Derivation of effective spin models from a three band model for CuO_2-planes

The derivation of effective spin models describing the low energy magnetic properties of undoped CuO_2-planes is reinvestigated. Our study aims at a quantitative determination of the parameters of effective spin models from those of a multi-band model and is supposed to be relevant to the analysis of recent improved experimental data on the spin wave spectrum of La_2CuO_4. Starting from a conventional three-band model we determine the exchange couplings for the nearest and next-nearest neighbor Heisenberg exchange as well as for 4- and 6-spin exchange terms via a direct perturbation expansion up to 12th (14th for the 4-spin term) order with respect to the copper-oxygen hopping t_pd. Our results demonstrate that this perturbation expansion does not converge for hopping parameters of the relevant size. Well behaved extrapolations of the couplings are derived, however, in terms of Pade approximants. In order to check the significance of these results from the direct perturbation expansion we employ the Zhang-Rice reformulation of the three band model in terms of hybridizing oxygen Wannier orbitals centered at copper ion sites. In the Wannier notation the perturbation expansion is reorganized by an exact treatment of the strong site-diagonal hybridization. The perturbation expansion with respect to the weak intersite hybridizations is calculated up to 4th order for the Heisenberg coupling and up to 6th order for the 4-spin coupling. It shows excellent convergence and the results are in agreement with the Pade approximants of the direct expansion. The relevance of the 4-spin coupling as the leading correction to the nearest neighbor Heisenberg model is emphasized.Comment: 27 pages, 10 figures. Changed from particle to hole notation, right value for the charge transfer gap used; this results in some changes in the figures and a higher value of the ring exchang

Systematic Mapping of the Hubbard Model to the Generalized t-J Model

The generalized t-J model conserving the number of double occupancies is constructed from the Hubbard model at and in the vicinity of half-filling at strong coupling. The construction is realized by a self-similar continuous unitary transformation. The flow equation is closed by a truncation scheme based on the spatial range of processes. We analyze the conditions under which the t-J model can be set up and we find that it can only be defined for sufficiently large interaction. There, the parameters of the effective model are determined.Comment: 16 pages, 13 figures included. v2: Order of sections changed. Calculation and discussion of apparent gap in Section IV.A correcte

Alteration in corticospinal excitability, talocrural joint range of motion, and lower extremity function following manipulation in non-disabled individuals

Background: Clinical outcomes of manual therapy procedures, including manipulation, have been studied. However, mechanisms underlying observed improvements remain unclear. Objective: To determine the effect of ankle joint manipulation on corticospinal excitability, ankle dorsiflexion range of motion (DF ROM), and lower extremity functional behavior in nondisabled individuals. Method: Six nondisabled individuals (age range: 31-50 years) received the main outcomes measurements of this study, before and after long axis distraction manipulation of the talocrural joint. Main outcomes measures were motor evoked potential (MEP) amplitude of gastrocnemius (GN) and tibialis anterior (TA) using transcranial magnetic stimulation, ankle DF ROM with the knee flexed and extended using standard goniometric techniques, and unilateral anterior squat reach (ASR) distance. All subjects received the main outcomes measures. Results: Significant increase in GN MEP amplitude (P \u3c .05), but not TA MEP amplitude, were documented following intervention. Significant improvements also were noted in ankle DF ROM with knee extended and flexed (P \u3c .001) and ASR distance (P \u3c .05) Significant correlations were found between standardized change in GN MEP amplitude and ankle dorsiflexion with knee flexed (ρ = .582, ρ 2 = .339, P \u3c .01), and standardized changes in GN MEP amplitude and ASR distance (ρ = .601, ρ 2 = .361, P \u3c .01). Conclusions: Increased corticospinal excitability appears to mediate improvements in ankle DF ROM and lower extremity function following long axis distraction manipulation 1 Assistant Professor, Thomas J. Long School of Pharmacy and Health Sciences, University of the Pacific, to the talocrural joint in nondisabled individuals. These results establish comparative values with which to compare the corticospinal responses to manual therapy intervention in individuals with pathology. INTRODUCTION Ankle sprains are the most common injury to the ankle joint, affecting up to 2 million people and approximately 53 per 10,000 individuals per year. 1,2 Ankle sprains are common in younger and active individuals. 3-8 Certain sports and work activities may result in an even higher incidence and risk for injury. 9-15 Ankle sprains are a clinically important problem because they result in a substantial number of missed work days 8 and participation in sports activity, 3,5 as well as lead to potential early arthritic changes in the talocrural joint. 16 The prognosis for functional recovery following ankle sprain typically includes a rapid clinical improvement within the first two weeks after injury. 17 However, a series of recent studies indicate a subgroup of individuals appears predisposed to continued pain, functional deficits, and prolonged risk for additional reinjury between 6 weeks and 3 years post injury. 17-25 The prolonged disability associated with ankle sprains represents the possibility of increased direct and indirect health care costs associated with ankle sprains, and may be reduced through identification of optimal approaches to clinical management. One reason for continued pain and elevated risk for reinjury may be limited ankle joint mobility, which may occur as either a cause or consequence of ankle sprain. Limited ankle dorsiflexion has been documented as a major short-term sequel to ankle sprain. 26,27 In addition, several studies have identified limited talocrural joint dorsiflexion range of motion (DF ROM) as an important predisposing factor to ankle sprains. 28-30 Limited ankle DF ROM will position the talocrural joint in plantar flexion during weight bearing activities. This position is notable because the most common mechanism of injury for ankle sprains involves plantar flex-ion and inversion of the ankle and foot. The injury mechanism places excessive load on the anterior talofibular ligament (ATFL). With failure of ATFL, secondary restraint to inversion occurs by way of the calcaneo-fibular and posterior talofibular ligaments, placing them at similar risk for injury. Thus, limited ankle DF ROM may result in injury and consequent structural and functional compromise of the ankle lateral collateral ligaments. Physical therapists use mobilization and manipulation to improve ankle DF ROM following ankle sprains. Despite the intuitive appeal of applying these procedures to promote parallel improvements in talocrural DF ROM and functioning in individuals following ankle sprains, this notion has been the focus of relatively few prospective studies. 31 Pellow and Brantingham 32 were among the first to report reduced pain and improved function in individuals with ankle sprains receiving an ankle mortise distraction technique. Whitman and colleagues 33 reported rapid functional improvement after talocrural manipulation in a competitive volleyball player with a mild unilateral

Within-day test-retest reliability of transcranial magnetic stimulation measurements of corticomotor excitability for gastrocnemius and tibialis anterior muscles

Background: Manual therapy interventions targeting the talocrural joint can improve gait and balance functions in individuals following ankle sprains. Less is known about the underlying mechanisms of functional improvements after manual therapy. One hypothesis involves change in corticomotor excitability (CE) following manual therapy procedures. Transcranial magnetic stimulation (TMS) is a brain imaging method that could provide important information regarding potential changes in CE associated with manual therapy techniques applied to the talocrural joint. However, within-day reliability of TMS to measure CE must first be established in order to measure CE changes associated with manual therapy procedures. Objective: To determine the within-day test-retest reliability of TMS CE measures for gastrocnemius (GAS) and tibialis anterior (TA) for use in test-retest designs assessing corticomotor excitability in manual therapy and exercise studies. Method: TMS measures, including motor evoked potential (MEP) amplitude and cortical silent period (CSP), were completed twice on the same day under resting and active conditions in n = 6 nondisabled participants. The absolute reliability (coefficient of variation), relative reliability (intraclass correlation coefficient), standard error of measures, and minimal detectable change outside the 95% confidence interval were calculated for both GAS and TA muscles in each experimental condition. Results: There were no statistically significant differences between the first and second TMS measurements. TMS measurements for GAS and TA demonstrated good absolute and relative test-retest reliability under the active condition, but not the resting condition. Discussion: TMS under the active condition can be reliably used to assess CE even in postural muscles with a small cortical representation area, such as GAS

Relationships Among Disease, Social Support, and Perceived Health: A Lifespan Approach

We examined the relationship between the cumulative presence of major disease (cancer, stroke, diabetes, heart disease, and hypertension), social support, and self‐reported general and emotional well‐being in a community representative sample of predominantly White and African American respondents (N = 1349). Across all ages, greater presence of disease predicted poorer reported general health, and predicted lower emotional well‐being for respondents 40 and above. In contrast, social support predicted better‐reported general and emotional well‐being. We predicted that different types of social support (blood relatives, children, friends, community members) would be relatively more important for health in different age groups based on a lifespan or life stage model. This hypothesis was supported; across all ages, social support was related to better reported general and emotional health, but sources of support differed by age. Broadly, those in younger age groups tended to list familial members as their strongest sources of support, whereas older group members listed their friends and community members. As a whole, social support mediated the effect of disease on reported well‐being, however, moderated mediation by type of support was not significant. The results are consistent with a lifespan approach to changing social ties throughout the life course.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116357/1/ajcp9758.pd

First sequence-confirmed case of infection with the new influenza A(H1N1) strain in Germany

Here, we report on the first sequence-confirmed case of infection with the new influenza A(H1N1) virus in Germany. Two direct contacts of the patient were laboratory-confirmed as cases and demonstrate a chain of direct human-to-human transmission

Enhancing Parenting Skills Among Nonresident African American Fathers as a Strategy for Preventing Youth Risky Behaviors

This study evaluated the effectiveness of a theoretically based, culturally specific family intervention designed to prevent youth risky behaviors by influencing the parenting attitudes and behaviors of nonresident African American fathers and the parent–child interactions, intentions to avoid violence, and aggressive behaviors of their preadolescent sons. A sample of 158 intervention and 129 comparison group families participated. ANCOVA results indicated that the intervention was promising for enhancing parental monitoring, communication about sex, intentions to communicate, race‐related socialization practices, and parenting skills satisfaction among fathers. The intervention was also beneficial for sons who reported more monitoring by their fathers, improved communication about sex, and increased intentions to avoid violence. The intervention was not effective in reducing aggressive behaviors among sons. Findings are discussed from a family support perspective, including the need to involve nonresident African American fathers in youth risky behavior prevention efforts.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116964/1/ajcp9290.pd

Examining Long‐Term Effects Of An Infant Mental Health Home‐Based Early Head Start Program On Family Strengths And Resilience

Infant Mental Health based interventions aim to promote the healthy development of infants and toddlers through promoting healthy family functioning to foster supportive relationships between the young child and his or her important caregivers. This study examined impacts of an Infant Mental Health home‐based Early Head Start (IMH‐HB EHS) program on family functioning. The sample includes 152 low‐income families in the Midwestern United States, expectant or parenting a child younger than 1 year of age, who were randomly assigned to receive IMH‐HB EHS services (n = 75) or to a comparison condition (n = 77). Mothers who received IMH‐HB EHS services reported healthier psychological and family functioning, outcomes that are consistent with the IMH focus, when their children were between the ages of 3 and 7 years of age. Specifically, mothers in the IMH‐HB EHS group reported healthier family functioning and relationships, better coping skills needed to advocate for their families, and less stress in the parenting role versus those in the comparison condition. The study also examined support seeking coping, some of which changed differently over time based on program group assignment. Overall, findings suggest that the gains families achieve from participating in IMH‐HB EHS services are maintained after services cease.RESUMENLa meta de las intervenciones con base en la salud mental infantil es promover el desarrollo sano de infantes y bebés por medio de promover un funcionamiento familiar sano para adoptar relaciones de apoyo entre el pequeño niño y sus importantes cuidadores. Este estudio examinó el impacto que sobre el funcionamiento familiar tiene un programa “Early Head Start” de salud mental infantil con base en casa (IMH‐HB EHS). El grupo muestra lo componen 152 familias de bajos recursos del Medio Oeste de Estados Unidos, en espera de o ya criando a un niño menor de un año de edad, que fueron asignadas al azar para recibir los servicios de IMH‐HB EHS (n=75) o a una condición comparativa (n=77). Las madres que recibieron los servicios de IMH‐HB EHS reportaron un funcionamiento sicológico y familiar más saludable, resultados que son consistentes con el enfoque de IMH, cuando sus niños tenían entre 3 y 7 años de edad. Específicamente, las madres en el grupo IMH‐HB EHS reportaron un funcionamiento y relaciones familiares más saludables, mejores habilidades para arreglárselas que eran necesarias para abogar por sus familias, así como menos estrés en el papel de crianza al ser comparadas con aquellas madres en la condición comparativa. El estudio también examinó la manera de arreglárselas buscando apoyo, algunas de las cuales cambiaron diferentemente a través del tiempo con base en las asignaciones de grupo del programa. En general, los resultados sugieren que los aspectos positivos que las familias alcanzan como resultado de participar en los servicios de IMH‐HB EHS se mantienen después que los servicios terminan.RÉSUMÉLes interventions fondées sur la santé mentale ont pour but de promouvoir le développement sain des nourrissons et des jeunes enfants en promouvant le fonctionnement saind'une famille afin de favoriser des relations de soutien entre le jeune enfant et ceux qui s'occupent d'elle ou de lui. Cette étude a examiné les impacts d'un programme américain de Early Head Start focalisé sur la santé mentale du nourrisson (abrégé IMH‐HB EHS) sur le fonctionnement de la famille. L’échantillon a compris 152 familles de milieu défavorisé de la région centre des Etats‐Unis, attendant un enfant ou s'occupant d'un enfant de moins d'un an, a qui on a assigné au hasard les services IMH‐HB EHS (n=75) ou une condition de comparaison (n=77). Les mères ayant reçu les services IMH‐HB EHS ont fait état d'un meilleur fonctionnement psychologique et familial, des résultats qui correspondent à l'objectif de santé mentale du nourrisson, lorsque leurs enfants avaient entre 3 et 7 ans. Plus spécifiquement, les mères du groupe IMH‐HB EHS ont fait état d'un meilleur fonctionnement familial et de meilleurs relations familiales, de meilleures capacités à s'adapter nécessaires afin de se porter les avocates de leurs familles, et de moins de stress de parentage comparé à celles du groupe de comparaison. L’étude a aussi examiné l'adaptation liée à la quête de soutien, qui a en partie changé différemment au fil du temps, en fonction du groupe de placement. Au bout du compte les résultats suggèrent que les gains obtenus par les familles comme résultat de la participation aux services du IMH‐HB EHS se maintiennent après que les services cessent.ZUSAMMENFASSUNGInterventionen, die auf der mentalen Gesundheit von Säuglingen basieren, zielen darauf ab, die gesunde Entwicklung von Säuglingen und Kleinkindern zu verbessern, indem ein gesundes familiäres Funktionieren gefördert wird, um unterstützende Beziehungen zwischen dem Kleinkind und ihren/seinen wichtigsten Bezugspersonen zu begünstigen. Diese Studie untersuchte die Effekte eines Early Head Start‐Hausbesuchs‐Programms (IMH‐HB EHS) auf das familiäre Funktionieren. Die Stichprobe umfasst 152 Familien mit niedrigem Einkommen aus dem Mittleren Westen der USA. Es handelt sich bei der Stichprobe um werdende Eltern oder Eltern mit einem Kind unter einem Jahr, die randomisiert einer Dienstleistung zugewiesen wurden: zum IMH‐HB EHS‐Programm (n = 75) oder zu einer Vergleichsbedingung (n = 77). Mütter, die das IMH‐HB EHS‐Programm erhielten, berichteten von gesünderem psychologischem und familiärem Funktionieren, wenn ihre Kinder im Alter zwischen 3 und 7 Jahren waren. Dies sind Ergebnisse, die mit dem IMH Fokus übereinstimmen. Im Speziellen berichteten Mütter, die in der IMH‐HB EHS‐Gruppe waren, von gesünderem familiären Funktionieren und familiären Beziehungen, besseren Bewältigungsstrategien, um für ihre Familien einzustehen und von weniger Stress in der Elternrolle verglichen mit den Müttern der Vergleichsbedingung. Die Studie untersuchte auch unterstützungssuchende Bewältigungsstrategien, von denen sich einige basierend auf der Gruppenzugehörigkeit im Laufe der Zeit in unterschiedlicher Weise veränderten. Insgesamt deuten die Ergebnisse darauf hin, dass die Gewinne, die die Familien infolge der Teilnahme am IMH‐HB EHS‐Programm erzielten, nach Ende des Programms aufrechterhalten werden.抄録乳幼児精神保健に基づく介入は、幼い子どもとその重要な養育者との間の支持的な関係性を育てるという健康な家族機能の促進を通して、乳幼児の健康な発達を促進することを目的としている。この研究は、乳幼児精神保健在宅早期ヘッドスタートInfant Mental Health home‐based Early Head Start (IMH‐HB EHS)プログラムが、家族機能に与える影響を調査した。対象はアメリカ合衆国中西部の妊娠中か1歳以下の子どもを育てている152の低所得家族で、IMH‐HB EHSサービスを受ける(n=75)か、比較の条件か(n=77)に、ランダムに割り当てられた。IMH‐HB EHSサービスを受けた母親は、子どもが3歳から7歳の間に、より健康的な心理機能および家族機能を報告した。これはIMHの焦点と一致している結果だった。特に、IMH‐HB EHS群の母親は、比較条件の母親と比べ、より健康な家族機能と関係性、家族を擁護するのに必要なよりよい対処機能、そして親役割にストレスが少ないことを報告した。研究はまた、支援を求める対処についても調査した。その一部はプログラム群への割り当てに基づいて時間経過により異なって変化していた。全体として、IMH‐HB EHSサービスに参加した結果として家族が達成し獲得したものは、サービスが終了した後も、維持されている。摘要以幼兒心理健康為基礎的介入旨在通過健康的家庭運作去培養小童與其重要看護者間的支持性關係, 以此促進幼兒和學步兒的健康發展。本文探討一個幼兒心理健康家訪早期搶步計畫 (IMH‐HB‐EHS) 對家庭運作的影響。樣本包括一百五十二個在美國中西部低入息的家庭。這些家庭正待產或在養育一個少於一歲的小孩。參與家庭被隨機分派到接受IMH‐HB‐EHS服務 (n=75) 或一個比較環境 (n=77)。有接受IMH‐HB‐EHS服務的母親報告在孩兒三至七歲間有較健康的心理和家庭運作, 這結果與IMH的焦點相附合。具體來說, 在IMH‐HB‐EHS組的母親較在比較環境組的母親報告有健康些的家庭運作和關係, 有好些的因應技巧為家庭作鼓吹, 及在親職角色中有少些壓力。本文亦探討尋求支持的因應, 發現這會根據組別分派而有不同的隨時間改變。總體而言, 探討結果顯示家庭從參與IMH‐HB‐EHS服務所得的收益在服務停止後仍會維持。Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112230/1/imhj21518.pd

Rate enhancement in collisions of sulfuric acid molecules due to long-range intermolecular forces

Collisions of molecules and clusters play a key role in determining the rate of atmospheric new particle formation and growth. Traditionally the statistics of these collisions are taken from kinetic gas theory assuming spherical noninteracting particles, which may significantly underestimate the collision coefficients for most atmospherically relevant molecules. Such systematic errors in predicted new particle formation rates will also affect large-scale climate models. We studied the statistics of collisions of sulfuric acid molecules in a vacuum using atomistic molecular dynamics simulations. We found that the effective collision cross section of the H2SO4 molecule, as described by an optimized potentials for liquid simulation (OPLS). OPLS all-atom force field, is significantly larger than the hard-sphere diameter assigned to the molecule based on the liquid density of sulfuric acid. As a consequence, the actual collision coefficient is enhanced by a factor of 2.2 at 300 K compared with kinetic gas theory. This enhancement factor obtained from atomistic simulation is consistent with the discrepancy observed between experimental formation rates of clusters containing sulfuric acid and calculated formation rates using hard-sphere kinetics. We find reasonable agreement with an enhancement factor calculated from the Langevin model of capture, based on the attractive part of the atomistic intermolecular potential of mean force.Peer reviewe