Period October-November Research Articles

Origin and transport of tropical cirrus clouds observed over Paramaribo, Suriname (5.8°N, 55.2°W)

The Intertropical Convergence Zone (ITCZ) passes twice a year over tropical Suriname, bringing two wet and two dry seasons. During a pilot study campaign in Suriname, cirrus clouds were observed with a mobile aerosol Raman lidar (MARL) and with balloon sondes containing a frost point hygrometer called Snow White, over the period October–November 2004. These observations are used to study the origin of cirrus clouds and the dynamical processes that determine their transport, using European Centre for Medium‐Range Weather Forecasts (ECMWF) operational analyses. The height of cirrus occurrence is in phase with the height of the cold point tropopause, with maximum heights occurring during Northern Hemisphere winter that are about 2 km above the minimum values in summertime. The occurrence of cirrus often corresponds with a northerly meridional wind flow (in a layer underneath the tropopause), also when the ITCZ lies to the south in the period January–May. ECMWF analyses point out that inertial instability flow, in the form of vertically stacked meridional circulation cells in the upper troposphere (UT), can explain the transport of these cirrus events. Also evident is that radiative cooling of a moist layer transported in the UT leads to a thermal wind in the form of an easterly/westerly jet associated with the southward/northward transport of moist air. An interactive play between the inertial instability and thermal wind mechanisms explains many of the observed features of cirrus occurrence over Suriname. The observed cirrus mostly originates from the ITCZ or from deep convective centers to the south that form during the early summer monsoon.

Effect of propagation material on some quality attributes of strawberry fruit ( Fragaria x ananassa, var. Selva)

In the Mediterranean region, cold-stored plants (summer planting system) are used as the main strawberry planting material (plant establishing period July–August). However, recently fresh plants (winter planting system) have also started being used for strawberry production (plant establishing period October–November). As the plantations originated from cold-stored or fresh plants differ in plant growth and yield, some differences in fruit quality have also been expected; therefore, the objective of the current study was to compare fruit quality of plants originated from different propagation material. Cold-stored plants were well developed before the beginning of the spring harvest, while fresh plants continued growth concomitantly with fruiting. The harvesting period of cold-stored plants lasted 4–6 weeks (second week of April–second half of May). Fresh plants produced fewer and larger fruits than cold-stored plants, but for a longer harvest period, which lasted throughout all summer. Differences in soluble solids and dry matter content between the fruits from cold-stored and fresh plants were observed in the first three sampling dates in both years of the experiment. In some sampling dates, significant differences in anthocyanin, titratable acidity and ascorbic acid content, were observed between fruits of plants originated from different propagation material.

High-Resolution Rainfall Estimation from X-Band Polarimetric Radar Measurements

Abstract The paper presents a rainfall estimation technique based on algorithms that couple, along a radar ray, profiles of horizontal polarization reflectivity (ZH), differential reflectivity (ZDR), and differential propagation phase shift (ΦDP) from X-band polarimetric radar measurements. Based on in situ raindrop size distribution (DSD) data and using a three-parameter “normalized” gamma DSD model, relationships are derived that correct X-band reflectivity profiles for specific and differential attenuation, while simultaneously retrieving variations of the normalized intercept DSD parameter (Nw). The algorithm employs an iterative scheme to intrinsically account for raindrop oblateness variations from equilibrium condition. The study is facilitated from a field experiment conducted in the period October–November 2001 in Iowa City, Iowa, where observations from X-band dual-polarization mobile radar (XPOL) were collected simultaneously with high-resolution in situ disdrometer and rain-gauge rainfall meas...

Mite allergen (Der p 1) levels in houses of children with atopic dermatitis: the relationship with allergometric tests.

Several studies, in particular in adult groups, have evaluated the involvement of mites in the pathogenesis of atopic dermatitis (AD). This still remains controversial. The objective of this study was to determine the level of house dust mites (HDMs) in the beds of a group of children with AD and correlate these levels with their allergometric assessment. Forty-one children with AD underwent allergometric tests (prick test, patch test and radioallergosorbent test, RAST) and the concentration levels of HDMs in their homes were evaluated. Our data show that about half of the children (51%) with AD presented Dermatophagoides pteronyssinus positivity (prick test and/or RAST and/or patch test). Dust was collected in the period October-November from the children's beds, by the same two operators, using a dust-collection device. The dust mite level was tested by an enzyme-linked immunosorbent assay with antibody against Der p 1 allergen. Ten children (24%) presented a Der p 1 concentration > 2 microgram/g of dust (the value assumed to be a risk level for sensitization), 20 (49%) between 0.1 and 2 microgram/g and 11 (27%) < 0.1 microgram/g of dust. In the group with the highest Der p 1 concentration (> 2 microgram/g dust) nine children (90%) presented an allergometric D. pteronyssinus sensitivity, the difference with the other two groups being statistically significant at P < 0.018. The results of the present study show that the highest HDM concentrations were observed in the group with an allergometric D. pteronyssinus positivity (prick test and/or RAST and/or patch test). It is hypothesized that a higher HDM concentration may elicit D. pteronyssinus IgE sensitization and delayed hypersensitivity in children with AD.

A study of processes affecting the uptake of contaminants by intertidal sediments, using the radioactive tracers: 7Be, 137Cs and unsupported 210Pb

The vertical distribution of the radio-nuclides 7Be, 137Cs and unsupported 210Pb were used to describe the processes of accretion, mixing, mixing depth and focusing, that influence the responses of intertidal bed sediments to contaminant inputs. These processes were studied in the mid and lower Tamar Estuary at six different sites sampled on eight occasions, over a period of 2 years. The maximum depth to which sediment deposits were mixed ranged from 10 cm to greater than 40 cm. Mixing coefficients derived from the 7Be and unsupported 210Pb profiles ranged from 0·56 × 10 −7 to 34·2 × 10 −7 cm 2 s −1. The sediment inventories of 7Be, 137Cs and unsupported 210Pb, the maximum depths of mixing and the mixing coefficients were significantly higher in the bed sediments of the creek site and at two sites situated 12–14 km up the estuary than those observed at sites situated nearer to the seaward end of the estuary. With the exception of the site closest to the mouth of the estuary, the 7Be inventory at all sites was consistently higher during the period October–November than during the period March–September. Using data derived from the 7Be and unsupported 210Pb sediment profiles, the profiles of 137Cs were simulated and compared with the observed data recorded at each site.

Observations of gravity waves from multispectral mesospheric nightglow emissions observed at 23°S

Simultaneous measurements of the 015 57.7 nm, O 2 atmospheric (0,1) band, NaD and OH (9,4) band emissions obtained during the period October November 1989 at Cachoeira Paulista (23°S, 45°W), Brazil, have been analysed to study gravity waves in the mesospheric region at a low-latitude station in the southern hemisphere. It was found that, when these emissions showed large temporal intensity variations, there were also short period quasi-coherent temporal variations superposed on them, suggesting a possible passage of internal gravity waves in the emission layers. Cross-correlation analysis indicates that the time lag between the different emissions is smaller for short period variations compared with the long period variations. The wave parameters, namely a vertical wavelength of 12 km, a horizontal derived wavelength of 200 km with a period of 80 min, estimated from one of the observed short-period coherent oscillations, are typical of the internal gravity waves at the airglow emission height.

Collision frequency of electrons in the F-region

Abstract The electronic collision frequency at the peak of the F -layer has been measured at Delhi (Geog. Lat. 28°38′N; Geog. Long. 77°13′E) near the time of ground sunrise using the fixed frequency method first employed by Farmer and Ratcliffe (1935). The mean of 42 measurements made during the period October–November 1967, is found to be (3.9 ± 0.2) × 10 3 sec −1 referring to a mean true-height of (290 ± 20) km.

EVOLUTIONARY CHANGES IN MYXOMA VIRUS IN BRITAIN. AN EXAMINATION OF 222 NATURALLY OCCURRING STRAINS OBTAINED FROM 80 COUNTIES DURING THE PERIOD OCTOBER-NOVEMBER 1962.

Samples of lesions containing viable myxoma virus were collected from 222 infected wild rabbits captured in 80 counties of Britain during October–November 1962. They were dispatched by air to Australia and passaged once in domestic rabbits before being tested for their virulence by the intradermal inoculation of groups of six laboratory rabbits with small doses of virus.The results showed that a wide range of viruses of differing properties now coexist in Britain. Their virulence ranges from very high (99 % lethal) to low (about 50 %), but the majority of strains fall into the grade III virulence group, with estimated case mortality rates varying between 70 and 95%. The viruses also produce disease of varying symptomatology, skin lesions being very prominent, raised or flat. There was no obvious association between lesion type and virulence.Tests made on the wild rabbits from which the samples were obtained, and on Inoculated domestic rabbits, showed that virulence could not be predicted by gel-diffusion tests.