Brown University

About: Brown University is a education organization based out in Providence, Rhode Island, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 35778 authors who have published 90896 publications receiving 4471489 citations. The organization is also known as: brown.edu & Brown.

Bidirectional long-term modification of synaptic effectiveness in the adult and immature hippocampus.

Abstract: Previously we showed that delivering 900 pulses to the Schaffer collateral-CA1 pathway at 1-3 Hz causes a lasting depression of synaptic effectiveness that is input specific and dependent on NMDA receptor activation (Dudek and Bear, 1992a). Here we describe experiments aimed at further characterizing this homosynaptic long-term depression (LTD) and comparing it with long-term potentiation (LTP). To address the question of whether depressed synapses can still be potentiated and vice versa, LTP was saturated with repeated high-frequency tetani, and then LTD was induced with low-frequency stimulation (LFS). A second strong tetanus then restored the potentiation, indicating that the same synapses whose transmission had been depressed by LFS were capable of subsequently supporting potentiation. In a complementary experiment, LTD was induced first and then a strong high-frequency tetanus was delivered. We found that the resulting LTP achieved the same absolute magnitude as that observed in control slices that had received the high-frequency stimulation alone. Next, the postnatal development of LTD was investigated in slices prepared from rats at 6-35 d of age. The consequences of LFS were far more pronounced in slices from young rats. LTD following 900 pulses at 1 Hz measured -45 +/- 4% in CA1 of rats less than 2 weeks old as compared with -20 +/- 4 in animals at 5 weeks postnatal. It was also found that LTD precedes the developmental onset of LTP in CA1. Finally, we addressed the question of whether LTD could be saturated by repeated episodes of LFS in slices prepared from 3-week-old rats.(ABSTRACT TRUNCATED AT 250 WORDS)

SFARI Gene 2.0: a community-driven knowledgebase for the autism spectrum disorders (ASDs)

Abstract: New technologies enabling genome-wide interrogation have led to a large and rapidly growing number of autism spectrum disorder (ASD) candidate genes. Although encouraging, the volume and complexity of these data make it challenging for scientists, particularly non-geneticists, to comprehensively evaluate available evidence for individual genes. Described here is the Gene Scoring module within SFARI Gene 2.0 (https://gene.sfari.org/autdb/GS_Home.do), a platform developed to enable systematic community driven assessment of genetic evidence for individual genes with regard to ASD.

Trends in Care Practices, Morbidity, and Mortality of Extremely Preterm Neonates, 1993-2012

Abstract: Obstet Gynecol Surv 2016;71(1):7–9Since the 1990s, there have been considerable changes in care for mothers in preterm labor and for extremely preterm infants. The Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network has monitored changes in this

Tuning the Electronic Properties of Semi- conducting Transition Metal Dichalco- genides by Applying Mechanical Strains

Abstract: Semiconducting transitionmetaldichalcogenides (TMDs) are emerging as the potential alternatives to gra- phene. As in the case of gra- phene, the monolayer of TMDs can easily be exfoliated using me- chanical or chemical methods, and their properties can also be tuned. At the same time, semiconducting TMDs(MX2;M=Mo,WandX=S, Se, Te) possess an advantage over grapheneinthattheyexhibitabandgapwhosemagnitudeisappropriateforapplicationsintheopto- electronicdevices.Usingabinitiosimulations,wedemonstratethatthisbandgapcanbewidelytuned by applyingmechanicalstrains.While theelectronic propertiesof grapheneremain almost unaffected by tensile strains, we find TMDs to be sensitive to both tensile and shear strains. Moreover, compared to that of graphene, a much smaller amount of strain is required to vary the band gap of TMDs. Our results suggest that mechanical strains reduce the band gap of semiconducting TMDs causing an direct-to-indirect band gap and a semiconductor-t o-metal transition. These transitions, however, significantly depend on the type of applied strain and the type of chalcogenide atoms. The diffuse nature of heavier chalcogenides require relatively more tensile and less shear strain (when the monolayerisexpandediny-directionandcompressedinx-direction) toattainadirect-to-indirectband gap transition. In addition, our results demonstrate that the homogeneous biaxial tensile strain of around 10% leads to semiconductor-to-metal transition in all semiconducting TMDs, while through pureshearstrainthistransitioncanonlybeachievedbyexpandingandcompressingthemonolayerof MTe2in the y-andx-directions, respectively. Our results highlight the importance of tensile and pure shear strains in tuning the electronic properties of TMDs by illustrating a substantial impact of the strain on going from MS2 to MSe2 to MTe2.