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Gamma-butyric acid (GABA) dysfunction has been implicated in the pathophysiology of schizophrenia and its cognitive deficits. Proton magnetic resonance spectroscopy (MRS) was used to test the hypothesis that older participants with schizophrenia have lower anterior cingulate GABA levels compared with older control participants. One-hundred forty-five participants completed this study. For detection of GABA, spectra were acquired from the medial frontal/anterior cingulate cortex using a macromolecule-suppressed MEGA-PRESS sequence. Patients were evaluated for psychopathology and all participants completed neuropsychological tests of working memory, processing speed and functional capacity. GABA levels were significantly lower in the older participants with schizophrenia (n=31) compared with the older control (n=37) group (P=0.003) but not between the younger control (n=40) and schizophrenia (n=29) groups (P=0.994). Age strongly predicted GABA levels in the schizophrenia group accounting for 42% of the variance, but the effect of age was less in the control group accounting for 5.7% of the variance. GABA levels were specifically related to working memory but not processing speed performance, functional capacity, or positive or negative symptom severity. This is the largest MRS study of GABA in schizophrenia and the first to examine GABA without macromolecule contamination, a potentially significant issue in previous studies. GABA levels more rapidly declined with advancing age in the schizophrenia compared with the control group. Interventions targeted at halting the decline or increasing GABA levels may improve functional outcomes and quality of life as patients with schizophrenia age.

Peatland drainage depletes large carbon stocks by increasing carbon dioxide (CO2) emissions from the soil. Restoration via re‐wetting could play an important role in climate change mitigation, reducing CO2emissions and increasing C storage within peatlands. However, re‐wetting leads to a biogeochemical compromise between increased CO2uptake, and enhanced methane (CH4) release. The extent of this compromise in re‐wetted ecosystems with differing environmental conditions is uncertain. To assess re‐wetting effects, we analyzed eddy‐covariance flux measurements from a temperate bog near Vancouver, Canada, from two sites that have undergone different restoration techniques. By the end of the 1‐year study period, the actively re‐wetted, wetter site, was a weak CO2sink (−26.1 ± 6.1 g C‐CO2m−2), and the passively re‐wetted, drier site, was near CO2neutral (3.8 ± 3.1 g C‐CO2m−2). Higher CH4emissions at the wetter site led to a larger radiative balance on 20‐ and 100‐year time horizons, implying that the strong radiative effect of CH4can offset CO2sink strength on shorter to medium timeframes. However, long‐term radiative forcing (RF) modeling suggests sustained CO2uptake by the wetter site will eventually lead to a cooling effect on the climate. Furthermore, modeling results emphasize that despite both re‐wetted peatland sites having a positive RF over century timescales, the lack of restoration would have resulted in a significantly larger RF beyond the first few decades following restoration. Results highlight the importance of actively re‐wetting disturbed peatlands to mitigate climate warming and can be used to inform management decisions. Peatlands are important ecosystems in the global carbon cycle as their soils can store vast quantities of carbon. However, when soils in peatlands are disturbed via drainage, they dry and release carbon dioxide (CO2) into the atmosphere, contributing to global warming. Scientists have proposed re‐wetting drained peatlands to reverse this effect and promote CO uptake. This can be an issue, because wet conditions often lead to increased emissions of methane (CH4), a much more potent greenhouse gas (GHG). This study presents results comparing GHG and environmental measurements from two peatlands undergoing restoration near Vancouver, Canada—one wetter, and one drier site. Restoration of both sites has a climate benefit compared to not re‐wetting, however, results reveal that although the wetter site had higher CH4emissions, it was a larger CO2sink than the drier site, and therefore will eventually have a cooling effect on the climate on long timescales. These results are useful for identifying which environmental conditions in re‐wetted peatlands are most beneficial for the climate. Of two rewetted peatland sites, wetter conditions at one site corresponded with it being a stronger carbon dioxide sinkThe wetter site was a larger methane source than the drier one, resulting in a greater radiative balance on 20‐ and 100‐year timeframesOver century timescales, the wetter site had a lower (eventually negative) radiative forcing, and overall rewetting had climatic benefits Of two rewetted peatland sites, wetter conditions at one site corresponded with it being a stronger carbon dioxide sink The wetter site was a larger methane source than the drier one, resulting in a greater radiative balance on 20‐ and 100‐year timeframes Over century timescales, the wetter site had a lower (eventually negative) radiative forcing, and overall rewetting had climatic benefits

Abstract:  A square packed array of square-channels with long channel axis aligned radially is a useful structure for condensing grazing incidence flux to a focus. These devices, known as Lobster-eye optics for their similarity to the eyes of the macruran crustaceans, show great promise as the focusing optic in the next generation of X-ray all-sky monitors. At X-ray wavelengths the optimal Lobster-eye structure requires an aspect ratio of channel length to width of greater than 30:1. Following recent success in fabricating a low aspect ratio Lobster-eye structure, we discuss some of the parameters for, and production issues involved in making, a useful Lobster-eye prototype using LIGA. We report on our initial attempts to produce high aspect ratio Lobster-eye optics using the LIGA process with a graphite substrate.

We demonstrate quantitative phase imaging of a neutral atomic beam by using a noninterferometric technique. A collimated thermal atomic beam is phase shifted by an off-resonant traveling laser beam with both a Gaussian and a TEM_01 profile and with both red and blue detuning of as much as 50 GHz. Phase variations of more than 1000 rad were recovered from velocity-selective measurements of the propagation of the atomic beam and were found to be in quantitative agreement with theoretical predictions based on independently measured phase object intensity profiles and detunings.

We present a measurement of the intensity around the focus of a N.A.-0.95 lens using a tapered optical fiber probe. An asymmetry introduced by the vector nature of the incident polarized light is evident, although it is inconsistent with that predicted theoretically by considering the magnitude squared of the electric field. The sensitivity of the probe to different components of the electromagnetic field is considered, and it is shown that the measurement is consistent with vector diffraction theory when the probe properties are taken into account.

Near-field scanning optical microscopy (NSOM) is used to measure the evanescent field surrounding a biconically tapered optical fibre sensor in air, water and dimethyl sulfoxide solution. These measurements are found to be in good agreement with those theoretically predicted using the finite difference - beam propagation method in combination with refractive and atomic force microscope measurements, demonstrating the validity of the model described for a number of environments.

Recent papers have shown that there are different coherent and partially coherent fields that may have identical intensity distributions throughout space. On the other hand, the well-known transport-of-intensity equation allows the phase of a coherent field to be recovered from intensity measurements, and the solution is widely held to be unique. A discussion is given on the recovery of the structure of both coherent and partially coherent fields from intensity measurements, and we reconcile the uniqueness question by showing that the transport-of-intensity equation has a unique solution for the phase only if the intensity distribution has no zeros.

A new technique is proposed for the recovery of optical phase from intensity information. The method is based on the decomposition of the transport-of-intensity equation into a series of Zernike polynomials. An explicit matrix formula is derived, expressing the Zernike coefficients of the phase as functions of the Zernike coefficients of the wave-front curvature inside the aperture and the Fourier coefficients of the wave-front boundary slopes. Analytical expressions are given, as well as a numerical example of the corresponding phase retrieval matrix. This work lays the basis for an effective algorithm for fast and accurate phase retrieval.

In a previous paper [ J. Opt. Soc. Am. A12, 1932 ( 1995)] we presented a method for phase recovery with the transport-of-intensity equation by use of a series expansion. Here we develop a different method for the solution of this equation, which allows recovery of the phase in the case of nonuniform illumination. Though also based on the orthogonal series expansion, the new method does not require any separate boundary conditions and can be more easily adjusted for apertures of various shapes. The discussion is primarily for the case of a circular aperture and Zernike polynomials, but we also outline the solution for a rectangular aperture and Fourier harmonics. The latter example may have some substantial advantages, given the availability of the fast Fourier transform.

A method for calculating the image distribution for one-dimensional lobster-eye optics is presented. This method gives the image distribution exactly for certain cases and offers improved speed over the method of ray tracing. Examples of the use of the algorithm are given. We show that the algorithm gives the same results as detailed ray-tracing codes. Extension of the method to the two-dimensional case is discussed.

Protoplast fractionation techniques were used to prepare subcellular fractions of three strains of Staphylococcus aureus for the analysis of alpha-hemolysin activity. More than 90% of the cellular hemolytic activity was localized in the periplasm, only a trace was detected in the cytoplasm, and none was found in either plasma membranes or mesosomes. This cellular portion constituted approximately 4 to 10% of the total hemolytic activity of the culture. The erythrocyte lysis spectrum and Sephadex G-100 filtration studies indicated that the cellular hemolysin closely resembles the extracellular form.

Staphylococus aureus, ATCC 6538P, was fractionated into protoplast membranes, mesosomal vesicles, periplasm, and cytoplasm. These fractions and the culture fluid were then assayed for various degradative enzyme activities. They were not restricted to a single fraction nor dispersed homogeneously, but were distributed predominantly (on the basis of specific activity) as follows: nuclease in the culture fluid; alkaline phosphatase, 5′-nucleotidase, and acid phosphatase in the periplasm; adenosine triphosphatase in the protoplast membrane; and protease (low levels) in mesosomal vesicles. No significant esterase nor cell wall hydrolytic activity was found in any fraction. S. aureus80/81 was studied for penicillinase activity after induction with benzyl penicillin; this enzyme was localized in the mesosomal vesicles. Electron microscopy did not reveal any ultrastructural changes associated with secretion of the extracellular fraction. Overall, these studies demonstrate that degradative enzymes are located in several surface compartments and that, therefore, the mesosome does not function as a prototype lysosome in S. aureus.

Focusing and collimation of 8 keV x rays has been demonstrated using microchannel plate (MCP) blanks with cylindrical channels. The focusing effect arises from total external reflection of x rays at the interior surfaces of the channels of a MCP and has been described previously by the authors. Point to point focusing was observed with flat and curved MCPs, and collimation from a point source to a quasi-parallel beam was observed with a curved MCP. Intensity profiles at the image plane and at other planes behind a flat MCP were obtained for a 20 × 40 μm2x-ray source, and agree well with theoretical predictions. The flux in a 40-μm-diameter collector in the image plane was compared with the flux in the same plane, but without a MCP. The relative gain in flux increases linearly with the source to MCP distance, as predicted. A maximum relative gain in flux of 18 ± 1 was observed for a source to detector distance of 50 cm.

Summary Calcium channel blockers reduce Ca++ flux through membrane channels and may inhibit intracellular Ca++-dependent synthetic and regulatory activities by binding to calmodulin. We have found that Verapamil, a calcium channel blocker, inhibits influenza virus replication in Madin-Darby canine kidney cells and in murine pulmonary macrophages and that this antiviral effect occurs with drug addition late in the replication cycle. Chlorpromazine, a drug which binds to calmodulin, also inhibited influenza virus replication in these tissue culture systems. We suggest that Verapamil and chlorpromazine inhibit influenza virus replication by interfering with calmodulin-dependent intracellular activities necessary for late synthetic steps or virus assembly steps and that calcium channel blockers provide a new probe for investigating influenza virus replication.

We report an experimental investigation and comparison with simulation of the x-ray focusing of a flat, square profile microchannel plate. We use x rays with an energy of ~1.5 keV from a laser-produced plasma. The images were recorded with x-ray film. We find the focal structure to be consistent with theoretical expectations. The angular resolution of the focus is 0.96 mrad, which is a major improvement over previous results. The measured peak intensity gain is 27 ± 4, which is ~33% of that for a perfect optic.

BACKGROUND: Recent work has demonstrated a correlation between frequency of aspirin ingestion and colorectal cancer prevention. Sulindac, another nonsteroidal anti-inflammatory drug (NSAID), has been shown to cause polyp regression and a fall in cell proliferation in patients with familial adenomatous polyposis, who are destined to develop colorectal cancer unless the colon is removed. However, the mode of action of NSAIDs in colorectal carcinogenesis prevention remains to be determined, although a prostaglandin-mediated mechanism seems likely. METHODS: Rectal or duodenal biopsies from 20 patients with familial adenomatous polyposis, who had been randomized to sulindac or placebo, were analyzed for prostaglandin (PG) E2 and E2α levels before and after treatment. RESULTS: A significant fall in prostaglandin E2 and E2α (P=0.0096; PGE2, P=0.036; PGF2α Spearman's rank correlation). CONCLUSIONS: Nonsteroidal antiinflammatory drugs may prevent colorectal cancer by their inhibition of prostaglandin synthesis. Prostaglandins may be implicated in carcinogenesis through an increase in cell proliferation, through immunosuppression, by increasing neovascularization, or via a mutagenic effect.

PURPOSE: Despite the introduction of screening, surveillance, and prophylactic colectomy surgery, patients with familial adenomatous polyposis (FAP) are at risk of dying from other malignancies. METHODS: In order to quantify this risk and identify the causes of mortality, a retrospective life table analysis was performed on 222 patients with familial adenomatous polyposis who had undergone a total colectomy and ileorectal anastomosis between 1948 and 1990. These FAP patients were compared with an age- and sex- matched group of the general population and a relative risk of dying was calculated. RESULTS: Of 222 patients, 53 have died. In a matched group of the general population the expected number of deaths would be 15.8. The relative risk of dying is therefore 3.35. There has been no significant improvement with time and the relative risk is greatest for female patients. CONCLUSION: The three main causes of mortality are upper gastrointestinal malignancy, desmoid disease, and perioperative complications. Further research should therefore be aimed at prevention and improved treatment of these in order to improve survival.

Several investigations of host and bacterial factors critical to staphylococcal clearance from lungs suggest that alveolar macrophages may not provide the principal defense against inhaled staphylococci. We evaluated possible contributions of extracellular bactericidal activities in lungs with a standard aerosol challenge model by using methods which allowed recovery of macrophages for in vitro bactericidal assays and recovery of intrapulmonary staphylococci for clearance studies. Macrophages recovered by a gentle lavage technique immediately after aerosol exposure contained 6.0 +/- 2.3 colony-forming units of viable staphylococci per 100 glass-adherent macrophages. These intracellular staphylococci were killed in vitro with a half-life of 10.8 +/- 2.1 h, which is identical to our results with a completely in vitro system for ingestion and killing. However, 99.4 +/- 0.2% and 94.9 +/- 1.5% of the viable cocci recovered in bronchoalveolar lavage at 0.5 and 6.0 h after aerosol exposure were sensitive to lysostaphin, a rapidly bactericidal enzyme with no demonstrable activity against intracellular organisms and therefore, presumably extracellular. Photomicrographs from lavage pellets obtained 0.5, 1.5, 3.0, and 5.5 h after aerosol exposure confirmed the presence of numerous extracellular cocci. These extracellular cocci were eliminated at the same rate as whole lung cocci (half-life = 3.07 and 3.14 h, respectively) and at a much faster rate than intracellular cocci. In summary, we found large numbers of extracellular staphylococci in bronchoalveolar spaces during the first 6 h after aerosol exposure that are inactivated at the same rate as the whole lung bacterial population. Since only a small number of staphylococci are ingested by macrophages and intracellular bactericidal activity appears too slow to explain intrapulmonary killing, we conclude that an as yet unidentified extracellular killing process contributed to staphylococcal clearance.

Light described by a certain class of coherence function is investigated, and simple results are found to describe the diffraction patterns. A physical basis for these results is presented. The results are discussed in the context of coherence measurement techniques based on diffraction measurements.