Showing papers by "Tulane University published in 1985"

Glenoid labrum tears related to the long head of the biceps

Abstract: Tears of the glenoid labrum were observed in 73 base ball pitchers and other throwing athletes who under went arthroscopic examination of the dominant shoul der. Most of the tears were located over the anterosu perior portion of the glenoid labrum near the origin of the tendon of the long head of the biceps muscle into the glenoid.At arthroscopy, the tendon of the long head of the biceps appeared to originate through and be continuous with the superior portion of the glenoid labrum. In many cases it appeared to have pulled the anterosuperior portion of the labrum off the glenoid. This observation was verified at arthroscopy by viewing the origin of the biceps tendon into the glenoid labrum as the muscle was electrically stimulated. With stimulation of the mus cle, the tendinous portion became quite taut, particu larly near its attachment to the glenoid labrum, and actually lifted the labrum off the glenoid.Three-dimensional high-speed cinematography with computer analysis revealed that the moment acting a...

Hellmann-Feynman, virial, and scaling requisites for the exact universal density functionals. Shape of the correlation potential and diamagnetic susceptibility for atoms

Abstract: By the Hellmann-Feynman theorem, the density n(r) of many electrons in the presence of external potential v(r) obeys the relationships F${d}^{3}$r n(r)\ensuremath{ abla}v(r)=0 and F${d}^{3}$r n(r)r\ifmmode\times\else\texttimes\fi{}\ensuremath{ abla}v(r)=0. By the virial theorem, the interacting kinetic and electron-electron repulsion expectation values obey 2T[n]+${V}_{\mathrm{ee}}$[n]=-F${d}^{3}$r n(r)r\ensuremath{\cdot}\ensuremath{ abla}[\ensuremath{\delta}T/\ensuremath{\delta}n(r)+\ensuremath{\delta}${V}_{\mathrm{ee}}$/\ensuremath{\delta}n(r)]. The exchange energy functional ${E}_{x}$[n] and potential ${v}_{x}$([n];r)\ensuremath{\equiv}\ensuremath{\delta}${E}_{x}$/\ensuremath{\delta}n(r) must satisfy ${E}_{x}$[n]+F${d}^{3}$r n(r)r\ensuremath{\cdot}\ensuremath{ abla}${v}_{x}$([n];r)=0, while the correlation energy and potential must satisfy ${E}_{c}$[n]+F${d}^{3}$r n(r)r\ensuremath{\cdot}\ensuremath{ abla}${v}_{c}$([n];r)0. Somewhat counterintuitively, it is not true that T[${n}_{\ensuremath{\gamma}}$]=${\ensuremath{\gamma}}^{2}$T[n] and ${V}_{\mathrm{ee}}$[${n}_{\ensuremath{\gamma}}$]=\ensuremath{\gamma}${V}_{\mathrm{ee}}$[n], where ${n}_{\ensuremath{\gamma}}$(r)\ensuremath{\equiv}${\ensuremath{\gamma}}^{3}$n(\ensuremath{\gamma}r) is a scaled density with scale factor \ensuremath{\gamma}\ensuremath{ e}1. In fact, it is impossible to partition the exact Hohenberg-Kohn functional into a piece that scales as ${\ensuremath{\gamma}}^{2}$ and a piece that scales as \ensuremath{\gamma}, even if complete freedom with the partitioning is allowed. Instead there are universal scaling inequalities.For instance, T[${n}_{\ensuremath{\gamma}}$]+${V}_{\mathrm{ee}}$[${n}_{\ensuremath{\gamma}}$]${\ensuremath{\gamma}}^{2}$T[n]+ \ensuremath{\gamma}${V}_{\mathrm{ee}}$[n] and T[${n}_{\ensuremath{\gamma}}$]+\ensuremath{\gamma}${V}_{\mathrm{ee}}$[${n}_{\ensuremath{\gamma}}$]g${\ensuremath{\gamma}}^{2}$(T[n ]+${V}_{\mathrm{ee}}$[n]), and consequent inequalities involving ${E}_{c}$[n]. All the above virial and scaling requisites are universal in that they are independent of external potential and they must hold for arbitrary proper n. In addition, for the ground-state energy (E) and n of any atom or molecule at its equilibrium nuclear configuration, there is the inequality E-${T}_{s}$[n], where ${T}_{s}$ is the noninteracting kinetic energy. In the closed-shell tight-binding limit, the correlation potential obeys F${d}^{3}$r n(r)r\ensuremath{\cdot}\ensuremath{ abla}${v}_{c}$([n];r)=0, and so cannot be a monotonic function of r for an atom in this limit.Further, (\ensuremath{\partial}/\ensuremath{\partial}\ensuremath{\gamma})${E}_{c}$[${n}_{\ensuremath{\gamma}}$]${\ensuremath{\Vert}}_{\ensuremath{\gamma}=1}$=E $_{c}$[n]+${T}_{c}$[n]=-F${d}^{3}$r n(r)r\ensuremath{\cdot}\ensuremath{ abla}${v}_{c}$([n];r), which implies that the exact ${E}_{c}$ should be fairly insensitive to scaling. With the help of the ionization-potential theorem, it is argued that the exact ${v}_{c}$([n];r) in an atom often has a positive part. Common approximations to the correlation potential are examined for their effects upon the highest occupied Kohn-Sham orbital energy and the density moment 〈${r}^{2}$〉, and these effects are found to be related. Further improvements needed in the approximate correlation potentials are relatively large, but not nearly so large as those recently suggested for the atoms Ne, Ar, Kr, and Xe: The discrepancy between theoretical values of 〈${r}^{2}$〉 from Hartree-Fock or configuration-interaction calculations, and experimental values from measured diamagnetic susceptibilities, is tentatively resolved in favor of theory.

Explaining husbands' participation in domestic labor

Abstract: Three hypotheses of husbands' participation in domestic labor (i.e., housework and child care) are examined: (1) the relative resources hypothesis states that the more resources (e.g., socioeconomi...

Accurate density functional for the energy: Real-space cutoff of the gradient expansion for the exchange hole.

Abstract: The density-gradient expansion of the fermion exchange hole is analyzed in real space. Unlike the local-density approximation, the second-order gradient-expansion approximation is found to violate two important properties of the exact hole: The exact hole is negative everywhere, and represents a deficit of one electron. Imposition of these exact constraints leads to an accurate new density functional for the exchange energy. Residual errors in the exchange energy for atoms are about 1% of this quantity. The new functional approximation may be generalized to include correlation.

Arthroscopy of the elbow

Abstract: A technique of diagnostic and surgical arthroscopy of the elbow is presented, and the normal intraarticular anatomy as viewed from the anterolateral, anteromedial, and posterolateral portals is described. A preliminary study of 12 patients who underwent surgical arthroscopy of the elbow demonstrated that removal of loose bodies produced the best objective and subjective results. Less satisfactory results were obtained when procedures such as capitellum and radial head chondroplasties were performed. Using a preoperative and postoperative point accumulation rating system for four objective and four subjective criteria, the following results were noted. Before surgery 50% of the patients objectively rated their elbows as satisfactory (excellent or good), whereas postoperative ratings increased to 83%. Subjectively, 17% rated their elbows as satisfactory before surgery, improving to 58% satisfactory ratings postoperatively. The only complication was a transient median nerve palsy caused by the extracapsular extravasation of a local anesthetic. From this preliminary study, it was concluded that attention to detail is essential in performing a safe, reproducible arthroscopic examination of the elbow, that arthroscopy of the elbow is an effective diagnostic procedure, and that operative elbow arthroscopy is effective in the treatment of certain elbow disorders.

An evaluation of variables influencing implant fixation by direct bone apposition.

Abstract: A systematic mechanical and histologic evaluation of design variables affecting bone apposition to various biocompatible materials was undertaken. The variables investigated included material elastic modulus, material surface texture, as well as material surface composition. The implant materials included polymethylmethacrylate (PMMA), low-temperature isotropic (LTI) pyrolytic carbon, commercially pure (C.P.) titanium, and aluminum oxide (Al2O3). Implant surface texture was varied by either polishing or grit-blasting the various materials. Implant surface composition was varied by applying a coating of ultra-low temperature isotropic (ULTI) pyrolytic carbon to the various implants. A total of 12 types of implants were evaluated in vivo by placement transcortically in the femora of adult mongrel dogs for a period of 32 weeks. Following sacrifice, mechanical push-out testing was performed to determine interface shear strength and interface shear stiffness. The results obtained from mechanical testing indicate that for implants fixed by direct bone apposition, interface stiffness and interface shear strength are not significantly affected by either implant elastic modulus or implant surface composition. Varying surface texture, however, significantly affected the interface response to the implants. For each elastic modulus group the roughened surfaced implants exhibited greater strengths than the corresponding smooth surfaced implants. Undecalcified histologic evaluation of the implants demonstrated that the roughened implants exhibited direct bone apposition, whereas the smooth implants exhibited various degrees of fibrous tissue encasement. Thus, for implants utilizing direct bone apposition fixation, it appears that of the parameters investigated, implant surface texture is the most significant.

Arthroscopy of the shoulder in the management of partial tears of the rotator cuff: a preliminary report.

Abstract: Thirty-six patients with partial tears of the supraspinatus portion of the rotator cuff underwent arthroscopic examination and debridement of the lesion. All patients, whose average age was 22 years, were involved in competitive athletics; 64% were baseball pitchers. The average duration of symptoms prior to arthroscopy was 12 months. The most common presenting complaint was pain felt in the shoulder during overhead activities. Associated pathology included tears of the glenoid labrum and partial tearing or tendinitis of the long head of the biceps tendon. Of the 34 patients available for follow-up, 26 (76%) had excellent results, three (9%) had good results, and five (15%) had poor results. Eighty-five percent of the patients returned satisfactorily to their preoperative athletic activity. Our preliminary experience with arthroscopy of the shoulder in the management of patients with partial rotator cuff tears is encouraging. Not only can a partial rotator cuff tear be debrided to initiate a healing response, but a definitive diagnosis can also be made and associated pathology identified, permitting the establishment of an appropriate rehabilitation program.

Plane waves in linear elastic materials with voids

Abstract: The behavior of plane harmonic waves in a linear elastic material with voids is analyzed. There are two dilational waves in this theory, one is predominantly the dilational wave of classical linear elasticity and the other is predominantly a wave carrying a change in the void volume fraction. Both waves are found to attenuate in their direction of propagation, to be dispersive and dissipative. At large frequencies the predominantly elastic wave propagates with the classical elastic dilational wave speed, but at low frequencies it propagates at a speed less than the classical speed. It makes a smooth but relatively distinct transition between these wave speeds in a relatively narrow range of frequency, the same range of frequency in which the specific loss has a relatively sharp peak. Dispersion curves and graphs of specific loss are given for four particular, but hypothetical, materials, corresponding to four cases of the solution.

Evidence of aluminum loading in infants receiving intravenous therapy.

Abstract: To investigate the possibility that premature infants may be vulnerable to aluminum toxicity acquired through intravenous feeding, we prospectively studied plasma and urinary aluminum concentrations in 18 premature infants receiving intravenous therapy and in 8 term infants receiving no intravenous therapy. We also measured bone aluminum concentrations in autopsy specimens from 23 infants, including 6 who had received at least three weeks of intravenous therapy. Premature infants who received intravenous therapy had high plasma and urinary aluminum concentrations, as compared with normal controls: plasma aluminum, 36.78 +/- 45.30 vs. 5.17 +/- 3.1 micrograms per liter (mean +/- S.D., P less than 0.0001); urinary aluminum:creatinine ratio, 5.4 +/- 4.6 vs. 0.64 +/- 0.75 (P less than 0.01). The bone aluminum concentration was 10 times higher in infants who had received at least three weeks of intravenous therapy than in those who had received limited intravenous therapy: 20.16 +/- 13.4 vs. 1.98 +/- 1.44 mg per kilogram of dry weight (P less than 0.0001). Creatinine clearances corrected for weight did not reach expected adult values until 34 weeks of gestation. Many commonly used intravenous solutions are found to be highly contaminated with aluminum. We conclude that infants receiving intravenous therapy have aluminum loading, which is reflected in increased urinary excretion and elevated concentrations in plasma and bone. Such infants may be at high risk for aluminum intoxication secondary to increased parenteral exposure and poor renal clearance.

Active rifting in southwestern Mexico: Manifestations of an incipient eastward spreading-ridge jump

Abstract: A major, ongoing episode of continental rifting has formed a system of three intersecting grabens in the western Mexican volcanic belt. These structures may mark the initial stage of an eastward spreading-ridge jump beneath continental crust. Eastward ridge-segment jumps have been propagating northward along this part of the East Pacific Rise for the past 12 m.y., but this is the first plate-boundary reorganization event to involve continental crust since the separation of Baja California in the Miocene. Since Pliocene time, small volumes of unusual alkaline magmas have erupted in the graben areas in close association with the more abundant, subduction-related calc-alkaline magmas erupted from andesitic stratovolcanoes. The alkaline magmas are varieties found in zones of active rifting elsewhere in the world.

A quantitative test for xerostomia. The saxon test, an oral equivalent of the schirmer test

Abstract: We describe a simple, reproducible, and low-cost test for xerostomia, which involves chewing on a folded sterile sponge for 2 minutes. Saliva production is quantitated by weighing the sponge before and after chewing. Normal control subjects produced greater than or equal to 2.75 gm of saliva in 2 minutes. Three of 32 consecutive, unselected outpatients in allergy-immunology clinics and 9 of 38 patients in rheumatology clinics had decreased saliva production, which was significantly different compared with controls (P less than 0.01). The presence of sicca symptoms was highly correlated with quantitatively abnormal tear and saliva production, according to the results of the Saxon and Schirmer's tests.

Steroid Hormone Receptors and the Nucleus

Abstract: I. Introduction THE CONCEPT that steroid hormone action is mediated by interaction with specific target tissue receptor proteins has become generally well accepted. Receptors that are not bound to hormone (unoccupied receptors) were initially described as residing in cytosolic/cytoplasmic1 compartments of many systems. Biochemical and autoradiographic procedures led to this conclusion. Additional evidence established that hormone binding induces receptor transformation2 and receptor movement from the cytosolic to the nuclear compartment (translocation), where the biological response is initiated. This review summarizes the evidence for steroid receptor action in the nucleus and discusses the recent controversy that unoccupied receptors themselves may be predominantly associated with nuclear components in vivo. This summary, rather than being an exhaustive review of one or two receptor systems, emphasizes the parallel development of these concepts in multiple steroid hormone receptor systems,3 in part by r...

Outcomes of Role Stress: A Multisample Constructive Replication

Abstract: Responses from four separate samples of accountants and hospital employees provided a constructive replication of the Bedeian and Armenakis (1981) model of the causal nexus between role stress and selected outcome variables. We investigated the relationship between both role ambiguity and role conflict--as specific forms of role stress--and job-related tension, job satisfaction, and propensity to leave, using LISREL IV, a technique capable of providing statistical data for a hypothesized population model, as well as for specific causal paths. Results, which support the Bedeian and Armenakis model, are discussed in light of previous research.

Differences in regulatory sequences of naturally occurring JC virus variants

Abstract: The regulatory region was sequenced for DNAs representative of seven independent isolates of JC virus, the probable agent of progressive multifocal leukoencephalopathy. The isolates included an oncogenic variant (MAD-4), an antigenic variant (MAD-11), and two different isolates derived from the urine (MAD-7) and from the brain (MAD-8) of the same patient. The representative DNAs were molecularly cloned directly from diseased brain tissue and from human fetal glial cells infected with the corresponding isolated viruses. The regulatory sequences of these DNAs were compared with those of the prototype isolate, MAD-1, sequenced previously (R. J. Frisque, J. Virol. 46:170-176, 1983). We found that the regulatory region of JC viral DNA is highly variable due to complex alterations of the previously described 98-base-pair repeat of MAD-1 DNA. On the basis of these alterations, there are two general types of JC virus. There were no consistent alterations in regulatory sequences which could distinguish brain tissue DNAs from tissue culture DNAs. Furthermore, for each isolate except MAD-1 (R. J. Frisque, J. Virol. 46:170-176, 1983), the regulatory regions of brain tissue and tissue culture DNAs were not identical. The arrangement, sequence, or both of potential regulatory elements (TATA sequence, GGGXGGPuPu, tandem repeats) of JC viral DNAs are sufficiently different from those in other viral and eucaryotic systems that they may effect the unique properties of this slow virus.

The viscoelastic behavior of linear elastic materials with voids

Abstract: It is shown that the constitutive equations for a linear elastic material with voids imply a viscoelastic stress-strain relation known as the “standard linear solid” in the case of quasi-static, homogeneous deformations in the absence of self-equilibrated body forces. It is noted that, even for deformations that are dynamic and/or inhomogeneous the viscoelastic behavior is still qualitatively similar to that predicted by the standard linear solid model.

Response to Measles Vaccine in Haitian Infants 6 to 12 Months Old: Influence of Maternal Antibodies, Malnutrition, and Concurrent Illnesses

Abstract: To study the factors affecting the serologic response to measles vaccination, we evaluated 595 Haitian infants from 6 through 12 months of age, and their mothers, at the beginning of an immunization program. Thirty-four per cent of the infants had preexisting serologic evidence of measles infections by 11 months of age. Among infants more than nine months of age, those who had had measles had a significantly lower nutritional status than those who had not (P less than 0.01). After vaccination, seroconversion rates increased from 45 per cent at 6 months to 100 per cent at 12 months. The lowest rate of vaccine failure compatible with acceptably low rates of natural infections could be achieved by vaccination after eight months of age. Infants born to mothers with low levels of antibody to measles (hemagglutination-inhibition antibody titers less than 1:40) were significantly more likely to have had natural measles (P less than 0.01) or to have seroconversion after vaccination (P less than 0.001) at 6 to 10 months of age than were infants born to mothers with higher of age than were infants born to mothers with higher titers. Malnutrition and acute infections did not affect seroconversion rates. These data support the World Health Organization recommendation to administer measles vaccine in under-developed countries as soon after nine months of age as possible, regardless of nutritional status or the presence of minor illnesses.

What do the Kohn-Sham Orbital Energies Mean? How do Atoms Dissociate?

Abstract: Hohenberg and Kohn1 have demonstrated the existence of a functional Ey [n] which, when minimized over trial densities \( n(\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\thicksim}$}}\to {r} )\) integrating Yo N electrons, yields the exact ground-state energy E and density for N electrons subject to an external potential \( v(\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\thicksim}$}}\to {r} )\).