Modular Rake of Pitot Probes

The figure presents selected views of a modular rake of 17 pitot probes for measuring both transient and steady-state pressures in a supersonic wind tunnel. In addition to pitot tubes visible in the figure, the probe modules contain (1) high-frequency dynamic-pressure transducers connected through wires to remote monitoring circuitry and (2) flow passages that lead to tubes that, in turn, lead to remote steady-state pressure transducers. Prior pitot-probe rakes were fabricated as unitary structures, into which the individual pitot probes were brazed. Repair or replacement of individual probes was difficult, costly, and time-consuming because (1) it was necessary to remove entire rakes in order to unbraze individual malfunctioning probes and (2) the heat of unbrazing a failed probe and of brazing a new probe in place could damage adjacent probes. In contrast, the modules in the present probe are designed to be relatively quickly and easily replaceable with no heating and, in many cases, without need for removal of the entire rake from the wind tunnel. To remove a malfunctioning probe, one first removes a screw-mounted V-cross-section cover that holds the probe and adjacent probes in place. Then one removes a screw-mounted cover plate to gain access to the steady-state pressure tubes and dynamicpressure wires. Next, one disconnects the tube and wires of the affected probe. Finally, one installs a new probe in the reverse of the aforementioned sequence. The wire connections can be made by soldering, but to facilitate removal and installation, they can be made via miniature plugs and sockets. The connections between the probe flow passages and the tubes leading to the remote pressure sensors can be made by use of any of a variety of readily available flexible tubes that can be easily pulled off and slid back on for removal and installation, respectively

Fidelity enhancement by logical qubit encoding

We demonstrate coherent control of two logical qubits encoded in a decoherence free subspace (DFS) of four dipolar-coupled protons in an NMR quantum information processor. A pseudo-pure fiducial state is created in the DFS, and a unitary logical qubit entangling operator evolves the system to a logical Bell state. The four-spin molecule is partially aligned by a liquid crystal solvent, which introduces strong dipolar couplings among the spins. Although the system Hamiltonian is never fully specified, we demonstrate high fidelity control over the logical degrees of freedom. In fact, the DFS encoding leads to higher fidelity control than is available in the full four-spin Hilbert space.Comment: 10 pages, 2 figure

“We Never Get Stuck:” A Collaborative Analysis of Change and Coastal Community Subsistence Practices in the Northern Bering and Chukchi Seas, Alaska

The Indigenous communities of the northern Bering Sea and Chukchi Sea are experiencing extensive social, economic, and technological change. The region’s marine ecosystem is also characterized by a high degree of variability and by rapid change. Residents of eight coastal communities from Savoonga to Utqiaġvik were involved in the Chukchi Coastal Communities Project, which used the results of a literature review together with the experiences of the community participants to co-analyze what is known about societal and environmental change in the region and what the communities’ experiences have been in responding to those changes. Some of the observed changes are transient in duration and effect, such as the passage of an individual ship, whereas others, such as the creation of the Red Dog Mine Port Site, persist and may force coastal residents to make lasting changes in their activities. Some responses can use existing knowledge (e.g., hunting bowhead whales in fall as well as spring), whereas others may require learning and experimentation (e.g., harvesting new species such as the Hanasaki crab). Our findings show that the results of a change are more important than the source of the change. They also emphasize the continuing importance of traditional values and practices as well as attitudes conducive to persistence and innovation. Indigenous leadership is an essential component of continued resilience as the ecosystem continues to change. The resilient characteristics of coastal communities and their ability to determine their own responses to change need greater attention to match the research effort directed at understanding the ecosystem. Les collectivités autochtones du nord de la mer de Béring et de la mer des Tchouktches font face à d’importants changements sur les plans social, économique et technologique. L’écosystème marin de la région est également caractérisé par un grand degré de variabilité et de changement rapide. Les habitants de huit collectivités côtières, de Savoonga à Utqiaġvik, ont participé au projet des collectivités côtières des Tchouktches. S’appuyant sur l’examen de documentation et sur l’expérience des participants des collectivités, les responsables de ce projet ont co-analysé les faits connus au sujet du changement social et environnemental dans la région de même que l’expérience des collectivités en matière de réponse à ces changements. La durée et l’effet des changements observés sont parfois transitoires, comme le passage d’un navire, tandis que d’autres, comme l’aménagement du site portuaire de la mine de Red Dog, perdurent et risquent de forcer les habitants de la côte à modifier leurs activités en permanence. Certaines des réponses peuvent s’appuyer sur des connaissances déjà acquises (comme le fait de chasser la baleine boréale à l’automne ainsi qu’au printemps), tandis que d’autres pourraient nécessiter de l’apprentissage et de l’expérimentation (comme la récolte d’une nouvelle espèce comme le crabe Hanasaki). Nos constatations démontrent que les résultats d’un changement sont plus importants que la source du changement. Elles mettent également l’accent sur l’importance continuelle des valeurs et des pratiques traditionnelles ainsi que sur les attitudes propices à la persistance et à l’innovation. Le leadership autochtone est une composante essentielle de la résilience continue alors que l’écosystème évolue sans cesse. Les caractéristiques de résilience des collectivités côtières et leur capacité à déterminer leurs propres réponses au changement doivent faire l’objet d’une plus grande attention afin d’être à la hauteur de l’effort de recherche visant à comprendre l’écosystème.&nbsp

Alignment Cube with One Diffractive Face

An enhanced alignment cube has been invented for use in a confined setting (e.g., a cryogenic chamber) in which optical access may be limited to a single line of sight. Whereas traditional alignment-cube practice entails the use of two theodolites aimed along two lines of sight, the enhanced alignment cube yields complete alignment information through use of a single theodolite aimed along a single line of sight. Typically, an alignment cube is placed in contact with a datum surface or other reference feature on a scientific instrument during assembly or testing of the instrument. The alignment cube is then used in measuring a small angular deviation of the feature from a precise required orientation. Commonly, the deviation is expressed in terms of rotations (Rx,Ry,Rz) of the cube about the corresponding Cartesian axes (x,y,z). In traditional practice, in order to measure all three rotations, it is necessary to use two theodolites aimed at two orthogonal faces of the alignment cube, as shown in the upper part of the figure. To be able to perform such a measurement, one needs optical access to these two faces. In the case of an alignment cube inside a cryogenic chamber or other enclosed space, the optical-access requirement translates to a requirement for two windows located along the corresponding two orthogonal lines of sight into the chamber. In a typical application, it is difficult or impossible to provide two windows. The present enhanced version of the alignment cube makes it possible to measure all three rotations by use of a single line of sight, thereby obviating a second window

Ursinus College Alumni Journal, Spring 1969

Mark your calendar • Mailer: Anatomizer of the moral malaise • From the President • The dimensions of history • Centennial celebration report • Ursinus names new alumni director • Revised Alumni Association constitution • The end of an era • Financial development report: steady progress • A bride for the first time • Candidates for office • Girls\u27 field hockey review • Ursinus Women\u27s Club: A record of achievement • Campus clippings: 100 years ago; News media report; Coach and athlete • Class notes • In memoriam • Weddings • Birthshttps://digitalcommons.ursinus.edu/alumnijournal/1094/thumbnail.jp

The Next Generation Virgo Cluster Survey - Infrared (NGVS-IR): I. A new Near-UV/Optical/Near-IR Globular Cluster selection tool

The NGVS-IR project (Next Generation Virgo Survey - Infrared) is a contiguous near-infrared imaging survey of the Virgo cluster of galaxies. It complements the optical wide-field survey of Virgo (NGVS). The current state of NGVS-IR consists of Ks-band imaging of 4 deg^2 centered on M87, and J and Ks-band imaging of 16 deg^2 covering the region between M49 and M87. In this paper, we present the observations of the central 4 deg^2 centered on Virgo's core region. The data were acquired with WIRCam on the Canada-France-Hawaii Telescope and the total integration time was 41 hours distributed in 34 contiguous tiles. A survey-specific strategy was designed to account for extended galaxies while still measuring accurate sky brightness within the survey area. The average 5\sigma limiting magnitude is Ks=24.4 AB mag and the 50% completeness limit is Ks=23.75 AB mag for point source detections, when using only images with better than 0.7" seeing (median seeing 0.54"). Star clusters are marginally resolved in these image stacks, and Virgo galaxies with \mu_Ks=24.4 AB mag arcsec^-2 are detected. Combining the Ks data with optical and ultraviolet data, we build the uiK color-color diagram which allows a very clean color-based selection of globular clusters in Virgo. This diagnostic plot will provide reliable globular cluster candidates for spectroscopic follow-up campaigns needed to continue the exploration of Virgo's photometric and kinematic sub-structures, and will help the design of future searches for globular clusters in extragalactic systems. Equipped with this powerful new tool, future NGVS-IR investigations based on the uiK diagram will address the mapping and analysis of extended structures and compact stellar systems in and around Virgo galaxies.Comment: 23 pages, 18 figures. Accepted for publication in ApJ

Ursinus College Alumni Journal, November 1968

Ursinus College calendar • Politics 1968: That was the year that was • From the President • All-Ursinus anniversary drive: A report from the National Chairman • Stained glass on campus • An end of Pax Americana • Freeland Hall: A birthplace revisited • Episodes in the life of Freeland Hall • Homecoming 1968 • Centennial: The liberal arts in higher learning • Sports scene: Miss Snell honored; Harriers keep winning; Mills keeps kicking • Ursinus honors four at Founders\u27 Day • Church appeal gains momentum • Class of \u2772: A pictorial essay • Campus clippings: Alumni award planned; Television stars; Beatle buff on campus; Subscribe to the Weekly • Class notes • Weddings • Births • In memoriamhttps://digitalcommons.ursinus.edu/alumnijournal/1093/thumbnail.jp

The Boundary Conditions of the Heliosphere: Photoionization Models Constrained by Interstellar and In Situ Data

The boundary conditions of the heliosphere are set by the ionization, density and composition of inflowing interstellar matter. Constraining the properties of the Local Interstellar Cloud (LIC) at the heliosphere requires radiative transfer ionization models. We model the background interstellar radiation field using observed stellar FUV and EUV emission and the diffuse soft X-ray background. We also model the emission from the boundary between the LIC and the hot Local Bubble (LB) plasma, assuming that the cloud is evaporating because of thermal conduction. We create a grid of models covering a plausible range of LIC and LB properties, and use the modeled radiation field as input to radiative transfer/thermal equilibrium calculations using the Cloudy code. Data from in situ observations of He^O, pickup ions and anomalous cosmic rays in the heliosphere, and absorption line measurements towards epsilon CMa were used to constrain the input parameters. A restricted range of assumed LIC HI column densities and LB plasma temperatures produce models that match all the observational constraints. The relative weakness of the constraints on N(HI) and T_h contrast with the narrow limits predicted for the H^O and electron density in the LIC at the Sun, n(H^0) = 0.19 - 0.20 cm^-3, and n(e) = 0.07 +/- 0.01 cm^-3. Derived abundances are mostly typical for low density gas, with sub-solar Mg, Si and Fe, possibly subsolar O and N, and S about solar; however C is supersolar. The interstellar gas at the Sun is warm, low density, and partially ionized, with n(H) = 0.23 - 0.27 cm^-3, T = 6300 K, X(H^+) ~ 0.2, and X(He^+) ~ 0.4. These results appear to be robust since acceptable models are found for substantially different input radiation fields. Our results favor low values for the reference solar abundances for the LIC composition.Comment: 14 pages, 4 figures, submitted to Astronomy & Astrophysics together with papers from the International Space Sciences Institute workshop on Interstellar Hydrogen in the Heliospher