Recycling of epidermal growth factor-receptor complexes in A431 cells: identification of dual pathways

The intracellular sorting of EGF-receptor complexes (EGF-RC) has been studied in human epidermoid carcinoma A431 cells. Recycling of EGF was found to occur rapidly after internalization at 37 degrees C. The initial rate of EGF recycling was reduced at 18 degrees C. A significant pool of internalized EGF was incapable of recycling at 18 degrees C but began to recycle when cells were warmed to 37 degrees C. The relative rate of EGF outflow at 37 degrees C from cells exposed to an 18 degrees C temperature block was slower (t1/2 approximately 20 min) than the rate from cells not exposed to a temperature block (t1/2 approximately 5-7 min). These data suggest that there might be both short- and long-time cycles of EGF recycling in A431 cells. Examination of the intracellular EGF-RC dissociation and dynamics of short- and long-time recycling indicated that EGF recycled as EGF-RC. Moreover, EGF receptors that were covalently labeled with a photoactivatable derivative of 125I-EGF recycled via the long-time pathway at a rate similar to that of 125I-EGF. Since EGF-RC degradation was also blocked at 18 degrees C, we propose that sorting to the lysosomal and long-time recycling pathway may occur after a highly temperature-sensitive step, presumably in the late endosomes

X-ray film chamber with carbon target of Tien-Shan complex array

X-ray films were exposed inside the ionization calorimeter under 74g/sq cm of carbon and 5 cm of lead. The X-ray film chamber area is 35 sq. m. Moving X-ray films were used, 50% of the events, which succeeded to determine incidence time, were identified with corresponding extensive air showers (EAS). For such events the size spectrum of associated EAS was derived. Two methods of energy measurement using X-ray films and ionization calorimeter were compared. The energy transfer from selected hadron to electromagnetic component is illustrated. It is found that in cascades with high energy release into electromagnetic components the hadron component is practically absent

Generation of 10^15 - 10^17 eV photons by UHE CR in the Galactic magnetic filed

We show that the deep expected in the diffuse photon spectrum above the threshold of e+e- pair production, i.e., at energies 10^15 - 10^17 eV, may be absent due to the synchrotron radiation by the electron component of the extragalactic Ultra-High Energy Cosmic Rays (UHE CR) in the Galactic magnetic filed. The mechanism we propose requires small (less than 2x10^-12 G) extragalactic magnetic fields and large fraction of photons in the UHE CR. For a typical photon flux expected in top-down scenarios of UHE CR, the predicted flux in the region of the deep is close to the existing experimental limit. The sensitivity of our mechanism to the extragalactic magnetic field may be used to improve existing bounds on the latter by two orders of magnitude.Comment: 11 pages, LaTeX, 1 .ps figure. Numerical error corrected; references adde

Search for excess showers from Crab Nebula

The arrival directions of muon poor showers registrated in the Tien Shan experiment during an effective running time about I,8.IO(4)h were analyzed. It is shown that there is a significant excess of these showers coming the direction of Crab Nebula

Pressure ulcer: an unreported complication of the Safeguard® hemostasis device. No need to crack under pressure

Diagnostic cardiac catheterizations are predominantly performed using the femoral artery access. Several devices have been developed to aid in the closure of femoral arteriotomy

Cosmic Rays and Large Extra Dimensions

We have proposed that the cosmic ray spectrum "knee", the steepening of the cosmic ray spectrum at energy E \gsim 10^{15.5} eV, is due to "new physics", namely new interactions at TeV cm energies which produce particles undetected by the experimental apparatus. In this letter we examine specifically the possibility that this interaction is low scale gravity. We consider that the graviton propagates, besides the usual four dimensions, into an additional $\delta$, compactified, large dimensions and we estimate the graviton production in $p p$ collisions in the high energy approximation where graviton emission is factorized. We find that the cross section for graviton production rises as fast as $(\sqrt{s}/M_f)^{2+\delta}$, where $M_f$ is the fundamental scale of gravity in $4+\delta$ dimensions, and that the distribution of radiating a fraction $y$ of the initial particle's energy into gravitational energy (which goes undetected) behaves as $\delta y^{\delta -1}$. The missing energy leads to an underestimate of the true energy and generates a break in the {\sl inferred} cosmic ray spectrum (the "kne"). By fitting the cosmic ray spectrum data we deduce that the favorite values for the parameters of the theory are $M_f \sim 8$ TeV and $\delta =4$.Comment: 8 pages, 1 figur

Alignment in Gamma-Hadron Families of Cosmic Rays

Alignment of main fluxes of energy in a target plane is found in families of cosmic ray particles detected in deep lead X-ray chambers. The fraction of events with alignment is unexpectedly large for families with high energy and large number of hadrons. This can be considered as evidence for the existence of coplanar scattering of secondary particles in interaction of particles with superhigh energy, $E_0 > 10^{16}$ eV. Data analysis suggests that production of most aligned groups occurs low above the chamber and is characterized by a coplanar scattering and quasiscaling spectrum of secondaries in the fragmentation region. The most elaborated hypothesis for explanation of alignment is related to the quark-gluon string rupture. However, the problem of theoretical interpretation of our results still remains open.Comment: 15 pages, 2 tables, 6 figures (not included), Stanford University preprint SU-ITP-94-2