2,828 research outputs found
Predicting Alzheimer's risk: why and how?
Because the pathologic processes that underlie Alzheimer's disease (AD) appear to start 10 to 20 years before symptoms develop, there is currently intense interest in developing techniques to accurately predict which individuals are most likely to become symptomatic. Several AD risk prediction strategies - including identification of biomarkers and neuroimaging techniques and development of risk indices that combine traditional and non-traditional risk factors - are being explored. Most AD risk prediction strategies developed to date have had moderate prognostic accuracy but are limited by two key issues. First, they do not explicitly model mortality along with AD risk and, therefore, do not differentiate individuals who are likely to develop symptomatic AD prior to death from those who are likely to die of other causes. This is critically important so that any preventive treatments can be targeted to maximize the potential benefit and minimize the potential harm. Second, AD risk prediction strategies developed to date have not explored the full range of predictive variables (biomarkers, imaging, and traditional and non-traditional risk factors) over the full preclinical period (10 to 20 years). Sophisticated modeling techniques such as hidden Markov models may enable the development of a more comprehensive AD risk prediction algorithm by combining data from multiple cohorts. As the field moves forward, it will be critically important to develop techniques that simultaneously model the risk of mortality as well as the risk of AD over the full preclinical spectrum and to consider the potential harm as well as the benefit of identifying and treating high-risk older patients
Superfluid state of repulsively interacting three-component fermionic atoms in optical lattices
We investigate the superfluid state of repulsively interacting
three-component (color) fermionic atoms in optical lattices. When the
anisotropy of the three repulsive interactions is strong, atoms of two of the
three colors form Cooper pairs and atoms of the third color remain a Fermi
liquid. An effective attractive interaction is induced by density fluctuations
of the third-color atoms. This superfluid state is stable against changes in
filling close to half filling. We determine the phase diagrams in terms of
temperature, filling, and the anisotropy of the repulsive interactions.Comment: 5 pages, 6 figure
Provider Perspectives on the Influence of Family on Nursing Home Resident Transfers to the Emergency Department: Crises at the End of Life.
Background. Nursing home (NH) residents often experience burdensome and unnecessary care transitions, especially towards the end of life. This paper explores provider perspectives on the role that families play in the decision to transfer NH residents to the emergency department (ED). Methods. Multiple stakeholder focus groups (n = 35 participants) were conducted with NH nurses, NH physicians, nurse practitioners, physician assistants, NH administrators, ED nurses, ED physicians, and a hospitalist. Stakeholders described experiences and challenges with NH resident transfers to the ED. Focus group interviews were recorded and transcribed verbatim. Transcripts and field notes were analyzed using a Grounded Theory approach. Findings. Providers perceive that families often play a significant role in ED transfer decisions as they frequently react to a resident change of condition as a crisis. This sense of crisis is driven by 4 main influences: insecurities with NH care; families being unprepared for end of life; absent/inadequate advance care planning; and lack of communication and agreement within families regarding goals of care. Conclusions. Suboptimal communication and lack of access to appropriate and timely palliative care support and expertise in the NH setting may contribute to frequent ED transfers
Electric Charge in Interaction with Magnetically Charged Black Holes
We examine the angular momentum of an electric charge e placed at rest
outside a dilaton black hole with magnetic charge Q. The electromagnetic
angular momentum which is stored in the electromagnetic field outside the black
hole shows several common features regardless of the dilaton coupling strength,
though the dilaton black holes are drastically different in their spacetime
structure depending on it. First, the electromagnetic angular momentum depends
on the separation distance between the two objects and changes monotonically
from eQ to 0 as the charge goes down from infinity to the horizon, if
rotational effects of the black hole are discarded. Next, as the black hole
approaches extremality, however, the electromagnetic angular momentum tends to
be independent of the distance between the two objects. It is then precisely
as in the electric charge and monopole system in flat spacetime. We
discuss why these effects are exhibited and argue that the above features are
to hold in widely generic settings including black hole solutions in theories
with more complicated field contents, by addressing the no hair theorem for
black holes and the phenomenon of field expulsion exhibited by extremal black
holes.Comment: 26 pages, 4 figures ; Typos are corrected and a reference is adde
A tale of seven narrow spikes and a long trough: Constraining the timing of the percolation of HII bubbles at the tail end of reionization with ULAS J1120+0641
High-signal to noise observations of the Ly forest transmissivity in
the z = 7.085 QSO ULAS J1120+0641 show seven narrow transmission spikes
followed by a long 240 cMpc/h trough. Here we use radiative transfer
simulations of cosmic reionization previously calibrated to match a wider range
of Ly forest data to show that the occurrence of seven transmission
spikes in the narrow redshift range z = 5.85 - 6.1 is very sensitive to the
exact timing of reionization. Occurrence of the spikes requires the most under
dense regions of the IGM to be already fully ionised. The rapid onset of a long
trough at z = 6.12 requires a strong decrease of the photo-ionisation rate at
z6.1 in this line-of-sight, consistent with the end of percolation at
this redshift. The narrow range of reionisation histories that we previously
found to be consistent with a wider range of Ly forest data have a
reasonable probability of showing seven spikes and the mock absorption spectra
provide an excellent match to the spikes and the trough in the observed
spectrum of ULAS J1120+0641. Despite the large overall opacity of Ly at
z > 5.8, larger samples of high signal-to-noise observations of rare
transmission spikes should therefore provide important further insights into
the exact timing of the percolation of HII bubbles at the tail-end of
reionizatio
Development and Validation of eRADAR: A Tool Using EHR Data to Detect Unrecognized Dementia.
ObjectivesEarly recognition of dementia would allow patients and their families to receive care earlier in the disease process, potentially improving care management and patient outcomes, yet nearly half of patients with dementia are undiagnosed. Our aim was to develop and validate an electronic health record (EHR)-based tool to help detect patients with unrecognized dementia (EHR Risk of Alzheimer's and Dementia Assessment Rule [eRADAR]).DesignRetrospective cohort study.SettingKaiser Permanente Washington (KPWA), an integrated healthcare delivery system.ParticipantsA total of 16 665 visits among 4330 participants in the Adult Changes in Thought (ACT) study, who undergo a comprehensive process to detect and diagnose dementia every 2 years and have linked KPWA EHR data, divided into development (70%) and validation (30%) samples.MeasurementsEHR predictors included demographics, medical diagnoses, vital signs, healthcare utilization, and medications within the previous 2 years. Unrecognized dementia was defined as detection in ACT before documentation in the KPWA EHR (ie, lack of dementia or memory loss diagnosis codes or dementia medication fills).ResultsOverall, 1015 ACT visits resulted in a diagnosis of incident dementia, of which 498 (49%) were unrecognized in the KPWA EHR. The final 31-predictor model included markers of dementia-related symptoms (eg, psychosis diagnoses, antidepressant fills), healthcare utilization pattern (eg, emergency department visits), and dementia risk factors (eg, cerebrovascular disease, diabetes). Discrimination was good in the development (C statistic = .78; 95% confidence interval [CI] = .76-.81) and validation (C statistic = .81; 95% CI = .78-.84) samples, and calibration was good based on plots of predicted vs observed risk. If patients with scores in the top 5% were flagged for additional evaluation, we estimate that 1 in 6 would have dementia.ConclusionThe eRADAR tool uses existing EHR data to detect patients with good accuracy who may have unrecognized dementia. J Am Geriatr Soc 68:103-111, 2019
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Large Ly α opacity fluctuations and low CMB τ in models of late reionization with large islands of neutral hydrogen extending to z < 5.5
High-redshift QSO spectra show large spatial fluctuations in the Ly-alpha
opacity of the intergalactic medium on surprisingly large scales at z>~5.5. We
present a radiative transfer simulation of cosmic reionization driven by
galaxies that reproduces this large scatter and the rapid evolution of the
Ly-alpha opacity distribution at 5<z<6. The simulation also reproduces the low
Thomson scattering optical depth reported by the latest CMB measurement and is
consistent with the observed short near-zones and strong red damping wings in
the highest-redshift QSOs. It also matches the rapid disappearance of observed
Ly-alpha emission by galaxies at z>~6. Reionization is complete at z=5.3 in our
model, and 50% of the volume of the Universe is ionized at z=7. Agreement with
the Ly-alpha forest data in such a late reionization model requires a rapid
evolution of the ionizing emissivity of galaxies that peaks at z~6.8. The late
end of reionization results in a large scatter in the photoionisation rate and
the neutral hydrogen fraction at redshifts as low as z<~5.5 with large residual
neutral 'islands' that can produce very long Gunn-Peterson troughs resembling
those seen in the data
ABSOLUTE CONTINUITY AND HYPONORMAL OPERATORS
ABSTRACT. Let T be a completely hyponormal operator, wit
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Planting the Seed : Perceived Benefits of and Strategies for Discussing Long-Term Prognosis with Older Adults
OBJECTIVES: To characterize the goals and approaches of clinicians with experience discussing long-term prognostic information with older adults. DESIGN: We used a semistructured interview guide containing 2 domains of perceived benefits and strategies to explore why and how clinicians choose to discuss long-term prognosis, defined as life expectancy on the scale of years, with patients. SETTING: Clinicians from home-based primary care practices, community-based clinics, and academic medical centers across San Francisco. PARTICIPANTS: Fourteen physicians, including 11 geriatricians and 1 geriatric nurse practitioner, with a mean age of 40 and a mean 9 years in practice. MEASUREMENTS: Clinician responses were analyzed qualitatively using the constant comparisons approach. RESULTS: Perceived benefits of discussing long-term prognosis included establishing realistic expectations for patients, encouraging conversations about future planning, and promoting shared decision-making through understanding of patient goals of care. Communication strategies included adapting discussions to individual patient preferences and engaging in multiple conversations over time. Clinicians preferred to communicate prognosis in words and with a visual aid, although most did not know of a suitable visual aid. CONCLUSION: Engaging in customized longitudinal discussions of long-term prognosis aids clinicians in anchoring conversations about future planning and preparing patients for the end of life
Critical properties of S=1/2 Heisenberg ladders in magnetic fields
The critical properties of the Heisenberg two-leg ladders are
investigated in a magnetic field. Combining the exact diagonalization method
and the finite-size-scaling analysis based on conformal field theory, we
calculate the critical exponents of spin correlation functions numerically. For
a strong interchain coupling, magnetization dependence of the critical
exponents shows characteristic behavior depending on the sign of the interchain
coupling. We also calculate the critical exponents for the Heisenberg
two-leg ladder with a diagonal interaction, which is thought as a model
Hamiltonian of the organic spin ladder compound
. Numerical results are compared with
experimental results of temperature dependence of the NMR relaxation rate
.Comment: REVTeX, 10 pages, 8 figures, accepted for Phys. Rev.
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