Effects of chemical releases by the STS-3 Orbiter on the ionosphere

The Plasma Diagnostics Package, flown aboard STS-3 as part of the first Shuttle payload (OSS-1), recorded the effects of various chemical releases from the Orbiter. Changes in the plasma environment was observed during flash evaporator system releases, water dumps and maneuvering thruster operations. During flash evaporator operations, broadband Orbiter-generated electrostatic noise was enhanced and plasma density irregularities were observed to increase by 3 to 30 times with a spectrum which rose steeply and peaked below 6 Hz. In the case of water dumps, background electrostatic noise was enhanced at frequencies below about 3 kHz and suppressed at frequencies above 2 kHz. Thruster activity also stimulated electrostatic noise with a spectrum which peaked at approximately 0.5 kHz. In addition, ions with energies up to 1 keV were seen during some thruster events

Simulation study of the interaction between large-amplitude HF radio waves and the ionosphere

The time evolution of a large-amplitude electromagnetic (EM) wave injected vertically into the overhead ionosphere is studied numerically. The EM wave has a carrier frequency of 5 MHz and is modulated as a Gaussian pulse with a width of approximately 0.1 milliseconds and a vacuum amplitude of 1.5 V/m at 50 km. This is a fair representation of a modulated radio wave transmitted from a typical high-power HF broadcast station on the ground. The pulse is propagated through the neutral atmosphere to the critical points of the ionosphere, where the L-O and R-X modes are reflected, and back to the neutral atmosphere. We observe mode conversion of the L-O mode to electrostatic waves, as well as harmonic generation at the turning points of both the R-X and L-O modes, where their amplitudes rise to several times the original ones. The study has relevance for ionospheric interaction experiments in combination with ground-based and satellite or rocket observations.Comment: 6 pages, 7 figure

Beyond spinal manipulation: should Medicare expand coverage for chiropractic services? A review and commentary on the challenges for policy makers

Objectives: Private insurance plans typically reimburse doctors of chiropractic for a range of clinical services, but Medicare reimbursements are restricted to spinal manipulation procedures. Medicare pays for evaluations performed by medical and osteopathic physicians, nurse practitioners, physician assistants, podiatrists, physical therapists, and occupational therapists; however, it does not reimburse the same services provided by chiropractic physicians. Advocates for expanded coverage of chiropractic services under Medicare cite clinical effectiveness and patient satisfaction, whereas critics point to unnecessary services, inadequate clinical documentation, and projected cost increases. To further inform this debate, the purpose of this commentary is to address the following questions: (1) What are the barriers to expand coverage for chiropractic services? (2) What could potentially be done to address these issues? (3) Is there a rationale for Centers for Medicare and Medicaid Services to expand coverage for chiropractic services? Methods: A literature search was conducted of Google and PubMed for peer-reviewed articles and US government reports relevant to the provision of chiropractic care under Medicare. We reviewed relevant articles and reports to identify key issues concerning the expansion of coverage for chiropractic under Medicare, including identification of barriers and rationale for expanded coverage. Results: The literature search yielded 29 peer-reviewed articles and 7 federal government reports. Our review of these documents revealed 3 key barriers to full coverage of chiropractic services under Medicare: inadequate documentation of chiropractic claims, possible provision of unnecessary preventive care services, and the uncertain costs of expanded coverage. Our recommendations to address these barriers include the following: individual chiropractic physicians, as well as state and national chiropractic organizations, should continue to strengthen efforts to improve claims and documentation practices; and additional rigorous efficacy/effectiveness research and clinical studies for chiropractic services need to be performed. Research of chiropractic services should target the triple aim of high-quality care, affordability, and improved health. Conclusions: The barriers that were identified in this study can be addressed. To overcome these barriers, the chiropractic profession and individual physicians must assume responsibility for correcting deficiencies in compliance and documentation; further research needs to be done to evaluate chiropractic services; and effectiveness of extended episodes of preventive chiropractic care should be rigorously evaluated. Centers for Medicare and Medicaid Services policies related to chiropractic reimbursement should be reexamined using the same standards applicable to other health care providers. The integration of chiropractic physicians as fully engaged Medicare providers has the potential to enhance the capacity of the Medicare workforce to care for the growing population. We recommend that Medicare policy makers consider limited expansion of Medicare coverage to include, at a minimum, reimbursement for evaluation and management services by chiropractic physicians

Characteristics of US Adults Who Have Positive and Negative Perceptions of Doctors of Chiropractic and Chiropractic Care

AbstractObjectiveThe purpose of this study was to compare characteristics, likelihood to use, and actual use of chiropractic care for US survey respondents with positive and negative perceptions of doctors of chiropractic (DCs) and chiropractic care.MethodsFrom a 2015 nationally representative survey of 5422 adults (response rate, 29%), we used respondents' answers to identify those with positive and negative perceptions of DCs or chiropractic care. We used the χ2 test to compare other survey responses for these groups.ResultsPositive perceptions of DCs were more common than those for chiropractic care, whereas negative perceptions of chiropractic care were more common than those for DCs. Respondents with negative perceptions of DCs or chiropractic care were less likely to know whether chiropractic care was covered by their insurance, more likely to want to see a medical doctor first if they were experiencing neck or back pain, less likely to indicate that they would see a DC for neck or back pain, and less likely to have ever seen a DC as a patient, particularly in the recent past. Positive perceptions of chiropractic care and negative perceptions of DCs appear to have greater influence on DC utilization rates than their converses.ConclusionWe found that US adults generally perceive DCs in a positive manner but that a relatively high proportion has negative perceptions of chiropractic care, particularly the costs and number of visits required by such care. Characteristics of respondents with positive and negative perceptions were similar, but those with positive perceptions were more likely to plan to use—and to have already received—chiropractic care

4,6-Bis(diphenyl­phosphan­yl)-2,8-di­methyl­phenoxathiin dichloro­methane monosolvate

The title compound, C38H30OP2S·CH2Cl2, belongs to the xanthene family of ligands containing S- and O-donor atoms in the central heterocylic ring. Positions 2 and 8 on the xanthene backbone are functionalized with methyl groups to allow for the selective functionalization of the backbone at positions 4 and 6 with diphenyl­phosphanyl units. The title compound shows a significant ‘roof-like’ bending along the axis of planarity involving the O- and S-donor atoms and the benzene rings, resulting in a dihedral angle between the mean planes of the benzene rings of 32.88 (13)°

Necessary Condition Analysis (NCA) Does Exactly What It Should Do When Applied Properly: A Reply to a Comment on NCA

There are two problems with the comment of Thiem about necessary condition analysis (NCA): First, it is based on wrong assumptions about what NCA aims to do. Second, it applies NCA incorrectly. These are critical errors such that the comment’s conclusions about NCA are flawed. Contrary to what the comment states, NCA is a valid method for identifying necessary conditions

Geographical location influences the composition of the gut microbiota in wild house mice (Mus musculus domesticus) at a fine spatial scale.

The composition of the mammalian gut microbiota can be influenced by a multitude of environmental variables such as diet and infections. Studies investigating the effect of these variables on gut microbiota composition often sample across multiple separate populations and habitat types. In this study we explore how variation in the gut microbiota of the house mouse (Mus musculus domesticus) on the Isle of May, a small island off the east coast of Scotland, is associated with environmental and biological factors. Our study focuses on the effects of environmental variables, specifically trapping location and surrounding vegetation, as well as the host variables sex, age, body weight and endoparasite infection, on the gut microbiota composition across a fine spatial scale in a freely interbreeding population. We found that differences in gut microbiota composition were significantly associated with the trapping location of the host, even across this small spatial scale. Sex of the host showed a weak association with microbiota composition. Whilst sex and location could be identified as playing an important role in the compositional variation of the gut microbiota, 75% of the variation remains unexplained. Whereas other rodent studies have found associations between gut microbiota composition and age of the host or parasite infections, the present study could not clearly establish these associations. We conclude that fine spatial scales are important when considering gut microbiota composition and investigating differences among individuals

But Not Both:The Exclusive Disjunction in Qualitative Comparative Analysis (QCA)

The application of Boolean logic using Qualitative Comparative Analysis (QCA) is becoming more frequent in political science but is still in its relative infancy. Boolean ‘AND’ and ‘OR’ are used to express and simplify combinations of necessary and sufficient conditions. This paper draws out a distinction overlooked by the QCA literature: the difference between inclusive- and exclusive-or (OR and XOR). It demonstrates that many scholars who have used the Boolean OR in fact mean XOR, discusses the implications of this confusion and explains the applications of XOR to QCA. Although XOR can be expressed in terms of OR and AND, explicit use of XOR has several advantages: it mirrors natural language closely, extends our understanding of equifinality and deals with mutually exclusive clusters of sufficiency conditions. XOR deserves explicit treatment within QCA because it emphasizes precisely the values that make QCA attractive to political scientists: contextualization, confounding variables, and multiple and conjunctural causation