Postthrombotic or non-postthrombotic severe venous insufficiency: Impact of removal of superficial venous reflux with or without subcutaneous fasciotomy

BackgroundSevere chronic venous insufficiency is often associated with therapy-resistant or recurrent venous leg ulcers, either as a result of deep vein thrombosis (DVT)- (postthrombotic syndrome [PTS]) or superficial venous insufficiency (SVI). Frequently present dermatoliposclerosis affects the skin as well as the subcutaneous and subfascial structures, which may impact tissue pressures and compromise skin perfusion. This study was undertaken to measure tissue pressures in PTS and SVI limbs and to evaluate the impact of removal of superficial venous reflux with or without concomitant subcutaneous fasciotomy.MaterialIn eight patients with recurrent, therapy-resistant venous leg ulcers, due to PTS (11 limbs, 12 ulcers) and 14 patients with severe SVI (14 limbs, 14 ulcers), subcutaneous fasciotomy was performed in addition to removal of superficial reflux. They were compared with eight patients with PTS (11 limbs, 11 ulcers) and 10 patients with SVI (13 limbs, 13 ulcers) who did not have fasciotomy in addition to removal of their superficial venous reflux. Intramuscular (i.m.) and subcutaneous (s.c.) tissue pressures and transcutaneous oxygen tension (TcPO2) were measured prior to, immediately after, and 3 months following the surgical intervention. Healing of ulcer (spontaneous or by skin grafting) at 3 months was also observed.ResultsThere were no statistical differences between the groups regarding gender and age distribution or ulcer age at the time of surgery. All patients had in addition to surgery compression stockings class II (30 mm Hg). The i.m. tissue pressure was higher in patients with PTS compared with SVI patients, while s.c. tissue pressure and TcPO2 did not differ between the groups. When fasciotomy was performed, i.m. and s.c. tissue pressures decreased and TcPO2 increased significantly. Without fasciotomy, only s.c. tissue pressure decreased first at 3 months postoperatively. In the SVI-group, i.m tissue pressure was significantly decreased at 3 months in the group without fasciotomy.ConclusionsPatients with severe chronic venous insufficiency with therapy-resistant or recurrent ulcer disease due to deep and superficial insufficiency have higher i.m. tissue pressures than patients with only superficial venous reflux, even though both groups have higher i.m. and s.c. tissue pressures compared with normal values. Eradication of all superficial reflux lowers s.c. tissue pressure, while additional fasciotomy lowers both i.m. and s.c. tissue pressures and increases TcPO2, which seems to promote ulcer healing

Deep x-ray lithography for micromechanics

Extensions of the German LIGA process have brought about fabrication capability suitable for cost effective production of precision engineered components. The process attributes allow fabrication of mechanical components which are not capable of being made via conventional subtractive machining methods. Two process improvements have been responsible for this extended capability which involve the areas of thick photoresist application and planarization via precision lapping. Application of low-stress x-ray photoresist has been achieved using room temperature solvent bonding of a preformed photoresist sheet. Precision diamond lapping and polishing has provided a flexible process for the planarization of a wide variety of electroplated metals in the presence of photoresist. Exposure results from the 2.5 GeV National Synchrotron Light Source storage ring at Brookhaven National Laboratory have shown that structural heights of several millimeter and above are possible. The process capabilities are also well suited for microactuator fabrication. Linear and rotational magnetic microactuators have been constructed which use coil winding technology with LIGA fabricated coil forms. Actuator output forces of 1 milliNewton have been obtained with power dissipation on the order of milliWatts. A rotational microdynamometer system which is capable of measuring torque-speed data is also discussed

Characterizing changes in soybean spectral response curves with breeding advancements

Citation: Christenson, Brent S., William T. Schapaugh, Nan An, Kevin P. Price, and Allan K. Fritz. “Characterizing Changes in Soybean Spectral Response Curves with Breeding Advancements.” Crop Science 54, no. 4 (2014): 1585–97. https://doi.org/10.2135/cropsci2013.08.0575.Soybean (Glycine max (L.) Merr.) crop yield has steadily increased in the past 60 yr due in part to breeding advances. Relations between canopy spectral reflectance to specific plant functions may help characterize the impact of breeding on soybean cultivar development. The objectives of this study were to: 1) find specific regions of the soybean canopy spectral reflectance response curves that show genotypic differences; and 2) determine the effect of the breeding process on spectral reflectance response curves of soybean cultivars. Canopy spectral reflectance measurements were taken on 20 maturity group III (MGIII) and 20 maturity group IV (MGIV) soybean cultivars ranging in release year from 1923 to 2010 (arranged in a randomized complete block design) in 2011 and 2012 in Manhattan, KS. Large genotypic differences were found among cultivars, especially in the green (500 nm–600 nm), red (600 nm–700 nm), and red-edge (700nm–730 nm) portions of the spectra. Reflectance in the visible (VIS) (400–700 nm), red-edge (700–730 nm), and near-infrared (NIR) (730–1305) portions of the spectra varied with year of release (YOR) among cultivars. The more recently released cultivars tended to have lower reflectance values in the VIS and red-edge spectra portions and higher values in the NIR portion of the spectra than earlier-released cultivars. Results also indicate that spectral reflectance in the NIR portion of the spectra are highly confounded with maturity and other agronomic traits. These results indicate that breeding advancement has had an impact on canopy spectral reflectance curves and the VIS and red-edge portions of the spectra may be a source of variation for further cultivar development and advancement

Fabrication of MEMS Devices by Powder-Filling into DXRL-Formed Molds

We have developed a variety of processes for fabricating components for micro devices based on deep x-ray lithography (DXRL). Although the techniques are applicable to many materials, we have demonstrated them using hard (Nd{sub 2}Fe{sub 14}B) and soft (Ni-Zn ferrite) magnetic materials because of the importance of these materials in magnetic micro-actuators and other devices and because of the difficulty fabricating them by other means. The simplest technique involves pressing a mixture of magnetic powder and a binder into a DXRL-formed mold. In the second technique, powder is pressed into the mold and then sintered to densify. The other two processes involve pressing at high temperature either powder or a dense bulk material into a ceramic mold that was previously made using a DXRL mold. These techniques allow arbitrary 2-dimensional shapes to be made 10 to 1000 micrometers thick with in-plane dimensions as small as 50 micrometers and dimensional tolerances in the micron range. Bonded isotropic Nd{sub 2}Fe{sub 14}B micromagnets made by these processes had an energy product of 7 MGOe

Planar rotational magnetic micromotors with integrated shaft encoder and magnetic rotor levitation

Deep x-ray lithography and electroplating may be combined to form a fabrication tool for micromechanical devices with large structural heights, to 500 micron, and extreme edge acuities, less than 0.1 micron-run-out per 100 micron of height. This process concept which originated in Germany as LIGA may be further extended by adding surface micromachining. This extension permits the fabrication of precision metal and plastic parts which may be assembled into three-dimensional micromechanical components and systems. The processing tool may be used to fabricate devices from ferromagnetic material such as nickel and nickel-iron alloys. These materials when properly heat treated exhibit acceptable magnetic behavior for current to flux conversion and marginal behavior for permanent magnet applications. The tool and materials have been tested via planar, magnetic, rotational micromotor fabrication. Three phase reluctance machines of the 6:4 configuration with 280 micron diameter rotors have been tested and analyzed. Stable rotational speeds to 34,000 rpm with output torques above 10 x 10(exp -9) N-m have been obtained. The behavior is monitored with integrated shaft encoders which are photodiodes which measure the rotor response. Magnetic levitation of the rotor via reluctance forces has been achieved and has reduced frictional torque losses to less than 1 percent of the available torque. The results indicate that high speed limits of these actuators are related to torque ripple. Hysteresis motors with magnetic bearings are under consideration and will produce high speed rotational machines with excellent sensor application potential

Identification of Quantitative Trait Loci Affecting Female Reproductive Traits in a Multigeneration Meishan-White Composite Swine Population

A multigeneration crossbred Meishan- White composite resource population was used to identify quantitative trait loci (QTL) for age at first estrus (AP) and the components of litter size: ovulation rate (OR; number of ova released in an estrous period) and uterine capacity (UC). The population was established by reciprocally mating Meishan (ME) and White composite (WC) pigs. Resultant F1 females were mated to either ME or WC boars to produce backcross progeny (BC) of either ¾ WC ¼ ME or ¼ WC ¾ ME. To produce the next generation (F3) , ¾ WC ¼ ME animals were mated to ¼ WC ¾ ME animals yielding half-blood (½ WC ½ ME) progeny. A final generation (F4) was produced by inter se mating F3 animals. Measurements for AP and OR were recorded on 101 BC, 389 F3, and 110 F4 gilts, and UC data were from 101 BC and 110 F4 first parity litters. A genomic scan was conducted with markers (n = 157) spaced &#;20 cM apart. All parental, F1, BC, and F4 animals but only 84 F3 animals were genotyped and included in this study. The QTL analysis fitted a QTL at 1-cM intervals throughout the genome, and QTL effects were tested using approximate genome-wide significance levels. For OR, a significant (E[false positive] \u3c .05) QTL was detected on chromosome 8, suggestive (E[false positive] \u3c 1.0) QTL were detected on chromosomes 3 and 10, and two additional regions were detected that may possess a QTL (E[false positive] \u3c 2.0) on chromosomes 9 and 15. Two regions possessed suggestive evidence for QTL affecting AP on chromosomes 1 and 10, and one suggestive region on chromosome 8 was identified for UC. Further analyses of other populations of swine are necessary to determine the extent of allelic variation at the identified QTL

Heat to Electricity Conversion by a Graphene Stripe with Heavy Chiral Fermions

A conversion of thermal energy into electricity is considered in the electrically polarized graphene stripes with zigzag edges where the heavy chiral fermion (HCF) states are formed. The stripes are characterized by a high electric conductance Ge and by a significant Seebeck coefficient S. The electric current in the stripes is induced due to a non-equilibrium thermal injection of "hot" electrons. This thermoelectric generation process might be utilized for building of thermoelectric generators with an exceptionally high figure of merit Z{\delta}T \simeq 100 >> 1 and with an appreciable electric power densities \sim 1 MW/cm2.Comment: 8 pages, 3 figure