Mass accretion rates of clusters of galaxies: CIRS and HeCS

We use a new spherical accretion recipe tested on N-body simulations to measure the observed mass accretion rate (MAR) of 129 clusters in the Cluster Infall Regions in the Sloan Digital Sky Survey (CIRS) and in the Hectospec Cluster Survey (HeCS). The observed clusters cover the redshift range of $0.01<z<0.30$ and the mass range of $\sim 10^{14}-10^{15} {h^{-1}~\rm{M_\odot}}$. Based on three-dimensional mass profiles of simulated clusters reaching beyond the virial radius, our recipe returns MARs that agree with MARs based on merger trees. We adopt this recipe to estimate the MAR of real clusters based on measurements of the mass profile out to $\sim 3R_{200}$. We use the caustic method to measure the mass profiles to these large radii. We demonstrate the validity of our estimates by applying the same approach to a set of mock redshift surveys of a sample of 2000 simulated clusters with a median mass of $M_{200}= 10^{14} {h^{-1}~\rm{M_{\odot}}}$ as well as a sample of 50 simulated clusters with a median mass of $M_{200}= 10^{15} {h^{-1}~\rm{M_{\odot}}}$: the median MARs based on the caustic mass profiles of the simulated clusters are unbiased and agree within $19\%$ with the median MARs based on the real mass profile of the clusters. The MAR of the CIRS and HeCS clusters increases with the mass and the redshift of the accreting cluster, which is in excellent agreement with the growth of clusters in the $\Lambda$CDM model.Comment: 25 pages, 19 figures, 7 table

Epigenetic Analysis in Human Neurons: Considerations for Disease Modeling in PD

Parkinson’s disease (PD) is the second most common neurodegenerative disorder next to Alzheimer’s disease. Most PD cases are considered to be sporadic and despite considerable scientific effort, the underlying cause(s) still remain(s) enigmatic. In particular, it is unknown to which extent epigenetic alterations contribute to the pathophysiology of this devastating disorder. This is partly due to the fact that appropriate PD models are not yet available. Moreover, epigenetic patterns and mechanisms are species specific and murine systems reflect only a few of the idiosyncrasies of human neurons. For several years now, patient-specific stem cell-derived neural and non-neural cells have been employed to overcome this limitation allowing the analysis and establishment of humanized disease models for PD. Thus, several studies tried to dissect epigenetic alterations such as aberrant DNA methylation or microRNA patterns using lund human mesencephalic cell lines or neurons derived from (patient-specific) induced pluripotent stem cells. These studies demonstrate that human neurons have the potential to be used as model systems for the study of epigenetic modifications in PD such as characterizing epigenetic changes, correlating epigenetic changes to gene expression alterations and hopefully using these insights for the development of novel therapeutics. However, more research is required to define the epigenetic (age-associated) landscape of human in vitro neurons and compare these to native neurons before they can be established as suitable models for epigenetic studies in PD. In this review, we summarize the knowledge about epigenetic studies performed on human neuronal PD models, and we discuss advantages and current limitations of these (stem cell-derived) neuronal models for the study of epigenetic alterations in PD

Resonant nonlinear absorption in Zn-phthalocyanines

In this work, we investigate the nonlinear absorption dynamics of Zn phthalocyanine in dimethyl sulfoxide (DMSO). We used single pulse and pulse train Z-scan techniques to determine the dynamics and absorption cross-sections of singlet and triplet states at 532 nm. The excited singlet state absorption cross-section was determined to be 3.2 times higher than the ground state one, giving rise to reverse saturable absorption. We also observed that reverse saturable absorption occurs from the triplet state, after its population by intersystem crossing, whose characteristic time was determined to be 8.9 ns. The triplet state absorption cross-section determined is 2.6 times higher than the ground state one. In addition, we used the white light continuum Z-scan to evaluate the singlet excited state spectrum from 450 to 710 nm. The results show two well-defined regions, one above 600 nm, where reverse saturable absorption is predominant. Below 600 nm, we detected a strong saturable absorption. A three-energy-level diagram was used to explain the experimental results, leading to the excited state absorption cross-section determination from 450 nm up to 710 nm.FAPESPCNPQAFOSR (FA9550- 07-1-0374

Treatment of iatrogenic and traumatic tracheal disruptions

Background and aim. The optimal management of tracheal disruptions is still controversial. It is usually postulated that lesions wider than 1 or 2 centimetres and/or lesions of full-thickness should be treated by surgery at an early stage. Such a statement is not supported by any proven evidence. On the contrary, the conservative management of such injuries has also produced very good results according to recent reports. The aim of this study is to investigate whether conservative treatment can be safely used for wide tracheal lacerations and to assess any possible association between clinical features and modality of treatment. Methods. Records of all patients with iatrogenic and traumatic tracheal disruptions observed between January 1992 and December 2006 were collected and retrospectively reviewed. Data regarding mechanism of injury, clinical and morphological features and modalities of treatment were registered. All possible associations between clinical features and modalities of treatment were investigated. Results. 23 patients were observed overall. There were 6 males and 17 females with a median age of 58 years (range 20-84 yrs). 15 patients had undergone single tube intubation. One patient had his trachea injured during an esophagectomy. Ruptures were secondary to blunt (n=5) and open (n=2) trauma in 7 patients. Lesions varied in length between 1 and 7 centimetres (median length 3 centimetres) and all were full-thickness. The time interval until diagnosis varied between 0 and 72 hours (median 6 hours). Respiratory failure was evident in 7 patients. 16 patients (69.5%) with lacerations ranging in length between 1 and 5.5 centimetres (median length 2.75 cm) underwent conservative treatment. Seven patients (30.5%) underwent surgery. The follow up was completed for 16 patients and varied between 15 and 105 months (median 22.5). One patient died after surgical treatment. No mortality or late major sequelae were registered after conservative treatment. Female sex, absence of respiratory failure and delayed diagnosis was associated with the conservative treatment. Conclusions. Conservative treatment can play a major role even in cases of wide tracheal lacerations. Clinical rather than morphological features should be regarded as main criteria for treatment. The conservative treatment is particularly indicated in the case of stable respiratory parameters independent of the size and the depth of the lesion