Observation of Fermi pressure in a gas of trapped atoms

We report the attainment of simultaneous quantum degeneracy in a mixed gas of bosons (lithium-7) and fermions (lithium-6). The Fermi gas has been cooled to a temperature of 0.25 times the Fermi temperature by thermal collisions with the evaporatively cooled bosons. At this temperature, the spatial size of the gas is strongly affected by the Fermi pressure resulting from the Pauli exclusion principle and gives clear experimental evidence for quantum degeneracy.     

Experimental snowpack reduction alters organic matter and net N mineralization potential of soil macroaggregates in a northern hardwood forest

Climate change is predicted to reduce or delay annual wintertime snow pack formation in the forests of the northeastern US. Any delay in snowpack formation could increase soil freezing in winter and, thereby, alter soil characteristics and processes. We examined the hypothesis that delayed snowpack would disrupt soil structure and change organic matter bioavailability in an experimental snow removal study at the Hubbard Brook Experimental Forest (HBEF), NH, USA. Pairs of reference and snow removal treatment plots were studied in four different sites at HBEF. Snow was removed from November–January of two winters, inducing soil freezing throughout both winters. Size class distribution and organic matter concentration and content of aggregates, and carbon and nitrogen mineralization potential of size fractions were quantified for surface mineral soils in the spring of both years immediately after snowmelt. In the first year of sampling, the only significant effect of snow removal was an increase in the smallest (<53 μm) size fraction of mineral soil. In the second year, snow removal increased organic matter concentrations of macroaggregate (250–2,000 μm) and microaggregate (53–250 μm) size fractions. This change corresponded to an increase in net N mineralization potential and the ratio of N to C mineralized in the macroaggregate fraction, but there were no effects of snow removal on C mineralization. We propose that soil freezing increases the movement of organic matter from organic to mineral soil horizons and increases the N content of mineralizable substrates in mineral soil following years with delayed snowpack formation.     

Transcutaneous tibial implants: a surgical procedure for restoring ambulation after amputation of the distal aspect of the tibia in a dog

Objective— To report surgical planning, technique, and long-term outcome of custom transcutaneous tibial implants used to restore ambulation after bilateral pelvic limb amputation in a dog.
Study Design— Case report.
Animals— A 4-year-old, 25.5 kg, female spayed, Siberian Husky.
Methods— Computed tomographic scans of the pelvic limbs were used to build sterolithographic models of the remaining tibia after bilateral amputation of the distal aspect of the tibiae. The sterolithographic models facilitated fabrication of implants that would replace the missing distal segments of the tibiae. Custom implants were surgically placed in both limbs.
Results— Assisted ambulation was restored immediately postoperatively and unassisted locomotion occurred at 7 days. At 14 months, aseptic loosening of the right implant occurred, it was removed and a 2nd transcutaneous implant was fabricated and implanted. At 26 months after initial surgery and 17 months after revision of the right implant, function is restored at a walk, trot, and run.
Conclusion— Based on over a 2-year follow-up, transcutaneous tibial implants allowed for restoration of locomotion.
Clinical Relevance— Transcutaneous tibial implants offer a potentially viable treatment option for restoring ambulation after amputation of the distal aspect of the tibiae in the dog.     

Rehabilitation of companion animals following orthopaedic surgery

ABSTRACT

Physical therapy and rehabilitation following orthopaedic surgery in companion animals have become more common and new advancements in this field have been made in recent years. Surgery alone may not return the animal to its previous physical activity or work-related tasks, whether due to concurrent soft tissue trauma, arthrogenic muscle inhibition or osteoarthritis. Rehabilitation therapies following surgery can restore function as well as strength, coordination and balance. Many simple techniques such as cryotherapy and passive range of motion exercises have been shown to improve outcomes following musculoskeletal procedures and may help restore function as well as reduce pain and facilitate healing. Some techniques are more useful during different stages in order to achieve optimum tissue healing and recovery of function. During the first 72 hours, rehabilitation should focus on reduction of inflammation and pain, maintaining joint nutrition and range of motion, and stimulating vascularisation and healing; and may include cryotherapy, passive range of motion exercises, massage and therapeutic exercises. Following the initial recovery period, the goals of rehabilitation also include restoring strength, balance and normal gait patterns, as well as recovery of function. During this period the focus of therapy may shift toward therapeutic exercises, aquatic therapy and increasing activity in the animal. Therapeutic modalities such as neuromuscular electrical stimulation, photobiomodulation (laser therapy), therapeutic ultrasound and extracorporeal shock wave therapy have been reported to reduce pain and inflammation, enhance healing and reduce recovery time in the early and late stages following orthopaedic surgery.