On the dynamic response of pressure transmission lines in the research of helium-charged free piston Stirling engines

In free piston Stirling engine research the integrity of both amplitude and phase of the dynamic pressure measurements is critical to the characterization of cycle dynamics and thermodynamics. It is therefore necessary to appreciate all possible sources of signal distortion when designing pressure measurement systems for this type of research. The signal distortion inherent to pressure transmission lines is discussed. Based on results from classical analysis, guidelines are formulated to describe the dynamic response properties of a volume-terminated transmission tube for applications involving helium-charged free piston Stirling engines. The scope and limitations of the dynamic response analysis are considered

Molecular profiling of resident and infiltrating mononuclear phagocytes during rapid adult retinal degeneration using single-cell RNA sequencing.

Neuroinflammation commonly accompanies neurodegeneration, but the specific roles of resident and infiltrating immune cells during degeneration remains controversial. Much of the difficulty in assessing myeloid cell-specific functions during disease progression arises from the inability to clearly distinguish between activated microglia and bone marrow-derived monocytes and macrophages in various stages of differentiation and activation within the central nervous system. Using an inducible model of photoreceptor cell death, we investigated the prevalence of infiltrating monocytes and macrophage subpopulations after the initiation of degeneration in the mouse retina. In vivo retinal imaging revealed infiltration of CCR2+ leukocytes across retinal vessels and into the parenchyma within 48 hours of photoreceptor degeneration. Immunohistochemistry and flow cytometry confirmed and characterized these leukocytes as CD11b+CD45+ cells. Single-cell mRNA sequencing of the entire CD11b+CD45+ population revealed the presence of resting microglia, activated microglia, monocytes, and macrophages as well as 12 distinct subpopulations within these four major cell classes. Our results demonstrate a previously immeasurable degree of molecular heterogeneity in the innate immune response to cell-autonomous degeneration within the central nervous system and highlight the necessity of unbiased high-throughput and high-dimensional molecular techniques like scRNAseq to understand the complex and changing landscape of immune responders during disease progression

In vivo imaging reveals transient microglia recruitment and functional recovery of photoreceptor signaling after injury.

Microglia respond to damage and microenvironmental changes within the central nervous system by morphologically transforming and migrating to the lesion, but the real-time behavior of populations of these resident immune cells and the neurons they support have seldom been observed simultaneously. Here, we have used in vivo high-resolution optical coherence tomography (OCT) and scanning laser ophthalmoscopy with and without adaptive optics to quantify the 3D distribution and dynamics of microglia in the living retina before and after local damage to photoreceptors. Following photoreceptor injury, microglia migrated both laterally and vertically through the retina over many hours, forming a tight cluster within the area of visible damage that resolved over 2 wk. In vivo OCT optophysiological assessment revealed that the photoreceptors occupying the damaged region lost all light-driven signaling during the period of microglia recruitment. Remarkably, photoreceptors recovered function to near-baseline levels after the microglia had departed the injury locus. These results demonstrate the spatiotemporal dynamics of microglia engagement and restoration of neuronal function during tissue remodeling and highlight the need for mechanistic studies that consider the temporal and structural dynamics of neuron-microglia interactions in vivo

Farm-Level Impacts of Banning Growth- Promoting Antibiotic Use in U.S. Pig Grower/Finisher Operations

Antibiotics have been used by pig producers for several decades, and are now used routinely. This study documents the current productivity and economic impacts of the use of antibiotics for growth promotion (AGP) by pig grower/finishers at the farm level. We evaluate the impacts of an AGP ban, and use of AGP by all pig grower/finishers for 61S90 days (a more production-efficient level), using data from the National Animal Health Monitoring System Swine 2000 Survey. Findings indicate that pig productivity improves with AGP. Relative to current use, an AGP ban would decrease producer profits by $1,400 per 1,020-head barn, and profits would increase by$1,992 for each grower/finisher barn when AGP is fed for 61 to 90 days. There is increasing concern about the use of antibiotics in animal production, partly because of the selection for antibiotic resistance. Thus, a careful examination of the value of AGP in pork production is warranted.antibiotics, antimicrobial resistance, growth promotion, pigs, production, Agricultural and Food Policy, Health Economics and Policy, Livestock Production/Industries,

PRODUCER INCENTIVES FOR ANTIBIOTIC USE IN U.S. PORK PRODUCTION

Antibiotics have been used in animal production for several decades. Antibiotics are used routinely now in pork production (NAHMS 2002). There is increasing concern about the use of antibiotics in animal production. There is no hard evidence supporting the link of antibiotic use in animals to observations of antibiotic resistance infections in people. Nonetheless a careful examination of the value of continued antibiotic use in agricultural, and in pork production in particular is warranted. Therefore, the objective of our study is to validate the productivity and economic impacts of antibiotic use for pig producers at the farm level. We use data from the NAHMS 2000 swine survey. We estimate the combined affects from antibiotics used for growth promotion (AGP) and antibiotics used for disease prevention (ADP) on 4 productivity measures. We also estimate the economic impact of AGP and ADP for individual pig producers. We estimate these 4 productivity measures using seemingly unrelated regression analysis. We evaluate 4 scenarios which ban antibiotic use, and use a simple synthetic firm partial budget to estimate the economic consequences of these scenarios. We find that pig productivity is improved with AGP, but decreased with ADP. A total ban on AGP would cost pig producers $1,271 in lost profits per 1,020 head pig barn. A total ban on ADP however, would result in pig producers improving profits slightly. This occurs because productivity is negatively influenced by ADP. A ban of both AGP and ADP results in a small loss of producer profits ($376/1,020 head barn) because of the offsetting effects of ADP compared to AGP. Producers have higher profits when AGP and ADP are applied at levels where pig productivity is maximized. In this case, producers gain $4,146 for each 1,020 head barn compared to no antibiotic use.Livestock Production/Industries,

Hypervelocity Impact of Composite Overwrap Pressure Vessels

There is a limited amount of hypervelocity impact (HVI) data on pressurized composite overwrapped pressure vessels (COPV). In recent years, NASA has performed HVI tests to characterize impact conditions resulting in either leak or burst of the COPVs representative of spacecraft hardware. This paper reports on the results of 40 tests that have been conducted on several types of COPV configurations, pressurized by inert gas to near the vessels rated maximum expected operating pressure (MEOP). These tests were used to better understand COPV response under HVI conditions and develop ballistic limit equations (BLE) related to these tests

Observations on the Mating Behavior of Captive Spotted Sand Bass (Paralabrax maculatofasciatus)

The sex allocation pattern of various populations of spotted sand bass are thought to vary from functional gonochorism to strict protogyny. The development of hypotheses explaining how such a plastic (flexible) strategy has been maintained selectively has been hindered by a general lack of information on reproductive behavior in this species. Therefore, the spawning behavior of adult, wild-caught spotted sand bass were observed in captivity under a variety of densities. Three distinct spawning modes were observed: 1) pair spawning, 2) group spawning, and 3) spawning including a sneaker male. Courtship was characterized by the following sequence: 1) a male or males approach the females, 2) one or more males make contact with the ventro-lateral surface of the female and chase the female, 3) the male contacts the ventro-lateral surface of the female and pushes her through a vertical spawning rush. Spawning behavior involved ephemeral color changes, persistent physical contact initiated by the male, short rushes beginning near structure and ending in a vertical rush with a gamete release. In general, in low density groups, reproductive activity was dominated by a single male that actively excluded smaller males from spawning. The dominant male in these groups exclusively engaged in pair spawning. Individuals in groups of higher density spawned in groups, with no observations of large males monopolizing females. These observations are consistent with the predictions of the size-advantage hypothesis regarding mating strategies in fishes. We propose that these three spawning modes and the frequency with which they occur allow the flexibility seen in the mating strategies of isolated populations of spotted sand bass

Injustice perceptions about pain: parent–child discordance is associated with worse functional outcomes

Pain is experienced within and influenced by social environments. For children with chronic pain, the child–parent relationship and parental beliefs about pain are particularly important and may influence pain outcomes. Pain-related injustice perceptions have recently been identified as an important cognitive–emotional factor for children with pain. The current study aimed to better understand the pain-related injustice perceptions of children with chronic pain and their parents. The sample consisted of 253 pediatric chronic pain patients (mean age = 14.1 years, 74% female) presenting to a tertiary pain clinic. Patients completed measures of pain intensity, pain-related injustice perceptions, stress, functional disability, and quality of life. Parents completed a measure of pain-related injustice perceptions about their child's pain. Child–parent dyads were categorized into 1 of 4 categories based on the degree of concordance or discordance between their scores on the injustice measures. One-way analysis of variances examined differences in pain intensity, stress, functional disability, and quality of life across the 4 dyad categories. Our findings indicated that both the degree (concordant vs discordant) and direction (discordant low child–high parent vs discordant high child–low parent) of similarity between child and parent injustice perceptions were associated with child-reported pain intensity, stress, functional disability, and quality of life. The poorest outcomes were reported when children considered their pain as highly unjust, but their parents did not. These findings highlight the important role of parents in the context of pain-related injustice perceptions in pediatric chronic pain