12,948 research outputs found
What can managers learn online? Investigating possibilities for active understanding in the online MBA classroom
Online MBAs have become integral to business schools’ portfolios and the number of MBA students opting for an online version looks set to grow. In the wake of well documented critiques of traditional MBA formats, this expansion prompted us to examine the potential for critically reflexive learning ideals in asynchronous MBA learning environments. Building the Community of Inquiry (CoI) model we elaborate elements of Bakhtin and Shotter’s dialogism to develop the notion of ‘active understanding’ as a means to study an online MBA classroom. We present two illustrative episodes to show how aspects of active understanding may unfold and we point to the role of infrastructure, curriculum and instructor interventions in developing more genuine dialogical exchanges. Our findings suggest that online MBA course designers can learn from CoI approaches to which we add that critically reflexive learning is situationally sensitive; requiring the capacity to create and recognize nuance and difference in the written communication; making the other the focus of learning. We conclude with implications for pedagogy and technology infrastructure
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Endocardial ablation of ventricular ectopic beats arising from the basal inferoseptal process of the left ventricle
Background
Idiopathic ventricular ectopy (VE) shows predilection to sites within the left ventricular (LV) base such as the outflow tract/aortic sinuses, LV summit, and areas adjacent to the aortomitral continuity. We characterize VE arising from the inferior septum of the LV base that was successfully managed by LV endocardial ablation from the inferoseptal recess of the LV.
Objective
The purpose of this study was to determine the incidence, electrocardiographic (ECG) findings, electrophysiological findings, and anatomical features associated with VE arising from the basal inferoseptal process of the LV (ISP-LV) ablated using an LV endocardial approach via the inferoseptal recess of the LV.
Methods
A total of 425 consecutive patients undergoing VE ablation between January 1, 2012 and December 31, 2016 at 3 centers were evaluated. Demographic characteristics, ECG findings, and procedural data were analyzed for patients with ISP-LV VEs.
Results
Seven (1.5%) had a site of origin from the ISP-LV. Common ECG findings were a right bundle branch block concordant pattern or an atypical left bundle branch block early transition pattern, suggestive of a basal origin with a left superior axis, a biphasic QRS complex in lead aVR, and a small s wave in lead V6. Earliest activation was seen in an area below the outflow tract accessed from the inferoseptal recess inferior to the His bundle. In 3 cases, transient junctional rhythm was seen during ablation. All cases were ablated successfully with no complications.
Conclusion
VE arising from the ISP-LV represents a distinct subset of idiopathic arrhythmia and can be successfully treated by endocardial catheter ablation from the inferoseptal recess. They share common surface ECG and electrophysiological findings with special anatomical features that need recognition for successful catheter ablation
A Novel Wayfinding Service for Empowering Physical Activity
A wayfinding service for empowering physical activity is presented. The service finds routes that involve multi-modal transportation where walking is always one mode. The service is based on the new concept of multi-modal transportation with multi-criteria walking. A prototype of the service is developed and a new empowerment approach for it is discussed
Cerebrospinal fluid interferon alpha levels correlate with neurocognitive impairment in ambulatory HIV-Infected individuals
HIV-associated neurocognitive disorders (HANDs) continue to be common and are associated with increased morbidity and mortality. However, the underlying mechanisms in the combination antiretroviral therapy (cART) era are not fully understood. Interferon alpha (IFNα) is an antiviral cytokine found to be elevated in the cerebrospinal fluid (CSF) of individuals with advanced HIV-associated dementia in the pre-cART era. In this cross-sectional study, we investigated the association between IFNα and neurocognitive performance in ambulatory HIV-infected individuals with milder impairment. An eight-test neuropsychological battery representing six cognitive domains was administered. Individual scores were adjusted for demographic characteristics, and a composite neuropsychological score (NPT-8) was calculated. IFNα and CSF neurofilament light chain (NFL) levels were measured using enzyme-linked immunosorbent assay (ELISA). There were 15 chronically infected participants with a history of significant immunocompromise (median nadir CD4+ of 49 cells/μl). Most participants were neurocognitively impaired (mean global deficit score of 0.86). CSF IFNα negatively correlated with three individual tests (Trailmaking A, Trailmaking B, and Stroop Color-Word) as well as the composite NPT-8 score (r = −0.67, p = 0.006). These negative correlations persisted in multivariable analyses adjusting for chronic hepatitis B and C. Additionally, CSF IFNα correlated strongly with CSF NFL, a marker of neuronal damage (rho = 0.748, p = 0.0013). These results extend findings from individuals with severe HIV-associated dementia in the pre-cART era and suggest that IFNα may continue to play a role in HAND pathogenesis during the cART era. Further investigation into the role of IFNα is indicated
An inhibitory pull-push circuit in frontal cortex.
Push-pull is a canonical computation of excitatory cortical circuits. By contrast, we identify a pull-push inhibitory circuit in frontal cortex that originates in vasoactive intestinal polypeptide (VIP)-expressing interneurons. During arousal, VIP cells rapidly and directly inhibit pyramidal neurons; VIP cells also indirectly excite these pyramidal neurons via parallel disinhibition. Thus, arousal exerts a feedback pull-push influence on excitatory neurons-an inversion of the canonical push-pull of feedforward input
The Pioneer Anomaly
Radio-metric Doppler tracking data received from the Pioneer 10 and 11
spacecraft from heliocentric distances of 20-70 AU has consistently indicated
the presence of a small, anomalous, blue-shifted frequency drift uniformly
changing with a rate of ~6 x 10^{-9} Hz/s. Ultimately, the drift was
interpreted as a constant sunward deceleration of each particular spacecraft at
the level of a_P = (8.74 +/- 1.33) x 10^{-10} m/s^2. This apparent violation of
the Newton's gravitational inverse-square law has become known as the Pioneer
anomaly; the nature of this anomaly remains unexplained. In this review, we
summarize the current knowledge of the physical properties of the anomaly and
the conditions that led to its detection and characterization. We review
various mechanisms proposed to explain the anomaly and discuss the current
state of efforts to determine its nature. A comprehensive new investigation of
the anomalous behavior of the two Pioneers has begun recently. The new efforts
rely on the much-extended set of radio-metric Doppler data for both spacecraft
in conjunction with the newly available complete record of their telemetry
files and a large archive of original project documentation. As the new study
is yet to report its findings, this review provides the necessary background
for the new results to appear in the near future. In particular, we provide a
significant amount of information on the design, operations and behavior of the
two Pioneers during their entire missions, including descriptions of various
data formats and techniques used for their navigation and radio-science data
analysis. As most of this information was recovered relatively recently, it was
not used in the previous studies of the Pioneer anomaly, but it is critical for
the new investigation.Comment: 165 pages, 40 figures, 16 tables; accepted for publication in Living
Reviews in Relativit
Translational outcomes in a full gene deletion of ubiquitin protein ligase E3A rat model of Angelman syndrome.
Angelman syndrome (AS) is a rare neurodevelopmental disorder characterized by developmental delay, impaired communication, motor deficits and ataxia, intellectual disabilities, microcephaly, and seizures. The genetic cause of AS is the loss of expression of UBE3A (ubiquitin protein ligase E6-AP) in the brain, typically due to a deletion of the maternal 15q11-q13 region. Previous studies have been performed using a mouse model with a deletion of a single exon of Ube3a. Since three splice variants of Ube3a exist, this has led to a lack of consistent reports and the theory that perhaps not all mouse studies were assessing the effects of an absence of all functional UBE3A. Herein, we report the generation and functional characterization of a novel model of Angelman syndrome by deleting the entire Ube3a gene in the rat. We validated that this resulted in the first comprehensive gene deletion rodent model. Ultrasonic vocalizations from newborn Ube3am-/p+ were reduced in the maternal inherited deletion group with no observable change in the Ube3am+/p- paternal transmission cohort. We also discovered Ube3am-/p+ exhibited delayed reflex development, motor deficits in rearing and fine motor skills, aberrant social communication, and impaired touchscreen learning and memory in young adults. These behavioral deficits were large in effect size and easily apparent in the larger rodent species. Low social communication was detected using a playback task that is unique to rats. Structural imaging illustrated decreased brain volume in Ube3am-/p+ and a variety of intriguing neuroanatomical phenotypes while Ube3am+/p- did not exhibit altered neuroanatomy. Our report identifies, for the first time, unique AS relevant functional phenotypes and anatomical markers as preclinical outcomes to test various strategies for gene and molecular therapies in AS
Statistical Signatures of Photon Localization
The realization that electron localization in disordered systems (Anderson
localization) is ultimately a wave phenomenon has led to the suggestion that
photons could be similarly localized by disorder. This conjecture attracted
wide interest because the differences between photons and electrons - in their
interactions, spin statistics, and methods of injection and detection - may
open a new realm of optical and microwave phenomena, and allow a detailed study
of the Anderson localization transition undisturbed by the Coulomb interaction.
To date, claims of three-dimensional photon localization have been based on
observations of the exponential decay of the electromagnetic wave as it
propagates through the disordered medium. But these reports have come under
close scrutiny because of the possibility that the decay observed may be due to
residual absorption, and because absorption itself may suppress localization.
Here we show that the extent of photon localization can be determined by a
different approach - measurement of the relative size of fluctuations of
certain transmission quantities. The variance of relative fluctuations
accurately reflects the extent of localization, even in the presence of
absorption. Using this approach, we demonstrate photon localization in both
weakly and strongly scattering quasi-one-dimensional dielectric samples and in
periodic metallic wire meshes containing metallic scatterers, while ruling it
out in three-dimensional mixtures of aluminum spheres.Comment: 5 pages, including 4 figure
A standard, single dose of inhaled terbutaline attenuates hyperpnoea-induced bronchoconstriction and mast cell activation in athletes
Release of broncho-active mediators from mast cells during exercise hyperpnoea is a key factor in the pathophysiology of exercise-induced bronchoconstriction (EIB). Our aim was to investigate the effect of a standard, single dose of an inhaled β2-adrenoceptor agonist on mast cell activation in response to dry air hyperpnoea in athletes with EIB. Twenty-seven athletes with EIB completed a randomised, double blind, placebo-controlled, crossover study. Terbutaline (0.5 mg) or placebo was inhaled15 min prior to 8 min of eucapnic voluntary hyperpnoea (EVH) with dry air. Pre- and post-bronchial challenge, urine samples were analysed by enzyme immunoassay for 11β-prostaglandin(PG)F2α. The maximum fall in forced expiratory volume in 1 sec(FEV1) of 14 (12-20)% (median and interquartile range) following placebo was attenuated to 7 (5-9)% with the administration of terbutaline (P<0.001). EVH caused a significant increase in 11β-PGF2α from (27-57) ng·mmol creatinine-1 at baseline to (43-72) ng·mmol creatinine-1 at its peak post-EVH following placebo (P=0.002). The rise in 11β-PGF2α was inhibited with administration of terbutaline: 39 (28-44) ng·mmol creatinine-1 at baseline vs. 40 (33-58) ng·mmol creatinine-1 at its peak post-EVH (P=0.118). These data provide novel in vivo evidence of mast cell stabilisation following inhalation of a standard dose of terbutaline prior to bronchial provocation with EVH in athletes with EIB
Two rapid assays for screening of patulin biodegradation
Artículo sobre distintos ensayos para comprobar la biodegradación de la patulinaThe mycotoxin patulin is produced by the blue
mould pathogen Penicillium expansum in rotting apples
during postharvest storage. Patulin is toxic to a wide range
of organisms, including humans, animals, fungi and bacteria.
Wash water from apple packing and processing
houses often harbours patulin and fungal spores, which can
contaminate the environment. Ubiquitous epiphytic yeasts,
such as Rhodosporidium kratochvilovae strain LS11 which
is a biocontrol agent of P. expansum in apples, have the
capacity to resist the toxicity of patulin and to biodegrade
it. Two non-toxic products are formed. One is desoxypatulinic
acid. The aim of the work was to develop rapid,
high-throughput bioassays for monitoring patulin degradation
in multiple samples. Escherichia coli was highly
sensitive to patulin, but insensitive to desoxypatulinic acid.
This was utilized to develop a detection test for patulin,
replacing time-consuming thin layer chromatography or
high-performance liquid chromatography. Two assays for patulin degradation were developed, one in liquid medium
and the other in semi-solid medium. Both assays allow the
contemporary screening of a large number of samples. The
liquid medium assay utilizes 96-well microtiter plates and
was optimized for using a minimum of patulin. The semisolid
medium assay has the added advantage of slowing
down the biodegradation, which allows the study and isolation
of transient degradation products. The two assays are
complementary and have several areas of utilization, from
screening a bank of microorganisms for biodegradation
ability to the study of biodegradation pathways
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