288 research outputs found
Algebraic approach to the Hulthen potential
In this paper the energy eigenvalues and the corresponding eigenfunctions are
calculated for Hulthen potential. Then we obtain the ladder operators and show
that these operators satisfy SU(2) commutation relation.Comment: 8 Pages, 1 Tabl
Design of a freeform two-reflector system to collimate and shape a point source distribution
In this paper we propose a method to compute a freeform reflector system for
collimating and shaping a beam from a point source. We construct these
reflectors such that the radiant intensity of the source is converted into a
desired target. An important generalization in our approach compared to
previous research is that the output beam can be in an arbitrary direction. The
design problem is approached by using a generalized Monge-Amp\`ere equation.
This equation is solved using a least-squares algorithm for non-quadratic cost
functions. This algorithm calculates the optical map, from which we can then
compute the surfaces. We test our algorithm on two cases. First we consider a
uniform source and target distribution. Next, we use the model of a laser diode
light source and a ring-shaped target distribution
Measurement of the local Jahn-Teller distortion in LaMnO_3.006
The atomic pair distribution function (PDF) of stoichiometric LaMnO_3 has
been measured. This has been fit with a structural model to extract the local
Jahn-Teller distortion for an ideal Mn(3+)O_6 octahedron. These results are
compared to Rietveld refinements of the same data which give the average
structure. Since the local structure is being measured in the PDF there is no
assumption of long-range orbital order and the real, local, Jahn-Teller
distortion is measured directly. We find good agreement both with published
crystallographic results and our own Rietveld refinements suggesting that in an
accurately stoichiometric material there is long range orbital order as
expected. The local Jahn-Teller distortion has 2 short, 2 medium and 2 long
bonds.Comment: 5 pages, 3 postscript figures, minor change
Major obstetric hemorrhage: a follow-up survey on quality of life of women and their partners
Nanosized Sodium-Doped Lanthanum Manganites: Role of the Synthetic Route on their Physical Properties
In this paper we present the results of the synthesis and characterisation of
nanocrystalline La1-xNaxMnO3+delta samples. Two synthetic routes were employed:
polyacrylamide-based sol-gel and propellant synthesis. Pure, single phase
materials were obtained with grain size around 35 nm for the sol-gel samples
and around 55 nm for the propellant ones, which moreover present a more broaden
grain size distribution. For both series a superparamagnetic behaviour was
evidenced by means of magnetisation and EPR measurements with peculiar features
ascribable to the different grain sizes and morphology. Preliminary
magnetoresistivity measurements show enhanced low-field (< 1 T)
magnetoresistance values which suggest an interesting applicative use of these
manganites.Comment: 31 Pages 10 Figures to appear in Chem. Mate
A Minimum of Three Motifs Is Essential for Optimal Binding of Pseudomurein Cell Wall-Binding Domain of Methanothermobacter thermautotrophicus
We have biochemically and functionally characterized the pseudomurein cell wall-binding (PMB) domain that is present at the C-terminus of the Surface (S)-layer protein MTH719 from Methanothermobacter thermautotrophicus. Chemical denaturation of the protein with guanidinium hydrochloride occurred at 3.8 M. A PMB-GFP fusion protein not only binds to intact pseudomurein of methanogenic archaea, but also to spheroplasts of lysozyme-treated bacterial cells. This binding is pH dependent. At least two of the three motifs that are present in the domain are necessary for binding. Limited proteolysis revealed a possible cleavage site in the spacing sequence between motifs 1 and 2 of the PMB domain, indicating that the motif region itself is protected from proteases
Spin-wave scattering at low temperatures in manganite films
The temperature and magnetic field dependence of the resistivity
has been measured for LaSrMnO (y=0 and 0.128)
films grown on (100) SrTiO substrates. The low-temperature in the
ferromagnetic metallic region follows well with being the residual resistivity. We attribute the second and third term to
small-polaron and spin-wave scattering, respectively. Our analysis based on
these scattering mechanisms also gives the observed difference between the
metal-insulator transition temperatures of the films studied. Transport
measurements in applied magnetic field further indicate that spin-wave
scattering is a key transport mechanism at low temperatures.Comment: 5 pages, 4 figures. to appear in Phys. Rev.
Randomised trial of a decision aid and its timing for women being tested for a BRCA1/2 mutation
Contains fulltext :
57882.pdf (publisher's version ) (Closed access)The aim of the study was to evaluate the impact of a decision aid (DA) and its timing in women being tested for a BRCA1/2 mutation. Women with and without a previous history of cancer were included after blood sampling for genetic testing. The DA consisted of a brochure and video providing information on screening and prophylactic surgery. To evaluate the impact of the DA, women were randomised to the DA group (n=184), receiving the DA 2 weeks after blood sampling, or to the control group (n=184). To evaluate the impact of timing, mutation carriers who had received the DA before the test result (n=47) were compared to mutation carriers who received the DA after the test result (n=42). Data were collected on well-being, treatment choice, decision and information related outcomes. The impact of the DA was measured 4 weeks after blood sampling. The impact of timing was measured 2 weeks after a positive test result. The DA had no impact on well-being. Regarding decision related outcomes, the DA group more frequently considered prophylactic surgery (P=0.02) corroborated with higher valuations (P=0.04). No differences were found for the other decision related outcomes. Regarding information related outcomes, the DA group felt better informed (P=0.00), was more satisfied with the information (P=0.00), and showed more accurate risk perceptions. Timing of the DA had no effect on any of the outcomes. No interactions were found between the DA and history of cancer. In conclusion, women being tested for a BRCA1/2 mutation benefit from the DA on information related outcomes. Because timing had no effect, the DA is considered useful either before or after the test result
Strain effect on electronic transport and ferromagnetic transition temperature in LaSrMnO thin films
We report on a systematic study of strain effects on the transport properties
and the ferromagnetic transition temperature of high-quality
LaSrMnO thin films epitaxially grown on (100) SrTiO
substrates. Both the magnetization and the resistivity are critically dependent
on the film thickness. is enhanced with decreasing the film thickness
due to the compressive stain produced by lattice mismatch. The resistivity
above 165 K of the films with various thicknesses is consistent with small
polaronic hopping conductivity. The polaronic formation energy is
reduced with the decrease of film thickness. We found that the strain
dependence of mainly results from the strain-induced electron-phonon
coupling. The strain effect on is in good agreement with the
theoretical predictions.Comment: 6 pages and 5 figures, accepted for publication in Phys. Rev.
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