Importance Of Such Measurements Research Articles

Volumetric reduction of brain metastases after stereotactic radiotherapy: Prognostic factors and effect on local control.

Few reports include volumetric measurements as endpoints after stereotactic radiotherapy (SRT) despite the importance of such measurements. This study aimed to (1) investigate the impact of the volumetric response (specifically, an over 65% and over 90% volume reduction in brain metastases) at 6months post-SRT on local control and (2) identify the predictive factors for a volumetric response of over 65% and over 90%. This study included 250 unresected brain metastases (>0.3cc) treated with SRT. Doses were stratified according to the biological effective dose (BED). The BED was calculated using four models: linear-quadratic (LQ): α/β=10; LQ: α/β=20; LQ cubic: α/β=12; and LQ linear: α/β=10. The median prescription dose was 30 Gy/3 fractions (BED20, 45). The median follow-up time after SRT was 18.6months (range, 6.4-81.8months). In the multivariate analysis, over 65% volume reduction and over 90% volume reduction were prognostic factors for local control (hazard ratio: 2.370, p=0.011 and hazard ratio: 3.161, p=0.014, respectively). A dose of 80% of the gross tumor volume (GTV) D80 > BED20 58 was a predictive factor for over 65% and over 90% volume reductions (odds ratio: 1.975, p=0.023; odds ratio: 3.204, p < 0.001, respectively). Robust volume reduction of brain metastases at 6months post-SRT can predict local control. GTV D80 in the LQ model: α/β=20 may be warranted for good volume reduction.

Are preoperative CT variables associated with the success or failure of subsequent ventral hernia repair: nested case-control study

ObjectivesSystematic review of CT measurements to predict the success or failure of subsequent ventral hernia repair has found limited data available in the indexed literature. To rectify this, we investigated multiple preoperative CT metrics to identify if any were associated with postoperative reherniation.MethodsFollowing ethical permission, we identified patients who had undergone ventral hernia repair and had preoperative CT scanning available. Two radiologists made multiple measurements of the hernia and abdominal musculature from these scans, including loss of domain. Patients were divided subsequently into two groups, defined by hernia recurrence at 1-year subsequent to surgery. Hypothesis testing investigated any differences between CT measurements from each group.ResultsOne hundred eighty-eight patients (95 male) were identified, 34 (18%) whose hernia had recurred by 1-year. Only three of 34 CT measurements were significantly different when patients whose hernia had recurred were compared to those who had not; these significant findings were assumed contingent on multiple testing. In particular, preoperative hernia volume (recurrence 155.3 cc [IQR 355.65] vs. no recurrence 78.2 [IQR 303.52], p = 0.26) nor loss of domain, whether calculated using the Tanaka (recurrence 0.02 [0.04] vs. no recurrence 0.009 [0.04], p = 0.33) or Sabbagh (recurrence 0.019 [0.05] vs. no recurrence 0.009 [0.04], p = 0.25) methods, differed between significantly between groups.ConclusionsPreoperative CT measurements of ventral hernia morphology, including loss of domain, appear unrelated to postoperative recurrence. It is likely that the importance of such measurements to predict recurrence is outweighed by other patient factors and surgical reconstruction technique.Key Points• Preoperative CT scanning is often performed for ventral hernia but systematic review revealed little data regarding whether CT variables predict postoperative reherniation.• We found that the large majority of CT measurements, including loss of domain, did not differ significantly between patients whose hernia did and did not recur.• It is likely that the importance of CT measurements to predict recurrence is outweighed by other patient factors and surgical reconstruction technique.

Estimation of fracture toughness of Zr 2.5% Nb pressure tube of Pressurised Heavy Water Reactor using cyclic ball indentation technique

In Pressurised Heavy Water Reactors (PHWRs) fuel bundles are located inside horizontal pressure tubes made up of Zr 2.5wt% Nb alloy. Pressure tubes undergo degradation during its service life due to high pressure, high temperature and radiation environment. Measurement of mechanical properties of degraded pressure tubes is important for assessing their fitness for further operation. Presently as per safety guidelines imposed by the regulatory body, a few pre-decided pressure tubes are removed from the reactor core at regular intervals during the planned reactor shut down to carry out post irradiation examination (PIE) in a laboratory which consumes lots of man-rem and imposes economic penalties. Hence a system is indeed felt necessary which can carry out experimental trials for measurement of mechanical properties of pressure tubes under in situ conditions. The only way to accomplish this important objective is to develop a system based on an in situ measurement technique. In the field of in situ estimation of properties of materials, cyclic ball indentation is an emerging technique. Presently, commercial systems are available for doing an indentation test either on the outside surface of a component at site or on a test piece in a laboratory. However, these systems cannot be used inside a pressure tube for carrying out ball indentation trials under in situ conditions. Considering the importance of such measurements, an In situ Property Measurement System (IProMS) based on cyclic ball indentation technique has been designed and developed indigenously. The remotely operable system is capable to carry out indentation trials on the inside surface of the pressure tube and estimates the important mechanical properties like yield strength, ultimate tensile strength, hardness etc. It is known that fracture toughness is one of the important life limiting parameters of the pressure tube. Effort has also been made to estimate the fracture toughness of the pressure tube using the data from ball indentation trials. Curved compact tension (CCT) specimens have been prepared from Zr 2.5wt% Nb pressure tube spool pieces having different mechanical properties. Fracture toughness of these specimens was measured by conventional test techniques which were later used as reference data for bench marking. This paper highlights the comparison between tensile properties measured from conventional tests and IProMS trials and relates the fracture toughness parameters measured from conventional tests with the IProMS estimated fracture properties. A methodology has been developed to relate the IProMS estimated properties like strength coefficient, indentation energy to fracture etc. with the fracture properties estimated through conventional tests.

Transport Properties of Multivalent Cations in Nafion-117 Membrane with Mixed Ionic Composition.

The transport characteristics of multivalent cations like Ba(2+) and Eu(3+) have been studied in bi-ionic form of the Nafion-117 membrane. The membranes have been prepared by loading different proportions of H(+)-Ba(2+)/Mg(2+)-Ba(2+)/Ba(2+)-Eu(3+)/H(+)-Eu(3+)/Na(+)-Eu(3+). The cationic compositions of the membranes have been determined from the measured ion exchange isotherms. Results show that the self-diffusion coefficient of Ba(2+) (D(Ba)) in H-Ba/Mg-Ba systems as well as the self-diffusion coefficient of Eu(3+) (D(Eu)) in H-Eu/Na-Eu systems are strongly dependent on the membrane ionic compositions and decreased continuously with increasing concentration of the highly hydrated ions (H(+)/Na(+)/Mg(2+)) in the membrane. Increase in the proportion of H(+)/Na(+)/Mg(2+) ions in the membrane increases the effective charge on the membrane matrix. This causes stronger electrostatic interaction of the less hydrated multivalent ions (Ba(2+)/Eu(3+)) with the membrane matrix charges, which ultimately results in their slower self-diffusion coefficients. The higher the valence, the stronger the electrostatic interaction is with the fixed ionic charges; hence, in general, D(Eu) is affected more as compared to D(Ba). On the basis of the free-volume theory for polymers, the effective interaction potential (Φ) of the Ba(2+) with the fixed ionic sites in the membrane has been calculated and found to be on the order of approximately millivolts. The higher the proportion of hydrated ion in the membrane, the higher the Φ is and the stronger the ion pair formation is with the fixed ionic sites in the membrane. However, in the Ba-Eu system, as the electrostatic interactions of the two ions with the membrane matrix are close, D(Ba) and D(Eu) are independent of the membrane ionic composition. The ionic composition dependence of D(Ba) in the H-Ba system is reflected in the transport rate of Ba(2+), showing the importance of such measurements in understanding the transport characteristics of the membrane.

Alternative Methods of Blackbody Thermodynamic Temperature Measurement Above Silver Point

Presently, absolute radiometry is the main method of thermodynamic temperature determination above the silver point. The importance of such measurements has increased, as a large international project is underway aimed at assigning thermodynamic temperatures to high-temperature fixed points (HTFPs). All participants are using filter radiometers calibrated against an absolute cryogenic radiometer which, therefore, will be the basis of the provided thermodynamic temperatures of the fixed points. However, such a unified approach may lead to systematic errors (if any) common to all participants. There are methods, providing an alternative to absolute radiometry, which allow the determination of blackbody thermodynamic temperatures using relative measurements. Alternative methods, even if they have lower accuracy than absolute radiometry, could disclose some possible unrecognized systematic errors, or, on the contrary, could confirm the results obtained using absolute radiometry and increase confidence of the thermodynamic temperature determination. One such method, known as the method of ratios (i.e., double wavelength technique), is based on measuring the ratios of fluxes emitted by a blackbody in separate spectral ranges at two temperatures. This approach has been developed at VNIIOFI, but its realization met serious technical difficulties. Modern sensors with improved sensitivity and stability, extremely reproducible HTFP blackbodies, and significant progress in computational methods and computer performance provide a new chance to realize this approach with sufficient accuracy. Another method is based on comparing the ratio of fluxes measured at two wavelengths for a high-temperature blackbody with that measured for synchrotron radiation. This article overviews possibilities of the alternative methods for determination of blackbody thermodynamic temperatures by means of relative radiometry to attract attention of the thermometry and radiometry communities to the importance of international cooperation for realization of these methods.

Stereo vision and strabismus.

Binocular stereopsis, or stereo vision, is the ability to derive information about how far away objects are, based solely on the relative positions of the object in the two eyes. It depends on both sensory and motor abilities. In this review, I briefly outline some of the neuronal mechanisms supporting stereo vision, and discuss how these are disrupted in strabismus. I explain, in some detail, current methods of assessing stereo vision and their pros and cons. Finally, I review the evidence supporting the clinical importance of such measurements.

Reexamining the empirical relation between plant growth and leaf photosynthesis.

Technological advances during the past several decades have greatly enhanced our ability to measure leaf photosynthesis virtually anywhere and under any condition. Associated with the resulting proliferation of gas-exchange data is a lingering uncertainty regarding the importance of such measurements when it comes to explaining intrinsic causes of plant growth variation. Accordingly, in this paper we rely on a compilation of data to address the following questions: from both statistical and mechanistic standpoints, how closely does plant growth correlate with measures of leaf photosynthesis? Moreover, in this context, does the importance of leaf photosynthesis as an explanatory variable differ among growth light environments? Across a wide array of species and environments, relative growth rate (RGR) was positively correlated with daily integrals of photosynthesis expressed per unit leaf area (Aarea), leaf mass (Amass), and plant mass (Aplant). The amount of RGR variation explained by these relationships increased from 36% for the former to 93% for the latter. Notably, there was close agreement between observed RGR and that estimated from Aplant after adjustment for theoretical costs of tissue construction. Overall, based on an analysis of growth response coefficients (GRCs), gross assimilation rate (GAR), a photosynthesis-based estimate of biomass gain per unit leaf area, explained about as much growth variation as did leaf mass ratio (LMR) and specific leaf area (SLA). Further analysis of GRCs indicated that the importance of GAR in explaining growth variation increased with increasing light intensity. Clearly, when considered in combination with other key determinants, appropriate measures of leaf gas exchange effectively capture the fundamental role of leaf photosynthesis in plant growth variation.

Numerical modelling of gamma radiation from galaxy clusters

We investigate the spatial and spectral properties of non-thermal emission from clusters of galaxies at γ-ray energies. We estimate the radiation flux between 10 keV and 10 TeV due to inverse-Compton (IC) emission, π 0 -decay and non-thermal bremsstrahlung (NTB) from cosmic ray (CR) ions and electrons accelerated at cosmic shocks as well as secondary e = generated in inelastic p-p collisions. We identify two main region of production of non-thermal radiation, namely the core (also bright in the thermal X-ray range) and the outskirts region where accretion shocks occur. We find that IC emission from shock-accelerated CR electrons dominate the emission at the outer regions of galaxy clusters, provided that at least a fraction of a per cent of the shock ram pressure is converted into CR electrons. A clear detection of this component and of its spatial distribution will allow us to probe the cosmic accretion shocks directly. In the cluster core, γ-ray emission above 100 MeV is dominated by the π 0 -decay mechanism. At lower energies, IC emission from secondary e ′ takes over. However, IC emission from shock-accelerated electrons projected on to the cluster core will not be negligible. We emphasize the importance of separating the aforementioned emission components for a correct interpretation of the experimental data and outline a strategy for that purpose. Failure to addresses this issue will produce unsound estimates of the intracluster magnetic field strength and CR ion content. According to our estimate future spaceborne and ground-based γ-ray facilities should be able to measure the whole non-thermal spectrum both in the cluster core and at its outskirts. The importance of such measurements in advancing our understanding of non-thermal processes in the intracluster medium is discussed.

Evidence for Orbital Decay of RX J1914.4+2456: Gravitational Radiation and the Nature of the X‐Ray Emission

RX J1914.4+2456 is a candidate double-degenerate binary (AM CVn) with a putative 569 s orbital period. If this identification is correct, then it has one of the shortest binary orbital periods known, and gravitational radiation should drive the orbital evolution and mass transfer if the binary is semi-detached. Here we report the results of a coherent timing study of the archival ROSAT and ASCA data for RX J1914.4+2456. We performed a phase coherent timing analysis using all five ROSAT observations spanning a 4.6 year period. We demonstrate that all the data can be phase connected, and we show evidence that the 1.756 mHz orbital frequency is increasing at a rate of 8 +- 3 e-18 Hz/s, consistent with the expected loss of angular momentum from the binary system via gravitational radiation. In addition to providing evidence for the emission of gravitational waves, our measurement of the orbital decay constrains models for the X-ray emission and the nature of the secondary. If stable mass accretion drives the X-ray flux, then orbital decay is inconsistent with a degenerate donor. A helium burning dwarf is compatible if indeed such systems can have periods as short as that of RX J1914.4+2456, an open theoretical question. Our measurement is consistent with the unipolar induction model of Wu et al. which does not require accretion to drive the X-ray flux. We discuss how future timing measurements of RX J1914.4+2456 (and systems like it) with for example, Chandra and XMM-Newton, can provide a unique probe of the interaction between mass loss and gravitational radiation. We also discuss the importance of such measurements in the context of gravitational wave detection from space, such as is expected in the future with the LISA mission.

Individual variation and lateral asymmetry of the rat primary somatosensory cortex

We have evaluated the interindividual variability and lateral symmetry of a major cortical area by comparing the primary somatosensory cortex (S1) of adult rats. Our choice of the rat was dictated by the accuracy with which one can measure S1 and its component representations in the rodent brain; the importance of such measurements lies in understanding the rules that govern the allocation of cortical space and, ultimately, the consequences of differential allocation for behavior. With respect to interindividual differences, the major somatic representations in S1 are surprisingly variable in size. The area of the whiskerpad representation, for example, ranged from 3.72 to 6.84 mm2 in a sample of 53 rats; other components of S1 showed comparable differences among animals. With respect to lateral symmetry, the average area of each major representation was similar for the right and left hemispheres; thus, we found no consistent bias in the size of S1 or its elements in the sample as a whole. Within individual animals, however, the sizes of the major somatic representations were often quite different in the two hemispheres. The magnitude of the lateral differences averaged 7.9 +/- 0.8% (mean +/- SEM) for the whisker pad representation, 11.6 +/- 1.3% for the upper lip, 15.4 +/- 1.6% for the furry buccal pad, 13.9 +/- 1.4% for the lower jaw, and 13.3 +/- 1.2% for the forepaw. These results show that the amount of cortical space allocated to corresponding functions in individual rats--or in the two hemispheres of a particular rat--are often different. Such variations are likely to be reflected in somatosensory performance.

Electrical measurements as performance indicators of electromigration

AbstractMeasurements were made of various electrical parameters on metal interconnects at intervals during electromigration life tests. The results show a close correlation between the progression of electro‐migration and increases of the resistance values, harmonic content and excess noise. Also, the statistical trend of the variations of these parameters with normalized lifetime for a number of failed samples is very consistent with the trend during a continuously monitoring experiment, where the electrical properties of tracks were monitored continuously while being electrically and thermally stressed. There are implications in the potential importance of such measurements for the non‐destructive tests of electromigration.

The airborne aerosol inlet workshop: Meeting report

The measurement of atmospheric aerosol properties (i.e. concentration, size, and composition) from an airborne platform is faced by formidable obstacles. The largest problem is one of getting an undisturbed sample into the aerosol sensor sampling volume or onto a filter for subsequent analysis. The importance of such measurements led to the planning of a workshop to address the difficulties and to assess the present state of airborne aerosol sampling technology. The workshop focused on discussions of observational, experimental and theoretical studies of aerosol inlets. The product of this workshop was a summary of the limitations of sampling inlets currently used for airborne applications and a set of recommendations to overcome these limitations and improve the general quality of such measurements.

Direct measurement of the contact angle on plates and on thin fibres: some theoretical aspects

The experimental problem of making accurate measurement of the contact angle by direct measurement in systems where the substrate is in the form of either a plane or a thin cylinder is discussed theoretically. The importance of such measurements of the liquid meniscus curvature close to the solid surface is discussed in a quantitative way. It is shown that, by arranging for one of the contacting phases to be in either the droplet or the bulk form, it is possible, in principle, to make direct measurements in all the systems considered. With cylinders, the facility of the experiment increases with an increase in the cylinder diameter.

Urine chromium as an estimator of air exposure to stainless steel welding fumes.

Welding stainless steel with covered electrodes, also called manual metal arc welding, generates hexavalent airborne chromium. Chromium concentrations in air and post-shift urine samples, collected the same arbitrarily chosen working day, showed a linear relationship. Since post-shift urine samples reflect chromium concentrations of both current and previous stainless steel welding fume exposure, individual urine measurements are suggested as approximate although not exact estimators of current exposure. This study evaluates the practical importance of such measurements by means of confidence limits and tests of validity.

Termolecular and saturated termolecular kinetics for Li+ and F−

The termolecular association of Li+ with nineteen molecules was observed in helium at 0.3–1.0 torr. The molecules included N2, CO2, SO2, NH3, substituted methanes, and substituted ethylenes. The rates ranged from 8(−31) to 5(−27) cm6 molecule−2 sec−1. Six molecules were observed to have a transition from termolecular to saturated termolecular kinetics in the 0.3 to 1.0 torr pressure range and C4F8, C2Cl2F4, and C2F6 were saturated termolecular at 0.2 torr in both helium and argon buffer and their rate constants were independent of buffer. Some qualitative comparisons are made on the Li+ association data. The F− associations with NH3, CO2, and SO2 were measured and the large rate for CO2 and SO2 indicates covalent bonding in these compounds. The over-all importance of such measurements as a ``tunable'' probe of kinetics is emphasized.

ELECTRODIAGNOSIS OF NEUROMUSCULAR DISEASE

THE past decade has seen a number of the techniques of clinical neurophysiology come into common use in the diagnosis of neuromuscular disease. One of these is the measurement of conduction velocity of motor nerves. Conduction velocity of nerves was only of academic interest until 1948 when a simple method for making reliable measurements in man was described and proved useful as a test of nerve function. It is now a frequent subject of clinical investigation and in many laboratories measurement of conduction velocity has become a routine diagnostic procedure. A review and extension of this work by Dunn and his associates, published in this issue of Pediatrics, emphasizes the importance of such measurements to pediatrics wherein objective evidence of functional impairment of nerves is of particular importance because the clinical examination may be so unsatisfactory. Conduction velocity of peripheral nerves, measurable quickly and simply, should be standard practice in the study of neuromuscular disorders in infants and children.

The role of hydrogen bonds in condensed monolayers

From the behaviour of monolayers of compounds containing the —CO.NH— linkage it is concluded that intermolecular hydrogen bonding can play a major role in determining the properties of condensed monolayers. Such effects, which are well marked in the ureas, amides, acetanilides, unsubstituted and α -amino acids, tend to bring about condensation and solidification, and a marked increase in the half-expansion temperature. A detailed examination of the acetamides has been made in both the expanded and condensed regions by combined force area and surface potential methods. Comparison of the condensed films with those of the analogous acetates, where no such intermolecular hydrogen bonding is possible, shows several striking differences. With the acetamides and ureas the hydrogen bonding has been shown to be quite sensitive to the pH of the substrate, very acid substrates leading to complete liquefaction. The hydrogen bond distances can be calculated and the values so obtained are found to agree quite well with those in the crystal for the same or similar head groups. The free energy difference between the —CO.NH— group when forming hydrogen bonds to water (as in the expanded films), and when cross-linked (as in the low temperature form), is calculated for the acetamides to be about 840 cal./g.mol. Values of the same order can be calculated for the other systems discussed. The importance of such measurements in determining the part played by the hydrogen bond in the protein molecule is pointed out.

The measurement of contact potential difference

A number of measurements of the contact potential difference between pairs of dissimilar metals has been made during the last few years. The interest and importance of such measurements arise chiefly in connexion with the theoretical relation which exists between the contact potential difference and the work functions of the surfaces considered. This relation, due to Richardson, may be written V c = Φ 1 - Φ 2 + P, (1) where P is a correction for the Peltier effect which, in practice, is negligibly small. If Φ 2 &gt; Φ 1 , the sign of V c will be such that surface 1 is positive with respect to surface 2. It has been pointed out by Compton and Langmuir that equation (1) cannot hold for surfaces which are not homogeneous, since contact potential measurements would yield average values for the whole surfaces, while the magnitude of the work function, measured either by the photoelectric or the thermionic method, would be determined principally by the most electropositive portions of the surface. Farnsworth and Rose have shown that these considerations may apply even for clean metal surfaces, since recent measurements by Rose§ indicate that comparatively large contact potential differences may exist between different faces of crystals of the same metal, so that polycrystalline surfaces cannot necessarily be considered as homogeneous.

β-ray spectra of thorium disintegration products

In problems relating to atomic structure the study of β-ray spectra is becoming of increasing importance. It is therefore desirable that an accurate analysis should be made for as many substances as possible which emit β rays. This has been done in great detail by Ellis, and by Ellis and Skinner, for radium B and radium C, and they have shown that the γ rays which eject the electrons from the atoms can be arranged in a system of levels. Recently the author made an analysis of the β-ray spectrum of mesothorium 2, and found that most of the γ rays from this substance could also be accounted for by a system of levels. The β-ray spectrum of thorium B and of thorium C + D had previously been measured by Ellis and also by Meitner. Since that time the technique of the measurement of β-ray spectra has been greatly improved. Therefore, considering the importance of such measurements in modern atomic theories, it was most essential that an accurate analysis of the spectrum of these substances should be made. Moreover, the previous measurements for these spectra were based on the then accepted values for lines of the radium B spectrum, which recent work has .shown to need a small correction.

Summary of the results of recent investigations in atmospheric electricity

IV. VARIATION WITH ALTITUDE OF FALL OF POTENTIAL.That the Earth possesses a negative charge is shown by the generally positive fall of potential. Whether there exist also in the air electric charges, and, if so, whether they be positive or negative, can not be decided by observations made at the surface of the Earth; for this purpose observations in the upper regions alone suffice. If we premise a uniform distribution in the air of the charges in question along horizontal layers, then, in the absence of a charge of the air of its own, the fall of potential should remain constant for the same altitude; in the case of a positive charging of the air the fall of potential must decrease, and for a negative charge, the same should increase. I, therefore, some time ago pointed out the importance of such measurements, and have shown how it would be possible to carry them out in a balloon without conduction with the Earth. Parenthetically it may be remarked, that similar observations on high mountains, on account of the disturbances in the equipotential planes, can not replace, for this purpose, the balloon observations.