Development of a Regional Regression Model for Estimating Annual Runoff in the Hailar River Basin of China

The Hailar River, a first-grade tributary of the Erguna River that borders China and Russia, is the main water source for the local industry and agriculture. However, because there are only 11 flow gauging stations and those stations cannot monitor all runoff paths, it is hard to directly use the existing flow data to estimate the annual runoffs from all subbasins of interest although such estimation is needed for utilization and protection of the water resources in the Hailar River. Thus, this study implemented an indirect approach (i.e., regional regression model) by correlating annual runoff with annual rainfall and water surface evaporation as well as hydrologic characteristics of the 11 subbasins monitored by the gauging stations. The study used 51 years (from 1956 to 2006) data. The results indicated a significant correlation (R2 > 0.87) between annual runoff and the selected subbasin characteristics and showed the model to be robust because the predicted runoffs for the validation period are compatible with the corresponding observed values. In addition, this model was used to estimate the annual runoffs for the subbasins that are not monitored by the 11 flow gauging stations, which adds new information to existing literature.

Influences of landform as a confounding variable on SOM-NDVI association in semiarid Ordos Plateau

Soil organic matter （SOM） plays an important role in maintaining vegetation cover and thus mitigating land erosion of fragile terrestrial ecosystems such as in the Northern Ordos Plateau of China （NOPC）. However, little information is available on whether and how SOM varies spatially as an intrinsic characteristic of landform in NOPC. The objective of this study was to examine the spatial associations of SOM with landform and vegetation cover. The study was conducted in a 23,000-km2 area within NOPC because this area has landforms of mobile dunes （MD）, flat dunes （FD）, grassy sandy land （GSL）, flat sandy bedrocks （FSB）, and swamps and salt lakes （SW）, which are typical landforms in semiarid ecosystems. SOM was determined using a standard laboratory analysis method for 5 cm topsoil samples collected at 72 locations across the study area. In addition, the 250 m Multitem- poral Moderate Resolution Imaging Spectroradiometer （MODIS） imageries taken in the period from August 2006 to August 2010 were used to extract Normalized Difference Vegetation Index （NDVI） which in turn was used as the surrogate of vegetation cover. Classic and geostatistical methods were used to compare SOM concentration across different landforms. The results indicated that an area with a greater value for NDVI （i.e. better vegetation cover） tended to have a higher SOM concentration regardless of the landform types. However, the association between SOM and NDVI varied from one landform to another. The SW and GSL had a highest SOM concentration, while MD had a lowest concentration. For the study area as a whole and the FD, GSL, and MD, SOM was found to be the sole function of NDVI, whereas, for the FSB, SOM was influenced by several intrinsic variables, namely ground surface altitude, slope, and aspect, as well as NDVI. SOM for the SW landform was found to be a function of NDVI. Furthermore, SOM and NDVI exhibited a consistent spatial pattern of increasing from north to south and from west to east. The highest SOM concentration of 3.5% occurred along an east-westward belt, which is adjacent to water pathways, in the mid part of the study area.

A stopping layer concept to improve the spatial resolution of gas-electron-multiplier neutron detector

In recent years,gas electron multiplier(GEM)neutron detectors have been developing towards high spatial resolution and high dynamic counting range.We propose a novel concept of an Al stopping layer to enable the detector to achieve sub-millimeter(sub-mm)spatial resolution.The neutron conversion layer is coated with the Al stopping layer to limit the emission angle of ions into the drift region.The short track projection of ions is obtained on the signal readout board,and the detector would get good spatial resolution.The spatial resolutions of the GEM neutron detector with the Al stopping layer are simulated and optimized based on Geant4 Garfield Interface.The spatial resolution of the detector is 0.76 mm and the thermal neutron detection efficiency is about 0.01%when the Al stopping layer is 3.0μm thick,the drift region is 2 mm thick,the strip pitch is 600μm,and the digital readout is employed.Thus,the GEM neutron detector with a simple detector structure and a fast readout mode is developed to obtain a high spatial resolution and high dynamic counting range.It could be used for the direct measurement of a high-flux neutron beam,such as Bragg transmission imaging,very small-angle scattering neutron detection and neutron beam diagnostic.

Clinical features of multiple myeloma patients with isolated extramedullary relapse

This study sought to analyze the clinical features and prognosis of multiple myeloma with isolated extramedullary relapse and with the absence of systemic progression.The clinical features and outcome were retrospectively analyzed in six multiple myeloma patients.These patients had secretory multiple myeloma at diagnosis.When relapsed,the dissociation between medullary and extramedullary response was detected.The serum or urine monoclonal component was extremely low or absent.The plasma cells in bone marrow were 〈5%.All patients received new targeted therapies（thalidomide or bortezomib） before extramedullary relapse.It is difficult to achieve second remission for them.Even in those showing response,the duration of response was extremely short.The median of overall survival from diagnosis and from extramedullary relapse was 19 months and 6 months,respectively.The overall survival was significantly shorter compared to the patients without extramedullary involvement（84 months,P= 0.001）.These patients exhibited a special and rare relapse pattern.Patients with this relapse pattern were resistant to current therapies,including novel targeted agents and associated with poor prognosis.

Clinical Characteristics and Outcomes of Severe or Critical COVID-19 Patients Presenting No Respiratory Symptoms or Fever at Onset

It is difficult to identify suspected cases of atypical patients with coronavirus disease 2019(COVID-19),and data on severe or critical patients are scanty.This retrospective study presents the clinical,laboratory,and radiological profiles,treatments,and outcomes of atypical COVID-19 patients without respiratory symptoms or fever at onset.The study examined ten atypical patients out of 909 severe or critical patients diagnosed with COVID-19 in Wuhan Union Hospital West Campus between 25 January 2020 and 10 February 2020.Data were obtained from the electronic medical records of severe or critical patients without respiratory symptoms or fever at onset.Outcomes were followed up to discharge or death.Among 943 COVID-19 patients,909(96.4%)were severe or critical type.Of the severe or critical patients,ten(1.1%)presented without respiratory symptoms or fever at admission.The median age of the ten participants was 63 years(interquartile range(IQR):57–72),and seven participants were men.The median time from symptom onset to admission was 14 d(IQR:7–20).Eight of the ten patients had chronic diseases.The patients had fatigue(n=5),headache or dizziness(n=4),diarrhea(n=5),anorexia(n=3),nausea or vomiting(n=3),and eye discomfort(n=1).Four patients were found to have lymphopenia.Imaging examination revealed that nine patients had bilateral pneumonia and one had unilateral pneumonia.Eventually,two patients died and eight were discharged.In the discharged patients,the median time from admission to discharge lasted 24 d(IQR:13–43).In summary,some severe or critical COVID-19 patients were found to have no respiratory symptoms or fever at onset.All such atypical cases should be identified and quarantined as early as possible,since they tend to have a prolonged hospital stay or fatal outcomes.Chest computed tomography(CT)scan and nucleic acid detection should be performed immediately on close contacts of COVID-19 patients to screen out those with atypical infections,even if the contacts present without respiratory symptoms or fever at onset.

Measurement of fast neutrons with ^(238)U-coated fission chamber

Purpose Afission chamber with two layers of 238Ufissile materials has been developed for the measurements of fast neutrons.Methods The developed fission chamber has been tested by 60Co gamma source and 252Cf neutron source.Results The results have indicated that it is very easy to cut off the gamma rays from the neutrons by using a discriminator,when the fission chamber works in the pulse mode.The detector works well,even if the static air is used as the filling gas.Conclusion To discuss the application of the detector,Monte Carlo simulations have been performed by considering four 238U-coated fission chambers located outside the spallation target for the fast neutron measurement from spallation reaction.The simulation results have indicated that the detector can be used to measure the fast neutron flux and neutron flux ratio of four fission chambers.Furthermore,a 238U-coated fission chamber can be used within a reactor for longer time,in comparison with a 235U-coated fission chamber.