Modulation of Isomerization and Ligand Exchange Rates by π Bonding in Bis(iminoxolene)iridium Pyridine Complexes.

The bis(iminoxolene)iridium complex (Diso)2IrCl (Diso = N-(2,6-diisopropylphenyl)-4,6-di-tert-butyl-2-imino-o-benzoquinone) reacts with pyridine to give trans-(Diso)2Ir(py)Cl as the kinetic product, with cis-(Diso)2Ir(py)Cl formed as the exclusive thermodynamic product upon heating. Electronic spectra and density functional theory calculations point to very similar electronic structures for the cis and trans isomers, with a nonbonding iminoxolene-centered HOMO and a metal-iminoxolene π* LUMO. The triplet states of cis-(Diso)2Ir(py)Cl and cis-[(Diso)2Ir(py)2]+ (but not trans-(Diso)2Ir(py)Cl) are unusually low in energy (1000-1500 cm-1 above the singlets), as shown by variable-temperature NMR spectroscopy. The low-energy triplets are attributed to a change in dihedral angle in the iminoxolenes, which allows a partial π interaction that cannot be achieved in the trans octahedral compounds. Mechanistic studies of the trans-cis isomerization in toluene indicate that the reaction proceeds via isomerization of the five-coordinate species to a form with cis iminoxolene ligands and an apical oxygen. This form is high in energy due to the loss of a secondary iminoxolene-to-iridium π-donor interaction that is possible in the trans form but not in the cis form for the square pyramidal structures. This stereoelectronic effect, combined with the poorer binding of pyridine in trans-(Diso)2Ir(py)Cl due to the interactions of the N-aryl substituents with the pyridine, makes the pyridine dissociate faster from the trans isomer by a factor of 108 at room temperature.

Mono- and Bis(iminoxolene)iridium Complexes: Synthesis and Covalency in π Bonding.

N-(2,6-Diisopropylphenyl)-4,6-di-tert-butyl-o-iminobenzoquinone (Diso) reacts with the (cyclooctadiene)iridium chloride dimer to form a monoiminoxolene complex, (Diso)Ir(cod)Cl. Reaction of 2 equiv of the iminoquinone with chlorobis(cyclooctene)iridium dimer affords the bis-iminoxolene (Diso)2IrCl. This five-coordinate complex adopts a distorted square pyramidal structure with an apical chloride ligand and undergoes halide exchange to form an air-stable iodide complex. (Diso)2IrCl can be reduced by one electron to form neutral, square planar (Diso)2Ir, while oxidation with PhICl2 gives octahedral trans-(Diso)2IrCl2. The cis isomer can be prepared by air oxidation of (Diso)2IrCl; cis/trans isomerization is not observed even on prolonged heating. Structural and spectroscopic features of the complexes are consistent with the presence of strong, covalent π bonding between the metal and the iminoxolene ligands, with structural data suggesting between 45 and 60% iridium character in the π bonding orbitals, depending on the ancillary ligands. The spectroscopic similarity of (Diso)2Ir and (Diso)2IrCl to their cobalt congeners suggests that the first-row metal complexes likewise have appreciably covalent metal-iminoxolene π bonds.

Before Disaster Strikes: A Pilot Intervention to Improve Pediatric Trainees' Knowledge of Disaster Medicine.

OBJECTIVE: Because training in pediatric disaster medicine (PDM) is neither required nor standardized for pediatric residents, we designed and integrated a PDM course into the curriculum of a pediatric residency program and assessed if participation increased participants' knowledge of managing disaster victims. METHODS: We adapted and incorporated a previously studied PDM course into a small-sized pediatric residency program. The curriculum consisted of didactic lectures and experiential learning via simulation with structured debriefing. With IRB approval, the authors conducted a longitudinal series of pretests and posttests to assess knowledge and perceptions. RESULTS: Sixteen eligible residents completed the intervention. Before the course, none of the residents reported experience treating disaster victims. Pairwise comparison of scores revealed a 35% improvement in scores immediately after completing the course (95% confidence interval, 22.73%-47.26%; P < 0.001) and a 23.73% improvement 2 months later (95% confidence interval, 7.12%-40.34%; P < 0.01). CONCLUSIONS: Residents who completed this course increased their knowledge of PDM with moderate retention of knowledge gained. There was a significant increase in perceived ability to manage patients in a disaster situation after this educational intervention and the residents' confidence was preserved 2 months later. This PDM course may be used in future formulation of a standardized curriculum.

Amphiphilicity in Oxygen Atom Transfer Reactions of Oxobis(iminoxolene)osmium Complexes.

Oxobis(iminoxolene)osmium(VI) compounds (Rap)2OsO (Rap = 2-(4-RC6H4N)-4,6-tBu2C6H2O) are readily deoxygenated by phosphines and phosphites to give five-coordinate (Rap)2Os(PR'3) or six-coordinate (Rap)2Os(PR'3)2. Structural data indicate that this net two-electron reduction is accompanied by apparent oxidation of the iminoxolene ligands due to their greater ability to engage in π donation to the reduced deoxy form of the osmium complex. In (Rap)2Os(PR'3)2, the HOMO is a ligand-based combination of the iminoxolene redox-active orbitals, while the LUMO is a highly covalent metal-iminoxolene π* orbital. In the trans isomer, the HOMO is required to be ligand-localized by symmetry, while in the cis isomer, the ligands adopt a conformation that minimizes metal-ligand π* interactions in the HOMO. Kinetic studies indicate that the deoxygenations involve the rate-determining attack of the phosphorus(III) reagent on the five-coordinate oxo complexes. Varying the substituents of the aryl groups on the iminoxolene ligands or on the triarylphosphines has little effect on the rate of oxygen atom transfer, with the best correlation shown between oxygen atom transfer rates and the HOMO-LUMO gap of the oxo complexes. This suggests that the osmium oxo group shows a balance between electrophilic and nucleophilic character in its oxygen atom transfer reactions with phosphorus(III) reagents.

Continuation of telemedicine in otolaryngology post-COVID-19: Applications by subspecialty.

OBJECTIVE: The purpose of this paper is to review the literature and compile key clinically relevant applications of telemedicine for use in otolaryngology relevant to the post-COVID-19 era. STUDY DESIGN: Systematic Literature Review. DATA SOURCES: Pubmed and Google Scholar. REVIEW METHODS: Pubmed and Google Scholar were queried using combined key words such as "telemedicine," "covid" and "otolaryngology." The searches were completed in March-August 2020. Additional queries were made with particular subspecialty phrases such as "rhinology" or "otology" to maximize yield of relevant titles. Relevant articles were selected for abstract review. Applicable abstracts were then selected for review of the full text. RESULTS: Initial search identified 279 results. These were screened for relevance and 100 abstracts were selected for review. Abstracts were excluded if they were not in English, not related to otolaryngology, or if the full text was unavailable for access. Of these, 37 articles were selected for complete review of the full text. CONCLUSION: The sudden healthcare closures during the COVID-19 pandemic resulted in a sharp increase in the use of telemedicine, particularly in subspecialty fields. Otolaryngologists are at a unique risk of infection resulting from the examination of the head and neck and aerosol-generating procedures due to the predilection of viral particles for the nasal cavities and pharynx. The COVID-19 pandemic may have served as a catalyst to implement telemedicine into clinical practice, however identifying ways to integrate telemedicine long term is key for a sustainable and viable practice in the post-COVID-19 era. Although many states are now finding themselves on the down-sloping side of their infection rate curve, many others remain at the apex. Additionally, the risk of future waves of this pandemic, or the onset of another pandemic, should not be overlooked. Practice modification guidelines that mitigate infection risk by utilizing telemedicine would be useful in these instances. Telemedicine can help to reduce infection spread by limiting unnecessary in-person interactions and help conserve personal protective equipment (PPE) by facilitating remote care with the added benefits of expanding care to broad geographic areas, limiting cost, time, and travel burden on patients and families, and enabling consistent follow up.

The Effectiveness of Two Potential Mass Media Interventions on Stigma: Video-Recorded Social Contact and Audio/Visual Simulations.

Two approaches that may be particularly well suited for mass media (large scale) stigma interventions are video-recorded social contact and simulations, but research is rather limited. The purpose of this study was to evaluate two potential mass media interventions on different facets of stigma. Participants (N = 244) completed stigma measures prior to, immediately following, and 1 week following the random assignment of: (1) video-recorded social contact, (2) an audio/visual simulation, or (3) no intervention. The video-recorded social contact led to decreases on preference for social distance and negative emotions across 1 week, but only a temporary decrease on perceptions of dangerousness. In contrast, no significant changes in stigma were noted following the simulation. In sum, video-recorded social contact appears promising and offers many advantages for mass media implementation including low cost, minimal resources, and ease of dissemination. In contrast, further evaluation of audio/visual simulations is warranted before implementation.

Rapid In-Vitro Inactivation of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Using Povidone-Iodine Oral Antiseptic Rinse.

PURPOSE: To investigate the optimal contact time and concentration for viricidal activity of oral preparation of povidone-iodine (PVP-I) against SARS-CoV-2 ('corona virus') to mitigate the risk and transmission of the virus in the dental practice. MATERIALS AND METHODS: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) USA-WA1/2020 strain, virus stock was tested against oral antiseptic solutions consisting of aqueous povidone-iodine (PVP-I) as the sole active ingredient. The PVP-I was tested at diluted concentrations of 0.5%, 1%, and 1.5%. Test media without any virus was added to 2 tubes of the compounds to serve as toxicity and neutralization controls. Ethanol (70%) was tested in parallel as a positive control, and water only as a negative control. The test solutions and virus were incubated at room temperature (22 ± 2 °C) for time periods of 15 and 30 seconds. The solution was then neutralized by a 1/10 dilution in minimum essential medium (MEM) 2% fetal bovine serum (FBS), 50 µg/mL gentamicin. Surviving virus from each sample was quantified by standard end-point dilution assay and the log reduction value (LRV) of each compound compared to the negative (water) control was calculated. RESULTS: PVP-I oral antiseptics at all tested concentrations of 0.5%, 1%, and 1.5%, completely inactivated SARS-CoV-2 within 15 seconds of contact. The 70% ethanol control group was unable to completely inactivate SARS-CoV-2 after 15 seconds of contact, but was able to inactivate the virus at 30 seconds of contact. CONCLUSIONS: PVP-I oral antiseptic preparations rapidly inactivated SARS-CoV-2 virus in vitro. The viricidal activity was present at the lowest concentration of 0.5 % PVP-I and at the lowest contact time of 15 seconds. This important finding can justify the use of preprocedural oral rinsing with PVP-I (for patients and health care providers) may be useful as an adjunct to personal protective equipment, for dental and surgical specialties during the COVID-19 pandemic.

Comparison of In Vitro Inactivation of SARS CoV-2 with Hydrogen Peroxide and Povidone-Iodine Oral Antiseptic Rinses.

PURPOSE: To evaluate the in vitro inactivation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with hydrogen peroxide (H2 O2 ) and povidone-iodine (PVP-I) oral antiseptic rinses at clinically recommended concentrations and contact times. MATERIALS AND METHODS: SARS-CoV-2, USA-WA1/2020 strain virus stock was prepared prior to testing by growing in Vero 76 cells. The culture media for prepared virus stock was minimum essential medium (MEM) with 2% fetal bovine serum (FBS) and 50 µg/mL gentamicin. Test compounds consisting of PVP-I oral rinse solutions and H2 O2 aqueous solutions were mixed directly with the virus solution so that the final concentration was 50% of the test compound and 50% of the virus solution. Thus PVP-I was tested at concentrations of 0.5%, 1.25%, and 1.5%, and H2 O2 was tested at 3% and 1.5% concentrations to represent clinically recommended concentrations. Ethanol and water were evaluated in parallel as standard positive and negative controls. All samples were tested at contact periods of 15 seconds and 30 seconds. Surviving virus from each sample was then quantified by standard end-point dilution assay and the log reduction value of each compound compared to the negative control was calculated. RESULTS: After the 15-second and 30-second contact times, PVP-I oral antiseptic rinse at all 3 concentrations of 0.5%, 1.25%, and 1.5% completely inactivated SARS-CoV-2. The H2 O2 solutions at concentrations of 1.5% and 3.0% showed minimal viricidal activity after 15 seconds and 30 seconds of contact time. CONCLUSIONS: SARS-CoV-2 virus was completely inactivated by PVP-I oral antiseptic rinse in vitro, at the lowest concentration of 0.5 % and at the lowest contact time of 15 seconds. Hydrogen peroxide at the recommended oral rinse concentrations of 1.5% and 3.0% was minimally effective as a viricidal agent after contact times as long as 30 seconds. Therefore, preprocedural rinsing with diluted PVP-I in the range of 0.5% to 1.5% may be preferred over hydrogen peroxide during the COVID-19 pandemic.

Group 10 Bis(iminosemiquinone) Complexes: Measurement of Singlet-Triplet Gaps and Analysis of the Effects of Metal and Geometry on Electronic Structure.

Bis(iminosemiquinone) complexes of divalent group 10 metals have been described as having open-shell singlet ground states characteristic of very strong coupling between the two ligand radicals. By using the nonlinear temperature dependence of the chemical shifts of the 1H NMR spectra, the singlet-triplet gaps in seven of these compounds have been measured, with the nickel compounds having gaps of about 2400 cm-1 and the palladium compounds about 1800 cm-1. Bis(iminosemiquinone)platinum complexes have singlet-triplet gaps too large to measure by this technique (over 2800 cm-1, estimated to be about 3000 cm-1), though bis(3,5-di- tert-butylbenzosemiquinonato)platinum(II) has a measurable singlet-triplet gap of 1850 cm-1. In combination with near-IR absorption data of the neutral, cationic, and anionic bis(iminosemiquinone) complexes, a simplified two-electron, two-orbital bonding model describing these compounds can be fully parametrized based on experimental data. The identity of the central metal principally affects the difference in energy between metal-ligand π nonbonding and metal-ligand π antibonding orbitals, with the strength of the bonding interactions increasing in the order Pd < Ni < Pt. Twisting the ligands out of planarity (by using a 2,2'-biphenylenediyl linker) has a marked effect on the optical spectra of the compounds but not on their singlet-triplet gaps; this indicates that the effect is not due to changes in bonding interactions but rather due to a decrease in the magnitude of the quantum mechanical exchange interactions in the twisted compared to the flat compounds.

When Do Strongly Coupled Diradicals Show Strongly Coupled Reactivity? Thermodynamics and Kinetics of Hydrogen Atom Transfer Reactions of Palladium and Platinum Bis(iminosemiquinone) Complexes.

The 2,2'-biphenylene-bridged bis(iminosemiquinone) complexes ( tBuClip)M [ tBuClipH4 = 4,4'-di- tert-butyl- N, N'-bis(3,5-di- tert-butyl-2-hydroxyphenyl)-2,2'-diaminobiphenyl; M = Pd, Pt] can be reduced to the bis(aminophenoxide) complexes ( tBuClipH2)M by reaction with hydrazobenzene (M = Pd) or by catalytic hydrogenation (M = Pt). The palladium complex with one aminophenoxide ligand and one iminosemiquinone ligand, ( tBuClipH)Pd, is generated by comproportionation of ( tBuClip)Pd with ( tBuClipH2)Pd in a process that is both slow (0.06 M-1 s-1 in toluene at 23 °C) and only modestly favorable ( Kcom = 1.9 in CDCl3), indicating that both N-H bonds have essentially the same bond strength. The mono(iminoquinone) complex ( tBuClipH)Pt has not been observed, indicating that the platinum analogue shows no tendency to comproportionate ( Kcom < 0.1). The average bond dissociation free energies (BDFE) of the complexes have been established by equilibration with suitably substituted hydrazobenzenes, and the palladium bis(iminosemiquinone) is markedly more oxidizing than the platinum compound, with hydrogen transfer from ( tBuClipH2)Pt to ( tBuClip)Pd occurring with Δ G° = -8.9 kcal mol-1. The palladium complex ( tBuClipH2)Pd reacts with nitroxyl radicals in two observable steps, with the first hydrogen transfer taking place slightly faster than the second. In the platinum analogue, the first hydrogen transfer is much slower than the second, presumably because the N-H bond in the monoradical complex ( tBuClipH)Pt is unusually weak. Using driving force-rate correlations, it is estimated that this bond has a BDFE of 55.1 kcal mol-1, which is 7.1 kcal mol-1 weaker than that of the first N-H bond in ( tBuClipH2)Pt. The two radical centers in the platinum, but not the palladium, complex thus act in concert with each other and display a strong thermodynamic bias toward two-electron reactivity. The greater thermodynamic and kinetic coupling in the platinum complex is attributed to the stronger metal-ligand π interactions in this compound.

The Mediating Role of Self-Criticism in the Relationship between Parental Expressed Emotion and NSSI.

Nonsuicidal self-injury (NSSI) is found at high rates among adolescents and young adults and is associated with many negative consequences, warranting additional research. Two factors that may contribute to NSSI during this time period are one's levels of self-criticism and perceptions of their parental relationships; however, these relationships have received limited attention. The purpose of this current study was to address this gap in the literature. Adolescents and young adults (n=294) completed measures of perceived parental expressed emotion, self-criticism, and NSSI. Participants with a history of NSSI reported perceiving their parents as providing less emotional support, inducing more irritation, being more intrusive, and expressing more criticism compared to those without a history of NSSI. These individuals also endorsed greater self-criticism. Further, self-criticism mediated the relationship between perceived parental expressed emotion and NSSI occurrence, such that those with higher reported self-criticism and greater perceived parental expressed emotion were more likely to engage in NSSI.

The Metal or the Ligand? The Preferred Locus for Redox Changes in Oxygen Atom Transfer Reactions of Rhenium Amidodiphenoxides.

The rhenium(V) oxo complex oxo(triphenylphosphine) (bis(3,5-di-tert-butyl-2-phenoxo)amido)rhenium(V), (ONOCat)ReO(PPh3), reacts with molecular oxygen to give triphenylphosphine oxide and the dimeric rhenium(VII) complex fac,anti-(ONOCat)Re(O)(µ-O)2Re(O)(ONOCat). The ONO ligand adopts an unusual fac geometry, presumably to maximize π donation to rhenium; strong π donation is substantiated by the intraligand bond distances (metrical oxidation state = -2.24(9)). Addition of the N-heterocyclic carbene ligand IMes to fac,anti-(ONOCat)Re(O)(µ-O)2Re(O)(ONOCat) cleaves the dimer into monomeric C1-symmetric fac-(ONOCat)ReO2(IMes). The monorhenium(VII) complex is deoxygenated by PMe2Ph to give the rhenium(V) compound (ONOCat)ReO(IMes), which can be independently prepared by ligand substitution of (ONOCat)ReO(PPh3). The degree of stereochemical rigidity exhibited by the dioxo compound, as established by dynamic NMR spectroscopy, excludes the intermediacy of mer-(ONOQ)ReVO2(IMes) in this oxygen atom transfer reaction. Thus, oxygen atom transfer takes place preferentially by direct reduction of the oxorhenium(VII) moiety (classical oxygen atom transfer) rather than through initial internal electron transfer and ligand-centered reduction of an oxorhenium(V)-iminoquinone.

The Effects of Direct-To-Consumer-Advertising on Mental Illness Beliefs and Stigma.

Despite widespread use, little is known about how video direct-to-consumer-advertising (DTCA) influences beliefs about or stigma towards mental illness. The purpose of this study was to examine the effects of a medication advertisement on beliefs and stigma towards one mental disorder-bipolar disorder. A total of 424 participants were randomly assigned to view a medication or automobile advertisement and completed measures of beliefs and stigma towards bipolar disorder before and immediately after the advertisement. The medication advertisement did not lead to changes in perception of biological etiology, but did lead to increases in perception of prevalence, treatability, and controllability. No substantive changes were noted in stigma. In contrast to previous research and speculation, DTCA did not have an immediate, substantial impact on stigma or contribute to the "medicalization" of mental disorders.

Stigma towards Marijuana Users and Heroin Users.

Despite high levels of stigmatizing attitudes and behaviors toward individuals with substance use problems, there is surprisingly limited research on understanding the contributors to such high levels. College students with no history of marijuana or heroin use (N=250) completed self-report measures to examine the level of substance use stigma towards individuals using two illicit substances (marijuana and heroin) and the contribution of three perceiver characteristics (sex, previous contact with substance users, and five beliefs about substance use) to three dimensions of stigma (social distance, negative emotions, and forcing treatment). Greater levels of internalized stigma were noted towards individuals who use heroin (versus marijuana). For marijuana use, those who had less previous contact and higher endorsement of certain beliefs (rarity, severity, and less controllability) were associated with greater stigmatizing attitudes. For heroin use, the associations were weak or non-existent. The findings strengthen the argument that substance use stigma needs to be examined and perhaps addressed substance by substance, rather than as a group. Further, contact interventions may be a particularly effective strategy for altering substance use stigma.

Chromatin and epigenetic regulation of pre-mRNA processing.

New data are revealing a complex landscape of gene regulation shaped by chromatin states that extend into the bodies of transcribed genes and associate with distinct RNA elements such as exons, introns and polyadenylation sites. Exons are characterized by increased levels of nucleosome positioning, DNA methylation and certain histone modifications. As pre-mRNA splicing occurs co-transcriptionally, changes in the transcription elongation rate or epigenetic marks can influence exon splicing. These new discoveries broaden our understanding of the epigenetic code and ascribe a novel role for chromatin in controlling pre-mRNA processing. In this review, we summarize the recently discovered interplay between the modulation of chromatin states and pre-mRNA processing with the particular focus on how these processes communicate with one another to control gene expression.

Mechanism and selectivity of methyl and phenyl migrations in hypervalent silylated iminoquinones.

Chlorosilanes R(X)(Y)SiCl (R = Me, Ph; X, Y = Me, Ph, Cl) have been reported to react with Pb(ONO(Q))2 (ONO(Q) = 3,5-di-tert-butyl-1,2-quinone-(3,5-di-tert-butyl-2-oxy-1-phenyl)imine) to give five-coordinate (X)(Y)Si(ON[R]O), in which the R group has migrated from silicon to nitrogen. This migration is intramolecular, as confirmed by the lack of crossover between (CH3)3SiCl and (CD3)3SiCl in their reaction with Pb(ONO(Q))2. Reaction of PhSiMeCl2 takes place with high kinetic stereoselectivity to produce isomer Ph(Cl)Si(ON[Me]O) in which the phenyl is axial in the trigonal bipyramid, which subsequently isomerizes to the thermodynamic isomer with axial chlorine. This indicates that migration takes place preferentially from the stereoisomer of the octahedral intermediate, κ(3)-Ph(CH3)(Cl)Si(ONO(Q)), in which the phenyl and methyl groups are mutually trans, indicating that the observed complete selectivity for methyl over phenyl migration is due to intrinsic differences in migratory aptitude. DFT calculations suggest that migration takes place from this isomer not because it undergoes migration faster than other possible stereoisomers, but because it is formed most rapidly, and migration occurs faster than isomerization.

Metal and ligand effects on bonding in group 6 complexes of redox-active amidodiphenoxides.

Group 6 complexes M(ONO)2 (M = Cr, Mo, W; ONO = bis(2-oxy-3,5-di-tert-butylphenyl)amide) are prepared by the reaction of divalent metal halide precursors with Pb(ONO(Q))2. Analogous complexes containing the 2,4,6,8-tetra-tert-butyl-1,9-dioxophenoxazinate ligand (DOPO) are prepared by protonolysis of chromocene with H(DOPO(Q)) or by reaction of Pb(DOPO(Q))2 with M2Br4(CO)8 (M = Mo, W). The molybdenum and tungsten complexes are symmetrical, octahedral compounds for which spectroscopic data are consistent with M(VI) complexes with fully reduced [L(Cat)](3-) ligands. Quantitative analysis of the intraligand bond lengths, by comparison with literature standards, allows calculation of metrical oxidation states (MOS) for the ONO ligands. The MOS values of the tungsten and molybdenum complexes indicate that π donation from the ligand is weak and that differences between the ONO and DOPO ligands are small. In both the solid state and in solution, Cr(DOPO)2 is paramagnetic with localized quinone and semiquinone ligands bound to Cr(III). The geometry and electronic structure of Cr(ONO)2 differ in the solid state and in solution, as determined by crystallography, magnetic measurements, and Cr K-edge X-ray absorption spectroscopy. In solution, the structure resembles that of the DOPO analogue. In contrast, solid Cr(ONO)2 is a singlet, and X-ray absorption near-edge spectroscopy indicates that the chromium is significantly more oxidized in the solid state than in solution. An electronic description compounds to that of the tungsten and molybdenum analogues, but with considerably more charge transfer from the ligand to chromium via π donation, is in agreement with the experimental observations.

Patellotibial contusions: a rare cruciate ligament injury pattern.

OBJECTIVE: Patellotibial contusions are a recently described contusion pattern in anterior cruciate ligament (ACL) tears. The purposes or our study were to determine if patellotibial contusions are specific to ACL injuries, determine the internal derangements in patients demonstrating this contusion, and suggest a mechanism of injury. MATERIALS AND METHODS: We conducted a retrospective search of radiology reports over a 6-year period to identify patients with patellar edema described on magnetic resonance (MR) imaging. Only individuals with patellar and tibial edema were included in the study group. These MR examinations were then reviewed for associated internal derangements. RESULTS: From March 2007 to June 2013, 1914 MR examinations of the knee were performed. Two hundred seventy-one reports described patellar edema. Seven individuals had edema of both the inferior pole of the patella and the anterior tibial plateau. Three individuals were involved in motor vehicle accidents (MVAs); 4 patients had a history of an axial load or sports-related injury. All 3 patients involved in MVAs had posterior cruciate ligament tears consistent with posterior translation of the tibia. The non-MVA individuals had tears of the ACL with internal derangements similar to other ACL deficient knees, however, with more widespread osseous contusions. CONCLUSIONS: Patellotibial contusions are high-energy injuries resulting in cruciate ligament tears. These contusions occur exclusively in patients with ACL tears when individuals with a history of direct impaction to the knee are excluded. Axial loading of the extended knee may be an important mechanism of injury in these individuals.

Stress injury of the rib in a swimmer.

Rib stress injuries are uncommonly reported but have been documented among athletes, most notably rowers. There have only been two prior case reports of rib stress injuries in swimmers, both of which were young females. Magnetic resonance (MR) imaging was either not obtained or the imaging characteristics were incompletely described. We present a case of an isolated third rib stress injury in a collegiate male swimmer diagnosed via MR imaging. We briefly discuss the possible etiologies for rib stress injuries, their MR appearance, as well as their treatment.

Markov decision process design: A framework for integrating strategic and operational decisions.

We consider the problem of optimally designing a system for repeated use under uncertainty. We develop a modeling framework that integrates the design and operational phases, which are represented by a mixed-integer program and discounted-cost infinite-horizon Markov decision processes, respectively. We seek to simultaneously minimize the design costs and the subsequent expected operational costs. This problem setting arises naturally in several application areas, as we illustrate through examples. We derive a bilevel mixed-integer linear programming formulation for the problem and perform a computational study to demonstrate that realistic instances can be solved numerically.