Crossover Ratio Research Articles

Acetabular fracture types vary with different acetabular version

Acetabular fractures typically occur in high energy trauma. Understanding of the various contributing biomechanical factors and trauma mechanisms is still limited. While several investigations figured out what role femoral position during impact plays in distinct fracture patterns, no data exists on the influence of acetabular version on the fracture type. Our study was carried out to clarify this issue. Radiological data sets of 192 patients (145 male, 47 female, age 14-90years) sustaining acetabular fractures were assessed retrospectively. The crossover ratio of the crossover sign and presence or absence of the posterior wall sign and ischial spine sign were used to determine acetabular retroversion on conventional radiographs. Acetabular version in the axial plane was measured on a computed tomography (CT) scan. Statistics were then performed to analyse the relationship between the acetabular fracture type according to the Letournel classification and acetabular version. A significant difference (p = 0.029) in acetabular version was found between fractures of the anterior [mean equatorial edge (EE) angle 19.93°] and posterior (mean EE angle 17.53°) acetabulum in the CT scan. No difference was shown on the measurements on conventional radiographs. Acetabular version in the axial plane has an influence on the acetabular fracture pattern. While more anteverted acetabula were frequently associated with anterior fracture types according to the Letournel classification, retroversion of the acetabulum was associated with posterior fracture types.

Classical Genetics Meets Next-Generation Sequencing: Uncovering a Genome-Wide Recombination Map in Drosophila melanogaster

Classical Genetics Meets Next-Generation Sequencing: Uncovering a Genome-Wide Recombination Map in Drosophila melanogaster

Correlation between radiographic measures of acetabular morphology with 3D femoral head coverage in patients with acetabular retroversion

Background and purpose Acetabular retroversion may result in anterior acetabular over-coverage and posterior deficiency. It is unclear how standard radiographic measures of retroversion relate to measurements from 3D models, generated from volumetric CT data. We sought to: (1) compare 2D radiographic measurements between patients with acetabular retroversion and normal control subjects, (2) compare 3D measurements of total and regional femoral head coverage between patients and controls, and (3) quantify relationships between radiographic measurements of acetabular retroversion to total and regional coverage of the femoral head.Patients and methods For 16 patients and 18 controls we measured the extrusion index, crossover ratio, acetabular angle, acetabular index, lateral center edge angle, and a new measurement termed the “posterior wall distance”. 3D femoral coverage was determined from volumetric CT data using objectively defined acetabular rim projections, head-neck junctions, and 4 anatomic regions. For radiographic measurements, intra-observer and inter-observer reliabilities were evaluated and associations between 2D radiographic and 3D model-based measures were determined.Results Compared to control subjects, patients with acetabular retroversion had a negative posterior wall distance, increased extrusion index, and smaller lateral center edge angle. Differences in the acetabular index between groups approached statistical significance. The acetabular angle was similar between groups. Acetabular retroversion was associated with a slight but statistically significant increase in anterior acetabular coverage, especially in the anterolateral region. Retroverted hips had substantially less posterior coverage, especially in the posterolateral region.Interpretation We found that a number of 2D radiographic measures of acetabular morphology were correlatedwith 3D model-based measures of total and regional femoral head coverage. These correlations may be used to assist in the diagnosis of retroversion and for preoperative planning.

Management of Asymptomatic Inguinal Hernia

To establish a literature-based surgical approach to asymptomatic inguinal hernia (IH). PubMed, the Cochrane Library database, Embase, national guidelines (including the National Library of Guidelines Specialist Library), National Institute for Health and Clinical Excellence guidelines, and the National Research Register were searched for prospective randomized trials comparing surgical treatment of patients with asymptomatic IH with conservative treatment. The literature search retrieved 216 article headlines, and these articles were analyzed. Of those studies, a total of 41 articles were found to be relevant and 2 large well-conducted randomized controlled studies that published their results in several articles were reviewed. The pain and discomfort, general health status, complications, and life-threatening events of patients with asymptomatic IH managed by surgery or watchful waiting were determined. No significant difference in pain scores and general health status were found when comparing the patients who were followed up with the patients who had surgery. A significant crossover ratio ranging between 23% and 72% from watchful waiting to surgery was found. In patients with watchful waiting, the rates of IH strangulation were 0.27% after 2 years of follow-up and 0.55% after 4 years of follow-up. In patients who underwent elective surgery, the range of operative complications was 0% to 22.3% and the recurrence rate was 2.1%. Both treatment options for asymptomatic IH are safe, but most patients will develop symptoms (mainly pain) over time and will require operation.

A major recombination hotspot in the XqYq pseudoautosomal region gives new insight into processing of human gene conversion events

Recombination plays a fundamental role in meiosis. Non-exchange gene conversion (non-crossover, NCO) may facilitate homologue pairing, while reciprocal crossover (CO) physically connects homologues so they orientate appropriately on the meiotic spindle. In males, X-Y homologous pairing and exchange occurs within the two pseudoautosomal regions (PARs) together comprising <5% of the human sex chromosomes. Successful meiosis depends on an obligatory CO within PAR1, while the nature and role of exchange within PAR2 is unclear. Here, we describe the identification and characterization of a typical ~1 kb wide recombination hotspot within PAR2. We find that both COs and NCOs are strongly modulated in trans by the presumed chromatin remodelling protein PRDM9, and in cis by a single nucleotide polymorphism (SNP) located at the hotspot centre that appears to influence recombination initiation and which causes biased gene conversion in SNP heterozygotes. This, the largest survey to date of human NCOs reveals for the first time substantial inter-individual variation in the NCO:CO ratio. Although the extent of biased transmission at the central marker in COs is similar across men, it is highly variable among NCO recombinants. This suggests that cis-effects are mediated not only through recombination initiation frequencies varying between haplotypes but also through subsequent processing, with the potential to significantly intensify meiotic drive of hotspot-suppressing alleles. The NCO:CO ratio and extent of transmission distortion among NCOs appear to be inter-related, suggesting the existence of two NCO pathways in humans.

A Critical Size Ratio for Viscosity Reduction in Poly(dimethylsiloxane)−Polysilicate Nanocomposites

The zero-shear-rate viscosity η0 of polymer−nanocomposites (PNCs) derived from entangled poly(dimethylsiloxane)s and rigid polysilicate nanoparticles were investigated as a function of molecular size and concentration. Narrow molecular weight fractions of polymer and nanoparticle were obtained by supercritical fluid extraction. Molecular weight properties were analyzed by size exclusion chromatography and the nanoparticle radius of gyration Rg was characterized by small-angle neutron scattering. All seven polysilicate fractions were smaller (0.75 ≤ Rg, nm ≤ 2.1) than the five polymers (3.0 ≤ Rg, nm ≤ 12). Relative to the polymer η0 the PNC η0 exhibited either plasticization (viscosity reduction) or reinforcement (viscosity increase). Only reinforcement was observed in PNCs based on the polymer below Mc—the critical molecular weight for chain entanglement effects to start influencing η0—which included an increase in the PNC η0 by over 3 orders of magnitude using 0.30 volume fraction of the largest nanoparticle. For polymers above Mc, the crossover from plasticization to reinforcement behavior could be described by a critical molecular-size ratio based on the unperturbed Rg of the nanoparticle and of the polymer. Viscosity reductions of up to 52% were achieved, and were more significant at the higher of the two nanoparticle concentrations studied. The critical nanoparticle-to-polymer Rg ratio at 298 K was 0.18 ± 0.006 and 0.13 ± 0.003 for a nanoparticle volume fraction of 0.17 and 0.30, respectively. A generalized form for the concentration dependent crossover ratio is proposed to account for perturbations in the molecular size of the PNC components that can be the basis for future studies. The effects of particle size polydispersity and temperature are discussed.

Correlation of the cross-over ratio of the cross-over sign on conventional pelvic radiographs with computed tomography retroversion measurements

To find a correlation between the cross-over ratio of the cross-over sign on conventional anteroposterior (AP) pelvic radiographs and retroversion measurements ('roof-edge angle' and 'equatorial-edge angle) on computed tomography (CT) scans. This would facilitate the interpretation of the cross-over sign regarding the amount of acetabular retroversion. Correctly projected AP pelvic radiographs (2,925 hips) were examined for the presence of the cross-over sign (COS), and the overlap ratio of the COS was measured. On CT scans of the same patients the 'roof-edge angle' (RE angle) and the 'equatorial-edge angle' (EE angle) were also calculated. A statistically significant but only weak relationship could be found between the overlap ratio of the COS and the 'roof-edge angle' (P < 0.0001; correlation coefficient -0.486) and between this ratio and the 'equatorial-edge angle' (P < 0.0001; correlation coefficient -0.395). A relationship between the overlap ratio and orientation measurements on CT scans could be found, but it was less strong than expected.

Prevalence of acetabular dome retroversion in a mixed race adult trauma patient population.

The goals of the present investigation were to identify the prevalence of acetabular dome retroversion in a mixed race population, to quantify the average amount of cross-over ratio, and to determine normative values. The presence of the cross-over sign and its overlap ratio was assessed for 2,925 hips meeting strict radiographic criteria of the pelvic radiograph. Fifty-two percent of the hips had no cross-over sign whereas 48% had at least a minimal amount of overlap of the anterior and posterior acetabular wall. Analysis of only those hips with positive cross-over sign revealed a mean cross-over ratio of 26% +/- 11% (range: 3 to 93). Forty-two percent of the patients had no cross-over on either side, 18% on one side, and 40% on both sides. The presence of the cross-over sign is more common than previously expected. Further studies will be necessary to determine the risk of pathological abnormality and to correlate symptoms to crossover ratios. Surgery should not be based solely on the finding of a cross-over sign without clinical correlation.

Optimum operating strategies for liquid-fed direct methanol fuel cells

This study focuses on optimum operating strategies for liquid-fed direct methanol fuel cells (DMFCs) to minimize methanol consumption. A mathematical model is developed and verified with experimental data from the literature using the parameter estimation method. The model consists of a set of differential and algebraic equations and makes it possible to describe zero initial hold-up conditions. Based on the model, steady-state simulation results are obtained and explain the dependence on the feed concentration of key variables such as cell voltage, cell power density, overpotentials of both electrodes, and methanol crossover ratio. Dynamic simulation results are also presented to check the transient behaviour of a DMFC operated from start-up to shut-down. Dynamic optimization allows determination of the optimum transient strategies of feed concentration required to maximize the fuel efficiency. With six scenarios of power density load, it is demonstrated that the optimum transient strategies depend heavily on both the load of power density and the number of control actions. The main advantage of these approaches is to reduce fuel consumption and, ultimately, to enable DMFCs to be operated more efficiently.

Analysis of a FBG sensing system with transverse uniform press by using genetic algorithm

An analytical method in a quasi-static fiber grating sensing system under transverse uniform press is proposed based on genetic algorithm The effect of population size, generations, crossover ratio and mutation ratio to genetic algorithm, and the optimization parameters of genetic algorithm were given. The relevant experimental system is constructed. The simulation and experiments show that the analytical method proposed can be applied to analyze the reflective spectra of the quasistatic FBG sensing system at transverse uniform press, the strain measurement with high-precision of 0.91% can be realized

Various hybrid methods based on genetic algorithm with fuzzy logic controller

In this paper we propose several efficient hybrid methods based on genetic algorithms and fuzzy logic. The proposed hybridization methods combine a rough search technique, a fuzzy logic controller, and a local search technique. The rough search technique is used to initialize the population of the genetic algorithm (GA), its strategy is to make large jumps in the search space in order to avoid being trapped in local optima. The fuzzy logic controller is applied to dynamically regulate the fine-tuning structure of the genetic algorithm parameters (crossover ratio and mutation ratio). The local search technique is applied to find a better solution in the convergence region after the GA loop or within the GA loop. Five algorithms including one plain GA and four hybrid GAs along with some conventional heuristics are applied to three complex optimization problems. The results are analyzed and the best hybrid algorithm is recommended.

Genetic algorithm with fuzzy logic controller for preemptive and non-preemptive job-shop scheduling problems

In this paper, we propose a new genetic algorithm (GA) with fuzzy logic controller (FLC) for dealing with preemptive job-shop scheduling problems (p-JSP) and non-preemptive job-shop scheduling problems (np-JSP). The proposed algorithm considers the preemptive cases of activities among jobs under single machine scheduling problems. For these preemptive cases, we first use constraint programming and secondly develop a new gene representation method, a new crossover and mutation operators in the proposed algorithm. However, the proposed algorithm, as conventional GA, also has a weakness that takes so much time for the fine-tuning of genetic parameters. FLC can be used for regulating these parameters. In this paper, FLC is used to adaptively regulate the crossover ratio and the mutation ratio of the proposed algorithm. To prove the performance of the proposed FLC, we divide the proposed algorithm into two cases: the GA with the FLC (pro-fGA) and the GA without the FLC (pro-GA). In numerical examples, we apply the proposed algorithms to several job-shop scheduling problems and the results applied are analyzed and compared. Various experiments show that the results of pro-fGA outperform those of pro-GA.

A study on schema preservation by crossover

AbstractThis paper considers the combinatorial optimization problem in which the solution (sample) can be decomposed linearly into multiple schemata. Focusing on an arbitrary kind of schema, the schema preservation mechanism of the crossover in the genetic algorithm is discussed from the viewpoint of the increase or decrease of the number of samples (considered samples) containing the considered schema in the set of sample bit strings. It is shown that the change in the number of considered samples with time is divided into two kind of phases (stable and unstable phases), depending on whether or not there exists a point of equilibrium for increase and decrease in copying during the course of selection, and for degradation by destruction in crossover and mutation. It is shown that the transition between the stable phase and the unstable phase occurs according to the magnitude relation between the average fitness of the considered samples and the average fitness of the whole set of sample bit strings. By setting the crossover ratio as a higher value in the genetic algorithm, the schema is uniformly embedded in the whole set of sample bit strings, which increases the average fitness of the considered samples, and generates an equilibrium point that maintains a constant number of considered samples. Lastly, a computer simulation is performed, and it is shown that the discussion of the schema preservation mechanism of the crossover is adequate. © 2002 Scripta Technica, Syst Comp Jpn, 33(2): 64–76, 2002

RANKING REVERSAL OF PROJECTS WITH DIFFERENT RISKS AND LIVES

Abstract This paper shows that standard techniques for comparing mutually exclusive projects with different lives and different risks are flawed. In this case, the superiority of a project may not be maintained over all common horizons since rankings of net present values (NPV's) can reverse at some time. A new method, the crossover ratio test, is presented to determine whether an NPV ranking reversal occurs upon replication. It offers accept/reject decisions and rankings consistent with NPV methods while correctly accounting for differences in risk. Also, a method is described for locating the exact point when the crossover of NPV's occurs.

New exact diagram approach to the Kondo problem

Described is the physics behind an new exact Feynman diagram approach to the Kondo problem. The method corresponds to a certain self-consistent parquet approximation. Here relatively simple arguments are used to justify the diagram results. The calculation of the static susceptibility and specific heat is described. The cross-over ratio W′=( π e ) 1 2 and Wilson ratio R=2 are given exactly.

Erratum

Abstract In the article "Expression and Linkage of Genes for X-linked Hemophilias A and B in the Dog" by Brinkhous et al. (Blood, Vol. 41, No. 4, April 1973, pp. 577-585) the following items should read as given below: Page 579, paragraph 3, Results Once doubly heterozygous adult females were available, they were bred to determine the recombination frequency among the progeny. The sires were of the three phenotypes: normal, hemophilia A, and hemophilia B. The results from 15 litters, with 78 tested progeny, are shown in Table 2. The male:female ratio was 33:45 (x2 = 2.45; p &gt; 0.10). From these matings, four male genotypes are possible, and all were observed. The crossover ratio was 15:18 in males, suggesting a deficiency of doubly hemophilic males (aXbY) from the XY · aXXb and aXY · aXXb matings. Page 579, paragraph 5, Results The ratio of crossovers to noncrossovers for all progeny, both male and females, of the double heterozygotes is 41:37. This is so close to the maximum 50% frequency of 39:39 that the linkage distance is too great to be measured. Page 580, Table 2, line 4, Genotype of Noncrossover Females, should read aXXb. Page 584, first paragraph at top of page, the last sentence is: These data thus suggest that X-inactivation was indeed random, without respect to the paternal or maternal source of the X-chromosome.

Decay ofGa66andCu66

The 9.5-hour decay of ${\mathrm{Ga}}^{66}$ and the 5.1-minute decay of ${\mathrm{Cu}}^{66}$ have been studied by a variety of techniques including gamma-ray spectroscopy, internal conversion measurements, and angular correlation studies. All but one of the 18 gamma rays observed have been ordered into a structure of 11 levels and the spins and parities of all but one of these levels have been determined. It is shown that ${\mathrm{Ga}}^{66}$ has spin zero and even parity and that its 4.166-Mev $\ensuremath{\beta}$ spectrum is a pure Fermi transition. The energy of the internal conversion line of the 4.300\ifmmode\pm\else\textpm\fi{}0.005 Mev transition was measured with great care and this line may be useful for spectrometer calibration. The second excited state of ${\mathrm{Zn}}^{66}$, at 1.875 Mev, has 2+ spin and parity. The stopover transition from this state contains at least 10% $M1$ radiation: the stopover to crossover ratio is greater than 100 to 1.

New Experiences with Oenothera Mut. Pollicata

(1) Oenothera mut. pollicata, which is distinguished by a solid hypanthium intervening between the distal end of the ovary and the proximal end of the style, recurred unexpectedly in 1934 in eight different families. Five of these families were from Lamarckiana-like parents and three from erythrina-like parents. (2) The distribution with respect to other segregating traits showed that mut. pollicata is independent of genes of the third linkage group and closely linked with genes of the first linkage group. (3) The presence of the well-known zygote lethals in the first linkage group conditions the manifestation of pollicata just as it does that of other first-linkage-group recessives. In progenies from selfed heterozygotes of Lamarckiana type, pollicata can appear only as the result of a transfer from the gaudens to the velans complex or vice versa. In the five progenies here reported from Lamarckiana parents, there were 466 non-pollicata and 7 pollicata, indicating a frequency of crossing over of the general order of 1.5 per cent. (4) In three families from erythrina-like parents, there was the usual segregation of erythrina and decipiens, in which all decipiens plants were pollicata, and all but one of the erythrina-like segregates had normal tubular hypanthia. In these three families there was a total of 403 plants, only one of which could be recognized certainly as a crossover, thus suggesting a crossover ratio of the general order of 0.25 per cent. (or of 0.5 per cent. if a narrow-leafed pollicata mutant be also assumed to have resulted from crossing over). (5) The occurrence of these new examples of mut. pollicata is supposed to be due to the unsuspected presence of the pollicata gene, generally, in those families which were derived from a common pair of ancestors in the cultures of 1928, but it is more difficult to believe they could have escaped detection through the fourteen generations required to connect all these families. It is deemed more probable that the pollicata gene-mutation has been repeated. (6) The pollicata gene removes an inhibition of growth at the top of the ovary in a narrow concentric ring separating the proximal portion of the style from the proximal portion of the hypanthium. It also diminishes the longitudinal growth of the hypanthium relative to that of ovary and bud-cone, and modifies the differentiation of mechanical tissue in the style. (7) The interpolation of a solid stem-like structure between the distal end of the ovary and the proximal end of the style as the result of a gene mutation makes easier an understanding of the manner in which different genera, families, orders, etc., may have originated.