8,258 research outputs found
Current-voltage characteristic and stability in resonant-tunneling n-doped semiconductor superlattices
We review the occurrence of electric-field domains in doped superlattices
within a discrete drift model. A complete analysis of the construction and
stability of stationary field profiles having two domains is carried out. As a
consequence, we can provide a simple analytical estimation for the doping
density above which stable stable domains occur. This bound may be useful for
the design of superlattices exhibiting self-sustained current oscillations.
Furthermore we explain why stable domains occur in superlattices in contrast to
the usual Gunn diode.Comment: Tex file and 3 postscript figure
Oncological and clinical outcomes after conventional right hemicolectomy
Purpose:
Complete mesocolic excision (CME) has been proposed for better local control of colon cancer and to improve cancer-specific survival (CSS). However, CME may be associated with increased morbidity from bleeding during central vascular ligation. This study aimed to investigate the outcome of conventional right hemicolectomy, a traditional anatomical dissection along anatomical planes with radical excision of the central lymph nodes at the level of the origin of colic artery but without exposure of superior mesenteric vein and artery (SMV/SMA).
Method:
This was a retrospective review of a cohort of all elective right hemicolectomies performed at a specialist tertiary unit during a five-year period (2011â2015).
Results:
Five-hundred-nineteen patients (271 female, a median age of 73.0 years (interquartile range (IQR) 65.0â80.0)) were included (Stage I disease: 2.7%, stage II: 53.2%, stage III: 33.3%, stage IV: 10.8%). At the latest follow-up (a median 47 months (IQR 29â67)), local recurrence occurred in 34 patients (6.6%). Three-year overall survival was 74.4% and 3-year CSS was 85.9%. Subgroup analysis for stage IâIII showed local recurrence in 6.0%, sole distant recurrence in 7.6% while 19 patients (4.1%) suffered concomitant local and distant recurrence. The anastomotic leak rate was 1.0% and perioperative bleeding occurred in 1.2%.
Conclusions:
Oncological outcomes comparable to those of CME can be achieved by conventional surgery but with low rates of bleeding complications and anastomotic leakage. The proposed advantages of CME should be carefully considered and balanced against patientsâ co-morbidities and potential complications
APPARATUS, SYSTEMS, AND METHODS FOR MODULAR SOFT ROBOTS
Apparatus, Systems, and methods for providing modular soft robots are disclosed. In particular, the disclosed modular soft robot can include a flexible actuator having a plurality of molded flexible units. Each molded flexible unit can include a mechanical connector configured to provide a physical coupling to another molded flexible unit, and the plurality of molded flexible units are arranged to form an embedded fluidic channel. The modular soft robot can also include an inlet coupled to the embedded fluidic channel, where the inlet is configured to receive pressurized or depressurized fluid to inflate or deflate a portion of the flexible actuator, thereby causing an actuation of the flexible actuator
APPARATUS, SYSTEMS, AND METHODS FOR MODULAR SOFT ROBOTS
Apparatus, Systems, and methods for providing modular soft robots are disclosed. In particular, the disclosed modular soft robot can include a flexible actuator having a plurality of molded flexible units. Each molded flexible unit can include a mechanical connector configured to provide a physical coupling to another molded flexible unit, and the plurality of molded flexible units are arranged to form an embedded fluidic channel. The modular soft robot can also include an inlet coupled to the embedded fluidic channel, where the inlet is configured to receive pressurized or depressurized fluid to inflate or deflate a portion of the flexible actuator, thereby causing an actuation of the flexible actuator
Optically Thick Radio Cores of Narrow-Waist Bipolar Nebulae
We report our search for optically thick radio cores in sixteen narrow-waist
bipolar nebulae. Optically thick cores are a characteristic signature of
collimated ionized winds. Eleven northern nebulae were observed with the Very
Large Array (VLA) at 1.3 cm and 0.7 cm, and five southern nebulae were observed
with the Australia Telescope Compact Array (ATCA) at 6 cm and 3.6 cm. Two
northern objects, 19W32 and M 1-91, and three southern objects, He 2-25, He
2-84 and Mz 3, were found to exhibit a compact radio core with a rising
spectrum consistent with an ionized jet. Such jets have been seen in M 2-9 and
may be responsible for shaping bipolar structure in planetary nebulae.Comment: 29 pages, accepted for publication in Ap
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Camouflage and Display for Soft Machines
Synthetic systems cannot easily mimic the color-changing abilities of animals such as cephalopods. Soft machinesâmachines fabricated from soft polymers and flexible reinforcing sheetsâare rapidly increasing in functionality. This manuscript describes simple microfluidic networks that can change the color, contrast, pattern, apparent shape, luminescence, and surface temperature of soft machines for camouflage and display. The color of these microfluidic networks can be changed simultaneously in the visible and infraredâa capability that organisms do not have. These strategies begin to imitate the functions, although not the anatomies, of color-changing animals.Chemistry and Chemical Biolog
Signature of the matching field in Bose-glass melting of untwinned YBa_2Cu_3O_(7-ÎŽ) single crystals
We map out the phase boundary separating the Bose-glass and vortex-liquid phases in an irradiated twin-free YBa_2Cu_3O_(7-ÎŽ) single crystal. We take the phase boundary to be the temperature T_g and magnetic field H at which the crystal begins to screen a small ac magnetic field, h_(ac). There is a significant change in slope dT_g/dH of the phase boundary at the matching field B_Ίâ(â0.5âT) indicating that interstitial vortices significantly weaken pinning in the Bose-glass state. There is also a pronounced peak in the slope dT_g/dH just below B_Ί at higher h_(ac). Both features disappear when the field is tilted away from the columns
First order phase transition of the vortex lattice in twinned YBa2Cu3O7 single crystals in tilted magnetic fields
We present an exhaustive analysis of transport measurements performed in
twinned YBa2Cu3O7 single crystals which stablishes that the vortex solid-liquid
transition is first order when the magnetic field H is applied at an angle
theta away from the direction of the twin planes. We show that the resistive
transitions are hysteretic and the V-I curves are non-linear, displaying a
characteristic s-shape at the melting line Hm(T), which scales as
epsilon(theta)Hm(T,theta). These features are gradually lost when the critical
point H*(theta) is approached. Above H*(theta) the V-I characteristics show a
linear response in the experimentally accessible V-I window, and the transition
becomes reversible. Finally we show that the first order phase transition takes
place between a highly correlated vortex liquid in the field direction and a
solid state of unknown symmetry. As a consequence, the available data support
the scenario for a vortex-line melting rather than a vortex sublimation as
recently suggested [T.Sasagawa et al. PRL 80, 4297 (1998)].Comment: 10 pages, 8 figures, submitted to PR
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