5,403 research outputs found
On wavenumber spectra for sound within subsonic jets
This paper clarifies the nature of sound spectra within subsonic jets. Three
problems, of increasing complexity, are presented. Firstly, a point source is
placed in a two-dimensional plug flow and the sound field is obtained
analytically. Secondly, a point source is embedded in a diverging axisymmetric
jet and the sound field is obtained by solving the linearised Euler equations.
Finally, an analysis of the acoustic waves propagating through a turbulent jet
obtained by direct numerical simulation is presented. In each problem, the
pressure or density field are analysed in the frequency-wavenumber domain. It
is found that acoustic waves can be classified into three main
frequency-dependent groups. A physical justification is provided for this
classification. The main conclusion is that, at low Strouhal numbers, acoustic
waves satisfy the d'Alembertian dispersion relation.Comment: 20 pages, 9 figure
Etch Induced Microwave Losses in Titanium Nitride Superconducting Resonators
We have investigated the correlation between the microwave loss and
patterning method for coplanar waveguide titanium nitride resonators fabricated
on Si wafers. Three different methods were investigated: fluorine- and
chlorine-based reactive ion etches and an argon-ion mill. At high microwave
probe powers the reactive etched resonators showed low internal loss, whereas
the ion-milled samples showed dramatically higher loss. At single-photon powers
we found that the fluorine-etched resonators exhibited substantially lower loss
than the chlorine-etched ones. We interpret the results by use of numerically
calculated filling factors and find that the silicon surface exhibits a higher
loss when chlorine-etched than when fluorine-etched. We also find from
microscopy that re-deposition of silicon onto the photoresist and side walls is
the probable cause for the high loss observed for the ion-milled resonator
Subtotal pancreatectomy for cancer: closure of the pancreatic remnant with staplers
This paper presents a 2-year series of 26 consecutive pancreatectomies for periampullary cancer where the pancreatic tail was closed with a stapler in order to avoid complications related to a pancreatico-digestive anastomosis. The follow-up period was 14 months or more. Seven patients developed operative complications. Pancreatic fistulas developed in 3 patients. The fistulas closed spontaneously in 2 of the patients after 2-4 months. Intraabdominal abscesses developed in 4 patients and required surgical drainage. In 1 of these patients, the abscess eroded a large vessel with a fatal outcome resulting in an operative mortality rate of 3.8%. A transient postoperative gastric stasis was observed in seven patients. Postoperative hospital median stay was 27 days (range 10-83 days). Eighteen patients have died after 4-30 months in recurrent disease and seven patients are alive after a follow-up period of 15-29 months. Pancreatic endocrine function seemed well preserved; diabetes mellitus has developed in only one patient. In conclusion, it appears that subtotal pancreatectomy with closure of the pancreatic remnant with staples gives a low morbidity and mortality. Although the conclusion should be tempered by the small number of patients, the results justify continued evaluation of this technique with long-term follow-up
Coherence in a transmon qubit with epitaxial tunnel junctions
We developed transmon qubits based on epitaxial tunnel junctions and
interdigitated capacitors. This multileveled qubit, patterned by use of
all-optical lithography, is a step towards scalable qubits with a high
integration density. The relaxation time T1 is .72-.86mu sec and the ensemble
dephasing time T2 is slightly larger than T1. The dephasing time T2 (1.36mu
sec) is nearly energy-relaxation-limited. Qubit spectroscopy yields weaker
level splitting than observed in qubits with amorphous barriers in
equivalent-size junctions. The qubit's inferred microwave loss closely matches
the weighted losses of the individual elements (junction, wiring dielectric,
and interdigitated capacitor), determined by independent resonator
measurements
Synchronizing automata with random inputs
We study the problem of synchronization of automata with random inputs. We
present a series of automata such that the expected number of steps until
synchronization is exponential in the number of states. At the same time, we
show that the expected number of letters to synchronize any pair of the famous
Cerny automata is at most cubic in the number of states
The G292.0+1.8 pulsar wind nebula in the mid-infrared
G292.0+1.8 is a Cas A-like supernova remnant that contains the young pulsar
PSR J1124-5916 powering a compact torus-like pulsar wind nebula visible in
X-rays. A likely counterpart to the nebula has been detected in the optical VRI
bands. To confirm the counterpart candidate nature, we examined archival
mid-infrared data obtained with the Spitzer Space Telescope. Broad-band images
taken at 4.5, 8, 24, and 70 microns were analyzed and compared with available
optical and X-ray data. The extended counterpart candidate is firmly detected
in the 4.5 and 8 micron bands. It is brighter and more extended in the bands
than in the optical, and its position and morphology agree well with the
coordinates and morphology of the torus-like pulsar wind nebula in X-rays. The
source is not visible in 24 and 70 micron images, which are dominated by bright
emission from the remnant shell and filaments. We compiled the infrared fluxes
of the nebula, which probably contains a contribution from an unresolved pulsar
in its center, with the optical and X-ray data. The resulting unabsorbed
multiwavelength spectrum is described by power laws of significantly steeper
slope in the infrared-optical than in X-rays, implying a double-knee spectral
break between the optical and X-rays. The 24 and 70 microns flux upper limits
suggest a second break and a flatter spectrum at the long wavelength limit.
These features are common to two other pulsar wind nebulae associated with the
remnants B0540-69.3 and 3C 58 and observed in all three ranges. The position,
morphology, and spectral properties of the detected source allow us to comfirm
that it is the infrared-optical counterpart to both the pulsar and its wind
nebula system in the G292.0+1.8 supernova remnant.Comment: 5 pages, 2 figure
Projected long-term outcomes in patients with type 1 diabetes treated with fast-acting insulin aspart versus conventional insulin aspart in the UK setting
Aims: Many patients with type 1 diabetes mellitus (T1DM) fail to achieve optimal glycemic control and mealtime insulins that more closely match physiological insulin secretion can help improve treatment. In the onset 1 trial, fast-acting insulin aspart (faster aspart) was shown to improve glycemic control in patients with T1DM compared with conventional insulin aspart (insulin aspart). In the UK, faster aspart and insulin aspart are associated with the same acquisition cost, and therefore the present analysis assessed the impact of faster aspart versus insulin aspart on long-term clinical outcomes and costs for patients with T1DM in the UK setting.
Methods: The QuintilesIMS CORE Diabetes Model was used to project clinical outcomes and costs over patient lifetimes in a cohort with baseline characteristics from the onset 1 trial. Treatment effects were taken from the 26-week main phase of the onset 1 trial, with costs and utilities based on literature review. Future costs and clinical benefits were discounted at 3.5% annually.
Results: Projections indicated that faster aspart was associated with improved discounted quality-adjusted life expectancy (by 0.13 quality-adjusted life years) versus insulin aspart). Improved clinical outcomes resulted from fewer diabetes-related complications and a delayed time to their onset with faster aspart. Faster aspart was found to be associated with reduced costs versus insulin aspart (cost savings of GBP 1,715), resulting from diabetes-related complications avoided and reduced treatment costs.
Conclusions: Faster aspart was associated with improved clinical outcomes and cost savings versus insulin aspart for patients with T1DM in the UK setting
Reset thresholds of automata with two cycle lengths
We present several series of synchronizing automata with multiple parameters,
generalizing previously known results. Let p and q be two arbitrary co-prime
positive integers, q > p. We describe reset thresholds of the colorings of
primitive digraphs with exactly one cycle of length p and one cycle of length
q. Also, we study reset thresholds of the colorings of primitive digraphs with
exactly one cycle of length q and two cycles of length p.Comment: 11 pages, 5 figures, submitted to CIAA 201
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