307 research outputs found

    Narrative Quilts and Quilted Narratives: The Art of Faith Ringgold and Alice Walker

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    There have been two main streams of influence on Chicano artists aside from the obvious one that is the result of their artistic training, education and development in the United States. The primary influence came from Mexico, first during the colonial period in the form of New Spanish art and architecture, and then in modem times provided by the Mexican muralists through their work and their use of pre-Columbian art. The New Spanish materials formed the nucleus for the second stream of influence composed of the various manifestations of religious folk art found primarily in the Southwest

    When good news leads to bad choices

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    Pigeons and other animals sometimes deviate from optimal choice behavior when given informative signals for delayed outcomes. For example, when pigeons are given a choice between an alternative that always leads to food after a delay and an alternative that leads to food only half of the time after a delay, preference changes dramatically depending on whether the stimuli during the delays are correlated with (signal) the outcomes or not. With signaled outcomes, pigeons show a much greater preference for the suboptimal alternative than with unsignaled outcomes. Key variables and research findings related to this phenomenon are reviewed, including the effects of durations of the choice and delay periods, probability of reinforcement, and gaps in the signal. We interpret the available evidence as reflecting a preference induced by signals for good news in a context of uncertainty. Other explanations are briefly summarized and compared

    Micromechanisms of paperboard deformation

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    Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2000.Includes bibliographical references (p. 245-246).An experimental study of the micromechanisms of paperboard deformation has been conducted. Experiments were performed in a scanning electron microscope, allowing visual observation and coincident acquisition of load vs. deformation data. Deformation mechanisms were determined and correlated with features of the load vs. deformation curves for different loading modes. A macroscopic study was performed concurrently to provide accurate continuum-level load vs. deformation data. This study contributed to an effort to model the creasing process. In creasing, paperboard is punched to create an internal line of damage and then folded along that line to create a corner. It has been determined experimentally that the creasing process involves through-thickness compression and transverse shear loading, as well as in-plane tension loading. Out-of-plane delamination also plays an important role. Experiments were conducted to determine the stress-strain behavior and corresponding deformation mechanisms under several well-controlled loading conditions. These include through-thickness compression, shear, and tension, as well as combined tension/shear loading. In-plane tensile behavior was also investigated. Paperboard loaded in out-of-plane compression behaved linearly at small strains, with an exponential increase in stiffness at larger strains. Deformation mechanisms included void closure and fiber collapse. In out-of-plane shear, paperboard initially behaved linearly, but departed from linearity before a peak in load. The dominant failure mechanism at the microscopic scale was sudden fiber disengagement throughout the entire cross-section, corresponding to the peak in load. Loaded in out-of-plane tension, the paperboard first exhibited many small cracks at the interfaces between layers. As these cracks grew, one became dominant, and all further delamination occurred by extension of that crack. Similar behavior was observed in combined loading experiments with tension as the larger load component. With shear as the larger component, delamination generally occurred suddenly rather than being preceded by small local cracks. In-plane tensile behavior also included an initial linear region, followed by nonlinearity and a peak in load. The dominant mechanisms were fiber break and fiber disengagement in the different layers of the board; this again corresponded to the ... [missing rest of abstract]by Heather M. Dunn.S.M

    The effect of gaze angle on visual acuity in infantile nystagmus

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    Purpose: Most individuals with infantile nystagmus (IN) have an idiosyncratic gaze angle at which their nystagmus intensity is minimized. Some adopt an abnormal head posture to use this β€œnull zone,” and it has therefore long been assumed that this provides people with nystagmus with improved visual acuity (VA). However, recent studies suggest that improving the nystagmus waveform could have little, if any, influence on VA; that is, VA is fundamentally limited in IN. Here, we examined the impact of the null zone on VA. Methods: Visual acuity was measured in eight adults with IN using a psychophysical staircase procedure with reversals at three horizontal gaze angles, including the null zone. Results: As expected, changes in gaze angle affected nystagmus amplitude, frequency, foveation duration, and variability of intercycle foveation position. Across participants, each parameter (except frequency) was significantly correlated with VA. Within any given individual, there was a small but significant improvement in VA (0.08 logMAR) at the null zone as compared with the other gaze angles tested. Despite this, no change in any of the nystagmus waveform parameters was significantly associated with changes in VA within individuals. Conclusions: A strong relationship between VA and nystagmus characteristics exists between individuals with IN. Although significant, the improvement in VA observed within individuals at the null zone is much smaller than might be expected from the occasionally large variations in intensity and foveation dynamics (and anecdotal patient reports of improved vision), suggesting that improvement of other aspects of visual performance may also encourage use of the null zone

    Nurses Alumni Association Bulletin, Fall 1986

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    Alumni Calendar Officers and Committee Chairmen The President\u27s Message Treasurer\u27s Report Nurses\u27 Relief Fund Scholarship Fund Surgery for the Unborn- A Nurse\u27s Own Story Further Remembrances Martha From the Tju Historian Old Main Congratulations to Our Graduates Advanced Placement Program and Masters in Rehabilitation Jefferson Surgical Center Opens Profile in Courage- Update Fiftieth Anniversary Happy Birthday Resume of Minutes of Alumni Association Meetings Alumni Office News Committee Reports Bulletin Social Scholarship Finance In Memoriam, Names of Deceased Graduates Luncheon Pictures Class Notes Caps, Pins, Transcripts, Class Address Lists Change of Address Form 1986CAHS Alumni Directory Bequests Relief Fund Application Scholarship Fund Application Membership Application Notice, Alumni Luncheo

    Sustained Activation of Lyn Tyrosine Kinase In Vivo Leads to Autoimmunity

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    Genetic ablation of the Lyn tyrosine kinase has revealed unique inhibitory roles in B lymphocyte signaling. We now report the consequences of sustained activation of Lyn in vivo using a targeted gain-of-function mutation (Lynup/up mice). Lynup/up mice have reduced numbers of conventional B lymphocytes, down-regulated surface immunoglobulin M and costimulatory molecules, and elevated numbers of B1a B cells. Lynup/up B cells are characterized by the constitutive phosphorylation of negative regulators of B cell antigen receptor (BCR) signaling including CD22, SHP-1, and SHIP-1, and display attributes of lymphocytes rendered tolerant by constitutive engagement of the antigen receptor. However, exaggerated positive signaling is also apparent as evidenced by the constitutive phosphorylation of Syk and phospholipase CΞ³2 in resting Lynup/up B cells. Similarly, Lynup/up B cells show a heightened calcium flux in response to BCR stimulation. Surprisingly, Lynup/up mice develop circulating autoreactive antibodies and lethal autoimmune glomerulonephritis, suggesting that enhanced positive signaling eventually overrides constitutive negative signaling. These studies highlight the difficulty in maintaining tolerance in the face of chronic stimulation and emphasize the pivotal role of Lyn in B cell signaling

    Primary Ciliary Dyskinesia: First Health-related Quality of Life Measures for Pediatric Patients

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    Rationale: Primary ciliary dyskinesia (PCD) is a rare disease. There are no available data on disease-specific pediatric patient–reported outcomes

    Constitutive Activation of the Src Family Kinase Hck Results in Spontaneous Pulmonary Inflammation and an Enhanced Innate Immune Response

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    To identify the physiological role of Hck, a functionally redundant member of the Src family of tyrosine kinases expressed in myelomonocytic cells, we generated HckF/F β€œknock-in” mice which carry a targeted tyrosine (Y) to phenylalanine (F) substitution of the COOH-terminal, negative regulatory Y499-residue in the Hck protein. Unlike their Hckβˆ’/βˆ’ β€œloss-of-function” counterparts, HckF/F β€œgain-of-function” mice spontaneously acquired a lung pathology characterized by extensive eosinophilic and mononuclear cell infiltration within the lung parenchyma, alveolar airspaces, and around blood vessels, as well as marked epithelial mucus metaplasia in conducting airways. Lungs from HckF/F mice showed areas of mild emphysema and pulmonary fibrosis, which together with inflammation resulted in altered lung function and respiratory distress in aging mice. When challenged transnasally with lipopolysaccharide (LPS), HckF/F mice displayed an exaggerated pulmonary innate immune response, characterized by excessive release of matrix metalloproteinases and tumor necrosis factor (TNF)Ξ±. Similarly, HckF/F mice were highly sensitive to endotoxemia after systemic administration of LPS, and macrophages and neutrophils derived from HckF/F mice exhibited enhanced effector functions in vitro (e.g., nitric oxide and TNFΞ± production, chemotaxis, and degranulation). Based on the demonstrated functional association of Hck with leukocyte integrins, we propose that constitutive activation of Hck may mimic adhesion-dependent priming of leukocytes. Thus, our observations collectively suggest an enhanced innate immune response in HckF/F mice thereby skewing innate immunity from a reversible physiological host defense response to one causing irreversible tissue damage
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