2,411 research outputs found
The effects of radiant heat on various regions of the human body
Time sequence of perspiration and skin temperature in various regions of human body exposed to infrared radiatio
Dichotomous Hamiltonians with Unbounded Entries and Solutions of Riccati Equations
An operator Riccati equation from systems theory is considered in the case
that all entries of the associated Hamiltonian are unbounded. Using a certain
dichotomy property of the Hamiltonian and its symmetry with respect to two
different indefinite inner products, we prove the existence of nonnegative and
nonpositive solutions of the Riccati equation. Moreover, conditions for the
boundedness and uniqueness of these solutions are established.Comment: 31 pages, 3 figures; proof of uniqueness of solutions added; to
appear in Journal of Evolution Equation
Description of rotating nuclei in terms of isovector pairing
A systematic investigation of the rotating even-even nuclei in the mass
region has been performed within the frameworks of the Cranked
Relativistic Mean field, Cranked Relativistic Hartree Bogoliubov theories and
cranked Nilsson-Strutinsky approach. Most of the experimental data is well
accounted for in the calculations. The present study suggests that there is
strong isovector -pair field at low spin, the strength of which is defined
by the isospin symmetry. At high spin, the isovector pair field is destroyed
and the data are well described by the calculations assuming zero pairing. No
clear evidence for the existence of the isoscalar -pairing has been
obtained in the present investigation.Comment: 20 pages + 19 figures, submitted to Phys. Rev.
Immediate or delayed breast reconstruction after mastectomy: what do women really want
Breast reconstruction, especially immediate reconstruction after mastectomy has increased over the last decades, at present being regularly offered in many centres worldwide. Despite obvious benefits and the evident oncological safety of primary breast reconstruction, the majority of women still receive a delayed procedure or even no reconstructive surgery. The objective of the present study was to determine the preference of women for breast reconstructionâimmediate or delayedâand in the case of rejection of treatment to find out the reasons for this reluctance. In a prospective study a sample of 200 womenâdivided into two groupsâwere evaluated by an oral interview on the subject. The two-formed groups of participants consisted of randomly chosen women (n=100) and non-surgical nurses (n=100). The questionnaire surveyed personal data including marital status and educational level, as well as information about the preferred timing, the method of and the reasons for or against breast reconstruction. The evaluation of all data showed that 66% of the participants voted for additional surgery after mastectomy. Young age and high education level were significantly correlated (age r=0.56, P<0.01; education r=0.25, P<0.01) to the wish for reconstruction. The mean age of all participants was 39years (range 20-69), with a significant difference between the two groups (P<0.01), the group of nurses being younger (mean age 35, range 20-62) and the other women being older (mean age 43, range 20-69). Concerning the timing of reconstruction, 21% of women elected to have an immediate and 27% a delayed operation. Yet, 52% could not come to a decision as to whether they should prefer a primary or secondary procedure. For the surgical procedureâautologous versus non-autologous tissueâabout 23% of the participants could not decide spontaneously, while 40% preferred autologous tissue, 14% implants and 23% would choose a combination of both. The main reason in favour of reconstruction was that it would enhance the physical appearance (96%), whereas an important reason for general rejection was the fear of additional surgical risk (19%). For primary reconstruction, a high percentage of women also were highly concerned that reconstruction could mask cancer recurrence (62%). Although the majority of womenâunaffected with breast cancerâare interested in breast reconstruction, more than half of them cannot decide spontaneously about the timing and mode of surgery, including the medical women. The collected data emphasize the urgent necessity to systematically inform women and the whole population about the options of breast reconstruction. Equally important is for the involved surgeons to know the individual wishes and fears of women unexpectedly confronted with the diagnosis of breast cancer in order to provide comprehensive preoperative counselling with respect to cancer therapy including breast reconstructio
Molecular structure of highly-excited resonant states in Mg and the corresponding Be+O and C+C decays
Exotic Be and C decays from high-lying resonances in Mg are
analyzed in terms of a cluster model. The calculated quantities agree well with
the corresponding experimental data. It is found that the calculated decay
widths are very sensitive to the angular momentum carried by the outgoing
cluster. It is shown that this property makes cluster decay a powerful tool to
determine the spin as well as the molecular structures of the resonances.Comment: 17 pages, no figur
Bouncing wave packets, Ehrenfest theorem, and uncertainty relation based upon a new concept for the momentum of a particle in a box
For a particle in a box, the operator
is not self-adjoint and thus does not qualify as the physical momentum. As a result, in general the Ehrenfest theorem is violated. Based upon a recently developed new concept for a self-adjoint momentum operator, we reconsider the theorem and find that it is now indeed satisfied for all physically admissible boundary conditions. We illustrate these results for bouncing wave packets which first spread, then shrink, and return to their original form after a certain revival time. We derive a very simple form of the general HeisenbergâRobertsonâSchrödinger uncertainty relation and show that our construction also provides a physical interpretation for it
Averaging techniques for steady and unsteady calculations of a transonic fan stage
It is often desirable to characterize a turbomachinery flow field with a few lumped parameters such as total pressure ratio or stage efficiency. Various averaging schemes may be used to compute these parameters. The momentum, energy, and area averaging schemes are described and compared. The schemes were compared for two computed solutions of the midspan section of a transonic fan stage: a steady averaging-plane solution in which average rotor outflow conditions were used as stator inflow conditions, and an unsteady rotor-stator interaction solution. The solutions were computed on identical grids using similar Navier-Stokes codes and an algebraic turbulence model. The unsteady solution is described, some unsteady flow phenomena are discussed, and the steady pressure distributions are compared. Despite large unsteady pressure fluctuations on the stator surface, the steady pressure distribution matched the average unsteady distribution almost exactly. Stator wake profiles, stator loss coefficient, and stage efficiency were computed for the two solutions with the three averaging schemes and are compared. In general, the energy averaging scheme gave good agreement between the averaging-plane solution and the time-averaged unsteady solution, even though certain phenomena due to unsteady wake migration were neglected
Spontaneous Cdc42 polarization independent of GDI-mediated extraction and actin-based trafficking.
The small Rho-family GTPase Cdc42 is critical for cell polarization and polarizes spontaneously in absence of upstream spatial cues. Spontaneous polarization is thought to require dynamic Cdc42 recycling through Guanine nucleotide Dissociation Inhibitor (GDI)-mediated membrane extraction and vesicle trafficking. Here, we describe a functional fluorescent Cdc42 allele in fission yeast, which demonstrates Cdc42 dynamics and polarization independent of these pathways. Furthermore, an engineered Cdc42 allele targeted to the membrane independently of these recycling pathways by an amphipathic helix is viable and polarizes spontaneously to multiple sites in fission and budding yeasts. We show that Cdc42 is highly mobile at the membrane and accumulates at sites of activity, where it displays slower mobility. By contrast, a near-immobile transmembrane domain-containing Cdc42 allele supports viability and polarized activity, but does not accumulate at sites of activity. We propose that Cdc42 activation, enhanced by positive feedback, leads to its local accumulation by capture of fast-diffusing inactive molecules
Glasslike Arrest in Spinodal Decomposition as a Route to Colloidal Gelation
Colloid-polymer mixtures can undergo spinodal decomposition into colloid-rich
and colloid-poor regions. Gelation results when interconnected colloid-rich
regions solidify. We show that this occurs when these regions undergo a glass
transition, leading to dynamic arrest of the spinodal decomposition. The
characteristic length scale of the gel decreases with increasing quench depth,
and the nonergodicity parameter exhibits a pronounced dependence on scattering
vector. Mode coupling theory gives a good description of the dynamics, provided
we use the full static structure as input.Comment: 14 pages, 4 figures; replaced with published versio
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