Publications by authors named "Daniel Bear"

Background: The COVID-19 pandemic and the accompanying measures to mitigate infection affected many areas of society, including the supply and use of cannabis. This paper explored how patterns of behaviour among people who cultivate cannabis were affected by the COVID-19 pandemic and restrictions.

Methods: An anonymous web survey of people who cultivated cannabis was conducted from Aug 2020 to Sep 2021, spanning 18 countries and 11 languages (N = 11,479).

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The concept of harm reduction was a radical departure from a century of stigmatizing demand reduction initiatives targeted at people who use drugs. In fact, since the early 1980's Harm Reduction has been used with great success to protect the lives and wellbeing of these individuals. When employed with people who use opioids, the relevancy and importance of harm reduction are easy to grasp because the potential dangers are both quite visible and profound.

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Article Synopsis
  • - The article explores the role of small-scale cannabis growers in distribution, highlighting that many are not part of criminal gangs but instead engage in various types of supply practices across different countries.
  • - Using data from a comprehensive survey of cannabis growers in 18 countries, it finds that most growers distribute surplus cannabis, with sharing and gifting being more common than selling.
  • - The study concludes that, while profit motives exist, many small-scale sellers prioritize social connections over financial gain, indicating a shift toward the normalization of cannabis supply in low-end markets.
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The mammalian olfactory system detects and discriminates between millions of odorants to elicit appropriate behavioral responses. While much has been learned about how olfactory sensory neurons detect odorants and signal their presence, how specific innate, unlearned behaviors are initiated in response to ethologically relevant odors remains poorly understood. Here, we show that the 4-transmembrane protein CD20, also known as MS4A1, is expressed in a previously uncharacterized subpopulation of olfactory sensory neurons in the main olfactory epithelium of the murine nasal cavity and functions as a mammalian olfactory receptor that recognizes compounds produced by mouse predators.

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Background: Little is known about cannabis use problems among individuals who use cannabis for medical purposes and whether rates and determinants of cannabis use problems in medical users differ to those observed among individuals using for recreational reasons. This study examines whether Severity of Dependence Scale (SDS) scores differ across individuals who use self-grown cannabis for the following reasons: "recreational only", "medical and recreational" and "medical only". Furthermore, the study tests whether cannabis use frequency, cannabis strain, and type of cannabis influences the strength of the association between purpose of use and cannabis use problems.

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The mammalian olfactory system detects and discriminates between millions of odorants to elicit appropriate behavioral responses. While much has been learned about how olfactory sensory neurons detect odorants and signal their presence, how specific innate, unlearned behaviors are initiated in response to ethologically relevant odors remains poorly understood. Here, we show that the 4-transmembrane protein CD20, also known as MS4A1, is expressed in a previously uncharacterized subpopulation of olfactory sensory neurons in the main olfactory epithelium of the murine nasal cavity and functions as a mammalian odorant receptor that recognizes compounds produced by mouse predators.

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The mammalian olfactory system detects and discriminates between millions of odorants to elicit appropriate behavioral responses. While much has been learned about how olfactory sensory neurons detect odorants and signal their presence, how specific innate, unlearned behaviors are initiated in response to ethologically relevant odors remains poorly understood. Here, we show that the 4-transmembrane protein CD20, also known as MS4A1, is expressed in a previously uncharacterized subpopulation of olfactory sensory neurons in the main olfactory epithelium of the murine nasal cavity and functions as a mammalian odorant receptor that recognizes compounds produced by mouse predators.

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The computational role of the abundant feedback connections in the ventral visual stream is unclear, enabling humans and nonhuman primates to effortlessly recognize objects across a multitude of viewing conditions. Prior studies have augmented feedforward convolutional neural networks (CNNs) with recurrent connections to study their role in visual processing; however, often these recurrent networks are optimized directly on neural data or the comparative metrics used are undefined for standard feedforward networks that lack these connections. In this work, we develop task-optimized convolutional recurrent (ConvRNN) network models that more correctly mimic the timing and gross neuroanatomy of the ventral pathway.

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The olfactory system's ability to detect and discriminate between the vast array of chemicals present in the environment is critical for an animal's survival. In mammals, the first step of this odor processing is executed by olfactory sensory neurons, which project their axons to a stereotyped location in the olfactory bulb (OB) to form glomeruli. The stereotyped positioning of glomeruli in the OB suggests an importance for this organization in odor perception.

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Background: In 2015, a new Liberal Government came to power in Canada, elected on a platform that included legalization and regulation of cannabis for recreational purposes. Their legislation, based on recommendations from a Federal Task Force on Marijuana Legalization and Regulation, is due in early April 2017.

Methods: This commentary utilizes Canadian Federal policy papers, previous literature, and internal and international agreements to examine two key areas critical to the development of a nationwide regulated market for cannabis in Canada; the need to overcome restrictions to legalizing cannabis in United Nations' drug control treaties, and the unique challenges that non-medical cannabis creates for navigating interprovincial trade policies in Canada.

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Evolution sculpts the olfactory nervous system in response to the unique sensory challenges facing each species. In vertebrates, dramatic and diverse adaptations to the chemical environment are possible because of the hierarchical structure of the olfactory receptor (OR) gene superfamily: expansion or contraction of OR subfamilies accompanies major changes in habitat and lifestyle; independent selection on OR subfamilies can permit local adaptation or conserved chemical communication; and genetic variation in single OR genes can alter odor percepts and behaviors driven by precise chemical cues. However, this genetic flexibility contrasts with the relatively fixed neural architecture of the vertebrate olfactory system, which requires that new olfactory receptors integrate into segregated and functionally distinct neural pathways.

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Odor perception in mammals is mediated by parallel sensory pathways that convey distinct information about the olfactory world. Multiple olfactory subsystems express characteristic seven-transmembrane G-protein-coupled receptors (GPCRs) in a one-receptor-per-neuron pattern that facilitates odor discrimination. Sensory neurons of the "necklace" subsystem are nestled within the recesses of the olfactory epithelium and detect diverse odorants; however, they do not express known GPCR odor receptors.

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We developed a teaching-led research project to empirically ground methodological reflection about digital ethnography. Drawing on Cordelois' collective ethnographic observation approach, fifteen emerging professionals (from a private general education university and a Police Academy in Bogota) collaborated in a method seminar on digital ethnography. They worked in cross-institutional research teams, each carrying SenseCams for 3 days.

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We used genome-wide sequencing methods to study stimulus-dependent enhancer function in mouse cortical neurons. We identified approximately 12,000 neuronal activity-regulated enhancers that are bound by the general transcriptional co-activator CBP in an activity-dependent manner. A function of CBP at enhancers may be to recruit RNA polymerase II (RNAPII), as we also observed activity-regulated RNAPII binding to thousands of enhancers.

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Although many transcription factors are known to control important aspects of neural development, the genome-wide programs that are directly regulated by these factors are not known. We have characterized the genetic program that is activated by MEF2, a key regulator of activity-dependent synapse development. These MEF2 target genes have diverse functions at synapses, revealing a broad role for MEF2 in synapse development.

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A critical step in cell division is formation of the mitotic spindle, which is a bipolar array of microtubules that mediates chromosome separation. Here, we report that the SCL-interrupting locus (SIL), a vertebrate-specific cytosolic protein, is necessary for proper mitotic spindle organization in zebrafish and human cells. A homozygous lethal zebrafish mutant, cassiopeia (csp), was identified by a genetic screen for mitotic mutant.

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