A Monolithic Time Stretcher for Precision Time Recording

Identifying light mesons which contain only up/down quarks (pions) from those containing a strange quark (kaons) over the typical meter length scales of a particle physics detector requires instrumentation capable of measuring flight times with a resolution on the order of 20ps. In the last few years a large number of inexpensive, multi-channel Time-to-Digital Converter (TDC) chips have become available. These devices typically have timing resolution performance in the hundreds of ps regime. A technique is presented that is a monolithic version of ``time stretcher'' solution adopted for the Belle Time-Of-Flight system to address this gap between resolution need and intrinsic multi-hit TDC performance.Comment: 9 pages, 15 figures, minor corrections made, to appear as JINST_008

Field observations about the behaviour of codling-moth in Trentino (North-Eastern Italy)

Codling-moth and applescab are the most important pathogens in both conventional and organic apple productions. In order to control any phytopathological problem, it is important to improve the knowledge of the behaviour of each specific pest. Since several years (starting from 1986) we are improving in Trentino (North-Eastern Italy) the observations of the population dynamics of codling-moth in order to find the best way to control and treat this pest insect. Constant monitoring and the knowledge of the characteristics of the different compounds and possible methods to control the codling-moth (mating disruption, granulose virus and specific nematodes) represent the most important basis to organize an effective controlstrategy

Wetlands: A potentially significant source of atmospheric methyl bromide and methyl chloride

Tropospheric methyl bromide (CH3Br) and methyl chloride (CH3Cl) are significant sources of ozone (O3) destroying halogens to the stratosphere. Their O3 depletion potential (ODP) can be determined from atmospheric lifetimes and therefore their atmospheric budgets, both of which are out of balance with known sink terms larger than identified sources. We have discovered a new source of CH3Br and CH3Cl emissions to the atmosphere at two wetland sites in the Northeastern United States. We have reason to believe that these compounds are biologically produced in situ. Our measurements indicate that the global annual flux of CH3Br and CH3Cl from wetlands could be as high as 4.6 Gg yr−1 Of CH3Br and 48 Gg yr−1 of CH3Cl. These are preliminary estimates based on measurements made during the end of the 1998 growing season, a time period of decreased emissions of other trace gases such as methane (CH4)

Longer thaw seasons increase nitrogen availability for leaching during fall in tundra soils

Climate change has resulted in warmer soil temperatures, earlier spring thaw and later fall freeze-up, resulting in warmer soil temperatures and thawing of permafrost in tundra regions. While these changes in temperature metrics tend to lengthen the growing season for plants, light levels, especially in the fall, will continue to limit plant growth and nutrient uptake. We conducted a laboratory experiment using intact soil cores with and without vegetation from a tundra peatland to measure the effects of late freeze and early spring thaw on carbon dioxide (CO2) exchange, methane (CH4) emissions, dissolved organic carbon (DOC) and nitrogen (N) leaching from soils. We compared soil C exchange and N production with a 30 day longer seasonal thaw during a simulated annual cycle from spring thaw through freeze-up and thaw. Across all cores, fall N leaching accounted for ~33% of total annual N loss despite significant increases in microbial biomass during this period. Nitrate $({{{\rm{NO}}}_{3}}^{-})$ leaching was highest during the fall (5.33 ± 1.45 mg N m−2 d−1) following plant senescence and lowest during the summer (0.43 ± 0.22 mg N m−2 d−1). In the late freeze and early thaw treatment, we found 25% higher total annual ecosystem respiration but no significant change in CH4 emissions or DOC loss due to high variability among samples. The late freeze period magnified N leaching and likely was derived from root turnover and microbial mineralization of soil organic matter coupled with little demand from plants or microbes. Large N leaching during the fall will affect N cycling in low-lying areas and streams and may alter terrestrial and aquatic ecosystem nitrogen budgets in the arctic

An estimate of the uptake of atmospheric methyl bromide by agricultural soils

Published estimates of removal of atmospheric methyl bromide (CH3Br) by agricultural soils are 2.7 Gg yr−1 (Gg = 109 g) [Shorter et al., 1995] and 65.8 Gg yr−1 [Serça et al., 1998]. The Serça et al. estimate, if correct, would suggest that the current value for total removal of atmospheric CH3Br by all sinks of 206 Gg yr−1 (based on Shorter et al., 1995) would be 30% too low. We have calculated a new rate of global agricultural soil uptake of atmospheric CH3Br from a larger sampling of cultivated soils collected from 40 sites located in the United States, Costa Rica, and Germany. First order reaction rates were measured during static laboratory incubations. These data were combined with uptake measurements we reported earlier based on field and laboratory experiments [Shorter et al. 1995]. Tropical (10.2°–10.4°N) and northern (45°–61°N) soils averaged lower reaction rate constants than temperate soils probably due to differing physical and chemical characteristics as well as microbial populations. Our revised global estimate for the uptake of ambient CH3Br by cultivated soils is 7.47±0.63 Gg yr−1, almost three times the value that we reported in 1995

Controls on the seasonal exchange of CH3Br in temperate peatlands

Measurements of CH3Br exchange at two New Hampshire peatlands (Sallie\u27s Fen and Angie\u27s Bog) indicate that net flux from these ecosystems is the sum of competing production and consumption processes. Net CH3Br fluxes were highly variable and ranged from net emission to net uptake between locations within a single peatland. At Sallie\u27s Fen, net CH3Br flux exhibited positive correlations with peat temperature and air temperature during all seasons sampled, but these relationships were not observed at Angie\u27s Bog where flux varied according to microtopography. The major CH3Br production process at Sallie\u27s Fen appeared dependent on aerobic conditions within the peat, while CH3Br production at Angie\u27s Bog was favored by anaerobic conditions. There was evidence of aerobic microbial consumption of CH3Br within the peat at both sites. In a vegetation removal experiment conducted at Sallie\u27s Fen with dynamic chambers, all collars exhibited net consumption of CH3Br. Net CH3Br flux had a negative correlation with surface temperature and a positive correlation with water level in collars with all vegetation clipped consistent with aerobic microbial consumption. Vegetated collars showed positive correlations between net CH3Br flux and air temperature. A positive correlation between net CH3Br flux and surface temperature was also observed in collars in which all vegetation except Sphagnum spp. were clipped. These correlations are consistent with seasonal relationships observed in 1998, 1999, and 2000 and suggest that plants and/or fungi are possible sources of CH3Br in peatlands. Estimates of production and consumption made on two occasions at Sallie\u27s Fen suggest that peatlands have lower rates of CH3Br consumption compared to upland ecosystems, but a close balance between production and consumption rates may allow these wetlands to act as either a net source or sink for this gas

Production of methyl bromide in a temperate forest soil

Field enclosure measurements of a temperate forest soil show net uptake of ambient methyl bromide (CH3Br), an important trace gas in both tropospheric and stratospheric ozone cycling. The net flux for 1999 was estimated to be −168 ± 72 μg CH3Br m−2 (negative indicates loss from the atmosphere). Individual enclosure flux measurements ranged from −4.0 to +3.3 μg CH3Br m−2 d−1. Soil consumption of CH3Br was estimated from laboratory soil incubations. Production of CH3Br was calculated as the difference between net flux and predicted consumption. Fungi could be responsible for the production of CH3Br in this temperate forest soil

Timescale dependence of environmental and plant‐mediated controls on CH4 flux in a temperate fen

This study examined daily, seasonal, and interannual variations in CH4 emissions at a temperate peatland over a 5‐year period. We measured net ecosystem CO2 exchange (NEE), CH4 flux, water table depth, peat temperature, and meteorological parameters weekly from the summers (1 May to 31 August) of 2000 through 2004 at Sallie\u27s Fen in southeastern New Hampshire, United States. Significant interannual differences, driven by high variability of large individual CH4 fluxes (ranging from 8.7 to 3833.1 mg CH4 m−2 d−1) occurring in the late summer, corresponded with a decline in water table level and an increase in air and peat temperature. Monthly timescale yielded the strongest correlations between CH4 fluxes and peat and air temperature (r2 = 0.78 and 0.74, respectively) and water table depth (WTD) (r2 = 0.53). Compared to daily and seasonal timescales, the monthly timescale was the best timescale to predict CH4 fluxes using a stepwise multiple regression (r2 = 0.81). Species composition affected relationships between CH4 fluxes and measures of plant productivity, with sedge collars showing the strongest relationships between CH4 flux, water table, and temperature. Air temperature was the only variable that was strongly correlated with CH4 flux at all timescales, while WTD had either a positive or negative correlation depending on timescale and vegetation type. The timescale dependence of controls on CH4 fluxes has important implications for modeling

Endotoxin enhancement as a possible etiology of early-onset group B beta-hemolytic streptococcal sepsis in the newborn.

Journal ArticleGroup B streptococcal cells, either viable or heat-killed, contain a substance that induced fever in rabbits with maximal responses occurring four hours after intravenous injection. In contrast, supernatant fluids failed to induce significant fever. Group B streptococcal cells also enhanced host susceptibility to lethal shock by endotoxin as much as 40,000-fold. A graph of log streptococcal cell dose used for pretreatment versus log LD50 endotoxin gave a straight line with a slope of approximately -1. Rabbits that received both streptococcal cells and endotoxin showed initial fever followed by hypothermia, labored breathing, watery diarrhea, evidence of vascular collapse, and finally death. Animals that received streptococcal cells or endotoxin alone showed only fevers and mild diarrhea. A possible theory for the cause of death in the neonate infected with group B streptococci is presented