Academic literature on the topic 'Low G Man: The Low Gravity Man'

The low-Km activity of mannose-6-phosphatase (Man-6-Pase) has been used for many years to measure the structural integrity of microsomes. Recently histone II-A has been shown to activate glucose-6-phosphatase (Glc-6-Pase) and Man-6-Pase activities. However, in contrast to detergents, this compound appears to activate without disrupting microsomal vesicles (J.-F. St-Denis, B. Annabi, H. Khoury, and G. van de Werve. 1995. Biochem. J. 310: 221-224). This suggests that Man-6-Pase latency can be abolished without disrupting microsomal integrity and that even normally microsomes may manifest some low-Km Man-6-Pase activity without being "leaky." We have studied the relationship of Man-6-Pase with microsomal integrity further by measuring the latency of several enzymes reported to reside within the lumen of endoplasmic reticulum. We have also correlated this latency with the microsomal permeability of substrates for these enzymes. We found that (i) lumenal enzymes have different degrees of latency when compared with each other, (ii) permeability, as determined via osmotically induced changes in light scattering, is not always consistent with enzymatic latency, (iii) increases in the hydrolysis of Glc-6-P and Man-6-P were not parallel when microsomes were treated with low but increasing concentrations of detergent, and (iv) kinetic studies suggest that mannose-6-phosphate is hydrolyzed by untreated microsomes by more than a single mechanism. We propose that Man-6-Pase is not a reliable index of the integrity of microsomes.Key words: glucose-6-phosphatase, mannose-6-phosphatase, microsomes, rat liver, intactness.

1. Urea kinetics were measured using prime/intermittent oral doses of [15N15N]urea in six healthy men taking diets adequate in energy and containing either 74 or 30 g of protein/day. 2. On 74 g of protein/day, urea production (199 mg of N day−1 kg−1) was 121% of intake, with 60% of the urea produced being excreted in the urine and 40% being salvaged in the colon; 69% of the salvaged nitrogen was retained in the metabolic nitrogen pool. 3. Nitrogen balance was not maintained on 30 g of protein/day. There was a significant decrease in the urea production rate (123 mg of N day−1 kg−1) and 54% of production was excreted in urine, with 46% being salvaged. 4. The pattern of urea production and salvaging on 30 g of protein/day was different to that seen in an earlier study on 35 g of protein/day, with a significant decrease in both production (71%) and salvaging (50%). 5. These data reinforce the conclusions drawn from an earlier study, that the salvaging of urea nitrogen by the colon is an integral part of the process of adaptation to low protein diets. The salvage system appears to fail on an intake of 30 g of protein/day and nitrogen is no longer conserved in sufficient amounts for balance to be maintained. 6. The changes seen in urea kinetics reinforce the conclusion based upon nitrogen balance that the minimum physiological requirement for protein in normal adult man lies between 30 and 35 g of protein/day.

Asteroseismology provides global stellar parameters such as masses, radii, or surface gravities using mean global seismic parameters and effective temperature for thousands of low-mass stars (0.8 M⊙ < M < 3 M⊙). This methodology has been successfully applied to stars in which acoustic modes excited by turbulent convection are measured. Other methods such as the Flicker technique can also be used to determine stellar surface gravities, but only works for log g above 2.5 dex. In this work, we present a new metric called FliPer (Flicker in spectral power density, in opposition to the standard Flicker measurement which is computed in the time domain); it is able to extend the range for which reliable surface gravities can be obtained (0.1 < log g < 4.6 dex) without performing any seismic analysis for stars brighter than Kp < 14. FliPer takes into account the average variability of a star measured in the power density spectrum in a given range of frequencies. However, FliPer values calculated on several ranges of frequency are required to better characterize a star. Using a large set of asteroseismic targets it is possible to calibrate the behavior of surface gravity with FliPer through machine learning. This calibration made with a random forest regressor covers a wide range of surface gravities from main-sequence stars to subgiants and red giants, with very small uncertainties from 0.04 to 0.1 dex. FliPer values can be inserted in automatic global seismic pipelines to either give an estimation of the stellar surface gravity or to assess the quality of the seismic results by detecting any outliers in the obtained νmax values. FliPer also constrains the surface gravities of main-sequence dwarfs using only long-cadence data for which the Nyquist frequency is too low to measure the acoustic-mode properties.

1. The effect of total starvation for 4–5 days on the intestinal uptake and urinary excretion of markers from an orally administered mixture of mannitol (5 g), [14C]mannitol (0.5 μCi), lactulose (10 g) and 51Cr-labelled ethylenediaminetetra-acetate (51Cr-EDTA) (30 μCi), was assessed in five lean (group 1) and four obese (group 2) subjects. The effect of a very low calorie diet for 1 week and of a subsequent 5 day period of total starvation on intestinal permeability was assessed in a similar way in another group of obese subjects (group 3). Transit time from mouth to caecum of the fastest component of the oral mixture was assessed by the appearance of hydrogen in breath (all subjects), and the configuration of the transit spectrum through various segments of the gastrointestinal tract, was assessed by a radionuclide scan method (group 2 subjects only). The effect of starvation on plasma/renal clearance of these markers in subjects of group 2 was assessed with the use of a bolus intravenous injection of a mixture of mannitol (2 g), [14C]mannitol (10 μCi), lactulose (0.1 g) and 51Cr-EDTA (5 μCi). 2. The uptake and urinary excretion of orally administered mannitol was decreased by total starvation. The mean decrease was 47% in the lean subjects (P < 0.025), 33% in group 2 obese subjects (P < 0.05) and 41% in group 3 obese subjects P > 0.05). In contrast, starvation produced no significant change in either the excretion of 51Cr-EDTA or lactulose. 3. There was no significant effect of starvation on transit time, whether assessed by the increase in breath hydrogen concentration in expired air or by radionuclide scanning. 4. Starvation produced no significant change in the clearance of the intravenously administered markers from the plasma. Oxidation of intravenous mannitol was estimated to account for about 1% of the clearance both before and during starvation. 5. The data provide evidence of a selective decrease in the absorption and excretion of mannitol during short-term total starvation. The changes in the excretion of mannitol are not due to alterations in renal function or gastrointestinal transit time, or to changes in the oxidation and plasma clearance of mannitol. They are likely to reflect changes in the small intestinal mucosa during early starvation. In contrast, very low calorie diets taken for at least 1 week prevent changes in small intestinal permeability.

✓ The authors have studied the effect of a low-dose (0.28 gm/kg) bolus infusion of mannitol on brain water in man. In eight patients with severe head injury, small pieces of subcortical white matter were taken at craniotomy both before and after infusion of mannitol. The tissue specific gravity was measured using a graduated specific-gravity column, and from it the brain water content was calculated. White matter specific gravity rose from a mean (± standard error of the mean) of 1.0325 ± 0.0012 before mannitol infusion to 1.0352 ± 0.0011 after mannitol administration, and the brain water content fell from a mean of 80.94% ± 2.5% to 75.28% ± 2.3%. The differences were significant (p < 0.01). This study shows that, after head injury in man, mannitol increases the white matter specific gravity and probably does so by reducing brain water.

Recent advances in liver transplantation have caused a serious shortage of donor livers, and a consensus on determining brain death has not been reached by the medical community in several countries, including Japan. To overcome these circumstances, hepatocellular transplantation (HCTX) has been attempted because HCTX requires no vascular anastomosis and donor hepatocytes are easy to obtain from living donors, and easy to preserve for a long time. In many experimental studies on HCTX some promising findings have been obtained, but clinically there has been little progress. Our success with survival of autotransplanted monkey hepatocytes and the development of a preparation of human hepatocytes has renewed interest in clinical HCTX. A multipuncture perfusion method or collagenase perfusion via the umbilical vein enables us to obtain approximately 1 × 108 hepatocytes from partially resected liver (60 g). The clinical trial of HCTX into the spleen was performed in 10 patients in Japan. A CT image, taken 1 mo after HCTX, showed a low density area corresponding to the inoculated site, which suggested that the transplanted hepatocytes survived and possessed hepatocellular function. One patient who sustained hepatic encephalopathy and massive ascites has now returned to work 11 mo after HCTX and hepatic artery ligation. However, there were no definite findings for functional support of damaged livers by HCTX in the spleen. We will review our experiments on HCTX, and describe the current and future aspects of HCTX.

The metabolic response to a 150 or 400 g 13C-labelled pasta meal was studied for 8 h following rest or exercise at low or moderate workload (n 6). Following rest, the 400 g meal totally suppressed fat oxidation (v. 14.1 g following the 150 g meal) and a small amount of glucose was converted into fat (4.6 g), but fat oxidation remained high in subjects who had exercised following both the small (21.8 and 34.1 g) and large meal (14.1 and 32.3 g). Exogenous glucose oxidation was significantly higher in subjects who had remained at rest both following the small (67.6 g v. 60.4 and 51.3 g in subjects who exercised at low and moderate workloads) and large meal (152.2 v. 123.0 and 127.2 g). Endogenous glucose oxidation was similar in the three groups following the 150 g meal (42.3–58.0 g), but was significantly lower following the 400 g meal in subjects who had exercised at low workload (24.2 v. 72.2 g following rest; P<0.05), and was totally suppressed in those who had exercised at moderate workload. As a consequence, a larger positive glycogen balance was observed in subjects who exercised before the large meal (182.8–205.1 g v. 92.4 g following rest; P<0.05). Total fat oxidation calculated from 08.00 hours to 20.00 hours was similar in subjects who exercised at low and moderate workloads. These results indicate that: (1) de novo lipogenesis, which plays only a minor role for the disposal of an acute dietary carbohydrate load, is totally suppressed following exercise, even when a very large carbohydrate load is ingested; (2) the reduction in glycogen turnover as well as a preferential conversion of glucose into glycogen are responsible for the increase in glycogen stores following exercise; (3) for a similar energy expenditure, exercise at low workload for a longer period does not favour fat oxidation when the post-exercise period is taken into account.

1. Urea kinetics were measured by using prime/intermittent oral doses of [15N15N]urea in five healthy men taking formula diets adequate in energy and containing either 70 or 35 g of protein/day. In some studies the low-protein diet was supplemented with non-starch polysaccharides in the form of ispaghula husk or ripe bananas. 2. On the 70 g of protein/day diet urea production was 132% of intake. Only 54% of the urea produced was excreted in the urine with 46% being salvaged in the colon; 90% of the salvaged nitrogen was retained in the metabolic nitrogen pool. 3. On the 35 g of protein/day diet the small decrease in urea production rate compared with that on the 70 g of protein/day diet was not significant, but only 36% of the urea produced was excreted in urine, with the majority, 64%, being salvaged. 4. The extent of urea-nitrogen salvaging on the 35 g of protein/day diet was similar in magnitude to the decrease in nitrogen intake, with the effect that the sum of intake and salvaged nitrogen did not differ between the 35 and the 70 g of protein/day diets. This implies that quantitative control is exerted over the rate at which urea nitrogen is salvaged. 5. The addition of non-starch polysaccharides to the 35 g of protein/day diet had a demonstrable effect upon faecal weight and composition, but did not exert any significant influence upon urea kinetics. 6. It is concluded that large changes in the rate of urea production are not necessary for adaptation to a low-protein diet, rather the salvaging of urea nitrogen in the lower bowel appears to be an important mechanism through which the body adapts to a low-protein diet. The salvaging of urea nitrogen by the colon makes an important contribution to the conservation of body nitrogen.

ABSTRACT HD 4539 (alias PG 0044 + 097 or EPIC 220641886) is a bright (V = 10.2) long-period V1093 Her-type subdwarf B (sdB) pulsating star that was observed by the Kepler spacecraft in its secondary (K2) mission. We use the K2 light curve (78.7 d) to extract 169 pulsation frequencies, 124 with a robust detection. Most of these frequencies are found in the low-frequency region typical of gravity (g-)modes, but some higher frequencies corresponding to pressure (p-)modes are also detected. Therefore HD 4539 is a hybrid pulsator and both the deep and surface layers of the star can potentially be probed through asteroseismology. The lack of any frequency splitting in its amplitude spectrum suggests that HD 4539 has a rotation period longer than the K2 run and/or that it is seen pole-on. From asymptotic period spacing we see many high-degree modes, up to l = 12, in the spectrum of HD 4539, with amplitudes as low as a few ppm. A large fraction of these modes can be identified and for ∼29 per cent of them we obtain a unique and robust identification corresponding to l ≤ 8. Our study includes also a new determination of the atmospheric parameters of the star. From low-resolution spectroscopy we obtain Teff = 22 800 ± 160 K, log g = 5.20 ± 0.02, and log(N(He)/N(H)) = −2.34 ± 0.05. By fitting the SED we obtain Teff = 23 470$^{+650}_{-210}$ K, R⋆ = 0.26 ± 0.01 R⊙, and M⋆ = 0.40 ± 0.08 M⊙. Moreover, from 11 high-resolution spectra we see the radial velocity variations caused by the stellar pulsations, with amplitudes of ≈150 m s−1 for the main modes, and we can exclude the presence of a companion with a minimum mass higher than a few Jupiter masses for orbital periods below ∼300 d.

Glucocorticoids increase neutrophil counts by decreasing the margination of neutrophils and mobilizing neutrophils from the bone marrow pool. The mechanisms for these effects however are not fully elucidated, but it has been demonstrated that dexamethasone enhances release of colony stimulating factor (G-CSF) in-vitro. We therefore hypothesized, that dexamethasone may increase plasma levels of G-CSF. A double blind, randomized, placebo-controlled, three-way cross-over trial was conducted in nine healthy men. Every subject received four identical infusions of saline, 0.04 mg/kg or 1.0 mg/kg dexamethasone during three observation periods of 48 hours each. The low dose of dexamethasone increased G-CSF levels from a baseline of 15.5 ng/L (CI: 10.6–20.4) by 240% (CI: 115–366%) at 24 hours. The high dexamethasone dose increased G-CSF levels from a baseline of 12.3 ng/L (CI: 9.7–14.9) by 871% (CI: 592–1149%) at 24 hours (P = 0.008 for all comparisons). No further increase was observed at 48 hours but the effect was less pronounced (P &lt; 0.008 and P = 0.08 for the high and the low dose of dexamethasone, respectively). Granulocyte-macrophage-CSF (GM-CSF) levels were below the assay’s detection limit of 0.36 ng/L in all subjects. In conclusion, dexamethasone dose dependently increases G-CSF levels in healthy men, an effect which may account for some of its effects on neutrophils.

Les Maladies Inflammatoires Chroniques de l’Intestin (MICI) regroupent la maladie de Crohn (MC) et la Rectocolite Hémorragique (RCH), deux maladies qui se caractérisent par l’inflammation de la paroi d’une partie du tube digestif, source de lésions destructrices (ulcérations). Ces pathologies complexes sont influencées par de multiples facteurs génétiques et environnementaux. D’une part, de nombreux gènes de susceptibilité pour ces maladies ont été identifiés, mais ils ne permettent d’expliquer qu’une fraction mineure du développement des MICI. D’autre part, certaines études montrent qu’un dysfonctionnement du processus de prise en charge des xénobiotiques dans la muqueuse digestive peut jouer un rôle dans l’initiation et/ou la progression des MICI. Notre travail a consisté, dans un premier temps, en l’étude du profil d’expression de gènes codant pour des protéines impliquées dans le métabolisme et le transport des xénobiotiques. Une stratégie de RT-PCR quantitative en temps réel, permettant l’analyse simultanée de l’expression de 377 gènes, a été utilisée. Cette analyse a été réalisée sur des échantillons de muqueuse intestinale de sujets témoins et de patients atteints de MC, ainsi que sur cinq lignées de cellules épithéliales intestinales.Cette étude a permis d’identifier les systèmes de prise en charge des xénobiotiques présents dans la muqueuse intestinale saine. Des profils d’expression différents ont été mis en évidence entre les tissus intestinaux sains et inflammatoires, mais également entre les tissus intestinaux et les lignées cellulaires intestinales, ce qui suggère des différences majeures dans les processus de prise en charge cellulaire des xénobiotiques, et, par conséquent des différences de susceptibilité à l’effet des composés toxiques exogènes. Dans un second temps, la petite protéine G, Rac1, a été étudiée. Cette protéine est impliquée dans la réparation des ulcérations de l’épithélium intestinal et a récemment été identifiée comme la cible des métabolites actifs des médicaments thiopuriniques, largement prescrits dans le traitement des MICI. La nature et l’étendue de la variabilité de la séquence nucléotidique du gène Rac1 a été évaluée, chez des volontaires sains et des patients atteints de MICI, à l’aide d’une stratégie basée sur le couplage de l’analyse du polymorphisme de conformation de fragments d’ADN simple brin générés par réaction de polymérisation en chaine (PCR-SSCP) et du séquençage. Des études in silico et in vitro des conséquences fonctionnelles des polymorphismes d’intérêts ont ensuite été effectuées dans des lignées cellulaires intestinales (HT29 et Caco-2) et lymphocytaires (Jurkat). Cela nous a conduits à mieux caractériser le promoteur de Rac1 par une analyse de délétion séquentielle et par des techniques de ChIP et d’EMSA.Cette étude nous a permis de démontrer pour la première fois l’existence de polymorphismes génétiques fonctionnels de Rac1 et d’identifier son promoteur minimal, ainsi que des facteurs de transcription à l’origine de la régulation de cette protéine
Crohn’s disease (CD) and Ulcerative colitis (UC) are chronic inflammatory bowel diseases (IBD) of the gastrointestinal tract. These are multifactorial polygenic diseases with probable genetic heterogeneity. An emerging concept suggesting that dysfunction(s) of the processing of xenobiotics in the intestinal mucosa may be an important event in the initiation and progression of IBD has been discussed. Firstly, in this study, a precise and reliable characterization of the global expression profile of genes which code enzymes, transporters and nuclear factors involved in the processing of xenobiotics has been performed in intestinal epithelium of controls or patients with IBD, and in 5 intestinal cell lines. A quantitative real-time RT-PCR analysis using TaqMan Low Density Arrays (TLDA) was performed to simultaneously measure the expression of 377 genes.This work has identified genes encoding proteins that are involved in the metabolism and the disposition of xenobiotics in the healthy intestinal mucosa. Different genes expression profile between healthy and inflammatory intestinal tissues and between healthy intestinal tissues and intestinal cell lines were found. These tissues will consequently display distinctive susceptibility toward environmental chemicals and their toxic effects.Secondly, the small G protein, Rac1, which regulates cutaneous and mucosal intestinal wound healing and is identified as a target of active metabolites of thiopurine drugs, used in the treatment of IBD, has been studied. We searched for sequence variations by analysing the nucleotide sequence of the promoter and the coding sequence of Rac1 in genomic DNA from healthy volunteers and patients with IBD, using a PCR-single strand conformation polymorphism (SSCP) strategy and sequencing. The functional consequences of variations, that have been identified, were then analysed in silico and in vitro, in human intestinal cell lines (HT29 and Caco-2) and leukemia T-lymphocyte cell line (Jurkat). Via various deletion constructs, a putative regulatory region was identified and characterized further by chromatin immunoprecipitation and electrophoretic mobility shift assays.This work provides the first evidence that a functional genetic polymorphism of Rac1 activity exists. Furthermore, this study characterizes the proximal promoter of Rac1 gene and demonstrates the presence of consensus binding sites for numerous transcription factors, which could influence gene expression

A stellar spectrum is the finger-print identification of a particular star, the result of the radiation transport through its atmosphere. The physical conditions in the stellar atmosphere, its effective temperature, surface gravity, and the presence and abundance of chemical elements explain the observed features in the stellar spectra, such as the shape of the overall continuum and the presence and strength of particular lines and bands. The derivation of the atmospheric stellar parameters from a representative sample of stellar spectra collected by ground-based and spatial telescopes is essential when a realistic view of the Galaxy and its components is to be obtained. In the last decade, extensive astronomical surveys recording information of large portions of the sky have become a reality since the development of robotic or semi-automated telescopes. The Gaia satellite is one of the key missions of the European Space Agency (ESA) and its launch is planned for 2011. Gaia will carry out the so-called Galaxy Census by extracting precise information on the nature of its main constituents, including the spectra of objects (Wilkinson, 2005). Traditional methods for the extraction of the fundamental atmospheric stellar parameters (effective temperature (Teff), gravity (log G), metallicity ([Fe/H]), and abundance of alpha elements [a/Fe], elements integer multiples of the mass of the helium nucleus) are time-consuming and unapproachable for a massive survey involving 1 billion objects (about 1% of the Galaxy constituents) such as Gaia. This work presents the results of the authors’ study and shows the feasibility of an automated extraction of the previously mentioned stellar atmospheric parameters from near infrared spectra in the wavelength region of the Gaia Radial Velocity Spectrograph (RVS). The authors’ approach is based on a technique that has already been applied to problems of the non-linear parameterization of signals: artificial neural networks. It breaks ground in the consideration of transformed domains (Fourier and Wavelet Transforms) during the preprocessing stage of the spectral signals in order to select the frequency resolution that is best suited for each atmospheric parameter. The authors have also progressed in estimating the noise (SNR) that blurs the signal on the basis of its power spectrum and the application of noise-dependant algorithms of parameterization. This study has provided additional information that allows them to progress in the development of hybrid systems devoted to the automated classification of stellar spectra.

Direct-contact heat transfer between a falling liquid film and a gas stream yield high heat transfer rates and as such it is routinely used in several industrial applications. This concept has been incorporated by us into the proposed design of a novel heat exchanger for indirect cooling of steam in power plants. The DILSHE (Direct-contact Liquid-on-String Heat Exchangers) module consists of an array of small diameter (∼ 1 mm) vertical strings with hot liquid coolant flowing down them due to gravity. A low- or near-zero vapor pressure liquid coolant is essential to minimize/eliminate coolant loss. Consequently, liquids such as Ionic Liquids and Silicone oils are ideal candidates for the coolant. The liquid film thickness is of the order of 1 mm. Gas (ambient air) flowing upwards cools the hot liquid coolant. Onset of fluid instabilities (Rayleigh-Plateau and/or Kapitza instabilities) result in the formation of a liquid beads, which enhance heat transfer due to additional mixing. The key to successfully designing and operating DILSHE is understanding the fundamentals of the liquid film fluid dynamics and heat transfer and developing an operational performance map. As a first step towards achieving these goals, we have undertaken a parametric experimental and numerical study to investigate the fluid dynamics of thin liquid films flowing down small diameter strings. Silicone oil and air are the working fluids in the experiments. The experiments were performed with a single nylon sting (fishing line) of diameter = 0.61 mm and height = 1.6 m. The inlet temperature of both liquid and air were constant (∼ 20 °C). In the present set of experiments the variables that were parametrically varied were: (i) liquid mass flow rate (0.05 to 0.23 g/s) and (ii) average air velocity (0 to 2.7 m/s). Visualization of the liquid flow was performed using a high-speed camera. Parameters such as base liquid film thickness, liquid bead shape and size, velocity (and hence frequency) of beads were measured from the high-speed video recordings. The effect of gas velocity on the dynamics of the liquid beads was compared to data available in the open literature. Within the range of gas velocities used in the experiments, the occurrence of liquid hold up and/or liquid blow over, if any, were also identified. Numerical simulations of the two-phase flow are currently being performed. The experimental results will be invaluable in validation/refinement of the numerical simulations and development of the operational map.

The fabrication of arbitrary nanostructured devices in 3D space is relevant to many areas of academic and industrial research. From hybrid systems with various physical features to complex 3D optical interconnects, the added functionality gained by 3D nanomanufacturing is promising for the development of novel applications. Nevertheless, the 2D nature of conventional nanomanufacturing processes (i.e. lithography) underutilizes the 3rd dimension since there is currently no infrastructure for 3D. Nanostructured Origami has been proposed [1-3] as one solution to the 3D nanomanufacturing problem. The two-step process consists of first patterning devices and creases (axes of rotation) in 2D followed by a subsequent folding step which actuates the origamis to its final 3D shape. Several actuation mechanisms have been investigated for the folding step, and the folding of simple origamis with an open kinematic chain has been successfully demonstrated experimentally [1-3]. Since the origami segments must be accurately aligned in the 3D folded state, the actuation mechanisms for Nanostructured Origami must be both controllable and repeatable. By developing analytical models of the origamis, control schemes can be simulated to aid in the manufacturing of devices in the laboratory. As an example, a PD control scheme is introduced to achieve set-point position control of an example origami, the corner cube. In the laboratory, a PD control system would be built using a magnetic feedback mechanism. A strip of gold is patterned as a hinge material, and electrical current passes through the wire. In the presence of a magnetic field, the Lorentz force acts upon the origami segments and the resulting torque is given by τ = Cicos α,[Equation] where C is a positive constant, i is the current, and α is the angle between the magnetic field and the current. The PD control law for Nanostructured Origami is equivalent to PD control of an articulated robotic manipulator, with the exception that gravity can be ignored due to the low masses of the membranes. Instead, the stiffnesses of the hinges must be balanced, resulting in a control torque of [Equation] where τ is the vector of joint torques, G is the constraint Jacobian, Kp is the proportional control constant, Kd is the derivative control constant, K is the hinge stiffness matrix, q is the vector of joint angles, and qd is the desired steady-state values of the joint angles. This input torque is applied to the origami device, and the response is calculated by integrating the system's equations of motion [3]. The angular response of the PD controller for the corner cube origami is plotted in Fig. 1, and Fig. 2 shows a schematic of the folding of the corner cube from flat to folded state. Note the well-behaved response for a Kp value of 1500, which demonstrates zero overshoot and a rise time of approximately 15 milliseconds. A plot of the joint torques as a function of time is shown in Fig. 3. This abstract has briefly introduced the use of a PD controller for the actuation of origami devices. For a Lorentz force actuation scheme, we have demonstrated through simulations that the PD control law is stable and robust. If complicated 3D origamis with multiple closed kinematic chains are to be built, detailed control laws must be implemented. Advanced control techniques, such as optimal control, will be investigated to explore improved actuation strategies.

Three hundred eighty-six patients with acute myocardial infarction received up to 150 mg rt-PA (single chain) IV either over 8 h (60mg over 1 h, 20 mg/h for 2 h,10 mg/h for 5 h)(173 pts) or over"5h(1 mg/kg over 1 h, remainder over 4 h) (213 pts),before randomization to early or late angioplasty. Blood was collected on a lyophilized mixture of citrate and the t-PA inhibitor D-Phe-Pro-Arg-CH2C1 (PPACK), to maximally prevent in vitro fibrinolytic activation and concomitant fibrinogen degradation. The plasma rt-PA level increased to 2.4±2.0 /μg/ml(mean +SD)and 1.7 ±1.3 /μg/ml after 3h and to 1.0 ±1.8 and 1.0 ±0.9 /μg/ml at the end of the infusion.Fibrinogen levels (coagulation rate assay) fell to 5 ± 28 and 52 ± 27% at 3 h and to53 ± 28 and 47 μ 26% at the endof infusion.Fibrinogen degradation productsincreased to 32 /μg/ml (median, with 10 and 90 percentile values of 2 and 512 /μg/ml) after 3h and to3 2 /μg/1 (median, with 10 and 90 percentile values of 2and 512 ug/ml) at the end of infusion. The fibrinogen decreased to below 1 g/1 in 23% of patients and b e low 0-5 g/1 in 11% after 3 h infusion with corresponding values of 33% and 12%at the end of infusion.Thus, at the infusion rates required for rapid coronary artery reperfusion in man, rt-PA remains relatively fibrin-specific. The cause of the extensive fibrinogen depletion occurring in some patients remains to be further investigated.

In the nuclear power industry, many techniques are used to confirm that items are suitable for free-release. These techniques usually involve monitoring of the items with at least one type of radiometric instrument, to ensure that no significant quantity of man-made radioactivity is present. These monitoring techniques depend on the stage in the clearance process, the application and the size of the article being monitored. The UK Radioactive Substances Act has a Substances of Low Activity (SoLA) exemption which allows for articles and waste that have a man-made radioactive content less than 0.4 Bq g−1, to be classified as non-radioactive and be discharged from site in similar fashion to conventional wastes. Identifying whether the waste meets the criteria is technically challenging due to the low level of this exemption. Consequently the detection limits of most common portable radiation protection instrumentation is higher than this level. Historically portable alpha and beta contamination instruments are used as part of the clearance process; these are reasonably effective at monitoring the surface of an object for the presence of radioactivity, but far less so for bags of waste where alpha and beta emissions are easily absorbed within the waste. Portable gamma only contamination instruments have proved effective where some contaminants emit gamma radiation. However even these instruments have some difficulty in confirming that an article is “free” from man-made radioactivity where the mass of the article is below a critical mass. In this industry, the radioactive fingerprint will typically include an easily detectable gamma emitting radionuclide such as 60Co, or 137Cs, which may be used as a tracer for other radionuclides which cannot be easily detected with such an instrument. Installed clearance (bag) monitors are very effective where the user has a good knowledge of the radioactive fingerprint, and where there are significant (more than 10%) gamma emitting radionuclides in the fingerprint. They are ineffective where pure alpha and beta emitters dominate the radioactive fingerprint. These monitors are capable of monitoring to 1/10 of the SoLA exemption level for 60Co, with a small variation in response across the volume of the measurement chamber. Inevitably these instruments are also sensitive to NORM, so a good knowledge of NORM activity concentrations is each waste stream is required for adequate compensation. Vehicle monitors are useful for reassurance monitoring, although due to the variable nature of each waste consignment and the high background count rate, their high detection limit means they are not suitable as the sole means of free release monitoring.

The thienopyridine, PCR 4099, is a synthetic structural analog of ticlopidine. After oral administration in man, it prolongs the bleeding time (BT) and inhibits ADP-induced aggregation. The aim of the study was to evaluate the effects of oral administration of 200 mg per day PCR 4099 to 10 human volunteers for 7 days on primary hemostasis and to study the mechanism of inhibition of the drug on the ADP-fibrinogen-GPIIb-IIIa pathway of aggregation. BT (measured by a Simplate device) was 4-8 min before treatment and 30 min after 7 days of treatment. Platelets were washed and resuspended in Tyrode’s buffer containing apyrase and 0.35 % human albumin. Washed platelet suspensions were used at 37°C for aggregation and fibrinogen binding studies. Human fibrinogen was purified by successive ether precipitation and gelatin affinity chromatography to remove fibronectin. Fibrinogen was pure bv SDS-PAGE and > 95 % clottable by thrombin. It was labeled with 125I by the Iodogen method. The binding of 125I-fibrinogen to intact washed platelets exposed to ADP or thrombin was measured after centrifugation at 11 ,000 g for 1 min in the presence of 131I-human albumin as a space marker. The membrane GPIIb-IIIa complex was examined by crossed immunoelectrophoresis (CIE) in the presence of rabbit anti-human platelet antiserum. The prolonged administration of PCR 4099 inhibited almost completely platelet aggregation induced by 0.5 to 10 μM ADP. Although the effect of ADP on aggregation was blocked at high concentrations, PCR 4099 did not modify ADP-induced shape change. Only the effects of low concentrations of thrombin (< 0.05 U/ml) were inhibited by PCR 4099 administration. The binding of 125I-fibrin0gen was reduced by 50 to 90 % when platelets were stimulated by 5 μM ADP or by 0.05 U/ml thrombin. PCR 4099 did not modify the pattern of immunoprecipitates as revealed by CIE. In particular the GPIIb-IIIa complex was not dissociated and its electrophoretic mobility was not changed. In conclusion, PCR 4099, which is more potent than ticlopidine in man, inhibits specifically the ADP aggregation pathway by interfering with the binding of fibrinogen to the GPIIb-IIIa complex in platelets having undergone shape change.

Many studies have been performed with respect to the effects of fish (products) on the possible prevention of ischemic cardiovascular disease in man. Most of the trials, however, were poorly designed without a proper control group, and their results are equivocal. We, therefore, performed a well- controlled intervention trial to investigate the effect of a reasonable amount of dietary fish on certain risk indicators of arterial thrombogenesis. In Tromstf, Maastricht and Zeist, healthy male volunteers were given a dietary supplement consisting of 135 g of canned mackerel (n=40) or meat paste (control, n=42) per day for a period of 6 weeks. Compliance was monitored on the basis of the urinary excretion of lithium, added to the supplements. Average compliance was about80% and decreased slightly with time. Bleeding time was significantly prolonged and platelet number decreased in the mackerel group.Platelet aggregation inPRP induced by thrombin decreased only at a low dose.Collagen-induced platelet aggregation in PRP decreased significantly. This was associated with a 50% reduction of the collagen-induced TxB2 formation in PRP(P < 0.001). TxB3 synthesis increased significantly in the mackerel group from 0.9 to 7.8% of the TxB2 production (GC/MS). Collagen- induced platelet aggregation and ATP release in whole blood were measured with the Chronolog whole blood lumiaggregometer (Maastricht only). In the same samples TxB2 formtion was measured (RIA) and although a significant reduction was seen in the mackerel group, platelet functionswere not significantly altered. However, platelet release (but not aggregation) was significantly related to the compliance and a decreasing effect of the mackerel supplement was observed in those 50% of the volunteers having the highest compliance. This demonstrates the necessity of monitoring compliance by objective means. Acknowledgements: Financial support was obtained from the Dutch Heart Foundation. The International Association of Fish Meal Manufactures (Potters Bar, Herts, England) provided the mackerel.