Changes In Mass Density Research Articles

Vertical patterns in specific volume increment along stems of dominant jack pine (Pinus banksiana) and black spruce (Picea mariana) after thinning

Jack pine ( Pinus banksiana Lamb.) and black spruce ( Picea mariana (Mill.) B.S.P.) total stem volume increment and vertical growth distribution after thinning were quantified and related to foliage biomass, foliage density, and growth efficiency (GE) (stem to foliage biomass ratio). Significant positive stem volume increments were observed following thinning for jack pine (3 years after) and black spruce (4 years after). Both species reacted differently in terms of the distribution in specific volume increments (SVI) (annual stem volume increment to cambial surface ratio): (i) for jack pine, an increase in SVI was first observed at the base of the tree, with the increase moving upwards, showing that the taper was likely to increase following thinning and (ii) for black spruce, the vertical distribution of SVI was constant, leading to no modifications in stem taper. For jack pine, total stem volume growth was related to an increase in GE and a greater foliage biomass at midcrown, with foliage density staying constant. For black spruce, however, no changes in GE, foliage biomass, and foliage mass density were observed.

Dynamic voids surrounded by shocked conventional polytropic gas envelopes

With proper physical mechanisms of energy and momentum input from around the centre of a self-gravitating polytropic gas sphere, a central spherical "void" or "cavity" or "bubble" of very much less mass contents may emerge and then dynamically expand into a variety of surrounding more massive gas envelopes with or without shocks. We explore self-similar evolution of a self-gravitating polytropic hydrodynamic flow of spherical symmetry with such an expanding "void" embedded around the center. The void boundary supporting a massive envelope represents a pressure-balanced contact discontinuity where drastic changes in mass density and temperature occur. We obtain numerical void solutions that can cross the sonic critical surface either smoothly or by shocks. Using the conventional polytropic equation of state, we construct global void solutions with shocks travelling into various envelopes including static polytropic sphere, outflow, inflow, breeze and contraction types. In the context of supernovae, we discuss the possible scenario of separating a central collapsing compact object from an outgoing gas envelope with a powerful void in dynamic expansion. Initially, a central bubble is carved out by an extremely powerful neutrinosphere. After the escape of neutrinos during the decoupling, the strong electromagnetic radiation field and/or electron-positron pair plasma continue to drive the cavity expansion. In a self-similar dynamic evolution, the pressure across the contact discontinuity decreases with time to a negligible level for a sufficiently long lapse and eventually, the gas envelope continues to expand by inertia. We describe model cases of polytropic index $\gamma=4/3-\epsilon$ with $\epsilon>0$ and discuss pertinent requirements to justify our proposed scenario.

Matched‐cohort study of body composition, physical function, and quality of life in men with idiopathic vertebral fracture

To determine the effect of 6 years of routine management on body composition, physical functioning, and quality of life, and their interrelationships, in men with idiopathic vertebral fracture. Twenty men with idiopathic vertebral fracture (patients: mean ± SD age 58 ± 6 years) were age and height matched to 28 healthy controls with no known disease. The primary outcome was skeletal muscle mass (appendicular lean mass by dual x-ray absorptiometry) assessed at 2 visits (0 and 6 years). Physical functioning and quality of life domains were assessed by the Senior Fitness Test and Short Form 36 (SF-36) questionnaire at visit 2 only. Data were analyzed by repeated-measures analysis of variance, independent t-tests, and correlation. At visit 1, appendicular lean mass was 9% lower in patients than controls. Although patients better maintained appendicular lean mass between visits (interaction P = 0.016), at visit 2 appendicular lean mass remained 5% lower in patients than controls. Furthermore, patients' appendicular lean mass change was correlated with femoral neck bone density change (r = 0.507, P = 0.023). Physical function tests were 13-27% lower in patients compared with controls (P = 0.056 to 0.003), as were SF-36 quality of life physical domains (13-26% lower; P = 0.028 to <0.001). Despite an association between changes in muscle mass and bone density, routine management of men with idiopathic vertebral fracture does not address muscle loss. Combined with the observation of reduced physical functioning and quality of life, this study identifies novel targets for intervention in men with idiopathic vertebral fracture.

Bone mineral metabolism in patients with neurofibromatosis type 1 (von Recklingausen disease)

The neurofibromatosis type 1 (NF1) is characterized by specific cutaneous features (neurofibromas, "café-au-lait" spots of the skin) and alterations of several tissue (nervous, vascular) and bone deformities, such as scoliosis, congenital pseudoarthrosis and bone dysplasia of tibia. Moreover, several studies have shown systemic involvement of bone tissue in NF1 patients, leading to reduced bone mass. The aim of our study was to evaluate some bone mineral metabolism parameters before and after calcium and vitamin D supplementation in NF1 patients. We evaluated in 70 NF1 consecutive patients the mineral metabolism and bone mineral density compared with 40 normal subjects. We showed bone alterations in 35% of patients and the increase of bone formation markers, such as bone isoenzyme of alkaline phosphatase (41.2±15.5 vs. 25.6±8.7UI; P<0.05, respectively) and osteocalcin (18.1±5.6 vs. 7.6±1.9ng/ml; P<0.05) and reduction of circulating levels of (25OH)-vitamin D (21.8±12.3ng/ml) with an high percentage of hypovitaminosys D (>60%). Moreover, we revealed a significant reduction of bone mass density at spine (L1-L4) (0.935±0.13 vs. 1.110±0.17g/cm(2); P<0.001) and femoral neck side (0.765±0.09 vs. 0.839±0.12g/cm(2); P<0.02), with high prevalence of osteopenia (44%) and osteoporosis (18%). After 12months of calcium (1,200mg/die) and cholecalciferol (800UI/die) supplementation, we found a significant increase of (25) OH-vitamin D level (21.8±12.3 vs. 35±13ng/ml; P<0.01), without changes in bone mass density. In conclusion, NF1 patients may present a mineral bone involvement, with vitamin D deficiency; calcium and vitamin D supplementation is necessary to restore these bone mineral metabolic alterations.

Ultrasonic Setup for Testing Hydrogels: Preliminary Experiments on Collagen Gels

The assessment of mechanical properties of highly hydrated natural materials remains a challenge because, in general, their mechanical evaluation implies invasive and finally destructive methods. Acoustic-based tests may represent the appropriate tools to investigate the mechanical properties of such materials, particularly collagen gels, whose acoustic properties are poorly understood. The objective of this work is to develop two experimental setups for the assessment of acoustic properties of such a hydrogels. In the first one, a typical pulse echo reflectometer was implemented. The acoustic parameters were measured at controlled temperature in an especially designed chamber. In the second one, the previous configuration was combined with a setup for compressive tests, allowing to interrogate simultaneously both the acoustic and mechanical properties of the sample under test. The frequency of the acoustic transducer was 10MHz. The acoustic and mechanical properties of collagen gels prepared according to different experimental conditions (pH and collagen concentration) were evaluated. The first set of experiment was useful to accomplish estimation of the speed of sound, attenuation and acoustic impedance. The second one allowed us to monitor the speed of sound during the evolution of the compression test. This approach could be a potential tool to study the changes in hydrogels mass density and bulk compressibility.

Long-term regional sea level changes due to variations in water mass density during the period 1981-2007

[1] Using a gridded ocean temperature and salinity field based on observations, the regional distribution of sea level changes during the last few decades was investigated. We calculated the baroclinic sea level change and decomposed it into vertical modes of pressure perturbation for internal waves, considering the vertical structure of the baroclinic pressure change. The first mode is associated with vertical displacement of the main pycnocline, which is generally a dynamical response to wind forcing, as demonstrated by previous studies using shallow water models. Regional sea level variations associated with this mode have large magnitudes, especially in the tropics, where, as shown by previous studies, interannual variability is relatively large compared to sea level changes. Other factors affecting sea level include changes in water mass density and horizontal movement of water masses. These are characterized as second and higher modes, and their combined effect on the amplitude of regional sea level changes is comparable with that of the first mode, especially in subtropical gyre regions. In the North Pacific, the combined second and higher order modes give rise to significant positive sea level trends. These long-term sea level trends are induced by steric contributions resulting from warming and freshening of the subtropical mode waters. This result suggests that changes in water mass properties such as temperature and salinity are also important for replicating local sea level change, especially in the subtropical gyre region.

Microstructure and stiffness of Scots pine (Pinus sylvestris L) sapwood degraded by Gloeophyllum trabeum and Trametes versicolor – Part I: Changes in chemical composition, density and equilibrium moisture content

Abstract Fungal degradation alters the microstructure of wood and its physical and chemical properties are also changed. While these changes are well investigated as a function of mass loss, mass density loss and changes in equilibrium moisture content are not well elucidated. The physical and chemical alterations are crucial when linking microstructural characteristics with macroscopic mechanical properties. In the present article, a consistent set of physical, chemical and mechanical characteristics is presented, which were measured on the same sample before and after fungal degradation. In the first part of this two-part contribution, elucidating microstructure/stiffness-relationships of degraded wood, changes in physical and chemical data are presented, which were collected from specimens of Scots pine (Pinus sylvestris) sapwood degraded by Gloeophyllum trabeum (brown rot) and Trametes versicolor (white rot) for up to 28 weeks degradation time. A comparison of mass loss with corresponding mass density loss demonstrated that mass loss entails two effects: firstly, a decrease in sample size (more pronounced for G. trabeum), and secondly, a decrease of mass density within the sample (more pronounced for T. versicolor). These two concurrent effects are interrelated with sample size and shape. Hemicelluloses and cellulose are degraded by G. trabeum, while T. versicolor was additionally able to degrade lignin. In particular because of the breakdown of hemicelluloses and paracrystalline parts of cellulose, the equilibrium moisture content of degraded samples is lower than that in the initial state.

Structural and photoelectrochemical properties of Ti1−xWxO2 thin films deposited by magnetron sputtering

W-doped titanium dioxide is a promising candidate material for applications ranging from UV–VIS light photocatalytic reactions to catalyst support in proton-exchange membrane fuel cells, depending on the doping content. The present study reports on the possibility to synthesize substitutional Ti1−xWxO2 thin films with 0≤x≤1 by magnetron co-sputtering from Ti and W metallic targets. Two routes were investigated starting from 1) crystalline titanium tungsten alloys deposited in non-reactive (pure Ar) mode, and 2) amorphous titanium tungsten oxides deposited in reactive (Ar+O2 atmosphere) mode. The structure and phase stability after air annealing at 550°C has been investigated by X-ray Diffraction (XRD). X-ray Reflectivity (XRR) was used to determine the change in film mass density upon annealing. Films of the non-reactive mode series could not be successfully fully oxidized into Ti1−xWxO2 form. For the reactive mode film series, ternary Ti1−xWxO2 oxides were obtained after air annealing and the crystal structure was changed from anatase to rutile with increasing W content in the range 0–33at.%. Films with higher W content (0.33<x≤1) eventually crystallized in the WO3 triclinic structure. Photo-electrodes were elaborated from the deposited thin films on FTO coated glass, and they all showed photo-response when tested in acid solution, under UV–VIS illumination. Among the doped materials, the Ti0.92W0.08O2 thin film showed the highest photo-current.

Thermospheric mass density variations during geomagnetic storms and a prediction model based on the merging electric field

Abstract. With the help of four years (2002–2005) of CHAMP accelerometer data we have investigated the dependence of low and mid latitude thermospheric density on the merging electric field, Em, during major magnetic storms. Altogether 30 intensive storm events (Dstmin&lt;−100 nT) are chosen for a statistical study. In order to achieve a good correlation Em is preconditioned. Contrary to general opinion, Em has to be applied without saturation effect in order to obtain good results for magnetic storms of all activity levels. The memory effect of the thermosphere is accounted for by a weighted integration of Em over the past 3 h. In addition, a lag time of the mass density response to solar wind input of 0 to 4.5 h depending on latitude and local time is considered. A linear model using the preconditioned Em as main controlling parameter for predicting mass density changes during magnetic storms is developed: ρ=0.5 Em + ρamb, where ρamb is based on the mean density during the quiet day before the storm. We show that this simple relation predicts all storm-induced mass density variations at CHAMP altitude fairly well especially if orbital averages are considered.

Effects of Intramuscular Testosterone Undecanoate on Body Composition and Bone Mineral Density in Female-to-Male Transsexuals

The most common treatment regimen in female-to-male transsexuals is administration of short-acting testosterone esters intramuscularly every 2 weeks. The aim of this study was to evaluate the effect of long-acting intramuscular testosterone undecanoate on body composition and bone mineral density during cross-sex hormone therapy in female-to-male transsexuals. Forty-five female-to-male transsexuals (FtMs) were treated with injections of testosterone undecanoate 1,000 mg intramuscularly every 12 weeks over 24 months. Body composition, bone mineral density, hormone parameters, and lipids were compared after 12 months and after 24 months with baseline values. Sonographic findings in the ovaries and endometrium, clinical and adverse effects during the study period were recorded. There was a significant increase in lean mass in the FtMs during the study period in comparison with baseline values, whereas no change in BMI, fat mass, and bone mineral density was observed. There was a significant decline in gonadotropins, estradiol, dehydroepiandrosterone sulphate, sex hormone-binding globulin, and high-density lipoprotein, while testosterone and triglyceride levels increased significantly after 12 and 24 months. Ovaries remained unchanged and no noticeable endometrial pathology was observed. No mortality or morbidity was observed during the study period. We observed a cessation of menstrual bleeding, an increase in clitoral growth, libido, body and beard hair growth, deepened voices and decline in breast size. There was a significant increase in hemoglobin, hematocrit, glutamic-pyruvic transaminase, gamma-glutamyl transferase, and an increase in systolic blood pressure during the study period. There was an increase in lean mass during the study period in FtMs treated with testosterone undecanoate. Transsexual patients should be monitored for adverse effects on lipid profiles, blood pressure, and erythrocytosis during intramuscular testosterone undecanoate therapy.

A Geometric Theory of Growth Mechanics

In this paper we formulate a geometric theory of the mechanics of growing solids. Bulk growth is modeled by a material manifold with an evolving metric. Time dependence of metric represents the evolution of the stress-free (natural) configuration of the body in response to changes in mass density and "shape". We show that time dependency of material metric will affect the energy balance and the entropy production inequality; both the energy balance and the entropy production inequality have to be modified. We then obtain the governing equations covariantly by postulating invariance of energy balance under time-dependent spatial diffeomorphisms. We use the principle of maximum entropy production in deriving an evolution equation for the material metric. In the case of isotropic growth, we find those growth distributions that do not result in residual stresses. We then look at Lagrangian field theory of growing elastic solids. We will use the Lagrange-d'Alembert's principle with Rayleigh's dissipation functions to derive all the governing equations. We make an explicit connection between our geometric theory and the conventional multiplicative decomposition of deformation gradient $\mathbf{F}=\mathbf{F}_e\mathbf{F}_g$ into growth and elastic parts. We linearize the nonlinear theory and derive a linearized theory of growth mechanics. Finally, we obtain the stress-free growth distributions in the linearized theory.

High sensitive piezoelectric quartz crystal liquid density sensor

We report for the first time a cleavage phenomenon in the resonant peak of a piezoelectric quartz crystal (PQC) in liquid phase. In the presence of a strong longitudinal wave effect, an additional resonant peak appears in the conductance–frequency curve. With gradually increasing liquid density, the additional peak moves from low to high frequency region then disappears. The frequency of the additional resonant peak is sensitive to the change in liquid density. The frequency shift of the additional peak is linear with the liquid density in a given range. For a 5 MHz PQC with a reflection distance of 16 mm for longitudinal wave, the sensitivity to liquid density is 2.61 × 10 6 Hz g −1 cm 3. The overlap between the primary resonant peak and the additional resonant peak causes a decrease in the intensity of the former and an increase in the intensity of the latter. In a combined impedance analysis method, the changes in surface mass loading, density and viscosity of the liquid were monitored simultaneously by a PQC sensor.

Micro-Scratching of UHMW Polyethylene Surfaces

Ultra-high molecular weight polyethylene has been micro-scratched with 90° cube corner tips. The scratch mode was flat-on, uni-directional and single pass. The micro-scratches and cross-sectional scratch profiles were characterised with atomic force microscopy. No detached debris is produced. Cross-sectional scratch profiles have been analysed using Zum Gahr’s formalism giving an fab ratio slightly above zero. This is consistent with expectation for ductile polymers where none or little detached debris is produced. However, the observation contrasts with that for other polymers, such as PMMA, PEP and PC, for which inconclusive results suggest an excess pile-up implying an inconceivable change of mass density or material gain.

Body Composition Alterations, Energy Expenditure and Fat Oxidation in Elderly Males Suffering from Prostate Cancer, Pre and Post Orchiectomy

INTRODUCTIONTestosterone is needed for normal male development, muscle strength, bone mineralization, hematopoietic function, and sexual and reproductive functions. The main purpose of androgen deprivation therapy in prostate cancer is to reduce tumor progression, but therapy is often accompanied by significant adverse effects.OBJECTIVEThis study aimed to determine the effects of androgen deprivation therapy on body composition and resting metabolic rate in patients with prostate cancer.PATIENTS AND METHODSA prospective study was performed to evaluate the body composition of 16 elderly males (aged 63–96; median age 71) with prostate cancer scheduled for orchiectomy, one year before and after surgery. Body composition was measured by DEXA, and energy expenditure, fat and carbohydrate oxidation were measured by indirect calorimetry.RESULTSBody weight (p=0.01), lean mass (p=0.004), and lipid oxidation (p=0.001) decreased significantly. Carbohydrate oxidation (p=0.02), FSH (p=0.0001) and LH (p=0.0001) levels increased significantly. Changes in fat mass (p=0.06) and bone mineral density (p=0.48) were not significant.CONCLUSIONSAfter 12 months of androgen deprivation therapy, elderly men with metastatic prostate cancer exhibit a decline in lean body mass and lipid oxidation, together with increased carbohydrate oxidation.

Thermal structure of a gas‐permeable lava dome and timescale separation in its response to perturbation

The thermal boundary layer at the surface of a volcanic lava dome is investigated through a continuum model of the thermodynamic advection‐diffusion processes resulting from magmatic gas flow through the dome matrix. The magmatic gas mass flux, porosity, and permeability of the rock are identified as key parameters. New, theoretical, nonlinear steady state thermal profiles are reported, which give a realistic surface temperature of 210°C for a region of lava dome surface through which a gas flux of 3.5 × 10−3 kg s−1 m−2 passes. This contrasts favorably with earlier purely diffusive thermal models, which cool too quickly. Results are presented for time‐dependent perturbations of the steady states as a response to changes in surface pressure, a sudden rockfall from the lava dome surface, and a change in the magmatic gas mass flux at depth. Together with a generalized analysis using the method of multiple scales, this identifies two characteristic timescales associated with the thermal evolution of a dome carapace: a short timescale of several minutes, over which the magmatic gas mass flux, density, and pressure change to a new quasi‐steady state and a longer timescale of several days, over which the thermal profile changes to a new equilibrium distribution. Over the longer timescale, the dynamic properties of the dome continue to evolve, but only in slavish response to the ongoing temperature evolution. In light of this timescale separation, the use of surface temperature measurements to infer changes in the magmatic gas flux for use in volcanic hazard prediction is discussed.

Crystallization Characteristics of Ge-Sb Phase Change Materials

AbstractThe crystallization behavior of Ge-Sb phase change materials with variable Ge:Sb ratio X between 0.079 and 4.3 was studied using time-resolved x-ray diffraction, differential scanning calorimetry, x-ray reflectivity, optical reflectivity and resistivity vs. temperature measurements. It was found that the crystallization temperature increases with Ge content from about 130 °C for X = 0.079 to about 450 °C for X = 4.3. For low X, Sb x-ray diffraction peaks occurred during a heating ramp at lower temperature than Ge diffraction peaks. For X = 1.44 and higher, Sb and Ge peaks occurred at the same temperature. Mass density change upon crystallization and optical and electrical contrast between the phases show a maximum for the eutectic alloy with X = 0.17. The large change in materials properties with composition allows tailoring of the crystallization properties for specific application requirements.

Effect of Fluorescently Labeling Protein Probes on Kinetics of Protein−Ligand Reactions

We studied the effect of fluorescently labeling proteins on protein-ligand reactions. Unlabeled ligands (streptavidin-binding peptides and rabbit immunoglobulin G (IgG) as antigen targets) are immobilized on epoxy-functionalized glass slides. Unlabeled and Cy3-labeled protein probes from the same batch (streptavidin and goat antibodies) subsequently react with the surface-immobilized targets. By monitoring in situ the surface mass density change using an oblique-incidence reflectivity difference scanning microscope (a label-free detector), we measured k(on) and k(off) for streptavidin-peptide reactions and antibody-antigen reaction. We found that (1) equilibrium dissociation constants, defined as K(D) = k(off)/k(on), for streptavidin-peptide reactions increases by a factor of 3-4 when the solution-phase streptavidin is labeled with Cy3 dye and (2) K(D) for reactions of solution-phase goat anti-rabbit antibodies with rabbit IgG targets also change significantly when the goat antibodies are labeled with Cy3 dye.

An empirical relation to correct storm-time thermospheric mass density modeled by NRLMSISE-00 with CHAMP satellite air drag data

With the help of STAR (Spatial Triaxial Accelerometer for Research) accelerometer measurements on board CHAMP (Challenging Minisatellite Payload), the global distributions of total mass density changes at about 400 km height during major magnetic storms are studied, aiming to improve the capability of current thermospheric model for predicting the storm-time mass density distribution. The density calculated by the NRLMSISE-00 model without using the geomagnetic active index as input is taken as a reference on top of which the storm-time changes are added. In total 19 storm events during 2001–2004 are used to perform a comprehensive statistical analysis. A relative calibration of drag coefficient along with accelerometer calibration parameters is made by fitting the CHAMP observed initial mass densities in with the NRLMSISE-00 model on quiet days before each storm. The dependences of the storm-time changes in mass density on both the total global Joule heating power, ∑ Q j and the high-resolution ring current index, Sym-H, are investigated. The lag times of mass density changes with respect to the Joule heating and Sym-H variation are obtained as a function of latitude and sunlight. By using a multiple linear regression analysis with proper time shift, an empirical relation connecting storm-time changes in mass density for 400 km height with the two parameters, ∑ Q j and Sym-H, has been worked out for different latitude and sunlight conditions (day-side or night-side). Adding a correction calculated from the empirical relation to the NRLMSISE-00 model reference leads to a better prediction of storm-time thermospheric mass density distribution.

Protein reactions with surface-bound molecular targets detected by oblique-incidence reflectivity difference microscopes

We applied oblique-incidence reflectivity difference microscopes (a form of polarization-modulated nulling ellipsometry) to detection of biomolecular microarrays without external labeling in a study of protein reactions with surface-immobilized targets. We show that the optical reflectivity difference signals can be quantitatively related to changes in surface mass density of molecular layers as a result of the reactions. Our experimental results demonstrate the feasibility of using oblique-incidence reflectivity difference microscopes for high-throughput proteomics research such as screening unlabeled protein probes against libraries of surface-immobilized small molecules.

Plasmon-waveguide resonance (PWR) spectroscopy for directly viewing rates of GPCR/G-protein interactions and quantifying affinities

Plasmon-waveguide resonance (PWR) spectroscopy is an optical technique that has been developed in our laboratories and applied to the study of membrane-associated proteins, especially GPCRs. It has high sensitivity and requires no labeling of materials, and it can monitor changes in proteolipid mass density and conformation in real time using plasmon excitation by light polarized both perpendicular and parallel to the resonator surface. Direct measurements will be described of the association of ligands and G-proteins to GPCRs incorporated into a self-assembled lipid bilayer deposited on the silica surface of a PWR resonator. These studies have provided new insights into the functioning of this important class of signaling proteins.