Showing papers by "University of Maine published in 1996"

Forensic Taphonomy : The Postmortem Fate of Human Remains

Abstract: Foreword, J.H. Davis Preface, G. Haynes INTRODUCTION: INTRODUCTION TO FORENSIC TAPHONOMY, W.D. HAGLUND AND M.H. SORG Taphonomy in the Forensic Context Method and Theory of Taphonomic Research, W.D. Haglund and M.H. Sorg Context Delicti: Archaeological Context in Forensic Work, D.D. Scott and M. Connor The Role of Archaeology in the Recovery and Interpretation of Human Remains from an Outdoor Forensic Setting, D.C. Dirkmaat and J.M. Adavasio Chain of Custody from the Field to the Courtroom, J. Melbye and S.B. Jimenez Taphonomic Applications in Forensic Anthropology, D.H. Ubelaker MODIFICATIONS OF SOFT TISSUE, BONE, AND ASSOCIATED MATERIALS: OVERVIEW, W.D. HAGLUND AND M.H. SORG Chemical Underpinnings Chemical and Ultrastructural Aspects of Decomposition, H. Gill-King Preservation and Recovery of DNA in Postmortem Specimens and Trace Samples, T.J. Parsons and V.W. Weedn Soft Tissue The Process of Decomposition: A Model from the Arizona-Sonoran Desert, A. Galloway Postmortem Changes in Soft Tissue, M.A. Clark, M.B. Worrell, and J.E. Pless Recognition of Cemetery Remains in the Forensic Setting, H.E. Berryman, W.M. Bass, S.A. Symes, and O.T. Smith Frozen Environments and Soft Tissue Preservation, M.S. Micozzi Outdoor Decomposition Rates in Tennessee, W.M. Bass, III Bone Microscopic Structure of Bone, M. Schultz Microscopic Investigation of Excavated Skeletal Remains: A Contribution to Paleopathology and Forensic Medicine, M. Schultz A Critical Evaluation of Bone Weathering as an Indication of Bone Assemblage Formation, L.R. Lyman and G.L. Fox Eskimo Skeleton Taphonomy with Identification of Possible Polar Bear Victims, C.F. Merbs Human Variables in the Postmortem Alteration of Human Bone: Examples from U.S. War Casualties, T.D. Holland, B.E. Anderson, and R.W. Mann Fire Modification of Bone: A Review of the Literature, P.M. Mayne Correia Human Bone Mineral Densities and Survival of Bone Elements: A Contemporary Sample, A. Galloway, P. Willey, and L. Snyder Cranial Bone Displacement as a Taphonomic Process in Potential Child Abuse Cases, T.A.J. Crist, A. Washburn, H. Park, I. Hood, and M.A. Hickey Associated Materials Biodegradation of Hair and Fibers, W.F. Rowe Forensic Botany, D. Hall SCAVENGED REMAINS: OVERVIEW, W.D. HAGLUND AND M.H. SORG Carnivore Scavenged Remains Dogs and Coyotes: Postmortem Involvement with Human Remains, W.D. Haglund Scattered Skeletal Remains: Search Strategy Considerations for Locating Missing Teeth, W.D. Haglund The Utilization of Faunal Evidence in the Recovery of Human Remains, T.A. Murad Rodent Scavenged Remains Rodents and Human Remains, W.D. Haglund Scavenging by Insects On the Body: Insects' Life Stage Presence, Their Postmortem Artifacts, and Entomological Collecting Procedures, N.H. Haskell, V.J. Cervenka, and M.A. Clark Scavenging by Water Organisms Human Remains Recovered from a Shark's Stomach in South Carolina, T.A. Rathbun and B.C. Rathbun BURIED AND PROTECTED REMAINS: OVERVIEW, W.D. HAGLUND AND M.H. SORG Decomposition Decomposition of Buried and Submerged Bodies, W.C. Rodriguez III Decomposition Rates of Deliberate Burials: A Case Study of Preservation, M.H. Manheim Autopsied, Embalmed, and Preserved Human Remains: Distinguishing Features in Forensic and Historic Contexts, P.S. Sledzik and M.S. Micozzi Necrosearch Revisited: Further Multidisciplinary Approaches to the Detection of Clandestine Graves, D.L. France, T.J. Griffin, J.G. Swanburg, J.W. Lindemann, G.C. Davenport, V. Trammell, C.T. Travis, B. Kondratieff, A. Nelson, K. Castellano, D. Hopkins, and T. Adair Preservation in Late 19th Century Iron Coffin Burials, D.W. Owsley and B.E. Compton REMAINS IN WATER: OVERVIEW, W.D. HAGLUND AND M.H. SORG Riverine Environments Fluvial Transport of Human Crania, S.P. Nawrocki, J.E. Pless, D.A. Hawley, and S.A. Wagner The Taphonomic Effects of Flood Waters on Bone, S. Brooks and R.H. Brooks Lacustrine Environments Movement of Bodies in Lake Ontario, Tyler G. O'Brien Marine Environments Forensic Taphonomy in Marine Contexts, M.H. Sorg, J.H. Dearborn, E.I. Monahan, H.F. Ryan, K.G. Sweeney, and E. David Human Aquatic Taphonomy in the Monterey Bay Area, S. Boyle, A. Galloway, and R.T. Mason Burials at Sea, M.R. London, J.F. Krolikowski, and J.H. Davis CONCLUSIONS AND OVERVIEW, W.D. HAGLUND AND M.H. SORG Afterword, C.C. Snow

Display Rules for Anger, Sadness, and Pain: It Depends on Who Is Watching

Abstract: This study examined factors that may influence children's decisions to control or express their emotions including type of emotion (anger, sadness, physical pain), type of audience (mother, father, peer, alone), age, and sex. Children's reported use of display rules, reasons for their decisions, and reported method of expression were examined. Subjects were 32 boys and 32 girls in each of the first (M = 7.25 years old), third (M = 9.33 years old), and fifth grades (M = 11.75 years old). Regardless of the type of emotion experienced, children reported controlling their expression of emotion significantly more in the presence of peers than when they were with either their mother or father or when they were alone. Younger children reported expressing sadness and anger significantly more often than did older children, and girls were more likely than boys to report expressing sadness and pain. Children's primary reason for controlling their emotional expressions was the expectation of a negative interpersonal interaction following disclosure.

Stress tolerance in intertidal seaweeds

Abstract: Intertidal seaweeds are periodically exposed to air where they experience a variety of potentially stressful environmental conditions, including nutrient limitation, high light, high and low temperature, desiccation, and osmotic stress. This paper considers the current understanding of stress tolerance in intertidal seaweeds and discusses ways in which future research could increase our understanding of the role of environmental factors in the ecology and physiology of these algae. We believe research is required in at least three areas. 1) Laboratory physiological studies have established that correlations exist between stress tolerance and the vertical distribution of species. However, little information is available on the importance of stress in determining community structure in nature. Field experiments are essential to relate the impact of single or multiple stresses on the survival, growth, and reproductive output of macroalgae. In paticular, it is necessary to clarify the role of sublethal stress in determining the outcome of competitive interactions. 2) With the exception of obvious lethal effects or damage associated with extreme environmental conditions, such as unusually hot and dry weather, it is difficult to evaluate the occurrence and severity of stress in natural populations of seaweeds. There is a need to develop molecular and biochemical markers specific for individual stresses or groups of stresses to allow the unambiguous and direct determination of stress in situ. 3) Despite the apparent importance of stress in intertidal seaweeds, we are largely ignorant of the mechanistic basis of tolerance. The application of currently available tools of molecular and cell biology to the investigation of stress-induced transcriptional and translational changes could enormously increase our understanding of both the sites of, and pathways involved in, stress tolerance. In summary, there are numerous unanswered fundamental questions about the stress tolerance of intertidal seaweeds, providing opportunities for research ranging from field ecology to molecular biology and biochemistry.

Molecular Dynamics Simulation of Ion Mobility. 2. Alkali Metal and Halide Ions Using the SPC/E Model for Water at 25 °C†

Abstract: We present results of computer simulations of the mobilities of the alkali metal ions (Li+, Na+, K+, Rb+, and Cs+) and the halides (F-, Cl-, Br-, and I-) at 25 °C using the SPC/E model for water and ion−water parameters fitted to the binding energies of small clusters of ions. A simple truncation of the ion−water and water−water potentials was used, and the mobilities calculated from the mean square displacement and the velocity autocorrelation functions, respectively, were found to be in good agreement with each other. The calculations demonstrate, for the first time, cation and anion mobilities that fall on separate curves, as functions of ion size, with distinct maxima. This is in complete accord with experimental trends observed in water at 25 °C. The cation mobilities are also in better agreement with the measured values than the calculations done earlier (J. Chem. Phys. 1994, 101, 6964) using the TIP4P model. The mobilities of the halides calculated here for the SPC/E model are however slightly lowe...

Stress tolerance in intertidal seaweeds

Abstract: Intertidal seaweeds are periodically exposed to air where they experience a variety of potentially stressful environmental conditions, including nutrient limitation, high light, high and low temperature, desiccation, and osmotic stress. This paper considers the current understanding of stress tolerance in intertidal seaweeds and discusses ways in which future research could increase our understanding of the role of environmental factors in the ecology and physiology of these algae. We believe research is required in at least three areas. 1) Laboratory physiological studies have established that correlations exist between stress tolerance and the vertical distribution of species. However, little information is available on the importance of stress in determining community structure in nature. Field experiments are essential to relate the impact of single or multiple stresses on the survival, growth, and reproductive output of macroalgae. In paticular, it is necessary to clarify the role of sublethal stress in determining the outcome of competitive interactions. 2) With the exception of obvious lethal effects or damage associated with extreme environmental conditions, such as unusually hot and dry weather, it is difficult to evaluate the occurrence and severity of stress in natural populations of seaweeds. There is a need to develop molecular and biochemical markers specific for individual stresses or groups of stresses to allow the unambiguous and direct determination of stress in situ. 3) Despite the apparent importance of stress in intertidal seaweeds, we are largely ignorant of the mechanistic basis of tolerance. The application of currently available tools of molecular and cell biology to the investigation of stress-induced transcriptional and translational changes could enormously increase our understanding of both the sites of, and pathways involved in, stress tolerance. In summary, there are numerous unanswered fundamental questions about the stress tolerance of intertidal seaweeds, providing opportunities for research ranging from field ecology to molecular biology and biochemistry.

Social competence and behavior evaluation in children ages 3 to 6 years: The short form (SCBE-30).

Abstract: The factor structure and scale characteristics of the shortened version ofthe Social Competence and Behavior Evaluation Scale (SCBE; P J LaFreniere & J E Dumas, 1995) are presented for a Quebec sample and 3 US samples, as well as age and gender differences in the prevalence of emotional and behavioral problems and social competence throughout the preschool years Principal-components analyses identified 3 factors in all 4 samples: social competence (SC); anger-aggression (AA); and anxiety-withdrawal (AW) Each 10-item scale was shown to have high interrater and test-retest reliability, internal consistency, and temporal stability over a 6-month period Across all samples, boys were rated substantially higher on AA and lower on SC scales than girls, though no trends toward a sex difference in AW were evident A stepwise progression in SC with increasing age was apparent in all samples AA and AW behaviors showed a decline in the US, but not in the Quebec sample

Geoarchaeological Evidence from Peru for a 5000 Years B.P. Onset of El Niño

Abstract: For the tropical west coast of South America, where El Nino/Southern Oscillation (ENSO) is most pronounced, archaeological and associated paleontological deposits in northern Peru revealed a major climate change at about 5000 years before the present (yr B.P.). The data implied the presence of stable, warm tropical water as far south as 10°S during the early mid-Holocene (about 8000 to 5000 yr B.P.). These data suggest that ENSO did not occur for some millennia preceding 5000 yr B.P., when global and regional climate was warmer than today.

The impacts of mobile fishing gear on seafloor habitats in the gulf of Maine (Northwest Atlantic): Implications for conservation of fish populations

Abstract: Fishing gear alters seafloor habitats, but the extent of these alterations, and their effects, have not been quantified extensively in the northwest Atlantic. Understanding the extent of these impacts, and their effects on populations of living marine resources, is needed to properly manage current and future levels of fishing effort and fishing power. For example, the entire U.S. side of the Gulf of Maine was impacted annually by mobile fishing gear between 1984 and 1990, based on calculations of area swept by trawl and dredge gear. Georges Bank was imparted three to nearly four times annually during the same period. Studies at three sites in the Gulf of Maine (off Swans Island, Jeffreys Bank, and Stellwagen Bank) showed that mobile fishing gear altered the physical structure (=complexity) of benthic habitats. Complexity was reduced by direct removal of biogenic (e.g., sponges, hydrozoans, bryozoans, amphipod tubes, holothurians, shell aggregates) and‐ sedimentary (e.g., sand waves, depressions)...

Greater drought intensity and frequency before AD 1200 in the Northern Great Plains, USA

Abstract: EXTREME large-scale droughts in North America, such as the 'Dust Bowl' of the 1930s, have been infrequent events within the documented history of the past few hundred years, yet this record may not be representative of long-term patterns of natural variation of drought intensity and frequency. In the Great Plains region of central North America, historical droughts have persisted longer than in any other part of the United States1, but no detailed records of drought patterns in this region have hitherto been obtained that extend beyond the past 500 years. Here we present a reconstruction of drought intensity and frequency over the past 2,300 years in the Northern Great Plains, based on lake salinity fluctuations inferred from fossil diatom assemblages. This record, of sub-decadal resolution, suggests that extreme droughts of greater intensity than that of the 1930s were more frequent before AD 1200. This high frequency of extreme droughts persisted for centuries, and was most pronounced during AD 200–370, AD 700–850 and AD 1000–1200. We suggest that before AD 1200, the atmospheric circulation anomalies that produce drought today were more frequent and persistent.

Effects of ultraviolet radiation on corals and other coral reef organisms

Abstract: The discovery of the importance of solar ultraviolet radiation (UVR) as a factor affecting the biology of coral reefs dates only to about 1980. Interest has heightened during the past five years owing to the demonstration of loss of stratospheric ozone through human activities. We have only begun to document gross, qualitative effects of UVR on coral reef organisms, usually in experiments comparing the biological response to the presence or absence of UVR through the use of UV-cutoff filters, or to varying levels of UVR in transplantation studies. Most such studies have not distinguished between the effects of UVA (320–400 nm) and those of UVB (290–320 nm), although in the context of global change involving stratospheric ozone loss, it is the latter wavelengths that are relevant. To date we have been addressing physiological and ecological questions, not yet attempting to evaluate quantitatively the impact of forecast increases in solar UVB penetration. Interacting and synergistic effects of UVR with increased temperature, pollutants, sedimentation, visible light, etc. have scarcely been studied but will be essential to understanding and predicting the fate of coral reefs under conditions of global change. Here we comprehensively review the effects of UVR on corals and other reef macroorganisms, mindful that although much is known of proximal effects, little of this knowledge is directly useful in making long-term predictions regarding the health of coral reefs. We conclude that even small anthropogenic increases in UVB levels will have sublethal physiological manifestations in corals and other reef organisms, but that this will have relatively small impact on the distribution of reef corals and coral reefs, perhaps affecting their minimum depths of occurrence.

Children's social goals and self-efficacy perceptions as influences on their responses to ambiguous provocation

Abstract: This study examined whether children who vary in their behavioral responses (aggression vs. withdrawal vs. problem solving) to ambiguous provocation but who are similar in their attributional processes differ in their social goals and self-efficacy perceptions. In response to 10 hypothetical situations involving ambiguous provocation, fourth- and fifth-grade students (n = 781) indicated whether or not the protagonist intended to cause the harm and reported how they would respond to the protagonist's action. Newly developed measures assessed children's situated social goals and self-efficacy perceptions. Results indicated that the aggressive, withdrawn, and problem-solving responders differed in their social goals and self-efficacy perceptions. The strength of the findings, compared to earlier work on children's goals and self-efficacy perceptions, suggests the importance of a situated social-cognitive assessment in which children's thoughts are measured in a specific kind of social situation and are related to their reported behavior in the same type of situation.

Mycosporine-like amino acids provide protection against ultraviolet radiation in eggs of the green sea urchin strongylocentrotus droebachiensis

Abstract: A photoprotective role of ultraviolet radiation-absorbing mycosporine-like amino acids (MAAs) in eggs of the green sea urchin Strongylocentrotus droebachiensis was demonstrated by comparing UV-induced delays in the first division of embryos having either high or low concentrations of MAAs. Embryos from adult urchins fed Laminaria saccharina (no MAAs) had low concentrations of MAAs and experienced a significantly longer UV-induced delay in cleavage (25.1%) than MAA-rich embryos from adults fed Mastocarpus stellatus (12.8% delay) or a combination diet of both macroalgae (12.3% delay). Collectively, these embryos displayed a significant inverse logarithmic relationship between MAA concentration and percentage cleavage delay, so that the greater the MAA concentration in the eggs, the less they were affected by UV radiation. This is the first study to examine such MAA manipulation of cellular MAA concentrations with no prior UV exposure of the experimental subjects. Concentrations of MAAs were also measured in unfertilized eggs, blastulae, gastrulae and early pluteus larvae, providing the first documentation of changes in MAAs during embryological and larval development. The concentration of shinorine (the principal MAA in the eggs) did not change during short-term UV exposure in vivo or long-term exposure in vitro; such photostability is a useful attribute of a natural sunscreen.

Successful external fertilization in turbulent environments

Abstract: Mathematical and experimental simulations predict that external fertilization is unsuccessful in habitats characterized by high water motion A key assumption of such predictions is that gametes are released in hydrodynamic regimes that quickly dilute gametes We used fucoid seaweeds to examine whether marine organisms in intertidal and subtidal habitats might achieve high levels of fertilization by restricting their release of gametes to calm intervals Fucus vesiculosus L (Baltic Sea) released high numbers of gametes only when maximal water velocities were below ca 02 m/s immediately prior to natural periods of release, which occur in early evening in association with lunar cues Natural fertilization success measured at two sites was always close to 100% Laboratory experiments confirmed that (i) high water motion inhibits gamete release by F vesiculosus and by the intertidal fucoids Fucus distichus L (Maine) and Pelvetia fastigiata (J Ag) DeToni (California), and (ii) showed that photosynthesis is required for high gamete release These data suggest that chemical changes in the boundary layer surrounding adults during photosynthesis and/or mechanosensitive channels may modulate gamete release in response to changing hydrodynamic conditions Therefore, sensitivity to environmental factors can lead to successful external fertilization, even for species living in turbulent habitats

The Effect of Agricultural Policies on Land Use and Environmental Quality

Abstract: In this paper I consider the environmental quality gains that may be achieved by reducing agricultural income supports. A new methodology is developed to estimate land use shares. In an application to Wisconsin, milk price support reductions result in shifts of marginal agricultural land to forest, reducing soil erosion and providing off-site water quality improvements. The environmental benefits are estimated to be at least as large as the decreased welfare burden on consumers and taxpayers, indicating a central role for environmental quality considerations in motivating policy reforms and a more efficient means of achieving the environmental quality goals of land retirement programs.

Thermodynamic Effects of Formamide on DNA Stability

Abstract: Formamide lowers melting temperatures (Tm) of DNAs linearly by 2.4-2.9 degrees C/mole of formamide (C(F)) depending on the (G+C) composition, helix conformation and state of hydration. The inherent cooperativity of melting is unaffected by the denaturant. dTm/dC(F)for 11 plasmid domains of 0.23 coil transitions. Results indicate that formamide has a destabilizing effect on the helical state, and that sequence-dependent variations in hydration patterns are primarily responsible for small variations in sensitivity to the denaturant. The average unit transition enthalpy delta H(m)[see text for complete expression], exhibits a biphasic dependence on formamide concentration. The initial drop of -0.8 kcal/mol bp at low formamide concentrations is attributable to a delta delta H(m)[see text for complete expression], for exchange of solvent in the vicinity of the helix: displacement by formamide of weakly bound hydrate or counterion. The phenomenological effects are equivalent to lowering the bulk counterion concentration. Poly(dA.dT) exhibits a much lower sensitivity to formamide, due to the specific pattern of tightly bound, immobilized water bridges that buttress the helix from within the narrow minor groove. Tracts of three (A.T)-pairs behave normally, but tracts of six exhibit the same level of reduced sensitivity as the polymer, suggesting a conformational shift as tracts are elongated beyond some critical length [McCarthy J.G. and Rich,A. (1991) Nucleic Acids Res. 19, 3421-3429].

Construction of a Personal Development Competitive Attitude Scale

Abstract: Theory development and research in the area of psychologically healthy competition has been impeded by the lack of a psychometrically sound instrument. Four studies were conducted as part of a research program designed to remedy this deficiency by constructing an individual difference measure of general personal development competitive attitude with satisfactory psychometric properties. In Studies 1 and 2, a 15-item scale was derived primarily through item-total correlational analysis; it demonstrated satisfactory internal and test-retest reliabilities. Studies 3 and 4 were concerned with establishing the construct validity of the scale. Both Studies 3 and 4 showed the scale's discriminant validity through its lack of association with hypercompetitiveness. In addition, its construct validity was seen in its negative association with neurosis and its positive links with personal and social self-esteem and optimal psychological health. Also, as expected, personal development competitiveness was positively correlated with needs for affiliation, whereas hypercompetitiveness was unrelated to affiliation needs. Although hypercompetitive individuals were more aggressive, dominant, and exhibitionistic, this was not the case for personal development competitors.

Children's Expression of Negative Affect: Reasons and Methods.

Abstract: This study examined the influence of socialization figures (mother, father, best friend, medium friend), emotion type (anger, sadness, physical pain ), age, and gender on 66 2nd and 71 5th-grade children's reasons for and methods of affect expression. Children reported expressing sadness in order to receive support, expressing pain because they perceived it was uncontrollable, and regulating anger due to negative consequences. Girls reported using verbal means to communicate emotion, whereas boys cited mild aggressive methods. Younger children indicated expressing emotion to receive assistance because they lack regulation skills, and to adhere to norms. Children expressed emotion in passive ways to fathers more than peers, and mothers were deemed by younger children as most accepting of displays of anger.

Late Cenozoic Antarctic paleoclimate reconstructed from volcanic ashes in the Dry Valleys region of southern Victoria Land

Abstract: We report the discovery of numerous in situ Miocene and Pliocene airfall volcanic ashes that occur within the hyperarid Dry Valleys region of the Transantarctic Mountains in southern Victoria Land, Antarctica. Ashes that occur above 1000 m elevation rest at the ground surface, covered only by a thin ventifact pavement 1 to 2 cm thick. The ash deposits are loose and unconsolidated and show no signs of chemical weathering. Laser-fusion 40 Ar/ 39 Ar analyses of volcanic crystals and glass shards indicate that the ashes range from 4.33 Ma to 15.15 Ma in age. The Arena Valley ash (4.33 ± 0.07 Ma) rests on the surface of a well-developed desert pavement and ultraxerous soil profile at 1410 m elevation. Lack of geomorphic evidence of liquid water on surficial sediments coeval and older than the Arena Valley ash, together with the pristine condition of volcanic crystals and lack of authigenic clay formation, indicates a cold desert at and since 4.33 Ma. The Beacon Valley ash (10.66 ± 0.29 Ma), the Koenig Valley ash (13.65 ± 0.06 Ma), and the Nibelungen Valley ash (15.15 ± 0.02 Ma) fill the upper half of relict sand-wedge troughs that form only in cold-desert conditions. The lack of authigenic clay-sized minerals in these ash deposits, along with preservation of sharp lateral contacts with surrounding sand-and-gravel deposits, suggests that frozen conditions (without rain or well-developed active layers during summer months) have persisted in Beacon, Koenig, and Nibelungen Valleys since ash deposition. Ash-avalanche deposits that rest on rectilinear slopes contain matrix ash dated to 7.42 ± 0.31 Ma in upper Arena Valley and 11.28 ± 0.05 Ma in lower Arena Valley. Little slope development has occurred since emplacement of these ash-avalanche deposits. Such slope stability is consistent with cold-desert conditions well below 0 °C. Taken together, these ash deposits point to persistent polar conditions similar to the present at elevations above 1000 m in the western Dry Valleys region during at least the last 15.0 m.y. This conclusion contradicts the view that, during part of the Pliocene epoch, East Antarctica was largely free of glacier ice and that scrub vegetation (Nothofagus, Southern Beech) survived along the Transantarctic Mountain front in the Dry Valleys region and to at least lat 86°S (Webb and Harwood, 1993). Instead, it supports marine and geomorphological evidence that calls for a stable Antarctic cryosphere, much the same as today, since middle Miocene time.

Consensus of an international panel on the clinical utility of bone mass measurements in the detection of low bone mass in the adult population.

Abstract: Low bone mass, in the asymptomatic patient, predicts future fracture risk as well as high cholesterol or high blood pressure predicts the risk of heart disease or stroke. In patients without fractures, osteoporosis can be diagnosed based on the extent of reduction in bone mass below mean peak bone mass of healthy young individuals. As bone mass decreases, fracture risk increases exponentially. Prevention of the first fracture is a clinical goal. Clinical situations in which an assessment of bone mass and fracture risk affects therapeutic decisions include estrogen deficiency, vertebral abnormalities, radiographic osteopenia, asymptomatic primary hyperparathyroidism, and longterm corticosteroid therapy. Serial measurements can also be used to monitor the effects of osteoporosis treatment in certain situations. The appropriate technique and skeletal site for bone mass measurements should be chosen based on the patient's circumstances. A clinical interpretation can enhance the value of computer-generated bone mass measurement reports and enhance decision making.

Polygynandry in Pseudotropheus zebra, a cichlid fish from Lake Malawi

Abstract: Parental care in the Malawian cichlid fishPseudotropheus zebra ‘BB’ is extensive and exclusively maternal; males contribute only genetic material. The costs of searching for multiple mates (in this case risk of predation on orally incubated eggs) suggested that females should be monandrous; microsatellite genetypes of seven brooding females and their young, however, reveal extensive multiple paternity in this species, with a mean of 3.8 paternal individuals per brood. Polygynandry inP. zebra is probably not maintained by selection for genetically diverse offspring; potential explanations include avoidance of inbreeding, and bet-hedging on other male characteristics that females are unable to evaluate when selecting a mate. The observed degree of multiple paternity strongly suggests that females are free to choose mates as they will, a prerequisite of many theories positing sexual selection as a key element in Malawi chichlid evolution. It should also result in elevation of effective population sizes, and thus be antagonistic to runaway evolution of male secondary sexual characteristics, but not necessarily to other modes of sexual selection.

Benchmarks for Managing Ecosystems: Are Human Activities Natural?

Abstract: For conservation biologists one of the fundamental goals of managing ecosystems is to maintain or restore their natural structure and ftinction (Noss & Cooperrider 1994). In ecological reserves we strive to attain this goal as completely as possible. Outside reserves we accept some compromise in reaching this goal-for example, by designing timber harvests to emulate natural disturbances. In both cases we have to decide on the benchmarks for designing and evaluating our management-in other words, the natural structures and functions that we seek to maintain, restore, and emulate. The most difficult part of this question often involves deciding what is natural. In the context of conservation, \"natural\" might mean without human influence. Used in this way it is an antonym of adjectives such as \"anthropogenic,\" \"cultural,\" and \"artificial.\" This usage establishes a clear, simple dichotomy based on the idea that humans are a unique species. Some people, however, are uncomfortable with the idea that humans are not natural because they are not making distinctions based on the context in which a word is used. For example, these people might think, incorrectly, that describing humans as natural in contexts such as \"she's a natural athlete\" means that human effects on ecosystems must also be natural. Even within the context of conservation some people are concerned that recognizing a dichotomy between nature and humanity will perpetuate abuses of nature. Conversely, some other people are primarily interested in being able to extract commodities from ecosystems without their activities being condemned as unnatural. Ambiguities in the definition of \"natural\" are particularly evident in discussions of benchmarks for managing ecosystems in the Western Hemisphere because there are two distinct periods of human influence, one beginning roughly 12,000 years ago with colonization by Asian people across Beringia and a second beginning about 500 years ago with European colonization. When asked to choose a temporal benchmark for managing ecosystems, most conservation biologists in this hemisphere choose pre-European colonization. This decision implies that European management of ecosystems has not been natural, but that Native American management was natural. One argument that Native American activities (most notably setting fires) were natural emphasizes that species have had a very long time12,000 years-in which to evolve in response to these manipulations. It is true that 12,000 years is 24 times longer than the period of European influence, but this is not a long period in evolutionary time. If we are concerned with the ability of species to evolve in response to human activities, one million years is a more relevant figure. One million years is a rough estimate of the average longevity of a given species (Jenkins 1992) and it suggests that species that have evolved in the western hemisphere will have experienced human influence during only a small portion of their existence. Another argument is that Native American activities were natural because they lived with nature in a more harmonious fashion than Europeans have. Certainly the limited population density and technology of Native Americans mitigated their impact, but consider two points. First, some Native Americans (e.g., Aztecs, Incans, and Mayas) did live in dense populations that must have had profound impacts on local ecosystems. Dense populations probably existed elsewhere (e.g., the southeastern United States; Delcourt et al. 1986), but we tend to overlook these groups because they left few monumental structures or because they were decimated by diseases introduced by the earliest European explorers and had largely disappeared when later settlers arrived. Second, many biologists believe that hunting by Native Americans played a major role in the extinction of over 30 genera of large mammals, such as antelopes, mammoths, horses, and ground sloths (Martin & Klein, 1984). In contrast, the only large mammal extinctions attributable to European colonization (full species, not subspecies) were the loss of the Steller's sea cow and the Caribbean monk seal. In short, whereas the overall ecological impact of Native Americans was much less than that of Europeans, it was significant in certain times and places. How well do these two arguments apply in the East-

Sexual receptivity in insects.

Abstract: Sexual receptivity is female behavior that allows or helps a male to fertilize her eggs; through this behavior, females play an active role in reproduction. Multiple signals may be used for receptivity or unreceptivity. Insect species exhibit three ontogenetic patterns of receptivity: cyclic, in which females alternately become receptive and unreceptive; brief, in which females mate during on short developmental period; and continuous. Primary (initial) receptivity may be stimulated or inhibited by diet, ovarian development, or juvenile hormone. In species with cyclic receptivity, remating may be inhibited by copulation itself, the presence of eggs, sperm stored in spermathecae, or seminal factors--usually peptides--secreted by the male accessory glands. In many species, there is substantial genetic variation for both primary receptivity and speed of remating. Several single-gene mutations reduce female receptivity; most of these mutations also impair sensory functioning.

Order out of Chaos

Abstract: The current crisis in the world's fisheries indicates the need for a different management method than that now used by Western scientists, which regulates the quantity of fish taken. The authors propose a method called parametric management, which takes into account the complex, chaotic nature offish stocks and emphasizes preserving regular biological processes in the life cycle of fish by controlling how people fish. Supporting data come from 28 folk societies, the Maine lobster industry, and the authors' mathematical model of fish stocks.