Williams College

About: Williams College is a education organization based out in Williamstown, Massachusetts, United States. It is known for research contribution in the topics: Population & Politics. The organization has 2257 authors who have published 5015 publications receiving 213160 citations. The organization is also known as: Williams.

Regulation of IL-4 production in mast cells: a paradigm for cell-type-specific gene expression.

Abstract: The role of interleukin (IL)-4 as an important immunomodulatory cytokine is well established. IL-4 exhibits a highly restricted pattern of expression by cells of distinct lineages. The cell types that produce IL-4 are located in anatomically distinct locations (e.g. circulating T cells vs. fixed tissue mast cells) and thus have access to different IL-4-responsive target cells. In addition, these cells appear to regulate IL-4 expression in cell-type-specific ways. These findings suggest that an understanding of IL-4 gene regulation in T and mast cells could provide the means to specifically control IL-4 release in a lineage- and site-specific manner. In this article we review the current knowledge regarding the cell-type specific regulation of IL-4 gene expression in mast cells and compare this to what has been defined in T cells. We show that there are distinct yet parallel events that control developmentally determined chromatin modifications, allowing accessibility of the locus, and provide the potential for transcription. In differentiated cells, a subset of unique cell activation signals initiates the cascade of events that lead to transcriptional activation of the IL-4 gene.

The accuracy-confidence correlation in eyewitness testimony: limits and extensions of the retrospective self-awareness effect.

Abstract: This research extended Kassin's (1985) finding that retrospective self-awareness (RSA) increases the correlation between eyewitness accuracy and confidence. In Experiment 1, 91 mock witnesses saw a crime, answered questions, made an identification decision, and rated their confidence. RSA increased the accuracy-confidence correlation for witnesses who made an identification and for those who were high but not low in public self-consciousness. A 2nd experiment varied accountability and revealed that high accountability increased the accuracy-confidence correlation but that the RSA effect occurred even under low-accountability conditions. In both studies, observers could not distinguish between accurate and inaccurate witnesses. Together, these findings define the limits of the RSA effect and provide mixed support for a self-perception account of this effect.

Separation of Metallic and Semiconducting Single‐Walled Carbon Nanotube Arrays by “Scotch Tape”

Abstract: Single-walled carbon nanotubes (SWNTs) have been regarded as one of the best candidates for future applications in nanoelectronic devices because of their superb electrical characteristics. However, almost all of the currently available technologies can only produce a mixture of both metallic (m) and semiconducting (s) SWNTs. This coexistence in as-grown samples dramatically decreases the device performance; therefore, SWNTs should be separated before they are integrated into devices. During the past decade, two different approaches have been developed to separate mand sSWNTs. The first approach is selective destruction by, for example, nitronium ion attack, gas-phase etching reactions, weak oxidative carbon sources, and ultraviolet irradiation. The second strategy involves solution-based methods like dielectrophoresis, density-gradient-inducing centrifugation, selective adsorption of chemicals, and agarose-gel-based separation. Both techniques can separate SWNTs effectively, but the former introduces damages to SWNTs, while the latter can only work for very short SWNTs and creates difficulties in the alignment of SWNTs. For the purpose of separation, many efforts have been made to investigate selective interactions between chemicals and SWNTs of different conductivities. Electron donor molecules, such as octadecylamine, have been reported to selectively adsorb to s-SWNTs, while aromatic polymers, such as 9,9-dioctylfluorenyl-2,7-diyl, prefer metallic ones. However, the essential character of these interactions is still unclear. In the case of amines, some researchers think that the interaction is due to the lone pair of the nitrogen atom, while others believe the hydrogen atom is more important. For aromatic polymers, the role of p–p interactions vs. dipole–dipole interactions is controversial. Nevertheless, these adsorption preferences have already been exploited for SWNT separation. Considering the problems associated with separation techniques such as selective destruction and solution-based methods, our goal was to develop a simple way, which is analogous to mechanical exfoliation of graphene using scotch tape to realize SWNT separation. Specifically, we aimed to create “scotch tapes” terminated with various functional groups that could be used to selectively remove either sor mSWNTs and to leave their counterparts on the substrate. Unlike the separation techniques discussed above, this approach was based on the selective adsorption of chemicals to SWNTs of different electrical properties, which can be applied to long SWNTs systems without introducing damage while the SWNTs formation is perfectly maintained. In our experiments, soft polydimethylsiloxane (PDMS) thin films were chosen as the supporting material, while 3aminopropyl-triethoxysilane (C9H23NO3Si, APTES, defined as A-scotch tape) and triethoxyphenylsilane (C12H20O3Si, PTEOS, defined as P-scotch tape) were used as the bonding material to introduce amine and phenyl functional groups, respectively (Figure S1). The Si O Si bonds on the PDMS surface were oxidized to Si OH groups when treated under air plasma. The Si OH groups could be further reacted with APTES/PTEOS to form strong interactions between the supporting PDMS layer and the functionalized bonding layer. SWNT samples with mixtures of mand s-SWNTs could be presynthesized on sapphire substrates. As shown in Figure 1, when the PDMS-based “scotch tapes” were applied to SWNT samples and then peeled off, the A-scotch tape selectively removed s-SWNTs, while the P-scotch tape adhered to metallic ones, leaving their counterparts on the substrate. Single-polished (11–20) plane sapphire substrates (miscut angle < 0.58, surface roughness < 5 ) were purchased from Hefei Kejing Materials Technology Co., China and were used for SWNT growth. After an initial cleaning process, substrates were annealed at 1100 8C for 10 h so that the aligned SWNT arrays could be grown along the 1 100 direction. Growth experiments were performed in a low-pressure chemical vapor deposition (LPCVD) system with a 66 mm quartz tube at a temperature of 850 8C and a pressure of 700 torr. A 3 mm [*] G. Hong, Prof. Dr. Z. F. Liu, Prof. Dr. J. Zhang Center for Nanochemistry, Beijing National Laboratory for Molecular Sciences, Key Laboratory for the Physics and Chemistry of Nanodevices, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University Beijing 100871 (China) Fax: (+ 86)10-6275-7157 E-mail: jinzhang@pku.edu.cn

The full expression of fasting-induced torpor requires beta 3-adrenergic receptor signaling.

Abstract: Torpor, a controlled rapid drop in metabolic rate and body temperature (Tb), is a hypometabolic adaptation to stressful environmental conditions, which occurs in many small mammals, marsupials, and birds. To date, signaling pathways required for torpor have not been identified. We examined the role of the sympathetic nervous system (SNS) in mediating the torpor adaptation to fasting by telemetrically monitoring the Tb of dopamine beta-hydroxylase knock-out (Dbh-/-) mice, which lack the ability to produce the SNS transmitters, norepinephrine (NE), and epinephrine. Control (Dbh+/-) mice readily reduced serum leptin levels and entered torpor after a fast in a cool environment. In contrast, Dbh-/- mice failed to reduce serum leptin and enter torpor under fasting conditions, whereas restoration of peripheral but not central NE lowered serum leptin levels and rescued the torpor response. Torpor was expressed in fasted Dbh-/- mice immediately after administration of either the nonselective beta-adrenergic receptor agonist isoproterenol or the beta3-adrenergic receptor (AR)-specific agonist CL 316243 [disodium (RR)-5-[2-[[2-(3-chlorophenyl)-2-hydroxyethyl]-amino]propyl]-1,3-benzodioxazole-2,2-dicarboxylate], but not after administration of beta1, beta2, or alpha1 agonists. Importantly, the beta3-specific antagonist SR 59230A [3-(2-ethylphenoxy)-1-[(1,S)-1,2,3,4-tetrahydronapth-1-ylamino]-2S-2-propanol oxalate] severely blunted fasting-induced torpor in control mice, whereas other AR antagonists were ineffective. These results define a critical role of peripheral SNS activity at beta3-AR-containing tissues in the torpor adaptation to limited energy availability and cool ambient temperature.

Preschool antecedents of defense mechanism use in young adults: a longitudinal study.

Abstract: Preschool antecedents of the use of defense mechanisms were longitudinally studied using data from 90 nursery school children who were again evaluated at age 23. Defense use was determined by coding Thematic Apperception Test (H.A. Murray, 1943) stories with a method previously shown to be reliable and valid. The findings indicated continuity between preschool personality and subsequent defense use for male participants but little continuity for female participants. Young men's use of the age-inappropriate defense of denial was predicted by indications at ages 3-4 of low ego resiliency and psychological difficulties in the areas of emotion, intellect, impulse control, and social interactions.