Skin Necrosis Distal to a Rapid Infusion Catheter: Understanding Possible Complications of Large-bore Vascular Access Devices.

Rapid infusion catheters (RICs) allow expedient conversion of peripheral intravenous (PIV) catheters to peripheral sheaths; however, little is known about potential complications. In this case, a 64-year-old male polytrauma patient had a 20-gauge PIV catheter in the right cephalic vein upsized to an 8.5 French (Fr) RIC without incident during an arrest with pulseless electrical activity (PEA). On RIC post-placement day two, the patient developed edema and ecchymosis extending from the right dorsal mid-hand to the antecubital fossa, just distal to the RIC insertion point. Compartments were soft; the volar surface (including an arterial line location), fingers, and upper arm were normal. The RIC flushed and returned blood appropriately. Ultrasound revealed a noncompressible cephalic vein either related to the catheter or thrombosis, and imaging of the hand showed an ulnar styloid fracture and a minimally displaced triquetral fracture. The RIC was removed immediately. Over the next week, the areas of ecchymosis developed bullae and then sloughed, leaving open wounds extending into the dermis. The patient later expired from unrelated causes. The area and timing of the skin necrosis were highly suspicious for a catheter-associated complication, despite the presence of the arterial line and small distal fractures. The necrosis was potentially due to thrombosis of the superficial venous outflow system, leading to congestion and skin compromise, but we found no similar reports. Alternatively, the catheter may have ruptured the vein and caused a gravity-dependent ecchymosis, but the volar surface was not impacted, and the catheter was functioning properly. The RIC may also have encroached on the arterial space, decreasing flow, but we would have expected distal hand changes. The only published reports we could find on RIC complications involved a lost guide wire, fragmentation of a catheter during placement, and a case of compartment syndrome, raising the question of whether skin necrosis is truly a rare event or simply underreported with the RIC. Although the exact causal relationship remains unknown in our case, RICs should be removed as soon as possible after immediate stabilization

Ising metamagnets in thin film geometry: equilibrium properties

Artificial antiferromagnets and synthetic metamagnets have attracted much attention recently due to their potential for many different applications. Under some simplifying assumptions these systems can be modeled by thin Ising metamagnetic films. In this paper we study, using both the Wang/Landau scheme and importance sampling Monte Carlo simulations, the equilibrium properties of these films. On the one hand we discuss the microcanonical density of states and its prominent features. On the other we analyze canonically various global and layer quantities. We obtain the phase diagram of thin Ising metamagnets as a function of temperature and external magnetic field. Whereas the phase diagram of the bulk system only exhibits one phase transition between the antiferromagnetic and paramagnetic phases, the phase diagram of thin Ising metamagnets includes an additional intermediate phase where one of the surface layers has aligned itself with the direction of the applied magnetic field. This additional phase transition is discontinuous and ends in a critical end point. Consequently, it is possible to gradually go from the antiferromagnetic phase to the intermediate phase without passing through a phase transition.Comment: 8 figures, accepted for publication in Physical Review

Momentum Distribution for Bosons with Positive Scattering Length in a Trap

The coordinate-momentum double distribution function $\rho ({\bf r}, {\bf p}) d^{3}rd^{3}p$ is calculated in the local density approximation for bosons with positive scattering length $a$ in a trap. The calculation is valid to the first order of $a$. To clarify the meaning of the result, it is compared for a special case with the double distribution function $\rho_{w}d^{3} rd^{3}p$ of Wigner.Comment: Latex fil

A Tunable Anomalous Hall Effect in a Non-Ferromagnetic System

We measure the low-field Hall resistivity of a magnetically-doped two-dimensional electron gas as a function of temperature and electrically-gated carrier density. Comparing these results with the carrier density extracted from Shubnikov-de Haas oscillations reveals an excess Hall resistivity that increases with decreasing temperature. This excess Hall resistivity qualitatively tracks the paramagnetic polarization of the sample, in analogy to the ferromagnetic anomalous Hall effect. The data are consistent with skew-scattering of carriers by disorder near the crossover to localization

A Methodology for Characterization of the Strain Rate-Dependent Behavior of PU Foam

Polymeric foams are known to be sensitive to strain rate under dynamic loads. Mechanical characterization of such materials would not thus be complete without capturing the effect of strain rate on their stress-strain behaviors. Consistent data on the dynamic behavior of foam is also necessary for designing energy-absorbing countermeasures based on foam such as for vehicle occupant safety protection. Strain rates of the order of 100-500 s−1 are quite common in such design applications; strain rates of this range cannot be obtained with an ordinary UTM (universal testing machine) and a special test set-up is usually needed. In the current study, a unique approach has been suggested according to which quasi-static tests at low strain rates and low velocity drop tests at medium strain rates are utilized to arrive at an empirical relation between initial peak stress and logarithm of strain rate for a rigid closed-cell PU foam. Using a stress-scaling methodology and the empirical relation mentioned, foam stress-strain curves are obtained for a number of strain rates spanning low (from 0.00033 s−1) to high strain rates (up to1000 s−1). This data on foam material behavior is expected to be particularly useful in numerical modelling of foam-based countermeasures for impact energy absorption applications

Correlation of high energy muons with primary composition in extensive air shower

An experimental investigation of high energy muons above 200 GeV in extensive air showers has been made for studying high energy interaction and primary composition of cosmic rays of energies in the range 10 to the 14th power approx. 10 to the 15th power eV. The muon energies are estimated from the burst sizes initiated by the muons in the rock, which are measured by four layers of proportional counters, each of area 5 x 2.6 sq m, placed at 30 m.w.e. deep, Funasaka tunnel vertically below the air shower array. These results are compared with Monte Carlo simulations based on the scaling model and the fireball model for two primary compositions, all proton and mixed

Comment on "Raman spectroscopy study of NaxCoO2 and superconducting NaxCoO2 yH2O"

The effect of surface degradation of the thermolectric cobaltite on Raman spectra is discussed and compared to experimental results from Co3O4 single crystals. We conclude that on NaCl flux grown NaxCoO2 crystals a surface layer of Co3O4 easily forms that leads to the observation of an intense phonon around 700 cm-1 [Phys. Rev. B 70, 052502 (2004)]. Raman spectra on freshly cleaved crystals from optical floating zone ovens do not show such effects and have a high frequency phonon cut-off at approximately 600 cm -1 [Phys. Rev. Lett 96, 167204 (2006)]. We discuss the relation of structural dimensionality, electronic correlations and the high frequency phonon cut-off of the thermolectric cobaltite.Comment: 2 pages, 1 figure, to be published in Phys. Rev. B (2007

Shubnikov de Haas effect in the metallic state of Na0.3_{0.3}CoO2_2

Shubnikov de Haas oscillations for two well defined frequencies, corresponding respectively to areas of 0.8 and 1.36% of the first Brillouin zone (FBZ), were observed in single crystals of Na$_{0.3}$CoO$_2$. The existence of Na superstructures in Na$_{0.3}$CoO$_2$, coupled with this observation, suggests the possibility that the periods are due to the reconstruction of the large Fermi surface around the $\Gamma$ point. An alternative interpretation in terms of the long sought-after $\epsilon_g^\prime$ pockets is also considered but found to be incompatible with existing specific heat data.Comment: 5 pages 4 figure

Nonmagnetic impurity perturbation to the quasi-two-dimensional quantum helimagnet LiCu2O2

A complete phase diagram of Zn substituted quantum quasi-two-dimensional helimagnet LiCu2O2 has been presented. Helical ordering transition temperature (T_h) of the original LiCu2O2 follows finite size scaling for less than ~ 5.5% Zn substitution, which implies the existence of finite helimagnetic domains with domain boundaries formed with nearly isolated spins. Higher Zn substitution > 5.5% quenches the long-range helical ordering and introduces an intriguing Zn level dependent magnetic phase transition with slight thermal hysteresis and a universal quadratic field dependence for T_c (Zn > 0.055,H). The magnetic coupling constants of nearest-neighbor (nn) J1 and next-nearest-neighbor (nnn) J2 (alpha=J2/J1) are extracted from high temperature series expansion (HTSE) fitting and N=16 finite chain exact diagonalization simulation. We have also provided evidence of direct correlation between long-range helical spin ordering and the magnitude of electric polarization in this spin driven multiferroic material