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This study examined differences in friendship quality between children with traumatic brain injury (TBI) and orthopedic injury (OI) and behavioral outcomes for children from both groups. Participants were 41 children with TBI and 43 children with OI (M age=10.4). Data were collected using peer- and teacher-reported measures of participants’ social adjustment and parent-reported measures of children’s post-injury behaviors. Participants and their mutually nominated best friends also completed a measure of the quality of their friendships. Children with TBI reported significantly more support and satisfaction in their friendships than children with OI. Children with TBI and their mutual best friend were more similar in their reports of friendship quality compared to children with OI and their mutual best friends. Additionally, for children with TBI who were rejected by peers, friendship support buffered against maladaptive psychosocial outcomes, and predicted skills related to social competence. Friendship satisfaction was related to higher teacher ratings of social skills for the TBI group only. Positive and supportive friendships play an important role for children with TBI, especially for those not accepted by peers. Such friendships may protect children with TBI who are rejected against maladaptive psychosocial outcomes, and promote skills related to social competence. (JINS, 2014, 21, 1–10)
Various adaptation strategies are available that will minimize or negate predicted climate change-related increases in yield loss from phoma stem canker in UK winter oilseed rape (OSR) production. A number of forecasts for OSR yield, national production and subsequent economic values are presented, providing estimates of impacts on both yield and value for different levels of adaptation. Under future climate change scenarios, there will be increasing pressure to maintain yields at current levels. Losses can be minimized in the short term (up to the 2020s) with a ‘low’-adaptation strategy, which essentially requires some farmer-led changes towards best management practices. However, the predicted impacts of climate change can be negated and, in most cases, improved upon, with ‘high’-adaptation strategies. This requires increased funding from both the public and private sectors and more directed efforts at adaptation from the producer. Most literature on adaptation to climate change has had a conceptual focus with little quantification of impacts. It is argued that quantifying the impacts of adaptation is essential to provide clearer information to guide policy and industry approaches to future climate change risk.
We consider the steady levitation of a rigid plate on a thin air cushion with prescribed injection velocity. This injection velocity is assumed to be much larger than that in a conventional Prandtl boundary layer, so that inertial effects dominate. After applying the classical ‘blowhard’ theory of Cole & Aroesty (1968) to the two-dimensional version of the problem, it is shown that in three dimensions the flow may be foliated into streamline surfaces using Lagrangian variables. An example is given of how this may be exploited to solve the three-dimensional problem when the injection pressure distribution is known.
A three-phase ensemble-averaged model is developed for the flow of water and air through
a deformable porous matrix. The model predicts a separation of the flow into saturated
and unsaturated regions. The model is closed by proposing an experimentally-motivated
heuristic elastic law which allows large-strain nonlinear behaviour to be treated in a relatively
straightforward manner. The equations are applied to flow in the ‘nip’ area of a roll press
machine whose function is to squeeze water out of wet paper as part of the manufacturing
process. By exploiting the thin-layer limit suggested by the geometry of the nip, the problem
is reduced to a nonlinear convection-diffusion equation with one free boundary. A numerical
method is proposed for determining the flow and sample simulations are presented.
The development of apothecia of Pyrenopeziza brassicae (anamorph Cylindrosporium concentricum) on oilseed rape debris and compost
malt agar was observed by scanning electron and light microscopy. On oilseed rape debris, apothecia developed directly beneath the
epidermis as small globular structures of dense mycelium, which protruded through the epidermis as they increased in size. The
apices of erumpent immature apothecia then developed small ostiolar openings which increased in diameter to expose the hymenia
of mature apothecia containing dome-shaped asci interspersed with filiform paraphyses. On compost malt agar, hyphae of one
mating type grew towards hyphae of the opposite mating type 3–4 d after inoculation of conidia onto agar surfaces. The subsequent
development of apothecia on compost malt agar was similar to that on oilseed rape debris.
This book is intended as a text for a first-year physical-chemistry or chemical-physics graduate course in quantum mechanics. Emphasis is placed on a rigorous mathematical presentation of the principles of quantum mechanics with applications serving as illustrations of the basic theory. The material is normally covered in the first semester of a two-term sequence and is based on the graduate course that I have taught from time to time at the University of Pennsylvania. The book may also be used for independent study and as a reference throughout and beyond the student's academic program.
The first two chapters serve as an introduction to quantum theory. It is assumed that the student has already been exposed to elementary quantum mechanics and to the historical events that led to its development in an undergraduate physical chemistry course or in a course on atomic physics. Accordingly, the historical development of quantum theory is not covered. To serve as a rationale for the postulates of quantum theory, Chapter 1 discusses wave motion and wave packets and then relates particle motion to wave motion. In Chapter 2 the time-dependent and time-independent Schrödinger equations are introduced along with a discussion of wave functions for particles in a potential field. Some instructors may wish to omit the first or both of these chapters or to present abbreviated versions.
Chapter 3 is the heart of the book. It presents the postulates of quantum mechanics and the mathematics required for understanding and applying the postulates.
The postulates 1 to 6 of quantum mechanics as stated in Sections 3.7 and 7.2 apply to multi-particle systems provided that each of the particles is distinguishable from the others. For example, the nucleus and the electron in a hydrogen-like atom are readily distinguishable by their differing masses and charges. When a system contains two or more identical particles, however, postulates 1 to 6 are not sufficient to predict the properties of the system. These postulates must be augmented by an additional postulate. This chapter introduces this new postulate and discusses its consequences.
Permutations of identical particles
Particles are identical if they cannot be distinguished one from another by any intrinsic property, such as mass, charge, or spin. There does not exist, in fact and in principle, any experimental procedure which can identify any one of the particles. In classical mechanics, even though all particles in the system may have the same intrinsic properties, each may be identified, at least in principle, by its precise trajectory as governed by Newton's laws of motion. This identification is not possible in quantum theory because each particle does not possess a trajectory; instead, the wave function gives the probability density for finding the particle at each point in space. When a particle is found to be in some small region, there is no way of determining either theoretically or experimentally which particle it is.
A molecule is composed of positively charged nuclei surrounded by electrons. The stability of a molecule is due to a balance among the mutual repulsions of nuclear pairs, attractions of nuclear–electron pairs, and repulsions of electron pairs as modified by the interactions of their spins. Both the nuclei and the electrons are in constant motion relative to the center of mass of the molecule. However, the nuclear masses are much greater than the electronic mass and, as a result, the nuclei move much more slowly than the electrons. Thus, the basic molecular structure is a stable framework of nuclei undergoing rotational and vibrational motions surrounded by a cloud of electrons described by the electronic probability density.
In this chapter we present in detail the separation of the nuclear and electronic motions, the nuclear motion within a molecule, and the coupling between nuclear and electronic motion.
Nuclear structure and motion
We consider a molecule with Ω nuclei, each with atomic number Zα and mass Mα(α = 1, 2, …, Ω), and N electrons, each of mass me. We denote by Q the set of all nuclear coordinates and by r the set of all electronic coordinates. The positions of the nuclei and electrons are specified relative to an external set of coordinate axes which are fixed in space.