A Positive-Pressure Environment Disposable Shield (PEDS) for COVID-19 Health Care Worker Protection.

The COVID-19 pandemic has strained health care system resources and reduced the availability of life-sustaining and medical-grade personal protective equipment (PPE) though the combination of increased demand and disrupted manufacturing supply chains. As a result of these shortages, many health care providers have temporarily used largely untested, improvised PPE (iPPE). Lack of quality control for makeshift PPE and frequent repurposing of used items to conserve supplies increase both the risk of provider infection and nosocomial spread to uninfected patients. One strategy to reduce risk of infection and preserve existing equipment is the implementation of secondary barrier devices placed directly over patients or providers. The authors describe an inexpensive, disposable, positive-pressure head isolation unit that can be rapidly constructed from materials readily available in nearly all health care settings for under five US dollars. The unit was successfully deployed in Taiwan during the 2003 Severe Acute Respiratory Syndrome (SARS) outbreak, and again during the COVID-19 pandemic. The iPPE worn directly by the health care workers (HCWs) can be donned prior to patient contact in the presence of an air source. This strategy may be more protective than a covering placed over the patient in an aerosol-generating environment, which requires the HCW to be in close contact with the patient prior to securing the protective device

Zero-Bias Anomalies in Narrow Tunnel Junctions in the Quantum Hall Regime

We report on the study of cleaved-edge-overgrown line junctions with a serendipitously created narrow opening in an otherwise thin, precise line barrier. Two sets of zero-bias anomalies are observed with an enhanced conductance for filling factors $\nu > 1$ and a strongly suppressed conductance for $\nu < 1$. A transition between the two behaviors is found near $\nu \approx 1$. The zero-bias anomaly (ZBA) line shapes find explanation in Luttinger liquid models of tunneling between quantum Hall edge states. The ZBA for $\nu < 1$ occurs from strong backscattering induced by suppression of quasiparticle tunneling between the edge channels for the $n = 0$ Landau levels. The ZBA for $\nu > 1$ arises from weak tunneling of quasiparticles between the $n = 1$ edge channels.Comment: version with edits for clarit

Assessing the Formation Scenarios for the Double Nucleus of M31 Using Two-Dimensional Image Decomposition

The double nucleus geometry of M31 is currently best explained by the eccentric disk hypothesis of Tremaine, but whether the eccentric disk resulted from the tidal disruption of an inbounding star cluster by a nuclear black hole, or by an m=1 perturbation of a native nuclear disk, remains debatable. I perform detailed 2-D decomposition of the M31 double nucleus in the Hubble Space Telescope V-band to study the bulge structure and to address competing formation scenarios of the eccentric disk. I deblend the double nucleus (P1 and P2) and the bulge simultaneously using five Sersic and one Nuker components. P1 and P2 appear to be embedded inside an intermediate component (r_e=3.2") that is nearly spherical (q=0.97+/-m0.02), while the main galaxy bulge is more elliptical (q=0.81+/-0.01). The spherical bulge mass of 2.8x10^7 M_sol is comparable to the supermassive black hole mass (3x10^7 M_sol). In the 2-D decomposition, the bulge is consistent with being centered near the UV peak of P2, but the exact position is difficult to pinpoint because of dust in the bulge. P1 and P2 are comparable in mass. Within a radius r=1\arcsec of P2, the relative mass fraction of the nuclear components is M_BH:M_bulge:P1: P2 = 4.3:1.2:1:0.7, assuming the luminous components have a common mass-to-light ratio of 5.7. The eccentric disk as a whole (P1+P2) is massive, M ~ 2.1x10^7 M_sol, comparable to the black hole and the local bulge mass. As such, the eccentric disk could not have been formed entirely out of stars that were stripped from an inbounding star cluster. Hence, the more favored scenario is that of a disk formed in situ by an m=1 perturbation, caused possibly by the passing of a giant molecular cloud, or the passing/accretion of a small globular cluster.Comment: 19 pages, 8 figures. AJ accepted. For the version of this paper with high resolution figures, go to: http://zwicky.as.arizona.edu/~cyp/work/m31.ps.g

Feynman Rules in the Type III Natural Flavour-Conserving Two-Higgs Doublet Model

We consider a two Higgs-doublet model with $S_3$ symmetry, which implies a $\pi \over 2$ rather than 0 relative phase between the vacuum expectation values $$and$$. The corresponding Feynman rules are derived accordingly and the transformation of the Higgs fields from the weak to the mass eigenstates includes not only an angle rotation but also a phase transformation. In this model, both doublets couple to the same type of fermions and the flavour-changing neutral currents are naturally suppressed. We also demonstrate that the Type III natural flavour-conserving model is valid at tree-level even when an explicit $S_3$ symmetry breaking perturbation is introduced to get a reasonable CKM matrix. In the special case $\beta = \alpha$, as the ratio $\tan\beta = {v_2 \over v_1}$ runs from 0 to $\infty$, the dominant Yukawa coupling will change from the first two generations to the third generation. In the Feynman rules, we also find that the charged Higgs currents are explicitly left-right asymmetric. The ratios between the left- and right-handed currents for the quarks in the same generations are estimated.Comment: 16 pages (figures not included), NCKU-HEP/93-1

Alaska: Glaciers of Kenai Fjords National Park and Katmai National Park and Preserve

There are hundreds of glaciers in Kenai Fjords National Park (KEFJ) and Katmai National Park and Preserve (KATM) covering over 2,276 sq km of park land (ca. 2000). There are two primary glacierized areas in KEFJ (the Harding Icefield and the Grewingk-Yalik Glacier Complex) and three primary glacierized areas in KATM (the Mt. Douglas area, the Kukak Volcano to Mt. Katmai area, and the Mt. Martin area). Most glaciers in these parks terminate on land, though a few terminate in lakes. Only KEFJ has tidewater glaciers, which terminate in the ocean. Glacier mapping and analysis of the change in glacier extent has been accomplished on a decadal scale using satellite imagery, primarily Landsat data from the 1970s, 1980s, and from2000. Landsat Multispectral Scanner (MSS),Thematic Mapper (TM), and Enhanced Thematic Mapper Plus (ETM) imagery was used to map glacier extent on a park-wide basis. Classification of glacier ice using image-processing software, along with extensive manual editing, was employed to create Geographic Information System (GIS)outlines of the glacier extent for each park. Many glaciers that originate in KEFJ but terminate outside the park boundaries were also mapped. Results of the analysis show that there has been a reduction in the amount of glacier ice cover in the two parks over the study period. Our measurements show a reduction of approximately 21 sq km, or 1.5(from 1986 to 2000), and 76 sq km, or 7.7 (from19861987 to 2000), in KEFJ and KATM, respectively. This work represents the first comprehensive study of glaciers of KATM. Issues that complicate the mapping of glacier extent include debris cover(moraine and volcanic ash), shadows, clouds, fresh snow, lingering snow from the previous season, and differences in spatial resolution between the MSS,TM, or ETM sensors. Similar glacier mapping efforts in western Canada estimate mapping errors of 34. Measurements were also collected from a suite of glaciers in KEFJ and KATM detailing terminus positions and rates of recession using datasets including 15 min USGS quadrangle maps(19501951), Landsat imagery (19861987, 2000,2006), and 2005 IKONOS imagery (KEFJ only)

Alaska: Glaciers of Kenai Fjords National Park and Katmai and Lake Clark National Parks and Preserve

There are hundreds of glaciers in Kenai Fjords National Park (KEFJ) and Katmai National Park and Preserve (KATM) covering over 2276 sq km of park land (circa 2000). There are two primary glacierized areas in KEFJ -- the Harding Icefield and the Grewingk-Yalik Glacier Complex, and three primary glacierized areas in KATM - the Mt. Douglas area, the Kukak Volcano to Mt. Katmai area and the Mt. Martin area. Most glaciers in these parks terminate on land, though a few terminate in lakes. Only KEFJ has tidewater glaciers, which terminate in the ocean. Glacier mapping and analysis of the change in glacier extent has been accomplished on a decadal scale using satellite imagery, primarily Landsat data from the 1970s, 1980s, and from 2000. Landsat Multispectral Scanner (MSS), Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) imagery was used to map glacier extent on a park-wide basis. Classification of glacier ice using image processing software, along with extensive manual editing, was employed to create Geographic Information System (GIS) outlines of the glacier extent for each park. Many glaciers that originate in KEFJ but terminate outside the park boundaries were also mapped. Results of the analysis show that there has been a reduction in the amount of glacier ice cover in the two parks over the study period. Our measurements show a reduction of approximately 21 sq km, or -1.5% (from 1986 to 2000), and 76 sq km, or -7.7% (from 1986/87 to 2000), in KEFJ and KATM, respectively. This work represents the first comprehensive study of glaciers of KATM. Issues that complicate the mapping of glacier extent include: debris-cover (moraine and volcanic ash), shadows, clouds, fresh snow, lingering snow from the previous season, and differences in spatial resolution between the MSS and TM or ETM+ sensors. Similar glacier mapping efforts in western Canada estimate mapping errors of 3-4%. Measurements were also collected from a suite of glaciers in KEFJ and KATM detailing terminus positions and rates of recession using datasets including the 15-minute USGS quadrangle maps (1950/1951), Landsat imagery (1986/1987, 2000, 2006) and 2005 Ikonos imagery (KEFJ only)

T Oligo-Primed Polymerase Chain Reaction (TOP-PCR): A Robust Method for the Amplification of Minute DNA Fragments in Body Fluids.

Body fluid DNA sequencing is a powerful noninvasive approach for the diagnosis of genetic defects, infectious agents and diseases. The success relies on the quantity and quality of the DNA samples. However, numerous clinical samples are either at low quantity or of poor quality due to various reasons. To overcome these problems, we have developed T oligo-primed polymerase chain reaction (TOP-PCR) for full-length nonselective amplification of minute quantity of DNA fragments. TOP-PCR adopts homogeneous "half adaptor" (HA), generated by annealing P oligo (carrying a phosphate group at the 5' end) and T oligo (carrying a T-tail at the 3' end), for efficient ligation to target DNA and subsequent PCR amplification primed by the T oligo alone. Using DNA samples from body fluids, we demonstrate that TOP-PCR recovers minute DNA fragments and maintains the DNA size profile, while enhancing the major molecular populations. Our results also showed that TOP-PCR is a superior method for detecting apoptosis and outperforms the method adopted by Illumina for DNA amplification

Scaling of the anomalous Hall effect in Sr1−x_{1-x}Cax_xRuO3_3

The anomalous Hall effect (AHE) of ferromagnetic thin films of Sr$_{1-x}$Ca$_{x}$RuO$_3$ (0 $\leq x \leq$ 0.4) is studied as a function of $x$ and temperature $T$. As $x$ increases, both the transition temperature $T_c$ and the magnetization $M$ are reduced and vanish near $x \sim$ 0.7. For all compositions, the transverse resistivity $\rho_{H}$ varies non-monotonously with $T$, and even changes sign, thus violating the conventional expression $\rho_{H}=R_o B + 4\pi R_s M(T)$ ($B$ is the magnetic induction, while $R_o$ and $R_s$ are the ordinary and anomalous Hall coefficients). From the rather complicated data of $\rho_H$, we find a scaling behavior of the transverse conductivity $\sigma_{xy}$ with $M(T)$, which is well reproduced by the first-principles band calculation assuming the intrinsic origin of the AHE.Comment: REVTeX 4 style; 5 pages, 3 figures; revised 23/2 and accepted for publicatio