An Integrated Interdisciplinary Sleep Care Model-The Ultimate Dream Team.

This Viewpoint discusses the need for diverse physicians to manage sleep health.

Amoebic gill disease increases energy requirements and decreases hypoxia tolerance in Atlantic salmon (Salmo salar) smolts.

Globally, Atlantic salmon (Salmo salar Linnaeus) aquaculture is now routinely affected by amoebic gill disease (AGD; Neoparamoeba perurans). The disease proliferates throughout the summer and is implicated in decreasing tolerance of salmon to environmental perturbations, yet little empirical evidence exists to support these observations. Using salmon acclimated to 15 or 19 °C, our aim was to determine the effects of clinically light-moderate (industry-relevant) AGD on metabolism (MO2rest and MO2max), aerobic scope (MO2max - MO2rest), excess post-exercise oxygen consumption (EPOC), and hypoxia tolerance. An increase in MO2rest (~8% and ~ 13% increase within the 15 and 19 °C acclimation groups, respectively) with increasing disease signs demonstrated an increase in baseline energy requirements as the disease progressed. Conversely, MO2max remained stable at both temperatures (~364 mg O2 kg-1 h-1), resulting in a decline in aerobic scope by 13 and 19% in the 15 and 19 °C groups, respectively. There was evidence of a decrease in hypoxia tolerance as the dissolved oxygen concentrations at loss of equilibrium increased by ~8% with more severe lesion coverage of the gills. These results suggest an increase in basal energy requirements and reduction in hypoxia tolerance as AGD proliferates, lending support to the idea that AGD reduces environmental tolerance. However, the lack of an effect of acclimation temperature indicates that the temperature-disease interaction may be more complicated than currently thought.

Aerobic and anaerobic movement energetics of hybrid and pure parental abalone.

The underlying mechanisms controlling growth heterosis in marine invertebrates remain poorly understood. We used pure blacklip (Haliotis rubra) and greenlip (Haliotis laevigata) abalone, as well as their hybrid, to test whether differences in movement and/or aerobic versus anaerobic energy use are linked to a purported increased growth rate in hybrids. Abalone were acclimated to control (16 °C) and typical summer temperatures (23 °C), each with oxygen treatments of 100% air saturation (O2sat) or 70% O2sat. The experiment then consisted of two phases. During the first phase (chronic exposure), movement and oxygen consumption rates (MO2) of abalone were measured during a 2 day observation period at stable acclimation conditions. Additionaly, lactate dehydrogenase (LDH) and tauropine dehydrogenase (TDH) activities were measured. During phase two (acute exposure), O2sat was raised to 100% for abalone acclimated to 70% O2sat followed by an acute decrease in oxygen to anoxia for all acclimation groups during which movement and MO2 were determined again. During the chronic exposure, hybrids and H. laevigata moved shorter distances than H. rubra. Resting MO2, LDH and TDH activities, however, were similar between abalone types but were increased at 23 °C compared to 16 °C. During the acute exposure, the initial increase to 100% O2sat for individuals acclimated to 70% O2sat resulted in increased movement compared to individuals acclimated to 100% O2sat for hybrids and H. rubra when compared within type of abalone. Similarly, MO2 during spontaneous activity of all three types of abalone previously subjected to 70% O2sat increased above those at 100% O2sat. When oxygen levels had dropped below the critical oxygen level (Pcrit), movement in hybrids and H. laevigata increased up to 6.5-fold compared to movement above Pcrit. Differences in movement and energy use between hybrids and pure species were not marked enough to support the hypothesis that the purportedly higher growth in hybrids is due to an energetic advantage over pure species.

Comparative Content Analysis of Self-Report Scales for Level of Personality Functioning.

Content validity analyses of eight self-report instruments for assessing severity of personality disorder (PD), also known as Level of Personality Functioning (LPF), were conducted using the conceptual scheme of the Alternative Model for Personality Disorders (AMPD; APA, 2013). The item contents of these eight inventories were characterized for the LPF constructs of Identity (ID), Self-Direction (SD), Empathy (EM), and Intimacy (IN) along with the pathological personality trait domains of Negative Affectivity, Detachment, Antagonism, Disinhibition, and Psychoticism. Severity of pathology (SV) reflected in item content was also rated. Raters demonstrated robust agreement for AMPD and SV constructs across instruments. Similarity between instrument AMPD construct profiles was quantified by intraclass correlations (ICC). Results showed the instruments were generally similar in AMPD-construct coverage, but some important differences emerged. The subscales of the instruments also were characterized for the degree to which they reflect the four LPF (ID, SD, EM, IN) domain constructs. Collectively, these content validity comparisons clarify the equivalence of instruments for AMPD constructs and the relative proportions of construct coverage within instrument subscales. These results can inform future research with LPF self-report instruments and guide clinicians in selecting an LPF-related instrument for use in practice.

Is Essentialism Essential? Reducing Homonegative Prejudice by Targeting Diverse Sexual Orientation Beliefs.

We conducted an experiment to assess whether targeting multiple beliefs about sexual orientation (SO) may be more effective in reducing homonegativity than focusing only on beliefs about its biogenetic origins. Participants (116 women, 85 men) were randomly assigned to one of three treatment conditions or a control condition. Those in the treatment conditions read essays summarizing: (1) research suggesting SO has biogenetic origins, (2) research suggesting SO is socially constructed and refuting beliefs about the discreteness, homogeneity, and informativeness of SO categories; or (3) research suggesting SO is biogenetic and research suggesting SO categories are socially constructed and not necessarily discrete, homogenous, or informative. We predicted participants in the conditions that targeted multiple beliefs related to the social construction of SO, not just its biogenetic origins, would exhibit the strongest reductions in beliefs about the discreteness, homogeneity, and informativeness of SO categories, and in homonegativity. We also predicted these participants would exhibit the greatest increases in support for gay and lesbian civil rights. We observed hypothesized shifts in SO beliefs across all experimental conditions. While there was a small main effect of time on homonegative prejudice, there was no main effect of condition and no changes in support for gay and lesbian civil rights. However, post hoc analyses suggested the two conditions addressing social constructionist beliefs accounted for most of the observed prejudice reduction. Implications for more comprehensive educational and social interventions designed to promote social justice for sexual minorities are discussed.

What Does "Couple" Mean in Couple Therapy Outcome Research? A Systematic Review of the Implicit and Explicit, Inclusion and Exclusion of Gender and Sexual Minority Individuals and Identities.

This study systematically reviewed extant couple therapy outcome studies (k = 111) through December 2018 to evaluate for implicit or explicit, inclusion or exclusion of gender and/or sexual minority individuals and identities. We evaluated sampling, participant demographic reporting, and language used in each manuscript for any reference or consideration given to participants' sexual and/or gender identity. Results indicate that couples have been historically presumed to be heterosexual and cisgender male or female without reported assessment. More recent inclusion and consideration of sexual minority individuals is limited and absent for nonmonosexual and gender minority individuals. These findings are contextualized in supplementary analyses of other sociocultural characteristics (e.g., race, age, length together). Suggestions are provided for affirmative consideration of the plurality of individuals' sexual and gender identities. Implications are discussed for research, training and practice of couple therapy with sexual and/or gender minority couples.

Conscience clauses and sexual and gender minority mental health care: A case study.

Tennessee is one of the first states in the United States to have a law that enables counselors and therapists in independent practice to deny services to any client based on the practitioner's "sincerely held principles." This so-called "conscience clause" represents a critical moment in professional psychology, in which mental health care providers are on the frontlines of cultural and legal debates about religious freedom. Though the law's language is ambiguous, it was widely perceived to target sexual and gender minority (SGM) individuals. We interviewed 20 SGM people living in Tennessee to understand their experiences with mental health care in the state and their perceptions of the law. Our participants perceive the law as fundamentally discriminatory, though they overwhelmingly conceptualize the conscience clause as legalizing discrimination toward members of all stigmatized groups-not just SGM individuals. They described individual and societal consequences for the law, including an understanding of the conscience clause as harmful above and beyond any individual discrimination event it may engender. We situate these findings amid the research on structural stigma and suggest that counseling psychologists become actively engaged in combatting conscience clauses, which appear to have profound consequences on mental health care engagement, particularly for populations vulnerable to discrimination. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Dual-energy X-ray Absorptiometry Monitoring with Trabecular Bone Score: 2019 ISCD Official Position.

Trabecular bone score (TBS) is a textural index that evaluates pixel gray-level variations in the lumbar spine image by dual-energy X-ray absorptiometry. It provides an indirect assessment of trabecular microarchitecture that is an independent predictor of fracture risk. TBS does not appear to be clinically useful to monitor the skeletal effects of bisphosphonates and denosumab, but is potentially useful as a component of monitoring the skeletal effects of teriparatide and abaloparatide. The least significant change (LSC) for TBS can be conservatively estimated to be about 5.8% (the largest LSC in published data) or calculated by a dual-energy X-ray absorptiometry facility using the same methodology that is used for bone mineral density (BMD) precision assessment to calculate BMD LSC. A review of the best available evidence at the 2019 ISCD Position Development Conference concluded that the role of TBS in monitoring antiresorptive therapy is unclear and that TBS is potentially useful for monitoring anabolic therapy. For patients treated with teriparatide or abaloparatide, a statistically significant increase in TBS may represent a clinically meaningful improvement in trabecular structure. A significant decrease of TBS may represent a worsening of trabecular structure, suggesting the need for further clinical assessment and possible change in treatment strategies. Since BMD measures bone quantity and TBS measures bone quality, these tests can be considered complementary in assessing fracture risk and response to therapy in appropriate patients.

First evidence of Kunjin strain of West Nile virus associated with saltwater crocodile (Crocodylus porosus) skin lesions.

Recently, the Kunjin strain of West Nile virus (WNVKUN ) has been detected using qRT-PCR in belly skin lesions of farmed juvenile saltwater crocodiles. This follows an established association between similar lesions and West Nile virus in American alligators. The lesions present as cutaneous lymphohistiocytic aggregates in the dermal layers of both species. While these lesion do not create an obvious defect on the live crocodile, upon tanning the lesion area collapses and does not uptake the dye evenly, thus reducing its aesthetic appeal. As a result, skins are being rejected jeopardising the economic viability of the Australian crocodile industry. Over 50 skin lesions have since been confirmed as WNVKUN -positive and preliminary evidence of lesion restructuring is presented. Horizontal transmission of WNVKUN by mosquitoes is well-established but other transmission routes, such as ingestion and cloacal shedding, need further evaluation. An infection trial is currently underway to ensure WNVKUN is the causative agent of these skin lesions.

Prevalence of and Characteristics Associated With Self-reported Good Hearing in a Population With Elevated Audiometric Thresholds.

Importance: Audiometric evidence of hearing loss does not always relate to self-reported hearing loss. Objective: To determine the prevalence of self-reported good hearing in a population with audiometrically defined hearing loss and identify associated factors. Design, Setting, and Participants: We analyzed audiometric data from adults aged 20 to 69 years from the 1999 to 2002 cycles of the US National Health and Nutrition Examination Survey, a cross-sectional, nationally representative interview and examination survey of the civilian, noninstitutionalized population. Logistic regression was used to examine unadjusted and multivariable-adjusted relationships between demographic, hearing health, and general health factors related to self-perceived hearing status. Analysis was conducted between September 4, 2018, and November 30, 2018. Interventions: Audiometry and questionnaires. Main Outcomes and Measure: The prevalence of persons reporting good hearing among those with audiometrically defined hearing loss and the variables associated with this population. Results: The mean (SD) age was 47.0 (0.4) years for hearing loss defined by any frequency >25 dB HL and 52.5 (1.1) years for hearing loss defined by PTA >25 dB HL. For the sample with hearing loss defined by any frequency >25 dB HL, 744 (56.1%) were men and 629 (43.9%) were women. For the sample with hearing loss defined by PTA >25 dB HL 251 (68.5%) were men and 114 (31.5%) were women. Of the 1373 participants who were found to have hearing loss (at least 1 individual frequency >25 dB HL in either ear) 993 (68.5%) reported good hearing. Younger age, nonwhite race, and women were all more likely to report good hearing. When the definition of hearing loss was made more stringent (pure-tone average >25 dB HL), 365 participants had audiometric hearing loss, but 174 (43%) continued to report good hearing. We observed that better self-perceived general health status (OR, 1.90; 95% CI, 1.25-2.90) and higher dietary quality (OR, 1.01; 95% CI, 1.00-1.02) were significantly associated with increased self-report of good hearing, whereas tinnitus (OR, 0.25; 95% CI, 0.14-0.44), noise exposure (OR, 0.39; 95% CI, 0.26-0.58), and several comorbid conditions were associated with decreased self-report of good hearing. Conclusions and Relevance: A significant proportion of the study population reported good hearing despite having audiometric evidence of hearing loss; the prevalence was related to how hearing loss was defined. The report of good hearing was significantly associated with demographics and general health status. The high prevalence of mild hearing loss and self-reported good hearing was associated with the low reported use of hearing aids.

Leadership capabilities of physiotherapy leaders in Ireland: Part 2. Clinical specialists and advanced physiotherapy practitioners.

Background: Investigation of the leadership capabilities of physiotherapy managers found that they report predominantly demonstrating capabilities associated with the human resource and structural frames. However, little is known about the leadership capabilities of clinical specialists and advanced physiotherapy practitioners (APPs) who also are identified as having responsibility for leadership. Objective: To explore clinical specialists´ and APPs' perceptions of their leadership capabilities and compare them with the reported leadership capabilities of physiotherapy managers. Methods: Semi-structured interviews were conducted with a purposive sample of 17 physiotherapy clinical specialists and APPs from a range of practice settings across Ireland. The interviews were analyzed using template analysis and the coding template was based on the Bolman and Deal Leadership framework. Results: The participants described demonstrating leadership capabilities associated with each of the four leadership frames. However, the language used by the clinical specialists/APPs suggested that they work predominantly through the human resource frame. Structural frame capabilities were reported by the clinical specialists/APPs and there were some differences to those reported by the managers. In keeping with the reported leadership capabilities of the physiotherapy managers, the employment of capabilities associated with the political frame varied between participants and symbolic frame capabilities were underused. Conclusion: There are many similarities in the self-reported leadership capabilities of managers and clinical specialists/APPs. However, differences were also noted. Both cohorts of physiotherapy leaders may benefit from specific development programs to develop leadership capabilities associated with the political and symbolic frames.

Non-BMD DXA measurements of the hip.

Hip fracture is one of the most serious complications of osteoporosis. More than 50% of hip and other fractures occur in patients without densitometric osteoporosis. Therefore, areal bone mineral density (aBMD) may not be the best way to assess fracture risk. In order to improve assessment of fracture risk, many other approaches have been taken. At the present time, the Fracture Risk Algorithm (FRAX©) is one of the most notable ways to improve assessment of fracture risk. However, since early in the initiation of the dual energy x-ray absorptiometry (DXA) era, several non-BMD DXA approaches to the assessment of hip fracture risk have been proposed. This review will cover some of those methodologies, including hip-axis length (HAL), hip-structural analysis (HSA), finite element analysis (FEA) by DXA, and body composition of the thigh by DXA (BCT). These methods have been utilized in models of hip fracture occurrence and in pharmacological clinical trials. How they should be used in clinical practice or if they should be used in clinical practice is more of an issue. In addition, we will discuss the recent proposal of the use of Long Femur Scan Field in the effort to diagnose atypical femoral fractures.

Application of Pheromone Traps for Managing Hessian Fly (Diptera: Cecidomyiidae) in the Southern Great Plains.

The Hessian fly, Mayetiola destructor Say, is an important pest of winter wheat in the Southern Great Plains of the United States. As larvae feed behind the leaf sheath, infestations often go undetected until crop damage is evident, and there are no remedial actions that can prevent economic loss once a field is infested. The recent discovery of the sex-attractant pheromone of the Hessian fly provides an opportunity to use pheromone traps to detect and monitor adult activity and potentially better manage this pest. Adult male Hessian fly activity was monitored during 4 yr at six locations from northcentral Oklahoma, 36° N latitude, south to central Texas, 31° N latitude. In Oklahoma, trap captures were low in the fall, no flies were captured during the winter, and the largest number of flies was captured in the spring. However, in southcentral Texas, adults were captured throughout the fall, winter, and in the spring when trap captures were again the greatest. The relationship between trap captures and density of Hessian fly larvae per tiller was investigated during the fall and spring. Although large numbers of adults (>100 per trap per day) were often captured, economic infestation of larvae rarely developed. Results identify optimum times for field sampling to determine immature Hessian fly infestations in wheat in Oklahoma and Texas.

Post-viraemic detection of bovine ephemeral fever virus by use of autogenous lymphoid tissue-derived bovine primary cell cultures.

BACKGROUND: The potential tissue replication sites and specific cell types that support in vivo virus survival beyond the acute phase of bovine ephemeral fever virus (BEFV) infection have not been fully defined in cattle. To clarify the knowledge gap, tissue specimens were tested after collection from an adult steer necropsied 1 week after acute BEF. CASE REPORT: Significant necropsy findings included fibrinoproliferative synovitis in the stifle joints and fibrin clot-laden fluid in serous body cavities. Moderate numbers of infiltrating neutrophils were demonstrated in sections of the prefemoral lymph nodes and haemal node, and lymphoid hyperplasia in the spleen, haemal node and prefemoral lymph nodes. Viral RNA was detected by qRT-PCR in fresh spleen, haemal node, prefemoral lymph node, synovial fluid and in several spleen-derived cell cultures. BEFV was isolated from autogenously derived splenic primary cell cultures 6 days after cessation of viraemia, and characteristic bullet-shaped virions were confirmed by electron microscopy of an ultrathin haemal node section. In sections of the spleen, haemal node and other tissues, immunohistochemistry demonstrated BEFV antigens that were intracellularly associated with probable histiocytic cells. CONCLUSION: BEFV has preferential tropism for bovine lymphoid tissues and the spleen and haemal node may be potential sites for post-viraemic virus replication.

Viral neurotropism, peripheral neuropathy and other morphological abnormalities in bovine ephemeral fever virus-infected downer cattle.

OBJECTIVE: This study assessed the neurotropism of bovine ephemeral fever (BEF) virus (BEFV) and described histomorphological abnormalities of the brain, spinal cord and peripheral nerves that may causally contribute to paresis or paralysis in BEF. METHODS: Four paralysed and six asymptomatic but virus-infected cattle were monitored, and blood and serum samples screened by qRT-PCR, virus isolation and neutralisation tests. Fresh brain, spinal cord, peripheral nerve and other tissues were qRT-PCR-tested for viral RNA, while formalin-fixed specimens were processed routinely and immunohistochemically evaluated for histomorphological abnormalities and viral antigen distribution, respectively. RESULTS: The neurotropism of BEFV was immunohistochemically confirmed in the brain and peripheral nerves and peripheral neuropathy was demonstrated in three paralysed but not the six aneurological but virus-infected animals. Wallerian degeneration (WD) was present in the ventral funicular white matter of the lumbar spinal cord of a paralysed steer and in cervical and thoracic spinal cord segments of three paralysed animals. Although no spinal cord lesions were seen in the steer euthanased within 7 days of illness, peripheral neuropathy was present and more severe in nerves of the brachial plexuses than in the gluteal or fibular nerves. The only steer with WD in the lumbar spinal cord also showed intrahistiocytic cell viral antigen that was spatially distributed within areas of moderate brain stem encephalitis. CONCLUSION: The data confirmed neurotropism of BEFV in cattle and documented histomorphological abnormalities in peripheral nerves and brain which, together with spinal cord lesions, may contribute to chronic paralysis in BEFV-infected downer cattle.

NDVI to Detect Sugarcane Aphid Injury to Grain Sorghum.

Multispectral remote sensing has potential to provide quick and inexpensive information on sugarcane aphid, Melanaphis sacchari (Zehntner), pest status in sorghum fields. We describe a study conducted to determine if injury caused by sugarcane aphid to sorghum plants in fields of grain sorghum could be detected using multispectral remote sensing from a fixed wing aircraft. A study was conducted in commercial grain sorghum fields in the Texas Gulf Coast region in June 2014. Twenty-six commercial grain sorghum fields were selected and rated for the level of injury to sorghum plants in the field caused by sugarcane aphid. Plant growth stage ranged from 5.0 (watery ripe) to 7.0 (hard dough) among fields; and plant injury rating from sugarcane aphid ranged from 1.0 (little or no injury) to 4.0 (>40% of plants displaying injury) among fields. The normalized differenced vegetation index (NDVI) is calculated from light reflectance in the red and near-infrared wavelength bands in multispectral imagery and is a common index of plant stress. High NDVI indicates low levels of stress and low NDVI indicates high stress. NDVI ranged from -0.07 to 0.26 among fields. The correlation between NDVI and plant injury rating was negative and significant, as was the correlation between NDVI and plant growth stage. The negative correlation of NDVI with injury rating indicated that plant stress increased with increasing plant injury. Reduced NDVI with increasing plant growth probably resulted from reduced photosynthetic activity in more mature plants. The correlation between plant injury rating and plant growth stage was positive and significant indicating that plant injury from sugarcane aphid increased as plants matured. The partial correlation of NDVI with plant injury rating was negative and significant indicating that NDVI decreased with increasing plant injury after adjusting for its association with plant growth stage. We demonstrated that remotely sensed imagery acquired from grain sorghum fields using an airborne multi-spectral imaging system was sensitive to injury to sorghum plants caused by sugarcane aphid.

Sequential sampling for panicle caterpillars (Lepidoptera: Noctuidae) in sorghum.

Panicle caterpillars comprise an economically important insect pest complex of sorghum throughout the Great Plains of the United States, particularly in Kansas, Oklahoma, and Texas. The sorghum panicle caterpillar complex consists of larvae of two polyphagous lepidopteran species: the corn earworm, Helicoverpa zea (Boddie), and fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). Sampling for panicle caterpillars in sorghum fields is usually accomplished by the beat bucket sampling technique with a fixed sample size of 30 beat bucket samples of one sorghum panicle each per 16.2 ha of field. We used Wald's sequential probability ratio test for a negative binomial distribution to develop a sequential sampling plan for panicle caterpillars. In total, 115 sorghum fields were sampled in Kansas, Oklahoma, and Texas from June to August 2010. Panicle caterpillars had an aggregated distribution of counts confirmed by Pearson's chi-square statistic for lack of fit to the negative binomial distribution for each sampled field. A sequential sampling plan was developed using a high threshold (an economic threshold) of 0.5 caterpillars per sorghum panicle, a low threshold (a safe level) of 0.20 caterpillars per panicle, and fixed error rates (alpha = 0.10 and beta = 0.05). At caterpillar densities > 0.45 and < 0.12 per panicle, the average number of panicles inspected to make a decision was less than the current recommendation of 30. In a 2013 validation test of 25 fields, the expected number of samples taken from average sample number curve was in close agreement with the number of samples required using the sequential plan (r2 = 0.93), and all fields were correctly classified when compared with a fixed sample size result. The plan improved upon current sampling recommendations for panicle caterpillars in sorghum because at known acceptable fixed error rates fewer samples were required when caterpillars are scarce or abundant, whereas more samples were required to make decisions with the same acceptable error rates when densities were near the economic thresholds.

Evidence for multiple sex-determining loci in Tasmanian Atlantic salmon (Salmo salar).

Phenotypic sex in salmonids is determined primarily by a genetic male heterogametic system; yet, sex reversal can be accomplished via hormonal treatment. In Tasmanian Atlantic salmon aquaculture, to overcome problems associated with early sexual maturation in males, sex-reversed females are crossed with normal females to produce all female stock. However, phenotypic distinction of sex-reversed females (neo-males) from true males is problematic. We set out to identify genetic markers that could make this distinction. Microsatellite markers from chromosome 2 (Ssa02), to which the sex-determining locus (SEX) has been mapped in two Scottish Atlantic salmon families, did not predict sex in a pilot study of seven families. A TaqMan 64 SNP genome-wide scan suggested SEX was on Ssa06 in these families, and this was confirmed by microsatellite markers. A survey of 58 families in total representing 38 male lineages in the SALTAS breeding program found that 34 of the families had SEX on Ssa02, in 22 of the families SEX was on Ssa06, and two of the families had a third SEX locus, on Ssa03. A PCR test using primers designed from the recently published sdY gene is consistent with Tasmanian Atlantic salmon having a single sex-determining gene that may be located on at least three linkage groups.

Syrinx fluid transport: modeling pressure-wave-induced flux across the spinal pial membrane.

Syrinxes are fluid-filled cavities of the spinal cord that characterize syringomyelia, a disease involving neurological damage. Their formation and expansion is poorly understood, which has hindered successful treatment. Syrinx cavities are hydraulically connected with the spinal subarachnoid space (SSS) enveloping the spinal cord via the cord interstitium and the network of perivascular spaces (PVSs), which surround blood vessels penetrating the pial membrane that is adherent to the cord surface. Since the spinal canal supports pressure wave propagation, it has been hypothesized that wave-induced fluid exchange across the pial membrane may play a role in syrinx filling. To investigate this conjecture a pair of one-dimensional (1-d) analytical models were developed from classical elastic tube theory coupled with Darcy's law for either perivascular or interstitial flow. The results show that transpial flux serves as a mechanism for damping pressure waves by alleviating hoop stress in the pial membrane. The timescale ratio over which viscous and inertial forces compete was explicitly determined, which predicts that dilated PVS, SSS flow obstructions, and a stiffer and thicker pial membrane-all associated with syringomyelia-will increase transpial flux and retard wave travel. It was also revealed that the propagation of a pressure wave is aided by a less-permeable pial membrane and, in contrast, by a more-permeable spinal cord. This is the first modeling of the spinal canal to include both pressure-wave propagation along the spinal axis and a pathway for fluid to enter and leave the cord, which provides an analytical foundation from which to approach the full poroelastic problem.

Stress fractures about the tibia, foot, and ankle.

In competitive athletes, stress fractures of the tibia, foot, and ankle are common and lead to considerable delay in return to play. Factors such as bone vascularity, training regimen, and equipment can increase the risk of stress fracture. Management is based on the fracture site. In some athletes, metabolic workup and medication are warranted. High-risk fractures, including those of the anterior tibial diaphysis, navicular, proximal fifth metatarsal, and medial malleolus, present management challenges and may require surgery, especially in high-level athletes who need to return to play quickly. Noninvasive treatment modalities such as pulsed ultrasound and extracorporeal shock wave therapy may have some benefit but require additional research.