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Following total knee arthroplasties patients using the X10 increased their quadriceps strength 120% at 30 days post-surgery compared to their pre-surgical baseline. This contrasts sharply with contrast studies outpatient physical therapy that show patients suffer a 50-60% quadriceps strength deficit at 30 days post-surgery. For X10 patients, the average range of motion at 30 days was 124° and at discharge it was 128° (mean 43 days) . The trial involved a single surgeon and two groups. Group one (21 patients) used only the X10 for pre-habilitation and rehabilitation, while group two (20 patients) used X10 alone for pre-habilitation and then utilized the X10 plus home care plus outpatient physical therapy for rehabilitation. Adding home care and outpatient physical therapy did not improve outcomes compared to patients who utilized X10 alone. Our results show no significant difference between the two groups. Indicating that the X10 by itself is adequate to completely rehabilitation patients from total knee arthroplasties. Finally, we compared our results to those of Calatayud et al. 1 who monitored two groups of patients, one group had only physical therapy for rehabilitation while the other group used physical therapy for both prehabilitation and rehabilitation. Our results were superior to Calatayud et al. 1 for extension, flexion, and quadriceps strength; for each of these measures the X10 treatment groups improved over time, while the Calatayud et al. 1 groups showed losses., Competing Interests: Erin Rempher is employed by Halley Orthopedics the manufacturer of the X10 the operator of X10 Therapy. She has no stock in the company or financial conflicts. Daisy Ference, Robert Ference and D. Carl Freeman are not employed by Halley Orthopedics and have no financial interest in the company., (© 2021 Published by Elsevier B.V. on behalf of Professor P K Surendran Memorial Education Foundation.)

Background: We compared the effectiveness of liposomal bupivacaine to ropivacaine, each as part of multimodal pain management, in total knee arthroplasty (TKA) postoperative pain control., Methods: This prospective, double blind study randomized 96 TKA patients into a control group (periarticular injection of ropivacaine, ketorolac, morphine, and epinephrine in saline; 100cc) or an experimental group (periarticular injection of bupivacaine, ketorolac, morphine, and epinephrine in saline; 80cc plus 1.3% liposomal bupivacaine 20cc; total injection 100cc). The postoperative use of narcotics, visual analog pain scores, hours to ambulate 100 feet, and length of hospital stay were recorded., Results: There was no significant difference between the two groups (control N = 49, experiment N = 47) in mean narcotic use per hour, total narcotic use during hospital stay, time to ambulate 100 feet, length of hospital stay, or visual analog score for pain postoperatively., Conclusion: There is no benefit in the use of liposomal bupivacaine compared with ropivacaine for postoperative pain control in TKA., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Cellulite is a cosmetic condition of subcutaneous fat herniation through fibrous connective tissue that results in a dimpled appearance of the skin. Occurring in approximately 85% to 90% of all women worldwide, cellulite has been well studied. The result has been the development of a plethora of treatment protocols yielding little to no success. We describe a noninvasive mechanical treatment for women with cellulite, evaluating the safety and effectiveness of a technique that utilizes a unique patented device for the reduction of the visible appearance of cellulite.

Premise: The evolution of dioecy in plants is usually modeled as a consequence of self-fertilization. While increased seed and pollen production and dispersal patterns of specialized unisexuals have been examined, mating among relatives and interaction effects have been largely ignored. Here, we examine multiple variables simultaneously providing a more ecologically realistic set of conditions favoring the evolution of dioecy. •, Methods: We developed two complementary models to explore the evolution of dioecious plants. In both models, we examined the effects of inbreeding, compensation, and specialization on unisexual invasibility and were able to directly measure the influence of related matings on such a system. •, Key Results: Our results support previous studies indicating dispersal specialization, consanguineous mating, and inbreeding depression facilitate the evolution of dioecy. However, our results suggest that it is the interaction effect of multiple forces acting simultaneously that allows for unisexual invasion at thresholds and frequencies witnessed in nature. Additionally, our results suggest that subdioecious populations often result, and depending on population conditions, dioecy evolves at different rates, lending importance to the ecological and life history conditions of the species. •, Conclusion: Mating among relatives significantly enhances the invasibility of a unisexual mutant into a hermaphroditic population and lowers the levels of inbreeding depression required for invasion than previously reported conditions for unisexual invasion especially, if we consider multiple pressures simultaneously.

The growth and development of rice (Oryzae sativa) seedlings was shown to be regulated epigenetically by a fungal endophyte. In contrast to un-inoculated (nonsymbiotic) plants, endophyte colonized (symbiotic) plants preferentially allocated resources into root growth until root hairs were well established. During that time symbiotic roots expanded at five times the rate observed in nonsymbiotic plants. Endophytes also influenced sexual reproduction of mature big sagebrush (Artemisia tridentata) plants. Two spatially distinct big sagebrush subspecies and their hybrids were symbiotic with unique fungal endophytes, despite being separated by only 380 m distance and 60 m elevation. A double reciprocal transplant experiment of parental and hybrid plants, and soils across the hybrid zone showed that fungal endophytes interact with the soils and different plant genotypes to confer enhanced plant reproduction in soil native to the endophyte and reduced reproduction in soil alien to the endophyte. Moreover, the most prevalent endophyte of the hybrid zone reduced the fitness of both parental subspecies. Because these endophytes are passed to the next generation of plants on seed coats, this interaction provides a selective advantage, habitat specificity, and the means of restricting gene flow, thereby making the hybrid zone stable, narrow and potentially leading to speciation.

The life span of model organisms can be modulated by environmental conditions that influence cellular metabolism, oxidation, or DNA integrity. The yeast nicotinamidase gene pnc1 was identified as a key transcriptional target and mediator of calorie restriction and stress-induced life span extension. PNC1 is thought to exert its effect on yeast life span by modulating cellular nicotinamide and NAD levels, resulting in increased activity of Sir2 family class III histone deacetylases. In Caenorhabditis elegans, knockdown of a pnc1 homolog was shown recently to shorten the worm life span, whereas its overexpression increased survival under conditions of oxidative stress. The function and regulation of nicotinamidases in higher organisms has not been determined. Here, we report the identification and biochemical characterization of the Drosophila nicotinamidase, D-NAAM, and demonstrate that its overexpression significantly increases median and maximal fly life span. The life span extension was reversed in Sir2 mutant flies, suggesting Sir2 dependence. Testing for physiological effectors of D-NAAM in Drosophila S2 cells, we identified oxidative stress as a primary regulator, both at the transcription level and protein activity. In contrast to the yeast model, stress factors such as high osmolarity and heat shock, calorie restriction, or inhibitors of TOR and phosphatidylinositol 3-kinase pathways do not appear to regulate D-NAAM in S2 cells. Interestingly, the expression of D-NAAM in human neuronal cells conferred protection from oxidative stress-induced cell death in a sirtuin-dependent manner. Together, our findings establish a life span extending the ability of nicotinamidase in flies and offer a role for nicotinamide-modulating genes in oxidative stress regulated pathways influencing longevity and neuronal cell survival.

Proximal row carpectomy with capitate head resection and dorsal capsular interposition was performed in 8 patients with stage II and III scapholunate advanced collapse (SLAC). Mean patient age was 58.5 years (range, 50-79 years). One year postoperatively, range of motion and grip strength were not significantly changed from preoperative values. Mean postoperative Disabilities of the Arm, Shoulder, and Hand questionnaire score was 27. Pain improved from 8.8 preoperatively to 4.3 postoperatively on a scale of 0-10. Pain levels were highly inversely correlated with final range of motion (r=-0.94, P=.0004). Proximal row carpectomy with capitate leveling and capsular interposition for stage II and III SLAC wrist provides reasonable pain relief in 75% of patients. Patients should be counseled that 25% of cases may demonstrate progression of radiocapitate degeneration, necessitating further intervention.

When addressing the nature of ecological adaptation and environmental factors limiting population ranges and contributing to speciation, it is important to consider not only the plant's genotype and its response to the environment, but also any close interactions that it has with other organisms, specifically, symbiotic microorganisms. To investigate this, soils and seedlings were reciprocally transplanted into common gardens of the big sagebrush hybrid zone in Salt Creek Canyon, Utah, to determine location and edaphic effects on the fitness of parental and hybrid plants. Endophytic symbionts and functional microbial diversity of indigenous and transplanted soils and sagebrush plants were also examined. Strong selection occurred against the parental genotypes in the middle hybrid zone garden in middle hybrid zone soil; F(1) hybrids had the highest fitness under these conditions. Neither of the parental genotypes had superior fitness in their indigenous soils and habitats; rather F(1) hybrids with the nonindigenous maternal parent were superiorly fit. Significant garden-by-soil type interactions indicate adaptation of both plant and soil microorganisms to their indigenous soils and habitats, most notably in the middle hybrid zone garden in middle hybrid zone soil. Contrasting performances of F(1) hybrids suggest asymmetrical gene flow with mountain, rather than basin, big sagebrush acting as the maternal parent. We showed that the microbial community impacted the performance of parental and hybrid plants in different soils, likely limiting the ranges of the different genotypes.

Purpose: To report our experience using a fixed-angle volar plate in conjunction with a corrective osteotomy and cancellous bone graft for the treatment of distal radius malunions with dorsal angulation in 4 patients., Methods: Four consecutive patients had a volarly based opening wedge osteotomy with a fixed angle volar plate and cancellous bone grafting for the treatment of a dorsally angulated distal radius malunion. Data collected retrospectively included a visual analog pain scale, grip strength, range of motion, radiographic parameters, and each patient's subjective functional outcomes as measured by the Disabilities of the Arm, Shoulder, and Hand questionnaire. Motion, strength, and radiographic values were compared with the contralateral arm for each patient., Results: The average time from initial fracture to corrective osteotomy was 346 days. The average length of follow-up evaluation was 13.5 months. The flexion-extension arc of motion increased an average of 21 degrees to a value of 84% of the contralateral side; the pronation-supination arc of motion increased an average of 20 degrees to a value of 98% of the contralateral side. The average tilt of the radius improved from 26 degrees extension to 2 degrees extension; the average radial inclination improved from 22 degrees to 24 degrees; the average ulnar variance excluding the 1 patient who had a distal ulna resection improved from 5 mm to 1 mm. The average retrospective Disabilities of the Arm, Shoulder, and Hand score improved from 30 to 7; the average retrospective visual analog pain scale score improved from 4.5 to 1. The average grip strength increased from 20 to 29 kg, which corresponded to 73% of the contralateral extremity., Conclusions: The rigid characteristics of fixed angle volar plates can provide an alternative to the traditional techniques of distal radius osteotomy including structural bone grafting and dorsal plate fixation or external fixation. In addition these plates are strong enough to allow for early postoperative motion., Type of Study/level of Evidence: Therapeutic, Level IV.

Chromosome translocations are used to estimate the doses of radiation received following occupational or accidental exposure. Biodosimetry relies on the assumption that translocations are not cell-lethal and persist with little or no loss over time. While translocations do exhibit substantially greater persistence than other aberration types (e.g., dicentrics), there is evidence that translocation frequencies also decline over time, at least following acute doses above 1 Gy. To the extent that translocation frequencies decline, the predicted absorbed doses will be underestimated. Yet unknown is whether translocations induced by ionizing radiation at doses below 1 Gy also show significant declines. Here we report on the persistence of translocations induced by 137Cs gamma-rays at acute doses ranging from 0.2 to 4 Gy using peripheral blood lymphocytes from two unrelated healthy male donors. Chromosome aberrations were evaluated by simultaneously painting chromosomes 1, 2, and 4 in red and 3, 5, and 6 in green in cells harvested 2-7 days following exposure and were scored using the PAINT system. Translocations were also enumerated using several other methods and these results are reported separately by us in this issue. For comparison, the persistence of dicentrics, rings, acentric fragments, and color junctions was also evaluated and showed rapid losses with time. The results from both donors provide evidence that translocation frequencies decline with time in a statistically significant manner at doses as low as 0.2-0.3 Gy. The frequency of translocations for all dose groups declined from day 2 to 7 by averages of 39% and 26% for donors 1 and 2, respectively. These data emphasize the importance of considering translocation loss in biological dosimetry long times after exposure.

Chromosome breaks and rearrangements resulting from ionizing radiation can be much more complicated than many investigators thought possible some years ago. The realization that not all translocations are reciprocal, that multiway exchanges occur, and that some double-strand breaks are not repaired prior to mitosis have all contributed to the difficulty of knowing how best to identify, record, evaluate, and report chromosome translocations. Here we describe the results of a series of experiments in which blood from two normal healthy subjects was obtained, irradiated with 137Cs gamma-rays in vitro at doses ranging from 0 (controls) to 4 Gy, and cultured. Cells from each dose group and donor were harvested at days 2, 2.5, 3, 4, 5, and 7 and evaluated for chromosome damage by simultaneously painting chromosomes 1, 2, and 4 in red and 3, 5, and 6 in green. The persistence of dicentrics, fragments, rings, insertions, and PAINT translocations are reported separately by us in this issue. In this article, we focus on translocations, characterizing the various types in detail and comparing and contrasting their persistence across all dose groups for both donors. The results indicate that the persistence of all translocation types was sufficient to be used for retrospective dosimetry, although nonreciprocal translocations exhibited diminished persistence compared to the other types. We also characterize the kinetics of the radiation dose responses of the two donors who exhibited significant differences in the induction as well as the persistence of translocations. Based on the evidence presented here, we hypothesize that these individuals differ in the recognition and repair of radiation-induced damage as well as in cell cycle checkpoint control. Despite these differences, the temporal frequency of translocation losses at both the high and low doses was similar for both subjects.

Background: Several shoulder function scores are used in research, with no universally adopted standard. This study compares 6 shoulder outcome scales., Hypothesis: Correlations exist between shoulder outcome scales, allowing conversion between scales. Shoulder scales are correlated with age., Study Design: Regression and correlation study., Methods: Seventy subjects with shoulder pain completed 6 shoulder outcome scales. Pearson correlations were calculated between the total scores of the 6 instruments, between the components of the scales, and with age. Regression equations were calculated between scales., Results: The range of r values for total scores was 0.495 < or = r < or = 0.770, P < or = .01. In general, a scale's components were themselves highly correlated and added little new information to the scale (0.260 < or = r < or = 0.705, P < or = .05). Most of the scale scores were highly correlated with age (0.291 < or = r < or = 0.582, P < or = .05). Constant's reported corrections for age reduced (from r = -0.582 to r = -0.250, P < .05) but did not eliminate age as a confounding variable., Conclusions: Correlations exist between shoulder outcome scales, but existing shoulder scales are not equivalent in their assessments of function; they contain redundant information and, in some cases, may reflect a patient's age better than his/her shoulder function. The utility of conversion equations is minimized as a result of low to moderate correlations between scales., (Copyright 2004 American Orthopaedic Society for Sports Medicine)

Introduction: Shoulder strength is an integral component of shoulder function. In assessing shoulder function many functional scales rely on direct or indirect measures of strength. Strength, and thus these scales, is often highly correlated with age. We propose an allometric method for assessing shoulder strength. Allometric modeling has provided accurate predictions of biologic growth and physiologic function in both human and animal studies. Allometry utilizes the relationship between the two homologous structures on the left and right sides of the body, providing in effect an internal control and thus eliminating many confounding effects, e.g. age and level of activity., Methods: Twenty patients with unilateral shoulder dysfunction underwent strength testing of their affected and unaffected shoulder. Strength testing of the bilateral shoulders was also assessed in twenty people without shoulder pain in order to delineate the effect of hand dominance on strength in those without shoulder pain. Absolute and predicted strength deficits of the involved shoulder were calculated via regression analysis. Pearson's correlation coefficients were computed between age and strength., Results: Utilizing the contralateral extremity as an internal control eliminates age as a confounding variable in predicting strength outcomes (r = 0.093)., Conclusion: Allometric concepts, applied to shoulder strength assessment, eliminates age as a confounding variable. Strength testing of both shoulders should be considered in the development of future shoulder outcome scales in order to eliminate the strong influence of age.

We examined habitat disturbance, species richness, equitability, and abundance of ants in the Fall-Line Sandhills, at Fort Benning, Georgia. We collected ants with pitfall traps, sweep nets, and by searching tree trunks. Disturbed areas were used for military training; tracked and wheeled vehicles damaged vegetation and soils. Highly disturbed sites had fewer trees, diminished ground cover, warmer soils in the summer, and more compacted soils with a shallower A-horizon. We collected 48 species of ants, in 23 genera (141,468 individuals), over four years of sampling. Highly disturbed areas had fewer species, and greater numbers of ants than did moderately or lightly disturbed areas. The ant communities in disturbed areas were also less equitable, and were dominated by Dorymyrmex smithi.

Several species of gall-forming insects specialize on big sagebrush (Artemisia tridentata), a species that shows much clinal and subspecific variation throughout its geographic range. Two of those subspecies, basin big sagebrush (A. t. ssp. tridentata) and mountain big sagebrush (A. t. ssp. vaseyana), form a narrow hybrid zone at Salt Creek, Utah. Reciprocal transplant experiments have shown that the hybrid big sagebrush at Salt Creek are more fit than either parental subspecies, but only in the hybrid zone. Do genotype and environment influence the density and distribution of galls on big sagebrush? We counted galls on parental and hybrid big sagebrush in three reciprocal transplant gardens at Salt Creek. Gardens were in each of the two parental zones and in the hybrid zone. Transplanted seedlings came from five source populations: two parental and three hybrid populations. We identified seven kinds of gall-forming flies (Rhopalomyia midges and Eutreta fruitflies) that produced identifiable galls. Densities of galls varied among the three gardens and five source populations, and there was also a significant garden by source interaction in gall density. In general, variation in gall density among gardens (i.e., environments) was much greater than the variation among source populations (i.e., genotypes). Nevertheless, significant genotype-environment interactions were observed for five of the seven kinds of galls. Overall density of galls, mostly due to Rhopalomyia ampullaria, was greatest in the high-elevation (mountain) garden and least in the low-elevation (basin) garden. To the best of our knowledge, this is the first reciprocal transplant experiment addressing herbivore richness in a hybrid zone.

We examined components of male and female reproductive success in protogynous and protandrous sexual morphs of the heterodichogamous and largely monoecious chenopod shrub Grayia brandegei. Percentage femaleness of flowering stalks ranged from 0 to 37.6% female ( = 15.5%) for protandrous plants and from 14 to 100% female ( = 55.8%) for protogynous plants. Functional gender estimates based on ovule production at two locations ranged from 23.0 to 31.8% female for the protandrous morph, and from 65.3 to 77.0% female for the protogynous morph. Realized gender estimates based on total seed production ranged in value from 3.6 to 16.8% female for the protandrous morph and from 76.5 to 96.4% for the protogynous morph, depending on location and year. Differences in reproductive success of the two morphs were largely due to a reduction in the female function of protandrous plants. Protogynous plants produced more female flowers per stalk and had a higher percentage of seed-filled fruits than did protandrous plants. Differences between sexual morphs were more pronounced in dry areas or years in which overall seed production was minimal. Differential seed production between morphs likely reflects temporal patchiness in environmental conditions, particularly in water availability. The significance of these findings in support of heterodichogamy as an evolutionary pathway to dioecy is discussed.

Developmental instability is often assessed using deviations from perfect bilateral symmetry. Here, we review the literature describing previous studies, suggest mechanisms that may account for both the generation and disruption of bilateral symmetry, and examine the influence of electromagnetic fields on the asymmetry of soybean leaves. Leaves from plants under high-voltage power lines generating pulsed magnetic fields of <3 to >50 mG were more asymmetrical for two parameters (the terminal leaflet widths and lateral rachilla lengths) than leaves of plants even 50 or 100 m away from power lines. This asymmetry could not be attributed to either size scaling or measurement error.

The comparison between complexity in the sense of space occupancy (box-counting fractal dimension Dc and information dimension DI) and heterogeneity in the sense of space distribution (average evenness index J&d1; and evenness variation coefficient JCV) were investigated in mathematical fractal objects and natural branch structures. In general, increased fractal dimension was paired with low heterogeneity. Comparisons between branch architecture in Anthyllis cytisoides under different slope exposure and grazing impact revealed that branches were more complex and more homogeneously distributed for plants on northern exposures than southern, while grazing had no impact during a wet year. Developmental instability was also investigated by the statistical noise of the allometric relation between internode length and node order. In conclusion, our study demonstrated that fractal dimension of branch structure can be used to analyze the structural organization of plants, especially if we consider not only fractal dimension but also shoot distribution within the canopy (lacunarity). These indexes together with developmental instability analyses are good indicators of growth responses to the environment.

The concentrations of selected elements and their biological absorption coefficients were determined for leaves from plants in native stands and reciprocal transplant gardens to determine whether niche differentiation occurs among the parental taxa and their hybrids in the big sagebrush hybrid zone in Utah. The bounded hybrid superiority model predicts such niche differentiation, while the ecologically neutral dynamic equilibrium model predicts complete niche overlap, at least in the vicinity of the hybrid zone. The concentrations of elements in the leaves of site-indigenous sagebrush and the biological absorption coefficients differed significantly between the subspecies and between either parental taxon and hybrids. Within reciprocal transplant gardens, both the elemental concentrations and the biological absorption coefficients differed among the gardens and taxa. Significant genotype-by-environment interactions were observed for several essential elements. Niche differentiation was evident as correspondence analyses ordinated the parental taxa and hybrids into separate groups even when raised in the same garden. These findings support the ecologically based bounded hybrid superiority model and suggest that the big sagebrush parental taxa and their hybrids have adapted to their respective unique habitats.

Long term effects of glenohumeral joint translational (gliding) manipulation on range of motion, pain, and function in patients with adhesive capsulitis were studied. Thirty-one patients underwent brachial plexus block followed by translational manipulation of the glenohumeral joint. Changes in range of motion and pain were assessed before manipulation with the patient under anesthesia, immediately after manipulation with the patient still under anesthesia, at early followup (5.3 +/- 3.2 weeks), and at long term followup (14.4 +/- 7.3 months). Passive range of motion increased significantly for flexion, abduction, external rotation, and internal rotation. Significant decreases in visual analog pain scores between initial evaluation and the followup assessments also occurred. Furthermore, Wolfgang's criteria score increased significantly between initial evaluation and followup assessments. Translational manipulation provides a safe, effective treatment option for adhesive capsulitis.

Neo-Darwinian theory is highly successful at explaining the emergence of adaptive traits over successive generations. However, there are reasons to doubt its efficacy in explaining the observed, impressively detailed adaptive responses of organisms to day-to-day changes in their surroundings. Also, the theory lacks a clear mechanism to account for both plasticity and canalization. In effect, there is a growing sentiment that the neo-Darwinian paradigm is incomplete, that something more than genetic structure, mutation, genetic drift, and the action of natural selection is required to explain organismal behavior. In this paper we extend the view of organisms as complex self-organizing entities by arguing that basic physical laws, coupled with the acquisitive nature of organisms, makes adaptation all but tautological. That is, much adaptation is an unavoidable emergent property of organisms' complexity and, to some a significant degree, occurs quite independently of genomic changes wrought by natural selection. For reasons that will become obvious, we refer to this assertion as the attractor hypothesis. The arguments also clarify the concept of "adaptation." Adaptation across generations, by natural selection, equates to the (game theoretic) maximization of fitness (the success with which one individual produces more individuals), while self-organizing based adaptation, within generations, equates to energetic efficiency and the matching of intake and biosynthesis to need. Finally, we discuss implications of the attractor hypothesis for a wide variety of genetical and physiological phenomena, including genetic architecture, directed mutation, genetic imprinting, paramutation, hormesis, plasticity, optimality theory, genotype-phenotype linkage and puncuated equilibrium, and present suggestions for tests of the hypothesis. (c) 1998 American Institute of Physics.

Does endogenous or exogenous selection stabilize the big sagebrush (Artemisia tridentata) hybrid zone? After two years of study, our reciprocal transplant experiments showed significant genotype by environment interactions for a number of fitness components, including germination, growth, and reproduction. Hybrids were the most fit within the hybrid garden. In the parental gardens, the native parental taxon was more fit than either the alien parental or hybrids. These results are consistent with the bounded hybrid superiority model, which assumes exogenous selection, but are clearly at odds with the dynamic equilibrium model, which assumes endogenous selection and universal hybrid unfitness., (© 1997 The Society for the Study of Evolution.)

The squirrel monkey lacks anatomically demonstrable ocular dominance columns, and physiologically it has an ocular dominance distribution in V1 that is very different from that of macaques, with far fewer cells that strongly favor one eye over the other. We tested an alert squirrel monkey for physiological responses to stereoscopic stimuli by measuring evoked potentials in response to cytclopean patterns generated in dynamic random-dot stereograms. The monkey showed evoked responses both to changes in disparity and to shifts between correlation and uncorrelation between the two eyes. This result strongly suggests that the squirrel monkey can detect stereoscopic depth, which in turn casts some doubt on the assumption that ocular dominance columns bear an important relation to stereopsis.

: Developmental stability refers to the ability of a developing organism to produce a consistent phenotype in a given environment. It provides a simple, reliable method of detecting stressed populations and monitoring their recovery. The most common measure of developmental instability, fluctuating asymmetry, assesses minor deviations from perfect bilateral symmetry in traits that are normally symmetrical. Measures of developmental instability are based upon the concept of developmental invariance. The biotest approach consists of the simultaneous analysis of developmental instability (and related physiological instability) in a variety of species.

The influence of environmental heterogeneity on components of male and female fitness is examined using Atriplex canescens growing on steep slopes and alluvium at the slope base as a model system. Female fitness is estimated as the grams of fruit produced per plant and the grams of fruit per gram leaf tissue. Male fitness is estimated as the grams of stamens produced, the number of pollen grains dispersed to a given distance, and the potential number of grams of fruit sired taking into consideration the number and distribution of mates and competing pollen donors. The influence of increased plant size on male and female fitness components, the cost of reproduction (as measured by biomass, joules and nitrogen) on a gross level and a per offspring basis are also examined. The results indicate that the female function is more limited on the slope than the male function. The efficiency of pollen dispersal (the number of pollen grains per unit donor plant volume dispersed to a given distance) is enhanced by growing on slopes. Males become less efficient at dispersing pollen as they increase in size, while the efficiency of female reproduction (grams of fruit per volume or gram leaf tissue) is unaffected by increasing plant size. The cost to a male of siring a gram of fruit is about the same as the cost to a female of producing the gram of fruit. Implications for the evolution of sexual lability and dioecy are discussed.

Prior studies have alternatively considered floral phenotypes in Atriplex canescens as trioecious (having three sexual genders) and/or dioecious and having a "leaky genetical switch." Clones transplanted from three populations and grown in common gardens reveal the existence of two distinctly different genetic controls regulating gender expression. In some clones gender is fixed as male (staminate) or female (pistillate), while in other clones gender varies, ranging from a mixture of male and female ramets to simultaneous hermaphrodites with various proportions of male and female flowers. For clones which vary their sex expression, variation occurs within irrigation treatments, between treatments and over time, as a consequence of the combined effects of genotype plus environment. The magnitude of sex change is also a product of the interaction of genetics and environment. Some clones have been repeatedly examined for 20 years., (© 1992 The Society for the Study of Evolution.)

The distribution of male and female plants was examined in five dioecious, wind-pollinated species representing five plant families and two classes (gymnosperms and angiosperms). The arid to semiarid habitats occupied by these species in northern Utah were stratified for sampling into two categories: chronically xeric and seasonally moist. The results show that for all species, males are more abundant on xeric microsites, while females are over represented on the moister parts of each local environment. Differential distribution of the sexes along a soil moisture gradient is a strategy that maximizes seed set of females and pollen dispersal of males; it also tends to minimize intraspecific competition between the sexes.

The Eyring-Stover theory of survival developed in earlier papers can be readily applied to a wide diversity of ecological phenomena, with implications for identifying basic responses of organisms to their environment. We report several examples to demonstrate the generality of the theory.

Evidence is presented that individuals of a large number of dioecious and subdioecious plant species are able to alter their sexual state in response to changes in the ambient environment and/or changes in size or age. We suggest that lability of sexual expression probably has survival value where a significant portion of the females must otherwise bear the cost of fruit production in unfavorable environments. We demonstrate that in patchy environments of the proper scale and variability in quality, labile sexual expression will enhance an individual's genetic contribution to the next generation.