Incident-energy dependence of the effective temperature in heavy-ion collisions

We study the behaviour of the effective temperature for K+ in several energy domains. For this purpose, we apply the recently developed SPheRIO code for hydrodynamics in 3+1 dimensions, using both Landau-type compact initial conditions and spatially more spread ones. We show that initial conditions given in small volume, like Landau-type ones, are unable to reproduce the effective temperature together with other data (multiplicities and rapidity distributions). These quantities can be reproduced altogether only when using a large initial volume with an appropriate velocity distribution

Shock propagation and stability in causal dissipative hydrodynamics

We studied the shock propagation and its stability with the causal dissipative hydrodynamics in 1+1 dimensional systems. We show that the presence of the usual viscosity is not enough to stabilize the solution. This problem is solved by introducing an additional viscosity which is related to the coarse-graining scale of the theory.Comment: 14 pages, 16 figure

Effect of bulk viscosity on Elliptic Flow near QCD phase transition

Effects of the bulk viscosity on the elliptic flow are studied. To introduce a realistic equation of state and transport coefficients, we apply the results of the lattice QCD and hadron resonance gas calculations for these quantities. We found that the bulk viscosity acts in a non trivial manner on the elliptic flow $v_{2}$. The reduction of $v_{2}$ is more effective at low $p_{T}$ compared to the case of shear viscosity, whereas at high $p_{T}$, the situation is reversed, leading to $v_{2}$ enhancement. We argue that this is caused by the competition of the critical behaviors of the equation of state and the transport coefficients. We further found that Grad's method with the 14 moments approximation is not applicable to estimate the viscous effects for the one-particle distribution function at the freeze out.Comment: 14 pages, 12 figure

Morbi-Mortalité des Contusions Abdominales : La Face Visible de L’iceberg

Objectif : rapporter la morbimortalité des contusions abdominales (CA) à l’hôpital national de Niamey. Patients et méthode : il s’agissait d’une étude rétrospective, descriptive et analytique sur 4 ans incluant les patients pris en charge pour CA à l’hôpital national de Niamey. Les variables étudiées étaient le sexe, l’âge, le mode de traitement, les lésions abdominales, les lésions associées, la morbidité et la mortalité. Résultats : l’étude incluait 137 patients, soit 1,6% des urgences abdominales. Il s’agissait de 116 hommes et de 27 femmes avec un sex ratio de 5,52. L’âge moyen des patients était de 22,09 ±12,3 ans. Le délai moyen d’admission était de 18,4 ±26,3 heures. Les accidents de la voie publique représentaient 49,64% des circonstances de survenue du traumatisme. La CA était isolée chez 75,2% des patients et associée à une lésion extra-abdominale chez 24,8% des patients. Cette association lésionnelle réalisait un polytraumatisme chez 18,9% des patients. Les lésions abdominales étaient dominées par les lésions spléniques survenues chez 38,6% des patients, suivies par les lésions de l’intestin grêle chez 12,4% des patients. Une complication était survenue chez 10,9% des patients et 6,5% des patients étaient décédés à l’hôpital. La survenue de complications était influencée par le délai d’admission et la survenue d’une péritonite (p=0,002). L’hémorragie était la principale cause de décès. Conclusion : les CA constituent un traumatisme de l’adulte jeune de sexe masculin. La morbimortalité des CA n’est peut être que ‘’la face visible de l’iceberg’’. Objective : to report the morbidity and the mortality of the blunt abdominal trauma (BAT) at the national hospital of Niamey. Patients and method: it was a retrospective, descriptive and analytical study over 4 years including patients managed for BAT at the national hospital of Niamey. The variables analyzed were the age, sex, treatment, abdominal organs injury, associated injury, morbidity and mortality. Results: the study included 137 patients, whether 1.6% of abdominal emergencies. They were 116 men and 27 women, with a sex ratio of 5.52. The average age was 22.09[±12.3] years old. The average intake time was 18.43[±26.3] hours. Car crashes accounted for 49.64% of the circumstances of the trauma. The BAT was isolated in 75.2% of patients and associated to a (34) extra-abdominal trauma in 24.8% of patients. This lesional association achieved polytrauma in 18.9% of patients. The most abdominal organ injured was spleen in 38.6% of patients followed by small intestine in 12.4% of patients. The morbidity rate was 10.9% and the intrahospital mortality rate was 6.5%. The occurrence of morbidity was influenced by the intake time and the occurrence of peritonitis (p=0.002). Hemorrhage was the leading cause of death. Conclusion: BAT are most frequent in young male adults at national hospital of Niamey. The morbimortality of BAT is perhaps ‘’the visible face of the iceberg’’

Fluctuations in Hadronic and Nuclear Collisions

We investigate several fluctuation effects in high-energy hadronic and nuclear collisions through the analysis of different observables. To introduce fluctuations in the initial stage of collisions, we use the Interacting Gluon Model (IGM) modified by the inclusion of the impact parameter. The inelasticity and leading-particle distributions follow directly from this model. The fluctuation effects on rapidity distributions are then studied by using Landau's Hydrodynamic Model in one dimension. To investigate further the effects of the multiplicity fluctuation, we use the Longitudinal Phase-Space Model, with the multiplicity distribution calculated within the hydrodynamic model, and the initial conditions given by the IGM. Forward-backward correlation is obtained in this way.Comment: 22 pages, RevTex, 8 figures (included); Invited paper to the special issue of Foundation of Physics dedicated to Mikio Namiki's 70th. birthda

Isotropic, Nematic and Smectic A Phase Behaviour in a Fictitious Field

Phase behaviours of liquid crystals under external fields, conjugate to the nematic order and smectic order, are studied within the framework of mean field approximation developed by McMillan. It is found that phase diagrams, of temperature vs interaction parameter of smectic A order, show several topologically different types caused by the external fields. The influences of the field conjugate to the smectic A phase, which is fictitious field, are precisely discussed.Comment: To be published in J. Phys. Soc. Jpn. vol.73 No.

Influence of Homeotropic Anchoring Walls upon Nematic and Smectic Phases

McMillan liquid crystal model sandwiched between strong homeotropic anchoring walls is studied. Phase transitions between isotropic, nematic, and smectic A phases are investigated for wide ranges of an interaction parameter and of the system thickness. It is confirmed that the anchoring walls induce an increase in transition temperatures, dissappearance of phase transitions, and an appearance of non-spontaneous nematic phase. The similarity between influence of anchoring walls and that of external fields is discussed.Comment: 5 pages, 6 figure

Prise En Charge Des Plaies Pénétrantes De L’abdomen À L’hôpital National De Niamey

Objectif : rapporter les résultats de la prise en charge des plaies pénétrantes de l’abdomen à l’hôpital national de Niamey au Niger. Patients et méthodes : il s’agissait d’une étude rétrospective et descriptive sur une période de 2 ans. L’étude a concerné tous les patients de tout âge pris en charge à l’hôpital national de Niamey pour plaie pénétrantes de l’abdomen. Résultats : l’étude incluait 51 patients, soit 0,88% des traumatismes. Il s’agissait de 6 femmes et 45 hommes, soit un sex ratio de 7,5. L’âge moyen des patients était de 28 ans [±10,2]. Le délai moyen d’admission était de 4,86 heures [±2,08]. Dans 84,32% des cas les patients étaient transportés à l’hôpital dans un véhicule non médicalisé. Les agressions représentaient 78,44% des circonstances de survenue et la plaie abdominale s’intégrait dans un contexte de polytraumatisme chez 21,53% des patients. Une éviscération était présente chez 31,37% des patients. Le traitement était opératoire chez 90,19% des patients avec 19,56% de laparotomie non thérapeutique. L’organe le plus lésé était l’intestin grêle dans 31,37% des cas suivi du colon dans 23,52% des cas. La morbidité globale était de 33,37% dominée par les hémorragies postopératoires dans 8,69% des cas. La mortalité était de 13,73% avec 50,14% de décès en postopératoire immédiat par hémorragie secondaire ; 28,58% de décès par retard de l’hémostase chirurgicale et 14,28% de décès par défaut de compensation des pertes sanguines en urgence.Conclusion : les plaies de l’abdomen sont fréquentes chez l’adulte jeune de sexe masculin. Elles sont souvent dues à une agression par armes blanches avec un taux élevé de décès. Objective: to report the results of the management of the penetrating abdominal wounds at the national hospital of Niamey. Patients and method: it was a retrospective and descriptive study over 2 years. The study included the patients of all ages managed for penetrating abdominal wounds at national hospital of Niamey in Niger. Results: the study includes 51 patients whether 0.88 % of trauma. They were 45 men and 6 women, with a sex ratio of 7.5. The average age was 28 [±10.2] years old. The average intake time was 4.86 [2.08] hours. In 84. 32% of cases, patients were transported to the hospital in non-medical vehicle. The assault accounted for 78.44% of the circumstances of the occurrence and the penetrating abdominal wound was integrated into a polytrauma in 21.53% of cases. An evisceration was present in 31.37 % of cases. The management was operative in 90.19% of cases with 19.56% of non-therapeutic laparotomy. The most injured organ was the small intestine in 31.37% of cases followed by the colon in 23.52% of cases. The overall morbidity was 33.37%, dominated by postoperative hemorrhages in 8.69% of cases. The mortality was 13.73% with 50.14% of immediate deaths by secondary hemorrhage, 28.58% of deaths by delay of the surgical hemostasis and 14.28% of deaths by a failure of compensation of the blood losses in emergency room. Conclusion: the penetrating abdominal wounds are common in young adult males. They are often due to a stabbing assault with a high death rate