Irrigation Scheduling Based on Wireless Sensors Output and Soil-Water Characteristic Curve in Two Soils.

Data-driven irrigation planning can optimize crop yield and reduce adverse impacts on surface and ground water quality. We evaluated an irrigation scheduling strategy based on soil matric potentials recorded by wireless Watermark (WM) sensors installed in sandy loam and clay loam soils and soil-water characteristic curve data. Five wireless WM nodes (IRROmesh) were installed at each location, where each node consisted of three WM sensors that were installed at 15, 30, and 60 cm depths in the crop rows. Soil moisture contents, at field capacity and permanent wilting points, were determined from soil-water characteristic curves and were approximately 23% and 11% for a sandy loam, and 35% and 17% for a clay loam, respectively. The field capacity level which occurs shortly after an irrigation event was considered the upper point of soil moisture content, and the lower point was the maximum soil water depletion level at 50% of plant available water capacity in the root zone, depending on crop type, root depth, growth stage and soil type. The lower thresholds of soil moisture content to trigger an irrigation event were 17% and 26% in the sandy loam and clay loam soils, respectively. The corresponding soil water potential readings from the WM sensors to initiate irrigation events were approximately 60 kPa and 105 kPa for sandy loam, and clay loam soils, respectively. Watermark sensors can be successfully used for irrigation scheduling by simply setting two levels of moisture content using soil-water characteristic curve data. Further, the wireless system can help farmers and irrigators monitor real-time moisture content in the soil root zone of their crops and determine irrigation scheduling remotely without time consuming, manual data logging and frequent visits to the field.

Role of heparan sulfate as a tissue-specific regulator of FGF-4 and FGF receptor recognition.

FGF signaling uses receptor tyrosine kinases that form high-affinity complexes with FGFs and heparan sulfate (HS) proteoglycans at the cell surface. It is hypothesized that assembly of these complexes requires simultaneous recognition of distinct sulfation patterns within the HS chain by FGF and the FGF receptor (FR), suggesting that tissue-specific HS synthesis may regulate FGF signaling. To address this, FGF-2 and FGF-4, and extracellular domain constructs of FR1-IIIc (FR1c) and FR2-IIIc (FR2c), were used to probe for tissue-specific HS in embryonic day 18 mouse embryos. Whereas FGF-2 binds HS ubiquitously, FGF-4 exhibits a restricted pattern, failing to bind HS in the heart and blood vessels and failing to activate signaling in mouse aortic endothelial cells. This suggests that FGF-4 seeks a specific HS sulfation pattern, distinct from that of FGF-2, which is not expressed in most vascular tissues. Additionally, whereas FR2c binds all FGF-4-HS complexes, FR1c fails to bind FGF-4-HS in most tissues, as well as in Raji-S1 cells expressing syndecan-1. Proliferation assays using BaF3 cells expressing either FR1c or FR2c support these results. This suggests that FGF and FR recognition of specific HS sulfation patterns is critical for the activation of FGF signaling, and that synthesis of these patterns is regulated during embryonic development.

Right on track? Performance of satellite telemetry in terrestrial wildlife research.

Satellite telemetry is an increasingly utilized technology in wildlife research, and current devices can track individual animal movements at unprecedented spatial and temporal resolutions. However, as we enter the golden age of satellite telemetry, we need an in-depth understanding of the main technological, species-specific and environmental factors that determine the success and failure of satellite tracking devices across species and habitats. Here, we assess the relative influence of such factors on the ability of satellite telemetry units to provide the expected amount and quality of data by analyzing data from over 3,000 devices deployed on 62 terrestrial species in 167 projects worldwide. We evaluate the success rate in obtaining GPS fixes as well as in transferring these fixes to the user and we evaluate failure rates. Average fix success and data transfer rates were high and were generally better predicted by species and unit characteristics, while environmental characteristics influenced the variability of performance. However, 48% of the unit deployments ended prematurely, half of them due to technical failure. Nonetheless, this study shows that the performance of satellite telemetry applications has shown improvements over time, and based on our findings, we provide further recommendations for both users and manufacturers.

Soil and surface runoff phosphorus relationships for five typical USA midwest soils.

Excessively high soil P can increase P loss with surface runoff. This study used indoor rainfall simulations to characterize soil and runoff P relationships for five Midwest soils (Argiudoll, Calciaquaoll, Hapludalf, and two Hapludolls). Topsoil (15-cm depth, 241-289 g clay kg(-1) and pH 6.0-8.0) was incubated with five NH4H2PO4 rates (0-600 mg P kg(-1)) for 30 d. Total soil P (TPS) and soil-test P (STP) measured with Bray-P1 (BP), Mehlich-3 (M3P), Olsen (OP), Fe-oxide-impregnated paper (FeP), and water (WP) tests were 370 to 1360, 3 to 530, 10 to 675, 4 to 640, 7 to 507, and 2 to 568 mg P kg(-1), respectively. Degree of soil P saturation (DPS) was estimated by indices based on P sorption index (PSI) and STP (DPSSTP) and P, Fe, and Al extracted by ammonium oxalate (DPSox) or Mehlich-3 (DPSM3). Soil was packed to 1.1 g cm(-3) bulk density in triplicate boxes set at 4% slope. Surface runoff was collected during 75 min of 6.5 cm h(-1) rain. Runoff bioavailable P (BAP) and dissolved reactive P (DRP) increased linearly with increased P rate, STP, DPSox, and DPSM3 but curvilinearly with DPSSTP. Correlations between DRP or BAP and soil tests or saturation indices across soils were greatest (r > or = 0.95) for FeP, OP, and WP and poorest for BP and TPS (r = 0.83-0.88). Excluding the calcareous soil (Calciaquoll) significantly improved correlations only for BP. Differences in relationships between runoff P and the soil tests were small or nonexistent among the noncalcareous soils. Routine soil P tests can estimate relationships between runoff P concentration and P application or soil P, although estimates would be improved by separate calibrations for calcareous and noncalcareous soils.

Purification of malic enzyme from Ascaris suum using NAD+-agarose.

Malic enzyme has been purified from Ascaris suum by polyethylene glycol precipitation, ion-exchange chromatography, ammonium sulfate precipitation, and NAD-agarose affinity chromatography to a specific activity of 80 units/mg (V/[E]t = 350 s-1). The preparation was shown to be homogeneous by SDS polyacrylamide disc gel electrophoresis. The procedure can be accomplished in a maximum of four days with a 74% yield.

Purification and characterization of phosphorylase B from Ascaris suum.

Glycogen phosphorylase b (EC 2.4.1.1) has been purified from the muscle of the roundworm, Ascaris suum. The 223-fold purified enzyme was shown to be homogenous by high performance liquid chromatography (HPLC), gel filtration column chromatography and sodium dodecyl sulfate (SDS) gel electrophoresis. The apparent native molecular weight of the enzyme determined by size exclusion chromatography by HPLC and gel filtration corresponded to 200 000 and 199 000, respectively. The subunit molecular weight of the enzyme was determined to be 100 000 by electrophoresis in the presence of SDS. Therefore, the enzyme appears to be a dimer with identical or near identical subunits. The enzyme contained 1 mol of pyridoxal 5'-phosphate per mol subunit and exhibited an absorbance index E1% 280 of 13.8. The apparent isoelectric point of the enzyme is 5.53. The enzyme, inactive in the absence of AMP, can be converted to the active form by rabbit muscle phosphorylase kinase and MgATP. The molecular weight of the activated form of the enzyme is 200 000. Kinetic studies showed apparent Km values of 0.17% for glycogen, 36 mM for Pi and 52 mM for glucose-1-P. The apparent Ka for AMP was 0.22 mM.

Vascular injuries associated with dislocation of the knee.

Two hundred and forty-five knee dislocations were analyzed including forty-one new cases. The high incidence of injuries to the popliteal artery that accompanies this lesion (32 per cent) was confirmed, and it was re-emphasized that vascular repair must be completed within six or at the most eight hours from the time of injury to avoid amputation. Of the patients not treated within that time period, 86 per cent had an amputation and two-thirds of the remaining 14 per cent had ischemic changes.

Neurologic injuries with the Galveston technique of L-rod instrumentation for scoliosis.

A group of surgeons who used the Galveston technique for L-rod instrumentation (LRI) were surveyed to learn their experience with associated neurologic injuries. Among 507 LRIs for scoliosis there were two partial cord syndromes (0.4%), 13 "nerve root hyperesthesias" (2.6%), and two other nerve injuries (0.4%). All patients, except one with mild residuals after a partial cord injury, fully recovered from their neurologic problem. Experience in spinal surgery, education about LRI strategies and techniques, hands-on technical instruction, and use of an established process for LRI are believed to be the factors that enabled these surgeons to perform this complex procedure with relative safety.

The Galveston technique of pelvic fixation with L-rod instrumentation of the spine.

From April 1978 to October 1982, the authors performed 44 pelvic fixations as part of L-rod instrumentation of a spinal deformity. Thirty scoliosis and revision scoliosis cases with a minimum of 1 year follow-up were analyzed for changes of the instrumentation with respect to the pelvis, angular changes at the lumbosacral junction, radiolucency about the portions of the rods providing pelvic fixation, and success of lumbosacral fusion. The technique for fixation was different among three groups of patients. A pelvic fixation technique in which the pelvic segments of the rods were longer than 6 cm, completely intraosseous through their iliac course, and within 1.5 cm of the sciatic notch, yielded the best results.

Design and evaluation of a posterior laminar clamp spinal fixation system.

A new spinal instrumentation system for posterior applications was designed with the intent of minimizing intrusion of hardware into the neural canal during and postinsertion. Basic biomechanical measurements of posterior pullout strength led to the establishment of a clamp as an effective mechanism for gaining purchase on the vertebral lamina. These experiments defined the appropriate instrumentation size, as well as establishing that there was no loss of strength with the spinous process removed and the posterior laminar cortex compromised. There was no statistically significant difference between the maximum pullout strength achievable, using a band around the lamina as a control, and that produced by the implant system, in the thoracic spine. Comparative testing of a prototype system in flexion, extension, lateral bending, and torsion showed that the system, in general, had stiffness greater than segmental wiring and less than or equal to Cotrel-Dubousset fixation.

A biomechanical study of thoracolumbar spinal fractures with bone in the canal. Part I. The effect of laminectomy.

A simulation of thoracolumbar spinal fractures with bone in the canal was performed using fresh cadaver spines. In the study, a hole was drilled anterior to posterior in vertebral body T12 to accommodate a microload cell and displacement transducer that was then manually pushed into the canal to simulate the compressive effect of retropulsed bone on the spinal cord. In this part of the study, measurements were made pre- and postlaminectomy. The results indicated that laminectomy had no decompressive effect with up to 35% occlusion of the canal. Measurements of dural wall deflection during penetration of the load cell indicated that the anterior wall deformed locally due to penetration of the load cell with minimal displacement of the posterior wall occurring.

A biomechanical study of thoracolumbar spine fractures with bone in the canal. Part III. Mechanical properties of the dura and its tethering ligaments.

Experiments were performed to determine some mechanical properties of the spinal cord-meningeal (SCM) complex and its tethering elements with reference to factors contributing to contact pressure of an anterior mass on the SCM complex with spinal fracture and the development of some means to relieve the pressure. Measurements were made using a combined microload cell and displacement transducer that was passed posteriorly through a hole drilled in vertebra T12 through the interpedicular space and contacted the cord. Loss of nerve roots and anterior ligaments as dural tethers in the lumbar region permitted the SCM complex to fall out of the lordosis of the canal and fail to resist transverse loading. Head and neck flexion increased contact force for a given depth of penetration, particularly in the cervical region. This was consistent with measurements of strain along the dura that was greatest in the cervical region. The dura was found to be elastic, having a failure strain averaging 34% but was uniform in thickness, stiffness, and elastic modulus along its length. The study did not delineate any surgical manipulation other than removal of the anterior mass that would be beneficial when there is anterior compression of the spinal cord.

A biomechanical study of thoracolumbar spinal fractures with bone in the canal. Part II. The effect of flexion angulation, distraction, and shortening of the motion segment.

In the second part of this biomechanical study of thoracolumbar spinal fractures with bone in the neural canal contract force on the spinal cord--meningeal complex was measured with relation to varying fracture wedge depth, flexion angulations, and distraction and shortening of the fracture model motion segment. The removal of progressively deeper vertebral body wedges did not change the measured contact force/depth of penetration characteristics, however, the resistance to flexion angulation was decreased. Distraction of the motion segment an average of 5.2 mm increased significantly the contact force at the same depth of penetration compared with the case of normal vertebral body height. Shortening an average of 3.2 mm did not have a significant effect. Flexion angulation to 20 degrees did not change the depth/force characteristic in either the shortened or distracted case.

Rib regeneration area as an indicator of fusion area in adolescent idiopathic scoliosis.

This retrospective study of 24 patients with adolescent idiopathic scoliosis who underwent L-rod instrumentation, posterior thoracoplasty, and rib-bone grafting analyzed the correlation between the quality of rib regeneration and the host response to the rib-bone grafts. A planimetric technique was used to quantitate the coronal plane area of the resected ribs and of an L1-L2 concave fusion area immediately after surgery and at the end of the first postsurgical year. Using computerized regression analysis, these and other variables such as age, Cobb angle, and grafting technique were studied. Rib regeneration correlated with spinal fusion but not with age or Cobb angle. A better host response with strip vs. morseled graft was suggested, but not statistically proven. The data strongly support the belief that systemic biologic factors are a major variable affecting the quality of the fusion procedure.

The biomechanics of decompressive laminectomy.

The biomechanical effect of laminectomy as a means of relieving compression of the spinal cord-meningeal complex by an anterior mass was studied in ten grossly normal human cadaver spines. The basic experimental set-up involved drilling a sagittal plane hole transversely across a vertebral body to provide direct access to the anterior aspect of the neural canal. After securing a probe and linearly variable differential transformer (LVDT) assembly at each site to be tested, the probe was gently pushed into the neural canal; contact force against the tip of the probe as well as the depth of probe penetration was measured and recorded. Laminectomy did not alter the resulting contact force/anterior penetration plots at the fifth cervical, seventh thoracic, 12th thoracic, or third lumbar vertebra. Using the probe/LVDT assembly to measure anterior dural displacement and a cantilever displacement device to measure posterior dural displacement after laminectomy at the 12th thoracic vertebra, the authors found that although the anterior dura underwent gross displacement as the probe was pushed into the neural canal, the posterior dura displaced to a minimal degree. The extent of the laminectomy was not a factor. The study did not demonstrate any possible mechanism by which laminectomy could reduce the pressure exerted on the dura and neural elements by an anterior mass in a spine with otherwise normal neural canal dimensions.

Biomechanical comparisons of spinal fracture models and the stabilizing effects of posterior instrumentations.

In this study, the authors evaluated the stiffness of motion segments in intact spines in two spine fracture models, and with each of five implant systems used for posterior fixation of thoracolumbar spine fractures. The devices represented a cross-section of types, including those employing sublaminar wires with and without laminar hooks, pedicle screws, plates, and rods. Two spine fracture models, one partially and one totally destabilized, were used in the tests of the instrumentation. Stiffness, or the magnitude of load needed to produce a unit displacement of the construct in the direction of the applied load, was measured in flexion, extension, lateral bending, and torsion in combination with a compressive force. Both horizontal plane shear and angular displacements were measured in the two fracture patterns. All evaluations were made by testing the difference in stiffness for statistical significance among groups. The results showed significant differences in stiffness without instrumentation among intact spines, partly destabilized spines (anterior two-thirds of disk and posterior ligaments removed), and totally destabilized spines (only anterior longitudinal ligament intact). The implant/spine constructs were least stiff relative to the intact spine in torsion, followed in increasing order of stiffness with flexion, lateral bending, and extension. In the Roy-Camille plate with six-screw fixation was found to produce the stiffest construct, followed by wired Harrington rods, C-rods and J-rods, and the Vermont internal fixator.(ABSTRACT TRUNCATED AT 250 WORDS)

A mechanistic classification of closed, indirect fractures and dislocations of the lower cervical spine.

Closed, indirect fractures and dislocations of the lower cervical spine occur in families or groups within which there is a spectrum of anatomic damage to a cervical motion segment. This study of 165 cases demonstrates the various spectra of injury, called phylogenies, and develops a classification based on the mechanism of injury. The common groups are compressive flexion, vertical compression, distractive flexion, compressive extension, distractive extension, and lateral flexion. The probability of an associated neurologic lesion relates directly to the type and severity of cervical spine injury. With use of the classification, it is possible to formulate a rational treatment plan for injuries to the cervical spine.

Topics of interest in pediatric orthopedics.

This two-in-one article presents an overview of septic arthritis of the hip and school screening for adolescent idiopathic scoliosis--two problems commonly shared by the pediatrician and the pediatric orthopedic surgeon. The importance of aggressive diagnostic measures and treatment for the septic hip is emphasized and the basis for the rationale is given. In the section on scoliosis, the reader is introduced to the "scoliometer," and a rationale for management of most of these children by the primary physician is given.

The immature goat as an animal model for Legg-Calvé-Perthes disease.

Legg-Calvé-Perthes disease (LCPD) results from avascular necrosis of the capital femoral epiphysis in growing children. This disease often yields a significant deformity of the proximal femur, which may result in osteoarthritis. Its cause is unknown, although extensive radiographic, clinical, and histologic evaluations have been performed. Attempts at developing an animal model for LCPD have been unsuccessful. Previous models have been based predominantly on determining the vascular etiology of the disease. There is a need for an animal model that mimics the growth pattern of the proximal femur seen in LCPD. Such a model would allow for the development and testing of new treatments. Thus far, no treatment strategy has been completely successful. A study involving graphic analysis of radiographs found that arrested anterolateral physeal growth with continued or accelerated perichondrial ring and posteromedial epiphyseal growth would account for the most severe morphologic changes observed in the femoral heads of patients with LCPD. A surgical procedure was performed to ablate the capital femoral physis in goat kids in an attempt to mimic the changes noted in this study. The procedure was evaluated with radiographs, gross specimens, and histopathologic slides. Graphic analysis of the radiographs revealed changes in the shape of the operated femoral head compared with the unoperated femoral head. While bone, fibrous, and fibrocartilaginous bridges were histologically observed across the physis, the resultant deformities did not mimic the changes identified in the graphic analysis study, perhaps because of inconsistencies in the surgical ablative techniques, which will require further modification. This study provides the basis for further research to develop a successful model.

Growth profiles and articular cartilage characterization in a goat model of Legg-Calve-Perthes disease.

Numerous animal species, including the goat, have been evaluated as potential models for human Legg-Calve-Perthes disease (LCPD). These models disrupt the vasculature of the femoral head, causing it to collapse, and therefore do not mimic all the clinical patterns of the human disease. Baseline data regarding the weight and femoral length in the growing goat are not available. This study characterized the goat's normal growth for comparison with that of humans. The growth aberrations in the proximal femur created by surgically ablating the capital physis were described and compared with the aberrations observed in human LCPD cases. Age, weight, and femoral length (test and control) data were obtained for goats approximately 1 to 14 months of age. At 4 months of age, a craniolateral surgical approach was used to expose the cranial lateral capital physis so that it could be cauterized. Postoperative radiographs were evaluated by graphic analysis to assess the resultant changes in the morphology of the proximal femur. The articular cartilage of the femoral head and acetabulum was evaluated mechanically, using indentation testing, to determine the apparent modulus of elasticity, and histopathologically regarding its thickness and proteoglycan content. The proximal femurs of goats and humans exhibit similar morphology and growth patterns. There was a positive correlation between age, weight, and femoral lengths in the goat. The surgical procedure was effective in ablating the capital femoral physis as indicated by shorter femoral lengths and fragmented, flattened, and mushroomed femoral heads. The histopathological data revealed that the articular cartilage was significantly thicker in the operated hip joints at the ventrocaudal and cranial acetabula and the dorsal and ventral femoral heads. The test cartilage exhibited significantly less positive staining for proteoglycans in the dorsocaudal and the cranial acetabula as well as the ventral femoral head. The apparent modulus of elasticity, of the test cartilage was significantly lower than the control value at the dorsocaudal acetabulum. These data show that the surgical procedure produced morphological changes that mimic those in human LCPD. The increased thickness of the articular cartilage of the LCPD femoral head may account for the articular degeneration observed in older patients with LCPD, as increased cartilage thickness is associated with decreased tissue quality.