Incidental PET/CT Findings of Suspected COVID-19 in a Region of High Prevalence.

We describe a case of suspected COVID-19 pneumonia in a 61-year-old male with known primary central nervous system diffuse large B-cell lymphoma (DLBCL) who underwent restaging PET/CT during the initial peak of infection of COVID-19 pneumonia within the New York region. At the time of his routine PET-CT to assess for disease progression, typical CT imaging features of COVID-19 pneumonia were identified. Upon further investigation, the patient was asymptomatic, and his infection status remained unknown. He was subsequently lost to follow-up with his COVID-19 status pending

Conditions chimiques contrôlant l'atténuation naturelle des BTEX et solvants chlorés : un état des connaissances

L'atténuation naturelle des BTEX (Benzène, Toluène, Ethyl-benzène, Xylène) et des solvants chlorés est de plus en plus étudiée en raison des potentialités offertes par cette technique de gestion. Cet article, après avoir présenté les aspects abiotiques de l'atténuation détaille les conditions chimiques nécessaires à la réalisation des réactions de biodégradation des polluants organiques. Les aspects thermodynamiques sont abordés afin de décliner les réactions possibles et celles qui ne le sont pas selon les environnements chimiques. La dégradation des BTEX est focalisée sur le benzène, produit le plus toxique et le moins dégradable sur la plupart des sites. Les détails de la dégradation du benzène sur le terrain sont analysés dans la littérature et leur comparaison permet de décrire les mécanismes responsables de celle-ci. Dans le cas des solvants chlorés, l'attention est portée sur le TCE (Trichloréthylène), produit le plus couramment rencontré sur les sites pollués. Une mise en parallèle des évolutions de teneurs observées et des conditions chimiques locales permet de mettre en évidence les conditions nécessaires à la dégradation du TCE, et de ses congénères, ainsi que les cinétiques de dégradation dans différentes conditions. La mise en évidence du rôle prépondérant des conditions chimiques conduit à remettre en cause l'utilisation répandue des constantes de dégradation du premier ordre et donne des pistes pour les modèles nécessaires à une prédiction plus fine de l'atténuation naturelle.The increasing reliance on natural attenuation in dealing with contaminated sites in North America is the consequence of:1. the extremely long duration and high cost of aquifer rehabilitation by classical methods, and 2. the discovery of natural biodegradation in many different situations. However, the use of this management technique is questionable, as intrinsic biodegradation is highly dependent on chemical conditions and particularly on redox equilibria. This paper describes the role of these chemical conditions on BTEX and chlorinated solvent attenuation and, by analyzing the current research, we try to define current limits of the predictability of natural attenuation in field conditions.Natural attenuation is defined as the sum of processes able to decrease the pollutant concentration at a sampling point in an aquifer. Several physical processes such as dispersion, retardation and solubility play a role in natural attenuation. However, only biodegradation can significantly reduce the overall amount of pollutants in an aquifer, thereby allowing the pollutant concentration to reach the low levels that are required by regulations. The physical processes cited above can be modelled at a site to account for their effect, but the main focus is on biodegradation.A detailed analysis of the basic thermodynamics of redox reactions involved in biodegradation is necessary to describe the reactions that can potentially occur. A rough analysis shows that BTEX is mainly degraded by oxidation and therefore is degraded more efficiently in aerobic media. However, toluene (and sometime ethylbenzene and xylene) can be degraded by fermentation and thus degradation occurs even in methanogenic conditions. In contrast, chlorinated solvents are degraded mainly by reduction, with the exception of c-DCE (cis-dichloroethylene) and VC (vinyl chloride), which are degraded by reduction and oxidation, thus having two degradative pathways. An overall comparison of reaction rates obtained from laboratory and field experiments clearly demonstrates that under field conditions the supply of redox reactants is a limiting factor in the reaction kinetics.Degradation of BTEX under field conditions has been widely documented, and toluene ethylbenzene and xylene degradation occurred in almost all chemical environments. The most persistent product observed in almost all the studies was benzene. Due to its persistence, and also its carcinogenic and toxic properties, we focussed on the results obtained for benzene. The kinetic constant for degradation of benzene under most field conditions ranged from almost no degradation in the reduced parts of the plume to fast degradation at the oxygenated border. Degradation under nitrate, methane or iron reducing conditions was almost insignificant, but degradation did occur under sulphate reducing conditions. A detailed analysis of the data on benzene degradation under sulphate reducing conditions showed that there is a competition between bacterial populations for electron acceptors. Benzene is degraded only if electron acceptors are in excess and if no other easily degradable carbon source is present.The analysis of experimental data on chlorinated solvents is more difficult because fewer studies exist and the degradation processes are slower and more complex. Significant intrinsic biodegradation occurs mainly by reductive dechlorination, with co-metabolism being important only under modified conditions. In the field, PCE (perchloroethylene) and TCE degradation occurred only under methanogenic and sulphate reducing conditions, while c-DCE was degraded in oxygenated media and finally VC degradation occurred under almost all redox potentials. The kinetics of degradation were slow, with half-lives in the order of 1 to several years. It was shown that the variability of such constants was quite high within the same site. This variability could be explained by the availability of reducing species, particularly hydrogen. By comparing the estimated and real length of solvent plumes it was shown that biodegradation was more important than transport for the sites with the most reducing conditions. At other sites, the necessity of both methanogenic conditions and a sufficient pool of electron donors in the aquifer was demonstrated. The high toxicity of VC, when compared to TCE, was of lower concern since it was shown that the plume size was equal to or smaller than that of TCE. This was due to a fast degradation kinetics for VC observed under aerobic conditions.In conclusion, the controversy surrounding the use of models based on first-order degradation constants arose because of the strong dependence of this constant on prevailing chemical conditions. If the target at risk is far away, use of the statistics on plume length existing for BTEX seems to be sufficient. However, when the benzene content is high and the target at risk is close, there is a need to predict the size of the reduced plume. The approach is the same for more substituted chlorinated solvents. The most important data, which are often missing, are the amount of total 'easily' degradable carbon (i.e. BTEX, short chain acids or alcohols) delivered by the source that will generate the reduced plume. In order to achieve a more precise prediction, models incorporating the whole redox chain need to be developed and tested against existing field data

Nongalvanic thermometry for ultracold two-dimensional electron domains

Measuring the temperature of a two-dimensional electron gas at temperatures of a few mK is a challenging issue, which standard thermometry schemes may fail to tackle. We propose and analyze a nongalvanic thermometer, based on a quantum point contact and quantum dot, which delivers virtually no power to the electron system to be measured.Comment: 5 pages, 3 figure

Networks from gene expression time series: characterization of correlation patterns

This paper describes characteristic features of networks reconstructed from gene expression time series data. Several null models are considered in order to discriminate between informations embedded in the network that are related to real data, and features that are due to the method used for network reconstruction (time correlation).Comment: 10 pages, 3 BMP figures, 1 Table. To appear in Int. J. Bif. Chaos, July 2007, Volume 17, Issue

LATE FROST EVENTS IN AN ALPINE VALLEY: MEASUREMENTS AND CHARACTERISATION OF THE PROCESS

Under the research project GEPRI, aimed at investigating and characterizing late frost events potentiallydangerous for cultivated areas, in the spring of 2004 an intensive meteorological field experiment has been made in the Adige River Valley in Trentino (Northern Italy). The project is aimed at a better characterization of the mechanism of late frost events in complex topography in order to improve the forecast of the occurrence of nocturnal temperature minima. In this work some preliminary results of the micrometeorological measurements performed at a target area within an appletrees orchard are presented and discussed. Measurements allowed the determination of the complete energy balance, as well as the identification of specific local-scale circulations which appear to be relevant in characterizing the night-time cooling process. In case of fair weather conditions, the latter displays a sequence of at least four different phases which seem to alternate rather than superimpose advective- and radiative-effects

Vombat: An Open Source Tool for Creating Stratigraphic Logs from Virtual Outcrops

An open source tool, Vombat , is presented that is designed to operate on Virtual Outcrop Models of sedimentary rocks, with the specific aim of assisting the stratigraphic analysis and interpretation. Vombat makes it possible to estimate the average attitude of the bedding and to create one or more attitude-aligned stratigraphic reference frames. This allows Vombat to extract continuous stratigraphic logs of any property associated with the point clouds (e.g. the lidar intensity or RGB color). Stratigraphic logs produced by Vombat can be compared and correlated to typical outcrop logs and petrophysical logs obtained from boreholes (e.g. gamma ray logs) and can provide information about the lithological variations in a stratigraphic succession. Furthermore, Vombat stratigraphic reference frames can be used to associate a stratigraphic position (a depth in the stratigraphic column) to any observation made on the outcrop, allowing visualization in 3D (on the virtual outcrop model) and 1D (on a stratigraphic column) for any collected data. All the geological objects created in the virtual environment can then be saved. The tool has been developed to be user-friendly and is constituted by a dynamically loaded plugin for the open source software CloudCompare

Human–Robot Role Arbitration via Differential Game Theory

The industry needs controllers that allow smooth and natural physical Human-Robot Interaction (pHRI) to make production scenarios more flexible and user-friendly. Within this context, particularly interesting is Role Arbitration, which is the mechanism that assigns the role of the leader to either the human or the robot. This paper investigates Game-Theory (GT) to model pHRI, and specifically, Cooperative Game Theory (CGT) and Non-Cooperative Game Theory (NCGT) are considered. This work proposes a possible solution to the Role Arbitration problem and defines a Role Arbitration framework based on differential game theory to allow pHRI. The proposed method can allow trajectory deformation according to human will, avoiding reaching dangerous situations such as collisions with environmental features, robot joints and workspace limits, and possibly safety constraints. Three sets of experiments are proposed to evaluate different situations and compared with two other standard methods for pHRI, the Impedance Control, and the Manual Guidance. Experiments show that with our Role Arbitration method, different situations can be handled safely and smoothly with a low human effort. In particular, the performances of the IMP and MG vary according to the task. In some cases, MG performs well, and IMP does not. In some others, IMP performs excellently, and MG does not. The proposed Role Arbitration controller performs well in all the cases, showing its superiority and generality. The proposed method generally requires less force and ensures better accuracy in performing all tasks than standard controllers. Note to Practitioners—This work presents a method that allows role arbitration for physical Human-Robot Interaction, motivated by the need to adjust the role of leader/follower in a shared task according to the specific phase of the task or the knowledge of one of the two agents. This method suits applications such as object co-transportation, which requires final precise positioning but allows some trajectory deformation on the fly. It can also handle situations where the carried obstacle occludes human sight, and the robot helps the human to avoid possible environmental obstacles and position the objects at the target pose precisely. Currently, this method does not consider external contact, which is likely to arise in many situations. Future studies will investigate the modeling and detection of external contacts to include them in the interaction models this work addresses