scholarly journals THE EFFECT OF RADIOACTIVE RADIATIONS AND X-RAYS ON ENZYMES

1926 ◽  
Vol 9 (3) ◽  
pp. 309-313 ◽  
Author(s):  
Raymond G. Hussey ◽  
William R. Thompson
Keyword(s):  
Gamma Radiation ◽  
Fluid Layer ◽  
Beta Radiation ◽  
Sufficient Condition ◽  
X Rays ◽  
Dilute Solution ◽  
The Mean ◽  
Necessary And Sufficient ◽  
Reaction Speed

Evidence is presented which indicates: (1) that the effect of gamma radiation is negligible with respect to that of beta radiation upon pepsin in dilute solution under the conditions employed in the experiments made; (2) approximately the thickness of fluid layer which may be regarded as necessary and sufficient to practically completely absorb the available beta radiation; (3) that the mean reaction speed coefficient in radiochemical inactivation of pepsin varies inversely with the volume of solution irradiated if the thickness of the fluid layer satisfies the sufficient condition stated in (2), and beyond this as far as has been studied.

A note on the subcritical generalized age-dependent branching process

1976 ◽  
Vol 13 (4) ◽  
pp. 798-803 ◽  
Author(s):  
R. A. Doney
Keyword(s):  
Branching Process ◽  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
Malthusian Parameter ◽  
Age Dependent ◽  
The Mean ◽  
Mean Function ◽  
Necessary And Sufficient

For a subcritical Bellman-Harris process for which the Malthusian parameter α exists and the mean function M(t)∼ aeat as t → ∞, a necessary and sufficient condition for e–at (1 –F(s, t)) to have a non-zero limit is known. The corresponding condition is given for the generalized branching process.

THE COMPATIBLE BOND-STOCK MARKET WITH JUMPS

2011 ◽  
Vol 14 (05) ◽  
pp. 723-755 ◽  
Author(s):  
DEWEN XIONG ◽  
MICHAEL KOHLMANN
Keyword(s):  
Stock Market ◽  
Marked Point ◽  
Quadratic Functions ◽  
Marked Point Process ◽  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
No Arbitrage ◽  
The Mean ◽  
Necessary And Sufficient ◽  
Mean Variance

We construct a bond-stock market composed of d stocks and many bonds with jumps driven by general marked point process as well as by an ℝn-valued Wiener process. By composing these tools we introduce the concept of a compatible bond-stock market and give a necessary and sufficient condition for this property. We study no-arbitrage properties of the composed market where a compatible bond-stock market is arbitrage-free both for the bonds market and for the stocks market. We then turn to an incomplete compatible bond-stock market and give a necessary and sufficient condition for a compatible bond-stock market to be incomplete. In this market we consider the mean-variance hedging in the special situation where both B(u, T) and eG(u, y, T)-1 are quadratic functions of T - u. So, we need to extend the notion of a variance-optimal martingale (VOM) as in Xiong and Kohlmann (2009) to the more general market. By introducing two virtual stocks [Formula: see text], we prove that the VOM for the bond-stock market is the same as the VOM for the new stock market [Formula: see text]. The mean-variance hedging problem in this incomplete bond-stock market for a contingent claim [Formula: see text] is solved by deriving an explicit solution of the optimal measure-valued strategy and the optimal cost induced by the optimal strategy of MHV for the stocks [Formula: see text] is computed.

Some generalized variability orderings among life distributions with reliability applications

1991 ◽  
Vol 28 (02) ◽  
pp. 374-383 ◽  
Author(s):  
M. C. Bhattacharjee
Keyword(s):  
Random Variables ◽  
Parallel Systems ◽  
Reliability Theory ◽  
Dominance Relation ◽  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
Closure Properties ◽  
Life Distributions ◽  
The Mean ◽  
Necessary And Sufficient

We investigate a generalized variability ordering and its weaker versions among non-negative random variables (lifetimes of components). Our results include a necessary and sufficient condition which justifies the generalized variability interpretation of this dominance relation between life distributions, relationships to some weakly aging classes in reliability theory, closure properties and inequalities for the mean life of series and parallel systems under such ordering.

STABILITY OF HALF-LINEAR NEUTRAL STOCHASTIC DIFFERENTIAL EQUATIONS WITH DELAYS

2009 ◽  
Vol 80 (3) ◽  
pp. 369-383 ◽  
Author(s):  
MENG WU ◽  
NAN-JING HUANG ◽  
CHANG-WEN ZHAO
Keyword(s):  
Fixed Point Theory ◽  
Point Theory ◽  
Stability Theorem ◽  
Sufficient Condition ◽  
Mean Square ◽  
Necessary And Sufficient Condition ◽  
Variable Delays ◽  
Mean Square Stability ◽  
The Mean ◽  
Necessary And Sufficient

AbstractIn this paper, we study the mean square asymptotic stability of a generalized half-linear neutral stochastic differential equation with variable delays applying fixed point theory. An asymptotic mean square stability theorem with a necessary and sufficient condition is proved, which improves and generalizes some results due to Burton, Zhang and Luo. Two examples are given to illustrate our results.

A note on the subcritical generalized age-dependent branching process

1976 ◽  
Vol 13 (04) ◽  
pp. 798-803
Author(s):  
R. A. Doney
Keyword(s):  
Branching Process ◽  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
Malthusian Parameter ◽  
Age Dependent ◽  
The Mean ◽  
Mean Function ◽  
Necessary And Sufficient

For a subcritical Bellman-Harris process for which the Malthusian parameter α exists and the mean function M(t)∼ aeat as t → ∞, a necessary and sufficient condition for e–at (1 –F(s, t)) to have a non-zero limit is known. The corresponding condition is given for the generalized branching process.

The performance of the move-to-front scheme under some particular forms of Markov requests

1995 ◽  
Vol 32 (04) ◽  
pp. 1089-1102 ◽  
Author(s):  
Eliane R. Rodrigues
Keyword(s):  
Stationary Distribution ◽  
Search Time ◽  
The Other ◽  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
Markov Dependence ◽  
The Mean ◽  
Necessary And Sufficient ◽  
The Way

The move-to-front scheme is studied taking into account some forms of Markov dependence for the way items are requested. One of the dependences specifically rules out two consecutive requests for the same item. The other is the so-called p-correlation. An expression for the stationary distribution of the sequence of arrangements of items is given in each case. A necessary and sufficient condition for these distributions to belong to a particular class of distributions is also given. The mean search time for an item is calculated for each form of dependence and these are compared with the value obtained in the case of independent requests. Some properties of the sequence of requests are given. Finally, an expression for the variance of the search time is obtained.

Some generalized variability orderings among life distributions with reliability applications

1991 ◽  
Vol 28 (2) ◽  
pp. 374-383 ◽  
Author(s):  
M. C. Bhattacharjee
Keyword(s):  
Random Variables ◽  
Parallel Systems ◽  
Reliability Theory ◽  
Dominance Relation ◽  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
Closure Properties ◽  
Life Distributions ◽  
The Mean ◽  
Necessary And Sufficient

We investigate a generalized variability ordering and its weaker versions among non-negative random variables (lifetimes of components). Our results include a necessary and sufficient condition which justifies the generalized variability interpretation of this dominance relation between life distributions, relationships to some weakly aging classes in reliability theory, closure properties and inequalities for the mean life of series and parallel systems under such ordering.

The performance of the move-to-front scheme under some particular forms of Markov requests

1995 ◽  
Vol 32 (4) ◽  
pp. 1089-1102 ◽  
Author(s):  
Eliane R. Rodrigues
Keyword(s):  
Stationary Distribution ◽  
Search Time ◽  
The Other ◽  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
Markov Dependence ◽  
The Mean ◽  
Necessary And Sufficient ◽  
The Way

The move-to-front scheme is studied taking into account some forms of Markov dependence for the way items are requested. One of the dependences specifically rules out two consecutive requests for the same item. The other is the so-called p-correlation. An expression for the stationary distribution of the sequence of arrangements of items is given in each case. A necessary and sufficient condition for these distributions to belong to a particular class of distributions is also given. The mean search time for an item is calculated for each form of dependence and these are compared with the value obtained in the case of independent requests. Some properties of the sequence of requests are given. Finally, an expression for the variance of the search time is obtained.

Computed Tomography-Based Patient-Specific Instrumentation Loses Accuracy with Significant Varus Preoperative Misalignment

2020 ◽  
Author(s):  
Vicente Jesús León-Muñoz ◽  
Mirian López-López ◽  
Alonso José Lisón-Almagro ◽  
Francisco Martínez-Martínez ◽  
Fernando Santonja-Medina
Keyword(s):  
Computed Tomography ◽  
Deformity Correction ◽  
Patient Specific ◽  
Control Group ◽  
X Rays ◽  
Varus Alignment ◽  
Patient Specific Instrumentation ◽  
Conventional Instrumentation ◽  
The Mean ◽  
Valgus Alignment

AbstractPatient-specific instrumentation (PSI) has been introduced to simplify and make total knee arthroplasty (TKA) surgery more precise, effective, and efficient. We performed this study to determine whether the postoperative coronal alignment is related to preoperative deformity when computed tomography (CT)-based PSI is used for TKA surgery, and how the PSI approach compares with deformity correction obtained with conventional instrumentation. We analyzed pre-and post-operative full length standing hip-knee-ankle (HKA) X-rays of the lower limb in both groups using a convention > 180 degrees for valgus alignment and < 180 degrees for varus alignment. For the PSI group, the mean (± SD) pre-operative HKA angle was 172.09 degrees varus (± 6.69 degrees) with a maximum varus alignment of 21.5 degrees (HKA 158.5) and a maximum valgus alignment of 14.0 degrees. The mean post-operative HKA was 179.43 degrees varus (± 2.32 degrees) with a maximum varus alignment of seven degrees and a maximum valgus alignment of six degrees. There has been a weak correlation among the values of the pre- and postoperative HKA angle. The adjusted odds ratio (aOR) of postoperative alignment outside the range of 180 ± 3 degrees was significantly higher with a preoperative varus misalignment of 15 degrees or more (aOR: 4.18; 95% confidence interval: 1.35–12.96; p = 0.013). In the control group (conventional instrumentation), this loss of accuracy occurs with preoperative misalignment of 10 degrees. Preoperative misalignment below 15 degrees appears to present minimal influence on postoperative alignment when a CT-based PSI system is used. The CT-based PSI tends to lose accuracy with preoperative varus misalignment over 15 degrees.

National primary standard of air kerma, air kerma rate, exposure, exposure rate and energy flux for X-rays and gamma radiation GET 8-2019

2020 ◽  
pp. 8-12
Author(s):  
Alexandr V. Oborin ◽  
Anna Y. Villevalde ◽  
Sergey G. Trofimchuk
Keyword(s):  
Gamma Radiation ◽  
Energy Flux ◽  
Primary Standard ◽  
Average Energy ◽  
Ion Pair ◽  
X Rays ◽  
Exposure Rate ◽  
Ionization Chambers ◽  
Air Kerma ◽  
Air Kerma Rate

The results of development of the national primary standard of air kerma, air kerma rate, exposure, exposure rate and energy flux for X-rays and gamma radiation GET 8-2011 in 2019 are presented according to the recommendations of the ICRU Report No. 90 “Key Data for Ionizing-Radiation Dosimetry: Measurement Standards and Applications”. The following changes are made to the equations for the units determination with the standard: in the field of X-rays, new correction coefficients of the free-air ionization chambers are introduced and the relative standard uncertainty of the average energy to create an ion pair in air is changed; in the field of gamma radiation, the product of the average energy to create an ion pair in air and the electron stopping-power graphite to air ratio for the cavity ionization chambers is changed. More accurate values of the units reproduced by GET 8-2019 are obtained and new metrological characteristics of the standard are stated.

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