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Our understanding of the complex relationship between schizophrenia symptomatology and etiological factors can be improved by studying brain-based correlates of schizophrenia. Research showed that impairments in value processing and executive functioning, which have been associated with prefrontal brain areas [particularly the medial orbitofrontal cortex (MOFC)], are linked to negative symptoms. Here we tested the hypothesis that MOFC thickness is associated with negative symptom severity.
This study included 1985 individuals with schizophrenia from 17 research groups around the world contributing to the ENIGMA Schizophrenia Working Group. Cortical thickness values were obtained from T1-weighted structural brain scans using FreeSurfer. A meta-analysis across sites was conducted over effect sizes from a model predicting cortical thickness by negative symptom score (harmonized Scale for the Assessment of Negative Symptoms or Positive and Negative Syndrome Scale scores).
Meta-analytical results showed that left, but not right, MOFC thickness was significantly associated with negative symptom severity (βstd = −0.075; p = 0.019) after accounting for age, gender, and site. This effect remained significant (p = 0.036) in a model including overall illness severity. Covarying for duration of illness, age of onset, antipsychotic medication or handedness weakened the association of negative symptoms with left MOFC thickness. As part of a secondary analysis including 10 other prefrontal regions further associations in the left lateral orbitofrontal gyrus and pars opercularis emerged.
Using an unusually large cohort and a meta-analytical approach, our findings point towards a link between prefrontal thinning and negative symptom severity in schizophrenia. This finding provides further insight into the relationship between structural brain abnormalities and negative symptoms in schizophrenia.
Firestone & Scholl (F&S) rely on three problematic assumptions about the mind (modularity, reflexiveness, and context-insensitivity) to argue cognition does not fundamentally influence perception. We highlight evidence indicating that perception, cognition, and emotion are constructed through overlapping, distributed brain networks characterized by top-down activity and context-sensitivity. This evidence undermines F&S's ability to generalize from case studies to the nature of perception.
Observations of Mars previously reported in 10 narrow bands between 3150 Å and 1.06 μ and in UBV are analyzed for brightness variations which correlate with longitude of the central meridian. Such an effect is found for λ ≥ 5000 Å, with some evidence for such a correlation at λ = 4570 Å. The data are then corrected to the mean (over longitude) brightness and a linear phase curve fitted to those observations with phase angle i ≥ 15°. An opposition effect (anomalous brightening at small phase angles) is found for wavelengths λ ≤ 5500 Å, in contrast to a result previously reported. The magnitude at zero phase, phase coefficient, and monochromatic albedo are computed for Mars as a function of wavelength.
Relatively lower executive functioning is characteristic of individuals with schizophrenia. As low socio-economic status (SES) early in life (i.e. parent SES) has been linked with lower executive skills in healthy children, we hypothesized that parental SES (pSES) would be more strongly related to executive functioning in individuals with schizophrenia than in controls and have a greater impact on prefrontal cortical morphology.
Healthy controls (n = 125) and individuals with schizophrenia (n = 102) completed tests assessing executive functioning and intelligence. The groups were matched on pSES, which was evaluated with the Hollingshead–Redlich scale. A principal components analysis (PCA) was conducted on 10 variables from six executive tests, yielding three specific components (fluency, planning and response inhibition). Voxel-based morphometry (VBM) was used to evaluate effects of pSES on gray matter (GM) concentration.
Lower pSES was associated with lower scores across the three executive functioning components, and a significant group by pSES interaction was observed such that low pSES, in particular, affected individuals with schizophrenia. These effects remained significant when intellectual ability, education and self-SES (sSES) were added as covariates. VBM revealed that lower pSES was associated with reduced GM volume in several anterior brain regions, especially the superior frontal gyrus, in patients but not in controls.
These findings suggest that individuals with schizophrenia may be particularly vulnerable to the adverse impact of low pSES, in terms of both lower executive skills and reduced anterior GM volumes.
As production workers in late-nineteenth-century American heavy industry moved towards regular use of concerted action, including the strike, to gain their demands, employers generally adopted rigid policies of opposition. That it was a frightening period for manufacturers, with prices for their goods steadily falling and widespread business failure, has been emphasized by Edward C. Kirkland and others. But lack of scholarship in business archives has improverished labor-management history on this point. Professors Skaggs and Ehrlich offer one case history, based on a study of the “inner truth” of such a conflict in the 1880s. It confirms the suspicion that it was not practical economic imperatives but a long-run policy to maintain the principles of paternalism that often accounted for the intransigence of management.
Previous studies have suggested that motivational aspects of executive functioning, which may be disrupted in schizophrenia patients with negative symptoms, are mediated in part by the striatum. Negative symptoms have been linked to impaired recruitment of both the striatum and the dorsolateral prefrontal cortex (DLPFC). Here we tested the hypothesis that negative symptoms are associated primarily with striatal dysfunction, using functional magnetic resonance imaging (fMRI).
Working-memory load-dependent activation and gray matter volumes of the striatum and DLPFC were measured using a region-of-interest (ROI) approach, in 147 schizophrenia patients and 160 healthy controls. In addition to testing for a linear relationships between striatal function and negative symptoms, we chose a second, categorical analytic strategy in which we compared three demographically and behaviorally matched subgroups: patients with a high burden of negative symptoms, patients with minimal negative symptoms, and healthy subjects.
There were no differences in striatal response magnitudes between schizophrenia patients and healthy controls, but right DLPFC activity was higher in patients than in controls. Negative symptoms were inversely associated with striatal, but not DLPFC, activity. In addition, patients with a high burden of negative symptoms exhibited significantly lower bilateral striatal, but not DLPFC, activation than schizophrenia patients with minimal negative symptoms. Working memory performance, antipsychotic exposure and changes in gray matter volumes did not account for these differences.
These data provide further evidence for a robust association between negative symptoms and diminished striatal activity. Future work will determine whether low striatal activity in schizophrenia patients could serve as a reliable biomarker for negative symptoms.
The crystallization and oxidation processes of thin, free-standing (FS), sputtered Cr films under the action of cw CO2 laser irradiation were studied by transmission electron microscopy (TEM) and transmission electron diffraction (TED). The crystallization is induced at power densities above 28.65 W cm−2, dwell time of 1 s, and the oxidation at power densities of 48.1 W cm−2 and longer dwell times.
A highly focused laser can be used to perform spatially selective photoelectrochemistry at semiconductor-electrolyte interfaces. These processes may be used for imaging (etching, deposition, etc.) or for nondestructive mapping of semiconductor properties from photoelectric response. A programmable laser scanner is described which can be used for both. An example of imaging is given for photoelectrochemical etching of pits in CdSe electrodes, which may be applied to archival data storage. Nondestructive evaluation is shown for a CdS crystal, in which the lateral distribution of subband gap photovoltage response is related to surface states incurred by polishing damage.
A preliminary study has been made of the UV photolysis of metal-organic compounds of Hg, Cd and Te which could be used for low-temperature, selective-area deposition of cadmium mercury telluride (CMT). High-resolution UV absorption spectra have been measured for dimethylcadmium (CdMe2), dimethylmercury (HgMe2) and diethyltelluride (TeEt2). Possible modes for photodissociation are discussed in the light of these results. The photodissociation of these alkyls was attempted in a hydrogen stream at atmospheric pressure using a mercury-xenon lamp, deposition being being onto a silica reaction tube. Yields of Cd, Hg and Te were measured under different deposition conditions to determine the dependence on UV intensity, alkyl concentration and flow velocity.
Photo-induced growth of ZnS on CdS has been studied using amorphous (thin film) and single-crystal substrates. The effect has been found to occur for light of wavelength shorter than the CdS absorption edge; a maximum light-induced thickness enhancement of 700 Å has been obtained for the ZnS film, with a growth rate of 2000 Å/min. The lightinduced growth, with its observed “memory” of several minutes is consistent with photo-desorption of an adlayer.
Laser-induced periodic pattern formation has been observed on a variety of substances. In particular, low-power lasers have been used to deposit a pattern on a metal surface. For a relatively smooth surface grating, this pattern can be explained in terms of a perturbative solution of Maxwell's equations. However, as the surface grating is enhanced by this initial deposition, the perturbative solution breaks down. An alternate non-perturbative solution of Maxwell's equations for such rough surfaces is considered here.
Gallium phosphide is an important III-V semiconductor material for fabricating strained layer superlattices and high-speed and high-temperature microelectronics. Etching of this compound semiconductor with conventional techniques presents problems which may be solved by photon-induced electro-chemistry. We have shown that rapid localized etching of n-GaP in KOH can be driven with the UV lines of an argon-ion laser. The level and type of doping and the laser intensity determine the etch rates, which are nearly 60 nm/sec at 3500 Wcm−2 for n-doped material.
By using two interfering laser beams to initiate localized chemical reactions at an interface, very high resolution, maskless microfabrication can be done over relatively large substrate areas. The resulting deposited or etched patterns can be used in a variety of electrooptical and electronic applications. In addition, this type of fabrication, which can be monitored in real time, provides insight into many new interfacial phenomena.
Surface-dressed optical Bloch equations are derived for the purpose of evaluating the resonance fluorescence spectrum of two interacting identical atoms near or adsorbed on a metal surface. The derivation takes into account the influence of reflected photons, dephasing due to atomic collisions, the linewidth of the driving laser field and the resonance excitation of surface plasmons. A unique behavior of the surfacemodified fluorescence, not seen in analogous gas cell experiments, is predicted. Under the appropriate circumstance, a photon emitted from one of the two atoms can be trapped by the two-adatom-surface system, and this is studied by means of a theory which treats the atoms and their surface images on the same footing.
Cobalt interconnects were deposited with a cw visiblewavelength laser from gaseous Co2 (CO)8. The deposited material was high-purity Co, and its electrical resistivity was as low as 13 μΩ-cm (twice that of bulk resistivity). The deposition is initiated by photochemical decomposition of Co2 (CO)8, and therefore process parameters (pressure, power, writing speed) are insensitive to the optical and thermal properties of the substrate.
The gas phase photochemistry of an LCVD reactor used to grow polycrystalline Ge films was studied by absorption and emission spectroscopy. Upon photodissociating GeH4 (5% in an Ar or He carrier) at 248 nm (KrF laser), excited states of Ge and GeH are produced. Spatially, spectrally and temporally resolved atomic and molecular emissions are monitored as a function of gas pressure and laser intensity. These data lead to the conclusion that GeH2 is predominantly produced directly from GeH4 by The simultaneous absorption of two 5 eV (λ = 248 nm) photons.
Using CMOS, poly-Si gate, single-level metal, gate-array chips, techniques have been developed to reconfigure the interconnect metallization on individual circuits without degradation of device or circuit performance. These techniques involve a laser-assisted capillary wet-etch process for highly selective removal of Al-alloy interconnects and laser CVD of doped poly-Si links. This technique may be useful for prototyping, testing and optimization of gate-array and standard-cell designs and layouts.
The properties of SiO2 and Si3 N4 films deposited by an ArF excimer laser, glow discharge electron beam and conventional plasma-enhanced CVD are compared. The deposition apparatus, technique, and conditions in addition to the physical, chemical and electrical properties of the films are discussed.
When a new and promising thermoelectric material is discovered, an effort is undertaken to improve its “figure of merit”. If the effort is to be more efficient than one of trial and error with perhaps some “rule of thumb guidance” then it is important to be able to make the connection between experimental data and the underlying material characteristics, electronic and phononic, that influence the figure of merit. Transport and fermiology experimental data can be used to evaluate these material characteristics and thus establish trends as a function of some controllable parameter, such as composition. In this paper some of the generic-materials characteristics, generally believed to be required for a high figure of merit, will be discussed in terms of the experimental approach to their evaluation and optimization. Transport and fermiology experiments will be emphasized and both will be outlined in what they can reveal and what can be obscured by the simplifying assumptions generally used in their interpretation.