Unexpected vertical profiles over complex terrain due to the incomplete formulation of transport processes in the SAIMM/UAM-V air quality model

The air quality model (AQM) package SAIMM/UAM-V Systems Applications International Mesoscale Model/Urban Airshed Model with Variable grid was applied to a domain with complex topography including Switzerland. The output pressure at a fixed height above sea level generated by one of the SAIMM post-processor showed unexpected variations of about 40 hPa over the domain. We found that these fluctuations were caused by an incorrect definition of the pressure reference height. After the change of this definition, realistic pressure values were obtained. Using the correct pressure field as input, we simulated the 3-dimensional mixing ratios of pollutants with UAM-V for the summer smog period of July 28–29, 1993. The values tended to increase with height above the surface and with surface elevation above sea level. The Swiss topography was mirrored in the mixing ratio fields. By using CO as a quasi-inert tracer, it became evident that transport phenomena such as advection and diffusion did not consider expansions or compressions due to pressure and temperature variations. After the conversion of the concentrations to a common reference pressure and temperature before the calculation of transport, these strange topographic features in the mixing ratios vanished completely. The CO mixing ratio was underestimated by 10–15 ppb (7–10%) in the lowest layer over the Swiss Plateau due the omission of compression or expansion. For O₃ and NO₂, the differences were 0–5 ppb (0–10%) and 0–0.2 ppb (0–15%), respectively.     

Chip-based multimodal super-resolution microscopy for histological investigations of cryopreserved tissue sections

Histology involves the observation of structural features in tissues using a microscope. While diffraction-limited optical microscopes are commonly used in hist...     

High-Speed Flow Sensing as A Diagnostic Tool in the Development of Microfluidic Systems

Seyonic is developing a family of high-speed micro flow sensors with full-scale sensitivities between 0.25 and 10 microliter per second. The flow rate is determined by the measurement of a pressure difference across a fluidic restriction, using two integrated piezo-resistive pressure sensors. Main applications are in sub-microliter dispensing systems, where both sensor accuracy and speed provide real-time validation of the requested liquid volumes. The very fast response of the sensor, less than 2 ms, allows for measurement of liquid volumes down to the nL range. The sensor is able to measure not only the flow, but also the instantaneous pressure in the systems under evaluation. It is therefore possible to obtain valuable information on the system's operation for the characterization of fluidic components such as micromachined pumps, solenoid valves and jet dispensers     

The collision channel with recovery

We consider a simple conceptual model of random accessing to a receiver deploying multiuser detection techniques. The model is a simple extension of Massey and Mathys' collision channel without feedback in which a certain probability of recovery from collision is introduced. As the main result, we derive the slot-synchronized capacity region of this recovery channel and show that for sufficiently powerful multiuser detectors, maximal performance is achieved without any sophisticated transmission protocols. We also explore the effect of a simple fading model.     

Urinary indices in llamas fed different diets

Indices of renal function and damage were measured in 12 healthy male adult llamas fed a diet of mixed alfalfa/grass hay (mixed hay) and water ad libitum. Using a collection bag fitted over the preputial area, urine samples were collected at 6, 12, and 24 hours. Serum samples were obtained concurrently to determine endogenous creatinine clearance (CL), total (TE) and fractional excretion (FE) of electrolytes (Na, K, Cl, P), electrolyte CL, urine and serum osmolality, urine enzyme activities (gamma-glutamyltransferase and N-acetyl-beta-D-glucosaminidase), and urine protein concentration. Urine production was quantified. Three months later, 10 of the 12 llamas were fed a grass hay diet and water ad libitum. Similar samples were obtained, and similar measurements were made. Urine production was higher when the llamas were fed the mixed hay diet. Total urine volume for llamas fed mixed hay ranged from 628 to 1,760 ml/24 h, with a median of 1,307.5 ml/24h, compared with a range of 620 to 1,380 ml/24 h and a median of 927.50 ml/24h for llamas fed grass hay. Median urine osmolality was higher in llamas fed mixed hay (1,906 mOsm/kg of body weight, with a range of 1,237 to 2,529 mOsm/kg), compared with llamas fed grass hay (1,666 mOsm/kg with a range of 1,163 to 2,044 mOsm/kg). Creatinine CL did not vary significantly over time for either diet.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hodgkin''s disease-like lymphoproliferative disorders in patients with different underlying immunodeficiency states

An actuarial life-table approach was used to study the mortality of 277 calves born alive in 16 traditionally managed herds in Bauchi, Nigeria from 1993 to 1995. The proportion of calves in the herds surviving for the first 12 months was 53.8%. The probability of dying was greatest during the first month of life and decreased with age. The proportion of calves surviving in the herds has been increasing for the last 2 years. We suspect that this is probably due to improvements in management practices. Septicaemia, malnutrition and injury were the common causes of calf mortality. We recommend that more attention be given to improving the management of calves early in life in order to reduce mortality of calves and hence reduce economic losses to the herd owner.