Behavior of hydrogen ions, atoms, and molecules in a-boron studied using density functional calculations

We examine the behavior of hydrogen ions, atoms, and molecules in a-boron using density functionalcalculations. Hydrogen behaves as a negative-U center, with positive H ions preferring to sit off-center oninterlayer bonds and negative H ions sitting preferably at in-plane sites between three B12 icosahedra. Hydrogen atoms inside B12 icosahedral cages are unstable, drifting off-center and leaving the cage with only a 0.09 eV barrier. While H0 is extremely mobile (diffusion barrier 0.25 eV), H+ and H- have higher diffusion barriers of 0.9 eV. Once mobile, these defects will combine, forming H2 in the interstitial void space, which will remain trapped in the lattice until high temperatures. Based on these results we discuss potential differences for hydrogen behavior in -boron and compare with experimental muon-implantation data

Electric pulse induced electronic patchwork in the Mott insulator GaTa4Se8

Following a recent discovery of the Insulator-to-Metal Transition induced by electric field in GaTa4Se8, we performed a detailed Scanning Tunneling Microscopy/Spectroscopy study of both pristine (insulating) and transited (conducting) crystals of this narrow gap Mott insulator. The spectroscopic maps show that pristine samples are spatially homogeneous insulators while the transited samples reveal at nanometer scale a complex electronic pattern that consists of metallic and superinsulating patches immersed in the pristine insulating matrix. Surprisingly, both kinds of patches are accompanied by a strong local topographic inflation, thus evidencing for a strong electron-lattice coupling involved in this metal-insulator transition. Finally, using a strong electric field generated across the STM tunneling junction, we demonstrate the possibility to trig the metal-insulator transition locally even at room temperature

Radio hyperthermia for re-treatment of superficial tumours.

Relapse remains an unsolved problem for previously radio-treated patients. Our purpose is to evaluate the role of radio-hyperthermia (RT-HT) in the retreatment of superficial recurrences.From 1998 to 2007, 51 patients affected by four histological types (breast recurrences (group A), melanoma recurrences (group B), head and neck recurrences (group C), and others (group D)) of 76 superficial lesions, were enrolled at Mauriziano Hospital at the Research Institute of Cancer Care Candiolo (IRCC) in Turin. All patients had previously undergone RT except 6 patients of group B. The total mean retreatment dose was 31.8 Gy (20-60 Gy), while the mean of HT sessions was 5 (1 to 8), temperature ranged from 38.5 degrees C (T min) to 44 degrees C (T max).Acute cutaneous toxicity was 77.6% G1, 22.4% G2, none for G3. Forty-five days later we observed: for group A 65.9% complete response (CR), 29.5% partial response (PR), 4.5% non-response (NR); for group B 33.3% CR, 25% PR and 41.7% NR; for group C 40% CR, 13.3% PR, 46.7% NR, for group D 60% CR and 40% NR. 18 months later group A presented 72.7% local control (LC), 20.5% stable disease (SD) and 6.8% non-control (NC), group B 50% LC, 16,7% SD and 33.3% NC, group C 33.3% LC, 40% SD and 26.7% NC, group D 40% LC and 60% NC. Early response, size of lesionsor =3 cm, T maxor =42 degrees C and RT dosesor =40 Gy were predictive outcome factors.We confirmed that radio-hyperthermia is useful in re-irradiation with a very high patient compliance

Microsurgical third ventriculocisternostomy as an alternative to ETV: report of two cases

OBJECTIVE: To describe a microsurgical alternative to endoscopic third ventriculocisternostomy. METHODS: Two children with shunt-dependent hydrocephalus and multiple shunt revisions were considered candidates for third ventriculocisternostomy (TVS). Because of slit ventricles, an endoscopic approach was not possible and, therefore, both patients received a microsurgical TVS by a supraorbital approach. RESULTS: In both cases, microsurgical TVS was successful and the patients became shunt free. CONCLUSION: Microsurgical TVS by a supraorbital craniotomy is a viable alternative to endoscopic TVS in selected cases

In vitro initial attachment of HIV-1 integrase to viral ends: control of the DNA specific interaction by the oligomerization state

HIV-1 integrase (IN) oligomerization and DNA recognition are crucial steps for the subsequent events of the integration reaction. Recent advances described the involvement of stable intermediary complexes including dimers and tetramers in the in vitro integration processes, but the initial attachment events and IN positioning on viral ends are not clearly understood. In order to determine the role of the different IN oligomeric complexes in these early steps, we performed in vitro functional analysis comparing IN preparations having different oligomerization properties. We demonstrate that in vitro IN concerted integration activity on a long DNA substrate containing both specific viral and nonspecific DNA sequences is highly dependent on binding of preformed dimers to viral ends. In addition, we show that IN monomers bound to nonspecific DNA can also fold into functionally different oligomeric complexes displaying nonspecific double-strand DNA break activity in contrast to the well known single strand cut catalyzed by associated IN. Our results imply that the efficient formation of the active integration complex highly requires the early correct positioning of monomeric integrase or the direct binding of preformed dimers on the viral ends. Taken together the data indicates that IN oligomerization controls both the enzyme specificity and activity

Multidisciplinary approach to reconstructing local pastoral activities: an example from the Pyrenean Mountains (Pays Basque)

International audienceIn this study archaeology, history and palaeoecology (modern and fossil data sets of pollen and nonpollen palynomorphs) were used to reconstruct small-scale pastoral activities in the Pyrenees Mountains during the last two millennia. Modern pollen assemblages from the major vegetation units (both natural andanthropogenic) are studied on one restricted watershed area. A correlative model (RDA) of 61 modern pollen spectra and 35 external variables distinguishes two groups of taxa, providing information on the nature and spatial extent of human impact on the landscape. The first pool indicates local pastoral activities, and the second one implies regional input from outside the studied watershed, and is not characteristic of a specific land use. These pools are described as 'Local Pastoral Pollen Indicators' (LPPI) for this particular mountain region on crystalline bedrock and 'Regional Human Activities Pollen Indicators' (RHAPI). The modern data set is used to aid interpretation of the local pollen sequence of Sourzay that covers the last 2000 calendar years BP, using RDA reconstructions, and best modern analogues as a means of comparing modern and fossil spectra. The study also demonstrates agreement between the independent interpretations of two fossil proxies, LPPI and coprophilous fungi

Micro-Environmental Mechanical Stress Controls Tumor Spheroid Size and Morphology by Suppressing Proliferation and Inducing Apoptosis in Cancer Cells

Compressive mechanical stress produced during growth in a confining matrix limits the size of tumor spheroids, but little is known about the dynamics of stress accumulation, how the stress affects cancer cell phenotype, or the molecular pathways involved.We co-embedded single cancer cells with fluorescent micro-beads in agarose gels and, using confocal microscopy, recorded the 3D distribution of micro-beads surrounding growing spheroids. The change in micro-bead density was then converted to strain in the gel, from which we estimated the spatial distribution of compressive stress around the spheroids. We found a strong correlation between the peri-spheroid solid stress distribution and spheroid shape, a result of the suppression of cell proliferation and induction of apoptotic cell death in regions of high mechanical stress. By compressing spheroids consisting of cancer cells overexpressing anti-apoptotic genes, we demonstrate that mechanical stress-induced apoptosis occurs via the mitochondrial pathway.Our results provide detailed, quantitative insight into the role of micro-environmental mechanical stress in tumor spheroid growth dynamics, and suggest how tumors grow in confined locations where the level of solid stress becomes high. An important implication is that apoptosis via the mitochondrial pathway, induced by compressive stress, may be involved in tumor dormancy, in which tumor growth is held in check by a balance of apoptosis and proliferation

The influence of decision-making in tree ring-based climate reconstructions.

Tree-ring chronologies underpin the majority of annually-resolved reconstructions of Common Era climate. However, they are derived using different datasets and techniques, the ramifications of which have hitherto been little explored. Here, we report the results of a double-blind experiment that yielded 15 Northern Hemisphere summer temperature reconstructions from a common network of regional tree-ring width datasets. Taken together as an ensemble, the Common Era reconstruction mean correlates with instrumental temperatures from 1794-2016 CE at 0.79 (p < 0.001), reveals summer cooling in the years following large volcanic eruptions, and exhibits strong warming since the 1980s. Differing in their mean, variance, amplitude, sensitivity, and persistence, the ensemble members demonstrate the influence of subjectivity in the reconstruction process. We therefore recommend the routine use of ensemble reconstruction approaches to provide a more consensual picture of past climate variability

Multinucleon transfer reactions in closed-shell nuclei

Multinucleon transfer reactions in 40Ca+96Zr and 90Zr+208Pb have been measured at energies close to the Coulomb barrier in a high resolution gamma-particle coincidence experiment. The large solid angle magnetic spectrometer PRISMA coupled to the CLARA gamma-array has been employed. Trajectory reconstruction has been applied for the complete identification of transfer products. Mass and charge yields, total kinetic energy losses, gamma transitions of the binary reaction partners, and comparison of data with semiclassical calculations are reported. Specific transitions in 95Zr populated in one particle transfer channels are discussed in terms of particle-phonon couplings. The gamma decays from states in 42Ca in the excitation energy region expected from pairing vibrations are also observed