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1.
J Exp Anal Behav ; 120(3): 320-329, 2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-37464552

RESUMO

In separate chambers, responding by two pairs of pigeons was reinforced under concurrent random-ratio schedules of reinforcement. For each pair, the birds' schedules were coupled in such a manner that left- and right-key reinforcement probabilities were determined by the key being pecked by the other pigeon of the pair. In this way, a reinforcement matrix, like that of the popular Prisoner's Dilemma game of game theory, was created. The responding of all subjects soon gravitated to the choice combination identified by the mathematician John Nash as the equilibrium of the Prisoner's Dilemma game. This was found both before and after reversal of contingencies on the keys. In a second experiment, with a single pair of pigeons, stimuli signaling the choice of the paired pigeon had little lasting effect: responding again gravitated to the game's equilibrium. The results affirm earlier findings, demonstrating that Skinner's principle of positive reinforcement, together with Nashian mathematics, entirely accounts for iterative game-theoretic behavior. They extend these findings to the so-called free operant: to schedules of reinforcement in which responding is not constrained by stimulus-response sequencing (i.e., a trials procedure). The coupled schedule of reinforcement introduced here offers significant promise for the experimental analysis of economic and social behaviors.


Assuntos
Dilema do Prisioneiro , Reforço Psicológico , Animais , Humanos , Comportamento Social , Columbidae , Teoria dos Jogos , Comportamento Cooperativo
2.
Plant Dis ; 107(7): 2185-2196, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36480730

RESUMO

Boxwood blight (BB) caused by Calonectria pseudonaviculata (Cps), an economically devastating disease affecting everyone in the supply chain from growers to gardeners, was first officially documented in the United States in 2011. This disease has taken a heavy toll on boxwood, an iconic landscape plant and the number one evergreen nursery crop. Instead of abandoning boxwood production and switching to other evergreens, growers in the United States, informed by the latest research, have elected to combat this disease. One of the strategies employed has been to shift boxwood production from highly susceptible to less-susceptible cultivars. The objective of this study was to investigate the ongoing shift by comparing boxwood sales of 17 selected nurseries from seven states across the country in 2011, 2016, and 2021. Results revealed an additional 21.24% (from 38.58 to 60.04%) in sales of less-susceptible boxwood cultivars in 2021 compared with 2016. The less-susceptible cultivars responsible for increased boxwood sales are 'Winter Gem', 'Wintergreen', 'SB 300' (Freedom), 'SB 108' (Independence), and 'Little Missy'. The potential for long-term positive impact on sustainable boxwood production and plantings in the United States through the use of less-susceptible cultivars is discussed. This shift in boxwood choices builds crop health into new plantings of this landmark plant and sustains growth in demand for boxwood. This sets a new example of sustainable protection for a crop that is under serious pressure from an invasive pathogen.


Assuntos
Buxus , Hypocreales , Estados Unidos , Doenças das Plantas/prevenção & controle
3.
J Allied Health ; 50(2): 140-145, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34061934

RESUMO

PURPOSE: Increased fall risk has been linked to age, being female, and age-related changes in the postural control system. The purpose of this study was to determine if a portable balance system could predict fall risk by determining the relationship among the modified Clinical Test for Sensory Interaction on Balance (mCTSIB) scores, age, the Activities-specific Balance Confidence Scale (ABC) score, and the Berg Balance Scale (BBS) score in community-dwelling older women. Insight into these relationships may facilitate early intervention and decrease fall risk in older women. METHODS: This study was a non-experimental, prospective, cross-sectional, exploratory analysis to determine the relationship among the mCTSIB, age, ABC, and BBS. Women aged 65 years and over were selected from two independent living facilities using a sample of convenience (n=42). RESULTS: The mCTSIB firm surface, eyes open and the ABC predicted fall risk (BBS) scores, F(2, 36)=35.72, p<0.001, R2=0.67, but adding age did not significantly improve the model, b= -0.17, t(36)= -1.71, p=0.10. CONCLUSION: A portable balance system may be an effective screening tool to predict fall risk in community-dwelling older women and may be used by a variety of allied health professionals. Postural sway, and perceived balance, predicted fall risk scores (BBS). More specifically, data obtained from the mCTSIB firm surface, eyes open test condition when combined with ABC scores could lead to identification of increased fall risk, allowing clinicians to recommend early treatment intervention to prevent future falls.


Assuntos
Acidentes por Quedas , Vida Independente , Idoso , Estudos Transversais , Feminino , Humanos , Equilíbrio Postural , Estudos Prospectivos
4.
J Am Pharm Assoc (2003) ; 61(5): e45-e47, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33966959

RESUMO

An intersection of the pharmacy profession and public health is the role of the specialty pharmacist. The specialty pharmacist is in a unique position to prevent unnecessary financial burden on the health care system by preventing community-acquired needlestick injuries through patient education regarding the proper disposal of sharps. Many specialty medications are injectable agents with varying injection frequencies ranging from multiple injections per day to 1 dose per year. Programs should be implemented at specialty pharmacies to fill this patient education gap. This distinct service to patients and the profession will continue to grow alongside the niche of specialty pharmacy.


Assuntos
Assistência Farmacêutica , Farmácias , Farmácia , Humanos , Farmacêuticos , Saúde Pública
5.
RSC Adv ; 10(27): 16038-16044, 2020 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-35493645

RESUMO

Trimethylamine-boranecarboxylic acid (CH3)3N-BH2COOH and other amine carboxyboranes have been observed to undergo slow decarbonylation in neutral aqueous solution. This reaction, when it occurs in vivo, may have a therapeutic effect by delivering low concentrations of carbon monoxide over an extended period. In order to identify a possible mechanistic pathway for decarbonylation, the smallest tertiary amine derivative and its corresponding carboxylate ion were studied using CCSD(T)/PCM/6-311++G(2d,p)//M06-2X/PCM/6-311++G(2d,p) model chemistry. The proposed mechanistic pathway begins with a trimethylamine boranecarboxylate ion, which first undergoes an internal substitution reaction (SNi) to give free amine and the carboxyborane anion BH2COO-. The latter cyclic ion then releases CO via a rapid chelotropic fragmentation. The role of water solvent in these reactions was explored by structural and energetic analysis of hydrogen-bonded complexes. It was found that complexation with water inhibits dissociation of trimethylamine by stabilizing the trimethylamine carboxyborane anion, whereas water accelerates CO loss by stabilizing the polar chelotropic transition state.

6.
CBE Life Sci Educ ; 18(4): ar65, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31782694

RESUMO

In efforts to increase scientific literacy and enhance the preparation of learners to pursue careers in science, there are growing opportunities for students and teachers to engage in scientific research experiences, including course-based undergraduate research experiences (CUREs), undergraduate research experiences (UREs), and teacher research experiences (TREs). Prior literature reviews detail a variety of models, benefits, and challenges and call for the continued examination of program elements and associated impacts. This paper reports a comprehensive review of 307 papers published between 2007 and 2017 that include CURE, URE, and TRE programs, with a special focus on research experiences for K-12 teachers. A research-supported conceptual model of science research experiences was used to develop a coding scheme, including participant demographics, theoretical frameworks, methodology, and reported outcomes. We summarize recent reports on program impacts and identify gaps or misalignments between goals and measured outcomes. The field of biology was the predominant scientific disciplinary focus. Findings suggest a lack of studies explicitly targeting 1) participation and outcomes related to learners from underrepresented populations, 2) a theoretical framework that guides program design and analysis, and, for TREs, 3) methods for translation of research experiences into K-12 instructional practices, and 4) measurement of impact on K-12 instructional practices.


Assuntos
Currículo , Docentes , Modelos Educacionais , Pesquisa , Ciência/educação , Universidades , Autoria , Humanos
8.
Am J Otolaryngol ; 38(4): 442-446, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28413076

RESUMO

PURPOSE: The purpose of this study was to determine whether Meniere's disease (MD) produces endolymphatic cavity size changes that are detectable using unenhanced high-resolution T2-weighted MRI. MATERIALS & METHODS: This retrospective case-control study included patients with documented MD who had a high-resolution T2-weighted or steady-state free procession MRI of the temporal bones within one month of diagnosis, between 2002 and 2015. Patients were compared to age- and sex- matched controls. Cross sectional area, length, and width of the vestibule and utricle were measured in both ears along with the width of the basal turn of the cochlea and its endolymphatic space. Absolute measurements and ratios of endolymph to perilymph were compared between affected, contralateral, and control ears using analysis of variance and post-hoc pairwise comparisons. RESULTS: Eighty-five case-control pairs were enrolled. Mean utricle areas for affected, contralateral, and control ears were 0.038cm2, 0.037cm2, and 0.033cm2. Mean area ratios for affected, contralateral, and control ears were 0.32, 0.32, and 0.29. There was a statistically significant difference between groups for these two variables; post-hoc comparisons revealed no difference between affected and contralateral ears in Meniere's patients, while ears in control patients were different from the ears of patients with MD. All other measurements failed to show significant differences. CONCLUSIONS: Enlargement of the endolymphatic cavity can be detected using non-contrast T2-weighted MRI. MRI, using existing protocols, can be a useful diagnostic tool for the evaluation of MD, and intratympanic or delayed intravenous contrast may be unnecessary for this diagnosis.


Assuntos
Imageamento por Ressonância Magnética , Doença de Meniere/diagnóstico por imagem , Adulto , Idoso , Cóclea/diagnóstico por imagem , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Curva ROC , Estudos Retrospectivos , Vestíbulo do Labirinto/diagnóstico por imagem
9.
J Phys Chem A ; 119(41): 10390-8, 2015 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-26401726

RESUMO

Sulfur dioxide-pyridine complex formation was reinvestigated using Fourier transform infrared (FTIR) spectroscopy and computational methods. The SO2-pyridine dimer has been proposed to have a v-shaped, Cs-symmetric structure based on the microwave spectrum; however, recent research showing the occurrence of X···H-C hydrogen bonds in noncovalent complexes suggested that the structure of the complex should be re-examined. The FTIR spectrum of the dimer was obtained by numerical analysis of the spectra of pyridine-SO2 mixtures in CCl4. The spectrum showed ortho C-H stretching modes consistent with a C1-symmetric structure containing a S-O bond oriented approximately coplanar with the pyridine ring and adjacent to an ortho C-H moiety. The C1 structure, which was identified as the global minimum by various density functional theory and correlated ab initio calculations, is also consistent with the out-of-plane second moment (Pbb) value previously determined by microwave spectroscopy. The complex is converted to its mirror image via three possible Cs-symmetric transition states: v-shaped, bisected, and flat. At the M06-2X/6-311++G(2d,p) level of theory, the rotational barriers (ΔG(o‡)) are 1.40, 1.87, and 3.63 kcal mol(-1), respectively. Natural bond order analysis indicated the asymmetric complex is stabilized both by N→S donation and back-donation from O to antibonding orbitals on pyridine. Atoms in molecules calculations identified a bond critical point within the O···H-C gap consistent with a normal, albeit weak, hydrogen bond. Theoretical studies also identified a high-energy sandwich-type dimer with Cs symmetry, and a C2-symmetric SO2-pyridine2 trimer.


Assuntos
Piridinas/química , Teoria Quântica , Dióxido de Enxofre/química , Dimerização , Estrutura Molecular , Espectroscopia de Infravermelho com Transformada de Fourier
10.
Rev Sci Instrum ; 86(7): 071301, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26233339

RESUMO

We describe the development, launch into space, and initial results from a prototype wide field-of-view soft X-ray imager that employs lobster-eye optics and targets heliophysics, planetary, and astrophysics science. The sheath transport observer for the redistribution of mass is the first instrument using this type of optics launched into space and provides proof-of-concept for future flight instruments capable of imaging structures such as the terrestrial cusp, the entire dayside magnetosheath from outside the magnetosphere, comets, the Moon, and the solar wind interaction with planetary bodies like Venus and Mars [Kuntz et al., Astrophys. J. (in press)].

11.
PLoS One ; 8(12): e82976, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24391731

RESUMO

Breastfeeding has immense public health value for mothers, babies, and society. But there is an undesirably large gap between the number of new mothers who undertake and persist in breastfeeding compared to what would be a preferred level of accomplishment. This gap is a reflection of the many obstacles, both physical and psychological, that confront new mothers. Previous research has illuminated many of these concerns, but research on this problem is limited in part by the unavailability of a research instrument that can measure the key differences between first-time mothers and experienced mothers, with regard to the challenges they face when breastfeeding and the instructional advice they require. An instrument was designed to measure motivational complexity associated with sustained breast feeding behaviour; the Breastfeeding Motivational Measurement Scale. It contains 51 self-report items (7 point Likert scale) that cluster into four categories related to perceived value of breast-feeding, confidence to succeed, factors that influence success or failure, and strength of intentions, or goal. However, this scale has not been validated in terms of its sensitivity to profile the motivation of new mothers and experienced mothers. This issue was investigated by having 202 breastfeeding mothers (100 first time mothers) fill out the scale. The analysis reported in this paper is a three factor solution consisting of value, midwife support, and expectancies for success that explained the characteristics of first time mothers as a known group. These results support the validity of the BMM scale as a diagnostic tool for research on first time mothers who are learning to breastfeed. Further research studies are required to further test the validity of the scale in additional subgroups.


Assuntos
Aleitamento Materno/psicologia , Mães/psicologia , Motivação , Feminino , Humanos , Lactente , Recém-Nascido , Gravidez , Reprodutibilidade dos Testes , Inquéritos e Questionários
12.
J Phys Chem A ; 114(50): 13182-8, 2010 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-21117658

RESUMO

We report the first theoretical study of noncovalent and covalent interactions in formic acid (FA)-SO(2) complexes. Using ab initio and DFT model chemistries, five stable noncovalent complexes were identified, as well as a covalent adduct, formic sulfurous anhydride HOSO(2)CHO. syn-FA is predicted to form two nonplanar bidentate complexes with SO(2): the more stable one contains a normal hydrogen bond donated by OH, and the less stable one contains a blue-shifted hydrogen bond donated by CH. Both are stabilized by charge transfer from FA to SO(2). anti-FA forms three planar complexes of nearly equal energy containing OH-to-SO(2) hydrogen bonds. Formic sulfurous anhydride forms via an endothermic concerted cycloaddition. Natural bond orbital analysis showed that the bidentate SO(2)-FA complexes are stabilized by n → π* donation from FA to SO(2), and back-donation from SO(2) n and π* orbitals into FA σ(OH)* or σ(CH)* orbitals. The bidentate formic acid-SO(2) complex that contains an O-H···O hydrogen bond is more stable than the similar nitric acid-SO(2) complex. The latter contains a stronger hydrogen bond but shows no O→S charge transfer interaction.

13.
J Anat ; 216(1): 48-61, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19929910

RESUMO

Facial size reduction and facial retraction are key features that distinguish modern humans from archaic Homo. In order to more fully understand the emergence of modern human craniofacial form, it is necessary to understand the underlying evolutionary basis for these defining characteristics. Although it is well established that the cranial base exerts considerable influence on the evolutionary and ontogenetic development of facial form, less emphasis has been placed on developmental factors intrinsic to the facial skeleton proper. The present analysis was designed to assess anteroposterior facial reduction in a pig model and to examine the potential role that this dynamic has played in the evolution of modern human facial form. Ten female sibship cohorts, each consisting of three individuals, were allocated to one of three groups. In the experimental group (n = 10), microplates were affixed bilaterally across the zygomaticomaxillary and frontonasomaxillary sutures at 2 months of age. The sham group (n = 10) received only screw implantation and the controls (n = 10) underwent no surgery. Following 4 months of post-surgical growth, we assessed variation in facial form using linear measurements and principal components analysis of Procrustes scaled landmarks. There were no differences between the control and sham groups; however, the experimental group exhibited a highly significant reduction in facial projection and overall size. These changes were associated with significant differences in the infraorbital region of the experimental group including the presence of an infraorbital depression and an inferiorly and coronally oriented infraorbital plane in contrast to a flat, superiorly and sagittally infraorbital plane in the control and sham groups. These altered configurations are markedly similar to important additional facial features that differentiate modern humans from archaic Homo, and suggest that facial length restriction via rigid plate fixation is a potentially useful model to assess the developmental factors that underlie changing patterns in craniofacial form associated with the emergence of modern humans.


Assuntos
Evolução Biológica , Suturas Cranianas/crescimento & desenvolvimento , Ossos Faciais/crescimento & desenvolvimento , Envelhecimento/patologia , Animais , Placas Ósseas , Cefalometria/métodos , Humanos , Mandíbula/crescimento & desenvolvimento , Desenvolvimento Maxilofacial/fisiologia , Modelos Animais , Crânio/crescimento & desenvolvimento , Sus scrofa
14.
Ground Water ; 47(4): 587-90, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19583592

RESUMO

The Kansas Geological Survey (KGS) developed a semianalytical solution for slug tests that incorporates the effects of partial penetration, anisotropy, and the presence of variable conductivity well skins. The solution can simulate either confined or unconfined conditions. The original model, written in FORTRAN, has a text-based interface with rigid input requirements and limited output options. We re-created the main routine for the KGS model as a Visual Basic macro that runs in most versions of Microsoft Excel and built a simple-to-use Excel spreadsheet interface that automatically displays the graphical results of the test. A comparison of the output from the original FORTRAN code to that of the new Excel spreadsheet version for three cases produced identical results.


Assuntos
Monitoramento Ambiental/métodos , Software , Interface Usuário-Computador , Movimentos da Água
15.
Ground Water ; 46(4): 570-8, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18384596

RESUMO

The U.S. Environmental Protection Agency has established several methods to delineate wellhead protection areas (WHPAs) around community wells in order to protect them from surface contamination sources. Delineating a WHPA often requires defining the capture zone for a well. Generally, analytical models or arbitrary setback zones have been used to define the capture zone in areas where little is known about the distribution of hydraulic head, hydraulic conductivity, or recharge. Numerical modeling, however, even in areas of sparse data, offers distinct advantages over the more simplified analytical models or arbitrary setback zones. The systematic approach discussed here calibrates a numerical flow model to regional topography and then applies a matrix of plausible recharge to hydraulic conductivity ratios (R/K) to investigate the impact on the size and shape of the capture zone. This approach does not attempt to determine the uncertainty of the model but instead yields several possible capture zones, the composite of which is likely to contain the actual capture zone. A WHPA based on this composite capture zone will protect ground water resources better than one based on any individual capture zone. An application of the method to three communities illustrates development of the R/K matrix and demonstrates that the method is particularly well suited for determining capture zones in alluvial aquifers.


Assuntos
Abastecimento de Água/normas , Calibragem , Sensibilidade e Especificidade , Estados Unidos , United States Environmental Protection Agency
16.
Toxicol Appl Pharmacol ; 222(1): 122-8, 2007 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-17459441

RESUMO

Many biological subdisciplines that regularly assess dose-response relationships have identified an evolutionarily conserved process in which a low dose of a stressful stimulus activates an adaptive response that increases the resistance of the cell or organism to a moderate to severe level of stress. Due to a lack of frequent interaction among scientists in these many areas, there has emerged a broad range of terms that describe such dose-response relationships. This situation has become problematic because the different terms describe a family of similar biological responses (e.g., adaptive response, preconditioning, hormesis), adversely affecting interdisciplinary communication, and possibly even obscuring generalizable features and central biological concepts. With support from scientists in a broad range of disciplines, this article offers a set of recommendations we believe can achieve greater conceptual harmony in dose-response terminology, as well as better understanding and communication across the broad spectrum of biological disciplines.


Assuntos
Adaptação Fisiológica , Biologia , Relação Dose-Resposta a Droga , Estresse Fisiológico , Terminologia como Assunto , Animais , Humanos
17.
Implant Dent ; 15(4): 377-85, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17172956

RESUMO

OBJECTIVES: The objectives of this work were to: (1) establish methodology for pretreating osteoblast-like cells in vitro with dexamethasone to cause glucocorticoid-induced osteoporosis, (2) perform quantitative and qualitative assessments of cellular attachment of osteoporosis-like osteoblasts when grown on implant surfaces of differing roughness, (3) and explore the hypothesis that dexamethasone-treated osteoblasts have altered cell attachment properties by focal adhesion disassembly and decreased tyrosine phosphorylation of the focal adhesion tyrosine kinase. METHODS: Osteoblasts were cultured with dexamethasone (10(-7) and 10(-6) M) for up to 4 days of incubation to induce osteoporosis-like conditions. Cellular attachment assays demonstrated the effect of dexamethasone treatments on cellular attachment properties of osteoblasts. Qualitative data were obtained utilizing immunofluorescent microscopy and Western blotting. Focal adhesion kinase (FAK) immunoprecipitation and tyrosine-phosphorylation Western blots were obtained from dexamethasone-treated human embryonic palatal mesenchymal- 1486 osteoblast cultures supplemented with ascorbate and beta-glycerol phosphate medium. RESULTS: Cellular attachment was significantly greater (P < 0.05) with non-dexamethasone-treated osteoblasts (92%) as compared to dexamethasone-treated osteoblasts after 1 (72%), 2 (63%), and 4 days (53%) of exposure. Dexamethasone-treated osteoblasts were viable and capable of proliferation, suggesting that the reduction of cellular attachment may be related to these cell adhesion processes. Immunofluorescent microscopy of both dexamethasone-treated osteoblasts and non-dexamethasone-treated osteoblasts failed to show any relative difference in the disassembly of focal adhesions and actin filaments. Extended dexamethasone treatment periods (up to 3 weeks) showed changes in the levels of FAK and FAK-phosphotyrosine in human embryonic palatal mesenchymal-1486 osteoblasts. CONCLUSIONS: The protocol used in this study demonstrated a glucocorticoid-induced osteoporosis-like suppression of osteoblasts. FAK disassembly was not a significant factor in short period; however, FAK protein levels and phosphotyrosine signaling on FAK were affected after 1-week exposure to dexamethasone. Phosphorylated FAK was not associated with the rise in the level of FAK, further indicating the possibility of FAK involvement in reduced cell attachment.


Assuntos
Implantes Dentários , Dexametasona/efeitos adversos , Glucocorticoides/efeitos adversos , Osteoblastos/efeitos dos fármacos , Osteoporose/induzido quimicamente , Células 3T3 , Animais , Antioxidantes/farmacologia , Ácido Ascórbico/farmacologia , Western Blotting , Adesão Celular/efeitos dos fármacos , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Proteína-Tirosina Quinases de Adesão Focal/efeitos dos fármacos , Glicerofosfatos/farmacologia , Humanos , Imunoprecipitação , Camundongos , Microscopia Eletrônica de Varredura , Osteoporose/patologia , Fosforilação/efeitos dos fármacos , Propriedades de Superfície , Titânio/química , Tirosina/efeitos dos fármacos
18.
Aviat Space Environ Med ; 77(12): 1244-51, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17183920

RESUMO

INTRODUCTION: Aviation spatial disorientation mishaps remain a concern, especially due to their fatality rate. Some of the most insidious disorientations are due to vestibular stimuli in the absence of visual cues. A category of such disorientations are known as somatogyral illusions. METHODS: To determine the effects of spin rate and duration on the perception of the somatogyral illusion, we examined the subjective response of pilots and non-pilots to rotation around the yaw axis in a flight simulator in a manner that would mimic two vestibular illusions found in flight: the washout of the semi-circular canals following sustained turns, and the illusory counter-rotation following return to straight and level flight. There were 29 subjects (14 pilots) who were seated blindfolded in a flight simulator which accelerated to constant plateau rotation rates of 20, 70, and 120 degrees x s(-1) and then decelerated to stationary; plateaus were 10, 20, or 40 s. Subjects reported 1) the time when the perception of rotation ceased (i.e., the subjective time until washout was reached); 2) the relative magnitude of the counter-rotation experienced; and 3) the time until the perception of counter-rotation ceased. Subjects also manipulated a slider to provide a continuous subjective measure of their experience of rotation. RESULTS: The two time measures increased with increases in both the duration and magnitude of the spin. The increase in perceived washout time with spin rate was non-linear (geometric). There was an interaction between spin duration and spin rate on the experience of illusory counter-rotation magnitude such that at low rates, spin duration had no effect, but its effect increased at faster rates. The time constant of adaptation of the semicircular canals was estimated to be 8.3 s. DISCUSSION: The effects were validated against a model of semicircular canal and cupola adaptation, which predicted the data with high accuracy. Pilots and non-pilots did not differ in their illusory experience.


Assuntos
Medicina Aeroespacial , Simulação por Computador , Ilusões , Percepção de Movimento/fisiologia , Rotação , Vestíbulo do Labirinto/fisiologia , Adaptação Fisiológica , Adolescente , Adulto , Humanos
19.
Am J Orthod Dentofacial Orthop ; 130(2): 218-23, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16905067

RESUMO

INTRODUCTION: Conventional orthodontic treatment of vertical or anterior maxillary excess by growth modification can be problematic in children because of the high levels of patient compliance required. The purpose of this preliminary study was to investigate the use of rigid skeletal fixation to modify facial bone growth without compliance. METHODS: Three 30-day old female pigs from the same litter were included in phase I. Pediatric miniplates were rigidly fixated with monocortical screws in the experimental pig to bridge the zygomaticomaxillary suture and both the frontonasal and nasomaxillary sutures, bilaterally. In the sham experimental pig, the same surgical protocol was followed, but miniplates were omitted (ie, screw placement only). In the control pig, surgery was not performed. All 3 pigs were housed and fed a normal diet under identical conditions postoperatively for 63 days; then they were killed, their right hemi-skulls were prepared for and underwent 3-dimensional coordinate landmark analysis, and en-bloc specimens from the zygomaticomaxillary, frontonasal, and nasomaxillary sutures of the left hemi-skulls underwent histologic analysis. Two 50-day-old female pigs from the same litter were used in phase II. The same experimental protocol was followed as before for the experimental pig and the sham experimental pig. Both pigs were fed a normal diet for 105 days; then they were killed, and their skulls were prepared for and underwent 3-dimensional coordinate landmark analysis. RESULTS: Rigid plating restricted zygomaticolacrimal suture length, maxillary bone length, nasal bone length, midfacial breadth, and frontal bone length by an average of -14% to -15% (range, -4% to -36%). No growth differences were noted between the animals in maxillary height, mid-premaxillary length, bregma-lambda length, palatal lengths, or mandibular length. Also, plating the sutures produced a clear depressed concavity in the infraorbital region, altered the alignment of the infraorbital plane lateral to the concavity, inhibited the anterior migration of the maxillary tuberosity, and resulted in raised folding on the bony surface adjacent to the zygomaticomaxillary suture. CONCLUSIONS: Rigidly fixating frontonasomaxillary and zygomaticomaxillary sutures inhibits growth of facial bones and might provide a means of restricting excess growth without having to rely on patient compliance. In addition, these altered growth patterns in the plated pig model produced similar and potentially homologous infraorbital features shared by living humans in comparison with ancestral fossil forms.


Assuntos
Ossos Faciais/crescimento & desenvolvimento , Aparelhos Ortodônticos Funcionais , Ortodontia Interceptora/instrumentação , Animais , Placas Ósseas , Suturas Cranianas/crescimento & desenvolvimento , Feminino , Desenvolvimento Maxilofacial , Modelos Animais , Procedimentos de Ancoragem Ortodôntica , Sus scrofa
20.
Biochim Biophys Acta ; 1764(2): 230-8, 2006 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-16290167

RESUMO

The 31P NMR spectroscopy of three pyridoxal 5'-phosphate-dependent enzymes, monomeric D-serine dehydratase, tetrameric dialkylglycine decarboxylase and tetrameric tyrosine phenol-lyase, whose enzymatic activities are dependent on alkali metal ions, was studied. 31P NMR spectra of the latter two enzymes have never been reported, their 3D-structures, however, are available. The cofactor phosphate chemical shift of all three enzymes changes by approximately 3 ppm as a function of pH, indicating that the phosphate group changes from being monoanionic at low pH to dianionic at high pH. The 31P NMR signal of the phosphate group of pyridoxal 5'-phosphate provides a measure of the active site changes that occur when various alkali metal ions are bound. Structural information is used to assist in the interpretation of the chemical shift changes observed. For D-serine dehydratase, no structural data are available but nevertheless the metal ion arrangement in the PLP binding site can be predicted from 31P NMR data.


Assuntos
Carboxiliases/química , Hidroliases/química , Espectroscopia de Ressonância Magnética , Fosfato de Piridoxal/química , Tirosina Fenol-Liase/química , Cátions Monovalentes/química , Bactérias Gram-Negativas/enzimologia , Isótopos de Fósforo/química , Potássio/química , Conformação Proteica , Sódio/química
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