Large Increase In Volume Research Articles

Impact of South Africa's Monetary Policy on the LNS Economies

The countries in the Common Monetary Area (CMA), South Africa, Lesotho, Namibia and Swaziland, have harmonised their monetary and exchange rate policies in a quasi-monetary union since 1990. Lesotho, Namibia and Swaziland (LNS) have pegged their currencies to the South African Rand thus effectively surrendering monetary policy to the South African reserve bank. The arrangement has resulted in benefits in the form of lower prices, economy on trading costs, and a large increase in trade volume and cross-border financial transactions. However, one cost that has confronted the LNS economies in this monetary arrangement is the loss of independent monetary policy decision-making for stabilisation purposes. This study applies VAR to trace the impact of South Africa Reserve Bank°Os (SARB) monetary policy on the LNS economies. Specifically, the study examines how a change in the policy instrument of the Reserve Bank of South Africa affects money, credit and level of prices in the LNS economies and consequently assesses the capability of these economies to undertake independent monetary policy. Both the impulse response functions and the cumulated forecast errors show that the lending rates, level of prices and money supply respond instantaneously to changes in the repo rate by the South African reserve bank. Our analysis confirms that the South African repo rate is the relevant policy instrument

Breathing strategy to preserve exercising cardiac function in patients with heart failure

The heart and lungs are closely linked as they lie in series, share a common surface area and compete for space within the thoracic cavity. The heart and lungs are exposed to the similar changes in intrathoracic pressure, and reflexes within one organ can influence the other (i.e. vagal influence of lung inflation on heart rate). In patients with heart failure, these cardiopulmonary interactions may be altered due to decreased lung and left ventricular compliance, increased cardiac size, high cardiac filling pressure and altered receptor sensitivity to neural activation. Exercise further affects the cardiopulmonary interactions by stimulating an increase in the depth and frequency of breathing which accentuates the fluctuations in intrathoracic pressure, and by requiring large increases in stroke volume and heart rate in order to respond to the increased metabolic demand. Previous work from our laboratory suggested that patients with heart failure avoid high lung volumes during exercise, often at the expense of unnecessary large positive expiratory intrathoracic pressures resulting in significant wasted effort. Moreover, we also observed that voluntarily increases in lung volume in patients with heart failure induced a mild relative bradycardia, a response not observed in similar aged healthy individuals. Thus, we hypothesized that the rapid shallow low lung volume breathing, in combination with positive expiratory intrathoracic pressure, often adopted by patients with heart failure during exercise is an attempt to preserve, or even enhance, the cardiac response to exercise.

Evolution of pressure-amorphized zirconium tungstate upon annealing

Zirconium tungstate Zr(WO 4) 2 exhibits irreversible amorphization at high pressure. Upon heating, the pressure-amorphized phase transforms into different phase/phases depending on the pressure applied during heating. Transformation of pressure-amorphized samples to metastable cubic phase during isochronal annealing at ambient pressure is investigated using X-ray diffraction and Raman spectroscopy. Though the X-ray diffraction and Raman spectra show only monotonic changes up to 850 K in the amorphous state, the sample exhibits dramatic changes in the color from gray to black to white. The relaxation of the amorphous phase during annealing suggests gradual irreversible volume increase by about 6%, whereas the tungstate tetrahedra are found to shrink. Crystallization to cubic phase at 900 K is accompanied by a large increase in the sample volume. The specific volumes of the amorphous phases obtained from cycling the samples to different pressures suggest the possibility of polyamorphism in this system.

Diet Optimization Methods Can Help Translate Dietary Guidelines into a Cancer Prevention Food Plan ,

Mathematical diet optimization models are used to create food plans that best resemble current eating habits while meeting prespecified nutrition and cost constraints. This study used linear programming to generate food plans meeting the key 2007 dietary recommendations issued by the World Cancer Research Fund/American Institute of Cancer Research (WCRF/AICR). The models were constructed to minimize deviations in food intake between the observed and the WCRF/AICR-recommended diets. Consumption constraints were imposed to prevent food plans from including unreasonable amounts of food from a single group. Consumption norms for nutrients and food groups were taken from dietary intake data for a sample of adult men and women (n = 161) in the Pacific Northwest. Food plans meeting the WCRF/AICR dietary guidelines numbers 3–5 and 7 were lower in refined grains and higher in vegetables and fruits than the existing diets. For this group, achieving cancer prevention goals required little modification of existing diets and had minimal impact on diet quality and cost. By contrast, the need to meet all nutritional needs through diet alone (guideline no. 8) required a large food volume increase and dramatic shifts from the observed food intake patterns. Putting dietary guidelines into practice may require the creation of detailed food plans that are sensitive to existing consumption patterns and food costs. Optimization models provide an elegant mathematical solution that can help determine whether sets of dietary guidelines are achievable by diverse U.S. population subgroups.

Endocrinologic Control of Normal Canine Ovarian Function

In dogs, the termination of the 3-10-month obligate anoestrus involves selection of a cohort of LH-sensitive follicles, presumably from a wave of dominant small antral follicles that would otherwise undergo atresia. The number and size of such follicles appears to increase, especially during the last 50 days of anoestrus when the already elevated concentrations of FSH become further elevated. The final selection and eventual terminal development of these follicles is caused by an increased frequency of high-amplitude LH pulses at the end of anoestrus. Concomitant increases in FSH are typically small or negligible. High concentrations of FSH in anoestrus are likely to be important in maintaining, if not stimulating, overlapping waves of dominant follicles throughout anoestrus, their expression of aromatase activity and basal oestradiol secretion sufficient to suppress LH by negative feedback. An attractive hypothesis is that late anoestrus increases in LH-stimulate synthesis of precursor androgen for already available FSH-dependent aromatase. After 7 or more days of elevated LH, and perhaps 2-5 days of semi-autonomous growth, with maximal oestradiol production reached, follicle capacity to further increase oestradiol becomes limited and excess progesterone becomes increasingly secreted. The pre-ovulatory LH surge and oestrus onset are then triggered - often synchronously and in concert with the terminal maturation of the follicles - by central effects of the large decrease in the oestrogen to progestin ratio. Follicular endocrine and paracrine events during and following the LH surge are likely similar to those reported for other species. The prolonged luteal phase lengths of 55-75 days in non-pregnant bitches bracket the 64 +/- 1 day in pregnancy and represent a genetically programmed luteal cell lifespan approximating gestation length as occurs in the luteal phase of hysterectomized animals of most polyoestrous artiodactyls and rodents. The 30-40-day slow regression after day 20 to 30 involves periodic cell death, diminution in cell size, low levels of apoptosis and minimal or modest involvement of endogenous prostaglandin F (PGF) production. The canine corpus luteum (CL) is dependent on both LH and prolactin as stimulating luteotrophins by day 15, and as required luteotrophins by days 20-25, if not earlier. Thereafter, both luteotrophins likely have cellular mechanisms of action similar to those reported for other species. Progesterone secretion during pregnancy is greatly enhanced by characteristic, and probably relaxin-stimulated, increases in prolactin concentration starting at or after day 25, and persisting to term. Near term, foetoplacental maturation results in the placental release of large, luteolytic amounts of PGF for 1-2 days pre-partum. Pre-partum luteolysis, like that induced by exogenous prostaglandin, likely involves a cascade enhanced by the removal of progesterone inhibition of PGF release and some degree of intra-luteal PGF synthesis. That a likely twofold or greater increase in progesterone production by the CL of pregnancy does not result in significantly higher serum progesterone than in non-pregnant metoestrus relates to several biological changes, including a large increase in plasma volume of distribution, increased metabolism of progesterone by increased uterine, placental and mammary masses and increased liver clearance and excretion of progesterone and progesterone metabolite. Anoestrus length and ovarian cycle intervals, variable within and among bitches, are likely affected by neuroendocrine components of an endogenous circannual cycle, albeit only photo-entrained in the Basenji breed. This may be modified by the prior luteal phase, exposure to oestrus female pheromones and as yet unknown mechanisms that likely operate via inhibitory opioidergic and/or stimulatory dopaminergic hypothalamic pathways affecting late anoestrus increases in LH.

EMAAS: An extensible grid-based Rich Internet Application for microarray data analysis and management

BackgroundMicroarray experimentation requires the application of complex analysis methods as well as the use of non-trivial computer technologies to manage the resultant large data sets. This, together with the proliferation of tools and techniques for microarray data analysis, makes it very challenging for a laboratory scientist to keep up-to-date with the latest developments in this field. Our aim was to develop a distributed e-support system for microarray data analysis and management.ResultsEMAAS (Extensible MicroArray Analysis System) is a multi-user rich internet application (RIA) providing simple, robust access to up-to-date resources for microarray data storage and analysis, combined with integrated tools to optimise real time user support and training. The system leverages the power of distributed computing to perform microarray analyses, and provides seamless access to resources located at various remote facilities. The EMAAS framework allows users to import microarray data from several sources to an underlying database, to pre-process, quality assess and analyse the data, to perform functional analyses, and to track data analysis steps, all through a single easy to use web portal. This interface offers distance support to users both in the form of video tutorials and via live screen feeds using the web conferencing tool EVO. A number of analysis packages, including R-Bioconductor and Affymetrix Power Tools have been integrated on the server side and are available programmatically through the Postgres-PLR library or on grid compute clusters. Integrated distributed resources include the functional annotation tool DAVID, GeneCards and the microarray data repositories GEO, CELSIUS and MiMiR. EMAAS currently supports analysis of Affymetrix 3' and Exon expression arrays, and the system is extensible to cater for other microarray and transcriptomic platforms.ConclusionEMAAS enables users to track and perform microarray data management and analysis tasks through a single easy-to-use web application. The system architecture is flexible and scalable to allow new array types, analysis algorithms and tools to be added with relative ease and to cope with large increases in data volume.

Quantification of astrocyte volume changes during ischemia in situ reveals two populations of astrocytes in the cortex of GFAP/EGFP mice

Energy depletion during ischemia leads to disturbed ionic homeostasis and accumulation of neuroactive substances in the extracellular space, subsequently leading to volume changes in astrocytes. Confocal microscopy combined with 3D reconstruction was used to quantify ischemia-induced astrocyte volume changes in cortical slices of GFAP/EGFP transgenic mice. Twenty-minutes of oxygen-glucose deprivation (OGD) or oxygen-glucose deprivation combined with acidification (OGD(pH 6.8)) revealed the presence of two distinct astrocytic populations, the first showing a large volume increase (HR astrocytes) and the second displaying a small volume increase (LR astrocytes). In addition, changes in resting membrane potential (V(m)), measured by the patch-clamp technique, supported the existence of two astrocytic populations responding differently to ischemia. Although one group markedly depolarized during OGD or OGD(pH 6.8), only small changes in V(m) toward more negative values were observed in the second group. Conversely, acidification (ACF(pH 6.8)) led to a uniform volume decrease in all astrocytes, accompanied by only a small depolarization. Interestingly, two differently responding populations were not detected during acidification. Differences in the expression of inwardly rectifying potassium channels (Kir4.1), glial fibrillary acidic protein (GFAP), and taurine levels in cortical astrocytes were detected using immunohistochemical methods. We conclude that two distinct populations of astrocytes are present in the cortex of GFAP/EGFP mice, based on volume and V(m) changes during exposure to OGD or OGD(pH 6.8). Immunohistochemical analysis suggests that the diverse expression of Kir4.1 channels and GFAP as well as differences in the accumulation of taurine might contribute to the distinct ability of astrocytes to regulate their volume.

Sources of Variability in Reflectance Measurements on Normal Cadaver Ears

The development of acoustic reflectance measurements may lead to noninvasive tests that provide information currently unavailable from standard audiometric testing. One factor limiting the development of these tests is that normal-hearing human ears show substantial intersubject variations. This work examines intersubject variability that results from measurement location within the ear canal, estimates of ear-canal area, and variations in middle-ear cavity volume. Energy reflectance (ER) measurements were made on nine human-cadaver ears to study three variables. (1) ER was measured at multiple ear-canal locations. (2) The ear-canal area at each measurement location was measured and the ER was calculated with the measured area, a constant area, and an acoustically estimated area. (3) The ER was measured with the middle-ear cavity in three conditions: (1) normal, (2) the mastoid widely opened (large air space), and (3) the mastoid closed off at the aditus ad antrum (small air space). Measurement-location effects are generally largest at frequencies below about 2000 Hz, where in some ears reflectance magnitudes tend to decrease systematically as the measurement location moves away from the tympanic membrane but in other ears the effects seem minimal. Intrasubject variations in reflectance due to changes in either measurement location within the ear canal or differences in the estimate of the ear-canal area are smaller than variations produced by large variations in middle-ear cavity air volume or intersubject differences. At frequencies below 2000 Hz, large increases in cavity volume systematically reduce the ER, with more variable changes above 2000 Hz. ER measurements depend on all variables studied: measurement location, ear-canal cross-sectional area, and middle-ear cavity volume. Variations within an individual ear in either measurement location or ear-canal cross-sectional area result in relatively small effects on the ER, supporting the notion that diagnostic tests (1) need not control for measurement location and (2) can assume a constant ear-canal area across most subjects. Variations in cavity volume produce much larger effects in ER than measurement location or ear-canal area, possibly explaining some of the intersubject variation in ER reported among normal ears.

PEGylation of Human Serum Albumin: Reaction of PEG-Phenyl-Isothiocyanate with Protein

Successful and cost-effective PEGylation protocols require pure functionalized PEG reagents, which can be synthesized by simple and efficient procedures, exhibit high stability against hydrolysis, and maintain a level of reactivity with protein functional groups under mild reaction conditions. PEG-phenyl-isothiocyanate (PIT-PEG) is a new functionalized PEG having these characteristics, and has been synthesized by condensation of the bifunctional reagent 4-isothiocyanato phenyl isocyanate with monomethoxy PEG (mPEG). The data of (1)H NMR and colormetric analysis of the new PEG reagent establish that the mPEG has been quantitatively functionalized. The t 1/4 values for the hydrolysis of PIT-PEG5K in 100 mM phosphate solution at pH 6.5 and 9.2 are about 95 and 40 h, respectively. Incubation of human serum albumin (HSA, 0.5 mM) with a 10-fold molar excess of PIT-PEG (3K or 5K) at pH 6.5 and 9.2 generated PEG-HSA conjugates with average of 3.5 and 6.0 PEG chains per HSA molecule, respectively. The circular dichroism spectra of the conjugates showed that PEGylation of HSA has little influence on the secondary structure of HSA. The hexaPEGylated HSA, (TCP-PEG5K) 6-HSA, exhibited very high hydrodynamic volume, and the molecular radius of HSA increased from 3.95 to 6.57 nm on hexaPEGylation. The hexaPEGylation also increased the viscosity of 4% HSA from 1.05 to 2.10 cP, and the colloid osmotic pressure from 15.2 to 48.0 mmHg. The large increase in the hydrodynamic volume and the solution properties of (TCP-PEG5K) 6-HSA suggest that it could be a potential candidate as a plasma volume expander. PIT-PEG is a useful addition to the spectrum of functionalized PEG reagents available for surface decoration of proteins with PEG.

SU-GG-T-22: Dosimetric Analysis of Real Time and Post Implantation Dosimetry for Prostate

Purpose: To quantify the changes in prostate volume and its effect on dosimetry for real time inverse planned low dose rate brachytherapy.Method and Materials:Ultrasoundimages of 30 consecutive patients in the lithotomy position were obtained one week before the implant procedure. The prostate and the urethra were contoured and then an optimized treatment plan was developed in order to obtain the number of Palladium‐103 seeds needed to deliver the prescribed dose of 120Gy to the target. At the day of the implant a new optimized plan was created based on the patient's current prostate volume. Linked seeds were implanted according to the latter plan. A CT scan was performed after the seeds were implanted and the prostate and urethra were contoured. The post‐implant treatment plan was developed by locating the seeds on the CTimages and calculating the dose distribution. Results: By comparing the real time in the operating room and the post implant prostate volumes, it was found that there was an increase in volume ranging from 31% to 39%. According to the post implant plans the V100 ranged from 81% to 99%. A larger volume increase was observed for smaller size prostates. Furthermore, the smaller prostate volumes showed the lower values of V100. Conclusion: Prostate volume changes due to swelling after the implant appears to be associated with reduction of dose coverage as reflected in post implant dosimetry. Artifacts generated by the seeds, compromised the resolution of the CTimages and hence the accuracy of post implant prostate volumes. It appears that these factors effecttreatment planning which can ultimately determine the success in treating the cancer.

Traffic Speeds on Interstates and Freeways 10 Years After Repeal of National Maximum Speed Limit

Objectives. Essentially all published analyses of operational and safety outcomes related to enactment or repeal of the national maximum speed limit (NMSL) were based on data limited to the initial 1–3 years. The purpose of the present study was to collect and analyze longer term speed data. Method. In 2006, traffic speeds were surveyed at 26 locations on urban and rural expressways in five states (California, Montana, Nevada, New Mexico, and Texas) where speeds had been measured in 1996, immediately after repeal of NMSL. Most speed limits were unchanged during the approximately 10-year period. However, Montana introduced a numeric 75 mph limit for passenger vehicles in place of a “reasonable and prudent” limit. In Texas, urban freeway speed limits for passenger vehicles were reduced 5 mph, and truck limits were increased 5 mph. Results. On rural interstates without speed limit changes, travel speeds increased for both passenger vehicles and large trucks; the proportion of passenger vehicles exceeding 80 mph tripled. On rural interstates in Montana where speed limits were lowered for passenger vehicles, travel speeds decreased, even for large trucks whose speed limits had not changed. On urban freeways where speed limits did not change, travel speeds declined somewhat for both passenger vehicles and large trucks; during the study period there also were large increases in traffic volume and development of surrounding areas. On urban freeways in Texas where speed limits declined for passenger vehicles, travel speeds generally decreased, even for large trucks whose speed limits actually had increased. Conclusions. The data suggest that where traffic volumes allow, travel speeds still are increasing 10 years after repeal of NMSL, and many drivers are speeding. The study also shows that speed increases can be curbed and even reversed when speed limits are lowered. Increased enforcement is needed to curb speed increases and the increased risk of serious crashes.

Trading time and trading activity: evidence from extensions of the NYSE trading day

The New York Stock Exchange extended its trading hours by 30 min in 1974 and in 1985; the first extension resulting in a delayed close and the second in an early open. We find a shift in volume to the new period after each extension. Additionally, there is a larger increase in volume after the 1985 extension than after the 1974 extension. We argue that the second effect is explained by the first. The extension at the end of the day allows some investors to postpone their trades, which results in occasional information cancellation or discovery; this mutes the effect of the extension on volume. In contrast, the extension at the start of the day allows some investors to accelerate trades, which precludes information cancellation or discovery and its negative effect on volume. This explanation suggests that the effect of an extension on volume depends, at least in part, on its timing.

M1/M3 and M2/M4 muscarinic receptor double-knockout mice present distinct respiratory phenotypes

We investigated the role of muscarinic acetylcholine receptors in the control of breathing. Baseline breathing at rest and ventilatory responses to brief exposures to hypoxia (10% O(2)) and hypercapnia (3% and 5% CO(2)), measured by whole-body plethysmography in partially restrained animals, were compared in mice lacking either M(1) and M(3) or M(2) and M(4) muscarinic receptors, and in wild-type matched controls. M(1/3)R double-knockout mice showed at rest an elevated ventilation (V (E)) due to a large (57%) increase in tidal volume (V(T)). Chemosensory ventilatory responses were unaltered. M(2/4)R double-knockout mice were agitated and showed elevated V (E) and breathing frequency (f(R)) at rest when partially restrained, but unaltered V (E) and low f(R) when recorded unrestrained. Chemosensory ventilatory responses were unaltered. The results suggest that M(1) and M(3) receptors are involved in the control of tidal volume, while M(2) and M(4) receptors may be involved in the control of breathing frequency at rest and response to stress.

Amyloid Protofibril is Highly Voluminous and Compressible

We report here results of the first direct measurement of partial volume and compressibility changes of a protein as it forms an amyloid protofibril. We use a high precision density meter and an ultrasonic velocity meter on a solution of intrinsically denatured, disulfide-deficient variant of hen lysozyme, and follow the time-dependent changes in volume and compressibility, as the protein spontaneously forms a protofibril. We have found a large increase in partial specific volume with time from 0.684 to 0.724 mL x g-1 (Deltanu = 0.040 mL x g-1 corresponding to 570 mL x (mol monomer)-1) and in partial specific adiabatic compressibility coefficient from -7.48 x 10(-12) to +1.35 x 10(-12) cm2 x dyn-1 (Deltabetas = 8.83 x 10(-12) x cm2 x dyn-1) as the monomer transforms into a protofibril. The results demonstrate that the protofibril is a highly voluminous and compressible entity, disclosing a cavity-rich, fluctuating nature for the amyloid protofibril. The volume and compressibility changes occur in two phases, the faster one preceding the major development of the beta-structure in the protofibril as monitored by CD.

Observed bubble dynamics in oxygen or heliox breathing and altitude decompression sickness

altitude decompression sickness (DCS) is a common risk in aviation and has been extensively studied over the past two decades ([2][1], [3][2], [9][3]). Attempts have been made to find a correlation between ultrasonic bubble detection and symptoms of altitude DCS ([1][4], [8][5]). Models

Changes in the Pelvic Anatomy After an IMRT Treatment Fraction of Prostate Cancer

To quantify the three-dimensional variations of pelvic anatomy after a single treatment fraction. Forty-six prostate cancer patients underwent computed tomography (CT) scanning with an in-room CT-on-rail system, before and immediately after one intensity-modulated radiotherapy (IMRT) session. To study the soft-tissue anatomy changes, the pre- and post-treatment CT images were registered using the bony structure with an in-house image registration software system. The center of volume for both the prostate and seminal vesicles was used to assess the relative displacement of the same structure after the treatment fraction. During one treatment fraction (21 +/- 4 min), both the prostate and seminal vesicles showed statistically significant systematic trends in the superior and anterior directions of the patient's anatomy. The net increase in bladder volume was huge (127 +/- 79 cm(3)), yet this change did not translate into large target displacements. Although the population mean displacements in either direction were 1.3 +/- 2.9 mm for the prostate and 1.2 +/- 4.1 mm for the seminal vesicles in the anterior direction, a few patients had displacements as large as 8.4 mm and 15.6 mm, respectively. These large displacements correlated strongly (p < 0.001) with large rectal volume increases caused by gaseous build-up in the rectum. The observed intrafraction variations in anatomy during prostate IMRT sessions suggest that, for any given fraction, the organ motion and volume changes can potentially lead to compromised target coverage in about 15% of patients in whom the prostate position shifted >4 mm.

Tribute to P. L. Lutz: a message from the heart – why hypoxic bradycardia in fishes?

The sensing and processing of hypoxic signals, the responses to these signals and the modulation of these responses by other physical and physiological factors are an immense topic filled with numerous novel and exciting discoveries. Nestled among these discoveries, and in contrast to mammals, is the unusual cardiac response of many fish to environmental hypoxia - a reflex slowing of heart rate. The afferent and efferent arms of this reflex have been characterised, but the benefits of the hypoxic bradycardia remain enigmatic since equivocal results have emerged from experiments examining the benefit to oxygen transfer across the gills. The main thesis developed here is that hypoxic bradycardia could afford a number of direct benefits to the fish heart, largely because the oxygen supply to the spongy myocardium is precarious (i.e. it is determined primarily by the partial pressure of oxygen in venous blood, Pv(O(2))) and, secondarily, because the fish heart has an unusual ability to produce large increases in cardiac stroke volume (V(SH)) that allow cardiac output to be maintained during hypoxic bradycardia. Among the putative benefits of hypoxic bradycardia is an increase in the diastolic residence time of blood in the lumen of the heart, which offers an advantage of increased time for diffusion, and improved cardiac contractility through the negative force-frequency effect. The increase in V(SH) will stretch the cardiac chambers, potentially reducing the diffusion distance for oxygen. Hypoxic bradycardia could also reduce cardiac oxygen demand by reducing cardiac dP/dt and cardiac power output, something that could be masked at cold temperature because of a reduced myocardial work load. While the presence of a coronary circulation in certain fishes decreases the reliance of the heart on Pv(O(2)), hypoxic bradycardia could still benefit oxygen delivery via an extended diastolic period during which peak coronary blood flow occurs. The notable absence of hypoxic bradycardia among fishes that breathe air during aquatic hypoxia and thereby raise their Pv(O(2)), opens the possibility that that the evolutionary loss of hypoxic bradycardia may have coincided with some forms of air breathing in fishes. Experiments are needed to test some of these possibilities. Ultimately, any potential benefit of hypoxic bradycardia must be placed in the proper context of myocardial oxygen supply and demand, and must consider the ability of the fish heart to support its routine cardiac power output through glycolysis.

Accelerated carbonation of reactive MgO cements

Experiments were carried out to determine the conditions for the accelerated carbonation of reactive MgO cements, which are blends of MgO, Portland cement (PC) and pulverised fuel ash (pfa). The samples were exposed to two levels of CO2 (5 and 20%) in their curing environment at two levels of relative humidity (RH), namely 65 and 98%, RH, and the resulting changes in stiffness and toughness were contrasted with reference samples, which were cured in 98% RH and ambient CO2 levels. Carbonation of MgO, following its hydration into brucite, yields nesquehonite, whereas that of Portland cement resulted in calcite. The conversion of brucite into nesquehonite increased the strength and toughness of the blends without PC, and this was attributed to the large increase in solid volume due to the carbonation reactions. The accelerated carbonation treatment damaged the blends without MgO, although it did not alter significantly the dynamic stiffness and toughness of the blends containing equal quantities of MgO and PC. Contrary to PC-based cements, in which the highest carbonation rates are found for intermediate humidity levels, the accelerated carbonation of MgO cements requires high levels of humidity and this is attributed to the high water consumption of the carbonation reaction of brucite, whereas carbonation of the PC liberates water

Hypotonic swelling of salicylate-treated cochlear outer hair cells

The outer hair cell (OHC) is a hydrostat with a low hydraulic conductivity of P f = 3 × 10 −4 cm/s across the plasma membrane (PM) and subsurface cisterna that make up the OHC’s lateral wall. The SSC is structurally and functionally a transport barrier in normal cells that is known to be disrupted by salicylate. The effect of sodium salicylate on P f is determined from osmotic experiments in which isolated, control and salicylate-treated OHCs were exposed to hypotonic solutions in a constant flow chamber. The value of P f = 3.5 ± 0.5 × 10 −4 cm/s (mean ± s.e.m., n = 34) for salicylate-treated OHCs was not significantly different from P f = 2.4 ± 0.3 × 10 −4 cm/s (mean ± s.e.m., n = 31) for untreated OHCs ( p = .3302). Thus P f is determined by the PM and is unaffected by salicylate treatment. The ratio of longitudinal strain to radial strain ε z / ε c = −0.76 for salicylate-treated OHCs was significantly smaller ( p = .0143) from −0.72 for untreated OHCs, and is also independent of the magnitude of the applied osmotic challenge. Salicylate-treated OHCs took longer to attain a steady-state volume which is larger than that for untreated OHCs and increased in volume by 8–15% prior to hypotonic perfusion unlike sodium α-ketoglutarate-treated OHCs. It is suggested that depolymerization of cytoskeletal proteins and/or glycogen may be responsible for the large volume increase in salicylate-treated OHCs as well as the different responses to different modes of application of the hypotonic solution.

Electrification and Lightning in an Idealized Boundary-Crossing Supercell Simulation of 2 June 1995*

AbstractA nonhydrostatic cloud model with electrification and lightning processes was utilized to investigate how simulated supercell thunderstorms respond when they move into environments favorable for storm intensification. One model simulation was initialized with an idealized horizontally varying environment, characteristic of that observed across an outflow boundary in the west Texas Panhandle on 2 June 1995 with larger convective available potential energy (CAPE) and wind shear on the boundary’s cool side. That simulation was compared with a control simulation initialized without the boundary. The simulated right-moving supercell rapidly increased in updraft strength and volume, low-level rotation, radar reflectivity, and 40-dBZ echo-top height as it crossed the boundary, whereas the supercell that did not cross the boundary failed to intensify. For the same kinematic and microphysical evolution and the same inductive charging parameterization, four noninductive (NI) charging parameterizations were tested. In all four cases, there was a general tendency for the charge regions to be lofted higher within the updraft after crossing the boundary. Once the precipitation regions between the main storm and a secondary storm started merging farther on the cool side of the boundary, a gradual deepening and strengthening of the lowest charge regions occurred with relatively large increases in hail and graupel volume, charging rates, charge volume, charge density, and intracloud and cloud-to-ground (CG) flash rates. The negative charge present on graupel within the downdraft appeared to have a common origin via strong NI charging within the midlevel updraft in all four NI cases. Positive channels were more consistent in coming closer to the ground with time compared to negative channels within this graupel and hail-filled downdraft (four of four cases). Those NI schemes that also set up a positive dipole (three of four cases) or inverted tripole (two of four cases) above the downdraft had downward-propagating positive channels that reached ground as positive CG (+CG) flashes. The best overall performance relative to the 2 June 1995 CG lightning observations occurred within one of the rime-accretion-rate-based schemes and the Gardiner scheme as parameterized by Ziegler.