1,440 research outputs found
Simultaneous measurement of quality factor and wavelength shift by phase shift microcavity ring down spectroscopy
Optical resonant microcavities with ultra high quality factors are widely
used for biosensing. Until now, the primary method of detection has been based
upon tracking the resonant wavelength shift as a function of biodetection
events. One of the sources of noise in all resonant-wavelength shift
measurements is the noise due to intensity fluctuations of the laser source. An
alternative approach is to track the change in the quality factor of the
optical cavity by using phase shift cavity ring down spectroscopy, a technique
which is insensitive to the intensity fluctuations of the laser source. Here,
using biotinylated microtoroid resonant cavities, we show simultaneous
measurement of the quality factor and the wavelength shift by using phase shift
cavity ring down spectroscopy. These measurements were performed for
disassociation phase of biotin-streptavidin reaction. We found that the
disassociation curves are in good agreement with the previously published
results. Hence, we demonstrate not only the application of phase shift cavity
ring down spectroscopy to microcavities in the liquid phase but also
simultaneous measurement of the quality factor and the wavelength shift for the
microcavity biosensors in the application of kinetics measurements
Bridging the Semantic Gap in Multimedia Information Retrieval: Top-down and Bottom-up approaches
Semantic representation of multimedia information is vital for enabling the kind of multimedia search capabilities that professional searchers require. Manual annotation is often not possible because of the shear scale of the multimedia information that needs indexing. This paper explores the ways in which we are using both top-down, ontologically driven approaches and bottom-up, automatic-annotation approaches to provide retrieval facilities to users. We also discuss many of the current techniques that we are investigating to combine these top-down and bottom-up approaches
Anxiety Shapes Amygdala-Prefrontal Dynamics During Movie Watching
Background:
A well-characterized amygdala–dorsomedial prefrontal circuit is thought to be crucial for threat vigilance during anxiety. However, engagement of this circuitry within relatively naturalistic paradigms remains unresolved. //
Methods:
Using an open functional magnetic resonance imaging dataset (Cambridge Centre for Ageing Neuroscience; n = 630), we sought to investigate whether anxiety correlates with dynamic connectivity between the amygdala and dorsomedial prefrontal cortex during movie watching. //
Results:
Using an intersubject representational similarity approach, we saw no effect of anxiety when comparing pairwise similarities of dynamic connectivity across the entire movie. However, preregistered analyses demonstrated a relationship between anxiety, amygdala-prefrontal dynamics, and anxiogenic features of the movie (canonical suspense ratings). Our results indicated that amygdala-prefrontal circuitry was modulated by suspense in low-anxiety individuals but was less sensitive to suspense in high-anxiety individuals. We suggest that this could also be related to slowed habituation or amplified anticipation. Moreover, a measure of threat-relevant attentional bias (accuracy/reaction time to fearful faces) demonstrated an association with connectivity and suspense. //
Conclusions:
Overall, this study demonstrated the presence of anxiety-relevant differences in connectivity during movie watching, varying with anxiogenic features of the movie. Mechanistically, exactly how and when these differences arise remains an opportunity for future research
Threat vigilance and intrinsic amygdala connectivity
A well-documented amygdala-dorsomedial prefrontal circuit is theorized to promote attention to threat (“threat vigilance”). Prior research has implicated a relationship between individual differences in trait anxiety/vigilance, engagement of this circuitry, and anxiogenic features of the environment (e.g., through threat-of-shock and movie-watching). In the present study, we predicted that—for those scoring high in self-reported anxiety and a behavioral measure of threat vigilance—this circuitry is chronically engaged, even in the absence of anxiogenic stimuli. Our analyses of resting-state fMRI data (N = 639) did not, however, provide evidence for such a relationship. Nevertheless, in our planned exploratory analyses, we saw a relationship between threat vigilance behavior (but not self-reported anxiety) and intrinsic amygdala-periaqueductal gray connectivity. Here, we suggest this subcortical circuitry may be chronically engaged in hypervigilant individuals, but that amygdala-prefrontal circuitry may only be engaged in response to anxiogenic stimuli
Pathways to Economic Outcomes and the Impact of Health: Comparing Hispanic and Non-Hispanic Adults after Foster Care
Abstract
This study examines the financial outcomes in adulthood of Hispanics (N = 87) and White (Non-Hispanic, N = 498) persons placed in foster care during childhood. It uses the Casey Family Programs National Alumni Study (CFPNAS) database. Path models including predictors such as gender, education, having a partner, preparation for leaving care, and problem characteristics yielded predominantly similar effects for Hispanic and White Non-Hispanic respondents. The direct effect of physical and mental health conditions such as physical or learning disability, visual or hearing impairments, or DSM disorders more strongly predicted negative outcomes for White (Non-Hispanic) respondents than for Hispanic ones
Habitat‐related error in estimating temperatures from leaf margins in a humid tropical forest
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142103/1/ajb21096.pd
A multifactorial role for P. falciparum malaria in endemic Burkitt\u27s lymphoma pathogenesis
Endemic Burkitt\u27s lymphoma (eBL) arises from the germinal center (GC). It is a common tumor of young children in tropical Africa and its occurrence is closely linked geographically with the incidence of P. falciparum malaria. This association was noted more than 50 years ago. Since then we have learned that eBL contains the oncogenic herpes virus Epstein-Barr virus (EBV) and a defining translocation that activates the c-myc oncogene. However the link to malaria has never been explained. Here we provide evidence for a mechanism arising in the GC to explain this association. Accumulated evidence suggests that eBL arises in the GC when deregulated expression of AID (Activation-induced cytidine deaminase) causes a c-myc translocation in a cell latently infected with Epstein-Barr virus (EBV). Here we show that P. falciparum targets GC B cells via multiple pathways to increase the risk of eBL. 1. It causes deregulated expression of AID, thereby increasing the risk of a c-myc translocation. 2. It increases the number of B cells transiting the GC. 3. It dramatically increases the frequency of these cells that are infected with EBV and therefore protected from c-myc induced apoptosis. We propose that these activities combine synergistically to dramatically increase the incidence of eBL in individuals infected with malaria
A variational problem on Stiefel manifolds
In their paper on discrete analogues of some classical systems such as the
rigid body and the geodesic flow on an ellipsoid, Moser and Veselov introduced
their analysis in the general context of flows on Stiefel manifolds. We
consider here a general class of continuous time, quadratic cost, optimal
control problems on Stiefel manifolds, which in the extreme dimensions again
yield these classical physical geodesic flows. We have already shown that this
optimal control setting gives a new symmetric representation of the rigid body
flow and in this paper we extend this representation to the geodesic flow on
the ellipsoid and the more general Stiefel manifold case. The metric we choose
on the Stiefel manifolds is the same as that used in the symmetric
representation of the rigid body flow and that used by Moser and Veselov. In
the extreme cases of the ellipsoid and the rigid body, the geodesic flows are
known to be integrable. We obtain the extremal flows using both variational and
optimal control approaches and elucidate the structure of the flows on general
Stiefel manifolds.Comment: 30 page
Leuprolide Acetate 1-Month Depot for Central Precocious Puberty: Hormonal Suppression and Recovery
Methods. This prospective US multicenter trial of leuprolide acetate 1-month depot (7.5–15 mg) for central precocious puberty utilized an open-label treatment period, long-term follow-up, and adult callback. Forty-nine females <9 years old with Tanner breast stage ≥2 before 8 years and 6 males <10 years old with Tanner genital stage ≥2 before 9 years with stimulated LH ≥10 IU/L and bone age advance ≥1 year were enrolled. Results. Subjects were treated for 3.9 ± 2.0 years. Mean peak GnRH-stimulated LH and FSH were prepubertal after the first dose and remained suppressed throughout treatment. During treatment, mean estradiol decreased to the limit of detection and mean testosterone decreased but remained above prepubertal norms. During posttreatment follow-up (3.5 ± 2.2 years), all patients achieved a pubertal hormonal response within 1 year and menses were reported in all females ≥12 years old. No impairment of reproductive function was observed at adulthood (mean age: 24.8 years)
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