ABSTRACT
The photon-phonon coupling at C(001)-(2 × 1) surfaces and its manifestation in far-infrared reflectance anisotropy spectra (FIR-RAS) are theoretically investigated. We solve the coupled system of equations for the electromagnetic field and lattice vibrations, described within the adiabatic bond charge model (ABCM), with the method of expansion into bulk phonon and photon modes. The calculated FIR-RAS exhibit resonances associated with zone-center surface phonons in good agreement with available HREELS experiments and predictions of vibrational modes for diamond (001)-(2 × 1) surfaces from ABCM and ab initio calculations. Interestingly, the reflectance anisotropy spectra for a C(001)-(2 × 1) surface turn out to be qualitatively different from the spectra for a Si(001)-(2 × 1) surface, reported previously.
ABSTRACT
The vast majority of periprosthetic fractures occur as the result of trauma. There are many predisposing factors for these factors, including osteopenia, neurologic disorders, medications, rheumatoid arthritis, previous arthroplasty, and infection. These same factors also increase the likelihood of fracture comminution, and the presence of poor bone quality makes fixation difficult and prone to failure.
Subject(s)
Arthroplasty, Replacement, Knee , Bone Transplantation , Femoral Fractures/surgery , Postoperative Complications , Cementation , Fractures, Comminuted/surgery , Humans , Osteotomy , Risk Factors , Transplantation, HomologousABSTRACT
Every year there are seven million new lawn mowers purchased in the United States, each of which is capable of injuring young children, especially those > 14 years of age. A total of 33 children injured by a lawn mower were reviewed to identify the mechanism of injury, to determine the factors responsible for the accident, to determine an effective treatment regime, and to evaluate the permanent impairment for these patients. Classified according to their mechanism of injury, 14 children were injured as bystanders, 13 injured as riders, and six injured as operators. Categorized according to the anatomical location of injury, there were eight head and eye injuries, 12 upper extremity injuries, and 13 lower extremity injuries. There were 13 amputations (39.3%). The treatment management was satisfactory, but 23 children had an impairment > 40% of the whole person. We believe that the incidence of these injuries can be reduced by public awareness. Each orthopaedic surgeon should take on the task of educating the public about the dangers and wounding capacity of these machines and instructing the proper safety precautions that should be taken when mowing the lawn, especially when children are involved. The bottom line is that children should not be allowed in the yard while the lawn is being mowed nor should they be allowed to mow the lawn until they are > or = 15 years of age.
Subject(s)
Household Articles , Wounds and Injuries/etiology , Accident Prevention , Adolescent , Arm Injuries/etiology , Arm Injuries/surgery , Child , Child, Preschool , Eye Injuries/etiology , Eye Injuries/surgery , Female , Head Injuries, Closed/etiology , Head Injuries, Closed/surgery , Humans , Leg Injuries/etiology , Leg Injuries/surgery , Male , Retrospective Studies , Wounds and Injuries/prevention & control , Wounds and Injuries/surgeryABSTRACT
Se estudia la importancia de las teorías etiológicas actuales de los tumores productores de prolactina (PRL). Así, los tumores productores de PRL pueden considerarse como un síndrome de múltiples etiologías, en las que participan diferentes estímulos peptidérgicos hipotalámicos. En pacientes con diagnóstico de tumor productor de PRL se estudiaron: A) la regulación dopaminérgica que estimula o inhibe la secreción de PRL, B) la neurotransmisión gabaminérgica que tambien estimula la secreción de PRL en el sistema nervioso central y lactotropo hipofisiario; y C) la vía serotoninérgica que produce liberación de PRL. Estos tipos de estímulos pueden ser la causa subyacente de la hiperplasia celular que origina la secreción de PRL .
