204 research outputs found

    Decoding Working-Memory Load During n-Back Task Performance from High Channel NIRS Data

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    Near-infrared spectroscopy (NIRS) can measure neural activity through blood oxygenation changes in the brain in a wearable form factor, enabling unique applications for research in and outside the lab. NIRS has proven capable of measuring cognitive states such as mental workload, often using machine learning (ML) based brain-computer interfaces (BCIs). To date, NIRS research has largely relied on probes with under ten to several hundred channels, although recently a new class of wearable NIRS devices with thousands of channels has emerged. This poses unique challenges for ML classification, as NIRS is typically limited by few training trials which results in severely under-determined estimation problems. So far, it is not well understood how such high-resolution data is best leveraged in practical BCIs and whether state-of-the-art (SotA) or better performance can be achieved. To address these questions, we propose an ML strategy to classify working-memory load that relies on spatio-temporal regularization and transfer learning from other subjects in a combination that has not been used in previous NIRS BCIs. The approach can be interpreted as an end-to-end generalized linear model and allows for a high degree of interpretability using channel-level or cortical imaging approaches. We show that using the proposed methodology, it is possible to achieve SotA decoding performance with high-resolution NIRS data. We also replicated several SotA approaches on our dataset of 43 participants wearing a 3198 dual-channel NIRS device while performing the n-Back task and show that these existing methods struggle in the high-channel regime and are largely outperformed by the proposed method. Our approach helps establish high-channel NIRS devices as a viable platform for SotA BCI and opens new applications using this class of headset while also enabling high-resolution model imaging and interpretation.Comment: 29 pages, 9 figures. Under revie

    Novel periodic alternating tangential filtration harvest approach provides incresed volumetric productivity

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    Perfusion cell culture processes provide opportunities to increase product yield through improved cell growth, increased productivity and extended process duration. Most commonly, perfusion cell culture also leads to a continuous harvest operation and collection of harvested cell culture fluid to be processed downstream. As an alternative to continuous harvest, we evaluated instead a periodic harvest approach applied to a non-steady state perfusion cell culture process using alternative tangential flow (ATF). In this ATF perfusion process, product is first accumulated in the bioreactor using ultrafiltration for 15 days with the product then being harvested by microfiltration at end of the process. To further extend the culture time beyond 15 days and maximize productivity, we investigated a sequence of five periodic harvests from a single upstream bioreactor run. The periodic harvests were achieved using an ATF configuration in which ultrafiltration and microfiltration hollow fiber filters were stacked in series (Figure 1). The ultrafiltration hollow fiber retains the product while the microfiltration filter allows product to be collected in the permeate. Permeate was only drawn from the microfiltration filter during the periodic harvest cycles while the permeate was drawn from the ultrafiltration filter during the none harvest cycle periods. This allowed for the accumulation of product in the bioreactor between the periodic harvests. Five harvest cycles were conducted over a 24-day perfusion process. Each harvest cycle was collected for a day with the first harvest cycle starting on day 11. Please click Additional Files below to see the full abstract

    Assumptionitis in Strategy

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    17 USC 105 interim-entered record; under review.The article of record as published may be found at https://thestrategybridge.org/the-bridge/2021/6/21/assumptionitis-in-strategyU.S. Government affiliation is unstated in article text

    Factors Influencing Publication Rates among Counselor Educators

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    Factors influencing publication rates were examined among a simple random sample of 257 counselor educators. The factors of: a) gender, b) experience as a counselor educator, c) faculty rank, and d) working in a research institution predicted peer-reviewed publication rates in the counselor educator sample, with a large effect size. Additional results, limitations of the investigation, areas for future research, and implications for counselor educators are discussed

    Method Development for Structural Assessment of Nanolipoprotein Particles with and without Cross-linked Lipids

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    Membrane proteins make up approximately 30% of the cellular proteome and account for over 60% of pharmaceutical targets.1 Determining the structures of this class of proteins is critical to our understanding of disease states and will advance rational drug design. But membrane proteins have limited solubility, rarely form large crystals that diffract well, and often misfold outside of a bilayer, hindering crystallographic studies.1 Nanolipoprotein particles (NLPs) have arisen as a platform to readily solubilize membrane proteins while mimicking a native lipid environment. NLPs consist of a discoidal phospholipid bilayer encircled by an apolipoprotein belt. In an effort to optimize and improve crystallization of empty NLPs, we altered the fluidity of the lipid bilayer by incorporating photoactive DiynePC phospholipids in the lipid bilayer, forming cross-linked nanoparticles (X-NLPs). Here, we used a cell-free expression system with apolipoprotein A1 (ApoA1) plasmid and micellar lipids to assemble NLPs. Based on high throughput crystallization screening data, we reproduced and validated crystallization conditions for X-NLPs and optimized conditions for non-crosslinked NLPs (DMPC NLPs)

    A cricket Gene Index: a genomic resource for studying neurobiology, speciation, and molecular evolution

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    <p>Abstract</p> <p>Background</p> <p>As the developmental costs of genomic tools decline, genomic approaches to non-model systems are becoming more feasible. Many of these systems may lack advanced genetic tools but are extremely valuable models in other biological fields. Here we report the development of expressed sequence tags (EST's) in an orthopteroid insect, a model for the study of neurobiology, speciation, and evolution.</p> <p>Results</p> <p>We report the sequencing of 14,502 EST's from clones derived from a nerve cord cDNA library, and the subsequent construction of a Gene Index from these sequences, from the Hawaiian trigonidiine cricket <it>Laupala kohalensis</it>. The Gene Index contains 8607 unique sequences comprised of 2575 tentative consensus (TC) sequences and 6032 singletons. For each of the unique sequences, an attempt was made to assign a provisional annotation and to categorize its function using a Gene Ontology-based classification through a sequence-based comparison to known proteins. In addition, a set of unique 70 base pair oligomers that can be used for DNA microarrays was developed. All Gene Index information is posted at the DFCI Gene Indices web page</p> <p>Conclusion</p> <p>Orthopterans are models used to understand the neurophysiological basis of complex motor patterns such as flight and stridulation. The sequences presented in the cricket Gene Index will provide neurophysiologists with many genetic tools that have been largely absent in this field. The cricket Gene Index is one of only two gene indices to be developed in an evolutionary model system. Species within the genus <it>Laupala </it>have speciated recently, rapidly, and extensively. Therefore, the genes identified in the cricket Gene Index can be used to study the genomics of speciation. Furthermore, this gene index represents a significant EST resources for basal insects. As such, this resource is a valuable comparative tool for the understanding of invertebrate molecular evolution. The sequences presented here will provide much needed genomic resources for three distinct but overlapping fields of inquiry: neurobiology, speciation, and molecular evolution.</p

    Homeotic transformation induced by protein transduction

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    One of the most fundamental features of living organisms is that cells are separated from their external environment by a thin, but highly complex plasma membrane constituted of a lipid bilayer. Although, the lipid bilayer is only a few nanometers in width, it is impermeable to most molecules apart from small hydrophobic ones. The ability of small molecules to diffuse through a lipid bilayer is related to their lipid solubility. Hydrophilic macromolecular Antennapedia homeodomain peptide has been shown to be able to translocate from extracellular space into the cytoplasm of cells in a receptor-independent manner. Its third α-helix domain, designated as “Penetratin”, was proposed to be the functional transduction domain that is responsible for the translocation, and it is widely used for intracellular delivery of various exogenous proteins. Although Penetratin has been regarded to be the only element conferring the capacity of its parent polypeptide to penetrate through the plasma membrane, we found that the complete Antennapedia homeodomain exhibits an appreciably higher level of translocation efficiency as compared to Penetratin. Pharmacological analysis demonstrated that macropinocytic endocytosis plays a significant role underlying the process of the homeodomain internalization, and this is consistent with the observation that internalized polypeptide co-localizes with a fluid phase dye. Our studies identify macropinocytosis as a major mechanism by which Antennapedia homeodomain obtains the access to the interior of cells. In the process of macropinocytosis, signaling from the plasma membrane is required for actin remodeling to generate mechanical deformation forces; the interaction between positively charged Antennapedia homeodomain and negatively charged extracellular heparan sulfate could trigger the signaling cascade for fluid phase endocytosis. This would presumably explain why positively charged peptides, polymers, and liposomes are able to penetrate cells. As a fluid phase macropinocytosis provides cells with a way to non-selectively internalize large quantities of solute, it represents an effective means for drug delivery into cells. Both of “Penetratin” and Antennapedia homeodomain exploit macropinocytosis to a certain extent, the comparison between them may advance our understanding of the mechanisms triggering macropinocytotic endocytosis

    Sex Disparities in Access to Acute Stroke Care: Can Telemedicine Mitigate this Effect?

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    Background: Women have more frequent and severe ischemic strokes than men, and are less likely to receive treatment for acute stroke. Primary stroke centers (PSCs) have been shown to utilize treatment more frequently. Further, as telemedicine (TM) has expanded access to acute stroke care we sought to investigate the association between PSC, TM and access to acute stroke care in the state of Texas. Methods: Texas hospitals and resources were identified from the 2009 American Hospital Association Annual Survey. Hospitals were categorized as: (1) stand-alone PSCs not using telemedicine for acute stroke care, (2) PSCs using telemedicine for acute stroke care (PSC-TM), (3) non-PSC hospitals using telemedicine for acute stroke care, or (4) non-PSC hospitals not using telemedicine for acute stroke care. The proportion of the population who could reach a PSC within 60 minutes was determined for stand-alone PSCs, PSC-TM, and non-PSCs using TM for stroke care. Results: Overall, women were as likely to have 60-minute access to a PSC or PSC-TM as their male counterparts (POR 1.02, 95% CI 1.02-1.03). Women were also just as likely to have access to acute stroke care via PSC or PSC-TM or TM as men (POR 1.03, 95% CI 1.02-1.04). Discussion: Our study found no sex disparities in access to stand alone PSCs or to hospitals using TM in the state of Texas. The results of this study suggest that telemedicine can be used as part of an inclusive strategy to improve access to care equally for men and women
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