Doped Semiconductor Devices for sub-MeV Dark Matter Detection

Dopant atoms in semiconductors can be ionized with $\sim10$ meV energy depositions, allowing for the design of low-threshold detectors. We propose using doped semiconductor targets to search for sub-MeV dark matter scattering or sub-eV dark matter absorption on electrons. Currently unconstrained cross sections could be tested with a 1 g-day exposure in a doped detector with backgrounds at the level of existing pure semiconductor detectors, but improvements would be needed to probe the freeze-in target. We discuss the corresponding technological requirements and lay out a possible detector design.Comment: 12 pages, 7 figure

Altered cortical development in fetuses with isolated nonsevere ventriculomegaly assessed by neurosonography

OBJECTIVES: To perform a comprehensive assessment of cortical development in fetuses with isolated nonsevere ventriculomegaly (INSVM) by neurosonography. METHODS: We prospectively included 40 fetuses with INSVM and 40 controls. INSVM was defined as atrial width between 10.0 and 14.9 mm without associated malformation, infection, or chromosomal abnormality. Cortical development was assessed by neurosonography at 26 and 30 weeks of gestation measuring depth of selected sulci and applying a maturation scale from 0 (no appearance) to 5 (maximally developed) of main sulci and areas. RESULTS: INSVM showed underdeveloped calcarine and parieto-occipital sulci. In addition, significant delayed maturation pattern was also observed in regions distant to ventricular system including Insula depth (controls 30.8 mm [SD 1.7] vs INSVM 31.7 mm [1.8]; P = .04), Sylvian fissure grading (>2 at 26 weeks: controls 87.5% vs INSVM 50%, P = .01), mesial area grading (>2 at 30 weeks: controls 95% vs INSVM 62.5%; P = .03), and cingulate sulcus grading (>2 at 30 weeks: controls 100% vs INSVM 80.5%; P = .01). CONCLUSIONS: Fetuses with INSVM showed underdeveloped cortical maturation including also regions, where effect of ventricular dilatation is unlikely. These results suggest that in a proportion of fetuses with INSVM, ventricular dilation might be related with altered cortical architecture

Role of uteroplacental and fetal Doppler in identifying fetal growth restriction at term.

Identification of the fetus at risk of adverse outcome at term is a challenge to both clinicians and researchers alike. Despite the fact that fetal growth restriction (FGR) is a known risk factor for stillbirth, at least two thirds of the stillbirth cases at term are not small for gestational age (SGA) - a commonly used proxy for FGR. However, the majority of SGA fetuses are constitutionally small babies and do not suffer from adverse perinatal outcome. The cerebroplacental ratio (CPR) is emerging as a marker of failure to reach growth potential at term. CPR is an independent predictor of intrapartum fetal distress, admission to the neonatal unit at term, stillbirth, perinatal death and neonatal morbidity. Raised uterine artery Doppler resistance in the third trimester is independently associated with significantly lower birthweight and CPR. The combination of the estimated fetal weight, CPR and uterine Doppler in the third trimester can identify the majority of fetuses at risk of stillbirth

Neuroimaging assessment of Cortical Development and Corpus Callosum as predictive markers of neurodevelopmental outcome in small for gestational age fetuses

[spa] “EVALUACIÓN DEL DESARROLLO CORTICAL Y CUERPO CALLOSO COMO MARCADORES PREDICTIVOS DE NEURODESARROLLO EN FETOS PEQUEÑOS PARA LA EDAD GESTACIONAL “ INTRODUCCION: la restricción del crecimiento intrauterino (RCIU) afecta alrededor del 8% de los recién nacidos vivos y se asocia a morbilidad a corto y a largo plazo, dentro de los cuales se encuentran los déficits neurológicos. Nuestra hipótesis es que dichos déficits se asocian a una reprogramación cerebral durante la vida intrauterina gatillada por la RCIU. Por lo que el objetivo de esta tesis fue detectar biomarcadores cerebrales que puedan predecir un resultado neurológico adverso en los fetos con RCIU. MÉTODOS: incluimos dos grupos de estudio: AGA (fetos adecuados para la edad gestacional) y SGA (fetos pequeños para la edad gestacional definidos por un percentil de crecimiento[eng] 1. INTRODUCTION Intrauterine growth restriction (IUGR) is diagnosed at the presence of an estimated fetal weight below the 10th centile and is a frequent condition in perinatal medicine, reaching a prevalence of 5-8% in live newborn babies being a major contributor of perinatal and long term morbidity, such as neurological deficits. We hypothesized that these neurological impairement are related to brain microstructural changes which might be characterized by fetal neuroimaging, either MRI or ultrasonography. Identifying fetuses at risk for abnormal neurodevelopment in fetal medicine lays the basis to perform specific strategies to potentially improve both pre and postnatal management, such as timely delivery, careful support for breastfeeding and a thoughtful use of this window of opportunity to improve their neurocognitive outcome through specific strategies. So the objective of this thesis was to identify brain imaging biomarkers that could predict an adverse neurological outcome in small for gestational age fetuses. 2. METHODS This is a prospective cohort study which included 2 study groups: AGA (adequeate for gestational age fetuses) with an estimated fetal weight >10th centile and, SGA (small for gestational age fetuses) with an estimated fetal weight <10th centile. A fetal ultrasound was performed to establish clinical group membership and Doppler evaluation. Then, either a MRI at 37 weeks was performed or a neurosonography during the 3rd trimester in order to assess cortical development, insular and corpus callosum morphometry. Once these babies were born, they underwent a neurobehavioral assessment during the neonatal period (NBAS) and a neurodevelopmental test at 2 years (Bayley-III). The analysis was focused on the evaluation of differences among study groups. As secondary analysis, linear regression was used to evaluate the relationship between brain development and postnatal neurological outcome adjusting by potentially confounders. Statistical anlyses were performed using the SPSS for Windows version 17.0 statistical software. 3. RESULTS The thesis led to five articles which are published in international journals. Maternal characteristics did not differ between the study groups. We found that late-onset IUGR fetuses showed a different pattern of brain development assessed by fetal MRI, expressed by deeper fissures, smaller brain volumes and a more pronounced right asymmetry. They also presented thinner cortex with lower fractional anisotropy values wich was significantly associated to worse NBAS test. Small fetuses presented smaller corpus callosum assessed by MRI and US, particularly in its posterior portion which was associated to worse neurobehavioral outcome. When we explored the correlation between brain structure and neurodevelopment at 2 years, we found that smaller measurements were associated to worse Bayley-III scores. 7. DISCUSSION Although previous studies have shown poorer neurodevelopmental outcome in term, none of them have provided information about their brain developmental status before birth. Our findings support a microstructural/functional association. Interestingly, we found that small-born babies had lower cognitive, motor and language competencies. All of these functions are closely related to the insula and callosal functionality. Indeed, Geva et al. proposed that thinner cortex found in severe IUGR born children could be responsible for their lower IQ scores. The importance of this study relais in the high prevalence of late-onset IUGR, therefore they represent a significant public health problem and its impact on the adverse neurodevelopment outcome of this population cannot be overestimated. Therefore findings applicable imaging biomarkers in fetal medicine can identify those fetuses at risk in this and other clinical scenarios. Finally, our study suggests that brain alterations at term could constitute the first step in the cascade of functional impairments underlying neurodevelopmental pathologies

Frequency of differential placental transfer to twins of maternal antiretroviral medications

International audienceBackground: Placental passage of drugs in twins is poorly understood, and is unknown regarding antiretrovirals (ARVs). In the event of large differences in the exposure of 2 twins to the same maternal therapy, this could have a clinical impact in terms of prevention of perinatal HIV transmission or adverse effects.Objective: To describe the frequency of differential transplacental passage of antiretrovirals between twins.Study design: The study was performed retrospectively, on data from women included in a multicenter perinatal HIV cohort study. All twin pairs for which the mother received antiretroviral therapy and for which drug concentrations in both of the umbilical cords after cord clamping at delivery were studied. We considered that a difference in concentrations of more than 50 % between twins was a substantial difference (ratios below 0.67 or above 1.50).Results: We analyzed 29 twin pairs, 27 dichorionic and 2 monochorionic diamniotic. Cord blood concentrations differed between the 2 twins by more than 50 % for at least one ARV in 9 twin pairs, 8 dichorionic and 1 monochorionic. Discordant concentrations were observed in one or more cases for several nucleoside reverse transcriptase inhibitors (tenofovir, emtricitabine, lamivudine, zidovudine) and protease inhibitors (atazanavir, lopinavir, saquinavir et ritonavir); within individual twin pairs placental transfer was discordant for one or more ARVs, but identical for others.Conclusion: Concentrations differed in nearly one third of twin pairs. This may be due to interindividual genetic variability of placental transporters between dizygotic twins as well as physiological differences between twins