Spontaneous Onset of Bacterial Cellulitis in Lower Limbs with Chronic Obstructive Venous Disease

AbstractBackgroundCellulitis, often recurrent is a common complication of severe chronic venous disease (CVD) when dermatitis or ulcer is present. The skin breakdown obviously provides easy entry for bacteria but other factors such as oedema and lymphatic dysfunction likely play a role in pathogenesis as well. An iliac obstructive lesion is commonly present and correction with stent(s) often heals dermatitis/ulcer and relieves cellulitis. The current manuscript focuses on a relatively infrequent “spontaneous” variety of cellulitis which also occurs in obstructive venous disease in the absence of overt skin breakdown. Stenting results are of particular interest in this subset because its therapeutic efficacy can be related to factors other than healing of dermatitis/ulceration (portal of entry).Material and methodsOne thousand and nine limbs underwent iliac vein stenting for symptomatic CVD over a 7 year period; 29 limbs that were stented to treat spontaneous recurrent cellulitis of two or more prior attacks and 16 additional limbs with only one prior episode (stented for other indications) are analysed. Eighty two percent of the limbs had obvious swelling and the remainder had none at the time of stenting when cellulitis was inactive. Iliac vein outflow obstruction was found by intravascular ultrasound (IVUS) and all limbs were stented.ResultsMedian age was 54 and male to female ratio 1:2. Aetiology of iliac obstruction was post-thrombotic in 33% and non-thrombotic in 67%. Preoperatively, lymphatic abnormalities were present in 17 (38%) of the limbs: no activity in 7, delayed flow in 8 and pooling of isotope in the lower leg in 2 limbs. Swelling and pain improved significantly after stent placement. Cumulative freedom from recurrent attacks of cellulitis was 76% at 3 years.ConclusionIliac vein outflow obstruction may underlie CVD limbs afflicted with cellulitis. IVUS examination is recommended if cellulitis is recurrent and conventional therapy had failed. Correction of outflow obstruction by venous stent placement appears to yield moderate freedom from repeat infections in the near term

Evidence of a biodiversity crisis documented on a peritidal carbonate succession from western Tethys (Sicily): new data on the End Triassic Mass Extinction

A biodiversity crisis was observed in the latest Triassic on both macro-and micro-benthic communities from a western Tethyan carbonate platform. The studied succession represented by the Monte Sparagio section consists of a continuous Upper Triassic to Lower Jurassic peritidal limestones organized in shallowing upward cycles. The subtidal facies in the lower part of this section (Unit A) contains very abundant and highly diverse fossiliferous assemblages consisting of very large megalodontoids (up to 40 cm). Up-section, a reduction of biodiversity, abundance and shell size of megalodontoids (up to 15 cm) tipifies Unit B. Similarly, in this last Unit, the average dimensions of the benthic foraminifer T. hantkeni decreases (ca. 30%). After a short interval marked by a bloom of the problematic alga T. parvovesiculifera, the overlying Unit C accounts for the recovery of the Jurassic benthic community. The geochemical analyses of stable isotopes (C, O and S) seem correlative to the drastic reduction in the Rhaetian biodiversity between Unit A and Unit B. These biodiversity crises in the Rhaetian horizons can be interpreted as a precursor of the End Triassic Extinction and provide new insights into the existence of two extinction pulses at the end of Triassic. These data are in accordance with the environmental parameters of survival in a modern tropical shallow water platform (T-factory). In particular, the sea surface temperature (SST) of a T-factory ranges from 18 degrees C to 30.5 degrees C representing respectively the minimum SST for the carbonate factory persistence and the maximum SST that a T-factory can tolerate

A method for measuring the Neel relaxation time in a frozen ferrofluid

We report a novel method of determining the average Neel relaxation time and its temperature dependence by calculating derivatives of the measured time dependence of temperature for a frozen ferrofluid exposed to an alternating magnetic field. The ferrofluid, composed of dextran-coated Fe3O4 nanoparticles (diameter 13.7 nm +/- 4.7 nm), was synthesized via wet chemical precipitation and characterized by x-ray diffraction and transmission electron microscopy. An alternating magnetic field of constant amplitude (H0 = 20 kA/m) driven at frequencies of 171 kHz, 232 kHz and 343 kHz was used to determine the temperature dependent magnetic energy absorption rate in the temperature range from 160 K to 210 K. We found that the specific absorption rate of the ferrofluid decreased monotonically with temperature over this range at the given frequencies. From these measured data, we determined the temperature dependence of the Neel relaxation time and estimate a room-temperature magnetocrystalline anisotropy constant of 40 kJ/m3, in agreement with previously published results

Vertical Profiles of Aerosol Optical Properties Over Central Illinois and Comparison with Surface and Satellite Measurements

Between June 2006 and September 2009, an instrumented light aircraft measured over 400 vertical profiles of aerosol and trace gas properties over eastern and central Illinois. The primary objectives of this program were to (1) measure the in situ aerosol properties and determine their vertical and temporal variability and (2) relate these aircraft measurements to concurrent surface and satellite measurements. Underflights of the CALIPSO satellite show reasonable agreement in a majority of retrieved profiles between aircraft-measured extinction at 532 nm (adjusted to ambient relative humidity) and CALIPSO-retrieved extinction, and suggest that routine aircraft profiling programs can be used to better understand and validate satellite retrieval algorithms. CALIPSO tended to overestimate the aerosol extinction at this location in some boundary layer flight segments when scattered or broken clouds were present, which could be related to problems with CALIPSO cloud screening methods. The in situ aircraft-collected aerosol data suggest extinction thresholds for the likelihood of aerosol layers being detected by the CALIOP lidar. These statistical data offer guidance as to the likelihood of CALIPSO's ability to retrieve aerosol extinction at various locations around the globe

Comment on 'Geoengineering with seagrasses: Is credit due where credit is given?'

Over the past decade scientists around the world have sought to estimate the capacity of seagrass meadows to sequester carbon, and thereby understand their role in climate change mitigation. The number of studies reporting on seagrass carbon accumulation rates is still limited, but growing scientific evidence supports the hypothesis that seagrasses have been efficiently locking away CO2 for decades to millennia (e.g. Macreadie et al 2014, Mateo et al 1997, Serrano et al 2012). Johannessen and Macdonald (2016), however, challenge the role of seagrasses as carbon traps, claiming that gains in carbon storage by seagrasses may be \u27illusionary\u27 and that \u27their contribution to the global burial of carbon has not yet been established\u27. The authors warn that misunderstandings of how sediments receive, process and store carbon have led to an overestimation of carbon burial by seagrasses. Here we would like to clarify some of the questions raised by Johannessen and Macdonald (2016), with the aim to promote discussion within the scientific community about the evidence for carbon sequestration by seagrasses with a view to awarding carbon credits

Ordered spin-ice state in the geometrically frustrated metallic-ferromagnet Sm2Mo2O7

The recent discovery of Spin-ice is a spectacular example of non-coplanar spin arrangements that can arise in the pyrochlore A2B2O7 structure. We present magnetic and thermodynamic studies on the metallic-ferromagnet pyrochlore Sm2Mo2O7. Our studies, carried out on oriented crystals, suggest that the Sm spins have an ordered spin-ice ground state below about T* = 15 K. The temperature- and field-evolution of the ordered spin-ice state are governed by an antiferromagnetic coupling between the Sm and Mo spins. We propose that as a consequence of a robust feature of this coupling, the tetrahedra aligned with the external field adopt a "1-in, 3-out" spin structure as opposed to "3-in, 1-out" in dipolar spin ices, as the field exceeds a critical value

Swelling of Transported Smoke from Savanna Fires over the Southeast Atlantic Ocean

We use the recently released Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) Version 4.1 (V4) lidar data to study the smoke plumes transported from Southern African biomass burning areas. Significant improvements in the CALIPSO V4 Level 1 calibration and V4 Level 2 algorithms lead to a better representation of their optical properties, with the aerosol subtype improvements being particularly relevant to smoke over this area. For the first time, we show evidence of smoke particles increasing in size, evidenced in their particulate color ratios, as they are transported over the South Atlantic Ocean from the source regions over Southern Africa. We hypothesize that this is due to hygroscopic swelling of the smoke particles and is reflected in the higher relative humidity in the middle troposphere for profiles with smoke. This finding may have implications for radiative forcing estimates over this area and is also relevant to the ORACLES field mission

Swelling of Transported Smoke from Savanna fires over the Southeast Atlantic Ocean

We use the recently released Version 4 (V4) lidar data products from CALIPSO to study the smoke plumes transported from Southern African biomass burning areas. The significant improvements in CALIPSO V4 Level 1 calibration and the V4 Level 2 aerosol subtyping algorithms, the latter being particularly relevant to biomass burning smoke over this area, lead to a better representation of their optical properties. For the first time, we show evidence of smoke particles increasing in size, evidenced in their particulate color ratios, as they are transported over the South Atlantic Ocean from the source regions over Southern Africa. This is likely due to hygroscopic swelling of the smoke particles and is reflected in the higher relative humidity in the middle troposphere for profiles with smoke. This finding may have implications for radiative forcing estimates over this area and is relevant to the ORACLES field mission that is currently underway