Showing papers by "University of Washington published in 1986"
TL;DR: In this paper, a tutorial on the Partial Least Squares (PLS) regression method is provided, and an algorithm for a predictive PLS and some practical hints for its use are given.
6,393 citations
TL;DR: In this paper, a set of new mathematical results on the theory of Gaussian random fields is presented, and the application of such calculations in cosmology to treat questions of structure formation from small-amplitude initial density fluctuations is addressed.
Abstract: A set of new mathematical results on the theory of Gaussian random fields is presented, and the application of such calculations in cosmology to treat questions of structure formation from small-amplitude initial density fluctuations is addressed. The point process equation is discussed, giving the general formula for the average number density of peaks. The problem of the proper conditional probability constraints appropriate to maxima are examined using a one-dimensional illustration. The average density of maxima of a general three-dimensional Gaussian field is calculated as a function of heights of the maxima, and the average density of 'upcrossing' points on density contour surfaces is computed. The number density of peaks subject to the constraint that the large-scale density field be fixed is determined and used to discuss the segregation of high peaks from the underlying mass distribution. The machinery to calculate n-point peak-peak correlation functions is determined, as are the shapes of the profiles about maxima.
3,098 citations
Book•
01 Jan 1986TL;DR: The book begins with a discussion of social interaction and observation and quickly moves into a classic study of interaction, Parten's (1932) study ofSocial interaction in children, which discusses recording methods but is notable for its lack of detail.
Abstract: odological concerns. This review is decidedly mixed. The book begins with a discussion of social interaction and observation and quickly moves into a classic study of interaction, Parten's (1932) study of social interaction in children. The issue of sequence versus marginal summation is brought in with argument favoring retention of sequence at all times until independence from sequence is established. Some discussion of the observation-theory issue in the philosophy of science is brought in (see Willson, 1987, for some commentary on this). The second chapter is devoted to developing a coding scheme for observation. It is here that the lack of attention to the reading literature is apparent. Frick and Semmel's (1978) paper is widely cited for development of coding schemes in reading. Researchers in this field have had to grapple with extremely complex issues. Flanders' (1960) work is often cited in education as an early effort, but does not appear in Bakeman and Gottman's book at all. Frick and Semmel pointed researchers to important considerations such as inference level in observation and its development in the coding scheme. This issue is not given nearly the space it requires, especially with the research showing the problems of reliability with highinference observation. The chapter ends with some examples of coding schemes but little practical advice on how to set up the coding schemes and the definitional menus that are absolutely required when several observers other than the developer are to use the system. Chapter 3 discusses recording methods but is notable for its lack of detail
2,409 citations
TL;DR: The biology of platelet derived growth factor, it will really give you the good idea to be successful.
1,999 citations
TL;DR: It is concluded that the combination of methotrexate and cyclosporine is superior to cyclOSporine alone in the prevention of acute graft versus host disease after marrow transplantation for leukemia, and that this therapy may have a beneficial effect on long-term survival.
Abstract: We treated 93 patients who had acute nonlymphoblastic leukemia in the first remission or chronic myelocytic leukemia in the chronic phase (median age, 30 years) with high-dose cyclophosphamide and fractionated total-body irradiation, followed by infusion of marrow from an HLA-identical sibling. To evaluate postgrafting prophylaxis for graft versus host disease, we studied these patients in a sequential, prospective, randomized trial that compared the effect of a combination of methotrexate and cyclosporine (n = 43) with that of cyclosporine alone (n = 50). All patients had evidence of sustained engraftment. A significant reduction in the cumulative incidence of grades II to IV acute graft versus host disease was observed in the patients who received both methotrexate and cyclosporine (33 percent), as compared with those who were given cyclosporine alone (54 percent) (P = 0.014). Seven patients who received cyclosporine alone acquired grade IV acute graft versus host disease, as compared with none who received both methotrexate and cyclosporine. Thirty-five of the 43 patients given both methotrexate and cyclosporine and 31 of the 50 patients given cyclosporine are alive as of this writing, at 4 months to 2 years (median, 15 months); the actuarial survival rates in the two groups at 1.5 years were 80 percent and 55 percent, respectively (P = 0.042). We conclude that the combination of methotrexate and cyclosporine is superior to cyclosporine alone in the prevention of acute graft versus host disease after marrow transplantation for leukemia, and that this therapy may have a beneficial effect on long-term survival.
1,373 citations
1,297 citations
TL;DR: In this paper, a multispectral image was modeled as mixtures of reflectance spectra of palagonite dust, gray andesitelike rock, and a coarse rock-like soil.
Abstract: A Viking Lander 1 image was modeled as mixtures of reflectance spectra of palagonite dust, gray andesitelike rock, and a coarse rocklike soil. The rocks are covered to varying degrees by dust but otherwise appear unweathered. Rocklike soil occurs as lag deposits in deflation zones around stones and on top of a drift and as a layer in a trench dug by the lander. This soil probably is derived from the rocks by wind abrasion and/or spallation. Dust is the major component of the soil and covers most of the surface. The dust is unrelated spectrally to the rock but is equivalent to the global-scale dust observed telescopically. A new method was developed to model a multispectral image as mixtures of end-member spectra and to compare image spectra directly with laboratory reference spectra. The method for the first time uses shade and secondary illumination effects as spectral end-members; thus the effects of topography and illumination on all scales can be isolated or removed. The image was calibrated absolutely from the laboratory spectra, in close agreement with direct calibrations. The method has broad applications to interpreting multispectral images, including satellite images.
1,118 citations
TL;DR: In this paper, the theory of a single charged particle in a Penning trap is reviewed, beginning with simple first-order orbits and progressively dealing with small corrections which must be considered owing to the experimental precision that is being achieved.
Abstract: A single charged particle in a Penning trap is a bound system that rivals the hydrogen atom in its simplicity and provides similar opportunities to calculate and measure physical quantities at very high precision. We review the theory of this bound system, beginning with the simple first-order orbits and progressively dealing with small corrections which must be considered owing to the experimental precision that is being achieved. Much of the discussion will also be useful for experiments with more particles in the trap, and several of the mathematical techniques have a wider applicability.
1,094 citations
TL;DR: It is shown that extremely simple adaptive load sharing policies, which collect very small amounts of system state information and which use this information in very simple ways, yield dramatic performance improvements.
Abstract: Rather than proposing a specific load sharing policy for implementation, the authors address the more fundamental question of the appropriate level of complexity for load sharing policies. It is shown that extremely simple adaptive load sharing policies, which collect very small amounts of system state information and which use this information in very simple ways, yield dramatic performance improvements. These policies in fact yield performance close to that expected from more complex policies whose viability is questionable. It is concluded that simple policies offer the greatest promise in practice, because of their combination of nearly optimal performance and inherent stability.
1,041 citations
TL;DR: Transfection of a full-length cDNA in mouse fibroblasts results in stable expression of NGF receptors that are recognized by monoclonal antibodies to the human NGF receptor and that bind [125I]NGF.
1,028 citations
TL;DR: This chapter examines relapse by integrating knowledge from the disorders of alcoholism, smoking, and obesity in an attempt to emphasize in a prototypical manner the overlap in etiological mechanisms and treatment rationales for disorders with powerful, underlying biological self-regulation components.
Abstract: This chapter examines relapse by integrating knowledge from the disorders of alcoholism, smoking, and obesity in an attempt to emphasize in a prototypical manner the overlap in etiological mechanisms and treatment rationales for disorders with powerful, underlying biological self-regulation components. Commonalities across these areas suggest at least three basic stages of behavior change: motivation and commitment, initial change, and maintenance. A distinction is made between the terms lapse and relapse, with lapse referring to the process (slips or mistakes) that may or may not lead to an outcome (relapse). The natural history of relapse is discussed, as are the consequences of relapse for patients and the professionals who treat them. Information on determinants and predictors of relapse is evaluated, with the emphasis on the interaction of individual, environmental, and physiological factors. Methods of preventing relapse are proposed and are targeted to the three stages of change. Specific research needs in these areas are discussed.
TL;DR: The panelists for the discussion were C. James Carrico, MD, from Seattle; Jonathan Meakins, DSc, FRCSC, FACS, from Montreal; Donald Fry,MD, from Cleveland; and Ronald V. Maier, MD from Seattle, who all had experience of multiple-organ-failure syndrome.
Abstract: INCIDENCE AND PROBLEMS OF MULTIPLE-ORGAN-FAILURE SYNDROMES The panelists for the discussion were C. James Carrico, MD, from Seattle; Jonathan Meakins, MD, DSc, FRCSC, FACS, from Montreal; Donald Fry, MD, from Cleveland; and Ronald V. Maier, MD, from Seattle. Dr Carrico: Multiple-organ-failure (MOF) syndrome is a process that occurs following 7% to 22% of emergency operations and between 30% and 50% of operations for intra-abdominal sepsis; MOF syndrome carries a mortality that varies from 30% to 100% depending on the number of organs involved. Treatment usually involves support of the organ (system) function and control of sepsis. 1,2 In developing a clinical description, we can use a classic description of respiratory failure from the late 1960s as a model. Rather than a single organ we need to describe the function of several systems and follow the changes through a series of stages, beginning with the patient who has recently experienced one
TL;DR: In this paper, it was shown that spin polarized determinants for an antiferromagnetic transition metal dimer and spin projected states obtained from them contribute to the Heisenberg coupling constant J describing a ladder of spin states.
TL;DR: In this paper, Lignin, elemental, and stable carbon isotope compositions are reported for local plants and for coarse (>63 µm) and fine (<63 mm) suspended particulate materials collected along a 1,950 km reach of the lower Amazon River during four contrasting stages of the 1982-1983 hydrograph.
Abstract: Lignin, elemental, and stable carbon isotope compositions are reported for local plants and for coarse (>63 µm) and fine (<63 µm) suspended particulate materials collected along a 1,950-km reach of the lower Amazon River during four contrasting stages of the 1982–1983 hydrograph. Fluxes of chemically recognizable lignin in the two size classes generally parallel each other along the mainstem with the fine fraction usually predominating. Particulate organic matter transported in the coarse size fraction of the mainstem and its major tributaries is composed of recently formed and well preserved tree leaf debris along with some wood. Organic matter in the fine size fraction is comparatively old, degraded, and rich in immobilized nitrogen and derives primarily from soils. C-4 grasses, which are abundant in the mainstem floodplain (varzea), are not major components of either the coarse or fine particulate material in the river.
Particulate organic matter in both size fractions is introduced largely from upstream sources within the Rio Solimoes and Rio Madeira drainage basins. Most of this organic matter is unreactive and is transported conservatively with mineral particles along the Amazon mainstem. However, some downstream compositional trends are seen in both size fractions which reflect the addition or exchange of highly degraded, 13C-depleted, and lignin-poor organic materials from lower basin sources.
TL;DR: CMV infection did not increase the risk of either acute or chronic GVHD, and the only risk factor for late excretion was CMV infection that occurred in the first 150 days after transplantation.
Abstract: The records of 545 patients were reviewed for risk factors associated with cytomegalovirus (CMV) infection after marrow transplant. CMV infection occurred among 36% of seronegative patients and 69% of seropositive patients. Among seronegative patients, significant risk factors for CMV infection included positive serology of the marrow donor (relative rate, 2.3) and the use of granulocyte transfusions from seropositive donors (relative rate, 2.5). Among both seronegative and seropositive patients, the occurrence of acute graft-versus-host disease (GVHD) significantly increased the risk of CMV infection (average relative rate, 1.8) and of subsequent CMV pneumonia (average relative rate, 2.6). CMV excretion and viremia were each associated with subsequent pneumonia, but the positive predictive values were low. One-third of long-term survivors excreted CMV at greater than 250 days after transplantation. The only risk factor for late excretion was CMV infection that occurred in the first 150 days after transplantation. In contrast to the effect of acute GVHD on CMV infection, CMV infection did not increase the risk of either acute or chronic GVHD.
TL;DR: The direct observation of quantum jumps between the 6-2 and 5-2 states is demonstrated, and the resulting ``telegraph signal'' provides a direct monitor of the atomic state.
Abstract: We demonstrate here the direct observation of quantum jumps between the ${6}^{2}$${\mathrm{S}}_{1/2}$ state and the ${5}^{2}$${\mathrm{D}}_{5/2}$ state of an individual laser-cooled ${\mathrm{Ba}}^{+}$ ions contained in a radio-frequency trap. The state detection and cooling are performed by two lasers which cause ${6}^{2}$${\mathrm{S}}_{1/2}$${\mathrm{\ensuremath{-}}6}^{2}$${\mathrm{P}}_{1/2}$${\mathrm{\ensuremath{-}}5}^{2}$ ${\mathrm{D}}_{3/2}$ transitions. Incoherent excitation to the ${5}^{2}$${\mathrm{D}}_{5/2}$ state (via the ${6}^{2}$${\mathrm{P}}_{3/2}$ level) causes the fluorescence from the ${6}^{2}$${\mathrm{P}}_{1/2}$ state to be suppressed for g30-sec lifetime of that state, after which the fluorescence reappears. The resulting ``telegraph signal'' provides a direct monitor of the atomic state.
TL;DR: In a special issue of R adiocarbon, Stuiver et al. as discussed by the authors presented a set of calibration curves for the age conversion of wood samples that were formed through use of atmospheric CO2.
Abstract: Calibration curves spanning several millennia are now available in this special issue of R adiocarbon. These curves, nearly all derived from the 14C age determinations of wood samples, are to be used for the age conversion of samples that were formed through use of atmospheric CO2. When samples are formed in reservoirs (eg, lakes and oceans) that differ in specific 14C content from the atmosphere, an age adjustment is needed because a conventional 14C age, although taking into account 14C (and 13C) fractionation, does not correct for the difference in specific 14C activity (Stuiver & Polach, 1977). The 14C ages of samples grown in these environments are too old, and a reservoir age correction has to be applied. This phenomenon has been referred to as the reservoir effect (Stuiver & Polach, 1977).
TL;DR: In this article, a transactional interpretation of quantum mechanics is presented, where quantum-mechanical wave functions are interpreted as real waves physically present in space rather than as "mathematical representations of knowledge".
Abstract: The interpretational problems of quantum mechanics are considered. The way in which the standard Copenhagen interpretation of quantum mechanics deals with these problems is reviewed. A new interpretation of the formalism of quantum mechanics, the transactional interpretation, is presented. The basic element of this interpretation is the transaction describing a quantum event as an exchange of advanced and retarded waves, as implied by the work of Wheeler and Feynman, Dirac, and others. The transactional interpretation is explicitly nonlocal and thereby consistent with recent tests of the Bell inequality, yet is relativistically invariant and fully causal. A detailed comparison of the transactional and Copenhagen interpretations is made in the context of well-known quantum-mechanical Gedankenexperimente and "paradoxes." The transactional interpretation permits quantum-mechanical wave functions to be interpreted as real waves physically present in space rather than as "mathematical representations of knowledge" as in the Copenhagen interpretation. The transactional interpretation is shown to provide insight into the complex character of the quantum-mechanical state vector and the mechanism associated with its "collapse." It also leads in a natural way to justification of the Heisenberg uncertainty principle and the Born probability law ($P=\ensuremath{\psi}{\ensuremath{\psi}}^{*}$), basic elements of the Copenhagen interpretation.
TL;DR: The magnitude of the potential performance difference between the various approaches indicates that the choice of coherence solution is very important in the design of an efficient shared-bus multiprocessor, since it may limit the number of processors in the system.
Abstract: Using simulation, we examine the efficiency of several distributed, hardware-based solutions to the cache coherence problem in shared-bus multiprocessors. For each of the approaches, the associated protocol is outlined. The simulation model is described, and results from that model are presented. The magnitude of the potential performance difference between the various approaches indicates that the choice of coherence solution is very important in the design of an efficient shared-bus multiprocessor, since it may limit the number of processors in the system.
TL;DR: The severity of hypokinesis at the site of acute myocardial infarction correlated better with infarct size estimated from creatine kinase release than did the ejection fraction or the circumferential extent of hypkinesis.
Abstract: We sought to identify theoretical advantages and applications of the centerline method for quantitative assessment of regional ventricular function. Motion was measured along 100 chords constructed perpendicular to a centerline drawn midway between the end-diastolic and end-systolic contours, and normalized for heart size. Abnormality was expressed in units of standard deviations from the mean motion in a normal reference population to indicate both the severity and significance of the wall motion abnormality. The mean abnormality averaged over 100 chords correlated highly with the area ejection fraction (r = .97). The centerline method uses a "sliding window" to measure motion where it is abnormal, because assessment of wall motion in predefined regions of the ventricular contour underestimates abnormality. From the 100 data points, the extent (% of contour) of regional abnormalities can also be determined. The severity of hypokinesis at the site of acute myocardial infarction correlated better with infarct size estimated from creatine kinase release (r = -.78) than did the ejection fraction or the circumferential extent of hypokinesis. Because the centerline method measures motion along locally determined vectors, and requires no apex, origin, coordinate system, or geometric reference figure, it can be applied to contours as dissimilar as the 60 degree left anterior oblique projection of the left ventricle and the 75 degree left anterior oblique projection of the right ventricle.
TL;DR: This initiation procedure provides another manner in which ethanol reinforcement can be instigated in animals that have not been either food- or fluid-deprived and is hypothesized that mechanisms which may regulate the intravascular and intragastric self-administration of ethanol may also be operating when the oral route is employed.
Abstract: Rats, maintained on free access to both food and water, were trained to press a lever to obtain a 20% sucrose solution. When presentation of the sucrose solution was maintaining responding, low ethanol concentrations were added to the solution. Over 25 sessions, the solution presented as reinforcement was gradually reduced in sucrose concentration until a 10% ethanol solution with no sucrose was presented. Following this initiation procedure, ethanol concentrations up to and including 40% ethanol were found to maintain responding. At the higher ethanol concentrations, the rats consumed doses of ethanol between 0.90 and 0.95 g/kg in the 30-min session. When a concurrent choice between ethanol and water was available in the operant chamber, the rats responded on the lever associated with 10% ethanol presentation. Home cage preference between ethanol and water was found to be altered following the operant ethanol experience with the rats acceptability for 10% ethanol increased prior to the start of the experiment This initiation procedure provides another manner in which ethanol reinforcement can be instigated in animals that have not been either food- or fluid-deprived. It is hypothesized that mechanisms which may regulate the intravascular and intragastric self-administration of ethanol may also be operating when the oral route is employed.
TL;DR: Measurements of foveola width and cone diameter reach the adult stage of development at 45 months of age, but the two important visual factors of outer segment length and cone packing density still are only half the adult values at 45 years of age.
TL;DR: In this article, a cognitive-affective model of stress and burnout is used to define the conditions under which withdrawal from a sport can be attributed to burnout, and its implications for preventing and coping with burnout are discussed.
Abstract: Although athletic burnout is a frequent topic of discussion and speculation, little in the way of a conceptual model or empirical data currently exists. An attempt is made to incorporate what is known about the nature, causes, and consequences of burnout within a cognitive-affective model of stress and to note the parallel situational, cognitive, physiologic, and behavioral components of stress and burnout. Thibaut and Kelley's social exchange model is used to define the conditions under which withdrawal from a sport can be attributed to burnout. Empirical findings concerning the causes and consequences of burnout derived from nonathletic populations are incorporated within the athletic burnout model, and its implications for preventing and coping with burnout are discussed. A number of conceptual and methodological issues are discussed, including operationalizing and measuring athletic burnout, the need for epidemiological research, and the assessment of causal and moderator variables. Based upon the lit...
TL;DR: In this article, the authors show that all of the statistical assumptions usually used in estimating transfer functions for geomagnetic induction data fail at periods from 5 min to several hours at Geomagnetic mid-latitudes.
Abstract: Summary. We show, through an examination of residuals, that all of the statistical assumptions usually used in estimating transfer functions for geomagnetic induction data fail at periods from 5 min to several hours at geomagnetic mid-latitudes. This failure can be traced to the finite spatial scale of many sources. In the past, workers have tried to deal with this problem by hand selecting data segments thought to be free of source effects. We propose an automatic robust analysis scheme which accounts for the systematic increase of errors with increasing power and which automatically downweights source contaminated outliers. We demonstrate that, in contrast to ordinary least squares, this automatic procedure consistently yields reliable transfer function estimates with realistic errors.
TL;DR: This chapter will focus primarily on skeletal muscle calcium channels, which have been investigated most thoroughly in skeletal muscle which has a particularly high density of calcium channels.
Abstract: Voltage sensitive calcium channels participate in action potential generation in electrically excitable cells and constitute an essential link between transient changes in membrane potential and a variety of cellular responses including secretion of neurotransmitters and hormones, initiation of contraction in cardiac and smooth muscle, and activation of second messenger responses in many cell types. Electrophysiological measurements have established the existence of multiple classes of calcium channels.1–4 Although work on many cell systems has contributed to current understanding of calcium channel function, the molecular properties of the channel have been investigated most thoroughly in skeletal muscle which has a particularly high density of calcium channels. This chapter will therefore focus primarily on skeletal muscle calcium channels.
TL;DR: Multivariate analysis showed disease status at time of transplantation to be the most powerful predictor of survival, and factors favoring survival were early transplantation, age less than 30 years, and absence of severe graft-versus-host disease.
Abstract: One hundred ninety-eight patients with chronic myelogenous leukemia received marrow transplants after intensive chemotherapy and total body irradiation. Multivariate analysis showed disease status at time of transplantation to be the most powerful predictor of survival. The probability of long-term survival for allogeneic graft recipients was 49% for 67 patients in the first chronic phase, 58% for 12 in the second chronic phase, 15% for 46 in the accelerated phase, and 14% for 42 in the blastic phase. The major cause of death was interstitial pneumonia for patients in the chronic phase, and relapse for those in the blastic or accelerated phases. Factors favoring survival were early transplantation, age less than 30 years, and absence of severe graft-versus-host disease. Splenectomy or spleen size did not influence survival. For recipients of syngeneic grafts survival probability was 87% for 16 patients in the chronic phase, 27% for 7 in the accelerated phase, and 12% for 8 in the blastic phase. Of the 198 patients, 71 are alive without Philadelphia chromosomes 1 to 9 years after receiving their graft. All but 4 long-term disease-free survivors have Karnofsky performance scores of 80% or better.
Patent•
25 Apr 1986TL;DR: In this paper, a thermal cautery system with an endoscopically deliverable probe connected to a power supply and display unit is described, where the current through the probe is sensed and used to increase the voltage at the output of the voltage regulator as the current increases to compensate for the voltage drop in the conductors connecting the probe to the power supply.
Abstract: A thermal cautery system having an endoscopically deliverable probe connected to a power supply and display unit. The power supply and display unit, when triggered by a footswitch, energizes a voltage regulator having a current limited output that supplies power to the probe. The current limiting function of the voltage regulator is disabled for a predetermined period that power is initially applied to said probe to minimize the heating time of said probe. The current through said probe is sensed and used to increase the voltage at the output of the voltage regulator as the current increases to compensate for the voltage drop in the conductors connecting the probe to the power supply. A manually selected portion of the sensed current through the probe is also integrated and used to terminate the flow of current through the probe when the integral of the current with respect to time has reached a predetermined value. A tone generator provides an audible indication when power is being applied to the probe and for a predetermined period thereafter to allow the probe to cool before the absence of the tone signals the removal of the probe from tissue being coagulated. The probe is heated by current flowing through an internal diode having a predetermined breakdown voltage at a predetermined temperature. The temperature of the probe is self-regulated by applying a voltage to the probe that is substantially equal to said predetermined voltage so that the current through the probe is reduced at said predetermined temperature.
TL;DR: Among mammals in general, there is no correlation between size of the testes and their location (abdominal or scrotal) in the body, or between size and body form and mode of locomotion (terrestrial, aquatic, aerial).
Abstract: We have assessed the allometric relationship between mass of testes and body mass using data from 133 mammalian species. The logarithmically transformed data were fitted by a regression ( r 2 = 0.86) that is described by the power function: Y = 0.035X0.72, where Y is mass of both testes in grams and X is body mass in grams. The slopes and intercepts of the allometric relationship for rodents alone (62 species) and primates alone (28 species) do not differ significantly from the relationship for the 133 species all taken together. Smaller mammals must allocate a greater proportion of body mass and of energy expenditure to testicular tissue than larger mammals; according to our allometric equation the testes of a 10 g mammal should comprise 1.8 percent of body mass, whereas testes of a 10,000 kg mammal amount to only 0.04 percent. Among the smallest mammals, the range of relative testes size is great; the testes of some rodents are as large as 8 percent of body mass, whereas others are as small as 0.15 percent. The energy cost for growth, maintenance, and production by mammalian testes is proportional to mass of testes and is, therefore, in most cases negligible. Among mammals in general we found no correlation between size of the testes and their location (abdominal or scrotal) in the body, or between size of testes and body form and mode of locomotion (terrestrial, aquatic, aerial). A functional relationship exists in many mammals between relative size of testes and mating system. Testes are relatively small in single-male breeding systems (monogamy or cases of extreme polygyny in which a single male does all the breeding). Testes are relatively large in multi-male breeding systems (promiscuous or polygynous systems where several different males mate with each female at the same estrus). In these cases, the evolution of large testes can be attributed to high copulatory frequency and sperm production and the competition among sperm of different males for fertilization of the same female. Size of testes has undoubtedly evolved in each species in response to a variety of additional factors beyond the first-order influence of body size. Tests of further hypotheses (for example, degree of seasonality of mating) that may explain the additional variability in size of testes should be performed. This should involve multivariate analyses of large data sets or simpler analyses that use data sets restricted to animals of similar body size, lower-level taxon, mating system, etc.