Showing papers by "Miami University published in 2009"

Generalized linear mixed models: a practical guide for ecology and evolution

Abstract: How should ecologists and evolutionary biologists analyze nonnormal data that involve random effects? Nonnormal data such as counts or proportions often defy classical statistical procedures. Generalized linear mixed models (GLMMs) provide a more flexible approach for analyzing nonnormal data when random effects are present. The explosion of research on GLMMs in the last decade has generated considerable uncertainty for practitioners in ecology and evolution. Despite the availability of accurate techniques for estimating GLMM parameters in simple cases, complex GLMMs are challenging to fit and statistical inference such as hypothesis testing remains difficult. We review the use (and misuse) of GLMMs in ecology and evolution, discuss estimation and inference and summarize 'best-practice' data analysis procedures for scientists facing this challenge.

Lakes and reservoirs as regulators of carbon cycling and climate

Abstract: We explore the role of lakes in carbon cycling and global climate, examine the mechanisms influencing carbon pools and transformations in lakes, and discuss how the metabolism of carbon in the inland waters is likely to change in response to climate. Furthermore, we project changes as global climate change in the abundance and spatial distribution of lakes in the biosphere, and we revise the estimate for the global extent of carbon transformation in inland waters. This synthesis demonstrates that the global annual emissions of carbon dioxide from inland waters to the atmosphere are similar in magnitude to the carbon dioxide uptake by the oceans and that the global burial of organic carbon in inland water sediments exceeds organic carbon sequestration on the ocean floor. The role of inland waters in global carbon cycling and climate forcing may be changed by human activities, including construction of impoundments, which accumulate large amounts of carbon in sediments and emit large amounts of methane to the atmosphere. Methane emissions are also expected from lakes on melting permafrost. The synthesis presented here indicates that (1) inland waters constitute a significant component of the global carbon cycle, (2) their contribution to this cycle has significantly changed as a result of human activities, and (3) they will continue to change in response to future climate change causing decreased as well as increased abundance of lakes as well as increases in the number of aquatic impoundments.

Lakes and reservoirs as sentinels, integrators, and regulators of climate change

Abstract: Climate change is generating complex responses in both natural and human ecosystems that vary in their geographic distribution, magnitude, and timing across the global landscape. One of the major issues that scientists and policy makers now confront is how to assess such massive changes over multiple scales of space and time. Lakes and reservoirs comprise a geographically distributed network of the lowest points in the surrounding landscape that make them important sentinels of climate change. Their physical, chemical, and biological responses to climate provide a variety of information-rich signals. Their sediments archive and integrate these signals, enabling paleolimnologists to document changes over years to millennia. Lakes are also hot spots of carbon cycling in the landscape and as such are important regulators of climate change, processing terrestrial and atmospheric as well as aquatic carbon. We provide an overview of this concept of lakes and reservoirs as sentinels, integrators, and regulators of climate change, as well as of the need for scaling and modeling these responses in the context of global climate change. We conclude by providing a brief look to the future and the creation of globally networked sensors in lakes and reservoirs around the world.

Dynamic and Efficient Key Management for Access Hierarchies

Abstract: Hierarchies arise in the context of access control whenever the user population can be modeled as a set of partially ordered classes (represented as a directed graph). A user with access privileges for a class obtains access to objects stored at that class and all descendant classes in the hierarchy. The problem of key management for such hierarchies then consists of assigning a key to each class in the hierarchy so that keys for descendant classes can be obtained via efficient key derivation.We propose a solution to this problem with the following properties: (1) the space complexity of the public information is the same as that of storing the hierarchy; (2) the private information at a class consists of a single key associated with that class; (3) updates (i.e., revocations and additions) are handled locally in the hierarchy; (4) the scheme is provably secure against collusion; and (5) each node can derive the key of any of its descendant with a number of symmetric-key operations bounded by the length of the path between the nodes. Whereas many previous schemes had some of these properties, ours is the first that satisfies all of them. The security of our scheme is based on pseudorandom functions, without reliance on the Random Oracle Model.Another substantial contribution of this work is that we are able to lower the key derivation time at the expense of modestly increasing the public storage associated with the hierarchy. Insertion of additional, so-called shortcut, edges, allows to lower the key derivation to a small constant number of steps for graphs that are total orders and trees by increasing the total number of edges by a small asymptotic factor such as O(log*n) for an n-node hierarchy. For more general access hierarchies of dimension d, we use a technique that consists of adding dummy nodes and dimension reduction. The key derivation work for such graphs is then linear in d and the increase in the number of edges is by the factor O(logd − 1n) compared to the one-dimensional case.Finally, by making simple modifications to our scheme, we show how to handle extensions proposed by Crampton [2003] of the standard hierarchies to “limited depth” and reverse inheritance.

The Acinetobacter baumannii 19606 OmpA Protein Plays a Role in Biofilm Formation on Abiotic Surfaces and in the Interaction of This Pathogen with Eukaryotic Cells

Abstract: The ability of Acinetobacter baumannii to adhere to and persist on surfaces as biofilms could be central to its pathogenicity. The production of pili and a biofilm-associated protein and the expression of antibiotic resistance are needed for robust biofilm formation on abiotic and biotic surfaces. This multistep process also depends on the expression of transcriptional regulatory functions, some of which could sense nutrients available to cells. This report extends previous observations by showing that although outer membrane protein A (OmpA) of A. baumannii 19606 plays a partial role in the development of robust biofilms on plastic, it is essential for bacterial attachment to Candida albicans filaments and A549 human alveolar epithelial cells. In contrast to abiotic surfaces, the interaction with biotic surfaces is independent of the CsuA/BABCDE-mediated pili. The interaction of A. baumannii 19606 with fungal and epithelial cells also results in their apoptotic death, a response that depends on the direct contact of bacteria with these two types of eukaryotic cells. Furthermore, the bacterial adhesion phenotype correlates with the ability of bacteria to invade A549 epithelial cells. Interestingly, the killing activity of cell-free culture supernatants proved to be protease and temperature sensitive, suggesting that its cytotoxic activity is due to secreted proteins, some of which are different from OmpA.

FGF23 decreases renal NaPi-2a and NaPi-2c expression and induces hypophosphatemia in vivo predominantly via FGF receptor 1.

Abstract: Fibroblast growth factor-23 (FGF23) is a phosphaturic hormone that contributes to several hypophosphatemic disorders by reducing the expression of the type II sodium-phosphate cotransporters (NaPi-...

Solution-Based Evolution and Enhanced Methanol Oxidation Activity of Monodisperse Platinum-Copper Nanocubes**

Abstract: Shape-controlled catalysis: High-quality Pt-Cu nanocubes with an average size of about 8 nm (see picture, scale bar = 20 nm) were synthesized from a high-temperature organic solution system in the presence of various capping ligands. These cubic Pt-Cu nanocrystals terminated with {100} facets demonstrated a superior catalytic activity towards methanol oxidation compared to similar sized Pt-Cu and Pt nanospheres.

Differential Item Functioning

Abstract: One of the key techniques researchers use in measurement is to investigate Differential Item Functioning (DIF). In this chapter, we give examples to help define what DIF is and why it is important to understand. Readers are provided with guidance on how to interpret numerous critical Winsteps tables which help one identify items exhibiting DIF. Particular attention is given to how DIF is related to bias and construct validity. The chapter concludes by guiding readers through the steps they might take if they identify an item with DIF for gender. Steps are presented so measures can be computed while retaining the problematic item. This is done by viewing the item as a different item for males and females. The chapter finishes up with a summary discussion between the two students, Keywords and Phrases, Quick Tips, Data Files, References, and Additional Readings. As in almost all chapters, sample analyses are used to reinforce the chapter topic.

Stand by me: The effects of peer and teacher support in mitigating the impact of bullying on quality of life

Abstract: Bullying is one of the most common forms of school violence. Engagement in bullying has been shown to have adverse effects on perpetrators and victims of bullying. In this study, the impact of bullying on well-being (quality of life/life satisfaction) was explored in a sample of elementary and middle school children (N = 4,331). Results suggest that students who bully and/or are bullied experience reduced life satisfaction and support from peers and teachers compared to “bystanders” (children who are neither victims nor perpetrators of bullying). Mediational analyses demonstrate that peer and teacher support might mitigate the impact of bullying on the quality of life of victims. This study underscores the value of efforts to promote social support from peers and teachers in both universal bullying prevention programs and school climate initiatives. Furthermore, results support further investigation into the possible contributions of bystanders in supporting school-wide bullying prevention/school climate strategies. © 2009 Wiley Periodicals, Inc.

Mathematics Teacher TPACK Standards and Development Model

Abstract: What knowledge is needed to teach mathematics with digital technologies? The overarching construct, called technology, pedagogy, and content knowledge (TPACK), has been proposed as the interconnection and intersection of technology, pedagogy, and content knowledge. Mathematics Teacher TPACK Standards offer guidelines for thinking about this construct. A Mathematics Teacher Development Model describes the development of TPACK toward meeting these standards. The standards and model provide structured detail to further the work of various groups. The proposals may guide teachers, researchers, teacher educators, professional development consultants, and school administrators in the development and evaluation of professional development activities, mathematics education programs, and school mathematics programs. Contemporary Issues in Technology and Teacher Education, 9(1) 5 In 1986 Lee Shulman launched a new way of thinking about the knowledge teachers need for teaching with a construct that he called pedagogical content knowledge (PCK). This new way of thinking about the knowledge teachers need for teaching called for the integration of content knowledge (the knowledge previously considered the primary knowledge for teachers) and pedagogical knowledge (the knowledge about teaching and learning). The intersection of these two knowledge bases, PCK, was described as the way of representing and formulating subject matter knowledge, the knowledge that makes the subject matter comprehensible to learners (Shulman, 1986, 1987; Wilson, Shulman, & Richert, 1987). More specifically, Shulman (1986) characterized a teacher’s PCK as knowledge of the most regularly taught topics in one’s subject area, the most useful forms of representation of those ideas, the most powerful analogies, illustrations, examples, explanations, and demonstrations ... including an understanding of what makes the learning of specific concepts easy or difficult: the concepts and preconceptions that students of different ages and backgrounds bring with them to the learning. ( p. 9) During those early discussions of the construction of knowledge growth in teaching, teacher preparation programs were challenged to determine how they might guide the development of this teacher knowledge. Some programs honed in on the development of six primary domains of knowledge essential for effective instruction: subject matter knowledge, pedagogical knowledge, knowledge of schools, knowledge of learners, and curricular knowledge, with PCK as the essence of the intersection of these five domains of knowledge (Niess, 2001). The relationship was viewed as a complex and integrated structure where no domain was totally distinct or separate from the other, with the relative amount of overlap and interaction among the domains constantly changing as preservice teachers made sense of and prioritized the multiple factors affecting student learning. Attention to PCK through research studies provided insight into the preparation of preservice mathematics teachers’ development of PCK (Ball, 1988; Civil, 1992; Grossman, 1991; McDiarmid, 1990; Simon & Brobeck, 1993; Simon & Mazza, 1993; Wilcox et al., 1990). Grossman’s (1989, 1990) research identified four central components of PCK to focus the description and understanding of the knowledge needing development in the preparation programs: (a) an overarching conception of what it means to teach a particular subject; (b) knowledge of instructional strategies and representations for teaching particular subject matter topics; (c) knowledge of students’ understandings, thinking, and learning in the subject area; (d) knowledge of curriculum and curriculum materials with learning subject matter (Borko & Purtnam, 1996). As this understanding of PCK evolved, modern digital technologies also began to be recognized as useful for teaching and learning. During the late 1970s and 1980s, the focus in mathematics education was on identifying places in mathematics instruction for inserting digital technology applications. A myriad of software programs afforded drill and practice in a variety of environments that were more entertaining than traditional paper-and-pencil worksheets for providing practice with computational skills. Graphing calculators offered capabilities for efficiently generating visuals of graphs useful for demonstrating mathematical ideas such as slope and y-intercept for linear functions and points of intersection for multiple functions. The primary vision for employing mathematical digital technologies was for demonstration and verification of ideas previously developed in the classroom. Calculators – from limited four-function calculators to scientific calculators – were Contemporary Issues in Technology and Teacher Education, 9(1) 6 restricted with the belief that these tools trivialized the mathematics rather than engaging students in learning mathematics. The lack of an in-depth integration of these technologies prompted Kaput’s (1992) lament that the “major limitations of computer use in the coming decades are likely to be less a result of technological limitations than a result of limited human imagination and the constraints of old habits and social structures” (p. 515). An examination of mathematics teachers’ PCK in the late 1980s and early 1990s revealed an overarching conception that teachers’ beliefs about how to teach mathematics generally were aligned with how they learned mathematics. Although a few teachers embraced the use of graphing calculators, spreadsheets, and software like Logo and Geometric Supposer, many did not. Mathematics teachers’ knowledge of instructional strategies and representations for teaching particular mathematical topics relegated the application of such digital technologies to demonstration, verification, and drill and practice. Their knowledge of students’ understandings, thinking, and learning in mathematics held to the importance of mastery of skills with paper and pencil prior to using modern digital technologies (Kastberg & Leatham, 2005; Walen, Williams, & Garner, 2003; Yoder, 2000). Furthermore, access to technology without necessary knowledge of related curriculum materials did not encourage teachers to incorporate the technology in their classroom instruction (Kastberg & Leatham, 2005). “In the absence of professional development on instructional technology and curriculum materials that integrate technology use into the lesson content, teachers are not particularly likely to embed technology-based or technology-rich activities into their courses” (Ferrini-Mundy & Breaux, 2008, p. 437438). Fast forward to 2008 to see that many mathematics teachers’ PCK lacks a solid and consistent integration of modern digital technologies in mathematics curriculum and instruction. Technologies, such as dynamic geometry tools or advanced graphing calculators with computer algebra systems (CAS), are primarily used for modeling and providing examples, where students imitate the actions and use the technologies for verification, demonstration, and drill and practice. In essence then, while digital technologies have evolved, strategies for their effective integration into the learning of mathematics have not evolved as rapidly. Mathematics TPACK: The Total Package for Teaching Mathematics As time shifted and digital technologies became more accessible and incorporated into citizens’ work and play, the International Society for Technology and Education (ISTE) challenged teachers to think about the technology skills and knowledge students would need in an increasingly technology savvy society. By the turn of the 21st century, the National Education Technology Standards for Students (NETS-S; ISTE, 2000) were released with the goal of supporting the evolution of effective use of appropriate technologies in school settings. ISTE recognized that these new standards called for different teacher knowledge than was currently operating in the schools. Within the following 2 years, the National Educational Technology Standards for Teachers (NETS-T; ISTE, 2002) were also released. Although embedded in a rapidly changing digital society, little real instructional change filtered into classrooms. Therefore, ISTE moved to shift the focus of the NETS-S from basic skills and knowledge needed to operate the technology to learning how to effectively use the technology; the NETS-S were updated in 2007. Subsequently, to assist Contemporary Issues in Technology and Teacher Education, 9(1) 7 teachers in responding to the call of learning environments supported by multiple technologies, a revision of the teacher standards was released in 2008. These standards effectively shifted the focus on digital technologies toward a concern about the curriculum and instructional uses of the digital tools and resources. Earle (2002) framed this shift most clearly: Integrating technology is not about technology – it is primarily about content and effective instructional practices. Technology involves the tools with which we deliver content and implement practices in better ways. Its focus must be on curriculum and learning. Integration is defined not by the amount or type of technology used, but by how and why it is used. (p. 8) Numerous researchers focused on the integration of technology, content, and pedagogy in much the same way that Shulman described PCK, to gain a broader perspective on the knowledge teachers need for teaching with technology. In essence, they defined technological pedagogical content knowledge (TPCK) as that body of knowledge teachers needed for teaching with and about technology in their assigned subject areas and grade levels. TPCK was presented as the interconnection and intersection of content, pedagogy (teaching and student learning), and technology (Margerum-Leys & Marx, 2002; Mishra & Koehler, 2006; Niess, 2005; Pierson, 2001). The idea of TPCK developed to the point that the American Association of Colleges of

Regulation of Acinetobacter baumannii biofilm formation.

Abstract: Acinetobacter baumannii is a Gram-negative opportunistic nosocomial pathogen. This microorganism survives in hospital environments despite unfavorable conditions such as desiccation, nutrient starvation and antimicrobial treatments. It is hypothesized that its ability to persist in these environments, as well as its virulence, is a result of its capacity to form biofilms. A. baumannii forms biofilms on abiotic surfaces such as polystyrene and glass as well as biotic surfaces such as epithelial cells and fungal filaments. Pili assembly and production of the Bap surface-adhesion protein play a role in biofilm initiation and maturation after initial attachment to abiotic surfaces. Furthermore, the adhesion and biofilm phenotypes of some clinical isolates seem to be related to the presence of broad-spectrum antibiotic resistance. The regulation of the formation and development of these biofilms is as diverse as the surfaces on which this bacterium persists and as the cellular components that participate in this programmed multistep process. The regulatory processes associated with biofilm formation include sensing of bacterial cell density, the presence of different nutrients and the concentration of free cations available to bacterial cells. Some of these extracellular signals may be sensed by two-component regulatory systems such as BfmRS. This transcriptional regulatory system activates the expression of the usher-chaperone assembly system responsible for the production of pili, needed for cell attachment and biofilm formation on polystyrene surfaces. However, such a system is not required for biofilm formation on abiotic surfaces when cells are cultured in chemically defined media. Interestingly, the BfmRS system also controls cell morphology under particular culture conditions.

Anti-cancer, anti-diabetic and other pharmacologic and biological activities of penta-galloyl-glucose

Abstract: 1, 2, 3, 4, 6-penta-O-galloyl-β-D-glucose (PGG) is a polyphenolic compound highly enriched in a number of medicinal herbals. Several in vitro and a handful of in vivo studies have shown that PGG exhibits multiple biological activities which implicate a great potential for PGG in the therapy and prevention of several major diseases including cancer and diabetes. Chemically and functionally, PGG appears to be distinct from its constituent gallic acid or tea polyphenols. For anti-cancer activity, three published in vivo preclinical cancer model studies with PGG support promising efficacy to selectively inhibit malignancy without host toxicity. Potential mechanisms include anti-angiogenesis; anti-proliferative actions through inhibition of DNA replicative synthesis, S-phase arrest, and G1 arrest; induction of apoptosis; anti-inflammation; and anti-oxidation. Putative molecular targets include p53, Stat3, Cox-2, VEGFR1, AP-1, SP-1, Nrf-2, and MMP-9. For anti-diabetic activity, PGG and analogues appear to improve glucose uptake. However, very little is known about the absorption, pharmacokinetics, and metabolism of PGG, or its toxicity profile. The lack of a large quantity of highly pure PGG has been a bottleneck limiting in vivo validation of cancer preventive and therapeutic efficacies in clinically relevant models.

E2f1-3 switch from activators in progenitor cells to repressors in differentiating cells.

Abstract: In the established model of mammalian cell cycle control, the retinoblastoma protein (Rb) functions to restrict cells from entering S phase by binding and sequestering E2f activators (E2f1, E2f2 and E2f3), which are invariably portrayed as the ultimate effectors of a transcriptional program that commit cells to enter and progress through S phase. Using a panel of tissue-specific cre-transgenic mice and conditional E2f alleles we examined the effects of E2f1, E2f2 and E2f3 triple deficiency in murine embryonic stem cells, embryos and small intestines. We show that in normal dividing progenitor cells E2f1-3 function as transcriptional activators, but contrary to the current view, are dispensable for cell division and instead are necessary for cell survival. In differentiating cells E2f1-3 function in a complex with Rb as repressors to silence E2f targets and facilitate exit from the cell cycle. The inactivation of Rb in differentiating cells resulted in a switch of E2f1-3 from repressors to activators, leading to the superactivation of E2f responsive targets and ectopic cell divisions. Loss of E2f1-3 completely suppressed these phenotypes caused by Rb deficiency. This work contextualizes the activator versus repressor functions of E2f1-3 in vivo, revealing distinct roles in dividing versus differentiating cells and in normal versus cancer-like cell cycles.

Microbe-clay mineral interactions

Abstract: Clays and clay minerals are common components in soils, sediments, and sedimentary rocks, and they play an important role in many environmental processes. Iron is ubiquitous in clays and clay minerals and its oxidation state, in part, controls the physical and chemical properties of these fine-grained minerals. The structural ferric iron in clay minerals can be reduced either chemically or biologically. Biological reductants include mesophilic and thermophilic microorganisms from diverse environments such as soils, sediments, sedimentary rocks, and hydrothermal hot springs. Multiple clay minerals have been used for microbial reduction studies, including dioctahedral smectiteillite series, palygorskite, chlorite, and their various mixtures in natural soils and sediments. All of these clay minerals are reducible by microorganisms under various conditions with smectite (nontronite) being the most reducible and illite the least. The rate and extent of bioreduction depends on many experimental factors, such as the type of microorganisms and clay minerals, solution chemistry, and temperature. Despite significant efforts, current understanding of the mechanisms of microbial reduction of ferric iron in clay minerals is still limited. Whereas some studies have presented evidence for a solid-state reduction mechanism, others argue that the clay mineral structure partially dissolves when the extent of reduction is high. This inconsistency may be related to several experimental conditions, and their specific effects are discussed in this paper. Whereas past experiments have been largely conducted in well-controlled laboratory systems, recent efforts have attempted to transfer knowledge to the field to improve our understanding of more complex soil systems for better agricultural practices. Biologically reduced clay minerals are also important agents in remediating inorganic and organic contaminants in soil and groundwater systems. This paper reviews the most recent developments and suggests some directions for future research.

Sentinels of Change

Abstract: Lakes and reservoirs provide key insights into the effects and mechanisms of climate change.

Geochemical and temporal evolution of Cenozoic magmatism in western Turkey: Mantle response to collision, slab break-off, and lithospheric tearing in an orogenic belt

Abstract: Post-collisional magmatism in western Anatolia began in the Eocene, and has occurred in discrete pulses throughout the Cenozoic as it propagated from north to south, producing volcano- plutonic associations with varying chemical compositions. This apparent SW migration of magma- tism and accompanying extension through time was a result of the thermally induced collapse of the western Anatolian orogenic belt, which formed during the collision of the Sakarya and Tauride-Anatolide continental blocks in the late Paleocene. The thermal input and melt sources for this prolonged magmatism were provided first by slab break-off-generated aesthenospheric flow, then by lithospheric delamination-related aesthenospheric flow, followed by tectonic extension-driven upward aesthenospheric flow. The first magmatic episode is represented by Eocene granitoid plutons and their extrusive carapace that are linearly distributed along the Izmir- Ankara suture zone south of the Marmara Sea. These suites show moderately evolved com- positions enriched in incompatible elements similar to subduction zone-influenced subalkaline magmas. Widespread Oligo-Miocene volcanic and plutonic rocks with medium- to high-K calc- alkaline compositions represent the next magmatic episode. Partial melting and assimilation- fractional crystallization of enriched subcontinental lithospheric mantle-derived magmas were important processes in the genesis and evolution of the parental magmas, which experienced decreasing subduction influence and increasing crustal contamination during the evolution of the Eocene and Oligo-Miocene volcano-plutonic rocks. Collision-induced lithospheric slab break-off provided an influx of aesthenospheric heat and melts that resulted in partial melting of the previously subduction-metasomatized mantle lithosphere beneath the suture zone, producing the Eocene and Oligo-Miocene igneous suites. The following magmatic phase during the middle Miocene (16- 14 Ma) developed mildly alkaline bimodal volcanic rocks that show a decreasing amount of crustal contamination and subduction influence in time. Both melting of a subduc- tion-modified lithospheric mantle and aesthenospheric mantle-derived melt contribution played a significant role in the generation of the magmas of these rocks. This magmatic episode was attended by region-wide extension that led to the formation of metamorphic core complexes and graben systems. Aesthenospheric upwelling caused by partial delamination of the lithospheric root beneath the western Anatolian orogenic belt was likely responsible for the melt evolution of these mildly alkaline volcanics. Lithospheric delamination may have been caused by 'peeling off' during slab rollback. The last major phase of magmatism in the region, starting c.12 Ma, is represented by late Miocene to Quaternary alkaline to super-alkaline volcanic rocks that show OIB-like geochemical features with progressively more potassic compositions increasing toward south in time. These rocks are spatially associated with major extensional fault systems that acted as natural conduits for the transport of uncontaminated alkaline magmas to the surface. The melt source for this magmatic phase carried little or no subduction component and was pro- duced by the decompressional melting of aesthenospheric mantle, which flowed in beneath the atte- nuated continental lithosphere in the Aegean extensional province. This time-progressive evolution of Cenozoic magmatism and extension in western Anatolia has been strongly controlled by the interplay between regional plate-tectonic events and the mantle dynamics, and provides a realistic template for post-collisional magmatism and crustal extension in many orogenic belts.

A review on polymer heat exchangers for HVAC&R applications

Abstract: Because of their low thermal conductivity, polymers are not commonly considered as a material to construct heat exchangers, except for specific applications, e.g. heat recovery from solvent laden streams, where exotic alloys are required to prevent corrosion. In this review the material properties of polymers are examined, as well as the current state of the art of polymer matrix composites. It is shown that these materials do hold promise for use in the construction of heat exchangers in HVAC&R applications, but that a considerable amount of research is still required into material properties and life-time behavior. A successful application of polymers or polymer matrix composites is based on careful material selection and modification of the design to fully exploit the material properties, as is demonstrated through a series of examples.

Subducting Slab Ultra-Slow Velocity Layer Coincident with Silent Earthquakes in Southern Mexico

Abstract: Great earthquakes have repeatedly occurred on the plate interface in a few shallow-dipping subduction zones where the subducting and overriding plates are strongly locked. Silent earthquakes (or slow slip events) were recently discovered at the down-dip extension of the locked zone and interact with the earthquake cycle. Here, we show that locally observed converted SP arrivals and teleseismic underside reflections that sample the top of the subducting plate in southern Mexico reveal that the ultra-slow velocity layer (USL) varies spatially (3 to 5 kilometers, with an S-wave velocity of ~2.0 to 2.7 kilometers per second). Most slow slip patches coincide with the presence of the USL, and they are bounded by the absence of the USL. The extent of the USL delineates the zone of transitional frictional behavior.

Climate-induced changes in the small mammal communities of the Northern Great Lakes Region

Abstract: We use museum and other collection records to document large and extraordinarily rapid changes in the ranges and relative abundance of nine species of mammals in the northern Great Lakes region (white-footed mice, woodland deer mice, southern red-backed voles, woodland jumping mice, eastern chipmunks, least chipmunks, southern flying squirrels, northern flying squirrels, common opossums). These species reach either the southern or the northern limit of their distributions in this region. Changes consistently reflect increases in species of primarily southern distribution (white-footed mice, eastern chipmunks, southern flying squirrels, common opossums) and declines by northern species (woodland deer mice, southern red-backed voles, woodland jumping mice, least chipmunks, northern flying squirrels). White-footed mice and southern flying squirrels have extended their ranges over 225 km since 1980, and at particularly well-studied sites in Michigan's Upper Peninsula, small mammal assemblages have shifted from numerical domination by northern species to domination by southern species. Repeated resampling at some sites suggests that southern species are replacing northern ones rather than simply being added to the fauna. Observed changes are consistent with predictions from climatic warming but not with predictions based on recovery from logging or changes in human populations. Because of the abundance of these focal species (the eight rodent species make up 96.5% of capture records of all forest-dwelling rodents in the region and 70% of capture records of all forest-dwelling small mammals) and the dominating ecological roles they play, these changes substantially affect the composition and structure of forest communities. They also provide an unusually clear example of change that is likely to be the result of climatic warming in communities that are experienced by large numbers of people.

Standards for associations and alliances of the U.S. National Vegetation Classification

Abstract: This article provides guidelines for the description, documentation, and review of proposals for new or revised plant associations and alliances to be recognized as units of vegetation within the U.S. National Vegetation Classification (NVC). By setting forth standards for field records, analysis, description, peer review, and archiving, the Ecological Society of America's Vegetation Classification Panel, in collaboration with the U.S. Federal Geographic Data Committee, NatureServe, and others, seeks to advance our common understanding of vegetation and improve our capability to sustain and restore natural systems. We provide definitions for the two floristic levels of the NVC hierarchy: associations and alliances. This is followed by a description of standards for field plot records and the identification and classification of vegetation types. Procedures for review and evaluation of proposed additions and revisions of types are provided, as is a structure for data archiving and dissemination. These proc...