1,905 research outputs found

    The effects of radiant heat on various regions of the human body

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    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

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    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 N=ZN=Z nuclei in terms of isovector pairing

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    A systematic investigation of the rotating N=ZN=Z even-even nuclei in the mass A=58−80A=58-80 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 npnp-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 t=0t=0 npnp-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

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    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 reconstruction—immediate or delayed—and in the case of rejection of treatment to find out the reasons for this reluctance. In a prospective study a sample of 200 women—divided into two groups—were 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 procedure—autologous versus non-autologous tissue—about 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 women—unaffected with breast cancer—are 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 24^{24}Mg and the corresponding 8^8Be+16^{16}O and 12^{12}C+12^{12}C decays

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    Exotic 8^8Be and 12^{12}C decays from high-lying resonances in 24^{24}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

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    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 Heisenberg–Robertson–Schrödinger uncertainty relation and show that our construction also provides a physical interpretation for it

    Spontaneous Cdc42 polarization independent of GDI-mediated extraction and actin-based trafficking.

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    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

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    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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