DO METEOROLOGISTS SUPPRESS THUNDERSTORMS? Radar-Derived Statics and the Behavior of Moist Convection

Most meteorologists are acquainted with the no- tion of a weather hole—that is, a place that receives less exciting weather than does its surroundings. Exciting weather takes many forms, but when people use the term weather hole, they tend to mean a place that thunderstorms often barely miss, or near which approaching storms often dissipate. For this paper, that is the meaning we adopt. In our experience, many meteorologists and lay weather enthusiasts genuinely believe that they live in weather holes, and this belief, almost without fail, seems to stem from countless hours spent gazing at displays of radar reflectivity. We have generally presumed that such people simply relish thunderstorms, are memorably disappointed whenever storms miss them, and erroneously conclude that their locations are subject to some kind of meteorologic disfavor. The recent availability of multiple years\u27 worth of national radar composites from the Weather Surveillance Radar-1988 Doppler (WSR-88D) network makes it possible to address objectively, if not definitively, whether meteorologists appear to live in weather holes and whether such an appearance is physical or artificial

IRF4 and BATF are critical for CD8(+) T-cell function following infection with LCMV.

CD8(+) T-cell functions are critical for preventing chronic viral infections by eliminating infected cells. For healthy immune responses, beneficial destruction of infected cells must be balanced against immunopathology resulting from collateral damage to tissues. These processes are regulated by factors controlling CD8(+) T-cell function, which are still incompletely understood. Here, we show that the interferon regulatory factor 4 (IRF4) and its cooperating binding partner B-cell-activating transcription factor (BATF) are necessary for sustained CD8(+) T-cell effector function. Although Irf4(-/-) CD8(+) T cells were initially capable of proliferation, IRF4 deficiency resulted in limited CD8(+) T-cell responses after infection with the lymphocytic choriomeningitis virus. Consequently, Irf4(-/-) mice established chronic infections, but were protected from fatal immunopathology. Absence of BATF also resulted in reduced CD8(+) T-cell function, limited immunopathology, and promotion of viral persistence. These data identify the transcription factors IRF4 and BATF as major regulators of antiviral cytotoxic T-cell immunity

Partial joint processing with efficient backhauling using particle swarm optimization

In cellular communication systems with frequency reuse factor of one, user terminals (UT) at the cell-edge are prone to intercell interference. Joint processing is one of the coordinated multipoint transmission techniques proposed to mitigate this interference. In the case of centralized joint processing, the channel state information fed back by the users need to be available at the central coordination node for precoding. The precoding weights (with the user data) need to be available at the corresponding base stations to serve the UTs. These increase the backhaul traffic. In this article, partial joint processing (PJP) is considered as a general framework that allows reducing the amount of required feedback. However, it is difficult to achieve a corresponding reduction on the backhaul related to the precoding weights, when a linear zero forcing beamforming technique is used. In this work, particle swarm optimization is proposed as a tool to design the precoding weights under feedback and backhaul constraints related to PJP. The precoder obtained with the objective of weighted interference minimization allows some multiuser interference in the system, and it is shown to improve the sum rate by 66% compared to a conventional zero forcing approach, for those users experiencing low signal to interference plus noise ratio

THE MATERHORN: Unraveling the Intricacies of Mountain Weather

Emerging application areas such as air pollution in megacities, wind energy, urban security, and operation of unmanned aerial vehicles have intensified scientific and societal interest in mountain meteorology. To address scientific needs and help improve the prediction of mountain weather, the U.S. Department of Defense has funded a research effort—the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) Program—that draws the expertise of a multidisciplinary, multi-institutional, and multinational group of researchers. The program has four principal thrusts, encompassing modeling, experimental, technology, and parameterization components, directed at diagnosing model deficiencies and critical knowledge gaps, conducting experimental studies, and developing tools for model improvements. The access to the Granite Mountain Atmospheric Sciences Testbed of the U.S. Army Dugway Proving Ground, as well as to a suite of conventional and novel high-end airborne and surface measurement platforms, has provided an unprecedented opportunity to investigate phenomena of time scales from a few seconds to a few days, covering spatial extents of tens of kilometers down to millimeters. This article provides an overview of the MATERHORN and a glimpse at its initial findings. Orographic forcing creates a multitude of time-dependent submesoscale phenomena that contribute to the variability of mountain weather at mesoscale. The nexus of predictions by mesoscale model ensembles and observations are described, identifying opportunities for further improvements in mountain weather forecasting

NITROGENASE ACTIVITY OF COWPEA (<i>Vigna unguiculata</i> (L.) Walp.) DURING AND AFTER DROUGHT STRESS

Greenhouse experiments were conducted with the objectives (1) to investigate the nitrogenase activity (NA) of cowpea (Vigna unguiculata (L.) Walp.) root nodules during the development of and subsequent recovery from drought stress and (2) to determine whether the changes in NA during and following drought stress are related to nodule water potential. Nitrogenase activity of root nodules decreased by more than 80% within 6–8 d of withholding water and recovered 1 or 2 d after watering. Nodule water potential declined significantly from approximately −0.2 MPa to −0.48 MPa with 8 d of stress and recovered to prestress levels within 24 h after watering. Midday abaxial stomatal conductance decreased significantly with stress but recovered within 24 h following watering. Midday leaf water potential did not change significantly during the experimental period. Nodule NA declined 2 d before that of nodule water potential in apparent response to declining soil water content. This response and the lag in the recovery of NA following drought stress after nodule water potential had returned to prestress levels support the hypothesis that nodule water potential per se is not the primary cause for the decline in NA of cowpea root nodules during drought stress.Key words: Vigna unguiculata (L.) Walp., nitrogenase activity, drought stress, recovery, cowpea </jats:p

NITROGENASE ACTIVITY, PHOTOSYNTHESIS AND TOTAL NONSTRUCTURAL CARBOHYDRATES IN COWPEA DURING AND AFTER DROUGHT STRESS

Greenhouse experiments were conducted to determine whether depressed nitrogenase activity (NA) of cowpea (Vigna unguiculata (L.) Walp.) nodules during drought stress is associated with altered carbohydrate supply to the nodules. Nitrogenase activity of the nodules, midday abaxial stomatal conductance, leaf net photosynthesis and mg total nonstructural carbohydrate (TNC) g−1 dry weight of several plant parts were measured in cowpea subjected to and recovering from drought stress periods of 0, 4 and 8 days. In addition, cowpea plants were shaded or partially defoliated (75% leaf removal) to limit carbohydrate supply to the nodules of well-watered plants. Stomatal conductance, leaf net photosynthesis and nodule NA declined 60, 62 and 90%, respectively, within 4 d of withholding water. After 8 d of drought stress, leaf net photosynthesis and nodule NA were near zero. Stomatal conductance and leaf net photosynthesis returned to the level of unstressed plants within 24 h following rewatering while recovery of NA was delayed. Shading and defoliation of cowpea plants under well watered conditions decreased NA 62 and 44%, respectively. TNC concentrations of leaves, petioles, stems, roots and nodules did not differ appreciably between drought stressed and control plants. In contrast, TNC concentrations of shoot plant parts from shaded or defoliated plants declined significantly compared to controls and nodule TNC concentrations declined in shaded plants. The decline in NA by cowpea nodules during drought stress did not appear to be directly associated with carbohydrate supply to the nodules, but rather the result of a new equilibrium attained with overall limited plant growth under the stress.Key words: Vigna unguiculata (L.) Walp., nitrogenase activity, drought stress recovery, assimilate stress, shading, defoliation, total nonstructural carbohydrate </jats:p