26 research outputs found
Low-Frequency 1/f Noise in MoS2 Thin-Film Transistors: Comparison of Single and Multilayer Structures
We report on the transport and low-frequency noise measurements of MoS2
thin-film transistors with "thin" (2-3 atomic layers) and "thick" (15-18 atomic
layers) channels. The back-gated transistors made with the relatively thick
MoS2 channels have advantages of the higher electron mobility and lower noise
level. The normalized noise spectral density of the low-frequency 1/f noise in
"thick" MoS2 transistors is of the same level as that in graphene. The MoS2
transistors with the atomically thin channels have substantially higher noise
levels. It was established that, unlike in graphene devices, the noise
characteristics of MoS2 transistors with "thick" channels (15-18 atomic planes)
could be described by the McWhorter model. Our results indicate that the
channel thickness optimization is crucial for practical applications of MoS2
thin-film transistors.Comment: 12 pages, 3 figure
Mastectomy rates are decreasing in the era of service screening: a population-based study in Italy (1997–2001)
We enrolled all 2162 in situ and 21 148 invasive cases of breast cancer in 17 areas of Italy, diagnosed in 1997–2001. Rates of early cancer increased by 13.7% in the screening age group (50–69 years), and breast conserving surgery by 24.6%. Advanced cancer rates decreased by 19.4%, and mastectomy rates by 24.2%. Service screening did not increase mastectomy rates in the study population
New insights into perinatal testicular torsion
Perinatal testicular torsion is a relatively rare event that remains unrecognized in many patients or is suspected and treated accordingly only after an avoidable loss of time. The authors report their own experience with several patients, some of them quite atypical but instructive. Missed bilateral torsion is an issue, as are partial torsion, possible antenatal signs, and late presentation. These data are discussed together with the existing literature and may help shed new light on the natural course of testicular torsion and its treatment. The most important conclusion is that a much higher index of suspicion based on clinical findings is needed for timely detection of perinatal torsion. It is the authors’ opinion that immediate surgery is mandatory not only in suspected bilateral torsions but also in cases of possible unilateral torsions. There is no place for a more fatalistic “wait-and-see” approach. Whenever possible, even necrotic testes should not be removed during surgery because some endocrine function may be retained
Zone-Folded Phonons and the Commensurate–Incommensurate Charge-Density-Wave Transition in 1<i>T</i>‑TaSe<sub>2</sub> Thin Films
Bulk 1<i>T</i>-TaSe<sub>2</sub> exhibits unusually high charge density wave (CDW) transition
temperatures of 600 and 473 K below which the material exists in the
incommensurate (I-CDW) and the commensurate (C-CDW) charge-density-wave
phases, respectively. The (13)<sup>1/2</sup> × (13)<sup>1/2</sup> C-CDW reconstruction of the lattice coincides with new Raman peaks
resulting from zone-folding of phonon modes from middle regions of
the original Brillouin zone back to Γ. The C-CDW transition
temperatures as a function of film thickness are determined from the
evolution of these new Raman peaks, and they are found to decrease
from 473 to 413 K as the film thicknesses decrease from 150 to 35
nm. A comparison of the Raman data with <i>ab initio</i> calculations of both the normal and C-CDW phases gives a consistent
picture of the zone-folding of the phonon modes following lattice
reconstruction. The Raman peak at ∼154 cm<sup>−1</sup> originates from the zone-folded phonons in the C-CDW phase. In the
I-CDW phase, the loss of translational symmetry coincides with a strong
suppression and broadening of the Raman peaks. The observed change
in the C-CDW transition temperature is consistent with total energy
calculations of bulk and monolayer 1<i>T</i>-TaSe<sub>2</sub>