194 research outputs found
Equivalent birational embeddings II: divisors
Two divisors in are said to be Cremona equivalent if there is a
Cremona modification sending one to the other. We produce infinitely many non
equivalent divisorial embeddings of any variety of dimension at most 14. Then
we study the special case of plane curves and rational hypersurfaces. For the
latter we characterise surfaces Cremona equivalent to a plane.Comment: v2 Exposition improved, thanks to referee, unconditional
characterization of surfaces Cremona equivalent to a plan
Insulin-secreting pituitary GH3 cells : a potential beta-cell surrogate for diabetes cell therapy
In a companion article, we describe the engineering and characterization of pituitary GH3 cell clones stably transfected with a furin-cleavable human insulin cDNA (InsGH3 cells). This article describes the performance of InsGH3 (clones 1 and 7) cell grafts into streptozotocin (STZ)-induced diabetic nude mice. Subcutaneous implantation of 2
7 106 InsGH3 cells resulted in the progressive reversal of hyperglycemia and diabetic symptoms, even though the progressive growth of the transplanted cells (clone 7) eventually led to glycemic levels below the normal mouse range. Proinsulin transgene expression was maintained in harvested InsGH3 grafts that, conversely, lose the expression of the prolactin (PRL) gene. Elevated concentrations of circulating mature human insulin were detected in graft recipients, demonstrating that proinsulin processing by InsGH3 cells did occur in vivo. Histologic analysis showed that transplanted InsGH3 grew in forms of encapsulated tumors composed of cells with small cytoplasms weakly stained for the presence of insulin. Conversely, intense insulin immunoreactivity was detected in graft-draining venules. Compared to pancreatic \u3b2TC3 cells, InsGH3 cells showed in vitro a higher rate of replication, an elevate resistance to apoptosis induced by serum deprivation and proinflammatory cytokines and significantly higher antiapoptotic Bcl-2 protein levels. Moreover, InsGH3 cells were resistant to the streptozotocin toxicity that, in contrast, reduced \u3b2TC3 cell viability to 50-60% of controls. In conclusion, proinsulin gene expression and mature insulin secretion persisted in transplanted InsGH3 cells that reversed hyperglycemia in vivo. InsGH3 cells might represent a potential \u3b2-cell surrogate because they are more resistant than pancreatic \u3b2 cells to different apoptotic insults and might therefore be particularly suitable for encapsulation
Combining experiences of race gaming and natural driving affects gaze location strategy in simulated context
Adverse effects of anxiety on attentional control differ as a function of experience: A simulated driving study
This study tested whether adverse effects of state anxiety on attention and performance may be modulated by experience. Sixteen experienced and eleven inexperienced drivers drove in a simulator under low- and high-stress conditions. Anxiety was manipulated by competition, the presence of an evaluator, external video camera, and traffic noise. Most drivers showed greater anxiety scores and higher mean heart rates following manipulation. In both groups increased state anxiety decreased car speed control and caused more collisions, accompanied by fewer fixations of longer duration towards the driving lane across a horizontally narrower region. Inexperienced drivers increased the number of short fixations towards cars, while experienced drivers increased the number of short fixations on the speedometer. Although anxiety impairs processing efficiency and performance effectiveness for both groups, attentional changes differ as a function of experience. Inexperienced drivers tended to shift attention to threatening stimuli, while experienced drives were more likely to consciously monitor task goal
Racing videogame playersâ driving experience in natural context does not affect gaze strategy towards tangent point during simulated curve negotiation, but the curvature angle does
The influence of anxiety on visual entropy of experienced drivers
This study tested the use of entropy to identify changes on behavior of drivers under pressure. Sixteen experienced drivers drove in a simulator wearing a head-mounted eye tracker under low- and high-anxiety conditions. Anxiety was induced by manipulating some psychological factors such as peer-pressure. Fixations transitions between AOIs (lane, speedometer and mirrors) were calculated through first-order transition matrix, transformed to Markov probability matrix and adjusted into the entropy equation. Drivers showed greater state-anxiety scores and higher mean heart rates following manipulation. Under anxiety, drivers showed higher visual entropy, indicating a more random scanning. The randomness implies into a poorer acquisition of information and may indicate an impaired top-down control of attention provoked by anxiety
Stage 4 neuroblastoma: sequential hemi-body irradiation or high-dose chemotherapy plus autologous haemopoietic stem cell transplantation to consolidate primary treatment
The aim of the present study was to evaluate the effectiveness of two consecutive nonrandomised treatment programs applied between 1989 and 1999 at the Istituto Nazionale Tumori of Milan in an unselected cohort of 59 children over the age of one with stage 4 neuroblastoma. Both treatment programs consisted of two phases, the induction of the remission phase and the consolidation phase. The induction of the remission phase consisted of intensive chemotherapy, and remained the same throughout the study period. The consolidation phase consisted of sequential hemi-body irradiation (HBI) (10âGy per session, 6 weeks apart) in the first period (1988âJune 1994) and sequential high-dose cyclophosphamide, etoposide, mitoxantrone+L-PAM and autologous haemopoietic stem cell transplantation in the second (July 1994â1999). Intention-to-treat analysis revealed a significantly better outcome for patients treated with the second program, the 5-year event-free survival probability being 0.12 for program 1 and 0.31 for program 2 (P=0.03). This finding led us to conclude that sequential HBI is useless as consolidation treatment. The high-dose chemotherapy adopted in the second program enabled a proportion of patients to obtain long-term survival but, since the clinical results remain unsatisfactory, new treatment strategies are warranted
Proinflammatory Cytokines Activate the Intrinsic Apoptotic Pathway in ÎČ-Cells
OBJECTIVE:Proinflammatory cytokines are cytotoxic to beta-cells and have been implicated in the pathogenesis of type 1 diabetes and islet graft failure. The importance of the intrinsic mitochondrial apoptotic pathway in cytokine-induced beta-cell death is unclear. Here, cytokine activation of the intrinsic apoptotic pathway and the role of the two proapoptotic Bcl-2 proteins, Bad and Bax, were examined in beta-cells.RESEARCH DESIGN AND METHODS:Human and rat islets and INS-1 cells were exposed to a combination of proinflammatory cytokines (interleukin-1beta, interferon-gamma, and/or tumor necrosis factor-alpha). Activation of Bad was determined by Ser136 dephosphorylation, mitochondrial stress by changes in mitochondrial metabolic activity and cytochrome c release, downstream apoptotic signaling by activation of caspase-9 and -3, and DNA fragmentation. The inhibitors FK506 and V5 were used to investigate the role of Bad and Bax activation, respectively. [...
Planck intermediate results. XLIX. Parity-violation constraints from polarization data
Parity-violating extensions of the standard electromagnetic theory cause in vacuo rotation of the plane of polarization of propagating photons. This effect, also known as cosmic birefringence, has an impact on the cosmic microwave background (CMB) anisotropy angular power spectra, producing non-vanishing TâB and EâB correlations that are otherwise null when parity is a symmetry. Here we present new constraints on an isotropic rotation, parametrized by the angle α, derived from Planck 2015 CMB polarization data. To increase the robustness of our analyses, we employ two complementary approaches, in harmonic space and in map space, the latter based on a peak stacking technique. The two approaches provide estimates for α that are in agreement within statistical uncertainties and are very stable against several consistency tests.Considering the TâB and EâB information jointly, we find from the harmonic analysis and from the stacking approach. These constraints are compatible with no parity violation and are dominated by the systematic uncertainty in the orientation of Planckâs polarization-sensitive bolometers
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