Dose perturbation effect of metallic spinal implants in proton beam therapy

The purpose of this study was to investigate the effect of dose perturbations for two metallic spinal screw implants in proton beam therapy in the perpendicular and parallel beam geometry. A 5.5 mm (diameter) by 45 mm (length) stainless steel (SS) screw and a 5.5 mm by 35 mm titanium (Ti) screw commonly used for spinal fixation were CT-scanned in a hybrid phantom of water and solid water. The CT data were processed with an orthopedic metal artifact reduction (O-MAR) algorithm. Treatment plans were generated for each metal screw with a proton beam oriented, first parallel and then perpendicular, to the longitudinal axis of the screw. The calculated dose profiles were compared with measured results from a plane-parallel ion chamber and Gafchromic EBT2 films. For the perpendicular setup, the measured dose immediately downstream from the screw exhibited dose enhancement up to 12% for SS and 8% for Ti, respectively, but such dose perturbation was not observed outside the lateral edges of the screws. The TPS showed 5% and 2% dose reductions immediately at the interface for the SS nd Ti screws, respectively, and up to 9% dose enhancements within 1 cm outside of the lateral edges of the screws. The measured dose enhancement was only observed within 5 mm from the interface along the beam path. At deeper depths, the lateral dose profiles appeared to be similar between the measurement and TPS, with dose reduction in the screw shadow region and dose enhancement within 1–2 cm outside of the lateral edges of the metals. For the parallel setup, no significant dose perturbation was detected at lateral distance beyond 3 mm away from both screws. Significant dose discrepancies exist between TPS calculations and ion chamber and film measurements in close proximity of high-Z inhomogeneities. The observed dose enhancement effect with proton therapy is not correctly modeled by TPS. An extra measure of caution should be taken when evaluating dosimetry with spinal metallic implants

Relationship between Carotid Artery Sclerosis and Blood Pressure Variability in Essential Hypertension Patients

Objectives: This study aimed to investigate the relationship between the presence of carotid arteriosclerosis (CAS) and blood pressure variability (BPV) in patients with essential hypertension. Methods: One hundred and forty four essential hypertension patients underwent ambulatory BP monitoring for 24 hours after hospitalization. Common BPV metrics were calculated. General clinical parameters, including age, gender, height, weight, history of coronary heart disease, stroke, diabetes, hypertension, smoking and drink, were recorded. Biochemical indices were obtained from a blood test. Carotid intima-media thickness (IMT) and carotid plaques were assessed to separate patients into a non-CAS group (IMT≤0.9 mm; n=82) and a CAS group (IMT>0.9 mm; n=62). BPV metrics and clinical parameters were analyzed and compared between the two groups. Multivariate logistic regression analysis was performed to determine the associated risk factors of CAS. Results: Multivariate logistic regression analysis revealed that two BPV metrics, the standard deviation of daytime systolic blood pressure (SSD) (OR: 1.587, 95%CI: 1.242–2.028), the difference between average daytime SBP and nighttime SBP (OR: 0.914, 95%CI: 0.855-0.977), as well as three clinical parameters (age, OR: 1.098, 95%CI: 1.034-1.167; smoking, OR: 4.072, 95%CI: 1.466–11.310, and fasting blood glucose, OR: 2.029, 95%CI: 1.407–2.928), were significant factors of CAS in essential hypertension patients. Conclusion: SSD, in combination with the ageing, smoking and FBG, has been identified as risk factors for CAS in patients with essential hypertension

Cell and matrix response of temporomandibular cartilage to mechanical loading

OBJECTIVES: The generation of transgenic mice expressing green fluorescent proteins (GFPs) has greatly aided our understanding of the development of connective tissues such as bone and cartilage. Perturbation of a biological system such as the temporomandibular joint (TMJ) within its adaptive remodeling capacity is particularly useful in analyzing cellular lineage progression. The objectives of this study were to determine: (i) if GFP reporters expressed in the TMJ indicate the different stages of cell maturation in fibrocartilage and (ii) how mechanical loading affects cellular response in different regions of the cartilage. DESIGN/METHODS: Four-week-old transgenic mice harboring combinations of fluorescent reporters (Dkk3-eGFP, Col1a1(3.6 kb)-GFPcyan, Col1a1(3.6 kb)-GFPtpz, Col2a1-GFPcyan, and Col10a1-RFPcherry) were used to analyze the expression pattern of transgenes in the mandibular condylar cartilage (MCC). To study the effect of TMJ loading, animals were subjected to forced mouth opening with custom springs exerting 50 g force for 1 h/day for 5 days. Dynamic mineralization and cellular proliferation (EdU-labeling) were assessed in loaded vs control mice. RESULTS: Dkk3 expression was seen in the superficial zone of the MCC, followed by Col1 in the cartilage zone, Col2 in the prehypertrophic zone, and Col10 in the hypertrophic zone at and below the tidemark. TMJ loading increased expression of the GFP reporters and EdU-labeling of cells in the cartilage, resulting in a thickness increase of all layers of the cartilage. In addition, mineral apposition increased resulting in Col10 expression by unmineralized cells above the tidemark. CONCLUSION: The TMJ responded to static loading by forming thicker cartilage through adaptive remodeling

Efficient Management of Water Resources for Improving the Livelihoods through Integrated Watershed Management Approach

Southwest China, administratively covering the provinces of Yunnan, Guizhou, Sichuan, Chongqing Municipality, and Tibet Autonomous Region is characterized by mountainous topography, multi-ethnic residents, and poor eco-environmental conditions. Except some parts of Sichuan province, the rest of the region consists of hills and mountains, which occupy more than 90 percent of the land area. Therefore, the cultivated land is very scarce. Most of the non-cultivated as well as cultivated lands are subject to severe soil erosion. Agriculture is a major dependency of livelihoods for the majority of the people in the region, especially in Yunnan, Guizhou and Sichuan provinces. The annual rainfall in this region varies from 1000 to 2000 mm and its distribution is erratic causing frequent droughts because most of the cropping is rain-fed. Agriculture is also the major source of revenues in the river valley areas in the southwest China, with a 44 percent of the social production values, and 54 percent of the Gross Domestic Product (GDP). Watershed management is one of the important schemes of the Chinese Government in the West Development Strategy. Economic development and improvement of eco-environmental conditions are two main goals of this strategy. The major constraints in this region are severe soil erosion, water scarcity for crop production and land degradation. The National Agricultural Research System (NARS) of China in recent years have developed and evaluated technologies like vegetation restoration, rain water harvesting, and control of soil erosion by different interventions in the research station to overcome the constraints. Since 2003 a collaborative project between International Crop Research Institute for Semi-Arid Tropics (ICRISAT) and Yunnan Academy of Agricultural Sciences (YAAS) and Guizhou Academy of Agricultural Sciences (GAAS), funded by Asian Development Bank (ADB), is being implemented in two benchmark watersheds representing two eco-regions, hot-arid valley region in Yunnan province and Karst region in Guizhou province. The major emphasis of this work is harvesting rainwater and its efficient use, control of soil erosion as also by various soil conservation measures in farmers’ fields. As a part of integrated watershed management, many other interventions are being evaluated in order to improve the income of the farmers along with soil and water management interventions

3D Photonic Crystals Assembled with Containerless-Solidified Amorphous BaTi2O5 Balls

Containerless solidification processing was introduced for the first time to fabricate 3D photonic crystal. Micrometer-sized amorphous BaTi2O5 spheres with perfect spherical shape and superior optical properties such as high refractive index (n=2.15) were produced via containerless solidification processing. 3D opal photonic crystal was assembled with these spheres by spaced-confined method using a box of precisely controlled size. Plane-wave method was implemented to calculate band structures and analyze influence of refractive index on band-gaps. The obtained results show that this 3D opal structure has incomplete band-gap, and band-gap narrows and moves toward lower frequency with the increase of refractive index along the [111] direction. The results demonstrate that the containerless solidification processing provides an approach to fabricate superior metastable spherical materials which can be used to form 3D opal photonic crystals

Nanocrystalline BaTi2O5 dielectric ceramic prepared by full crystallization from containerless solidified glass

We show that fully dense nanocrystalline titanate ceramic could be obtained by full crystallization from glass which was prepared by a novel contactless solidification process. Through annealing above glass transition temperature T-g for prescribed duration, BaTi2O5 ceramic with grain size of 20-130 nm was successfully fabricated. The dependence of the nanoceramic's dielectric constant and dissipation on frequency was investigated. The results show clearly that the dielectric constant of BaTi2O5 nanoceramic depends on average grain size in nanometer scale, and an optimal range of the grain size is found which exhibits greater dielectric constant than conventional microcrystalline ceramics. The as-fabricated ceramic also possesses lower dielectric dissipation, which can be mainly attributed to the presence of nanometer-sized grains

Lineage Tracing of Resident Tendon Progenitor Cells during Growth and Natural Healing

Unlike during embryogenesis, the identity of tissue resident progenitor cells that contribute to postnatal tendon growth and natural healing is poorly characterized. Therefore, we utilized 1) an inducible Cre driven by alpha smooth muscle actin (SMACreERT2), that identifies mesenchymal progenitors, 2) a constitutively active Cre driven by growth and differentiation factor 5 (GDF5Cre), a critical regulator of joint condensation, in combination with 3) an Ai9 Cre reporter to permanently label SMA9 and GDF5-9 populations and their progeny. In growing mice, SMA9 cells were found in peritendinous structures and scleraxis-positive (ScxGFP) cells within the tendon midsubstance and myotendinous junction. The progenitors within the tendon midsubstance were transiently labeled as they displayed a 4-fold expansion from day 2 to day 21 but reduced to baseline levels by day 70. SMA9 cells were not found within tendon entheses or ligaments in the knee, suggesting a different origin. In contrast to the SMA9 population, GDF5-9 cells extended from the bone through the enthesis and into a portion of the tendon midsubstance. GDF5-9 cells were also found throughout the length of the ligaments, indicating a significant variation in the progenitors that contribute to tendons and ligaments. Following tendon injury, SMA9 paratenon cells were the main contributors to the healing response. SMA9 cells extended over the defect space at 1 week and differentiated into ScxGFP cells at 2 weeks, which coincided with increased collagen signal in the paratenon bridge. Thus, SMA9-labeled cells represent a unique progenitor source that contributes to the tendon midsubstance, paratenon, and myotendinous junction during growth and natural healing, while GDF5 progenitors contribute to tendon enthesis and ligament development. Understanding the mechanisms that regulate the expansion and differentiation of these progenitors may prove crucial to improving future repair strategies

Grid workflow validation using ontology-based tacit knowledge: A case study for quantitative remote sensing applications

Workflow for remote sensing quantitative retrieval is the “bridge” between Grid services and Grid-enabled application of remote sensing quantitative retrieval. Workflow averts low-level implementation details of the Grid and hence enables users to focus on higher levels of application. The workflow for remote sensing quantitative retrieval plays an important role in remote sensing Grid and Cloud computing services, which can support the modelling, construction and implementation of large-scale complicated applications of remote sensing science. The validation of workflow is important in order to support the large-scale sophisticated scientific computation processes with enhanced performance and to minimize potential waste of time and resources. To research the semantic correctness of user-defined workflows, in this paper, we propose a workflow validation method based on tacit knowledge research in the remote sensing domain. We first discuss the remote sensing model and metadata. Through detailed analysis, we then discuss the method of extracting the domain tacit knowledge and expressing the knowledge with ontology. Additionally, we construct the domain ontology with Protégé. Through our experimental study, we verify the validity of this method in two ways, namely data source consistency error validation and parameters matching error validatio