Asymptotic Behavior for a Nonlocal Diffusion Equation in Domains with Holes

The paper deals with the asymptotic behavior of solutions to a non-local diffusion equation, $u_t=J*u-u:=Lu$, in an exterior domain, $\Omega$, which excludes one or several holes, and with zero Dirichlet data on $\mathbb{R}^N\setminus\Omega$. When the space dimension is three or more this behavior is given by a multiple of the fundamental solution of the heat equation away from the holes. On the other hand, if the solution is scaled according to its decay factor, close to the holes it behaves like a function that is $L$-harmonic, $Lu=0$, in the exterior domain and vanishes in its complement. The height of such a function at infinity is determined through a matching procedure with the multiple of the fundamental solution of the heat equation representing the outer behavior. The inner and the outer behavior can be presented in a unified way through a suitable global approximation

Boundary fluxes for non-local diffusion

We study a nonlocal diffusion operator in a bounded smooth domain prescribing the flux through the boundary. This problem may be seen as a generalization of the usual Neumann problem for the heat equation. First, we prove existence, uniqueness and a comparison principle. Next, we study the behavior of solutions for some prescribed boundary data including blowing up ones. Finally, we look at a nonlinear flux boundary condition

Rethinking False Spring Risk

Temperate plants are at risk of being exposed to late spring freezes. These freeze events - often called false springs - are one of the strongest factors determining temperate plants species range limits and can impose high ecological and economic damage. As climate change may alter the prevalence and severity of false springs, our ability to forecast such events has become more critical, and it has led to a growing body of research. Many false spring studies largely simplify the myriad complexities involved in assessing false spring risks and damage. While these studies have helped advance the field and may provide useful estimates at large scales, studies at the individual to community levels must integrate more complexity for accurate predictions of plant damage from late spring freezes. Here we review current metrics of false spring, and how, when and where plants are most at risk of freeze damage. We highlight how life stage, functional group, species differences in morphology and phenology, and regional climatic differences contribute to the damage potential of false springs. More studies aimed at understanding relationships among species tolerance and avoidance strategies, climatic regimes, and the environmental cues that underlie spring phenology would improve predictions at all biological levels. An integrated approach to assessing past and future spring freeze damage would provide novel insights into fundamental plant biology, and offer more robust predictions as climate change progresses, which is essential for mitigating the adverse ecological and economic effects of false springs

Magnetic resonance imaging in the prenatal diagnosis of neural tube defects

OBJECTIVE: To assess the role of magnetic resonance imaging (MRI) in the prenatal diagnosis of neural tube defects (NTDs). BACKGROUND: NTDs comprise a heterogeneous group of congenital anomalies that derive from the failure of the neural tube to close. Advances in ultrasonography and MRI have considerably improved the diagnosis and treatment of NTDs both before and after birth. Ultrasonography is the first technique in the morphological study of the fetus, and it often makes it possible to detect or suspect NTDs. Fetal MRI is a complementary technique that makes it possible to clear up uncertain ultrasonographic findings and to detect associated anomalies that might go undetected at ultrasonography. The progressive incorporation of intrauterine treatments makes an accurate diagnosis of NTDs essential to ensure optimal perinatal management. The ability of fetal MRI to detect complex anomalies that affect different organs has been widely reported, and it can be undertaken whenever NTDs are suspected. CONCLUSION: We describe the normal appearance of fetal neural tube on MRI, and we discuss the most common anomalies involving the structures and the role of fetal MRI in their assessment. KEY POINTS: • To learn about the normal anatomy of the neural tube on MRI • To recognise the MR appearance of neural tube defects • To understand the value of MRI in assessing NTD

Hepatoprotection and neuroprotection induced by low doses of IGF-II in aging rats

<p>Abstract</p> <p>Background</p> <p>GH and IGFs serum levels decline with age. Age-related changes appear to be associated to decreases in these anabolic hormones. We have previously demonstrated that IGF-I replacement therapy improves insulin resistance, lipid metabolism and reduces oxidative damage (in brain and liver) in aging rats. Using the same experimental model, the aim of this work was to study whether the exogenous administration of IGF-II, at low doses, acts analogous to IGF-I in aging rats.</p> <p>Methods</p> <p>Three experimental groups were included in this study: young healthy controls (yCO, 17 weeks old); untreated old rats (O, 103 weeks old); and aging rats treated with IGF-II (O+IGF-II, 2 μg * 100 g body weight^-1* day^-1) for 30 days. Analytical parameters were determined in serum by routine laboratory methods using an autoanalyzer (Cobas Mira; Roche Diagnostic System, Basel, Switzerland). Serum levels of hormones (testosterone, IGF-I and insulin) were assessed by RIA. Serum Total Antioxidant Status was evaluated using a colorimetric assay. Mitochondrial membrane potential was evaluated using rhodamine 123 dye (adding different substrates to determine the different states). ATP synthesis in isolated mitochondria was determined by an enzymatic method.</p> <p>Results</p> <p>Compared with young controls, untreated old rats showed a reduction of IGF-I and testosterone levels with a decrease of serum total antioxidant status (TAS). IGF-II therapy improved serum antioxidant capability without modifying testosterone and IGF-I circulating concentrations. In addition, IGF-II treatment reduced oxidative damage in brain and liver, improving antioxidant enzyme activities and mitochondrial function. IGF-II was also able to reduce cholesterol and triglycerides levels increasing free fatty acids concentrations.</p> <p>Conclusions</p> <p>We demonstrate that low doses of IGF-II induce hepatoprotective, neuroprotective and metabolic effects, improving mitochondrial function, without affecting testosterone and IGF-I levels.</p

DEVELOPMENT AND EVALUATION OF THE ATOS SPONTANEOUS SPEECH CONVERSATIONAL SYSTEM

ABSTRACT In this paper we report our recent development work in Spanish spontaneous speech conversational systems. We describe the Automatic Telephone Operator Service (ATOS) and present the improvements introduced into it to deal with spontaneous speech, which are: (a) a task independent dialogue manager, that can be adapted to a new semantic domain by changing a configuration file. It also generates a prediction about the user&apos;s expected utterance to constrain the language model used by the speech recognizer. (b) a language modeling strategy, which allows to adapt the statistical language model to a new task with just few hundreds of sentences. This strategy reduces a 27% the word error rate. We also report the results, conclusions and the speech database collected in the evaluation of the ATOS system, which has been tested by 30 real users

Altered liver gene expression in CCl4-cirrhotic rats is partially normalized by insulin-like growth factor-I

We have previously shown that the administration of low doses of insulin-like growth factor-I (IGF-I) to CCl4-cirrhotic rats improves liver function and reduces fibrosis. To better understand the mechanisms behind the hepatoprotective effects of IGF-I, and to identify those genes whose expression is affected in cirrhosis and after IGF-1 treatment, we have performed differential display of mRNA analysis by means of polymerase chain reaction (PCR) in livers from control and CCl4-cirrhotic rats treated or not with IGF-I. We have identified 16 genes that were up- or down-regulated in the cirrhotic liver. IGF-I treatment partially normalized the expression of eight of these genes, including serine proteinase inhibitors such as serpin-2 and alpha-1-antichymotripsin, alpha-1-acid glycoprotein, and alpha-2u-globulin. Additionally, we show that IGF-I enhanced the regenerative activity in the cirrhotic liver, as determined by the increased expression of the proliferating cell nuclear antigen (PCNA). Finally, IGF-I treatment partially restored the expression of growth hormone receptor (GHR) and the levels of global genomic DNA methylation, which are reduced in human and experimental cirrhosis. Taken together, our observations confirm the hepatoprotective effects of IGF-I, and suggest that this action can be exerted in part through the normalization of liver gene expression, growth hormone (GH) responsiveness and global genomic DNA methylation