Bimodality and Latent Heat of Gold Nuclei

Peripheral collisions give access to a set of events where hot quasi-projectile (QP) sources are produced exploring a large range of excitation energy. In this range evaporation and multifragmentation are both observed for a similar charge/size of the sources. In this work, this experimental fact will be described in terms of coexistence of two classes of events in the first order phase transition formalism. For this, a detailed study of the experimental correlation between the size/charge of the biggest cluster/fragment (Z1) and the excitation energy (E*) is made. Making the parallel with the same correlation derived from the canonical ensemble description, a first value of the latent heat and boundaries of spinodal and coexistence zone are extracted.Comment: 7 page

zt: A Sofware Tool for Simple and Partial Mantel Tests

Different methods of data analysis (e.g. clustering and ordination) are based on distance matrices. In some cases, researchers may wish to compare several distance matrices with one another in order to test a hypothesis concerning a possible relationship between these matrices. However, this is not always self-evident. Usually, values in distance matrices are, in some way, correlated and therefore the usual assumption of independence between objects is violated in the classical tests approach. Furthermore, often, spurious correlations can be observed when comparing two distances matrices. A classic example is the comparison between genetic and environmental distances. Colonies that are in close proximity of each other tend to have similar environments and therefore there will be a positive correlation between environmental and geographical distances. Such colonies will also be more likely to exchange migrants so that genetic distances will be positively correlated with spatial distances. The consequence is that an observed positive association between genetic and environmental distances may be simply due to spatial effects. The most widely used method to account for distance correlations is a procedure known as the Mantel test (Mantel,'67; Mantel and Valand,'70 following the pioneering work of Daniels,'44 ; Daniels and Kendall'47). The simple Mantel test considers two matrices while an extension known as the partial Mantel test considers three matrices. These tools are widely used in different fields of research such as population genetics, ecology, anthropology, psychometrics and sociology.

Using convolutional neural networks for the classification of breast cancer images

In this study I compare different architectures of convolutional neural networks and different hardware acceleration devices for the detection of breast cancer from microscopic images of sentinel lymph nodes tissue. Convolutional models with increasing depth are trained and tested on a public data set of more than 300,000 images of lymph node tissue, on four different hardware acceleration cards, using an off-the-shelf deep learning framework. The impact of transfer learning, data augmentation and hyperparameters fine-tuning are also tested. Hardware acceleration device performance can improve training time by a factor of five to twelve, depending on the model used. On the other hand, increasing convolutional depth will augment the training time by a factor of four to six times, depending on the acceleration device used. Increasing the depth of the model, as could be expected, clearly improves performance, while data augmentation and transfer learning do not. Fine-tuning the hyperparameters of the model notably improves the results, with the best model showing a performance comparable to state-of-the-art models.Comment: 9 pages, 2 figures, 4 tables; corrected typos; added one more (recent) GPU car

New and emerging agents in the management of lipodystrophy in HIV-infected patients

Lipodystrophy remains a major long-term complication in human immunodeficiency virus-infected patients under antiretroviral (ARV) therapy. Patients may present with lipoatrophy or lipohypertrophy or both. The choice of treatments to improve fat redistribution depends on the form of lipodystrophy and its duration. Measures known to improve lipoatrophy are switches in ARV therapy (stavudine or zidovudine to abacavir or tenofovir) and filling interventions. Pioglitazone may be added to these measures, although any benefits appear small. Uridine and leptin were found to be disappointing so far. Regarding lipohypertrophy, diet and exercise, recombinant human growth hormone, and metformin may reduce visceral fat, but may worsen subcutaneous lipoatrophy. Surgical therapy may be required. Attractive pharmacologic treatments include growth hormone-releasing factor and leptin. Adiponectin and adiponectin receptors are promising therapeutic targets to explore

What Can be Learned Studying the Distribution of the Biggest Fragment ?

In the canonical formalism of statistical physics, a signature of a first order phase transition for finite systems is the bimodal distribution of an order parameter. Previous thermodynamical studies of nuclear sources produced in heavy-ion collisions provide information which support the existence of a phase transition in those finite nuclear systems. Some results suggest that the observable Z1 (charge of the biggest fragment) can be considered as a reliable order parameter of the transition. This talk will show how from peripheral collisions studied with the INDRA detector at GSI we can obtain this bimodal behaviour of Z1. Getting rid of the entrance channel effects and under the constraint of an equiprobable distribution of excitation energy (E*), we use the canonical description of a phase transition to link this bimodal behaviour with the residual convexity of the entropy. Theoretical (with and without phase transition) and experimental Z1-E* correlations are compared. This comparison allows us to rule out the case without transition. Moreover that quantitative comparison provides us with information about the coexistence region in the Z1-E* plane which is in good agreement with that obtained with the signal of abnormal uctuations of configurational energy (microcanonical negative heat capacity).Comment: 8 page

Investigation of collective radial expansion and stopping in heavy ion collisions at Fermi energies

We present an analysis of multifragmentation events observed in central Xe+Sn reactions at Fermi energies. Performing a comparison between the predictions of the Stochastic Mean Field (SMF) transport model and experimental data, we investigate the impact of the compression-expansion dynamics on the properties of the final reaction products. We show that the amount of radial collective expansion, which characterizes the dynamical stage of the reaction, influences directly the onset of multifragmentation and the kinematic properties of multifragmentation events. For the same set of events we also undertake a shape analysis in momentum space, looking at the degree of stopping reached in the collision, as proposed in recent experimental studies. We show that full stopping is achieved for the most central collisions at Fermi energies. However, considering the same central event selection as in the experimental data, we observe a similar behavior of the stopping power with the beam energy, which can be associated with a change of the fragmentation mechanism, from statistical to prompt fragment emission.Comment: 15 page

Un teatre de l’experience

En janvier 1993, j’eus le privilège de visiter, dans la banlieue de Moscou, un abri antiatomique qui venait de perdre sa fonction initiale pour les habitants, c’était la fin de la guerre froide. L’espace immense, devenu un entrepôt, était cloisonné de grilles, en un vaste vide grenier. Dans une des cellules de cet espace, un jeune historien d’art élaborait et conservait l’une des premières collections d’art moderne et contemporain de Russie. Œuvres faisant référence à l’art américain, que les artistes d’URSS découvraient sur des revues en noir et blanc diffusées clandestinement, installations réalisées par l’underground moscovite, stigmatisant les pratiques staliniennes. L’ensemble constituait une documentation irremplaçable sur la résistance des artistes et pour une renaissance d’un art vivant en Russie. L’évocation de cet abri réel devenant un réceptacle d’archive muséale, me permet d’introduire la fiction de Dominique Gonzalez-Foerster. TH 2058 qui transforme un musée en abri. La fiction rencontre ici le réel d’une manière inversée

Partir y volver. Cuba, tierra natal de Wifredo Lam y Ana Mendieta

From the word Heimat, feedback processes are analyzed. From the experience of this event, the article explores the trails of the artists Wifredo Lam y Ana Mendieta.Tomando como punto de partida la palabra Heimat se analizan los procesos deida-vuelta. A partir de la vivencia de este acontecimiento se analizan los derroteros de loscreadores Wifredo Lam y Ana Mendieta.A partir da palavra Heimat se analisa os processos de ida-volta. A partir da vivencia deste acontecimento se analisam as trajetórias dos criadores Wilfredo Lam e Ana Mendieta

Suppression of Aggregation in Natural-Semiflexible/Flexible Polyanion Mixtures, and Direct Check of the OSF Model using SANS

Aggregation and other interactions are suppressed for a biological semiflexible polyelectrolyte, hyaluronan (HA), when it is embedded in a mixture with another negatively charged and flexible polyelectrolyte chain, sodium polystyrene sulfonate. We see directly HA only in the mixture using Small-Angle Neutron Scattering, isotopic labelling and contrast matching. At low ionic strength, for which aggregation is usually seen for pure HA solutions, an unambiguous set of experimental results shows that we neither observe HA aggregation nor a polyelectrolyte peak (observed for solutions of single species); instead we observe a wormlike chain behaviour characteristic of single chain with a variation of the persistence length with the square of the Debye screening length, Le~\kappa^-2, as formerly predicted by Odijk and not yet observed on a polymer chain