The lakes of Titan.

The surface of Saturn's haze-shrouded moon Titan has long been proposed to have oceans or lakes, on the basis of the stability of liquid methane at the surface. Initial visible and radar imaging failed to find any evidence of an ocean, although abundant evidence was found that flowing liquids have existed on the surface. Here we provide definitive evidence for the presence of lakes on the surface of Titan, obtained during the Cassini Radar flyby of Titan on 22 July 2006 (T16). The radar imaging polewards of 70 degrees north shows more than 75 circular to irregular radar-dark patches, in a region where liquid methane and ethane are expected to be abundant and stable on the surface. The radar-dark patches are interpreted as lakes on the basis of their very low radar reflectivity and morphological similarities to lakes, including associated channels and location in topographic depressions. Some of the lakes do not completely fill the depressions in which they lie, and apparently dry depressions are present. We interpret this to indicate that lakes are present in a number of states, including partly dry and liquid-filled. These northern-hemisphere lakes constitute the strongest evidence yet that a condensable-liquid hydrological cycle is active in Titan's surface and atmosphere, in which the lakes are filled through rainfall and/or intersection with the subsurface 'liquid methane' table.

Titan Radar Mapper observations from Cassini's T3 fly-by.

Cassini's Titan Radar Mapper imaged the surface of Saturn's moon Titan on its February 2005 fly-by (denoted T3), collecting high-resolution synthetic-aperture radar and larger-scale radiometry and scatterometry data. These data provide the first definitive identification of impact craters on the surface of Titan, networks of fluvial channels and surficial dark streaks that may be longitudinal dunes. Here we describe this great diversity of landforms. We conclude that much of the surface thus far imaged by radar of the haze-shrouded Titan is very young, with persistent geologic activity.

The sand seas of Titan: Cassini RADAR observations of longitudinal dunes.

The most recent Cassini RADAR images of Titan show widespread regions (up to 1500 kilometers by 200 kilometers) of near-parallel radar-dark linear features that appear to be seas of longitudinal dunes similar to those seen in the Namib desert on Earth. The Ku-band (2.17-centimeter wavelength) images show approximately 100-meter ridges consistent with duneforms and reveal flow interactions with underlying hills. The distribution and orientation of the dunes support a model of fluctuating surface winds of approximately 0.5 meter per second resulting from the combination of an eastward flow with a variable tidal wind. The existence of dunes also requires geological processes that create sand-sized (100- to 300-micrometer) particulates and a lack of persistent equatorial surface liquids to act as sand traps.

Cassini radar views the surface of Titan.

The Cassini Titan Radar Mapper imaged about 1% of Titan's surface at a resolution of approximately 0.5 kilometer, and larger areas of the globe in lower resolution modes. The images reveal a complex surface, with areas of low relief and a variety of geologic features suggestive of dome-like volcanic constructs, flows, and sinuous channels. The surface appears to be young, with few impact craters. Scattering and dielectric properties are consistent with porous ice or organics. Dark patches in the radar images show high brightness temperatures and high emissivity and are consistent with frozen hydrocarbons.

A retrospective clinical, laboratory and outcome analysis in 43 cases of acute aseptic meningitis.

Forty-three consecutive cases of acute aseptic meningitis (AAM) presenting within a 24-months period were retrospectively analysed with respect to clinical symptomatology, cerebrospinal fluid (CSF) findings, clinical course, treatment and outcome. Nineteen of the 43 AAM cases (44%) were caused by enterovirus, one by HIV (2%), two by Varicella zoster virus (5%), three due to herpes simplex virus I (7%), two due to herpes simplex virus II (5%), one due to Central European encephalitis virus (2%), and in 15 patients (35%) the aetiology of AAM remained unknown. Headache (100%) and fever (93%) were the presenting symptoms in the majority of cases. Signs of preceding infection were predominantly gastrointestinal in the enterovirus subgroup, but were inconsistently observed in the other subgroups. CSF findings at the first lumbar tap on admission generally revealed lymphomonocytic pleocytosis of less than 500 cells per micro l, mild to moderately elevated protein and normal lactate and glucose levels. Initial therapy consisted of an empirical antiviral and antibiotic regimen until a serological diagnosis was available. Acyclovir, effective only in herpes family viruses, was initially administered to all AAM cases. Effective therapy for other viral pathogens are not broadly available and treating AAM of unknown aetiology imposes a particular problem. The average hospitalization time ranged from 16 to 31 days. Patients were either discharged home (72%) or transferred to a rehabilitation centre (28%). The outcome was good (40%) to fair (51%) in the majority of cases.

Three species of Borrelia burgdorferi sensu lato (B. burgdorferi sensu stricto, B afzelii, and B. garinii) identified from cerebrospinal fluid isolates by pulsed-field gel electrophoresis and PCR.

A total of 36 European Borrelia burgdorferi sensu lato cerebrospinal fluid isolates (mainly from southern Germany) were analyzed by pulsed-field gel electrophoresis (PFGE) for large restriction fragment pattern (LRFP) and linear plasmid profiles. Analyzing this large panel of isolates, we detected all three species of B. burgdorferi sensu lato pathogenic for humans in cerebrospinal fluid from patients with Lyme neuroborreliosis by PFGE typing after MluI digestion: 21 B. garinii (58%), 10 B. afzelii (28%), and 4 B. burgdorferi sensu stricto (11%) strains as well as 1 isolate with bands characteristic of both B. afzelii and B. garinii. Species classification by PFGE typing was confirmed by 16S rRNA-specific PCR. Eighteen isolates (11 B. garinii, 6 B. afzelii, and 1 B. burgdorferi sensu stricto isolate) were further characterized by LRFP with four different restriction enzymes (ApaI, KspI, SmaI, and XhoI). All B. afzelii isolates showed identical patterns for each restriction enzyme group. Considerable heterogeneity was demonstrated within the B. garinii group. Subsequent analysis of plasmid profiles revealed only marginal differences for B. afzelii strains but different patterns for B. garinii isolates. In one B. afzelii strain we found a linear plasmid of about 110 kbp not described before. LRFP analysis by PFGE is a suitable tool for the molecular characterization of B. burgdorferi sensu lato strains and allows determination not only of the species but also of the subtypes within B. garinii.

Differentiation of Borrelia burgdorferi sensu lato strains isolated from skin biopsies and tick by pulsed-field gel electrophoresis.

Fifteen isolates of Borrelia burgdorferi sensu lato from skin biopsies (8) and ticks (7) were investigated for species differentiation by pulsed-field gel electrophoresis (PFGE). The skin isolates were further characterized by plasmid profile as well as SDS-PAGE and revealed six Borrelia afzelii-, one Borrelia burgdorferi sensu stricto-, and one Borrelia garinii species. The tick isolates showed three Borrelia afzelii--and four Borrelia garinii species. The skin isolates could be further discriminated by plasmid profile analysis--all strains showed an individual pattern. The SDS-PAGE of whole-cell lysates obtained from skin isolate showed a different protein pattern for each of the skin isolates.

Molecular characterization of Borrelia burgdorferi sensu lato strains by pulsed-field gel electrophoresis.

The large restriction fragment patterns (LRFP) and linear plasmid profiles of eight tick isolates of Borrelia burgdorferi sensu lato were investigated with pulsed-field gel electrophoresis (PFGE). The whole cell lysate was examined with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The MluI LRFP differentiates two species of Borrelia burgdorferi sensu lato (Borrelia burgdorferi sensu stricto and Borrelia garinii). LRFP is a suitable method to demonstrate genetic hetero- or homogeneity of isolates within one species without subsequent hybridization utilizing diverse probes. Different strains with similar or identical LRFP can be further discriminated by plasmid profile analysis. Our results show that each strain analyzed had a different plasmid profile. Therefore the linear plasmid profile has a potential application as a strain typing procedure. SDS-PAGE of whole-cell lysate supports the findings of homology within the B. burgdorferi sensu stricto species and the heterology within the B. garinii species.

Continuous, real-time, noninvasive monitor of blood pressure: Penaz methodology applied to the finger.

The finger blood pressure monitor measures blood pressure continuously and noninvasively by means of a technique described by J. Penaz. The size of the artery is measured when its internal pressure (arterial pressure) equals the external pressure. (At this point, transmural pressure equals zero and the arterial wall is said to be "unloaded.") This unloaded condition is maintained by continuous, automatic adjustments of external pressure on the artery, adjustments that are made simultaneously with and parallel to intraarterial pressure variations. The external pressure then constantly equals internal pressure (arterial blood pressure) and is reported by the monitor as values for systolic, mean, and diastolic pressure. A finger cuff with a built-in light source and detector is used to measure finger artery size, and an inflatable bladder is used to apply the external pressure to the artery. The monitor is microprocessor based; algorithms determine the unloaded artery size approximately every minute and automatically correct for changes possibly induced by smooth muscle contraction or relaxation, and a high-speed electropneumatic servo control system enables automatic calibration and adjustment.