6,557 research outputs found
Design Modifications for a Small, Affordable Low Intensity Focused Ultrasound Device
Depression is a prevalent and serious medical illness, and while there are antidepressant drugs to mitigate depressive symptoms, 10 - 30% of patients either do not respond or develop a tolerance to these medications. Literature supports that there is an interrelation between the inflammatory response and treatment-resistant depression. A promising method to tackle depressive symptoms is to block the inflammatory signaling pathway with vagus nerve stimulation (VNS), reducing pro-inflammatory cytokine levels. Although electrical VNS devices exist, they are invasive, expensive, and have side effects including voice alteration, dyspnea, and cough. Low intensity focused ultrasound (LIFU) is a promising method that can stimulate a desired region noninvasively and without long term negative side effects. Nonetheless, the existing LIFU devices can be expensive, cumbersome, and large. The Center of Implantable Devices designed a prototype called the SonicNode that incorporates a transducer, matching network, and an amplifier into a 50 mm x 57 mm x 76 mm package. We modified the transducer head and created an intensity map of the focal region to demonstrate the improved performance of the device. The SonicNode and LIFU technology can be employed for long term, noninvasive treatment of a variety of neurological disorders
Treatment and Prevention of Opioid Use Disorder: Challenges and Opportunities
Treatment for opioid use disorder in the United States evolved in response to changing federal policy and advances in science. Inpatient care began in 1935 with the US Public Health Service Hospitals in Lexington, Kentucky, and Fort Worth, Texas. Outpatient clinics emerged in the 1960s to provide aftercare. Research advances led to opioid agonist and opioid antagonist therapies. When patients complete opioid withdrawal, return to use is often rapid and frequently deadly. US and international authorities recommend opioid agonist therapy (i.e., methadone or buprenorphine). Opioid antagonist therapy (i.e., extended-release naltrexone) may also inhibit return to use. Prevention efforts emphasize public and prescriber education, use of prescription drug monitoring programs, and safe medication disposal options. Overdose education and naloxone distribution promote access to rescue medication and reduce opioid overdose fatalities. Opioid use disorder prevention and treatment must embrace evidence-based care and integrate with physical and mental health care
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Variation in Soil Carbon Dioxide Efflux at Two Spatial Scales in a Topographically Complex Boreal Forest
Carbon dynamics of high latitude regions are an important and highly uncertain component of global carbon budgets, and efforts to constrain estimates of soil-atmosphere carbon exchange in these regions are contingent on accurate representations of spatial and temporal variability in carbon fluxes. This study explores spatial and temporal variability in soil-atmosphere carbon dynamics at both fine and coarse spatial scales in a high-elevation, permafrost-dominated boreal black spruce forest. We evaluate the importance of landscape level investigations of soil-atmosphere carbon dynamics by characterizing seasonal trends in soil-atmosphere carbon exchange, describing soil temperature-moisture-respiration relations, and quantifying temporal and spatial variability at two spatial scales: the plot scale (0-5m) and the landscape scale (500-1000m). Plot-scale spatial variability (average variation on a given measurement day) in soil CO2 efflux ranged from a coefficient of variation (CV) 0.25 to 0.69, and plot-scale temporal variability (average variation of plots across measurement days) in efflux ranged from a CV of 0.19 to 0.36. Landscape-scale spatial and temporal variability in efflux was represented by a CV of 0.40 and 0.31 respectively, indicating that plot-scale spatial variability in soil respiration is as great as landscape-scale spatial variability at this site. While soil respiration was related to soil temperature at both the plot and landscape-scale, landscape level descriptions of soil moisture were necessary to define soil respiration-moisture relations. Soil moisture variability was also integral to explaining temporal variability in soil respiration. Our results have important implications for research efforts in high latitude regions where remote study sites make landscape-scale field campaigns challenging
The OLYMPUS Internal Hydrogen Target
An internal hydrogen target system was developed for the OLYMPUS experiment
at DESY, in Hamburg, Germany. The target consisted of a long, thin-walled,
tubular cell within an aluminum scattering chamber. Hydrogen entered at the
center of the cell and exited through the ends, where it was removed from the
beamline by a multistage pumping system. A cryogenic coldhead cooled the target
cell to counteract heating from the beam and increase the density of hydrogen
in the target. A fixed collimator protected the cell from synchrotron radiation
and the beam halo. A series of wakefield suppressors reduced heating from beam
wakefields. The target system was installed within the DORIS storage ring and
was successfully operated during the course of the OLYMPUS experiment in 2012.
Information on the design, fabrication, and performance of the target system is
reported.Comment: 9 pages, 13 figure
Salt marsh pond biogeochemistry changes hourly-to-yearly but does not scale with dimensions or geospatial position
Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Biogeosciences 125(10), (2020): e2020JG005664, doi:10.1029/2020JG005664.Shallow ponds are expanding in many salt marshes with potential impacts on ecosystem functioning. Determining how pond characteristics change over time and scale with physical dimensions and other spatial predictors could facilitate incorporation of ponds into projections of ecosystem change. We evaluated scaling relationships across six differently sized ponds in three regions of the high marshes within the Plum Island EcosystemsâLong Term Ecological Research site (MA, USA). We further characterized diel fluctuations in surface water chemistry in two ponds to understand shortâterm processes that affect emergent properties (e.g., habitat suitability). Primary producers drove oxygen levels to supersaturation during the day, while nighttime respiration resulted in hypoxic to anoxic conditions. Diel swings in oxygen were mirrored by pH and resulted in successive shifts in redoxâsensitive metabolisms, as indicated by nitrate consumption at dusk followed by peaks in ammonium and then sulfide overnight. Abundances of macroalgae and Ruppia maritima correlated with wholeâpond oxygen metabolism rates, but not with surface area (SA), volume (V), or SA:V. Moreover, there were no clear patterns in primary producer abundances, surface water chemistry, or pond metabolism rates across marsh regions supplied by different tidal creeks or that differed in distance to upland borders or creekbanks. Comparisons with data from 2 years prior demonstrate that plant communities and biogeochemical processes are not in steady state. Factors contributing to variability between ponds and years are unclear but likely include infrequent tidal exchange. Temporal and spatial variability and the absence of scaling relationships complicate the integration of high marsh ponds into ecosystem biogeochemical models.Thanks to S. McNichol, S. Jayne, E. Neel, and PIEâLTER (NSFâOCE1238212) for field assistance; I. Forbrich for meteorological data (Giblin & Forbrich, 2018); J. Jennings for dissolved nutrient analyses; J. Seewald for ion chromatograph access; and G. Mariotti for elevation data. C. Wilson and an anonymous reviewer provided comments that greatly improved our manuscript. A. C. S. was supported by NSF (OCE1233678), NOAA (NA14NOS4190145), and Sea Grant (NA14OAR4170104) awards, and A. D. by the MIT Undergraduate Research Opportunities Program.2021-03-1
Clusters in the Luminous Giant HII Regions in M101
(Abridged) We have obtained HST WFPC2 observations of three very luminous but
morphologically different giant HII regions (GHRs) in M101, NGC5461, NGC5462,
and NGC5471, in order to study cluster formation in GHRs. The measured (M_F547M
- M_F675W) colors and M_F547M magnitudes are used to determine the ages and
masses of the cluster candidates with M_F547M <= -9.0. NGC5461 is dominated by
a very luminous core, and has been suggested to host a super-star cluster
(SSC). Our observations show that it contains three R136-class clusters
superposed on a bright stellar background in a small region. This tight group
of clusters may dynamically evolve into an SSC in the future, and may appear
unresolved and be identified as an SSC at large distances, but at present
NGC5461 has no SSCs. NGC5462 has loosely distributed HII regions and clusters
without a prominent core. It has the largest number of cluster candidates among
the three GHRs, but most of them are faint and older than 10 Myr. NGC5471 has
multiple bright HII regions, and contains a large number of faint clusters
younger than 5 Myr. Two of the clusters in NGC5471 are older than R136, but
just as luminous; they may be the most massive clusters in the three GHRs. The
fraction of stars formed in massive clusters is estimated from the clusters'
contribution to the total stellar continuum emission and a comparison of the
ionizing power of the clusters to the ionizing requirement of the associated
HII regions. Both estimates show that <~ 50% of massive stars are formed in
massive clusters. The cluster luminosity functions (CLFs) of the three GHRs
show different slopes. NGC5462 has the steepest CLF and the most loosely
distributed interstellar gas, qualitatively consistent with the hypothesis that
massive clusters are formed in high-pressure interstellar environments.Comment: 36 pages (figures not included), 16 figures (3 of them are color
figures). Figures are in JPEG or GIF format with a lower resolution due to
the size limit of the file. For a higher resolution version of the paper,
please download from http://www.astro.uiuc.edu/~c-chen/clusters.pdf. accepted
for ApJ (scheduled for the ApJ 2005 February issue
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