8,096 research outputs found
Computer program to assess impact of fatigue and fracture criteria on weight and cost of transport aircraft
A preliminary design analysis tool for rapidly performing trade-off studies involving fatigue, fracture, static strength, weight, and cost is presented. Analysis subprograms were developed for fatigue life, crack growth life, and residual strength; and linked to a structural synthesis module which in turn was integrated into a computer program. The part definition module of a cost and weight analysis program was expanded to be compatible with the upgraded structural synthesis capability. The resultant vehicle design and evaluation program is named VDEP-2. It is an accurate and useful tool for estimating purposes at the preliminary design stage of airframe development. A sample case along with an explanation of program applications and input preparation is presented
Off-diagonal hyperfine interaction between the 6p1/2 and 6p3/2 levels in 133Cs
The off-diagonal hyperfine interaction between the 6p1/2 and 6p3/2 states in
133Cs is evaluated in third-order MBPT giving 37.3 Hz and 48.3 Hz,
respectively, for second-order energies of the 6p3/2 F=3 and F=4 levels. This
result is a factor of 10 smaller than one obtained from an uncorrelated
first-order Dirac-Hartree-Fock calculation and used in the analysis of a recent
high-precision (< 2 kHz) measurement of the 6p3/2 hyperfine structure [Gerginov
et al. Phys. Rev. Lett. 91, 72301 (2003)]. The factor of 10 difference has
negligible effect on the conclusions of the recent experiment but will become
important for experiments carried out at a precision of better than 1 kHz
Bulk Fermi surface and electronic properties of CuBiSe
The electronic properties of CuBiSe have been
investigated using Shubnikov-de Haas and optical reflectance measurements.
Quantum oscillations reveal a bulk, three-dimensional Fermi surface with
anisotropy 2 and a modest increase in
free-carrier concentration and in scattering rate with respect to the undoped
BiSe, also confirmed by reflectivity data. The effective mass is
almost identical to that of BiSe. Optical conductivity reveals a
strong enhancement of the bound impurity bands with Cu addition, suggesting
that a significant number of Cu atoms enter the interstitial sites between Bi
and Se layers or may even substitute for Bi. This conclusion is also supported
by X-ray diffraction measurements, where a significant increase of microstrain
was found in CuBiSe, compared to BiSe.Comment: Accepted to Phys. Rev B (R
Investigation of infrared phonon modes in multiferroic single-crystal FeTeOBr
Reflection and transmission as a function of temperature (5--300 K) have been
measured on single crystals of the multiferroic compound FeTeOBr
utilizing light spanning the far infrared to the visible portions of the
electromagnetic spectrum. The complex dielectric function and optical
properties were obtained via Kramers-Kronig analysis and by fits to a
Drude-Lortentz model. Analysis of the anisotropic excitation spectra via
Drude-Lorentz fitting and lattice dynamical calculations have lead to the
observation of all 52 IR-active modes predicted in the plane and 43 or the
53 modes predicted along the b axis of the monoclinic cell. Assignments to
groups (clusters) of phonons have been made and trends within them are
discussed in light of our calculated displacement patterns.Comment: 9 pages, 7 figure
Classical Coulomb three-body problem in collinear eZe configuration
Classical dynamics of two-electron atom and ions H, He, Li,
Be,... in collinear eZe configuration is investigated. It is revealed
that the mass ratio between necleus and electron plays an important role
for dynamical behaviour of these systems. With the aid of analytical tool and
numeircal computation, it is shown that thanks to large mass ratio ,
classical dynamics of these systems is fully chaotic, probably hyperbolic.
Experimental manifestation of this finding is also proposed.Comment: Largely rewritten. 21 pages. All figures are available in
http://ace.phys.h.kyoto-u.ac.jp/~sano/3-body/index.htm
Unusual Shubnikov-de Haas oscillations in BiTeCl
We report measurements of Shubnikov-de Haas (SdH) oscillations in single
crystals of BiTeCl at magnetic fields up to 31 T and at temperatures as low as
0.4 K. Two oscillation frequencies were resolved at the lowest temperatures,
Tesla and Tesla. We also measured the
infrared optical reflectance and Hall effect; we
propose that the two frequencies correspond respectively to the inner and outer
Fermi sheets of the Rashba spin-split bulk conduction band. The bulk carrier
concentration was cm and the effective
masses for the inner and for the
outer sheet. Surprisingly, despite its low effective mass, we found that the
amplitude of is very rapidly suppressed with increasing temperature,
being almost undetectable above K
Foci of Schistosomiasis mekongi, Northern Cambodia: II. Distribution of infection and morbidity.
In the province of Kracheh, in Northern Cambodia, a baseline epidemiological survey on Schistosoma mekongi was conducted along the Mekong River between December 1994 and April 1995. The results of household surveys of highly affected villages of the East and the West bank of the river and of school surveys in 20 primary schools are presented. In household surveys 1396 people were examined. An overall prevalence of infection of 49.3% was detected by a single stool examination with the Kato-Katz technique. The overall intensity of infection was 118.2 eggs per gram of stool (epg). There was no difference between the population of the east and west shore of the Mekong for prevalence (P = 0.3) or intensity (P = 0.9) of infection. Severe morbidity was very frequent. Hepatomegaly of the left lobe was detected in 48.7% of the population. Splenomegaly was seen in 26.8% of the study participants. Visible diverted circulation was found in 7.2% of the population, and ascites in 0.1%. Significantly more hepatomegaly (P = 0.001), splenomegaly (P = 0. 001) and patients with diverted circulation (P = 0.001) were present on the west bank of the Mekong. The age group of 10-14 years was most affected. The prevalence of infection in this group was 71.8% and 71.9% in the population of the West and East of the Mekong, respectively. The intensity of infection was 172.4 and 194.2 epg on the West and the East bank, respectively. In the peak age group hepatomegaly reached a prevalence of 88.1% on the west and 82.8% on the east bank. In the 20 schools 2391 children aged 6-16 years were examined. The overall prevalence of infection was 40.0%, ranging from 7.7% to 72.9% per school. The overalls mean intensity of infection was 110.1 epg (range by school: 26.7-187.5 epg). Both prevalence (P = 0.001) and intensity of infection (P = 0.001) were significantly higher in schools on the east side of the Mekong. Hepatomegaly (55.2%), splenomegaly (23.6%), diverted circulation (4. 1%), ascites (0.5%), reported blood (26.7%) and mucus (24.3%) were very frequent. Hepatomegaly (P = 0.001), splenomegaly (P = 0.001), diverted circulation (P = 0.001) and blood in stool (P = 0.001) were significantly more frequent in schools of the east side of the Mekong. Boys suffered more frequently from splenomegaly (P = 0.05), ascites (P = 0.05) and bloody stools (P = 0.004) than girls. No difference in sex was found for the prevalence and intensity of infection and prevalence of hepatomegaly. On the school level prevalence and intensity of infection were highly associated (r = 0. 93, P = 0.0001). The intensity of infection was significantly associated only with the prevalence of hepatomegaly (r = 0.44, P = 0. 05) and blood in stool (r = 0.40, P = 0.02). This comprehensive epidemiological study documents for the first time the public health importance of schistosomiasis mekongi in the Province of Kracheh, Northern Cambodia and points at key epidemiological features of this schistosome species, in particular the high level of morbidity associated with infection
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