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Multisystem, multi-level interventions are required to enable resilient, nurturing environments for children facing adversity. This study assesses parenting behavior associated with participation in a community-based, adapted microfinance program, and mediated by program-affiliated social capital, maternal depression and self-esteem among Kenyan women. Participants in the intervention, Kuja Pamoja kwa Jamii (KPJ, Swahili for “Come Together to Belong”), gather weekly to engage in trainings and group-based microfinance. Groups selected for the study had participated in the program for 0–15 months at the time of the first interview. Women (n = 400) completed surveys in June 2018 and June 2019. Measures included duration of program exposure, group-affiliated social capital (i.e. trust, belonging, cohesion, and expectation of mutual benefit), depression, self-esteem, and conflict tactics. We used regression analyses and generalized structural equation models to explore associations between program exposure, social capital, psychosocial variables and child maltreatment. Each standard deviation increase in duration of program exposure decreased odds of child physical abuse by 40% and child neglect by 35%. Each standard deviation in the social capital index predicted a significant reduction in odds of child physical abuse (aOR: 0.67), and child neglect (aOR: 0.71). Self-esteem and depression fully mediated observed associations between social capital and child maltreatment. Findings recommend further investigation of the potential for adapted microfinance programs to deliver parenting interventions, improve mental health and foster resilience-enabling social capital. A randomized control trial is required to validate the potential of the assessed intervention to improve parenting behaviors and supportive social conditions.

Hundreds of millions of people suffer anxiety disorders globally, demonstrating need for scalable and effective interventions. Adverse childhood experiences contribute to this mental health burden. The stress-buffering hypothesis, which posits social factors moderate prior adversity and subsequent mental health outcomes, provides one theoretical avenue to consider observations that group-based microfinance programs improve social capital. We investigate associations between adverse childhood experiences, generalized anxiety among adults and social capital associated with participation in a group-based microfinance program in rural Kenya. Adult participants (n = 400 women) responded to standardized measures of childhood adversity in June 2018, group-affiliated social capital and generalized anxiety in June 2019. Cumulative adverse childhood experiences predicted higher anxiety, which was statistically moderated by the presence of group-affiliated interpersonal trust. This study is the first to find social capital associated with participation in a group-based microfinance program statistically moderates expected associations between adverse childhood experiences and adult generalized anxiety. Future study should be conducted using a cluster-randomized control design to further assess the potential of this intervention method to ameliorate associations between past adversity and current mental health.

An electrical conductivity tensor is used in a 1.5D magnetohydrodynamic (MHD) simulation to describe how MHD shock waves may form, propagate, and heat the photosphere and chromosphere by compression and resistive dissipation. The spatial resolution is 1 km. A train of six shock waves is generated by a sinusoidal magnetic field driver in the photosphere with a period T = 30 s, mean of 500 G, and variation of 250 G. The duration of the simulation is 200 s. Waves generated in the photosphere evolve into shock waves at a height z ~ 375 km above the photosphere. The transition of the atmosphere from weakly to strongly magnetized with increasing height causes the Pedersen resistivity η P to increase to ~2000 times the Spitzer resistivity. This transition occurs over a height range of a few hundred kilometers near the temperature minimum of the initial state at z ~ 500 km. The initial state is a model atmosphere derived by Fontenla et al., plus a background magnetic field. The increase in η P is associated with an increase in the resistive heating rate Q. Shock layer thicknesses are ~10-20 km. They are nonzero due to the presence of resistive dissipation, so magnetization-induced resistivity plays a role in determining shock structure, and hence the compressive heating rate Qc . At t = 200 s the solution has the following properties. Within shock layers, Q maximum ~ 1.4-7 erg cm–3 s–1, and Q c,maximum ~ 10-103 Q maximum. Between shock waves, and at some points within shock layers, Qc < 0, indicating cooling by rarefaction. The integrals of Q and Qc over the shock wave train are F ~ 4.6 × 106 erg cm–2 s–1 and Fc ~ 1.24 × 109 erg cm–2 s–1. A method based on the thermal, mechanical, and electromagnetic energy conservation equations is presented for checking the accuracy of the numerical solution, and gaining insight into energy flow and transformation. The method can be applied to higher dimensional simulations. It is suggested that observations be performed to map out the transition region across which the transition from weakly ionized, weakly magnetized plasma to weakly ionized, strongly magnetized plasma occurs, and to correlate it with net radiative loss.

Murine embryonic stem (mES) cells are self-renewing pluripotent cells that bear the capacity to differentiate into ectoderm-, endoderm-, and mesoderm-derived tissues. In suspension culture, embryonic stem (ES) cells grow into spherical embryoid bodies (EBs) and are useful for the study of specific gene products in the development and function of various tissue types. Osteoclasts are hematopoietic stem cell-derived cells that participate in bone turnover by secreting resorptive molecules such as hydrochloric acid and acidic proteases, which degrade the bone extracellular matrix. Aberrant osteoclast function leads to dysplastic, erosive, and sclerosing bone diseases. Previous studies have reported the derivation of osteoclasts from mES cells; however, most of these protocols require coculture with stromal cell lines. We describe two simplified, novel methods of stromal cell-independent ES cell-derived osteoclast development.

A 1.5-dimensional, time-dependent magnetohydrodynamic (MHD) model that includes an energy equation and anisotropic electrical conductivity tensor for a variably ionized, multispecies plasma is presented. The model includes an algorithm that reduces the numerical dissipation rate far below the dissipation rate determined by the conductivity tensor. This is necessary for accurate calculation of resistive heating rates. The model is used to simulate the propagation of Alfven waves launched near the base of the middle chromosphere. The background state is the FAL CM equilibrium with a vertical magnetic field. The initial magnetic energy of a wave is almost completely damped out in the chromosphere by the time the disturbance propagates a distance of one wavelength. The energy is converted mainly into thermal energy. The remainder is converted into bulk flow kinetic energy and a Poynting flux with nonzero divergence. The thermal energy is generated almost entirely by Pedersen current dissipation. The corresponding heating rates are close to the FAL CM values near the base of the middle chromosphere. Dynamo action is observed. The damping of a continuously driven Alfven wave train is also simulated, yielding results similar to those of the single wave cases. It is the strong magnetization and weak ionization of the chromosphere that allows for strong heating by Pedersen current dissipation. This distinguishes the chromosphere from the weakly magnetized and weakly ionized photosphere, and the strongly magnetized and strongly ionized corona where Pedersen current dissipation is not significant on the length and timescales simulated.

A magnetohydrodynamic (MHD) model of an electron-ion, collision-dominated plasma that includes the electrical conductivity and thermoelectric tensors in Ohm's law is used to generate current sheet solutions in parameter ranges that correspond to those of the solar transition region and lower corona. The model contains a prescribed sheared magnetic field with a characteristic length scale L. The characteristic sheet width is 2L, but it is found that the temperature has transition region or coronal values only within a diffusion region (DR) with a width several orders of magnitude smaller than 2L. The heating rate per unit mass and flow speed in the DR are orders of magnitude larger, and the density is orders of magnitude smaller than in the surrounding plasma. The heating rate per unit volume is a maximum in the DR and falls off steadily outside the DR. The Joule heating rate and current density each consist of a conduction component driven by the center-of-mass electric field and a thermoelectric component driven by the temperature gradient. It is found that these components largely cancel, leading to a total heating rate and current density orders of magnitude smaller than either of their components. This suggests that thermoelectric current drive is important in determining current sheet structure. The center-of-mass electric field that provides the energy to maintain the plasma in a steady state is almost entirely the convection electric field. The electron magnetization Me is the product of the electron cyclotron frequency and the electron-ion collision time. Nonzero values of Me cause the conductivity and thermoelectric tensors to be anisotropic. It is found that the large values of Me that occur in the DR increase the heating rates per unit volume and mass by several orders of magnitude and can change the sign of the heating rate per unit mass from negative to positive, corresponding to a change from a cooling process to a heating process. This suggests that electron magnetization, and hence anisotropic transport, is a major factor in current sheet heating.

Three points and research directions are discussed: The outstanding problem of identifying the mechanisms of solar atmospheric heating and wind acceleration can be solved only by combining quantitative models that include realistic descriptions of relevant transport processes with observational constraints on the inputs and outputs of these models. Most solar atmospheric heating, with the possible exception of flares, takes place in the chromosphere, emphasizing the importance of identifying the mechanisms of chromospheric heating, which may be important for understanding coronal heating and wind acceleration. Recent modeling leads to the conclusion that the onset of proton magnetization with increasing height in thin magnetic flux tubes triggers the onset of chromospheric network heating by resistive dissipation of Pedersen currents driven by the convection electric field of slow, longitudinal magnetoacoustic waves.

A mechanism for chromospheric network heating and a necessary and sufficient condition for its onset are presented. The heating mechanism consists of resistive dissipation of proton Pedersen currents, which flow orthogonal to the magnetic field in weakly ionized chromospheric plasma. The currents are driven by a convection electric field generated by velocity oscillations of linear, slow, longitudinal magnetoacoustic waves with frequencies ? 3.5 mHz in the lower chromosphere. The heating occurs in thin magnetic flux tubes and begins lower in the chromosphere in flux tubes with higher photospheric field strength. The lower chromosphere, which emits most of the net radiative loss in the network, is heated by flux tubes with photospheric field strengths ~700-1500 G. A typical field strength and core diameter for a flux tube in the lower chromosphere with a core heating rate of 107 ergs cm-2 s-1 are 170 G and 10 km. This core region is contained in a region with a diameter ~100 km in which the heating rate is an order of magnitude smaller. About N ~ 102 of these flux tubes distributed over the boundary region of a granule with a diameter ~103 km provide an average heating rate over the entire granule ~107 ergs cm-2 s-1. If the core heating rate is changed by a factor f, then N ~ f-1/2102. The condition for the onset of heating is that the ratio of the proton cyclotron frequency to the proton-hydrogen collision frequency equal unity. This ratio increases with height, and the condition is satisfied at a single height in a given flux tube. At this height, control of the proton dynamics begins to be dominated by the magnetic field rather than by collisions with hydrogen, and the anisotropic nature of the electrical conductivity begins to play a critical role in resistive dissipation. The protons become magnetized. Heating by dissipation of heavy ion and, to a lesser extent, proton Pedersen currents causes the temperature to start increasing. The heating increases hydrogen ionization. With increasing height, and hence proton magnetization, the Pedersen current density rapidly increases with hydrogen ionization via positive feedback, and the proton number density rapidly reaches and exceeds the heavy ion number density, resulting in an increase in heating rate by an order of magnitude over only 1 pressure scale height. During this process the protons rapidly dominate the Pedersen current. Heating by dissipation of magnetic field aligned currents is insignificant. Below the height in the atmosphere at which the onset condition is satisfied, any current orthogonal to the magnetic field must be primarily a Hall current, which is nondissipative. Heating by this mechanism must occur to some degree in the chromospheric network of all solar-type stars. It is proposed to be the dominant mechanism of chromospheric network heating, although viscous dissipation may also be important if the core heating rate is much larger than ~107 ergs cm-2 s-1 or if the linear MHD waves studied here evolve into shock waves with increasing height. Flux tubes in the quiet chromosphere are predicted to have two possible core diameters: ~10 km, corresponding to flux tubes in which network heating occurs, and ~104-105 km, perhaps corresponding to flux tubes in which active region heating might occur. The model has a singularity at the acoustic cutoff frequency, corresponding to periods near 3 minutes. Therefore, unless nonresistive damping mechanisms such as viscous dissipation and thermal conduction provide sufficiently strong damping, MHD oscillations with periods near 3 minutes in chromospheric magnetic flux tubes must be nonlinear.

The classical transport coefficients provide an accurate description of transport processes in collision-dominated plasmas. These transport coefficients are used in a cylindrically symmetric, electrically driven, steady-state magnetohydrodynamic (MHD) model with flow and an energy equation to study the effects of transport processes on MHD equilibria. The transport coefficients, which are functions of number density, temperature and magnetic field strength, are computed self-consistently as functions of radius R . The model has plasma-confining solutions characterized by the existence of an inner region of plasma with values of temperature, pressure and current density that are orders of magnitude larger than in the surrounding, outer region of plasma that extends outward to the boundary of the cylinder at R = a . The inner and outer regions are separated by a boundary layer that is an electric-dipole layer in which the relative charge separation is localized, and in which the radial electric field, temperature, pressure and axial current density vary rapidly. By analogy with laboratory fusion plasmas in confinement devices, the plasma in the inner region is confined plasma, and the plasma in the outer region is unconfined plasma. The solutions studied demonstrate that the thermoelectric current density, driven by the temperature gradient, can make the main contribution to the current density, and that the thermoelectric component of the electron heat flux, driven by an effective electric field, can make a large contribution to the total heat flux. These solutions also demonstrate that the electron pressure gradient and Hall terms in Ohm's law can make dominant contributions to the radial electric field. These results indicate that the common practice of neglecting thermoelectric effects and the Hall and electron pressure-gradient terms in Ohm's law is not always justified, and can lead to large errors. The model has three, intrinsic, universal values of β at which qualitative changes in the solutions occur. These values are universal in that they only depend on the ion charge number and the electron-to-ion mass ratio. The first such value of β (about 3.2% for a hydrogen plasma), when crossed, signals a change in sign of the radial gradient of the number density, and must be exceeded in order that a plasma-confining solution exist for a plasma with no flow. The second such value of β (about 10.4% for a hydrogen plasma), when crossed, signals a change in sign of the poloidal current density. Some of the solutions presented exhibit this current reversal. The third such value of β is about 2.67 for a hydrogen plasma. When β is greater than or equal to this value, the thermoelectric, effective electric-field-driven component of the electron heat flux cancels 50% or more of the temperature-gradient-driven ion heat flux. If appropriate boundary conditions are given on the axis R =0 of the cylinder, the equilibrium is uniquely determined. Analytical evidence is presented that, together with earlier work, strongly suggests that if appropriate boundary conditions are enforced at the outer boundary R = a then the equilibrium exhibits a bifurcation into two states, one of which exhibits plasma confinement and carries a larger axial current than the other state, which is close to global thermodynamic equilibrium, and so is not plasma-confining. Exact expressions for the two values of the axial current in the bifurcation are presented. Whether or not a bifurcation can occur is determined by the values of a critical electric field determined by the boundary conditions at R = a , and the constant driving electric field, which is specified. An exact expression for the critical electric field is presented. Although the ranges of the physical quantities computed by the model are a subset of those describing fusion plasmas in tokamaks, the model may be applied to any two-component, electron–ion, collision-dominated plasma for which the ion cyclotron frequency is much larger than the ion–ion Coulomb collision frequency, such as the plasma in magnetic flux tubes in the solar interior, photosphere, lower transition region, and possibly the upper transition region and lower corona.

The transition region (TR) is assumed to be a collision-dominated plasma. The dissipation and transport of energy in such a plasma is accurately described by the classical transport coefficients, which include the electrical and thermal conductivity, viscosity, and thermoelectric tensors. These tensors are anisotropic and are functions of local values of temperature, density, and magnetic field strength. The transport coefficients are valid for all magnetic field strengths and so may be used to study the physics of weakly as well as strongly magnetized regions of the TR. They may be used in an MHD model to obtain a self-consistent, realistic description of the TR. The physics of kinetic processes is included in the MHD model through the transport coefficients. As a first step in studying heating and cooling processes in the TR in a realistic, quantitative manner, a 1.5 dimensional, steady state MHD model with a specified temperature profile is developed. The momentum equation includes the inertial, pressure, magnetic, and gravitational forces. Ohm's law includes the exact expressions for the electrical conductivity and thermoelectric tensors. It is found that the contribution of the dissipation of large-scale electric currents to in situ heating of the TR is negligible, but that thermal energy flowing into the TR from the corona can provide the energy required to heat the TR. The possibility that significant in situ heating of the TR takes place through viscous dissipation or small-scale electric current dissipation such as may occur in current sheets or filaments is discussed, although these processes are not described by the model. The importance of thermoelectric and electron pressure gradient effects in Ohm's law, and in determining the electron heat flux, is demonstrated. Results of the model suggest that the force-free approximation is not valid over most of the TR. Justification for assuming that the TR is collision dominated is presented. In particular, a self-consistent calculation of the ratio of the electric field parallel to the magnetic field to the Dreicer electric field yields a value 10-3, which suggests that anomalous transport processes are not important. The necessity of using a realistic description of transport processes in modeling heating mechanisms in the solar atmosphere is stressed.

A magnetohydrodynamic model that includes a complete electrical conductivity tensor is used to estimate conditions for photospherically driven, linear, non-plane Alfvenic oscillations extending from the photosphere to the lower corona to drive a chromospheric heating rate due to Pedersen current dissipation that is comparable to the net chromospheric net radiative loss of $\sim 10^7$ ergs-cm$^{-2}$-sec$^{-1}$. The heating rates due to electron current dissipation in the photosphere and corona are also computed. The wave amplitudes are computed self-consistently as functions of an inhomogeneous background (BG) atmosphere. The effects of the conductivity tensor are resolved numerically using a resolution of 3.33 m. The oscillations drive a chromospheric heating flux $F_{Ch} \sim 10^7 - 10^8$ ergs-cm$^{-2}$-sec$^{-1}$ at frequencies $\nu \sim 10^2 - 10^3$ mHz for BG magnetic field strengths $B \gtrsim 700$ G and magnetic field perturbation amplitudes $\sim 0.01 - 0.1$ $B$. The total resistive heating flux increases with $\nu$. Most heating occurs in the photosphere. Thermalization of Poynting flux in the photosphere due to electron current dissipation regulates the Poynting flux into the chromosphere, limiting $F_{Ch}$. $F_{Ch}$ initially increases with $\nu$, reaches a maximum, and then decreases with increasing $\nu$ due to increasing electron current dissipation in the photosphere. The resolution needed to resolve the oscillations increases from $\sim 10$ m in the photosphere to $\sim 10$ km in the upper chromosphere, and is proportional to $\nu^{-1/2}$. Estimates suggest that these oscillations are normal modes of photospheric flux tubes with diameters $\sim 10-20$ km, excited by magnetic reconnection in current sheets with thicknesses $\sim 0.1$ km., Comment: 55 pages, 19 figures

An MHD model of a Hydrogen plasma with flow, an energy equation, NLTE ionization and radiative cooling, and an Ohm's law with anisotropic electrical conduction and thermoelectric effects is used to self-consistently generate atmospheric layers over a $50$ km height range. A subset of these solutions contain current sheets, and have properties similar to those of the lower and middle chromosphere. The magnetic field profiles are found to be close to Harris sheet profiles, with maximum field strengths $\sim 25-150$ G. The radiative flux $F_R$ emitted by individual sheets is $\sim 4.9 \times 10^5 - 4.5 \times 10^6$ ergs-cm$^{-2}$-s$^{-1}$, to be compared with the observed chromospheric emission rate of $\sim 10^7$ ergs-cm$^{-2}$-s$^{-1}$. Essentially all emission is from regions with thicknesses $\sim 0.5 - 13$ km containing the neutral sheet. About half of $F_R$ comes from sub-regions with thicknesses 10 times smaller. A resolution $\lesssim 5-130$ m is needed to resolve the properties of the sheets. The sheets have total H densities $\sim 10^{13}-10^{15}$ cm$^{-3}$. The ionization fraction in the sheets is $\sim 2-20$ times larger, and the temperature is $\sim 2000-3000$ K higher than in the surrounding plasma. The Joule heating flux $F_J$ exceeds $F_R$ by $\sim 4-34 \%$, the difference being balanced in the energy equation mainly by a negative compressive heating flux. Proton Pedersen current dissipation generates $\sim 62-77\%$ of the positive contribution to $F_J$. The remainder of this contribution is due to electron current dissipation near the neutral sheet where the plasma is weakly magnetized., Comment: 29 pages, 11 figures

The mathematical formulation of an iterative procedure for the numerical implementation of an ionosphere-magnetosphere (IM) anisotropic Ohm's law boundary condition is presented. The procedure may be used in global magnetohydrodynamic (MHD) simulations of the magnetosphere. The basic form of the boundary condition is well known, but a well-defined, simple, explicit method for implementing it in an MHD code has not been presented previously. The boundary condition relates the ionospheric electric field to the magnetic field-aligned current density driven through the ionosphere by the magnetospheric convection electric field, which is orthogonal to the magnetic field B, and maps down into the ionosphere along equipotential magnetic field lines. The source of this electric field is the flow of the solar wind orthogonal to B. The electric field and current density in the ionosphere are connected through an anisotropic conductivity tensor which involves the Hall, Pedersen, and parallel conductivities. Only the height-integrated Hall and Pedersen conductivities (conductances) appear in the final form of the boundary condition, and are assumed to be known functions of position on the spherical surface R=R1 representing the boundary between the ionosphere and magnetosphere. The implementation presented consists of an iterative mapping of the electrostatic potential ψ the gradient of which gives the electric field, and the field-aligned current density between the IM boundary at R=R1 and the inner boundary of an MHD code which is taken to be at R2>R1. Given the field-aligned current density on R=R2, as computed by the MHD simulation, it is mapped down to R=R1 where it is used to compute ψ by solving the equation that is the IM Ohm's law boundary condition. Then ψ is mapped out to R=R2, where it is used to update the electric field and the component of velocity perpendicular to B. The updated electric field and perpendicular velocity serve as new boundary conditions for the MHD simulation which is then used to compute a new field-aligned current density. This process is iterated at each time step. The required Hall and Pedersen conductances may be determined by any method of choice, and may be specified anew at each time step. In this sense the coupling between the ionosphere and magnetosphere may be taken into account in a self-consistent manner.

A cylindrically symmetric, electrically driven, dissipative, energy-conserving magnetohydrodynamic equilibrium model is considered. The high-magneticfield Braginskii ion thermal conductivity perpendicular to the local magnetic field and the complete electron resistivity tensor are included in an energy equation and in Ohm's law. The expressions for the resistivity tensor and thermal conductivity depend on number density, temperature, and the poloidal and axial (z-component) magnetic field, which are functions of radius that are obtained as part of the equilibrium solution. The model has plasma-confining solutions, by which is meant solutions characterized by the separation of the plasma into two concentric regions separated by a transition region that is an internal boundary layer. The inner region is the region of confined plasma, and the outer region is the region of unconfined plasma. The inner region has average values of temperature, pressure, and axial and poloidal current densities that are orders of magnitude larger than in the outer region. The temperature, axial current density and pressure gradient vary rapidly by orders of magnitude in the transition region. The number density, thermal conductivity and Dreicer electric field have a global minimum in the transition region, while the Hall resistivity, Alfvén speed, normalized charge separation, Debye length, (ωλ)ion and the radial electric field have global maxima in the transition region. As a result of the Hall and electron-pressure-gradient effects, the transition region is an electric dipole layer in which the normalized charge separation is localized and in which the radial electric field can be large. The model has an intrinsic value of β, about 13·3%, which must be exceeded in order that a plasma-confining solution exist. The model has an intrinsic length scale that, for plasma-confining solutions, is a measure of the thickness of the boundary-layer transition region. If appropriate boundary conditions are given at R = 0 then the equilibrium is uniquely determined. If appropriate boundary conditions are given at any outer boundary R = a then the equilibrium exhibits a bifurcation into two states, one of which exhibits plasma confinement and carries a larger axial current than the other, which is almost homogeneous and cannot confine a plasma. Exact expressions for the two values of the axial current in the bifurcation are derived. If the boundary conditions are given at R = a then a solution exists if and only if the constant driving electric field exceeds a critical value. An exact expression for this critical electric field is derived. It is conjectured that the bifurcation is associated with an electric-field-driven transition in a real plasma, between states with different rotation rates, energy dissipation rates and confinement properties. Such a transition may serve as a relatively simple example of the L—H mode transition observed in tokamaks.

A cylindrically symmetric, electrically driven, dissipative, energy-conserving magnetohydrodynamic equilibrium model is considered. The high-magnetic-field Braginskii electron electrical resistivity η parallel to a constant axial magnetic field B and ion thermal conductivity ĸ perpendicular to B are included in an energy equation and in Ohm's law. The expressions for η and ĸ depend on number density and temperature, which are functions of radius that are obtained as part of the equilibrium solution. The model has plasma-confining solutions, by which are meant solutions characterized by the separation of the plasma into two regions separated by a relatively thin transition region that is an internal boundary layer across which temperature and current density vary rapidly. The inner region has a temperature, pressure and current density that are much larger than in the outer region. The number density and thermal conductivity attain their minimum values in the transition region. The model has an intrinsic value of β, about 6.6%, which must be exceeded in order that a plasma-confining solution exist. The model has an intrinsic length scale, which, for plasma-confining solutions, is a measure of the thickness of the transition region separating the inner and outer regions of plasma. A larger class of transport coefficients is modelled by artificially changing η and ĸ by changing the constant coefficients ηO and ĸO that occur in their expressions. Increasing ĸO transforms a state that does not exhibit confinement into one that does, improves the confinement in a state that already exhibits it, and leads to an increase in ĸ in the confined region of plasma. The improvement in confinement consists in a decrease in the thickness of the transition region. Decreasing ηO subject to certain constraints, also transforms a state that does not exhibit confinement into one that does, improves the confinement in a state that already exhibits it, and leads to a decrease in η in the confined region of plasma. Increasing ηO up to a critical point increases the current, temperature, and volume of the confined region of plasma, and causes the thickness of the transition region to increase. If ηO is increased beyond the critical point, a plasma-confining state cannot exist. In all cases it is found that an increase in ĸ and a decrease in η in the confined region of plasma are associated with an improvement in the confinement properties of the equilibrium state. If the pressure and temperature are given on the cylinder wall, the equilibrium bifurcates when the electric field decreases below a critical value. The equilibrium can bifurcate into a state that exhibits confinement and a state that does not.

A magnetohydrodynamic model is used to determine conditions under which the Lorentz force accelerates plasma to type 2 spicule speeds in the chromosphere. The model generalizes a previous model to include a more realistic pre-spicule state, and the vertical viscous force. Two cases of acceleration under upper chromospheric conditions are considered. The magnetic field strength for these cases is ?12.5 and 25?G. Plasma is accelerated to terminal vertical speeds of 66 and 78?km?s?1 in 100?s, compared with 124 and 397?km?s?1 for the case of zero viscosity. The flows are localized within horizontal diameters ~80 and 50?km. The total thermal energy generated by viscous dissipation is ~10?times larger than that due to Joule dissipation, but the magnitude of the total cooling due to rarefaction is this energy. Compressive heating dominates during the early phase of acceleration. The maximum energy injected into the corona by type 2 spicules, defined as the energy flux in the upper chromosphere, may largely balance total coronal energy losses in quiet regions, possibly also in coronal holes, but not in active regions. It is proposed that magnetic flux emergence in intergranular regions drives type 2 spicules.

Purpose: The purpose of the study is to report the occurrence of optic neuropathy after stereotactic radiosurgery for perichiasmal tumors. Methods: Records of four patients with visual deterioration after stereotactic radiosurgery were reviewed, including clinical findings, neuroimaging results, and treatment methods. Results: Optic neuropathy developed 7 to 30 months after gamma knife radiosurgery. All patients experienced an abrupt change in visual function. Clinical findings indicated anterior visual pathway involvement. Patterns of field loss included nerve fiber bundle and homonymous hemianopic defects. Gadolinium-enhanced magnetic resonance imaging (MRI) showed swelling and enhancement of the affected portion of the visual apparatus in three patients. Systemic corticosteroids were administered in all patients and one partially recovered. One patient also received hyperbaric oxygen without improvement. Conclusions: Although rare, optic neuropathy may follow radiosurgery to lesions near the visual pathways. Careful dose planning guided by MRI with restriction of the maximal dose to the visual pathways to less than 8 Gy will likely reduce the incidence of this complication.

A 2.5D, time-dependent magnetohydrodynamic model is used to test the proposition that observed type II spicule velocities can be generated by a Lorentz force under chromospheric conditions. It is found that current densities localized on observed space and time scales of type II spicules and that generate maximum magnetic field strengths ?50 G can generate a Lorentz force that accelerates plasma to terminal velocities similar to those of type II spicules. Maximum vertical flow speeds are ~150-460?km?s?1, horizontally localized within ~2.5-10?km from the vertical axis of the spicule, and comparable to slow solar wind speeds, suggesting that significant solar wind acceleration occurs in type II spicules. Horizontal speeds are ~20 times smaller than vertical speeds. Terminal velocity is reached ~100 s after acceleration begins. The increase in the mechanical and thermal energy of the plasma during acceleration is (2-3) ? 1022?ergs. The radial component of the Lorentz force compresses the plasma during the acceleration process by factors as large as ~100. The Joule heating flux generated during this process is essentially due to proton Pedersen current dissipation and can be ~0.1-3.7 times the heating flux of ~106?ergs?cm?2?s?1 associated with middle-upper chromospheric emission. About 84%-94% of the magnetic energy that accelerates and heats the spicules is converted into bulk flow kinetic energy.

Purpose : A multi-institutional experience in radiosurgery for solitary brain metastases was combined to identify factors associated with safety, efficacy, tumor control, and survival. Materials and Methods : A review of 116 patients with solitary brain metastases who underwent gamma knife stereotactic radiosurgery at five institutions was performed. The median follow-up was 7 months following radiosurgery and 12 months following diagnosis. Minimum tumor doses varied from 8–30 Gy (mean, 17.5 Gy). Forty-five patients failed prior radiotherapy and 71 had no prior brain irradiation. Fifty-one patients had radiosurgery alone and 65 underwent combined radiosurgery with fractionated large-field radiotherapy (mean dose, 33.8 Gy). Results : Median survival was 11 months after radiosurgery and 20 months after diagnosis. Follow-up documented local tumor control in 99 patients (85%), tumor recurrence in 17 (15%), and documented radiation necrosis in one (1%). The 2-year actuarial tumor control rate was 67 ± 8%. Tumor histology affected survival (better for breast cancer, p = .004) and local control (better for melanoma and renal cell, p = .0003) in multivariate analyses. Combined fractionated radiotherapy and radiosurgery improved local control (p = .0111), but not survival in multivariate testing. Conclusion : Radiosurgery is effective in controlling solitary brain metastases with low morbidity. Further study is needed to better define optimum treatment parameters for radiosurgery.

A Harris sheet magnetic field with maximum magnitude B 0 and length scale L is combined with the anisotropic electrical conductivity, viscosity, and thermoelectric tensors for an electron-proton plasma to define a magnetohydrodynamic model that determines the steady state of the plasma. The transport tensors are functions of temperature, density, and magnetic field strength, and are computed self-consistently as functions of position x normal to the current sheet. The flow velocity, magnetic field, and gravitational force lie along the z-axis. The plasma is supported against gravity by the viscous force. Analytic solutions are obtained for temperature, density, and velocity. They are valid over a broad range of temperature, density, and magnetic field strength, and so may be generally useful in astrophysical applications. Numerical examples of solutions in the parameter range of the solar atmosphere are presented. The objective is to compare Joule and viscous heating rates, determine the velocity shear that generates viscous forces that support the plasma and are self-consistent with a mean outward mass flux comparable to the solar wind mass flux, and compare the thermoelectric and conduction current contributions to the Joule heating rate. The ratio of the viscous to Joule heating rates per unit mass can exceed unity by orders of magnitude, and increases rapidly with L. The viscous heating rate can be concentrated outside the region where the current density is localized, corresponding to a resistively heated layer of plasma bounded by viscously heated plasma. The temperature gradient drives a thermoelectric current density that can have a magnitude greater than that of the electric-field-driven conduction current density, so thermoelectric effects are important in determining the Joule heating rate.

The Mie series solution for the scattered field of a sphere with an anisotropic impedance boundary condition (IBC) is derived along with the corresponding scattering cross section. Conditions on the impedance that ensure a unique solution for the scattered field are derived. The anisotropic IBC is derived for a material with an anisotropic electric permittivity and a large anisotropic conductivity. For the special case of an isotropic IBC, a method is presented for testing whether any given impedance leads to a unique solution for the scattered field, and it is shown that, for every incident wave frequency and mode number l, there are exactly two values of the impedance for which the scattered field is not unique.

A case of epidermoid tumor enveloping an aneurysm of the anterior communicating artery is reported. Four embryologically similar epithelial tumors of the central nervous system associated with intracranial aneurysms, all craniopharyngiomas, have previously been reported. Theories attempting to relate tumor and aneurysm are discussed. The incidence of aneurysm associated with tumor is difficult to estimate and may be no greater than the probability of their coincidence by chance alone.

The Hall effect is studied as a correction to ideal magnetohydrodynamics (MHD) in the context of how it affects the linear stability of the cylindrical pinch in the simple case of a static, homogeneous equilibrium state. The effects of compressibility and electron pressure are included. The presence of the electron pressure gives rise to an electric field tangent to the boundary of the plasma. This introduces an additional boundary condition in the case of a perfectly conducting plasma boundary. Imposing this boundary condition eliminates the wave solutions presented in this paper. With respect to large radial wavenumber, the accumulation point of the slow magnetoacoustic wave frequency spectrum is changed from its finite value in ideal MHD to infinity by the Hall effect. The Hall effect gives rise to linear waves that do not exist in ideal MHD. Specifically, the Hall effect induces azimuthally symmetric, compressible, Alfven‐type wave propagation. The frequency spectrum of these waves is discrete and infinite and is a singular perturbation of the incompressible Alfven wave spectrum in ideal MHD. These Alfven‐type waves do not exist if the plasma is incompressible or if H≡K⋅B=0, where K is the wave vector of the perturbation and B is the equilibrium magnetic field.

Forty female patients with pituitary adenomas were studied retrospectively to determine whether factors could be identified that would help predict outcome from operation. Twenty-five patients had a normal prolactin level (less than or equal to 30 ng/ml) during the early postoperative period (less than or equal to 3 months) and 15 patients had persistent disease (prolactin greater than 30 ng/ml). Nine of the 25 patients who initially had normal prolactin levels during the early postoperative period were found to have elevated prolactin levels during the late postoperative period (greater than 3 months). As has been shown previously, tumor size and preoperative prolactin levels were important factors in predicting surgical outcome. Patients with smaller (Hardy Grades I and II) tumors had significantly better outcome than those with larger (Hardy Grades III and IV) tumors. Patients with successful surgical outcomes had significantly lower preoperative prolactin values (204 ng/ml) than those with operative failures (524 ng/ml). In addition to the known factors, the patient's age at the time of operation, the length of amenorrhea, and the patient's growth hormone response to insulin hypoglycemia were newly identified as factors that helped predict surgical outcome. Patients who were less than or equal to 26 years of age and who had had amenorrhea for less than or equal to 6 years at the time of operation had significantly better surgical outcomes. Patients with normal growth hormone responses to stimulation testing had significantly better surgical outcomes than those with a blunted preoperative growth hormone response. The data suggest that prolactin-secreting pituitary tumors may cause a progressive disorder for which operative cure may be obtained only early in the disease.

I-cell disease (ICD), mucolipidosis II, is an autosomal recessive syndrome resulting from defective phosphorylation of acid hydrolases. The diagnosis is made in early childhood and in most cases death occurs by age 5 as a result of cardiorespiratory complications. Pathologic changes are limited to mesenchymal tissues. We treated two children with ICD who developed atlantoaxial dislocation and myelopathy following minor injuries. The first child developed cardiovascular instability with manipulation of the C1 ring at operation, necessitating removal of the arch of C1 and fusion from occiput to C2. The second child was quadriplegic following anatomic reduction of the C1–C2 dislocation at operation during which somatosensory evoked potentials (SSEPs) showed no deleterious change. The atlantoaxial joint is unstable in ICD due to an incompetent transverse ligament infiltrated by storage cells. A cartilaginous, rather than calcified, odontoid process may contribute to the instability. The intraoperative neural injury occurred during attempts to effect anatomical reduction of the chronically dislocated C1–C2 joints and could have resulted from inadvertent trauma to the vertebral arteries and subsequent infarction of the cord. The lack of change in the intraoperative SSEPs was probably due to relative sparing of the posterior columns during the cord injury. We recommend that children with ICD and atlantoaxial instability undergo closed reduction of any existing malalignment followed by posterior C1–C2 fusion as long as the operative risk is not prohibitive. If preopera-tive closed reduction is not readily feasible and the cord is severely compromised, the C1 arch should be removed and the occiput fused to C2. Forceful attempts at anatomical reduction of the chronically dislocated C1–C2 segments should be avoided.

Large pituitary tumors are still a common problem. Thirty consecutive patients underwent operative decompression and radiation therapy for large sellar and suprasellar tumors. They were studied prospectively in terms of their endocrine outcome. Ten of the patients had panhypopituitarism both before and after treatment. The other 20 patients had partial hormonal deficits prior to treatment. Ten (50%) of the 20 patients who had partial preoperative deficits went on to develop delayed onset of worsening in their endocrine function; 9 of the 10 developed panhypopituitarism, and 1 patient developed decreased thyroid function. The mean time from surgery until the onset of delayed worsening in endocrine function was 26.1 months. The mean age of those patients who developed delayed onset of worsening in pituitary function was significantly higher than that of those who did not develop further hormonal loss (40.5 ± 3.1 years versus 52.0 ± 4.1 years, P < 0.05). None of the 10 patients with delayed onset of worsening in pituitary function had anatomical evidence by computed tomographic scan of tumor recurrence. Delayed onset radiation effect is the most likely cause of the late onset of worsening in endocrine function.

We report a case of brain abscess complicating the use of a halo orthosis in the treatment of a cervical spine injury suffered during wrestling. Four previous brain abscesses complicating the use of halo orthoses have been reported. All cases of abscess have been associated with overlying infection at the site of pin insertion. Our case and at least one of those previously reported may have been related to tightening of the halo pins after placement. Serious spine injuries occur rarely in wrestlers and are associated with the use of illegal holds and maneuvers in which one athlete is thrown to the mat. The pathophysiology and radiographic appearance of a unilateral facet dislocation are reviewed.

Aspergillus species are second only to Cryptococcus neoformans as the most common cause of fungal infections of the central nervous system in immunocompromised patients. Survival following treatment of Aspergillus brain abscess has been reported only 4 times. In each case, craniotomy was performed for abscess drainage. We present a case of long-term survival following stereotactic drainage of a bilateral Aspergillus brain abscess. In all reported cases, including the present one, histological examination of the abscess contents established the correct diagnosis. Amphotericin B was used in combination with operation in 4 of the 5 cases of long-term survival.

✓ In an effort to reduce the incidence of postoperative wound infection, the recently proposed regimen of intravenous vancomycin and tobramycin and streptomycin irrigating solution was used in 878 neurosurgical operations. There were eight infections, for an infection rate of 0.9%. This infection rate was compared to the rate in the previously reported series using a sequential statistical analysis. The infection rate was found to be signficantly greater than that previously reported. Controlled clinical trials will be required before the efficacy of antibiotic prophylaxis in clean neurosurgical procedures can be considered proven.

This paper has reported on an investigation of the relationship between the external industrial classification of corporations and the statistical groupings that can be found in their corporate financial measurements. It appears that utilities and industrials are quite different in their financial characteristics. Five industrial classes also appear to be quite distinct, although somewhat less distinct than the industrial-versus-utility comparisons. Consequently, it appears that financial variables do tend to distinguish the various industrial classifications and that, with only a corporation's financial characteristics known, its industrial classification may be reliably determined.