1,134 research outputs found
On the Theory of Magnetotransport in a Periodically Modulated Two-Dimensional Electron Gas
A semiclassical theory based on the Boltzmann transport equation for a
two-dimensional electron gas modulated along one direction with weak
electrostatic or magnetic modulations is proposed. It is shown that
oscillations of the magnetoresistivity corresponding to the
current driven along the modulation lines observed at moderately low magnetic
fields, can be explained as classical geometric resonances reflecting the
commensurability of the period of spatial modulations and the cyclotron radius
of electrons.Comment: 5 pages, 1 figure, text and 1 figure adde
Local Flattening of the Fermi Surface and Quantum Oscillations in the Magnetoacoustic Response of a Metal
In the present work we theoretically analyze the effect of the Fermi surface
local geometry on quantum oscillations in the velocity of an acoustic wave
travelling in metal across a strong magnetic field. We show that local
flattenings of the Fermi surface could cause significant amplification of
quantum oscillations. This occurs due to enhancement of commensurability
oscillations modulating the quantum oscillations in the electron density of
states on the Fermi surface. The amplification in the quantum oscillations
could be revealed at fitting directions of the magnetic field.Comment: 4 pages, 1 figure, text adde
Weiss Oscillations in Surface Acoustic Wave Propagation
The interaction of a surface acoustic wave (SAW) with a a two-dimensional
electron gas in a periodic electric potential and a classical magnetic field is
considered. We calculate the attenuation of the SAW and its velocity change and
show that these quantities exhibit Weiss oscillations.Comment: 4 pages REVTEX, 2 figures included as eps file
A Phase I trial of talazoparib in patients with advanced hematologic malignancies
Aim: The objective of this study was to establish the maximum tolerated dose (MTD), safety, pharmacokinetics, and anti-leukemic activity of talazoparib. Patients & methods: This Phase I, two-cohort, dose-escalation trial evaluated talazoparib monotherapy in advanced hematologic malignancies (cohort 1: acute myeloid leukemia/myelodysplastic syndrome; cohort 2: chronic lymphocytic leukemia/mantle cell lymphoma). Results: Thirty-three (cohort 1: n = 25; cohort 2: n = 8) patients received talazoparib (0.1-2.0 mg once daily). The MTD was exceeded at 2.0 mg/day in cohort 1 and at 0.9 mg/day in cohort 2. Grade ≥3 adverse events were primarily hematologic. Eighteen (54.5%) patients reported stable disease. Conclusion: Talazoparib is relatively well tolerated in hematologic malignancies, with a similar MTD as in solid tumors, and shows preliminary anti leukemic activity.Clinical trial registration: NCT01399840 (ClinicalTrials.gov)
Living with a diagnosis of behavioural-variant frontotemporal dementia: The person’s experience.
YesResearch investigating behavioural-variant frontotemporal dementia has concentrated on identifying and quantifying people’s difficulties; yet few studies have considered how people with behavioural-variant frontotemporal dementia make sense of their difficulties. Five participants were interviewed and interpretive phenomenological analysis used to analyse the data. Two superordinate themes emerged: ‘Bewilderment’ and ‘Relationships with others’. ‘Bewilderment’ reflected the feelings of the participants from the start of their dementia, and was divided into two main themes (1) ‘Awareness of change: What’s the problem? and (2) Threats to self: This is not me. The superordinate theme, ‘Relationships with others’, reflected difficulties with social relationships and comprised two main themes (1) ‘Family and friends: Things haven’t changed… but do I say anything wrong?’ and (2) Coping with threats to self: Blame others or just avoid them. The themes were discussed in relation to literature evaluating the difficulties associated with behavioural-variant frontotemporal dementia together with implications for clinical practice
Planar cyclotron motion in unidirectional superlattices defined by strong magnetic and electric fields: Traces of classical orbits in the energy spectrum
We compare the quantum and the classical description of the two-dimensional
motion of electrons subjected to a perpendicular magnetic field and a
one-dimensional lateral superlattice defined by spatially periodic magnetic and
electric fields of large amplitudes. We explain in detail the complicated
energy spectra, consisting of superimposed branches of strong and of weak
dispersion, by the correspondence between the respective eigenstates and the
``channeled'' and ``drifting'' orbits of the classical description.Comment: 11 pages, 11 figures, to appear in Physical Review
Magnetoresistance of a two-dimensional electron gas with spatially periodic lateral modulations: Exact consequences of Boltzmann's equation
On the basis of Boltzmann's equation, and including anisotropic scattering in
the collision operator, we investigate the effect of one-dimensional
superlattices on two-dimensional electron systems. In addition to superlattices
defined by static electric and magnetic fields, we consider mobility
superlattices describing a spatially modulated density of scattering centers.
We prove that magnetic and electric superlattices in -direction affect only
the resistivity component if the mobility is homogeneous, whereas a
mobility lattice in -direction in the absence of electric and magnetic
modulations affects only . Solving Boltzmann's equation numerically,
we calculate the positive magnetoresistance in weak magnetic fields and the
Weiss oscillations in stronger fields within a unified approach.Comment: submitted to PR
Results from the DELCODE study
Previous studies have demonstrated increased tau plasma levels in patients
with Alzheimer’s disease (AD) and mild cognitive impairment (MCI) due to AD.
Much less is known whether increased tau plasma levels can already be detected
in the pre-MCI stage of subjective cognitive decline (SCD). In the present
study we measured tau plasma levels in 111 SCD patients and 134 age- and
gender-matched cognitively healthy controls participating in the DZNE (German
Center for Neurodegenerative Diseases) longitudinal study on cognition and
dementia (DELCODE). Tau plasma levels were measured using ultra-sensitive,
single-molecule array (Simoa) technology. We found no significant different
tau plasma levels in SCD (3.4 pg/ml) compared with healthy controls (3.6
pg/ml) after controlling for age, gender, and education (p = 0.137). In
addition, tau plasma levels did not correlate with Aβ42 (r = 0.073; p =
0.634), tau (r = −0.179; p = 0.240), and p-tau181 (r = −0.208; p = 0.171)
cerebrospinal fluid (CSF) levels in a subgroup of 45 SCD patients with
available CSF. In conclusion, plasma tau is not increased in SCD patients. In
addition, the lack of correlation between tau in plasma and CSF in the
examined cohort suggests that tau levels are affected by different factors in
both biofluids
Results from the DELCODE study
Previous studies have demonstrated increased tau plasma levels in patients
with Alzheimer’s disease (AD) and mild cognitive impairment (MCI) due to AD.
Much less is known whether increased tau plasma levels can already be detected
in the pre-MCI stage of subjective cognitive decline (SCD). In the present
study we measured tau plasma levels in 111 SCD patients and 134 age- and
gender-matched cognitively healthy controls participating in the DZNE (German
Center for Neurodegenerative Diseases) longitudinal study on cognition and
dementia (DELCODE). Tau plasma levels were measured using ultra-sensitive,
single-molecule array (Simoa) technology. We found no significant different
tau plasma levels in SCD (3.4 pg/ml) compared with healthy controls (3.6
pg/ml) after controlling for age, gender, and education (p = 0.137). In
addition, tau plasma levels did not correlate with Aβ42 (r = 0.073; p =
0.634), tau (r = −0.179; p = 0.240), and p-tau181 (r = −0.208; p = 0.171)
cerebrospinal fluid (CSF) levels in a subgroup of 45 SCD patients with
available CSF. In conclusion, plasma tau is not increased in SCD patients. In
addition, the lack of correlation between tau in plasma and CSF in the
examined cohort suggests that tau levels are affected by different factors in
both biofluids
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