Search

The localization of charge carriers by electronic repulsion was suggested by Mott in the 1930s to explain the insulating state observed in supposedly metallic NiO. The Mott metal–insulator transition has been subject of intense investigations ever since1–3—not least for its relation to high-temperature superconductivity4. A detailed comparison to real materials, however, is lacking because the pristine Mott state is commonly obscured by antiferromagnetism and a complicated band structure. Here we study organic quantum spin liquids, prototype realizations of the single-band Hubbard model in the absence of magnetic order. Mapping the Hubbard bands by optical spectroscopy provides an absolute measure of the interaction strength and bandwidth—the crucial parameters that enter calculations. In this way, we advance beyond conventional temperature–pressure plots and quantitatively compose a generic phase diagram for all genuine Mott insulators based on the absolute strength of the electronic correlations. We also identify metallic quantum fluctuations as a precursor of the Mott insulator–metal transition, previously predicted but never observed. Our results suggest that all relevant phenomena in the phase diagram scale with the Coulomb repulsion U, which provides a direct link to unconventional superconductivity in cuprates and other strongly correlated materials. A thorough analysis of the optical and transport properties of several two-dimensional organic conductors and insulators with varying on-site correlation strengths and bandwidths led to a quantitative phase diagram for pristine Mott insulators.

Although they have not yet been detected, axions and axion-like particles (ALPs) continue to maintain the interest (even increasingly so) of the rare-event searches community as viable candidates for the Dark Matter of the Universe but also as a solution for several other puzzles of astrophysics. Their property of coupling to photons has inspired different experimental methods for their detection, one of which is the helioscope technique. The CERN Axion Solar Telescope (CAST) is the most sensitive helioscope built up to date and has recently published part of the latest data taken with the magnet bores gradually filled with 3He, probing the mass range up to 1.17 eV. The International AXion Observatory (IAXO) is being proposed as a facility where different axion studies can be performed, with the primary goal to study axions coming from the Sun. Designed to maximize sensitivity, it will improve the levels reached by CAST by almost 5 orders of magnitude in signal detection, that is more than one order of magnitude in terms of gaγ. Here we will summarize the most important aspects of the helioscopes, and focus mainly on IAXO, based on the recent papers [1, 2].

The uptake and retention of single photon tracers in irradiated tumour cells was observed in an attempt at the early evaluation of the effect of radiation. T24 human bladder cancer cells were exposed to a single dose of 10 Gy or 20 Gy or a fractionated dose of 10 Gy (2 Gy for 5 days). The uptake of 201Tl chloride, 99Tcm-sestarnibi and 99Tcm-tetrofosmin was observed by incubating in vitrofor 60 min. The retention of the tracers was observed at 60 min after changing the incubation medium for a tracer-free medium. Uptake per culture well of all tracers in the cells exposed to 20 Gy declined as viable cell number decreased, but uptake per cell increased progressively. Uptake per cell of all tracers in the cells exposed to either a single dose or a fractionated dose of 10 Gy also increased, while a delay in growth was observed. The retention of these tracers decreased during this period and recovered thereafter. A binding assay with purified human leukocytes indicated that assessment with 99Tcm-sestamibi and 99Tcm-tetrofosmin is influenced by inflammatory cells. In conclusion, the effect of radiation may be underestimated if assessed by tracer uptake alone because of the increase in tracer uptake in viable irradiated cells. Observation of the retention of tracers may provide additional information.

In bronchial asthma, eosinophils are upregulated and their survival is suggested to be prolonged by the action of some cytokines such as Interleukin (IL)-3, IL-5 and granulocyte-macrophage colony-stimulating factor (GM-CSF). We find here that the survival of eosinophils in the peripheral blood of patients with asthma is correlated with the serum levels of IL-3 but not of IL-5 and GM-CSF. Interestingly, theophylline is revealed to induce apoptosis of the prolonged survival eosinophils by IL-3, as judged by morphological changes and nucleosomal DNA fragmentation. During the apoptosis, caspase-3 in eosinophils stimulated by IL-3 is activated by theophylline. The substrate of caspase-3, poly (ADP-ribose) polymerase (PARP), is cleaved in the eosinophils after theophylline treatment. These results suggest that theophylline is able to induce apoptosis of the IL-3 activated eosinophils in patients with bronchial asthma, and that its clinical effectiveness may be due to the reduction of inflammatory cells in the airway.

Male and female Wistar strain rats were given 0.05% N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) in their drinking water for 6 weeks and then water without BBN for 18 weeks. Diethylstilboestrol and testosterone were implanted subcutaneously into both intact and gonadectomised animals before or after treatment with BBN to evaluate their effects on the development of bladder tumours. Diethylstilboestrol reduced the incidence of bladder tumours significantly in male rats. The incidence was higher in female rats after spaying and administration of testosterone after BBN treatment, than in the intact female.-These results suggest that diethylstilboestrol inhibits carcinogenesis of the urinary bladder induced by BBN and growth of bladder tumours induced by BBN, in male rats. On the other hand, testosterone seems to stimulate the growth of bladder tumours induced by BBN in female rats.

To examine effects of bestatin on the host immunity of patients with urogenital cancer, 54 patients were randomized into 2 groups: bestatin treated and controls. In each group, the patients were divided into 2 subgroups: one which received basic treatment expected to greatly affect host immunity (‘invasive treatment’) while the other one received other types of basic treatment (‘non-invasive treatment’). Peripheral lymphocyte, OKT 4/8 ratio and purified protein derivative (PPD) skin reaction were used as immunological markers. There were significant differences in the ‘invasive’ treatment group between bestatin treated patients and controls concerning lymphocyte counts and PPD skin reactions and in the ‘non-invasive’ group concerning lymphocyte counts and OKT 4/8 ratios. These results suggest that bestatin may potentiate host immunity in patients with urogenital cancer. Further studies on larger materials are, however, needed before more definite conclusions can be drawn.

Background: Recent studies suggest that nitric oxide is important in the pathogenesis of ischemic brain injury and also has a role in controlling cerebrovascular tone. This study examines the net effects of nitric oxide on cerebral metabolic recovery after deep hypothermic circulatory arrest. Methods: Two-week-old piglets were supported by cardiopulmonary bypass and cooled to 15@? C followed by 1 hour of deep hypothermic circulatory arrest, 45 minutes of reperfusion and rewarming, and then 3 hours of normothermic perfusion. Groups of 10 piglets received one of four treatments before bypass: l-nitro-arginine methyl ester, inhibitor of nitric oxide synthesis, 10 mg/kg intravenously; l-arginine, to enhance nitric oxide synthesis, 30 mg/kg intravenously before bypass and then 10 mg/kg per minute during the first hour of reperfusion; a combination of l-nitro-arginine methyl ester plus l-arginine at these same doses; and no pretreatment (controls). Cerebral high-energy phosphates and pH were measured by magnetic resonance spectroscopy in half the animals. Cerebral blood flow, metabolic rates for oxygen and glucose, and the oxidation/reduction state of cytochrome aa3 and oxygenated and deoxygenated hemoglobin measured by near-infrared spectroscopy were assessed in the other half of the piglets. Results:l-nitro-arginine methyl ester significantly increased cerebral vascular resistance and markedly reduced recovery of high-energy phosphates, pH, and oxidation state of cytochrome aa3. l-arginine increased cerebral blood flow, cerebral glucose and oxygen consumption, and recovery of cytochrome aa3 oxidation and high-energy phosphates. l-Arginine did not reverse completely the effects of l-nitro-arginine methyl ester on cerebral metabolic recovery. Conclusion: In a piglet model of deep hypothermic circulatory arrest, l-nitro-arginine methyl ester has a deleterious effect and l-arginine has a beneficial effect on cerebral metabolic recovery. The deleterious metabolic effects of l-nitro-arginine methyl ester are only partially reversed by l-arginine. This fact suggests that there may be mechanisms in addition to inhibition of nitric oxide synthesis contributing to the neurotoxicity of l-nitro-arginine methyl ester in this model. (J THORAC CARDIOVASC SURG 1996;112:698-707)

Prior experiments on hypothermic ischemia/reperfusion have shown that (1) leukocytes have an important role in the injury resulting from hypothermic ischemia/reperfusion and (2) endothelial dysfunction with reduced release of nitric oxide occurs after hypothermic ischemia/reperfusion. l-Arginine is a nitric oxide precursor, and the effects of nitric oxide released from endothelial cells include vasorelaxation and inhibition of leukocyte adhesion to endothelium. The potential roles of an interaction between endothelial dysfunction and leukocyte-mediated injury were examined in neonatal hearts. Thirty-two isolated, blood-perfused neonatal lamb hearts were subjected to 2 hours of 10^oC cardioplegic ischemia. Group l-arginine received a 3 mmol/L dose of l-arginine during the first 20 minutes of reperfusion. In group leukocyte depletion, leukocytes were depleted (Sepacell filter) from the perfusate before reperfusion. In group l-arginine+leukocyte depletion, leukocytes were depleted and a 3 mmol/L dose of l-arginine was infused during early reperfusion. The control group had no intervention during reperfusion. At 30 minutes of reperfusion, left ventricular maximum developed pressure, positive maximum and negative maximum first derivative of left ventricular pressure (dP/dt), developed pressure at V10 (volume that produces a left ventricular enddiastolic pressure of 10 mm Hg at baseline measurement), and dP/dt at V10 were measured. Coronary blood flow was continuously monitored and oxygen consumption was also measured to evaluate the metabolic recovery. In each heart, we also tested coronary vascular resistance response to the endothelium-dependent vasodilator acetylcholine 10^-^7 mol/L and the endothelium-independent vasodilator trinitroglycerin 3x10^-^5 mol/L to assess endothelial function. Results are given as mean percent recovery of baseline values +/- standard deviation. Group l-arginine+leukocyte depletion showed significantly greater recovery of left ventricular function than the other three groups, and groups l-arginine and leukocyte depletion also showed better recovery than the control group (positive maximum dP/dt: control group = 68.3% +/- 8.8%, group l-arginine = 88.8% +/- 3.8%, group l-arginine+leukocyte depletion = 100.6% +/- 8.7%, group leukocyte depletion = 79.3% +/- 8.1%; p<0.05). Groups l-arginine and l-arginine+leukocyte depletion had higher postischemic coronary blood flow than other groups (control group = 133.0% +/- 31.6%, group l-arginine = 203.2% +/- 32.1%, group l-arginine+leukocyte depletion = 222.0% +/- 30.4%, group leukocyte depletion = 156.3% +/- 29.0%; p<0.05). Group l-arginine+leukocyte depletion showed higher oxygen consumption than the control group (control group = 76.1% +/- 19.22.1%, group l-arginine = 96.8% +/- 17.6%, group l-arginine+leukocyte depletion = 110.1% +/- 19.2%, group leukocyte depletion = 94.4% +/- 12.9%, p<0.05). Groups l-arginine, l-arginine+leukocyte depletion, and leukocyte depletion showed greater recovery of the response to acetylcholine than the control group (control group = 39.9% +/- 13.9%, group l-arginine = 61.0% +/- 14.8%, group l-arginine+ leukocyte depletion = 53.5% +/- 14.1%, group leukocyte depletion = 57.9% +/- 13.3%), but there were no intergroup differences in the response to trinitroglycerin (control group = 42.4% +/- 15.6%, group l-arginine = 36.4% +/- 15.4%, group l-arginine+leukocyte depletion = 37.7% +/- 10.2%, and group leukocyte depletion = 36.5% +/- 11.5%). Conclusion: Reperfusion with leukocyte depletion and l-arginine infusion during reperfusion have additive effects on the recovery of mechanical and endothelial function in neonatal lamb hearts. These results suggest that the beneficial effects of l-arginine involve mechanisms beyond leukocyte inhibition, most likely increased endothelial nitric oxide production.

Myocardial ischemia and reperfusion results in both ventricular and endothelial dysfunction. We have found that the endothelial defect is a reduced vasodilator response to an intraarterial infusion of acetylcholine that is likely due to reduced nitric oxide release, and we have hypothesized that reduced endothelial nitric oxide production contributes to postischemic cardiac dysfunction. However, others report that nitric oxide is deleterious after ischemia. We therefore examined the effects of infusions of l -arginine (3 mmol/L), a precursor of nitric oxide, d-arginine (3 mmol/L), an inactive stereoisomer of l-Arginine, l -nitro-arginine methyl ester (1 mmol/L); a competitive inhibitor of nitric oxide synthase, and l-nitro-arginine methyl ester (1 mmol/L) plus l-Arginine (3 mmol/L) versus controls in isolated blood-perfused neonatal lamb hearts having 2 hours of cold cardioplegic ischemia. l -nitro-arginine methyl ester was given before reperfusion, and l -arginine and d-arginine were infused for the first 20 minutes of postischemic reperfusion. At 30 minutes of reperfusion, by comparison with the control group, the l -arginine group showed significantly better recovery ( p < 0.05) of left ventricular systolic function (maximum developed pressure, developed pressure at V10 [balloon volume to produce an end-diastolic pressure of 10 mm Hg during baseline measurement], positive maximum dP/dt, and dP/dt at V10), diastolic function (negative maximum dP/dt), coronary blood flow, and endothelial function assessed by the coronary vascular resistance response to acetylcholine. The l -nitro-arginine methyl ester hearts showed a significantly poorer recovery ( p < 0.05) in left ventricular function, coronary blood flow, and endothelial function than the control group. These effects of l -nitro-arginine methyl ester were reversed to equal control values by adding a 3 mmol/L concentration of l -arginine to l -nitro-arginine methyl ester. There were no significant differences in the recovery of any variables between the d-arginine and control groups. These results point to an important salutary role for the endothelial production of nitric oxide in cardiac recovery after hypothermic ischemia in neonatal lamb hearts. The mechanism of these beneficial effects of l -arginine after ischemia and reperfusion is likely due to enhancement of the endothelial production of nitric oxide. (J T horac C ardiovasc S urg 1995;109:81-7)

The pH-stat strategy compared with the alpha-stat strategy provides more rapid recovery of brain high-energy phosphate stores and intracellular pH after 1 hour of hypothermic circulatory arrest in pigs. Possible mechanisms for this difference are (1) improved oxygen delivery and homogeneity of brain cooling before deep hypothermic circulatory arrest and (2) greater cerebral blood flow and reduced reperfusion injury owing to extracellular acidosis during the rewarming phase. To identify which of these mechanisms is predominant, we studied 49 4-week-old piglets undergoing 1 hour of deep hypothermic circulatory arrest. Four groups were defined according to cooling/rewarming strategy: alpha/alpha, alpha/pH, pH/alpha, and pH/pH. In 24 animals cerebral high-energy phosphate levels and intracellular pH were measured by magnetic resonance spectroscopy (alpha/alpha group 7, alpha/pH group 5, pH/alpha group 7, pH/pH group 5). In 25 animals cerebral blood flow was measured by labeled microspheres, cerebral metabolic rate by oxygen and glucose extraction, and the redox state of cytochrome aa"3 and hemoglobin oxygenation by near infrared spectroscopy (alpha/alpha group 7, alpha/pH group 5, pH/alpha group 7, pH/pH group 6). Cerebral blood flow was greater with pH-stat than alpha-stat during cooling (56.3% +/- 3.7% versus 32.9% +/- 2.1% of normothermic baseline values, p < 0.001). Cytochrome aa"3 values became more reduced during cooling with alpha-stat than with pH-stat (p = 0.049). Recovery of adenosine triphosphate levels in the initial 45 minutes of reperfusion was more rapid in group pH/pH compared with that in the other groups (p = 0.029). Recovery of cerebral intracellular pH in the initial 30 minutes was faster in group pH/pH compared with that in group alpha/alpha (p = 0.026). Intracellular pH became more acidic during early reperfusion only in group alpha/alpha, whereas it showed continuous recovery in the other groups. This study suggests that there are mechanisms in effect during both the cooling and rewarming phases before and after deep hypothermic circulatory arrest that could contribute to an improved cerebral outcome with pH-stat relative to more alkaline strategies. (J THORAC CARDIOVASC SURG 1995; 109: 948-58)

The effects of chronic mechanical stimulation induced by glass balls or paraffin balls on precursor lesions of the urinary bladder of male Wistar strain rats induced by N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) in the drinking water were studied.

An optical trapping method using optical fibre (optical fibre trapping method) is proposed. Optical trapping of a dielectric particle and a biological cell is successfully demonstrated. The experimental results show that a trapped micro object was easily moved and freely synchronised to the trapping fibre.

EXTREMELY halophilic bacteria, such as Halobacterium cutirubrum, grow only in high NaCl concentrations (2.5–5 M) and have very high (5 M or higher) internal concentrations of salts, mainly KCl1,2. The ribosomes and protein-synthesising systems of these organisms seem especially adapted to function in such concentrations3. In contrast, moderately halophilic bacteria, such as Vibrio costicola, grow over a much wider range of NaCl concentrations (at least 0.5–3.5 M)4. In V. costicola, though not necessarily in all moderate halophiles, the cell-associated monovalent cations are at least as concentrated as those of the external medium. For example, cells growing exponentially in medium containing 1 M NaCl and 0.008 M KC1 can have internal Na+, K+, and NH4+concentrations of about 0.6, 0.7 and 0.4 M respectively, as well as 40 mM Mg2+(ref. 5 and our unpublished results). Ribosomes from V. costicola differ from those of both extremely halophilic and non-halophilic bacteria in their ability to maintain a ‘standard’ sedimentation pattern (30, 50 and 70S) over a wide range of salt concentrations. This pattern is not changed by the NaCl concentration in which the cells are grown6. Such properties, however, do not really tell us how well the ribosomes function at different salt concentrations. Studies of in vitro protein synthesis, reported here, suggest that ribosomes may function at much lower salt concentrations than measurements of total cell-associated ions indicated to be present in the cell.

The current study evaluated the geometric accuracy of TanDEM-X twice in-situ by simultaneous observations using several corner reflectors. We set the reflectors on the flat ground, and measured the position of the reflectors before and after the satellite pass using GPS and achieved the accuracies within several centimeters. We utilized the orthorectified product which performs the correction of the geometric distortion. The results indicated that the geometric tendency of TanDEM-X is almost similar with TerraSAR-X. We also evaluated the features for correcting the geometric distortion by examining the relationships between the geometric accuracy and incidence angle of the satellites and noted that the more the incidence angle, the better the geometric accuracy proportionally. This evaluation revealed that we can actually acquire the outputs predicted by the theoretical model. The latest series of our conducted studies specify the high geometric accuracies and reliability of the specifications of the TerraSAR-X and TanDEM-X, the newest commercially available SAR satellites.