Crossover Pattern Research Articles

Development and validation of Decisional Balance and Temptations measures for Bulgarian adolescent smokers

The goal of this study was to develop measures for Decisional Balance and Situational Temptations for Bulgarian adolescent smokers and to test predicted theoretical relationships with Stages of Change in the same population. Consistent with previous findings for other populations, a 3-factor model for Decisional Balance (CFI = .95) and a hierarchical 4-factor model for Temptations (CFI = .90) best fit the data. The predicted crossover pattern for Decisional Balance and a decreasing trend for Temptations across the Stages of Change were verified. Both measures demonstrated good levels of factorial invariance across gender and across random split-half cross-validation samples. These results support the cross-cultural validity of the TTM constructs and indicate that they can be used as a basis for development of interventions for the population under study.

Ordering and elasticity associated with low-temperature phase transitions in lawsonite

The two low-temperature phase transitions of lawsonite have been studied using single-crystal X-ray diffraction from 86 to 318 K and a single-crystal high-frequency continuous-wave resonance technique from 323 to 102 K. While recently published data of the variations of strains, birefringence, and IR line widths are consistent with the (271 K) Cmcm-Pmcn transition being simply tricritical, our investigation of critical X-ray refl ections and the six diagonal elastic constants of lawsonite reveals, consistently, a more complex crossover pattern in the temperature range of 205–225 K. Below 205 K the overall pattern is again in good agreement with a tricritical solution of the Cmcm-Pmcn transition and a second-order behavior of the (120 K) Pmcn-P21cn transition. The structure determination from single-crystal X-ray data at 215 K reveals a possible orientational disorder of some of the hydroxyl groups in the Pmcn phase. From this and a recent strain analysis of deuterated and hydrogenated lawsonite we conclude that down to 205 K the Cmcm-Pmcn transition is driven by a displacive component, as observed in strain and birefringence data, plus an order/disorder component or dynamical effects associated with proton ordering. Below 205 K only the displacive component plays a role, and the (120 K) Pmcn-P21cn transition is driven by a single order parameter. The remarkable elastic softening of C66 ahead of the Cmcm-Pmcn transition indicates another orthorhombic-monoclinic transition, which is suppressed on cooling through the low-temperature phase sequence Cmcm-Pmcn-P21cn, but can be observed on applying pressure to the mineral.

Changes in crossover distribution along a quadrivalent in a man carrier of a reciprocal translocation t(11;14)

A testicular biopsy from an infertile man carrying a heterozygous chromosome translocation t(11;14) was studied with synaptonemal complex analysis and immunolocalization of the protein MLH1 for crossover detection. A full blockage of spermatogenesis at the spermatocyte stage was related to the presence of the translocation quadrivalents at pachytene. Only 2% of the quadrivalents showed full synapsis. Most of the spermatocytes showed asynaptic free ends that frequently mingled with the XY pair. The average number of crossovers per cell was diminished from a mean of 52.7 in controls to a mean of 48 in the patient. The difference between the number of crossovers in the quadrivalent and the normal bivalents was highly significant. The distribution of crossovers over the segment of the quadrivalent corresponding to bivalent #14 was also very different from that of the control. It is concluded that in this translocation, the pattern of crossovers is changed, mainly due to a synaptic hindrance in the quadrivalent, and that the spermatogenesis arrest is mainly due to the quadrivalents that interact with the XY pair.

Crossover from Poisson to Wigner-Dyson level statistics in spin chains with integrability breaking

We study numerically the evolution of energy-level statistics as an integrability-breaking term is added to the XXZ Hamiltonian. For finite-length chains, physical properties exhibit a cross-over from behavior resulting from the Poisson level statistics characteristic of integrable models to behavior corresponding to the Wigner-Dyson statistics characteristic of the random-matrix theory used to describe chaotic systems. Different measures of the level statistics are observed to follow different crossover patterns. The range of numerically accessible system sizes is too small to establish with certainty the scaling with system size, but the evidence suggests that in a thermodynamically large system an infinitesimal integrability breaking would lead to Wigner-Dyson behavior.

Inhibition of return in children and adolescents

Inhibition of return (IOR), slowed responding to targets at a cued location after attention is removed from this location, has been shown to occur both in adults and in infants. To explore Klein’s (2000) suggestion that the timecourse of IOR depends on factors that might affect the efficiency with which attention is removed from the cued location, we compared the performance of young children (5–10-year-olds, N=49, M=8 years, 4 months) to older children and adolescents (11–17-year-olds, N=61, M=14 years) in single and double cue procedures. Cue-target interval was varied to measure the timecourse of IOR in this within-subjects localization task. Whereas no IOR was found in the young group unless a double cue procedure was used, in the older group, we found IOR at all intervals with the double cue procedure and the typical crossover pattern (cf., Posner & Cohen, 1984), with early facilitation followed by inhibition in the single cue procedure.

Plant Zinc and the Zinc‐Efficiency Trait in Navy Bean

Seed of zinc (Zn)‐efficient and Zn‐inefficient navy bean (Phaseolus vulgaris L.) genotypes differ in Zn concentration [Zn]. Greenhouse studies were conducted to determine how Zn and P fertilizers influence seed [Zn] and within‐plant distribution of Zn in the navy bean genotypes Voyager (Zn‐efficient) and Albion (Zn‐inefficient). Addition of 60 and 120 mg P kg−1 in the absence of added Zn to a Calciaquoll low in available P and Zn decreased seed yields of Albion by 18 and 59%, respectively, but increased seed yields of Voyager by 32 and 41%, respectively. However, addition of fertilizer P with 4 mg Zn kg−1 increased seed yields of both genotypes. Seed [Zn] was generally higher in Voyager than in Albion, was increased by Zn fertilizer, and decreased by P fertilizer. In a follow‐up experiment seed [Zn] of Voyager and Albion converged as fertilizer Zn was increased from 8 to 64 mg kg−1. In contrast to seed [Zn], leaf, stem and pod‐wall [Zn] of Albion at maturity were higher than those of Voyager at elevated levels of fertilizer Zn. This crossover pattern for maternal‐plant [Zn] at maturity also occurred in shoots of 18‐d‐old plants. Differences in seed [Zn] between the two genotypes were generally most pronounced when Albion contained greater than 20 and less than 35 mg kg−1 of seed [Zn]. Seed [Zn] is superior to leaf and stem [Zn] for selection of Zn‐efficient navy bean genotypes in plant breeding research.

Crossovers in seedling relative growth rates between low and high irradiance: analyses and ecological potential

Crossovers in seedling relative growth rates between low and high irradiance: analyses and ecological potential

The Relationship Between Daily Marital Interaction, Work, and Health-Promoting Behaviors in Dual-Earner Couples

This article examines the spillover and crossover patterns between an individual’s daily work experiences and health-promoting behaviors and daily marital interaction in 49 dual-earner couples. Husbands and wives separately completed daily diaries that included questions about work experiences, health-promoting behaviors, and marital interactions over 42 consecutive days. Pooled time series regression analyses were performed to examine transmission patterns between daily individual experiences and marital interaction. Spillover patterns were demonstrated from both individual experiences to marital interaction the same day and from marital interaction to individual experiences the next day. In general, spouses reported more positive marital interaction on days when they worked less, felt more energetic, ate more, and relaxed more. Spouses also reported working, eating, and relaxing more on days after husbands’ negative marital interaction was reported. Patterns of spillover also differed for husbands and wives, suggesting that wives may be more reactive to their husbands’ experiences and behaviors than vice versa.

Correlation differences in heartbeat fluctuations during rest and exercise.

We study the heartbeat activity of healthy individuals at rest and during exercise. We focus on correlation properties of the intervals formed by successive peaks in the pulse wave and find significant scaling differences between rest and exercise. For exercise the interval series is anticorrelated at short-time scales and correlated at intermediate-time scales, while for rest we observe the opposite crossover pattern--from strong correlations in the short-time regime to weaker correlations at larger scales. We also suggest a physiologically motivated stochastic scenario to provide an intuitive explanation of the scaling differences between rest and exercise.

Apparent Mineral Retention Is Similar in Control and Hyperinsulinemic Men after Consumption of High Amylose Cornstarch

The effects on apparent mineral retention after long-term consumption of a high amylose diet containing 30 g resistant starch (RS) were investigated in 10 control and 14 hyperinsulinemic men. Subjects consumed products (bread, muffins, cookies, corn flakes and cheese puffs) made with standard (70% amylopectin, 30% amylose; AP) or high amylose (70% amylose, 30% amylopectin; AM) cornstarch for two 14-wk periods in a crossover pattern. Starch products replaced usual starches in the habitual diet for 10 wk followed by 4 wk of consuming the controlled diets. During wk 12, all urine, feces and duplicate foods were collected for 7 d. Urinary chromium losses after a glucose tolerance test or 24-h collections of the hyperinsulinemic and control subjects did not differ and were not altered by diet. Except for zinc, the two subject types did not differ significantly in apparent mineral balance. Apparent retentions of calcium and magnesium were not significantly affected by diet (AM vs. AP) or type-by-diet interaction. Apparent iron retention tended to be greater after AM than AP consumption (P < 0.09). Apparent copper retention was greater after consuming AP than after AM (P < 0.02), whereas apparent zinc retention was greater after consuming AM than after AP (P < 0.018). Zinc also showed a significant type-by-diet interaction (P < 0.034) with control subjects retaining less zinc after consuming AP than after AM. In summary, a high amylose cornstarch diet containing 30 g RS could be consumed long term without markedly affecting, and possibly enhancing, retention of some minerals.

The biogeochemistry of sulfur at Hubbard Brook

A synthesis of the biogeochemistry of S was done during 34 yr (1964-1965 to 1997-1998) in reference and human-manipulated forest ecosystems of the Hubbard Brook Experimental Forest (HBEF), NH. There have been significant declines in concentration (0.44 mol/liter-yr) and input (5.44 mol/ha-yr) of SO4 in atmospheric bulk wet deposition, and in concentration (0.64 mol/liter-yr) an d output (3.74 mol/ha-yr) of SO4 in stream water of the HBEF since 1964. These changes are strongly correlated with concurrent decreases in emissions of SO2 from the source area for the HBEF. The con- centration and input of SO4 in bulk deposition ranged from a low of 13.1 mol/liter (1983-1984) and 211 mol/ha-yr (1997-1998) to a high of 34.7 mol/liter (1965-1966) and 479 mol/ha-yr (1967-1968), with a long-term mean of 23.9 mol/liter and 336 mol/ha-yr during 1964-1965 to 1997-1998. Despite recent declines in concentrations, SO4 is the dominant anion in both bulk deposition and stream water at HBEF. Dry deposition is difficult to measure, especially in mountainous terrain, but was estimated at 21% of bulk deposition. Thus, average total atmospheric deposition was 491 and 323 mol/ha-yr during 1964-1969 and 1993-1998, respectively. Based on the long-term 34 S pattern associated with anthro- pogenic emissions, SO4 deposition at HBEF is influenced by numerous SO2 sources, but biogenic sources appear to be small. Annual throughfall plus stemflow in 1993-1994 was estimated at 346 mol SO4 /ha. Aboveground litterfall, for the watershed-ecosystem averaged about 180 mol S/ha-yr, with highest inputs (190 mol S/ha-yr) in the lower elevation, more deciduous forest zone. Weathering release was calculated at a maximum of 50 mol S/ha-yr. The concentration and output of SO4 in stream water ranged from a low of 42.3 mol/liter (1996-1997) and 309 mol/ha-yr (1964-1965), to a high of 66.1 mol/liter (1970-1971) and 849 mol/ha-yr (1973-1974), with a long-term mean of 55.5 mol/liter and 496 mol/ha-yr during the 34 yrs of study. Gross outputs of SO4 in stream water consistently exceeded inputs in bulk deposition and were positively and significantly related to annual precipitation and streamflow. The relation between gross SO4 output and annual streamflow changed with time as atmo- spheric inputs declined. In contrast to the pattern for bulk deposition concentration, there was no sea- sonal pattern for stream SO4 concentration. Nevertheless, stream outputs of SO4 were highly sea- sonal, peaking during spring snowmelt, and producing a monthly cross-over pattern where net hydro- logic flux (NHF) is positive during summer and negative during the remainder of the year. No significant elevational pattern in streamwater SO4 concentration was observed. Mean annual, volume-weighted

Nonadiabatic instanton calculation of multistate electron transfer reaction rate: Interference effects in three and four states systems

For multistate electron transfer reactions with quantum reaction coordinates, nonadiabatic instanton theory can provide a powerful and direct means of calculating the reaction rate without any limitation to the magnitudes of electronic coupling constants. In order to examine its performance in detail, the theory is applied to simple model systems with three and four electronic states which have one and two bridge states respectively. Calculations for three states systems, varying the through–bond coupling constant, show that the nonadiabatic instanton theory reproduces the results of perturbation and adiabatic instanton theories in the limits of small and large coupling constants, respectively. In the absence of through–space coupling, the crossover between the two limits is smooth and monotonic. However, in the presence of through–space coupling, the crossover pattern becomes sensitive to the relative phase of the two electronic channels and demonstrates substantial interference effects. For a four states system that has two interfering through–bond coupling paths, similar interference effect was observed. These results show that the nonadiabatic instanton method can serve as a favorable means of understanding the general kinetics and exploring the interference effects in the low-temperature bridge mediated and/or proton coupled electron transfer systems.

Integrated multilayer high-T/sub c/ SQUID magnetometers with slotted washer

We have fabricated and characterized multilayer high-T/sub c/ SQUID magnetometers designed for a magnetically unshielded environment. The magnetometers consist of YBa/sub 2/Cu/sub 3/O/sub 7-x/(YBCO)/SrTiO/sub 3/(STO)/YBCO trilayers deposited by pulsed laser deposition (PLD) on an STO bi-crystal substrate. We fabricated SQUIDs with slotted washers at the bottom or top YBCO layer. The slots consist of 4 /spl mu/m wide superconducting lines separated by 8 /spl mu/m. A flux transformer with a multi-turn input coil was defined on the top or bottom YBCO layer, and the SQUID washer was used as a crossover pattern to simplify the fabrication process. The pickup loop size was 4 mm/spl times/7 mm, and the magnetometer effective area was found to be 0.67 mm/sup 2/. The SQUID inductance was 85 pH. For the operation of our SQUID in unshielded environments, compact 3 MHz modulation flux locked loop (FLL) electronics with bias-reversal were developed. The system bandwidth was greater than 500 kHz, and maximum slew rate was about 10/sup 6/ /spl Phi//sub 0//sec. The flux noise spectra of the magnetometers were measured and compared with our single layer devices. We also investigated the effect of slots on the coupling strength between the input coil and SQUID.

Nifedipine or prazosin as a second agent to control early severe hypertension in pregnancy: a randomised controlled trial

To determine whether nifedipine or prazosin is the more appropriate second-line antihypertensive agent in pregnancy. Randomised controlled trial. Tygerberg Hospital, a tertiary referral centre. Women with early, severe pre-eclampsia or hypertension in pregnancy, whose blood pressure could not be adequately controlled by methyldopa 2 g/day, but were otherwise stable. Nifedipine or prazosin were given and increased as necessary in a stepwise fashion. Once the maximum dose was reached, the other drug was added in a crossover pattern. Failure to control blood pressure, or the onset of maternal/fetal complications were indications for delivery. Patients reaching a minimum gestation of 34 weeks without complications were delivered electively. Antenatal days gained; major maternal complications and perinatal survival. Days gained on the second antihypertensive agent did not differ significantly (P = 0.9), while more days were gained using nifedipine as the crossover 'third agent' (P = 0.01). In the nifedipine group better renal function was recorded, but more cases with isolated low platelet counts occurred. More cases of pulmonary oedema as well as more nonviable mid-trimester and third trimester intrauterine deaths occurred in the prazosin group. Nifedipine and prazosin as second agents allowed comparable amounts of time to be gained, although this changed when used as crossover third-line agents. The efficacy and safety of nifedipine in this study are consistent with the results of other studies. A greater number of intrauterine deaths occurred in the prazosin group.

High resolution analysis of haplotype diversity and meiotic crossover in the human TAP2 recombination hotspot.

Little is known about the nature of recombination hotspots in the human genome and the relationship between crossover activity and patterns of linkage disequilibrium. We have therefore used both haplotype analysis and direct detection of crossovers in sperm to characterize a putative recombination hotspot in the TAP2 gene within the class II region of the MHC. Haplotype diversity provided evidence for a localized hotspot within intron 2 of this gene. Sperm DNA typing using allele-specific PCR primers to selectively amplify recombinant TAP2 molecules revealed a highly localized meiotic crossover hotspot approximately 1.2 kb long, unusually abundant in sequence polymorphisms and flanked by DNA much less active in recombination. Sperm crossover appeared to be fully reciprocal, and almost all crossover products were simple, involving a single exchange between adjacent heterozygous markers. This hotspot appears to be much more active in female than male meiosis. No primary sequence similarities could be found between any of the very few well defined crossover hotspots in the human genome, all of which show recombinationally active domains 1-2 kb long. Direct comparison of recombination frequency and haplotype diversity in TAP2 showed that linkage disequilibrium measures were a poor predictor of crossover frequency in this region, with non-recombining markers sometimes in free association and with examples of pairs of markers spanning the recombination hotspot showing substantial or even absolute linkage disequilibrium.

Genetic Recombination of Poliovirusin Vitroandin Vivo: Temperature-Dependent Alteration of Crossover Sites

Genetic recombination that occurs with high frequency during poliovirus genome replication is a process whose molecular mechanism is poorly understood. Studies of genetic recombination in a cell-free systemin vitroand in infected tissue culture cellsin vivohave led to the unexpected observation that temperature strongly influences the loci at which cross-over between the two recombining RNA strands occurs. Specifically, cross-over between two genetically marked RNA strandsin vitroandin vivoat 34°C occurred over a wide range of the genome. In contrast, recombinationin vivoat 37 and 40°C yielded cross-over patterns that had shifted dramatically to a region encoding nonstructural proteins. Preferential selection of recombinants at 37 and 40°C was ruled out by analyses of the growth kinetics of the recombinants. During the studies of recombination in the cell-free system we found that there is a direct correlation between the ability of a poliovirus RNA molecule to replicate in the cell-free system and its capacity to complementde novovirus synthesis programmed by another viral RNA.

Positive and negative schizotypal symptoms relate to different aspects of crossover reaction time task performance

Although the expressions of both positive and negative symptoms in schizophrenia spectrum illnesses can each occur with varying degrees of severity, researchers have often dichotomized patients as generally positive or negative subtypes. Studies of schizophrenia and schizotypal personality disorder (SPD) have not typically controlled for the severity of the other symptom types when examining the relationship between positive and negative symptom subtypes and cognitive impairment. The present study investigated the relationship between the severity of both symptom types and reaction time crossover task performance in SPD in groups made equivalent on the severity of the other type of symptom. Fifty-eight out of 458 undergraduates were screened into one of four groups (high negative-high positive, low negative-low positive, high negative-low positive or low negative-high positive) by the Schizotypal Personality Questionnaire and assessed with the reaction time crossover task. The results indicated that negative schizotypal symptoms were associated with the early crossover pattern, while positive schizotypal symptoms related to longer overall reaction time. Therefore, different cognitive mechanisms involved in crossover task performance appeared to be associated with different symptom subtypes.

Breath Hydrogen and Methane Expiration in Men and Women after Oat Extract Consumption

Oat extract has been shown to modify blood glucose response and fasting lipids after dietary incorporation although some abdominal discomfort and increased flatulence were noted. To determine the extent of gas production, hydrogen and methane were determined after tolerance tests containing cooked and uncooked oat extract and after dietary incorporation. Breath gases were determined before and periodically after tolerance tests. Study 1: While consuming a maintenance diet, 24 subjects (55.3–112.5 kg body weight) underwent a tolerance test (1 g carbohydrate/kg body wt) of glucose (GTT, 1700 kJ/100 g) or uncooked, baked, or boiled pudding [2191 kJ/100 g carbohydrate, (0.67 glucose and 0.33 oat extract containing 10 g/100 g β-glucan)]. Hydrogen and methane expiration after all tolerance tests with the oat extract puddings, regardless of cooking method, was significantly higher than expirations after the GTT. Cooking the oat extract did not significantly change hydrogen or methane expiration. Study 2: Twenty-three subjects consumed a maintenance diet followed by the incorporation of oat extracts (50 g/8.33 MJ, 1 or 10 g/100 g β-glucan) to the diet in a crossover pattern. A GTT and a tolerance test containing 0.67 g glucose and 0.33 g of the respective oat extract/kg body weight were consumed after the maintenance and oat extract diet periods. Breath hydrogen was significantly higher after both oat extract tolerance tests than after the GTT. Hydrogen excretion after the 10% β-glucan oat extract was higher at 4, 5 and 6 h than after the 1% β-glucan oat extract; breath methane was not significantly different. These data indicate that cooking did not alter the influence of oat extracts on intestinal function, and increased β-glucan marginally increased hydrogen expiration. J. Nutr. 128: 79–84, 1998.

Effect of beta-glucan level in oat fiber extracts on blood lipids in men and women.

An active hypolipidemic component in oats, the soluble fiber beta-glucan, has been concentrated in an oat fiber extract. The oat fiber extract has been used to replace fat in food products. This study was designed to determine if moderate levels of oat fiber extract could be incorporated into a typical diet and whether plasma lipids could be reduced by the amount of beta-glucan added to the diet.Oat fiber extracts containing low (1% by weight) or high (10% by weight) beta-glucan were fed to 23 mildly hypercholesterolemic subjects (seven men and 16 women). A maintenance diet was fed for 1 week followed by diet containing an oat extract for 5 weeks each in a crossover pattern. Five percent of the energy from fat in the maintenance diet was replaced with the oat extract in the experimental diets. Caloric intake was adjusted to try to maintain each subject's initial weight. Fasting blood was collected several days apart after separate 12 hour fasts the end of each period. Plasma was analyzed for triglycerides, total cholesterol, and lipoprotein cholesterol fractions.HDL, HDL2, and VLDL cholesterol, and triglyceride levels after the oat extract diets were not significantly different from those after the maintenance diet. Total and LDL cholesterol levels decreased significantly (p < 0.001) from maintenance levels after both diets containing the oat extracts. Total cholesterol levels after the higher beta-glucan extract diet were significantly lower than those after the low beta-glucan diet.Beneficial reduction of cholesterol was obtained with modest amounts of oat extract incorporated into the diet. A significant dose response due to beta-glucan concentration in the oat extract was observed in total cholesterol levels.

Racial fertility differences: the role of female employment and education in wanted and unwanted childbearing.

This paper employs data from a merged sample of the National Surveys of Family Growth to examine how female employment status conditions the relationship between education and wanted and unwanted births among African American and white women. A rationale is presented for why a minority group status hypothesis that posits lower fertility among more highly educated African American women as compared to similar white women might find support in the case of wanted births and among certain women, including earlier birth cohorts. Our results provide some evidence for these ideas as well as evidence for a social characteristics hypothesis that predicts convergence of childbearing with rising education. However, persistently higher levels of unwanted births among African American women of all educational levels suggest that the dynamics of racial fertility differences are more complex than either of the hypotheses imply.