In situ measurements of Saturn's ionosphere show that it is dynamic and interacts with the rings.

The ionized upper layer of Saturn's atmosphere, its ionosphere, provides a closure of currents mediated by the magnetic field to other electrically charged regions (for example, rings) and hosts ion-molecule chemistry. In 2017, the Cassini spacecraft passed inside the planet's rings, allowing in situ measurements of the ionosphere. The Radio and Plasma Wave Science instrument detected a cold, dense, and dynamic ionosphere at Saturn that interacts with the rings. Plasma densities reached up to 1000 cubic centimeters, and electron temperatures were below 1160 kelvin near closest approach. The density varied between orbits by up to two orders of magnitude. Saturn's A- and B-rings cast a shadow on the planet that reduced ionization in the upper atmosphere, causing a north-south asymmetry.

Dust observations at orbital altitudes surrounding Mars.

Dust is common close to the martian surface, but no known process can lift appreciable concentrations of particles to altitudes above ~150 kilometers. We present observations of dust at altitudes ranging from 150 to above 1000 kilometers by the Langmuir Probe and Wave instrument on the Mars Atmosphere and Volatile Evolution spacecraft. Based on its distribution, we interpret this dust to be interplanetary in origin. A comparison with laboratory measurements indicates that the dust grain size ranges from 1 to 12 micrometers, assuming a typical grain velocity of ~18 kilometers per second. These direct observations of dust entering the martian atmosphere improve our understanding of the sources, sinks, and transport of interplanetary dust throughout the inner solar system and the associated impacts on Mars's atmosphere.

Cooperative adsorption behavior of phosphopeptides on TiO2 leads to biased enrichment, detection and quantification.

The adsorption behavior of phosphopeptides onto TiO2 surfaces was studied using the quartz crystal microbalance with dissipation monitoring (QCM-D) as the main experimental technique. The main focus is the characterization of the emergence of positive cooperativity under conditions where the peptides have a positively charged C-term. It is shown that when carrying no net charge, small water-soluble peptides as a rule develop positive cooperativity. The impact of the adsorption mechanism on the outcome of TiO2 based enrichment methods was investigated with the help of matrix assisted laser desorption-ionization mass spectrometry (MALDI-MS). The data presented illustrate how the phosphopeptide profile in the enriched material may deviate from that in the native sample, as cooperative phosphopeptides are overrepresented in the former. Furthermore, commonly employed washing and elution solutions may facilitate preferential release of certain peptides, leading to further bias in the recovered sample. Taken together, the results of the present study demonstrate that thorough understanding of the mechanisms behind the adsorption of phosphopeptides on the enrichment material is necessary in order to develop reliable qualitative and quantitative methods for phosphoproteomics.

Cassini measurements of cold plasma in the ionosphere of Titan.

The Cassini Radio and Plasma Wave Science (RPWS) Langmuir probe (LP) sensor observed the cold plasma environment around Titan during the first two flybys. The data show that conditions in Saturn's magnetosphere affect the structure and dynamics deep in the ionosphere of Titan. The maximum measured ionospheric electron number density reached 3800 per cubic centimeter near closest approach, and a complex chemistry was indicated. The electron temperature profiles are consistent with electron heat conduction from the hotter Titan wake. The ionospheric escape flux was estimated to be 10(25) ions per second.

Excitation of localized rotating waves in plasma density cavities by scattering of fast magnetosonic waves.

An analytic description of electromagnetic waves in an inhomogeneous plasma is applied to investigate excitation of localized rotating waves below the lower hybrid frequency through scattering of fast magnetosonic waves on a density cavity. The magnetosonic wave is focused to left-handed rotating oscillations. We find the amplitude of the localized oscillations, resonance frequencies, and the width of the resonances. The theory is relevant for the lower hybrid solitary structures observed in space plasmas and is shown to be consistent with observations by the Freja satellite.

The management of chondrosarcoma of bone.

Chondrosarcomas of bone are among the most difficult problems in diagnosis and management in the field of orthopaedic oncology. In addition to the variability of presentation of the "standard" hyaline, myxoid or fibrous types of lesion, three unusual forms of the tumor are now recognized--mesenchymal, clear cell and dedifferentiated--which show differences in their biologic behavior. Chondrosarcomas, with only rare exception, are radio-resistant and show only a limited response to adjunctive chemotherapy. The optimal therapy at present is surgical, but clearly the type of surgical procedure selected should vary with the malignity and extent of the tumor in order to avoid either undertreatment (resulting in a high rate of local recurrence and/or distant metastases) or excessive and unnecessary sacrifice of normal tissue. Patients suspected of having chondrosarcomas should be thoroughly evaluated by clinical examination, radiographic and special studies to define as fully as possible the site and extent of the local tumor, the presence or absence of a soft-tissue mass and the existence of distant metastases. A biopsy should be performed through an incision which can be subsequently excised during the definition procedure. The tissue obtained should be graded histologically and the clinical and radiologic data added to define whether the lesion is benign or a low-grade or high-grade chondrosarcoma. Using a special system recently described by Enneking and Spanier, the lesions should be evaluated on the basis of the grade (G1 or G2); the site of the lesion in relation to the anatomic compartments (T1 or T2) and the presence or absence of distant metastasis (M0 or M1). Based on a scheme presented in this article, the appropriate one of four grades of surgical procedures should be chosen. For benign tumors, Grade I procedures (intralesional curettage or excision) are generally adequate. For Stage IA tumors, occasionally a Grade II procedure, marginal excision may be sufficient, but more frequently Grade III procedures (wide intracompartmental resections) are indicated. Stage IIA and IIB lesions should be treated with Grade III or Grade IV (radical resection) surgical procedures. The treatment of inoperable or Stage IV tumors (those with metastasis) is unsatisfactory and consists of palliative resections, radiation therapy and chemotherapy.