Positive operators and a problem in control theory

Casanovas, Fernando; Obradors, Víctor; Busquets, Josep M

Mycobacterium sp. as a possible cause of hypersensitivity pneumonitis in machine workers.

Hypersensitivity pneumonitis (HP) in workers exposed to metal removal fluids (MRFs) is increasing. This study supports the hypothesis that aerosolized mycobacteria colonizing the MRFs likely cause the disease. Three case studies of HP outbreaks among metal workers showed potentially high exposures to a rare and newly proposed Mycobacterium species. Retrospective review of samples submitted to our laboratory showed an association between presence of mycobacteria and HP

Photon deflection and precession of the periastron in terms of spatial gravitational fields

We show that a Maxwell-like system of equations for spatial gravitational fields $\bf g$ and $\bf B$ (latter being the analogy of a magnetic field), modified to include an extra term for the $\bf B$ field in the expression for force, leads to the correct values for the photon deflection angle and for the precession of the periastron

On the Theory of Superfluidity in Two Dimensions

The superfluid phase transition of the general vortex gas, in which the circulations may be any non-zero integer, is studied. When the net circulation of the system is not zero the absence of a superfluid phase is shown. When the net circulation of the vortices vanishes, the presence of off-diagonal long range order is demonstrated and the existence of an order parameter is proposed. The transition temperature for the general vortex gas is shown to be the Kosterlitz---Thouless temperature. An upper bound for the average vortex number density is established for the general vortex gas and an exact expression is derived for the Kosterlitz---Thouless ensemble.Comment: 22 pages, one figure, written in plain TeX, published in J. Phys. A24 (1991) 502

Tried and true: A survey of successfully promoted academic hospitalists

BACKGROUND: Academic hospital medicine is a new and rapidly growing field. Hospitalist faculty members often fill roles not typically held by other academic faculty, maintain heavy clinical workloads, and participate in nontraditional activities. Because of these differences, there is concern about how academic hospitalists may fare in the promotions process. OBJECTIVE: To determine factors critical to the promotion of successfully promoted hospitalists who have achieved the rank of either associate professor or professor. DESIGN: A cross‐sectional survey. PARTICIPANTS: Thirty‐three hospitalist faculty members at 22 academic medical centers promoted to associate professor rank or higher between 1995 and 2008. MEASUREMENTS: Respondents were asked to describe their institution, its promotions process, and the activities contributing to their promotion. We identified trends across respondents. RESULTS: Twenty‐six hospitalists responded, representing 20 institutions (79% response rate). Most achieved promotion in a nontenure track (70%); an equal number identified themselves as clinician‐administrators and clinician educators (40%). While hospitalists were engaged in a wide range of activities in the traditional domains of service, education, and research, respondents considered peer‐reviewed publication to be the most important activity in achieving promotion. Qualitative responses demonstrated little evidence that being a hospitalist was viewed as a hindrance to promotion. CONCLUSIONS: Successful promotion in academic hospital medicine depends on accomplishment in traditional academic domains, raising potential concerns for academic hospitalists with less traditional roles. This study may provide guidance for early‐career academic hospitalists and program leaders. Journal of Hospital Medicine 2011. © 2011 Society of Hospital MedicinePeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86910/1/894_ftp.pd

Human norovirus infection and the acute serum cytokine response

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/115914/1/cei12681.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/115914/2/cei12681_am.pd

Electrodynamics with Lorentz-violating operators of arbitrary dimension

The behavior of photons in the presence of Lorentz and CPT violation is studied. Allowing for operators of arbitrary mass dimension, we classify all gauge-invariant Lorentz- and CPT-violating terms in the quadratic Lagrange density associated with the effective photon propagator. The covariant dispersion relation is obtained, and conditions for birefringence are discussed. We provide a complete characterization of the coefficients for Lorentz violation for all mass dimensions via a decomposition using spin-weighted spherical harmonics. The resulting nine independent sets of spherical coefficients control birefringence, dispersion, and anisotropy. We discuss the restriction of the general theory to various special models, including among others the minimal Standard-Model Extension, the isotropic limit, the case of vacuum propagation, the nonbirefringent limit, and the vacuum-orthogonal model. The transformation of the spherical coefficients for Lorentz violation between the laboratory frame and the standard Sun-centered frame is provided. We apply the results to various astrophysical observations and laboratory experiments. Astrophysical searches of relevance include studies of birefringence and of dispersion. We use polarimetric and dispersive data from gamma-ray bursts to set constraints on coefficients for Lorentz violation involving operators of dimensions four through nine, and we describe the mixing of polarizations induced by Lorentz and CPT violation in the cosmic-microwave background. Laboratory searches of interest include cavity experiments. We present the theory for searches with cavities, derive the experiment-dependent factors for coefficients in the vacuum-orthogonal model, and predict the corresponding frequency shift for a circular-cylindrical cavity.Comment: 58 pages two-column REVTeX, accepted in Physical Review

Association of Infectious Disease Physician Approval of Peripherally Inserted Central Catheter With Appropriateness and Complications

Importance: Peripherally inserted central catheters (PICCs) are frequently used to deliver intravenous antimicrobial therapy. However, inappropriate PICC use may lead to patient harm. Objective: To evaluate whether infectious disease physician approval prior to PICC placement for intravenous antimicrobials is associated with more appropriate device use and fewer complications. Design, Setting, and Participants: This cohort study of 21 653 PICCs placed for a primary indication of intravenous antimicrobial therapy between January 1, 2015, and July 26, 2019, was conducted in 42 hospitals participating in a quality collaborative across Michigan among hospitalized medical patients. Main Outcomes and Measures: Appropriateness of PICCs was defined according to the Michigan Appropriateness Guide for Intravenous Catheters as a composite measure of (1) single-lumen catheter use, (2) avoiding use of PICCs for 5 days or less, and (3) avoiding use of PICCs for patients with chronic kidney disease (defined as an estimated glomerular filtration rate/min/1.73 m2). Complications related to PICCs included catheter occlusion, deep vein thrombosis, and central line-associated bloodstream infection. The association between infectious disease physician approval, device appropriateness, and catheter complications was assessed using multivariable models, adjusted for patient comorbidities and hospital clustering. Results were expressed as odds ratios with 95% CIs. Results: A total of 21 653 PICCs were placed for intravenous antimicrobials (11 960 PICCs were placed in men [55.2%]; median age, 64.5 years [interquartile range, 53.4-75.4 years]); 10 238 PICCs (47.3%) were approved by an infectious disease physician prior to placement. Compared with PICCs with no documented approval, PICCs with approval by an infectious disease physician were more likely to be appropriately used (72.7% [7446 of 10 238] appropriate with approval vs 45.4% [5180 of 11 415] appropriate without approval; odds ratio, 3.53; 95% CI, 3.29-3.79; P \u3c .001). Furthermore, approval was associated with lower odds of a PICC-related complication (6.5% [665 of 10 238] with approval vs 11.3% [1292 of 11 415] without approval; odds ratio, 0.55; 95% CI, 0.50-0.61). Conclusions and Relevance: This cohort study suggests that, when PICCs were placed for intravenous antimicrobial therapy, infectious disease physician approval of PICC insertion was associated with more appropriate device use and fewer complications. Policies aimed at ensuring infectious disease physician approval prior to PICC placement for antimicrobials may improve patient safety

Antibiotic stewardship teams and Clostridioides difficile practices in United States hospitals: A national survey in The Joint Commission antibiotic stewardship standard era

OBJECTIVE: Clostridioides difficile infection (CDI) can be prevented through infection prevention practices and antibiotic stewardship. Diagnostic stewardship (ie, strategies to improve use of microbiological testing) can also improve antibiotic use. However, little is known about the use of such practices in US hospitals, especially after multidisciplinary stewardship programs became a requirement for US hospital accreditation in 2017. Thus, we surveyed US hospitals to assess antibiotic stewardship program composition, practices related to CDI, and diagnostic stewardship. METHODS: Surveys were mailed to infection preventionists at 900 randomly sampled US hospitals between May and October 2017. Hospitals were surveyed on antibiotic stewardship programs; CDI prevention, treatment, and testing practices; and diagnostic stewardship strategies. Responses were compared by hospital bed size using weighted logistic regression. RESULTS: Overall, 528 surveys were completed (59% response rate). Almost all (95%) responding hospitals had an antibiotic stewardship program. Smaller hospitals were less likely to have stewardship team members with infectious diseases (ID) training, and only 41% of hospitals met The Joint Commission accreditation standards for multidisciplinary teams. Guideline-recommended CDI prevention practices were common. Smaller hospitals were less likely to use high-tech disinfection devices, fecal microbiota transplantation, or diagnostic stewardship strategies. CONCLUSIONS: Following changes in accreditation standards, nearly all US hospitals now have an antibiotic stewardship program. However, many hospitals, especially smaller hospitals, appear to struggle with access to ID expertise and with deploying diagnostic stewardship strategies. CDI prevention could be enhanced through diagnostic stewardship and by emphasizing the role of non-ID-trained pharmacists and clinicians in antibiotic stewardship