Using implementation science to decrease variation and high opioid administration in a surgical ICU

BACKGROUND

High doses and prolonged duration of opioids are associated with tolerance, dependence, and increased mortality. Unfortunately, despite recent efforts to curb outpatient opioid prescribing because of the ongoing epidemic, utilization remains high in the intensive care setting, with intubated patients commonly receiving infusions with a potency much higher than doses required to achieve pain control. We attempted to use implementation science techniques to monitor and reduce excessive opioid prescribing in ventilated patients in our Surgical ICU.

METHODS

We conducted a prospective study investigating opioid administration in a closed SICU at an academic medical center over 18 months. Commonly accepted conversions were used to aggregate daily patient opioid use. Patients with a history of chronic opioid use and those being treated with an ICP monitor/drain, neuromuscular blocker, or ECMO were excluded. If the patient spent a portion of a day on a ventilator, that day's total was included in the "vent group." MMEs per patient were collected for each patient and assigned to the on-call intensivist. Intensivists were blinded to the data for the first seven months. They were then provided with academic detailing followed by audit & feedback over the subsequent 11 months, demonstrating how opioid utilization during their time in the SICU compared to the unit average and a blinded list of the other attendings. Student's T-tests were performed to compare opioid utilization before and after initiation of academic detailing and audit & feedback.

RESULTS

Opioid utilization in patients on a ventilator decreased by 20.1% during the feedback period, including less variation among all intensivists and a 30.9% reduction by the highest prescribers.

CONCLUSION

Implementation science approaches can effectively reduce variation in opioid prescribing, especially for high outliers in a SICU. These interventions may reduce the risks associated with prolonged use of high-dose opioids.

LEVEL OF EVIDENCE

Prospective pre-post-intervention, Level II.

Impact of Pendent Ammonium Groups on Solubility and Cycling Charge Carrier Performance in Nonaqueous Redox Flow Batteries

The synthesis, characterization, electrochemical performance, and theoretical modeling of two base-metal charge carrier complexes incorporating a pendent quaternary ammonium group, [Ni(bppn-Me3)][BF4], 3', and [Fe(PyTRENMe)][OTf]3, 4', are described. Both complexes were produced in high yield and fully characterized using NMR, IR, and UV-vis spectroscopies as well as elemental analysis and single-crystal X-ray crystallography. The solubility of 3' in acetonitrile showed a 283% improvement over its neutral precursor, whereas the solubility of complex 4' was effectively unchanged. Cyclic voltammetry indicates an ∼0.1 V positive shift for all waves, with some changes in reversibility depending on the wave. Bulk electrochemical cycling demonstrates that both 3' and 4' can utilize the second more negative wave to a degree, whereas 4' ceases to have a reversible positive wave. Flow cell testing of 3' and 4' with Fc as the posolyte reveals little improvement to the cycling performance of 3' compared with its parent complex, whereas 4' exhibits reductions in capacity decay when cycling either negative wave. Postcycling CVs indicate that crossover is the likely source of capacity loss in complexes 3, 3', and 4' because there is little change in the CV trace. Density functional theory calculations indicate that the ammonium group lowers the HOMO energy in 3' and 4', which may impart stability to cycling negative waves while making positive waves less accessible. Overall, the incorporation of a positively charged species can improve solubility, stored electron density, and capacity decay depending on the complex, features critical to high energy density redox flow battery performance.

Hydrazine Energy Storage: Displacing N2 H4 from the Metal Coordination Sphere

Hydrogen carriers, such as hydrazine (N₂ H₄ ), may facilitate long duration energy storage, a vital component for resilient grids by enabling more renewable energy generation. Lanthanide coordination chemistry with N₂ H₄ as well as efforts to displace N₂ H₄ from the metal coordination sphere to develop an efficient catalytic production cycle were detailed. Modeling the equilibrium of different ligand coordination, it was predicted that strong sigma donor molecules would be required to displace N₂ H₄ . Monitoring competition experiments with nuclear magnetic resonance confirmed that trimethyl phosphine oxide, dimethylformamide, and dimethyl sulfoxide displaced N₂ H₄ in large or small lanthanide complexes.

Simple model of arch support: Relevance to Charcot Neuroarthropathy

BACKGROUND

Charcot neuropathy is a common complication resulting from poorly controlled diabetes and peripheral neuropathy leading to the collapse, and ultimately the breakdown, of the midfoot. Mechanically, it is likely that a compromised arch support in this, or any other patient group that experiences foot flattening, would be associated with slippage at the distal and proximal interface regions of the plantar surface of the foot and the adjacent support surface. This slippage, although difficult to quantify with standard motion capture systems used in a gait laboratory, could potentially be assessed with systems for monitoring interface shear stresses. However, before investing in such systems, a correlation between arch flattening and interface shear stresses needs to be verified.

METHODS

For this purpose, a sagittal plane model of a foot was developed using a multi-body dynamics package (MSC Adams). This model mimicked a subject swaying back and forth, and was constructed to show the dependence of interface stresses on altered arch support.

FINDINGS

The model's predictions matched typical FootSTEPS data: lengthening of the arch of 1-2 mm, sway oscillations of 0.22-0.33 s and frictional force differences (calcaneus relative to forefoot) of 60 N. Of clinical relevance, when the stiffness of the plantar spring (representing aponeurosis and intrinsic muscles) was reduced by 10%, the frictional force difference increased by about 6.5%.

INTERPRETATION

The clinical implications of this study are that, while arch lengthening of less than 2 mm might be difficult to measure reliably in a gait lab, using shear sensors under the forefoot and hindfoot should allow arch support to be assessed in a repeatable manner.

A Comparative Review of Metal-Based Charge Carriers in Nonaqueous Flow Batteries

Invited for this month's cover is the joint redox flow battery team from Sandia and Los Alamos National Laboratories. The cover image shows the stylized components of a redox flow battery (RFB) in the foreground, with renewable sources of energy generation in the background. The Review itself is available at 10.1002/cssc.202002354.

A Comparative Review of Metal-Based Charge Carriers in Nonaqueous Flow Batteries

Energy storage is becoming the chief barrier to the utilization of more renewable energy sources on the grid. With independent service operators aiming to acquire gigawatts in the next 10-20 years, there is a large need to develop a suite of new storage technologies. Redox flow batteries (RFB) may be part of the solution if certain key barriers are overcome. This Review focuses on a particular kind of RFB based on nonaqueous media that promises to meet the challenge through higher voltages than the organic and aqueous variants. This class of RFB is divided into three groups: molecular, macromolecular, and redox-targeted systems. The growing field of theoretical modeling is also reviewed and discussed.

ROTEM as a Predictor of Mortality in Patients With Severe Trauma

BACKGROUND

Hemorrhage, especially when complicated by coagulopathy, is the most preventable cause of death in trauma patients. We hypothesized that assessing hemostatic function using rotational thromboelastometry (ROTEM) or conventional coagulation tests can predict the risk of mortality in patients with severe trauma indicated by an injury severity score greater than 15.

METHODS

We retrospectively reviewed trauma patients with an injury severity score >15 who were admitted to the emergency department between November 2015 and August 2017 in a single level I trauma center. Patients with available ROTEM and conventional coagulation data (partial thromboplastin time [PTT], prothrombin time [PT], and international normalized ratio) were included in the study cohort. Logistic regression was performed to assess the relationship between coagulation status and mortality.

RESULTS

The study cohort included 301 patients with an average age of 47 y, and 75% of the patients were males. Mortality was 23% (n = 68). Significant predictors of mortality included abnormal APTEM (thromboelastometry (TEM) assay in which fibrinolysis is inhibited by aprotinin (AP) in the reagent) parameters, specifically a low APTEM alpha angle, a high APTEM clot formation time, and a high APTEM clotting time. In addition, an abnormal international normalized ratio significantly predicted mortality, whereas abnormal PT and PTT did not.

CONCLUSIONS

A low APTEM alpha angle, an elevated APTEM clot formation time, and a high APTEM clotting time significantly predicted mortality, whereas abnormal PT and PTT did not appear to be associated with increased mortality in this patient population. Viscoelastic testing such as ROTEM appears to have indications in the management and stabilization of trauma patients.

Linked Picolinamide Nickel Complexes as Redox Carriers for Nonaqueous Flow Batteries

The use of nickel complexes utilizing non-innocent ligands based on picolinamide to function as redox carriers in flow batteries was explored. The picolinamide moiety was linked together with -CH₂ CH₂ - (bpen), -CH₂ CH₂ CH₂ - (bppn), and -C₆ H₄ - (bpb) moieties, resulting in two, three, and four quasi-reversible waves, respectively, for the nickel complexes and >3 V difference between the outermost positive and negative waves. The redox events were theoretically modelled for each complex, showing excellent agreement (<0.3 V difference) between the experimental and modelled potentials. Bulk cycling of the most soluble complex, Ni(bppn), indicated only one of the three waves was reversible. Therefore, Ni(bppn) has the ability to act as a negative charge redox carrier in flow cells.

Impact of Ligand Substitutions on Multielectron Redox Properties of Fe Complexes Supported by Nitrogenous Chelates

Redox flow batteries (RFBs) have recently been recognized as a potentially viable technology for scalable energy storage. To take full advantage of RFBs, one possible approach for achieving high energy densities is to maximize a number of redox events by utilizing charge carriers capable of multiple one-electron transfers within the electrochemical window of solvent. However, past efforts to develop more efficient electrolytes for nonaqueous RFBs have mostly been empirical. In this manuscript, we shed light on design principles by theoretically investigating the effects of systematically substituting pyridyl moieties with imine ligands within a series of Fe complexes with some experimental validation. We found that such replacement is an effective strategy for reducing the molecular weight-to-charge ratios of these complexes. Simultaneously, calculations suggest that the reduction potentials and ligand-based redox activity of such substituted N-heterocyclic Fe compounds might be maintained within their +4 → -1 charge states. Additionally, by theoretically examining the role of coordination geometry, vis-à-vis reducing the number of redox noninnocent ligands within the first coordination sphere, we have demonstrated that Fe complexes with one such ligand were also capable of supporting multielectron reduction events and exhibited reduction potentials similar to their parent analogs supported by two or three of the same multidentate ligands. However, some differences in redox nature within the lower (+2 → -1) charge states were also noticed. Specifically, complexes containing two bidentate ligands, or one tridentate ligand, exhibited ligand-based reductions, whereas compounds with one bidentate ligand exhibited metal-centered reductions. The current results pave the way toward the design of the next-generation of Fe complexes with lower molecular weights and greater stored energy for redox flow batteries.

Efficacy of the Abdominal Aortic Junctional Tourniquet-Torso Plate in a Lethal Model of Noncompressible Torso Hemorrhage

BACKGROUND

The Abdominal Aortic Junctional Tourniquet, when modified with an off-label, prototype, accessory pressure distribution plate (AAJT-TP), has the potential to control noncompressible torso hemorrhage in prolonged field care.

METHODS

Using a lethal, noncompressible torso hemorrhage model, 24 male Yorkshire swine (81kg-96kg) were randomly assigned into two groups (control or AAJT-TP). Anesthetized animals were instrumented and an 80% laparoscopic, left-side liver lobe transection was performed. At 10 minutes, the AAJT-TP was applied and inflated to an intraabdominal pressure of 40mmHg. At 20 minutes after application, the AAJT-TP was deflated, but the windlass was left tightened. Animals were observed for a prehospital time of 60 minutes. Animals then underwent damage control surgery at 180 minutes, followed by an intensive care unit-phase of care for an additional 240 minutes. Survival was the primary end point.

RESULTS

Compared with Hextend, survival was not significantly different in the AAJT-TP group (ρ = .564), nor was blood loss (3.3L ± 0.5L and 3.0L ± 0.5L, respectively; p = .285). There was also no difference in all physiologic parameters between groups at the end of the study or end of the prehospital phase. Three of 12 AAJT-TP animals had an inferior vena cava thrombus.

CONCLUSION

The AAJT-TP did not provide any survival benefit compared with Hextend alone in this model of noncompressible torso hemorrhage.

Physical, structural, and dehydrogenation properties of ammonia borane in ionic liquids

Hydrogen desorption profiles of AB–ILs with H₂ yield.

Phasic behavior of EMG signals during gait: Use of multivariate statistics

The present study represents an attempt to ascertain whether there are some underlying trends that, in some combination, can explain all the variations in the linear envelopes of 16 EMG signals of selected leg muscles. Two kinds of analyses were performed: (a) a factor analysis of EMG data corresponding to 16 muscles of the lower limb and (b) a "multi-dimensional scaling" (MDS) procedure. The latter technique involved mapping the Cartesian coordinates for 16 points subject to the constraint that the distance between any two points reflected the degree of coactivity for the corresponding muscles. The results of these analyses showed that four factors could account for 91.5% of the variance in the original data set. These factors could be clearly demarcated on the "muscle map," tending to support the notion that there are motor "programs" for groups of muscles that have to perform a given function during locomotion. Further analysis of the loading matrix (i.e., correlations between each EMG vector and each of the four factors) showed groups of muscles that acted in a similar manner. The muscle groups could be divided into those that act at the times of (a) heelstrike, (b) single limb loading response, (c) propulsion phase, or else (d) acted in a biphasic manner.

The physiological and behavioral response of pigs castrated with and without anesthesia or analgesia

Surgical castration is a common management practice performed on male pigs to prevent the occurrence of boar taint. Surgical castration is known to cause physiological and behavioral changes in pigs indicative of pain-induced distress; however, it is commonly performed without pain relief. The objective of this study was to evaluate the effectiveness of carbon dioxide gas (CO(2)) anesthesia and a non-steroidal anti-inflammatory drug (NSAID) to alleviate the pain caused by castration. At 3 d of age, male pigs were either control handled (CON), castrated without pain relief (CAS), given an NSAID and then immediately castrated (CAS+NSAID), anesthetized with CO(2) and then castrated (CAS+CO2), or anesthetized with CO(2) and given an NSAID at the time of castration (CAS+BOTH). Blood samples were collected before castration, and at 30, 60, 120, and 180 min, 24 h, and 3 d after castration or handling for analysis of cortisol, C-Reactive protein (CRP), and substance-P (SP) concentrations. This study was then repeated using the same treatment groups, and the behavioral response to castration and handling were measured using a 1-min scan sampling procedure. The percentage of stress vocalizations was recorded during the administration of all treatments. Anesthesia and analgesia did not effectively reduce (P > 0.05) the cortisol response to surgical castration. Overall, CRP concentrations were greater (P < 0.05) in CAS+CO2 pigs as compared with CON pigs. Sixty minutes after castration or handling, SP concentrations were greater (P < 0.08) in pigs given CO(2) anesthesia (CO2, CAS+CO2, and CAS+BOTH) than CON, CAS, and CAS+NSAID pigs. Pigs castrated without pain relief spent more (P < 0.001) time lying without contact than all other treatments during the first 30 min after castration, but thereafter CAS+CO2 pigs spent more (P < 0.001) time lying without contact than other treatments. During the first 30 min after the treatments were applied, CAS+CO2 pigs spent more (P < 0.01) time displaying pain-like behaviors than CON, CAS, CAS+NSAID, and CAS+BOTH pigs. The percentage of stress vocalizations was greater (P < 0.05) in CAS and CAS+NSAID pigs than all other treatments. Neither CO(2) anesthesia nor a NSAID, given separately or combined, markedly reduced the pain-induced distress caused by castration in pigs. More research is needed to evaluate practical methods of on-farm pain relief for pigs.

A haptic unit designed for magnetic-resonance-guided biopsy

The magnetic fields present in the magnetic resonance (MR) environment impose severe constraints on any mechatronic device present in its midst, requiring alternative actuators, sensors, and materials to those conventionally used in traditional system engineering. In addition the spatial constraints of closed-bore scanners require a physical separation between the radiologist and the imaged region of the patient. This configuration produces a loss of the sense of touch from the target anatomy for the clinician, which often provides useful information. To recover the force feedback from the tissue, an MR-compatible haptic unit, designed to be integrated with a five-degrees-of-freedom mechatronic system for MR-guided prostate biopsy, has been developed which incorporates position control and force feedback to the operator. The haptic unit is designed to be located inside the scanner isocentre with the master console in the control room. MR compatibility of the device has been demonstrated, showing a negligible degradation of the signal-to-noise ratio and virtually no geometric distortion. By combining information from the position encoder and force sensor, tissue stiffness measurement along the needle trajectory is demonstrated in a lamb liver to aid diagnosis of suspected cancerous tissue.

Space requirements of weaned pigs during a sixty-minute transport in summer

Currently, there are no trucking quality assurance recommendations for space allowance of weaned pigs during transport in the United States. The objective of this research was to establish a first estimate of the space requirements of weaned pigs during transport in summer based on measures of animal well-being. A commercial semi-trailer was fitted with compartments that provided 0.05, 0.06, and 0.07 m(2)/pig, which were replicated on the upper and lower deck, with a constant 100 pigs per compartment. Cameras were placed in each experimental compartment to record behaviors and postures of pigs during transport. The frequencies of standing, lying, sitting, standing/rearing on another pig, and lying/huddling on top of another pig were recorded using 1-min scan samples during the entire duration of transport. Blood samples were collected and BW and lesion scores recorded from 32 pigs per space allowance for physiological and immune measures before and after transport (n = 32 pigs/treatment). Pigs were transported for 60 +/- 5 min to the wean-to-finishing site using the same route for each replicate during summer (temperature: 28.4 +/- 1.2 degrees C and relative humidity: 59.8 +/- 4.4% within the trailer). Data were analyzed using the MIXED procedure (SAS Institute Inc., Cary, NC). Cortisol, hematocrit, blood urea nitrogen, total protein, albumin, aspartate aminotransferase, creatine kinase, and gamma-glutamyl transferase increased (P < 0.05) after transport regardless of space allowance. Plasma glucose and BW decreased (P < 0.05) after transport regardless of space allowance. Lesion scores increased (P < 0.001) after transport and were greater (P < 0.05) for barrows compared with gilts. The neutrophil to lymphocyte ratio was greater (P < 0.005) for pigs transported at 0.05 m(2)/pig compared with pigs transported at 0.06 and 0.07 m(2)/pig. Pigs transported at 0.05 m(2)/pig lay down less (P < 0.05) than pigs transported at 0.06 and 0.07 m(2)/pig between 30 and 60 min of transport. Greater neutrophil to lymphocyte ratio and less lying behavior performed by pigs transported at 0.05 m(2)/pig suggest that a minimum space allowance of 0.06 m(2)/pig was preferable when transporting weaned pigs for 60 min during summer in this study.

Effects of feeding Salmonella enterica serovar Typhimurium or serovar Choleraesuis on growth performance and circulating insulin-like growth factor-I, tumor necrosis factor-α, and interleukin-1β in weaned pigs1

The most common Salmonella serovars causing clinical disease in pigs are Salmonella enterica serovars Typhimurium (Typhimurium) and Choleraesuis. Given that the swine host-adapted serovar Choleraesuis has been reported to cause systemic disease, a different disease outcome from that of Typhimurium, our working hypothesis was that this serovar would likely engage systemic immune-inflammatory mechanisms, resulting in elevated systemic cytokine secretion. Forty-eight weaned pigs were blocked by BW and sex, and randomly allotted to 1 of 3 treatments in a 14-d study. Each treatment had 8 replicates (pens), with 2 pigs/pen. The treatments consisted of a negative control and pigs repeatedly fed 10(8) cfu of Typhimurium or Choleraesuis. On d 0, the pigs were fed Choleraesuis or Typhimurium in dough balls, and the bacteria were refed twice weekly throughout the experiment. Control pigs received dough balls without bacteria. All pigs were housed in temperature-controlled rooms under constant lighting and were fed a standard corn-soybean meal-based nursery diet. Pig BW and feed disappearance were used to determine ADG, ADFI, and G:F. Rectal temperatures were obtained daily from 1 pig/pen beginning 2 d before the first bacterial feeding through d 7 using rapid-response digital thermometers. Serum was collected on d 0, 7, and 14 from a single pig/pen for analysis of IGF-I, tumor necrosis factor-alpha , and IL-1beta. There was no change in the rectal temperature of the control or the Typhimurium-challenged pigs (compared with d 0) or when comparing Typhimurium-challenged pigs with control animals. In contrast, pigs fed Choleraesuis had increased rectal temperatures beginning on d 2 and continuing through d 7 (P < 0.05), with the greatest elevation on d 3 (P < 0.001) compared with the control pigs. Average daily gain and ADFI of pigs challenged with Typhimurium did not differ from those of the control animals. Pigs fed Choleraesuis had a 25% reduction in ADG (P < 0.0001) and ADFI (P < 0.002) compared with the control pigs. On d 7, pigs fed Choleraesuis had reduced serum IGF-I compared with control (P < 0.01) or Typhimurium-challenged pigs (P = 0.01). Bacterial feeding did not affect serum tumor necrosis factor-alpha or IL-1beta compared with control pigs at any time throughout the experiment. We conclude that repeated exposure of weaned pigs to Choleraesuis reduced growth performance in the absence of changes in systemic inflammatory cytokines.

C-H bond activation through steric crowding of normally inert ligands in the sterically crowded gadolinium and yttrium (C5Me5)3M complexes

Synthesis of the sterically crowded Tris(pentamethylcyclopentadienyl) lanthanide complexes, (C5Me5)3Ln, has demonstrated that organometallic complexes with unconventionally long metal ligand bond lengths can be isolated that provide options to develop new types of ligand reactivity based on steric crowding. Previously, the (C5Me5)3M complexes were known only with the larger lanthanides, La-Sm. The synthesis of even more crowded complexes of the smaller metals Gd and Y is reported here. These complexes allow an evaluation of the size/reactivity correlations previously limited to the larger metals and demonstrate a previously undescribed type of C5Me5-based reaction, namely C-H bond activation. (C5Me5)3Gd, was prepared from GdCl3 through (C5Me5)2GdCl2K(THF)2, (C5Me5)2Gd(C3H5), and [(C5Me5)2Gd][BPh4] and structurally characterized by x-ray crystallography. Although Gd3+ is redox-inactive, (C5Me5)3Gd functions as a reducing agent in reactions with 1,3,5,7-cyclooctatetraene (COT) and triphenylphosphine selenide to make (C5Me5)Gd(C8H8), [(C5Me5)2Gd]2Se2, and [(C5Me5)2Gd]2Se depending on the stoichiometry used. When the analogous synthetic method was attempted with yttrium in arene solvents, the previously characterized (C5Me5)2YR complexes (R=C6H5, CH2C6H5) were isolated instead, i.e., C-H bond activation of solvent occurred. To avoid this problem, (C5Me5)3Y was synthesized in high yield from [(C5Me5)2YH]2 and tetramethylfulvene in aliphatic solvents. Isolated (C5Me5)3Y was found to metalate benzene and toluene with concomitant formation of C5Me5H, a reaction contrary to the normal pKa values of these hydrocarbons. In this case, the normally inert (C5Me5)1- ligand engages in C-H bond activation due to the extreme steric crowding.

Photoluminescence Properties of Conjugated Phenylacetylene Monodendrons in Thin Films

We report the absorption, photoluminescence (PL), and time-dependent PL of thin films of conjugated phenylacetylene monodendrons at both room temperature and at cryogenic temperature. We find that the PL properties of the monodendron thin films are significantly different from their fluorescence in dilute solution due to the presence of interactions between monodendrons in the thin film. These interactions lead to aggregate species in the thin films, which result in broader PL spectra and lower PL quantum yields than for monodendrons in dilute solution. Evidence for excimer-like aggregates in the monodendron thin films is found from time-resolved PL spectra.

Optical and photophysical properties of light-harvesting phenylacetylene monodendrons based on unsymmetrical branching

The optical and photophysical properties of phenylacetylene dendritic macromolecules based on unsymmetrical branching are investigated using steady-state and time-dependent spectroscopy. Monodendrons, up to the fourth generation, are characterized with and without a fluorescent perylene trap at the core. The higher generation monodendrons without the perylene trap exhibit high molar extinction coefficients (>10(5) M(-1) cm(-1)) and high fluorescence quantum yields (65-81%). When a perylene trap is placed at the core, then the monodendrons typically exhibit high energy transfer quantum yields (approximately 90%), as well as subpicosecond time scale excited-state dynamics, as evidenced by ultrafast pump-probe measurements. The photophysical properties of the unsymmetrical monodendrons are compared to those of phenylacetylene monodendrons with symmetrical branching, which have been described recently. The high fluorescence quantum yields and large energy transfer quantum efficiencies exhibited by the unsymmetrical monodendrons suggest they have potential for applications in molecular-based photonics devices.

Urban stress and mental health among African-American youth: assessing the link between exposure to violence, problem behavior, and coping strategies

This project examines gender differences in exposure to violence, coping strategies and problem behavior among 306 African-American middle and high school students in the state of Virginia. Gender differences in problem behaviors among youth exposed to violence as either victims or witnesses are examined in addition to variations in coping strategies. Relying on recent research examining violent behavior and victimization events, the study focuses on the internalizing and externalizing behavioral characteristics (i.e., academic achievement, anxiety, depression, negative self-esteem, and delinquency) of urban students exposed to violence and the extent to which coping strategies differ. Results show specific gender differences with regard to problem behavior and coping strategy among African-American youth exposed to violence. For adolescent males, exposure to violence and victimization is strongly associated with externalizing problem behaviors such as delinquency, while adolescent females exposed to violence and victimization are more likely to exhibit internalizing symptoms indicative of post-traumatic stress disorder. Among students exposed to violence and victimization, females are more likely to use problem-focused coping (i.e., social support) as an adaptive strategy in comparison to males. Implications for intervention and future research are discussed.

Synthesis and structure of tris(alkyl- and silyl-tetramethylcyclopentadienyl) complexes of lanthanum

In efforts to make sterically crowded tris(peralkylcyclopentadienyl) complexes of lanthanum for the exploration of sterically induced reduction chemistry with a diamagnetic system, the synthesis of (C(5)Me(4)R)(3)La complexes has been pursued with R = Me, Et, (i)Pr, and SiMe(3). The complexes were synthesized in four steps: reaction of LaCl(3) with KC(5)Me(4)R to form (C(5)Me(4)R)(2)LaCl(2)K(THF)(2), addition of allylmagnesium chloride to make (C(5)Me(4)R)(2)La(C(3)H(5)), protonolysis with Et(3)NHBPh(4) to make [(C(5)Me(4)R)(2)La][BPh(4)], and finally the replacement of BPh(4)(-) with C(5)Me(4)R(-) using KC(5)Me(4)R to make (C(5)Me(4)R)(3)La. X-ray crystallographic data were obtainable on the (C(5)Me(4)R)(3)La complexes for R = Me, Et, (i)Pr, and SiMe(3). In each complex, the three C(5)Me(4)R ring centroids define a trigonal planar geometry around La. The average La-(ring centroid) distances are 2.64, 2.65, 2.66, and 2.69 A for the Me, Et, (i)Pr, and SiMe(3) structures, respectively, with La-C distances ranging from 2.857 (3) to 3.029 (2) A. Despite the steric crowding, ligand exchange can be observed by NMR spectroscopy.

Resonance Raman spectroscopy of mass selected Al2 in an argon matrix

In an excitation range of 620-760 nm, resonance Raman spectra of aluminum dimers (Al2) in an argon matrix have been obtained for the first time. Temperature annealing experiments were performed to remove Raman lines attributed site effects caused by the Al2/Ar matrix. We observe a single fundamental at 293.3 (5) cm(-1) along with a progression up to 1149 (1) cm(-1). Taking successive differences of band centers we obtain spectroscopic constants for the ground state fundamental, w(e) = 297.5 (5) cm(-1), the anharmonicity, e(e)x(e) = 1.68 (8) cm(-1). Our results are in close agreement with previous experimental results for Al2 which designate the ground state as a 3piu state, and may be considered as confirmation of this assignment.

Motor mechanisms in speech ontogeny: phylogenetic, neurobiological and linguistic implications

The rhythmic mandible-generated close-open alternations of the mouth, responsible for the series of consonant-vowel alternations characteristic of babbling and of languages, is receiving increased attention as a possible manifestation of an ontogenetic and phylogenetic 'frame' underlying the serial organization of speech. The supplementary motor area appears important for production of this consonant-vowel frame in adults.

Community health indicators predicting adolescent academic achievement

Throughout the literature investigating adolescent academic achievement, little or no attention has been focused on indicators of community health as factors that share variance with academic achievement. The purpose of this study was to conduct exploratory analyses using indicators of community health to investigate adolescent academic achievement. This study employed hierarchical linear multiple regression to explain variations in adolescent academic achievement as measured by standardized tests for two different school years. The unit of analyses was the school district with the standardized test results of 8th grade students as academic achievement. The first model of the school district for school year 1997-98 accounted for almost 58% of the variance in adolescent academic achievement. This model was replicated on a different school year and it accounted for almost 63% of the variance in adolescent academic achievement. These strong models hold great promise for future investigations of adolescent academic achievement using indicators of community health and other community contextual variables.

An extensometer for global measurement of bone strain suitable for use in vivo in humans

An axial extensometer able to measure global bone strain magnitudes and rates encountered during physiological activity, and suitable for use in vivo in human subjects, is described. The extensometer uses paired capacitive sensors mounted to intraosseus pins and allows measurement of strain due to bending in the plane of the extensometer as well as uniaxial compression or tension. Data are presented for validation of the device against a surface-mounted strain gage in an acrylic specimen under dynamic four-point bending, with square wave and sinusoidal loading inputs up to 1500 mu epsilon and 20 Hz, representative of physiological strain magnitudes and frequencies. Pearson's correlation coefficient (r) between extensometer and strain gage ranged from 0.960 to 0.999. Mean differences between extensometer and strain gage ranged up to 15.3 mu epsilon. Errors in the extensometer output were directly proportional to the degree of bending that occurs in the specimen, however, these errors were predictable and less than 1 mu epsilon for the loading regime studied. The device is capable of tracking strain rates in excess of 90,000 mu epsilon/s.

Quantifying muscle activity in non-ambulatory children with spastic cerebral palsy before and after selective dorsal rhizotomy

Cerebral palsy is a condition that results in varying degrees of functional deficits. The goal of this study was to develop an objective measure of muscle activity during a prescribed voluntary motor task in non-ambulatory children with spastic cerebral palsy. While performing a simultaneous hip/knee flexion task from the supine position, followed by return to the starting position, electromyographic and kinematic data were obtained from the right leg of eight children before and after selective dorsal rhizotomy and compared with eight age-matched controls. The electromyographic and kinematic data were combined to determine for each muscle of interest (tibialis anterior, soleus, vastus lateralis, biceps femoris) the percentage of the movement cycle for which the muscle was acting concentrically, eccentrically, isometrically or was considered inactive. Averaged over the four muscles, isometric activity decreased by 38% post-op and the time the muscles were inactive increased by 37% following surgery. The percentages of concentric and eccentric activity did not differ significantly between pre- and post-op conditions. Post-operatively, the percentage muscle activity patterns of the children with cerebral palsy more closely resembled that of the control children: averaged across all muscles and contraction types, the difference between the control children and the children with cerebral palsy was reduced by 50% following surgery. This measurement technique indicates promise as a method for quantifying muscle activity during voluntary motor tasks in non-ambulatory children with cerebral palsy.

Prosodic correlates of stress in babbling: an acoustical study

Prelinguistic babbling often seems remarkably speech-like, not because it has recognizable words but because it seems to have adult-like prosody. To quantify this impression, we compared disyllabic sequences from five infants and five adults in terms of the use of frequency, intensity, and duration to mark stress. Significantly larger values for the three acoustic variables were observed on stressed than on unstressed syllables independent of syllable position for both groups. Adults showed the correlates of utterance final syllables--lower f0, lower intensity, and longer duration; infants showed only decrease in intensity. Ratios for stressed to unstressed syllables and participation of the three variables in stress production in individual disyllables were highly similar in both groups. No bias toward the English lexical trochaic stress pattern was observed. We conclude that infants in English environments produce adult-like stress patterns before they produce lexical items, which specify stress. Acoustic and perceptual analyses are used to explore stress marking by prelinguistic infants in an English language environment. Results show that infants employ the three acoustic correlates of stress in individual syllables in a manner largely similar to that of adult speakers, although they do not show second-syllable declination effects or an English language trochaic stress bias.

On the origin of internal structure of word forms

This study shows that a corpus of proto-word forms shares four sequential sound patterns with words of modern languages and the first words of infants. Three of the patterns involve intrasyllabic consonant-vowel (CV) co-occurrence: labial (lip) consonants with central vowels, coronal (tongue front) consonants with front vowels, and dorsal (tongue back) consonants with back vowels. The fourth pattern is an intersyllabic preference for initiating words with a labial consonant-vowel-coronal consonant sequence (LC). The CV effects may be primarily biomechanically motivated. The LC effect may be self-organizational, with multivariate causality. The findings support the hypothesis that these four patterns were basic to the origin of words.

Deriving speech from nonspeech: a view from ontogeny

A comparison of babbling and early speech, word patterns of languages, and, in one instance, a protolanguage corpus, reveals three basic movement patterns: (1) a 'Frame' provided by the cycles of mandibular oscillation underlying the basic mouth close-open alternation of speech; this Frame appears in relatively 'pure' form in the tendency for labial consonants to co-occur with central vowels; (2) two other intracyclical consonant-vowel (CV) co-occurrence patterns sharing the alternation: coronal consonants with front vowels and dorsal consonants with back vowels; (3) an intercyclical tendency towards a labial consonant-vowel-coronal consonant (LC) sequence preference for word initiation. The first two patterns were derived from oral movement capabilities which predated speech. The Frame (1) may have evolved from ingestive cyclicities (e.g. chewing). The intracyclical consonant-vowel (CV) co-occurrence patterns involving tongue position constraints common to consonants and vowels (2) may result from the basic biomechanical property of inertia. The third pattern (LC) was a self-organizational result of pressures for interfacing cognition with action - a result which must have numerous analogs in other domains of movement organization.

An embodiment perspective on the acquisition of speech perception

Understanding the potential relationships between perception and production is crucial to explanation of the nature of early speech acquisition. The 'embodiment' perspective suggests that mental activity in general cannot be understood outside of the context of body activities. Indeed, universal motor factors seem to be more responsible for the distribution of early production preferences regarding consonant place and manner, and use of the vowel space than the often considerable cross-language differences in input available to the perceptual system. However, there is evidence for a perceptual basis to the establishment of a language-appropriate balance of oral-to-nasal output by the beginning of babbling, illustrating the necessary contribution of 'extrinsic' perceptual information to acquisition. In terms of representations, at least one assumption that segmental units underlying either perception or production in early phases of acquisition may be inappropriate. Our work on production has shown that the dominant early organizational structure is a relatively unitary open-close 'frame' produced by mandibular oscillation. Consideration of the role of 'intrinsic' (self-produced) perceptual information suggests that this frame may be an important basis for perceptual as well as production organization.

Obesity and osteoarthritis of the knee: hypotheses concerning the relationship between ground reaction forces and quadriceps fatigue in long-duration walking

The principal risk factors of osteoarthritis of the knee are: age, obesity and gender. It is hypothesized that long-duration walking (e. g. 20 min) in the elderly obese will lead to quadriceps fatigue. Changes in the gait pattern due to fatigue will lead to altered knee kinematics at heelstrike and consequently decreased shock absorption. This scenario will result in an increased rate of loading and possibly an increase in the overall magnitude of peak ground reaction forces, both of which could cause articular cartilage degeneration. Obese females are at an overall higher risk of developing osteoarthritis than males. This gender discrepancy may be explained by the fact that females have a higher percentage of body fat content (lower proportion of lean mass) that may increase the rate of quadriceps fatigue. These biomechanical hypotheses can be examined by studying continuous periods of walking in which ground reaction forces, knee kinematics and electromyography data are recorded.

The motor core of speech: a comparison of serial organization patterns in infants and languages

Comparison of serial organization of infant babbling and early speech with that of 10 languages reveals four movement-related design features reflecting a deep evolutionary heritage: (1) the cyclical consonant-vowel alternation underlying the syllable, a "Frame" for speech consisting of mandibular oscillation, possibly evolving from ingestive cyclicities (e.g., chewing) via visuofacial communicative cyclicities (e.g., lipsmacks); (2) three intracyclical consonant-vowel co-occurrence preferences reflecting basic biomechanical constraints-coronal consonants-front vowels, dorsal consonants-back vowels, and labial consonants-central vowels; (3) a developmental progression from above-chance to below-chance levels of intercyclical consonant repetition; (4) an ease-related labial consonant-vowel-coronal consonant sequence preference for word initiation. These design features presumably result from self-organizational responses to selection pressures, primarily determined by motor factors. No explanation for these design features is available from Universal Grammar, and, except for feature 3, perceptual-motor learning seems to have only a limited causal role in acquisition of any design feature.

Characterization of the calcaneal fat pad in diabetic and non-diabetic patients using magnetic resonance imaging

It is well known that diabetic patients have a high incidence of foot ulceration. The purpose of this study was to determine whether magnetic resonance (MR) imaging can detect changes in the composition of the calcaneal fat pad in diabetic feet. MR data were collected in vitro from amputated specimens (eight from diabetic patients and eight from non-diabetic patients) as well as in vivo from age-matched diabetic and control subjects (four subjects each group.) Three types of images were acquired: spin lattice (T1), spin-spin (T2), and magnetization transfer (MT). The in vitro results showed statistically significant differences in the T1, T2, and MT parameters between the two disease groups. The same trends were shown in the study of live subjects but the differences were not statistically significant. The differences are believed to arise from changes in the composition of the tissues as a result of the progression of diabetes.