Synthesis and analysis of elastic high-speed cam-operated mechanisms

In the synthesis of high-speed cam profiles, we must compensate for the elastic deflections induced by large inertial effects generated during operation. Thus, differential equations with kinematic constraints need to be solved. The governing dynamic equations are in homogeneous, periodic, linear, ordinary differential equations which possess multiple unstable and high vibrational regions at various operating speed zones. These regions are found to be intrinsically determined by the changing geometry of the follower linkage during operation;This dissertation considers two types of cam driven linkages. Parts I and II consider a cam driving a lumped inertia through a massless elastic slider-crank follower linkage with concentrated masses located at two of the joints. The output shaft and the links are subject to torsional and axial deflection, respectively. Part III considers a cam driving a lumped mass through an elastic slider-crank follower linkage with a curved beam coupler. The coupler is modeled using finite element techniques, and the output shaft is subject to torsion only;In both Parts I and III an iterative procedure, taking the elasticity, damping, and changing geometry of the linkage into account, is developed for synthesizing the cam profile to produce a desired output motion at a given design speed. The response improves as iteration proceeds. The number of iteration is limited by the numerical truncation because the value of a parameter decreases at each iteration. The iterative procedure lowers all the high amplitude vibrations in Part I and some of the high amplitude vibrations in Part III;In Part II the location of a single dominant pair of complex characteristic multipliers on the complex plane is used to explain the formation of high amplitude vibrations at certain speeds. These multipliers, which are eigenvalues of the discrete transition matrix for a complete cycle of operation, also predict the effects of inaccurate damping ratio estimates;For either type of linkage considered, design speeds should not be chosen close to the intrinsically high vibration speeds which can be found through simulation of the initial trial design

Revealing the binary origin of Type Ic superluminous supernovae through nebular hydrogen emission

We propose that nebular H-alpha emission as detected in the Type Ic superluminous supernova iPTF13ehe stems from matter which is stripped from a companion star when the supernova ejecta collide with it. The temporal evolution, the line broadening, and the overall blueshift of the emission are consistent with this interpretation. We scale the nebular H-alpha luminosity predicted for Type Ia supernovae in single-degenerate systems to derive the stripped mass required to explain the H-alpha luminosity of iPTF13ehe. We find a stripped mass of 0.1 - 0.9 solar masses, assuming that the supernova luminosity is powered by radioactivity or magnetar spin down. Because a central heating source is required to excite the H-alpha emission, an interaction-powered model is not favored for iPTF13ehe if the H-alpha emission is from stripped matter. We derive a companion mass of more than 20 solar masses and a binary separation of less than about 20 companion radii based on the stripping efficiency during the collision, indicating that the supernova progenitor and the companion formed a massive close binary system. If Type Ic superluminous supernovae generally occur in massive close binary systems, the early brightening observed previously in several Type Ic superluminous supernovae may also be due to the collision with a close companion. Observations of nebular hydrogen emission in future Type Ic superluminous supernovae will enable us to test this interpretation.Comment: 4 pages, 1 figure, 1 table, accepted by Astronomy & Astrophysics Letter

Recombineering strategies for developing next generation BAC transgenic tools for optogenetics and beyond

The development and application of diverse BAC transgenic rodent lines has enabled rapid progress for precise molecular targeting of genetically-defined cell types in the mammalian central nervous system. These transgenic tools have played a central role in the optogenetic revolution in neuroscience. Indeed, an overwhelming proportion of studies in this field have made use of BAC transgenic Cre driver lines to achieve targeted expression of optogenetic probes in the brain. In addition, several BAC transgenic mouse lines have been established for direct cell-type specific expression of Channelrhodopsin-2 (ChR2). While the benefits of these new tools largely outweigh any accompanying challenges, many available BAC transgenic lines may suffer from confounds due in part to increased gene dosage of one or more “extra” genes contained within the large BAC DNA sequences. Here we discuss this under-appreciated issue and propose strategies for developing the next generation of BAC transgenic lines that are devoid of extra genes. Furthermore, we provide evidence that these strategies are simple, reproducible, and do not disrupt the intended cell-type specific transgene expression patterns for several distinct BAC clones. These strategies may be widely implemented for improved BAC transgenesis across diverse disciplines.Brain and Behavior Research Foundation (Young Investigator Award)National Institutes of Health (U.S.). Ruth L. Kirschstein National Research Service Award (F32-MH084460

An Archaeometallurgical Explanation for the Disappearance of Egyptian and Near Eastern Cobalt-Blue Glass at the end of the Late Bronze Age

A recent compositional study of Egyptian cobalt-blue glass from museum collections in Japan (18th Dynasty) and from the site of Dahshur (18th and 19th-20th Dynasties) concluded that a new source of cobalt was exploited for the later Dahshur glass, thereby suggesting that glass production continued into the Ramesside period (Abe et al. 2012). It is shown in the current article that some of this 18th Dynasty glass and the majority of the 19th-20th Dynasty glass had been recycled, not only supporting the general consensus that glass production virtually disappeared by 1250 BC, but that the cobalt source did not necessarily change. It is further proposed, however, that the generally accepted cobalt source for Egyptian glass was not the alum deposits of Egypt's Western Desert, but derived from cobaltiferous siliceous ores, possibly from central Iran. Re-analysis of the compositions of cobalt-blue glass frit found at Amarna, as well as Egyptian and Mesopotamian glass, suggests that the cobalt colourant was a by-product of silver extraction from these ores and can therefore be considered as a concentrated cobalt glass slag, which travelled in the form of a frit to glass producers who added it to locally derived base glasses and/or their precursors. Experiments conducted on ore containing cobalt-nickel arsenides with native silver demonstrate that not only can silver be extracted and that concentrated cobalt glass can be produced simply by adding a flux, but that some components of the ore partition preferentially into the silver or the glass slag, thereby weakening their associations with the other components in archaeological glass. Treating the cobalt-blue colourant as a slag composed of the gangue of a smelting system provides an explanation for the unique elevated levels of alumina and lower levels of potash found in cobalt-blue glasses, as well as providing an explanation for the cessation of cobalt exploitation at the end of the Late Bronze Age. It is suggested that the exhaustion of native silver and siliceous silver ore deposits during the Bronze Age, with argentiferous lead ores becoming the main source of silver, depleted the amount of cobalt available, thereby reducing the amount of glass produced which, in turn, led to increases in recycling during the New Kingdom period.</jats:p

Glutamatergic Synaptic Dysfunction and Obsessive-Compulsive Disorder

Obsessive-compulsive disorder (OCD) is a debilitating neuropsychiatric condition estimated to afflict 1-3% of the world population. The estimated financial impact in the treatment and management of OCD is in the billions of dollars annually in the US alone. At present there is a marked lack of evidence on the specific causes of OCD. Current hypotheses largely focus on the serotonin (5-HT) system on the basis of the effectiveness of selective serotonin reuptake inhibitors (SSRIs) in alleviating symptoms of patients with OCD, yet a considerable fraction of patients are non-responsive or minimally responsive to these agents. Despite this fact, SSRIs have remained the primary pharmacological treatment avenue for OCD. In recent years, multiple lines of evidence have implicated glutamatergic synaptic dysfunction within the cortico-striatal-thalamo-cortical (CSTC) brain circuit in the etiology of OCD and related disorders, thereby prompting intensified effort in the development and evaluation of agents that modulate glutamatergic neurotransmission for the treatment of OCD. With this in mind, here we review the following topics with respect to synaptic dysfunction and the neural circuitry underlying OCD: (1) evidence supporting the critical involvement of the CSTC circuit, (2) genetic studies supporting the involvement of glutamatergic dysfunction, (3) insights from genetic animal models of OCD, and (4) preliminary findings with glutamatergic neurotransmission-modulating agents in the treatment of OCD. Given the putative mechanistic overlap between OCD and the broader OC-spectrum of disorders, unraveling the synaptic basis of OCD has potential to translate into more effective treatments for an array of poorly understood human disorders

Facing Facts: Facial Injuries from Stand-up Electric Scooters

Background Stand-up electric scooters (SES) are a popular public transportation method. Numerous safety concerns have arisen since their recent introduction. Methods A retrospective chart review was performed to identify patients presenting to the emergency departments in Indianapolis, who sustained SES-related injuries. Results A total of 89 patients were included in our study. The average patient age was 29 ± 12.9 years in a predominantly male cohort (65.2%). No patient was documented as wearing a helmet during the event of injury. Alcohol intoxication was noted in 14.6% of accidents. Falling constituted the leading trauma mechanism (46.1%). Injuries were most common on Saturday (24.7%) from 14h00 to 21h59 (55.1%). Injury types included: abrasions/contusions (33.7%), fractures (31.5%), lacerations (27.0%), or joint injuries (18.0%). The head and neck region (H&N) was the most frequently affected site (42.7%). Operative management under general anesthesia was necessary for 13.5% of injuries. Nonoperative management primarily included conservative orthopedic care (34.8%), pain management with nonsteroidal anti-inflammatory drugs (NSAIDs) (34.8%) and/or opioids (4.5%), bedside laceration repairs (27.0%), and wound dressing (10.1%). Individuals sustaining head and neck injuries were more likely to be older (33.8 vs. 25.7 years, p=0.003), intoxicated by alcohol (29.0% vs. 3.9%, p=0.002), and requiring CT imaging (60.5% vs. 9.8%, p <0.001). Conclusion Although SESs provide a convenient transportation modality, unregulated use raises significant safety concerns. More data need to be collected to guide future safety regulations

Transgenic labeling of parvalbumin-expressing neurons with tdTomato

Parvalbumin (PVALB)-expressing fast-spiking interneurons subserve important roles in many brain regions by modulating circuit function and dysfunction of these neurons is strongly implicated in neuropsychiatric disorders including schizophrenia and autism. To facilitate the study of PVALB neuron function we need to be able to identify PVALB neurons in vivo. We have generated a bacterial artificial chromosome (BAC) transgenic mouse line expressing the red fluorophore tdTomato under the control of endogenous regulatory elements of the Pvalb gene locus (JAX # 027395). We show that the tdTomato transgene is faithfully expressed relative to endogenous PVALB expression throughout the brain. Furthermore, targeted patch clamp recordings confirm that the labeled populations in neocortex, striatum, and hippocampus are fast-spiking interneurons based on intrinsic properties. This new transgenic mouse line provides a useful tool to study PVALB neuron function in the normal brain as well as in mouse models of psychiatric disease.National Institute of Mental Health (U.S.) (Grant 5R01MH097104

The GO4KIDDS Brief Adaptive Scale

Background. Accurate measurement of adaptive behaviour is important in both clinical and research contexts. While several good clinical measures exist, as well as brief research measures for adults with ID, there is need for a brief and efficient measure for research with children and youth. We present preliminary psychometric properties of a new scale we developed for such purposes, the GO4KIDDS Brief Adaptive Behaviour Scale. Materials and Methods. A large sample (n=432) of parents of youth (aged 3 to 20) with ID and/or ASD completed an online survey that included the new scale. A subsample of these parents (n=204) also completed the Scales of Independent Behavior-Revised Short Form (Bruininks et al., 1996). Results. The new scale has good internal consistency and correlates strongly with the Scales of Independent Behavior, thus supporting its reliability and validity. Conclusions. Although we do not recommend its use for clinical purposes, the GO4KIDDS Brief Adaptive Behaviour Scale may be useful for survey research with parents of children and youth with developmental disabilities