Simulations of Contrail Optical Properties and Radiative Forcing for Various Crystal Shapes

The aim of this study is to investigate the sensitivity of radiative-forcing computations to various contrail crystal shape models. Contrail optical properties in the shortwave and longwave ranges are derived using a ray-tracing geometric method and the discrete dipole approximation method, respectively. Both methods present good correspondence of the single-scattering albedo and the asymmetry parameter in a transition range (3–8 µm). There are substantial differences in single-scattering properties among 10 crystal models investigated here (e.g., hexagonal columns and plates with different aspect ratios, and spherical particles). The single-scattering albedo and the asymmetry parameter both vary by up to 0.1 among various crystal shapes. The computed single-scattering properties are incorporated in the moderate-resolution atmospheric radiance and transmittance model(MODTRAN) radiative transfer code to simulate solar and infrared fluxes at the top of the atmosphere. Particle shapes have a strong impact on the contrail radiative forcing in both the shortwave and longwave ranges. The differences in the net radiative forcing among optical models reach 50% with respect to the mean model value. The hexagonal-column and hexagonal-plate particles show the smallest net radiative forcing, and the largest forcing is obtained for the spheres. The balance between the shortwave forcing and longwave forcing is highly sensitive with respect to the assumed crystal shape and may even change the sign of the net forcing. The optical depth at which the mean diurnal radiative forcing changes sign from positive to negative varies from 4.5 to 10 for a surface albedo of 0.2 and from 2 to 6.5 for a surface albedo of 0.05. Contrails are probably never that optically thick (except for some aged contrail cirrus), however, and so will not have a cooling effect on climate

Testing patients with non-specific symptoms for antibodies against Borrelia burgdorferi sensu lato does not provide useful clinical information about their aetiology

AbstractThe aim of this study was to determine whether patients with antibodies against Borrelia burgdorferi sensu lato or who report a history of erythema migrans (EM) or tick bite are more likely to have non-specific symptoms such as musculoskeletal pain, fatigue, sensory disorder, and headache. The study group comprised 423 subjects with non-specific symptoms tested for antibodies against B. burgdorferi sensu lato between July 2012 and December 2014 because of suspicion of Lyme borreliosis (LB). Of these, 285 were females (67%) and 138 were males (33%); the median age was 53 years (range, 7–89 years). Patients with a confirmed diagnosis of LB and patients with a known underlying disease that could influence the development of the symptoms were excluded from the evaluation. Subjects were assigned to the seronegative group or to one of three seropositive groups, and the history of EM and tick bite was also recorded. Statistical analysis was performed with single chi-square tests of independence and multiple logistic regression models. No differences in the occurrence of non-specific symptoms were observed between patients grouped according to antibody status. A history of EM showed no significant effect on any of the non-specific symptoms. A history of tick bite was weakly correlated with joint pain and joint swelling (p <0.05). In conclusion, it is highly unlikely that the complaints are related to a previous infection with B. burgdorferi sensu lato. The results show that testing patients with non-specific symptoms for antibodies against B. burgdorferi sensu lato in the everyday clinical setting does not provide any useful information about their aetiology

Conditions influencing incoming global solar radiation in Hornsund (Spitsbergen) in spring 2015

This article analyses the conditions affecting the incoming global solar radiation in Hornsund (Spitsbergen) in spring of 2015. Incoming solar radiation turned out to be average for the season under analysis, as compared with longer-term data. The clearness index (KT) was 0.46, and was mainly determined by the extent of cloudiness. As a result of differences in the length of day, sunshine duration in May was greater than in April. Incoming solar radiation to the earth’s surface is also affected by the atmospheric optical properties. The average value of aerosol optical depth (AOD) at 500 nm in Hornsund in spring of 2015 was 0.087. In the analysed period, increased values of AOD at 500 nm (up to 0.143) were observed, although these are not record values. Over April and May, the greatest part of optical depth was comprised of anthropogenic aerosols (41%), followed by marine aerosols (26%), desert dust (21%) and biomassburning aerosols (12%). This indicates the significant role of the anthropogenic factor in the climatic conditions of Spitsbergen

Comparison of the Linke turbidity factor in Warsaw and in Belsk

The article describes the relationship between direct solar radiation in a city (Warsaw) and in its broadly-defined suburban area (Belsk). The analysis covers the days of 1969-2003 when observations were carried out at both sites. The degree of extinction of solar radiation was expressed by means of Linke’s turbidity factor. Its mean annual value on the selected days of the period under consideration was 3.00± 0.10 at Warsaw and 3.00±0.11 at Belsk. Any differences in the atmospheric turbidity between the Warsaw site and Belsk in individual seasons of the year were marginal and within the error margin of Linke’s factor. The period considered was also divided into two sub-periods (1969-1993 and 1994-2003), in which atmospheric turbidity in Warsaw and in Belsk was compared by individual seasons and whole years. At both analysed sites Linke’s atmospheric turbidity factor decreased in 1994-2003, compared to the values for the earlier sub-period (1969-1993). The differences in atmospheric turbidity between the Warsaw site and Belsk are small and often statistically insignificant. The reason for this is, perhaps, the location of the urban measurement site far from the city centre, even though the site was still situated in a typically urban environment

Metformin and Its Sulfenamide Prodrugs Inhibit Human Cholinesterase Activity

The results of epidemiological and pathophysiological studies suggest that type 2 diabetes mellitus (T2DM) may predispose to Alzheimer’s disease (AD). The two conditions present similar glucose levels, insulin resistance, and biochemical etiologies such as inflammation and oxidative stress. The diabetic state also contributes to increased acetylcholinesterase (AChE) activity, which is one of the factors leading to neurodegeneration in AD. The aim of this study was to assess in vitro the effects of metformin, phenformin, and metformin sulfenamide prodrugs on the activity of human AChE and butyrylcholinesterase (BuChE) and establish the type of inhibition. Metformin inhibited 50% of the AChE activity at micromolar concentrations (2.35 μmol/mL, mixed type of inhibition) and seemed to be selective towards AChE since it presented low anti-BuChE activity. The tested metformin prodrugs inhibited cholinesterases (ChE) at nanomolar range and thus were more active than metformin or phenformin. The cyclohexyl sulfenamide prodrug demonstrated the highest activity towards both AChE (IC50 = 890 nmol/mL, noncompetitive inhibition) and BuChE (IC50 = 28 nmol/mL, mixed type inhibition), while the octyl sulfenamide prodrug did not present anti-AChE activity, but exhibited mixed inhibition towards BuChE (IC50 = 184 nmol/mL). Therefore, these two bulkier prodrugs were concluded to be the most selective compounds for BuChE over AChE. In conclusion, it was demonstrated that biguanides present a novel class of inhibitors for AChE and BuChE and encourages further studies of these compounds for developing both selective and nonselective inhibitors of ChEs in the future

Lidar Measurements of Canadian Forest Fire Smoke Episode Observed in July 2013 over Warsaw, Poland

This paper presents a preliminary study of aerosol optical properties of air-mass advected on 10th July 2013 from Canada above Warsaw, Poland, during the forest fire event that occurred in Quebec at the beginning of July 2013. The observations were conducted with use of the modern version of 8-channel PollyXT lidar capable of measuring at 3β+2α+2δ+VW and interpreted with available information from the MACC model, the CALIPSO and MODIS satellite sensors, the AERONET data products and the data gathered within the Poland-AOD network

Near-range receiver unit of next generation PollyXT used with Koldeway aerosol Raman lidar in Arctic

The Near-range Aerosol Raman lidar (NARLa) receiver unit, that was designed to enhance the detection range of the NeXT generation PollyXT Aerosol-Depolarization-Raman (ADR) lidar of the University of Warsaw, was employed next the Koldeway Aerosol Raman Lidar (KARL) at the AWI-IPEV German-French station in Arctic during Spring 2015. Here we introduce shortly design of both lidars, the scheme of their installation next to each other, and preliminary results of observations aiming at arctic haze investigation by the lidars and the iCAP a set of particle counter and aethalometer installed under a tethered balloon

Volatile compounds in the thermoplastic extrusion of bovine rumen

The volatile compounds of raw and extruded bovine rumen, extracted by dynamic headspace, were separated by gas chromatography and analyzed by GC-MS. Raw and extruded materials presented thirty-two volatile compounds. The following compounds were identified in raw bovine rumen: heptane, 1-heptene, 4-methyl-2-pentanone, toluene, hexanal, ethyl butyrate, o-xylene, m-xylene, p-xylene, heptanal, limonene, nonanal, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane and octadecane. The following compounds were identified in the extruded material: 1-heptene, 2,4-dimethylhexane, toluene, limonene, undecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane and nonadecane. Mass spectra of some unidentified compounds indicated the presence of hydrocarbons with branched chains or cyclic structure.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

SAWA experiment ? properties of mineral dust aerosol as seen by synergic lidar and sun-photometer measurements

International audienceWe propose a method of retrieving basic information on mineral dust aerosol particles from synergic sun-photometer and multi-wavelength lidar measurements as well as from the observations of lidar light depolarisation. We use this method in a case study of mineral dust episode in Central Europe. Lidar signals are inversed with a modified Klett-Fernald algorithm. Aerosol optical depth measured with the sun-photometer allows to reduce uncertainties in the inversion procedure through which we estimate vertical profile of aerosol extinction. Next we assume that aerosol particles may be represented by ensemble of randomly oriented, identical spheroids. Having calculated vertical profiles of aerosol extinction coefficients for lidar wavelengths, we compute the profiles of local Angstrom exponent. We use laser beam depolarisation together with the calculated Angstrom exponents to estimate the shapes (aspect ratios) and sizes of the spheroids. Numerical calculations are performed with the transition matrix (T-matrix) algorithm by M. Mishchenko. The proposed method was first used during SAWA measurement campaign in Warsaw, spring 2005, to characterise the particles of desert dust, drifting over Poland with a southern-eastern wind (13?14 April). Observations and T-matrix calculations show that mode radii of spheroids representative for desert aerosols' particles are in the range of 0.15?0.3 ?m, while their aspect ratios are lower than 0.7 or larger than 1.7