The compositional construction of Markov processes II

In an earlier paper we introduced a notion of Markov automaton, together with parallel operations which permit the compositional description of Markov processes. We illustrated by showing how to describe a system of n dining philosophers, and we observed that Perron-Frobenius theory yields a proof that the probability of reaching deadlock tends to one as the number of steps goes to infinity. In this paper we add sequential operations to the algebra (and the necessary structure to support them). The extra operations permit the description of hierarchical systems, and ones with evolving geometry

Slow dynamics in a primitive tetrahedral network model

We report extensive Monte Carlo and event-driven molecular dynamics simulations of the fluid and liquid phase of a primitive model for silica recently introduced by Ford, Auerbach and Monson [J. Chem. Phys. 17, 8415 (2004)]. We evaluate the iso-diffusivity lines in the temperature-density plane to provide an indication of the shape of the glass transition line. Except for large densities, arrest is driven by the onset of the tetrahedral bonding pattern and the resulting dynamics is strong in the Angell's classification scheme. We compare structural and dynamic properties with corresponding results of two recently studied primitive models of network forming liquids -- a primitive model for water and a angular-constraint free model of four-coordinated particles -- to pin down the role of the geometric constraints associated to the bonding. Eventually we discuss the similarities between "glass" formation in network forming liquids and "gel" formation in colloidal dispersions of patchy particles.Comment: 9 pages, 10 figure

External ultrasound-assisted lipectomy: effects on abdominal adipose tissue

The use of ultrasound “on the surface” was hypothesized by Scuderi et al. in 19871 and resumed by Zocchi in 1996.2 Ultrasound-assisted liposuction is as a technique that can be associated with suctionassisted lipectomy.3 This new technique is called external ultrasound-assisted lipectomy. Whereas ultrasound- assisted liposuction emulsifies adipose tissue due to adipocyte membrane lysis, external ultrasound- assisted lipectomy, being less “invasive,” induces cell-to-cell contact loss and alters collagenic fibers. This leads to an easier detachment of adipose cells, which remain unaltered and can be mechanically removed. The external ultrasound-assisted lipectomy technique is the transcutaneous application of ultrasound by means of high-frequency ultrasound upon massive infiltrated tissue, followed by traditional liposuction. Results showed that several different effects were detected on both adipocytes and collagen fibers

High concordance between trained nurses and gastroenterologists in evaluating recordings of small bowel video capsule endoscopy (VCE)

Background & Aims: The video capsule endoscopy (VCE) is an accurate and validated tool to investigate the entire small bowel mucosa, but VCE recordings interpretation by the gastroenterologist is time-consuming. A pre-reading of VCE recordings by an expert nurse could be accurate and cost saving. We assessed the concordance between nurses and gastroenterologists in detecting lesions on VCE examinations. Methods: This was a prospective study enrolling consecutive patients who had undergone VCE in clinical practice. Two trained nurses and two expert gastroenterologists participated in the study. At VCE pre-reading the nurses selected any abnormalities, saved them as “thumbnails” and classified the detected lesions as a vascular abnormality, ulcerative lesion, polyp, tumor mass, and unclassified lesion. Then, the gastroenterologist evaluated and interpreted the selected lesions and, successively, reviewed the entire video for potential missed lesions. The time for VCE evaluation was recorded. Results: A total of 95 VCE procedures performed on consecutive patients (M/F: 47/48; mean age: 63 ± 12 years, range: 27−86 years) were evaluated. Overall, the nurses detected at least one lesion in 54 (56.8%) patients. There was total agreement between nurses and gastroenterologists, no missing lesions being discovered at a second look of the entire VCE recording by the physician. The pre-reading procedure by nurse allowed a time reduction of medical evaluation from 49 (33-69) to 10 (8-16) minutes (difference:-79.6%). Conclusions: Our data suggest that trained nurses can accurately identify and select relevant lesions in thumbnails that subsequently were faster reviewed by the gastroenterologist for a final diagnosis. This could significantly reduce the cost of VCE procedure

Very Large Telescope Observations of the peculiar globular cluster NGC6712. Discovery of a UV, H-alpha excess star in the core

We present results from multi-band observations in the central region of the cluster NGC6712 with the ESO-Very Large Telescope. Using high resolution images we have identified three UV-excess stars. In particular two of them are within the cluster core, a few arcsec apart: the first object is star "S" which previous studies identified as the best candidate to the optical counterpart to the luminous X-ray source detected in this cluster. The other UV object shows clearcut H-alpha emission and, for this reason, is an additional promising interacting binary candidate (a quiescent LMXB or a CV). The presence of two unrelated interacting binary systems a few arcsec apart in the core of this low-density cluster is somewhat surprising and supports the hypothesis that the (internal) dynamical history of the cluster and/or the (external) interaction with the Galaxy might play a fundamental role in the formation of these peculiar objects.Comment: 15 pages, 3 figures. ApJL in pres

Magnetic Control of Transmission and Helicity of Nano-Structured Optical Beams in Magnetoplasmonic Vortex Lenses

We theoretically investigate the generation of far-field propagating optical beams with a desired orbital angular momentum by using an archetypical magnetoplasmonic tip surrounded by a gold spiral slit. The use of a magnetic material can lead to important implications once magneto-optical activity is activated through the application of an external magnetic field. The physical model and the numerical study presented here introduce the concept of magnetically tunable plasmonic vortex lens, namely a magnetoplasmonic vortex lens, which ensures a tunable selectivity in the polarization state of the generated nanostructured beam. The presented system provides a promising platform for a localized excitation of plasmonic vortices followed by their beaming in the far-field with an active modulation of both light's transmittance and helicity

Human Adipose Stem Cells: From Bench to Bed-Side

Stem cell-based therapies for repair and regeneration of different tissues are becoming more important in the treatment of several diseases. Adult stem cells currently symbolize the most available source of cell progenitors for tissue engineering and repair and can be harvested using minimally invasive procedures. Moreover, mesenchymal stem cells (MSCs), the most widely used stem cells in stem cell-based therapies, are multipotent progenitors, with capability to differentiate into cartilage, bone, connective, muscle, and adipose tissue. So far, bone marrow has been regarded as the main source of MSCs. To date, human adult adipose tissue may be the best suitable alternative source of MSCs. Adipose stem cells (ASCs) can be largely extracted from subcutaneous human adult adipose tissue. A large number of studies show that adipose tissue contains a biologically and clinically interesting heterogeneous cell population called stromal vascular fraction (SVF). The SVF may be employed directly or cultured for selection and expansion of an adherent population, so called adipose-derived stem cells (ASCs). In recent years, literature based on data related to SVF cells and ASCs has augmented considerably: These studies have demonstrated the efficacy and safety of SVF cells and ASCs in vivo in animal models. On the basis of these observations, in several countries, various clinical trials involving SVF cells and ASCs have been permitted. This review aims at summarizing data regarding either ASCs cellular biology or ASCs-based clinical trials and at discussing the possible future clinical translation of ASCs and their potentiality in cell-based tissue engineering

Multiwavelength study of RX J2015.6+3711: a magnetic cataclysmic variable with a 2-hr spin period

The X-ray source RX J2015.6+3711 was discovered by ROSAT in 1996 and recently proposed to be a cataclysmic variable (CV). Here we report on an XMM-Newton observation of RX J2015.6+3711 performed in 2014, where we detected a coherent X-ray modulation at a period of 7196+/-11 s, and discovered other significant (>6sigma) small-amplitude periodicities which we interpret as the CV spin period and the sidebands of a possible ~12 hr periodicity, respectively. The 0.3-10 keV spectrum can be described by a power law (Gamma = 1.15+/-0.04) with a complex absorption pattern, a broad emission feature at 6.60+/-0.01 keV, and an unabsorbed flux of (3.16+/-0.05)x10^{-12} erg/s/cm^2. We observed a significant spectral variability along the spin phase, which can be ascribed mainly to changes in the density of a partial absorber and the power law normalization. Archival X-ray observations carried out by the Chandra satellite, and two simultaneous X-ray and UV/optical pointings with Swift, revealed a gradual fading of the source in the soft X-rays over the last 13 years, and a rather stable X-ray-to-optical flux ratio (F_X/F_V ~1.4-1.7). Based on all these properties, we identify this source with a magnetic CV, most probably of the intermediate polar type. The 2 hr spin period makes RX J2015.6+3711 the second slowest rotator of the class, after RX J0524+4244 ("Paloma", P_spin~2.3 hr). Although we cannot unambiguously establish the true orbital period with these observations, RX J2015.6+3711 appears to be a key system in the evolution of magnetic CVs.Comment: 11 pages, 8 figures, accepted for publication on MNRA