2xCO(2) condition induce additional surface warming and turbulent heat fluxes to the atmosphere, which are transported to the Arctic through the atmosphere. This causes additional sea-ice melting and upper-ocean warming during the warm season. As a consequence, the Arctic and high-latitude warming is greatly amplified in the following winter and spring, which further promotes vegetation activities the following year. We conclude that the vegetation-atmosphere-sea ice interaction gives rise to additional positive feedback of the Arctic amplification.open1188sciescopu

Extensive fires in southeastern Siberian permafrost linked to preceding Arctic Oscillation

Carbon release through boreal fires could considerably accelerate Arctic warming; however, boreal fire occurrence mechanisms and dynamics remain largely unknown. Here, we analyze fire activity and relevant large-scale atmospheric conditions over southeastern Siberia, which has the largest burned area fraction in the circumboreal and high-level carbon emissions due to high-density peatlands. It is found that the annual burned area increased when a positive Arctic Oscillation (AO) takes place in early months of the year, despite peak fire season occurring 1 to 2 months later. A local high-pressure system linked to the AO drives a high- temperature anomaly in late winter, causing premature snowmelt. This causes earlier ground surface exposure and drier ground in spring due to enhanced evaporation, promoting fire spreading. Recently, southeastern Siberia has experienced warming and snow retreat; therefore, southeastern Siberia requires appropriate fire management strategies to prevent massive carbon release and accelerated global warming.11Ysciescopu

Data Envelopment Analysis for establishing the financial benchmark of Korean hotels

In the wake of catastrophic natural disasters and rising threats of terrorism, the hotel industry has seen a decline in revenue and an increase in competition. To avoid a downward spiral, the hotel industry needs to develop more competitive business strategies in order to make its operations lean and robust. These strategies may include: customer relationship management, yield management, niche marketing and continuous improvement of financial health. The success of these strategies hinges on the ability of hotel managers to assess the financial efficiency of their hotel in comparison to competition. In an effort to help hotel management enhance its financial efficiency in an increasingly competitive hotel industry, this paper proposes a Data Envelopment Analysis (DEA), which develops a meaningful set of benchmarks that will dictate best practices and form a successful hotel business model. Using the examples of 39 international and regional hotels in Korea, this paper illustrates the usefulness of DEA for the continuous improvement of hotel business practice