Study of the heating effect contribution to the nonlinear dielectric response of a supercooled liquid

We present a detailed study of the heating effects in dielectric measurements carried out on a liquid. Such effects come from the dissipation of the electric power in the liquid and give a contribution to the nonlinear third harmonics susceptibility chi_3 which depends on the frequency and temperature. This study is used to evaluate a possible `spurious' contribution to the recently measured nonlinear susceptibility of an archetypical glassforming liquid (Glycerol). Those measurements have been shown to give a direct evaluation of the number of dynamically correlated molecules temperature dependence close to the glass transition temperature T_g~190K (Crauste-Thibierge et al., Phys. Rev. Lett 104,165703(2010)). We show that the heating contribution is totally negligible (i) below 204K at any frequency; (ii) for any temperature at the frequency where the third harmonics response chi_3 is maximum. Besides, this heating contribution does not scale as a function of f/f_{\alpha}, with f_{\alpha}(T) the relaxation frequency of the liquid. In the high frequency range, when f/f_{\alpha} >= 1, we find that the heating contribution is damped because the dipoles cannot follow instantaneously the temperature modulation due to the heating phenomenon. An estimate of the magnitude of this damping is given.Comment: 25 pages, 10 figures, Accepted for publication in Journal of Chemical Physic

Effects of Intravenous Aspirin on Prostaglandin Synthesis and Kidney Function in Intensive Care Patients

The effects of intravenous acetylsalicylic acid (1.0 g bolus) on renal function and prostaglandin synthesis were evaluated in a prospective, controlled study in eight patients in an intensive care unit. Four of these patients had congestive heart failure. Administration of acetylsalicylic acid caused significant antidiuresis (−56%), antinatriuresis (−82%), renin suppression (−26%) and decreased GFR (−41%). All of these changes were completely reversible within 1-2 hours and tended to be more pronounced in the patients with congestive heart failure. Urinary excretion of prostaglandin E was depressed profoundly (−93%) and did not return to more than 45% of control 6 h after the administration of acetylsalicylic acid. We conclude that intravenous acetylsalicylic acid affects kidney function in a manner similar to other prostaglandin synthesis inhibitors. Its effects are, however, short-lived. The inhibition of urinary PGE2 excretion outlasts GFR depression, antidiuresis, antinatriuresis and renin suppression by several hour

Comparison of the Meat Quality of Turopolje, German Landrace x Turopolje and German Landrace x Pietrain Pigs

Aim of the study was to evaluate, if the mixed breed German Landrace x Turopolje (L x T) was suitable for conventional fattening and the production of high quality palatable meat. Hence, we chose to study the carcass characteristics of three different breeds: true bred Turopolje (T x T) (n=15), an autochthonous Croatian breed, German Landrace x Pietrain (L x P) (n=19), a typical German pig hybrid and German Landrace x Turopolje (L x T) (n=23) as mixed breed. All three breeds were kept in a conventional fattening indoor system. The data consisted of the chemical and physical values of the carcass and the difference between breeds during breeding and fattening. All pigs were fattened with a conventional ad libidum feeding system. The feed consisted of an optimal mixture for the fattening of L x P. The daily feed intake and the weight from birth until the end of the fattening was recorded every 14 days. The quality of the carcass was evaluated at the age of 20 and 25 weeks. The measurement of the carcass was based on the “Richtlinie für die Stationsprüfung auf Mastleistung, Schlachtkörperwert und Fleischbeschaffenheit beim Schwein” published by the national German control office. L x T showed the lowest feed intake per kg carcass compared to the other breeds. The quality of meat was characterized by pH, conductance, intramuscular fat and water holding capacity. L x T showed a trend for a lower conductance in week 25. The value of pH and water holding capacity was not significant between the breeds. Surprisingly, the intramuscular fat of L x T was by trend higher compared to L x P and significantly lower than T x T (p < 0.05). L x T had by trend a higher carcass weight and a larger carcass length compared to L x P, which was significantly higher than T x T (p < 0.05). In conclusion, the new breed L x T seems to be suitable for an indoor fattening system and produces a high quality palatable meat. The energy and protein intake should be slightly reduced, which would reduce the cost of meat production

Resonant Tunneling Between Quantum Hall Edge States

Resonant tunneling between fractional quantum Hall edge states is studied in the Luttinger liquid picture. For the Laughlin parent states, the resonance line shape is a universal function whose width scales to zero at zero temperature. Extensive quantum Monte Carlo simulations are presented for $\nu = 1/3$ which confirm this picture and provide a parameter-free prediction for the line shape.Comment: 14 pages , revtex , IUCM93-00

713-4 Inhibition of Vascular Superoxide Production in Hypercholesterolemic Rabbit Aorta by L-Arginine Contributes to Restored Endothelium-dependent Relaxation

Chronic oral administration of L-arginine (L-ARG) has been shown to enhance endothelial function in cholesterol (CHOL)-fed rabbits and to reduce atherogenesis. We investigated whether modulation of endogenous NO production (as assessed by urinary NO3-excretion) by L-ARG and the inhibitor of NO synthesis, L-NAME, affects vascular superoxide (O2-) production in hypercholesterolemic rabbits. Phorbol-myristate-acetate (PMA)-stimulated O2-production from isolated aortic rings was increased in rabbits given CHOL (+159±28%) or CHOL + L-NAME (+149±37%) as compared to controls (-22±7%), and endothelium-dependent relaxations by acetylcholine were diminished in both groups. In aortic rings from rabbits given CHOL + L-ARG, PMA-induced O2-production was restored to control levels (+14±17%; p&lt;0.05), and endothelium-dependent cholinergic relaxations were also partly restored. Urinary NO3-excretion decreased in all animals fed a CHOL-enriched diet (p&lt;0.01). As NO inactivated by O2-is also oxidized to NO3-, this indicates a decreased endothelial production of NO. NO3-excretion was further decreased by L-NAME (p&lt;0.05 vs. CHOL), and partly restored by L-ARG (p&lt;0.05). We conclude that both a decreased production of NO and an enhanced breakdown of NO by O2-contribute to the diminished biological activity of endothelial NO in hypercholesterolemia. L-ARG restores endothelial function by enhancing NO formation and by protecting NO from early breakdown by O2-

Restoring vascular nitric oxide formation by l-arginine improves the symptoms of intermittent claudication in patients with peripheral arterial occlusive disease

AbstractBackground. Administration of l-arginine improves nitric oxide (NO) formation and endothelium-dependent vasodilation in atherosclerotic patients.Objectives. We investigated in this double-blind, controlled study whether prolonged intermittent infusion therapy with l-arginine improves the clinical symptoms of patients with intermittent claudication, as compared with the endothelium-independent vasodilator prostaglandin E1, and control patients.Methods. Thirty-nine patients with intermittent claudication were randomly assigned to receive 2 × 8 g l-arginine/day, or 2 × 40 μg prostaglandin E1(PGE1)/day or no hemodynamically active treatment, for 3 weeks. The pain-free and absolute walking distances were assessed on a walking treadmill at 3 km/h, 12% slope, and NO-mediated, flow-induced vasodilation of the femoral artery was assessed by ultrasonography at baseline, at 1, 2 and 3 weeks of therapy and 6 weeks after the end of treatment. Urinary nitrate and cyclic guanosine-3′, 5′-monophosphate (GMP) were assessed as indices of endogenous NO production.Results. l-Arginine improved the pain-free walking distance by 230 ± 63% and the absolute walking distance by 155 ± 48% (each p < 0.05). Prostaglandin E1improved both parameters by 209 ± 63% and 144 ± 28%, respectively (each p < 0.05), whereas control patients experienced no significant change. l-Arginine therapy also improved endothelium-dependent vasodilation in the femoral artery, whereas PGE1had no such effect. There was a significant linear correlation between the l-arginine/asymmetric dimethylarginine (ADMA) ratio and the pain-free walking distance at baseline (r = 0.359, p < 0.03). l-Arginine treatment elevated the plasma l-arginine/ADMA ratio and increased urinary nitrate and cyclic GMP excretion rates, indicating normalized endogenous NO formation. Prostaglandin E1therapy had no significant effect on any of these parameters. Symptom scores assessed on a visual analog scale increased from 3.51 ± 0.18 to 8.3 ± 0.4 (l-arginine) and 7.0 ± 0.5 (PGE1; each p < 0.05), but did not significantly change in the control group (4.3 ± 0.4).Conclusions. Restoring NO formation and endothelium-dependent vasodilation by l-arginine improves the clinical symptoms of intermittent claudication in patients with peripheral arterial occlusive disease

Dual sequence definition increases the data storage capacity of sequence-defined macromolecules

Sequence-defined macromolecules offer applications in the field of data storage. Challenges include synthesising precise and pure sequences, reading stored information and increasing data storage capacity. Herein, the synthesis of dual sequence-defined oligomers and their application for data storage is demonstrated. While applying the well-established Passerini three-component reaction, the degree of definition of the prepared monodisperse macromolecules is improved compared to previous reports by utilising nine specifically designed isocyanide monomers to introduce backbone definition. The monomers are combined with various aldehyde components to synthesise dual-sequence defined oligomers. Thus, the side chains and the backbones of these macromolecules can be varied independently, exhibiting increased molecular diversity and hence data storage capacity per repeat unit. In case of a dual sequence-defined pentamer, 33 bits are achieved in a single molecule. The oligomers are obtained in multigram scale and excellent purity. Sequential read-out by tandem ESI-MS/MS verifies the high data storage capacity of the prepared oligomers per repeat unit in comparison to other sequence defined macromolecules

The Critical Behaviour of Potts models with symmetry breaking fields

The $Q$-state Potts model in two dimensions in the presence of external magnetic fields is studied. For general $Q\geq3$ special choices of these magnetic fields produce effective models with smaller $Z(Q')$ symmetry $(Q'< Q)$. The phase diagram of these models and their critical behaviour are explored by conventional finite-size scaling and conformal invariance. The possibility of multicritical behavior, for finite values of the symmetry breaking fields, in the cases where $Q>4$ is also analysed. Our results indicate that for effective models with $Z(Q')$ symmetry $(Q'\leq4)$ the multicritical point occurs at zero field. This last result is also corroborated by Monte Carlo simulations.Comment: 15 pages (standart LaTex), 2 figure (PostScript) available by request to [email protected]

Whole body and hepatic insulin action in normal, starved, and diabetic rats

In normal (N), 3-days starved (S), and streptozotocin-treated (65 mg/kg) 3-days diabetic (D) rats we examined the in vivo dose-response relationship between plasma insulin levels vs. whole body glucose uptake (BGU) and inhibition of hepatic glucose production (HGP) in conscious rats, as determined with the four-step sequential hyperinsulinemic euglycemic clamp technique, combined with [3-3H]glucose infusion. Twelve-hour fasting (basal) HGP was 3.0 +/- 0.2, 2.1 +/- 0.2, and 5.4 +/- 0.5 mg/min in N, S, and D rats, respectively. Next, all rats were clamped at matched glycemia (6 mM). Lowering plasma glucose in D rats from +/- 20 to 6.0 mM did not increase plasma norepinephrine, epinephrine, glucagon, and corticosterone levels. For BGU, insulin sensitivity was increased (70 +/- 11 microU/ml) in S and unchanged (113 +/- 21 microU/ml) in D compared with N rats (105 +/- 10 microU/ml). Insulin responsiveness was unchanged (12.4 +/- 0.8 mg/min) in S and decreased (8.5 +/- 0.8 mg/min) in D compared with N rats (12.3 +/- 0.7 mg/min). For HGP, insulin sensitivity was unchanged (68 +/- 10 microU/ml) in S and decreased (157 +/- 21 microU/ml) in D compared with N rats (71 +/- 5 microU/ml). Insulin responsiveness was identical among N, S, and D rats (complete suppression of HGP). In summary, 1) insulin resistance in D rats is caused by hepatic insensitivity and by a reduction in BGU responsiveness. 2) S rats show normal hepatic insulin action, but insulin sensitivity for BGU is increased. Therefore, S and D rats both suffering from a comparable catabolic state (10-15% body wt loss in 3 days) show opposite effects on in vivo insulin action. This indicates that in vivo insulin resistance in D rats is not caused by the catabolic state per se