This Letter presents measurements of the elliptic flow of charged particles as a function of pseudorapidity and centrality from Cu-Cu collisions at 62.4 and 200 GeV using the PHOBOS detector at the ...Relativistic Heavy Ion Collider. The elliptic flow in Cu-Cu collisions is found to be significant even for the most central events. For comparison with the Au-Au results, it is found that the detailed way in which the collision geometry (eccentricity) is estimated is of critical importance when scaling out system-size effects. A new form of eccentricity, called the participant eccentricity, is introduced which yields a scaled elliptic flow in the Cu-Cu system that has the same relative magnitude and qualitative features as that in the Au-Au system.
In relativistic heavy-ion collisions, anisotropic collective flow is driven, event by event, by the initial eccentricity of the matter created in the nuclear overlap zone. Interpretation of the ...anisotropic flow data thus requires a detailed understanding of the effective initial source eccentricity of the event sample. In this paper, we investigate various ways of defining this effective eccentricity using the Monte Carlo Glauber (MCG) approach. In particular, we examine the participant eccentricity, which quantifies the eccentricity of the initial source shape by the major axes of the ellipse formed by the interaction points of the participating nucleons. We show that reasonable variation of the density parameters in the Glauber calculation, as well as variations in how matter production is modeled, do not significantly modify the already established behavior of the participant eccentricity as a function of collision centrality. Focusing on event-by-event fluctuations and correlations of the distributions of participating nucleons, we demonstrate that, depending on the achieved event-plane resolution, fluctuations in the elliptic flow magnitude v{sub 2} lead to most measurements being sensitive to the root-mean-square rather than the mean of the v{sub 2} distribution. Neglecting correlations among participants, we derive analytical expressions for the participant eccentricity cumulants as a function of the number of participating nucleons, N{sub part}, keeping nonnegligible contributions up to O(1/N{sub part}{sup 3}). We find that the derived expressions yield the same results as obtained from mixed-event MCG calculations which remove the correlations stemming from the nuclear collision process. Most importantly, we conclude from the comparison with MCG calculations that the fourth-order participant eccentricity cumulant does not approach the spatial anisotropy obtained assuming a smooth nuclear matter distribution. In particular, for the Cu+Cu system, these quantities deviate from each other by almost a factor of 2 over a wide range in centrality. This deviation reflects the essential role of participant spatial correlations in the interaction of two nuclei.
Spinal anesthesia may reduce the incidence of morbidity that follows general anesthesia in neonates and in former preterm infants. However, bupivacaine alone provides a block too short for complete ...surgery in up to 40% of the patients. Clonidine lengthens spinal anesthesia in adults and caudal block in children without significant side effects. We conducted a controlled, prospective, dose-ranging study of clonidine in spinal anesthesia in 75 neonates, including 50% of former preterm infants, undergoing elective inguinal herniorrhaphy. Patients were given a spinal anesthetic with either 0.5% plain isobaric bupivacaine (1 mg/kg), or bupivacaine plus 0.25, 0.5, 1, or 2 μg/kg clonidine. Mean arterial blood pressure, heart rate, Spo2, sensory block extension and duration were the main data recorded. Mean arterial blood pressure, heart rate, Spo2, and block extension were similar in the five groups. Duration of spinal block increased from 67 (58–82) min in the control group up to 111 (93–125) min in the group receiving 1 μg/kg clonidine (P < 0.003). Transient hypotension occurred more often (P < 0.05), and caffeine was given more often, when 2 μg/kg clonidine was given. We conclude that 1 μg/kg clonidine provides a significant improvement in spinal anesthesia duration in newborns without significant side effects.
We present the first measurements of the pseudorapidity distribution of primary charged particles in Cu+Cu collisions as a function of collision centrality and energy, sqrts_{NN}=22.4, 62.4, and 200 ...GeV, over a wide range of pseudorapidity, using the PHOBOS detector. A comparison of Cu+Cu and Au+Au results shows that the total number of produced charged particles and the rough shape (height and width) of the pseudorapidity distributions are determined by the number of nucleon participants. More detailed studies reveal that a more precise matching of the shape of the Cu+Cu and Au+Au pseudorapidity distributions over the full range of pseudorapidity occurs for the same N{part}/2A rather than the same N_{part}. In other words, it is the collision geometry rather than just the number of nucleon participants that drives the detailed shape of the pseudorapidity distribution and its centrality dependence at RHIC energies.
In patients with dystonia, symptoms vary greatly in their extent and severity. The efficacy of pallidal stimulation is now established, but an interindividual variability in the responses to this ...treatment exists. A retrospective analysis of postoperative magnetic resonance (MR) images demonstrated millimetric variations in the positions of electrode contacts inside the posterolateroventral portion of the globus pallidus internus (GPi). It therefore seemed very likely that there is a somatotopic organization within the GPi. The goal of this study was to examine the positions of specific electrode contacts according to patients' clinical evolution, so that a somatotopic organization within the GPi could be defined.
This study included 19 patients (17 of whom were right handed) with generalized dystonia who were treated by bilateral stimulation of the GPi. Patients were examined pre- and postoperatively by using the Burke-Fahn-Marsden Dystonia Rating Scale. Dividing the patient's body into three parts--cervicoaxial area, superior limb, and inferior limb--we determined the following: 1) where the dystonic symptoms started; 2) where symptoms predominated at the time of surgery; and 3) where the highest postoperative improvement was observed. Variations in clinical response were correlated to the positions of the electrode contacts. All activated electrode contacts were in the posterolateroventral portion of the GPi (Laitinen target). A correlation between the contact location measured longitudinally and the part of the body in which the highest improvement was observed (three different areas; p = 0.004) showed that a location more anterior for the inferior limb and one more posterior for the superior limb were delineated for the right side, but not for the left side.
Inside the posterolateroventral subvolume of the GPi on the right side, three statistically different locations of electrode contacts were determined to be primary deep brain stimulation treatment sites for particular body parts in cases of dystonia.
In developing countries, Isospora belli and Cyclospora cayetanensis frequently cause chronic diarrhea in HIV-infected patients.
To compare 1 week of trimethoprim-sulfamethoxazole treatment and 1 week ...of ciprofloxacin treatment in HIV-infected patients with chronic diarrhea caused by I. belli and C. cayetanensis.
Randomized, controlled trial.
HIV clinic in Port-au-Prince, Haiti.
42 HIV-infected patients with chronic diarrhea due to I. belli (n = 22) or C cayetanensis (n = 20).
Patients were randomly assigned to receive oral trimethoprim-sulfamethoxazole (160 mg or 800 mg) or ciprofloxacin (500 mg) twice daily for 7 days. Patients who responded clinically and microbiologically received prophylaxis for 10 weeks (1 tablet orally, three times per week).
Treatment success was measured by cessation of diarrhea and negative stool examination at day 7. Prophylaxis success was measured by recurrent disease rate.
Diarrhea ceased in all 19 patients treated with trimethoprim-sulfamethoxazole. Eighteen of 19 patients had negative results on stool examination at day 7 (95%). Among the 23 patients who received ciprofloxacin, diarrhea ceased in 20 (87% CI; 66% to 97%) and 16 had negative results on stool examination at day 7 (70%). By survival analysis, diarrhea from isosporiasis and cyclosporiasis ceased more rapidly with trimethoprim-sulfamethoxazole than with ciprofloxacin. All patients receiving secondary prophylaxis with trimethoprim-sulfamethoxazole remained disease-free, and 15 of 16 patients receiving secondary prophylaxis with ciprofloxacin remained disease-free.
A 1-week course of trimethoprim-sulfamethoxazole is effective in HIV-infected patients with cyclosporiasis or isosporiasis. Although ciprofloxacin is not as effective, it is acceptable for patients who cannot tolerate trimethoprim-sulfamethoxazole.
Impaired Decision Making in Suicide Attempters Jollant, Fabrice; Bellivier, Frank; Leboyer, Marion ...
The American journal of psychiatry,
02/2005, Letnik:
162, Številka:
2
Journal Article
Recenzirano
OBJECTIVE: The understanding of suicidal behavior is incomplete. The stress-diathesis model suggests that a deficit in serotonergic projections to the orbitofrontal cortex is involved in ...susceptibility to suicidal behavior. The orbitofrontal cortex has been implicated in decision making, a cognitive function dealing with complex choices that may be under serotonergic modulation. In this preliminary study, the authors assessed decision making in suicide attempters. METHOD: The authors used the Iowa Gambling Task to investigate patients with a history of violent (N=32) or nonviolent (N=37) suicidal behavior, patients suffering from affective disorders with no history of suicidal behavior (N=25), and healthy comparison subjects (N=82). Patients were assessed when they were not suffering from a current axis I disorder. The authors also assessed the correlation of Iowa Gambling Task performance with psychometric measures of impulsivity, hostility, anger, aggression, and emotional instability. RESULTS: Both groups of suicide attempters scored significantly lower than healthy comparison subjects, and violent suicide attempters performed significantly worse than affective comparison subjects. No significant differences were observed between the groups of suicide attempters or between the two comparison groups. The differences in performance could not be accounted for by age, intellectual ability, educational level, number of suicide attempts, age at first suicide attempt, history of axis I disorder, or medication use. Iowa Gambling Task performances were correlated positively with affective lability and with anger expression but not with impulsivity. CONCLUSIONS: Impaired decision making, possibly due to emotional dysfunction, may be a neuropsychological risk factor for suicidal behavior.
Background: Although adjustable gastric banding is increasingly proposed for massively obese patients, little is known about the modifications of resting metabolic rate and substrate oxidation or ...about metabolic determinants of weight loss following this type of bariatric surgery. Objectives: To evaluate the relationships between excess weight loss, resting metabolic rate (RMR) and substrate oxidation, and to identify metabolic predictive factors of weight loss after adjustable gastric banding. Subjects: Seventy-three obese nondiabetic women aged 39.1+/-10.4 years (18.4-64.8). Design: Resting metabolic rate and substrate oxidation (indirect calorimetry), body composition (bio-impedance), lipid profile and insulin sensitivity indexes were assessed before and after (13.3+/-6.0 months, range 6.0-31.1) adjustable gastric banding. Patients were classified according to postsurgery time: group A (6-12 months, n=39); group B (12-18 months, n=21); group C (> 18 months, n=13). Metabolic parameters associated with the percentage of excess weight lost (EWL) 1 year after surgery were analyzed in univariate and multivariate regressions. Results: Mean weight loss was 26.2+/-11.4 kg. Mean fat mass loss was 17.3+/-8.1 kg. All biological parameters associated with excess weight improved after surgery. Excess weight lost at 1 year was 45.9+/-17.1% in group A, 47.4+/-17.1% in group B and 51.4+/-18.5% in group C (P=NS). Resting metabolic rate/fat-free mass (FFM) slightly decreased (28.9+/-3.26 vs 30.3+/-2.8, P<0.00001) and RMR/body weight slightly increased (18.5+/-2.8 vs 17.3+/-1.9, P<0.00001) after surgery. Respiratory quotient (0.81+/-0.06 vs 0.82+/-0.05) and FFM-adjusted lipid oxidation (1.10+/-0.41 vs 1.05+/-0.33 mg/min/kg FFM) were not significantly modified after surgery. In multiple linear regression analysis, difference in RMR/body weight, difference in energy sparing, baseline BMI and postsurgery time, were significantly and independently correlated with EWL (total R2=72.5%). Conclusions: Adjustable gastric banding promotes gradual but sustained weight loss and is associated with long-term conservation of lipid oxidation and energy expenditure. The individual variability in energy sparing mechanisms predicts weight loss during the first year after surgery.
Sports characterized by little or moderate weight bearing or impact have a low osteogenic effect. However, the action of such sports on bone turnover remains unclear. The objective of this study was ...to determine the effect on bone remodelling of physical activities that induce moderate external loading on the skeleton. Thirty-eight male athletes aged 18-39 years (cyclists, n = 11; swimmers, n = 13; triathletes, n = 14) and 10 age-matched sedentary controls aged 22-35 years participated in the study. The study combined measurement of bone mineral density by dual-energy X-ray absorptiometry and bone turnover assessment from specific biochemical markers: serum bone-specific alkaline phosphatase, osteocalcin, urinary type I collagen C-telopeptide and calcium. Compared with the controls and swimmers, adjusted bone mineral density was higher (P < 0.05) in triathletes at the total proximal femur and lower limbs. No differences in bone mineral density were found between cyclists, swimmers and controls. Compared with controls, osteocalcin was higher (P < 0.05) in triathletes and swimmers and urinary type I collagen C-telopeptide was higher in swimmers only. Serum bone-specific alkaline phosphatase was lower (P < 0.05) in cyclists than in all other groups. In conclusion, an osteogenic effect was found only in triathletes, mainly at bone sites under high mechanical stress. Bone turnover differed in athletes compared with controls, suggesting that bone turnover may be sport-practice dependent. Despite some encouraging observations, it was not possible to show that changes in the bone remodelling process were sport-discipline dependent.
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