Towards a Geometric Approach to Strassen's Asymptotic Rank Conjecture

We make a first geometric study of three varieties in $\mathbb{C}^m \otimes \mathbb{C}^m \otimes \mathbb{C}^m$ (for each $m$), including the Zariski closure of the set of tight tensors, the tensors with continuous regular symmetry. Our motivation is to develop a geometric framework for Strassen's Asymptotic Rank Conjecture that the asymptotic rank of any tight tensor is minimal. In particular, we determine the dimension of the set of tight tensors. We prove that this dimension equals the dimension of the set of oblique tensors, a less restrictive class introduced by Strassen.Comment: Final version. Revisions in Section 1 and Section

Diabetic pregnancy outcome in Malta the outcome of non-gestational diabetic pregnancies in the Maltese Islands

Diabetes in pregnancy is generally associated with a higher morbidity and mortality for both the mother and child. Objective: The study aims to assess the outcome indicators of diabetic pregnant women and compare these to the remaining obstetric population. Research Design and Methods: Women diagnosed as suffering from diabetes prior to their pregnancy were identified (n = 44) and their outcome indicators were compared to the parameters of the women with a presumed normal carbohydrate metabolism (n = 12260). Women diagnosed with gestational DM (defined as a 2-hour post-load blood glucose of >=8.6 mmol/l: n=236) were excluded from the analysis. Results: The incidence of pre-existing diabetic problems in the Maltese pregnant population is 0.35% of total maternities. Women with pre-existing DM showed themselves to be at a significantly increased risk of developing hypertensive disorders during pregnancy and to require delivery by caesarean section. The infants born to pre-existing DM women were more likely to be macrosomic or preterm and have a low Apgar score at birth. They were also more likely to be of low birth weight and suffer from respiratory distress. Conclusions: It would appear that previously existing diabetes complicating pregnancy remains a high risk situation that increases maternal and infant morbidity in spite of the modern management options.peer-reviewe

The outcome of Gestational Diabetic pregnancies in the Maltese Islands

Gestational diabetes is generally associated with a higher morbidity and mortality for both the mother and child. Aims: The study aims to assess the outcome indicators of women suffering gestational diabetes and compare these to the remaining obstetric population. Research Design and Methods: Outcome indicators of women diagnosed during pregnancy as suffering from diabetes (GDM (defined as a 2-hour post-load blood glucose of >=8.6 mmol/l) n=297) were compared to the parameters of women with a presumed normal carbohydrate metabolism (n = 16059). Results: The incidence of gestational diabetes in the Maltese pregnant population is 1.81 % of total maternities. Women with GDM showed themselves to be at a significantly increased risk of developing hypertensive disorders during pregnancy and to require delivery by caesarean section. They were more likely to require intervention by induction of labour, while the delivery was commonly complicated by shoulder dystocia. The infants born to GDM women were more likely to be macrosomic or preterm and have a low Apgar score at birth and suffer from respiratory distress. The infants did not show a greater predisposition to be of low birth weight. Conclusion: It would appear that gestational diabetes remains a high-risk situation that increases maternal and infant morbidity in spite of the modern management options.peer-reviewe

Mother–infant Interactions and Infant Intake during Breastfeeding Versus Bottle-feeding Expressed Breast Milk

Bottle-fed infants are at higher risk for rapid weight gain compared with breastfed infants. Few studies have attempted to disentangle effects of feeding mode, milk composition and relevant covariates on feeding interactions and outcomes. The objective of the present study was to compare effects of breastfeeding directly at the breast versus bottle-feeding expressed breast milk on feeding interactions. Mothers with \u3c6-month-old infants (n = 47) participated in two counterbalanced, feeding observations. Mothers breastfed their infants directly from the breast during one visit (breast condition) and bottle-fed their infants expressed breast milk during the other (bottle condition). Masked raters later coded videos using the Nursing Child Assessment Parent–Child Interaction Feeding Scale. Infant intake was assessed. Mothers self-reported sociodemographic characteristics, infant feeding patterns (i.e. percentage of daily feedings from bottles) and level of pressuring feeding style. Mother and infant behaviours were similar during breast and bottle conditions. Percent bottle-feeding moderated effects of condition on intake (P = 0.032): greater percent bottle-feeding predicted greater intake during the bottle compared with breast condition. Effects of feeding mode were not moderated by parity or pressuring feeding style, but, regardless of condition, multiparous mothers fed their infants more than primiparous mothers (P = 0.028), and pressuring feeding style was positively associated with infant intake (P = 0.045). Findings from the present study do not support the hypothesis that feeding mode directly impacts dyadic interaction for predominantly breastfeeding mothers and infants, but rather suggest between-subject differences in feeding experiences and styles predict feeding outcomes for this population

Connectivity-enhanced diffusion analysis reveals white matter density disruptions in first episode and chronic schizophrenia.

Reduced fractional anisotropy (FA) is a well-established correlate of schizophrenia, but it remains unclear whether these tensor-based differences are the result of axon damage and/or organizational changes and whether the changes are progressive in the adult course of illness. Diffusion MRI data were collected in 81 schizophrenia patients (54 first episode and 27 chronic) and 64 controls. Analysis of FA was combined with "fixel-based" analysis, the latter of which leverages connectivity and crossing-fiber information to assess both fiber bundle density and organizational complexity (i.e., presence and magnitude of off-axis diffusion signal). Compared with controls, patients with schizophrenia displayed clusters of significantly lower FA in the bilateral frontal lobes, right dorsal centrum semiovale, and the left anterior limb of the internal capsule. All FA-based group differences overlapped substantially with regions containing complex fiber architecture. FA within these clusters was positively correlated with principal axis fiber density, but inversely correlated with both secondary/tertiary axis fiber density and voxel-wise fiber complexity. Crossing fiber complexity had the strongest (inverse) association with FA (r = -0.82). When crossing fiber structure was modeled in the MRtrix fixel-based analysis pipeline, patients exhibited significantly lower fiber density compared to controls in the dorsal and posterior corpus callosum (central, postcentral, and forceps major). Findings of lower FA in patients with schizophrenia likely reflect two inversely related signals: reduced density of principal axis fiber tracts and increased off-axis diffusion sources. Whereas the former confirms at least some regions where myelin and or/axon count are lower in schizophrenia, the latter indicates that the FA signal from principal axis fiber coherence is broadly contaminated by macrostructural complexity, and therefore does not necessarily reflect microstructural group differences. These results underline the need to move beyond tensor-based models in favor of acquisition and analysis techniques that can help disambiguate different sources of white matter disruptions associated with schizophrenia

Comportamiento mecánico de un concreto adicionando fibra de acero dramix 4d como alternativa de solución en pavimentos rígidos

Actualmente se busca mejorar las características del concreto, el uso de fibra de acero puede incrementar la resistencia y disminuir las fisuras. El objetivo de esta investigación es evaluar la caracterización mecánica del concreto adicionando el 0.5%, 1%, 1.5%, 2% e If-min (indicación mínima del fabricante) de fibra de acero Dramix 4D 80/60 BG y 65/60 BG en un concreto f'c de 280 kg/cm², para ser ensayados a los 7, 14 y 28 días de curado, para analizar su comportamiento mecánico. La metodología utilizada es de tipo aplicada bajo un diseño experimental. Los resultadosde acuerdo a las fibras de acero Dramix 4D, se tiene dos tipos; la primera Dramix 4D 80/60BG, y la segunda es Dramix 4D 65/60BG, para ambas se obtuvo el porcentaje óptimo dando como resultado el 2.0%. De acuerdo para un diseño de f’c= 280 kg/cm²a las fibras de Dramix 4D 80/60BG, aumentó la resistencia a la compresión en un 4.04%, en la resistencia a la flexión aumentó en un 22.31 % y la resistencia a la tracción aumentó un 32.58%. Mientras que las fibras de acero Dramix 4D 65/60BG, aumentó la resistencia a la compresión en un 9.53% y en la resistencia a la flexión aumentó en un 38.48 % y la resistencia a la tracción aumentó un 61.35%. Es por ello se concluye que ambas fibras, desde la dosificación mínima recomendadas por el fabricante se obtienen buenos resultados, demostrando que las fibras son eficaces para reducir grietas o fracturas en el concreto para pavimentos rígidosTesisInfraestructura, Tecnología y Medio Ambient

Differences of temporal dynamics and signal complexity of gamma band oscillations in first-episode psychosis during a working memory task

Gamma band oscillations participate in the temporal binding needed to synchronize cortical networks, involved in early sensory and short term memory processes. In earlier studies, alterations of these neurophysiological parameters have been found in psychotic disorders. To date no study has explored the temporal dynamics and signal complexity of gamma band oscillations in first episode psychosis (FEP). To address this issue, gamma band analysis was performed in 15 FEP patients and 18 healthy controls who successfully performed an adapted 2-back working memory task. Multiple linear and logistic regression models were computed to explore the relationship between the cognitive status and gamma oscillation changes over time. Based on regression model results, phase diagrams were constructed and their complexity was estimated using fractal dimension, a mathematical tool that describes shapes as numeric values. When adjusted for gamma values at time lags −3 to −4 ms and −15 to −16 ms, FEP patients displayed significantly higher time-dependent changes than controls, independently of the nature of the task. The present results are consistent with a discoordination of the activity of cortical generators engaged by the stimulus apparition in FEP patients, leading to a global binding deficit. In addition, fractal analysis showing higher complexity of gamma signal, confirmed this deficit. Our results provide evidence for recruitment of supplementary cortical generators as compensating mechanisms and yield further understanding for the pathophysiology cognitive impairments in FEP