Atomically-thin, inherently 2D semiconductors offer thickness scaling of nanoelectronic devices and excellent response to light for low-power versatile applications. Using small exfoliated flakes, ...advanced devices and integrated circuits have already been realized, showing great potential to impact nanoelectronics. Here, high-quality single-crystal MoSe2 is grown by molecular beam epitaxy on AlN(0001)/Si(111), showing the potential for scaling up growth to low-cost, large-area substrates for mass production. The MoSe2 layers are epitaxially aligned with the aluminum nitride (AlN) lattice, showing a uniform, smooth surface and interfaces with no reaction or intermixing, and with sufficiently high band offsets. High-quality single-layer MoSe2 is obtained, with a direct gap evidenced by angle-resolved photoemission spectroscopy and further confirmed by Raman and intense room temperature photoluminescence. The successful growth of high-quality MoSe2/Bi2Se3 multilayers on AlN shows promise for novel devices exploiting the non-trivial topological properties of Bi2Se3.
Abstract Objective Decreased processing speed (PS) is a key feature of schizophrenia with respect to cognition, functional outcome and clinical symptoms. Our objective was to test whether PS slowing ...mediates other neuropsychological deficits among patients with chronic schizophrenia. Method One hundred patients with schizophrenia and 53 healthy adults completed a series of neuropsychological measures that assess six cognitive domains. In addition to PS these included attention, verbal memory, visual memory, working memory, and executive functioning. Confirmatory factor analysis (CFA) was used to evaluate the fit of the 6-factor model. The cognitive performances of both groups were compared before and after controlling for the effect of PS, but also after controlling for the effect of each cognitive factor at a time. Finally, the PS-related variance was removed and the effect of the other cognitive factors was tested again. Results CFA supported the hypothesized 6-factor cognitive structure. As expected, the patients and controls differed on all cognitive measures. However, after controlling for the effects of PS, group differences on the other five cognitive factors decreased substantially. Controlling for other factors produced smaller attenuation of group differences, and these effects were also partially accounted for by decreased PS. Conclusions PS deficits account for most of the differences in cognition between patients with schizophrenia and healthy controls. PS slowing appears to be a core feature of schizophrenia, one that underlies impairments of working memory, executive functioning, and other abilities.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Differences in the memory characteristics of patients with Alzheimer's disease (AD), Huntington's disease (HD), and Parkinson's disease (PD) were investigated with tests that assess learning and ...retention of words, line-drawn objects, and locations. Large groups of AD, HD, and PD patients were administered the Hopkins Verbal Learning Test-Revised (HVLT-R) and the Hopkins Board (HB). Eight learning and memory measures were subjected to discriminant function analysis. A 91% classification accuracy was achieved for the separation of cortical and subcortical dementias and 79% accuracy for the discrimination of the three groups. The delayed recall of items was the best discriminator. Receiver-operating curve analysis indicated up to 90% sensitivity and 90% specificity in differentiating the three diseases using the discriminant scores. Individual learning and memory measures of the HVLT-R and the HB provided very high sensitivity and specificity in distinguishing cortical versus subcortical dementias and modest accuracy in separating the two subcortical diseases.
Background
Subjective cognitive decline (SCD) is a self-evaluation of cognitive impairment, in the absence of observed objective cognitive deficits on a neuropsychological assessment. Frailty refers ...to a multidimensional syndrome where the individual has poor health including falls, disabilities, hospitalization, and vulnerability. Both terms are associated with cognitive decline and increased incidence of dementia. The present longitudinal study explored whether the detection of SCD can predict the development of frailty over time.
Methods
The Hellenic Longitudinal Investigation of Aging and Diet (HELIAD) is an epidemiological, population-based study. From the original testing sample of 1,984 older Greek individuals (≥65 years old), 1,121 remained in the longitudinal analysis. Participants diagnosed with frailty, Mild Cognitive Impairment (MCI), dementia, severe depression, and anxiety, in the baseline assessment were excluded from the analysis (n=146), resulting in a total sample of 975 participants. The average follow-up interval was 3.1 years (SD=0.84 years). SCD was assessed in the baseline assessment with a series of eighteen questions. The questions regarding SCD were categorized according to cognitive domains. Frailty was assessed according to a phenotypic-physiologic (Fried’s definition) and a multidomain approach (Frailty Index). Univariate and multivariate Cox regression analyses were used for exploring the role of SCD in developing frailty.
Results
The proportion of individuals with frailty according to Fried’s definition was greater compared to the Frailty Index. At follow-up according to Fried’s definition, a greater proportion of cases with frailty was found in those who reported SCD complaints regarding orientation (OD) (HR=3.12 95% CI:1.45–6.73 p<0.004) or in those who reported at least three SCD complaints regarding their memory performance (SMC3) (HR=1.92 95% CI:1.05–3.52 p<0.035) at the baseline assessment. Subjective complaints regarding orientation were predictive of a greater hazard of frailty as defined by the Fried scale (HR=3.12 95% CI:1.45–6.73 p<0.004) and the Frailty Index (HR=3.59 95% CI:1.77–7.25 p<0.001).
Conclusion
Our findings demonstrate that healthy older adults who report SCD complaints regarding orientation or state that they have at least three memory complaints have a higher risk of developing frailty. Additionally, the number of participants with a clinical diagnosis of MCI or dementia, compared to individuals with normal aging, at follow-up was found to be significantly greater in cases with frailty according to both frailty definitions applied (p<0.001). Consequently, it is advisable to use screening questionnaires for SCD covering multiple cognitive domains in clinical practice for identifying and managing frailty, thus, implementing effective interventions to promote healthy aging.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Molecular beam epitaxy of 2D metal TaSe2/2D MoSe2 (HfSe2) semiconductor heterostructures on epi-AlN(0001)/Si(111) substrates is reported. Electron diffraction reveals an in-plane orientation ...indicative of van der Waals epitaxy, whereas electronic band imaging supported by first-principles calculations and X-ray photoelectron spectroscopy indicate the presence of a dominant trigonal prismatic 2H-TaSe2 phase and a minor contribution from octahedrally coordinated TaSe2, which is present in TaSe2/AlN and TaSe2/HfSe2/AlN but notably absent in the TaSe2/MoSe2/AlN, indicating superior structural quality of TaSe2 grown on MoSe2. Apart from its structural and chemical compatibility with the selenide semiconductors, TaSe2 has a workfunction of 5.5 eV as measured by ultraviolet photoelectron spectroscopy, which matches very well with the semiconductor workfunctions, implying that epi-TaSe2 can be used for low-resistivity contacts to MoSe2 and HfSe2.
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IJS, KILJ, NUK, PNG, UL, UM
The development of high electron mobility transistors (HEMTs) from AlN/GaN heterostructures, grown by plasma assisted molecular beam epitaxy has been investigated. It is shown that AlN can be grown ...fully strained on GaN, up to a thickness of 5
nm, when strain relaxation by introduction of microcracks is initiated. An optimized HEMT structure with 4.5
nm AlN barrier and 1
nm GaN cap layer exhibited a two-dimensional electron gas (2DEG) density of 3.6
×
10
13
cm
−2 along with room-temperature mobility of ∼1200
cm
2/V
s, with corresponding sheet resistance of 144
Ω/sq. The measured 2DEG density is in very good agreement with self-consistent Schrödinger–Poisson calculations for fully strained AlN layer. HEMT transistors with 1
μm gate length exhibited record-high source–drain current density of 1.8
A/mm and maximum transconductance of 400
mS/mm.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Sleep is essential to all human body functions as well as brain functions. Inadequate sleep quantity and poor sleep quality have been shown to directly affect cognitive functioning and especially ...memory. The primary aim of the present study was to investigate the association of sleep quality with cognitive abilities cross-sectionally in a middle-aged Greek population and secondarily to examine this association prospectively in a smaller group of these participants.
A total of 2112 healthy adults aged 25-70 years (mean: 46.7±11.5) from the Epirus Health Study cohort were included in the analysis and 312 of them participated in secondary prospective analysis. Sleep quality was measured by the Pittsburgh Sleep Quality Index (PSQI) scale and cognition was assessed in primary cross-sectional analyses with three neuropsychological tests, namely the Verbal Fluency test, the Logical Memory test and the Trail Making test, and in secondary prospective analyses with online versions of Posner cueing task, an emotional recognition task, the Corsi block-tapping task and the Stroop task. Statistical analysis was performed using multivariable linear regression models adjusted for age, sex, education, body mass index and alcohol consumption.
Attention/processing speed was the only cognitive domain associated cross-sectionally with PSQI score. Specifically, participants with better self-reported sleep quality performed faster on the Trail Making Test - Part A (β= 0.272 seconds, 95% CI 0.052, 0.493).
Further studies are needed to clarify the association of sleep quality with cognition, especially in middle-aged people that are still in productive working years.
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