Showing papers by "University of Maine published in 1999"

Batrachochytrium dendrobatidis gen. et sp. nov., a chytrid pathogenic to amphibians

Abstract: Captive and wild frogs from North and Central America and Australia recently have died with epidermal infections by chytridiomycete fungi. We isolated a chytridiomycete into pure culture from a captive, blue poison dart frog that died at the Na- tional Zoological Park in Washington, D.C. Using this isolate, we photographed developmental stages on nutrient agar, examined zoospores with transmission electron microscopy, and inoculated test frogs. This inoperculate chytrid develops either monocentrically or colonially and has thread-like rhizoids that arise from single or multiple areas on the developing zoo- sporangium. The taxonomically important features of the kinetosomal region of the zoospore indicate that this chytrid is a member of the Chytridiales but differs from other chytrids studied with transmission electron microscopy. Its microtubule root, which be- gins at kinetosome triplets 9-1 and extends parallel to the kinetosome into the aggregation of ribosomes, is distinctive. Histologic examination of test frogs re- vealed that the pure culture infected the skin of test frogs, whereas the skin of control frogs remained free of infection. The fungus is described as Batrachochy-

Regional trends in aquatic recovery from acidification in North America and Europe

Abstract: Rates of acidic deposition from the atmosphere (‘acid rain’) have decreased throughout the 1980s and 1990s across large portions of North America and Europe1,2. Many recent studies have attributed observed reversals in surface-water acidification at national3 and regional4 scales to the declining deposition. To test whether emissions regulations have led to widespread recovery in surface-water chemistry, we analysed regional trends between 1980 and 1995 in indicators of acidification (sulphate, nitrate and base-cation concentrations, and measured (Gran) alkalinity) for 205 lakes and streams in eight regions of North America and Europe. Dramatic differences in trend direction and strength for the two decades are apparent. In concordance with general temporal trends in acidic deposition, lake and stream sulphate concentrations decreased in all regions with the exception of Great Britain; all but one of these regions exhibited stronger downward trends in the 1990s than in the 1980s. In contrast, regional declines in lake and stream nitrate concentrations were rare and, when detected, were very small. Recovery in alkalinity, expected wherever strong regional declines in sulphate concentrations have occurred, was observed in all regions of Europe, especially in the 1990s, but in only one region (of five) in North America. We attribute the lack of recovery in three regions (south/central Ontario, the Adirondack/Catskill mountains and midwestern North America) to strong regional declines in base-cation concentrations that exceed the decreases in sulphate concentrations.

Past and future grounding-line retreat of the West Antarctic Ice Sheet

Abstract: The history of deglaciation of the West Antarctic Ice Sheet (WAIS) gives clues about its future. Southward grounding-line migration was dated past three locations in the Ross Sea Embayment. Results indicate that most recession occurred during the middle to late Holocene in the absence of substantial sea level or climate forcing. Current grounding-line retreat may reflect ongoing ice recession that has been under way since the early Holocene. If so, the WAIS could continue to retreat even in the absence of further external forcing.

The nitrogen isotope biogeochemistry of sinking particles from the margin of the Eastern North Pacific

Abstract: The nitrogen isotopic composition of time-series sediment trap samples, dissolved NO~ , and surficial sediments was determined in three regions along the margin of the eastern North Pacific: Monterey Bay, San Pedro Basin, and the Gulf of California (Carmen and Guaymas Basins). Complex physical regimes are present in all three areas, and each is influenced seasonally by coastal upwelling. Nevertheless, sediment trap material evidently records the isotopic composition of new nitrogen sources, since average d15N is generally indistinguishable from d15N values for subsurface NO~ . Surficial sediments are also very similar to the average d15N value of the sediment traps, being within 1&. This di⁄erence in d15N between trap material and sediment is much less than the previously observed 4& di⁄erence for the deep sea. Better organic matter preservation at our margin sites is a likely explanation, which may be due to either low bottom O 2 concentrations or higher organic matter input to the sediments. All sites have d15N for sub-euphotic zone NO~ (8—10&) substantially elevated from the oceanic average (4.5—5&). This isotopic enrichment is a result of denitrification in suboxic subsurface waters (Gulf of California) or northward transport of denitrification influenced water (Monterey Bay and San Pedro Basin). Our results therefore suggest that downcore d15N data, depending on site location, would record the intensity of denitrification and the transport of its isotopic signature along the California margin. Temporal variations in d15N for the sediment traps do appear to respond to upwelling or convective injections of NO~ to surface waters as

Seasonal patterns and environmental control of carbon dioxide and water vapour exchange in an ecotonal boreal forest

Abstract: Carbon dioxide, water vapour, and sensible heat fluxes were measured above and within a spruce dominated forest near the southern ecotone of the boreal forest in Maine, USA.

Cutaneous Chytridiomycosis in Poison Dart Frogs (Dendrobates spp.) and White's Tree Frogs (Litoria Caerulea)

Abstract: 3. Brodey RS, Reid CF, Sauer RM: 1966, Metastatic bone neoplasms in the dog. J Am Vet Med Assoc 148:29–43. 4. Chin RP, Barr BC: 1990, Squamous cell carcinoma of the pharyngeal cavity in a Jersey black giant rooster. Avian Dis 34: 775–778. 5. Head KW: 1990, Tumors of the alimentary tract. In: Tumors in domestic animals, ed. Moulton JE, 3rd ed., pp. 347–435. University of California Press, Berkeley, CA. 6. Kotwall C, Sako K, Razak MS, et al.: 1987, Metastatic patterns in squamous cell cancer of the head and neck. Am J Surg 154: 439–442. 7. Latimer KS: 1994, Oncology. In: Avian medicine: principles and application, ed. Ritchie BW, Harrison GJ, Harrison LR, pp. 640–672. Wingers, Lake Worth, FL. 8. Pulley T, Stannard AA: 1990, Tumors of the skin and soft tissues. In: Tumors in domestic animals, ed. Moulton JE, 3rd ed., pp. 23–87. University of California Press, Berkeley, CA. 9. Rose ME: 1981, Lymphatic system. In: Form and function in birds, ed. King AS, McLelland J, vol. 2, pp. 341–384. Academic Press, London, England. 10. Shingaki S, Suzuki I, Kobayashi T, Nakajima T: 1996, Predicting factors for distant metastases in head and neck carcinomas: an analysis of 103 patients with locoregional control. J Oral Maxillofac Surg 54:853–857. 11. Tagaki M, Kayano T, Yamamoto H, et al.: 1992, Causes of oral tongue cancer treatment failures. Analysis of autopsy cases. Cancer 69:1081–1087. 12. Yager JA, Scott DW: 1993, The skin and appendages. In: Pathology of domestic animals, ed. Jubb KVF, Kennedy PC, Palmer N, 4th ed., vol. 1, pp. 531–738. Academic Press, San Diego, CA.

Interhemispheric linkage of paleoclimate during the last glaciation

Abstract: Combined glacial geologic and palynologic data from the southern Lake District, Seno Reloncavi, and Isla Grande de Chiloe in middle latitudes (40°35’–42°25’S) of the Southern Hemisphere Andes suggest (1) that full-glacial or near-full-glacial climate conditions persisted from about 29,400 to 14,550 14C yr BP in late Llanquihue time, (2) that within this late Llanquihue interval mean summer temperature was depressed 6°–8°C compared to modern values during major glacier advances into the outer moraine belt at 29,400, 26,760, 22,295–22,570, and 14,550–14,805 14C yr BP, (3) that summer temperature depression was as great during early Llanquihue as during late Llanquihue time, (4) that climate deteriorated from warmer conditions during the early part to colder conditions during the later part of middle Llanquihue time, (5) that superimposed on long-term climate deterioration are Gramineae peaks on Isla Grande de Chiloe that represent cooling at 44,520–47,110 14C yr BP (T-11), 32,105–35,764 14C yr BP (T-9), 24,895–26,019 14C yr BP (T-7), 21,430–22,774 14C yr BP (T-5), and 13,040–15,200 14C yr BP (T-3), (6) that the initial phase of the glacial/interglacial transition of the last termination involved at least two major steps, one beginning at 14,600 14C yr BP and another at 12,700–13,000 14 C yr BP, and (7) that a late-glacial climate reversal of ≥2–3° C set in close to 12,200 14C yr BP, after an interval of near-interglacial warmth, and continued into Younger Dryas time. The late-glacial climate signal from the southern Chilean Lake District ties into that from proglacial Lago Mascardi in the nearby Argentine Andes, which shows rapid ice recession peaking at 12,400 14C yr BP, followed by a reversal of trend that culminated in Younger-Dryas-age glacier readvance at 11,400–10,200 14C yr BP. Many full- and late-glacial climate shifts in the southern Lake District match those from New Zealand at nearly the same Southern Hemisphere middle latitudes. At the last glacial maximum (LGM), snowline lowering relative to present-day values was nearly the same in the Southern Alps (875 m) and the Chilean Andes (1000 m). Particularly noteworthy are the new Younger-Dryas-age exposure dates of the Lake Misery moraines in Arthur's Pass in the Southern Alps. Moreover, pollen records from the Waikato lowlands on North Island show that a major vegetation shift at close to 14,700 14C yr BP marked the beginning of the last glacial/interglacial transition (Newnham et al. 1989). The synchronous and nearly uniform lowering of snowlines in Southern Hemisphere middle-latitude mountains compared with Northern Hemisphere values suggests global cooling of about the same magnitude in both hemispheres at the LGM. When compared with paleoclimate records from the North Atlantic region, the middle-latitude Southern Hemisphere terrestrial data imply interhemispheric symmetry of the structure and timing of the last glacial/interglacial transition. In both regions atmospheric warming pulses are implicated near the beginning of Oldest Dryas time (∼14,600 14C yr BP) and near the Oldest Dryas/Bolling transition (∼12,700–13,000 14 C yr BP). The second of these warming pulses was coincident with resumption of North Atlantic thermohaline circulation similar to that of the modern mode, with strong formation of Lower North Atlantic Deep Water in the Nordic Seas. In both regions, the maximum Bolling-age warmth was achieved at 12,200–12,500 14 C yr BP, and was followed by a reversal in climate trend. In the North Atlantic region, and possibly in middle latitudes of the Southern Hemisphere, this reversal culminated in a Younger-Dryas-age cold pulse. Although changes in ocean circulation can redistribute heat between the hemispheres, they cannot alone account either for the synchronous planetary cooling of the LGM or for the synchronous interhemispheric warming steps of the abrupt glacial-to-interglacial transition. Instead, the dominant interhemispheric climate linkage must feature a global atmospheric signal. The most likely source of this signal is a change in the greenhouse content of the atmosphere. We speculate that the Oldest Dryas warming pulse originated from an increase in atmospheric water-vapor production by half-precession forcing in the tropics. The major thermohaline switch near the Oldest Dryas/Bolling transition then couldhave triggered another increase in tropical water-vapor production to near-interglacial values.

Crab predation, waterborne cues, and inducible defenses in the blue mussel, mytilus edulis

Abstract: Inducible defenses are found in both terrestrial and aquatic organisms and appear to be a common defensive strategy of both sessile and mobile species. Here we report the presence of previously undescribed inducible defenses in marine mussels, a dominant member of temperate rocky intertidal communities. In the Gulf of Maine, estuarine shorelines with low water flow are characterized by high crab predation on the common blue mussel, Mytilus edulis, compared to nearby shore- lines with high water flow. Mussels at these high predation sites had thicker shells, relatively more shell mass, and were more tightly attached to the substrate than mussels at low predation sites. Field and laboratory experiments were used to test whether the between- site differences in these traits were the result of phenotypic plasticity. Mussels outplanted to high predation sites produced more byssal threads and attached more firmly to the substrate than did mussels outplanted to low predation sites. In the laboratory, thicker shells were induced by waterborne cues from both the common predator, Carcinus maenus, and damaged conspecifics, and these thicker shells were mechanically stronger than thinner, noninduced ones. Our results contribute to growing evidence that inducible defenses are a pervasive feature of intertidal assemblages. In addition to the bivalve example presented here, gastropods, barnacles, bryozoans, and seaweeds are also known to have inducible defenses. Phenotypic plasticity for defensive traits has likely evolved repeatedly in intertidal organisms and appears to play a major role in the dynamics of rocky intertidal communities.

An Econometric Analysis of the Costs of Sequestering Carbon in Forests

Abstract: The Kyoto Protocol and the U.S. Climate Change Plan recognize afforestation as a potential means of reducing atmospheric CO 2 concentrations. To examine the cost-effectiveness of afforestation, we use econometric land use models to estimate the marginal costs of carbon sequestration in Maine, South Carolina, and Wisconsin. Our findings include the following: (a) earlier studies of afforestation programs tend to underestimate carbon sequestration costs, (b) afforestation still appears to be a relatively low-cost approach to reducing CO 2 concentrations, (c) Wisconsin offers the lowest-cost opportunties for carbon sequestration, and (d) projected population changes have the largest effect on costs in South Carolina.

Ontology-driven geographic information systems

Abstract: Information integration is the combination of different types of information in a framework so that it can be queried, retrieved, and manipulated. Integration of geographic data has gained in importance because of the new possibilities arising from the interconnected world and the increasing availability of geographic information. Many times the need for information is so pressing that it does not matter if some details are lost, as long as integration is achieved. To integrate information across computerized information systems it is necessary first to have explicit formalizations of the mental concepts that people have about the real world. Furthermore, these concepts need to be grouped by communities in order to capture the basic agreements that exist within different communities. The explicit formalization of the mental models within a community is an ontology. This thesis introduces a framework for the integration of geographic information. We use ontologies as the foundation of this framework. By integrating ontologies that are linked to sources of geographic information we allow for the integration of geographic information based primarily on its meaning. Since the integration may occurs across different levels, we also create the basic mechanisms for enabling integration across different levels of detail. The use of an ontology, translated into an active, information-system component, leads Ontology-Driven Geographic Information Systems. The results of this thesis show that a model that incorporates hierarchies and roles has the potential to integrate more information than models that do not incorporate these concepts. We developed a methodology to evaluate the influence of the use of roles and of hierarchical structures for representing ontologies on the potential for information integration. The use of a hierarchical structure increases the potential for information integration. The use of roles also improves the potential for information integration, although to a much lesser extent than did the use of hierarchies. The combined effect of roles and hierarchies had a more positive effect in the potential for information integration than the use of roles alone or hierarchies alone. These three combinations (hierarchies, roles, roles and hiearchies) gave better results than the results using neither roles nor hierarchies.

Personal narrative, performance, performativity: Two or three things I know for sure

Abstract: The proliferation of personal narrative in contemporary culture and performance studies sparks both celebration and suspicion. This essay accesses and assesses current knowledge and issues about personal narrative by weaving three discourses: Dorothy Allison's performance piece Two or Three Things I Know for Sure, academic discourse, and personal narrative. From the conjoined perspectives of performance and performativity, personal narrative embodies cultural conflict about experience and identity. Performativity realizes the contextual and critical potential of the performance paradigm.

Algal Blooms on Coral Reefs: What Are the Causes?

Abstract: [Extract] The recent paper by Lapointe (1997) on the causes of algal blooms on coral reefs was presented as a test of the hypothesis that the reefs of Jamaica and southeast Florida had exceeded a threshold level of eutrophication that resulted in blooms of benthic algae. We offer this critique to evaluate the logic and efficacy of the tests presented by Lapointe (1997).

Is there competition between breast-feeding and maternal employment?

Abstract: Theory suggests that the decision to return to employment after childbirth and the decision to breast-feed may be jointly determined. We estimate models of simultaneous equations for two different aspects of the relationship between maternal employment and breast-feeding using 1993-1994 data from the U.S. Food and Drug Administration’s Infant Feeding Practices Study. We first explore the simultaneous duration of breast-feeding and work leave following childbirth. We find that the duration of leave from work significantly affects the duration of breast-feeding, but the effect of breast-feeding on work leave is insignificant. We also estimate models of the daily hours of work and breast-feedings at infant ages 3 months and 6 months postpartum. At both times, the intensity of work effort significantly affects the intensity of breast-feeding, but the reverse is generally not found. Competition clearly exists between work and breast-feeding for many women in our sample.

Ultraviolet‐B radiation stimulates shikimate pathway‐dependent accumulation of mycosporine‐like amino acids in the coral Stylophora pistillata despite decreases in its population of symbiotic dinoflagellates

Abstract: Colonies of Stylophora pistillata maintained for four years in indoor aquaria in the near absence of ultraviolet radiation (UVR) contained only small amounts (,5 nmol mg 21 protein) of 10 identified mycosporine-like amino acids (MAAs, which act as UV sunscreens), the largest number reported in any organism. The concentrations of most MAAs increased linearly or exponentially when colonies were exposed to ultraviolet-A (UVA) and ultraviolet-B (UVB) for 8hd 21 in the presence of photosynthetically active radiation (PAR). Total MAA concentration reached 174 nmol mg 21 protein after 30 d, with palythine and mycosporine-2 glycine constituting more than half of the final total. UVB specifically stimulated MAA accumulation: after 15 d, MAA levels in colonies exposed to PAR alone and to PAR and UVA did not differ (7 and 5 nmol MAA mg 21 protein, respectively), while those in colonies exposed to PAR and UVA 1 UVB were significantly higher (28 nmol mg 21 protein). Glyphosate, an inhibitor of the shikimate pathway, eliminated or reduced the UV-induced accumulation of most MAAs during 7 d of exposure, providing the first experimental evidence of their synthesis via this pathway in a coral symbiosis. Densities of zooxanthellae in colonies of S. pistillata, Acropora sp., and Seriatopora hystrix exposed to UVR for 15 d were only one-third of those in control colonies unexposed to UVR. This net decrease in the number of zooxanthellae in the corals (bleaching) occurred despite UV-stimulated increases in algal cytokinesis and in the host cell-specific density of zooxanthellae in hospite, increases that apparently destabilized the symbiosis and caused expulsion of the zooxanthellae.

Phylogeny of Rubus (rosaceae) based on nuclear ribosomal DNA internal transcribed spacer region sequences.

Abstract: We used nuclear ribosomal DNA internal transcribed spacer region (ITS 1 2 5.8S 2 ITS 2; ITS) sequences to generate the first phylogeny of Rubus based on a large, molecular data set. We sampled 57 taxa including 20 species of subgenus Rubus (blackberries), one to seven species from each of the remaining 11 subgenera, and the monotypic and closely related Dalibarda .I nRubus, ITS sequences are most informative among subgenera, and variability is low between closely related species. Parsimony analysis indicates that Rubus plus Dalibarda form a strongly supported clade, and D. repens may nest within Rubus. Of the subgenera with more than one species sampled, only subgenus Orobatus appears monophyletic. Three large clades are strongly supported: one contains all sampled species of nine of the 12 subgenera; another includes extreme Southern Hemisphere species of subgenera Comaropsis, Dalibarda, and Lampobatus; and a third clade consists of subgenus Rubus plus R. alpinus of subgenus Lampobatus. Rubus ursinus appears to be a hybrid between a close relative of R. macraei (subgenus Idaeobatus, raspberries) and an unidentified subgenus Rubus species. ITS sequences are generally consistent with biogeography and ploidy, but traditionally important morphological characters, such as stem armature and leaf type, appear to have limited phylogenetic value in Rubus.

Physical and psychosocial correlates of head and neck cancer: a review of the literature.

Abstract: This article reviews recent literature on the physical and psychosocial correlates of head and neck cancer, with a focus on quality-of-life issues, rehabilitation outcomes, and changes in the literature from the previous decade. These studies have shown that head and neck cancer has an enormous impact on the quality of life of patients. The most important physical symptoms are speech problems, dry mouth and throat, and swallowing problems. Pain is also frequently reported. Disturbances in psychosocial functioning and psychological distress are reported by a considerable number of patients; worry, anxiety, mood disorder, fatigue, and depression are the main symptoms. Cancer of the head and neck has a negative effect on social, recreational, and sexual functioning. Despite a growing number of longitudinal studies, little is known about the rehabilitation outcomes over a longer period of time. Future research is necessary to form a consensus about the further development and use of specific instruments to study patients with cancer of the head and neck, to conduct more prospective studies, and to develop programs that are aimed at maximizing rehabilitation outcomes and evaluate these programs with randomized designs.

Principles and applications of BPCS steganography

Abstract: Steganography is a technique to hide secret information in some other data (we call it a vessel) without leaving any apparent evidence of data alteration. All of the traditional steganographic techniques have limited information-hiding capacity. They can hide only 10% (or less) of the data amounts of the vessel. This is because the principle of those techniques was either to replace a special part of the frequency components of the vessel image, or to replace all the least significant bits of a multivalued image with the secret information. Our new steganography uses an image as the vessel data, and we embed secret information in the bit-planes of the vessel. This technique makes use of the characteristics of the human vision system whereby a human cannot perceive any shape information in a very complicated binary pattern. We can replace all of the noise-like regions in the bit-planes of the vessel image with secret data without deteriorating the image quality. We termed our steganography BPCS-Steganography, which stands for Bit-Plane Complexity Segmentation Steganography. We made an experimental system to investigate this technique in depth. The merits of BPCS-Steganography found by the experiments are as follows. 1. The information hiding capacity of a true color image is around 50%. 2. A sharpening operation on the dummy image increases the embedding capacity quite a bit. 3. Canonical Gray coded bit planes are more suitable for BPCS-Steganography than the standard binary bit planes. 4. Randomization of the secret data by a compression operation makes the embedded data more intangible. 5. Customization of a BPCS-Steganography program for each user is easy. It further protects against eavesdropping on the embedded information.

Abrupt vegetation and climate changes during the last glacial maximum and last termination in the chilean lake district: a case study from canal de la puntilla (41¡s)

Abstract: Multiple overlapping and replicate pollen stratigraphies from Canal de la Puntilla (40°57'09S, 72°54'18W, 120 m elevation) reveal that a Nothofagus dombeyi-type parkland occupied the Valle Central of the Chilean Lake District during the portion of the Last Glacial Maximum between 20,200 and about 14,600 14 C yr BP. Dominating this landscape was Nothofagus dombeyi-type and Gramineae, accompanied by taxa commonly found today in Subantarctic environments and above the Andean tree-line in the Lake District (Perezia-type, Valeriana, and Huperzia selago), along with cushion bog taxa characteristic of Magellanic Moorlands (Donatia fascicularis and Astelia pumila). Within this open landscape Nothofagus dombeyi-type expanded between 20,200 and 15,800 14 C yr BP, interrupted by a brief reversal between 19,200 and 18,800 14 C yr BP and followed by a prominent increase in Gramineae pollen between 15.800 and about 14,600 14 C yr BP. A major rise of Nothofagus dombeyi-type began at about 14,600 14 C yr BP, followed by decline in non-arboreal taxa and a remarkable expansion of North Patagonian Rain Forest taxa in pulses centered at 14,200 and 13,000 14 C yr BP. Podocarpus nubigena expanded between 12,200 and 9800 14 C yr BP, along with increases in Misodendrum and Maytenus disticha-type between 11,000 and 9800 14 C yr BP. Paleovegetation records suggest that mean annual temperature was 6-7°C colder than at present during the coldest episodes between 20,200 and about 14,600 14 C yr BP, with twice the modem annual precipitation between 20,200 and 13,000 14 C yr BP, suggesting a northward shift and intensification of westerly stormtracks. Slight climate warming occurred between 20,200 and 15,800 14 C yr BP, interrupted by cooling events at 19,200 and 15,800 14 C yr BP. The initial warming of the last termination started at 14,600 14 C yr BP, followed by wanning pulses at 14,200 and 13,000 14 C yr BP. These events brought glacial conditions to a cool-temperate climate, slightly cooler and welter than modern climate, accounting for a total temperature recovery of ≥5°C by about 13,000 14 C yr BP. A general reversal in trend is inferred with cooling events at 12,200 and 11,000 14 C yr BP.

Geomorphology, Stratigraphy, and Radiocarbon Chronology of LlanquihueDrift in the Area of the Southern Lake District, Seno Reloncaví, and Isla Grande de Chiloé, Chile

Abstract: Glacial geomorphologic features composed of (or cut into) Llanquihue drift delineate former Andean piedmont glaciers in in the region of the southern Chilean Lake District,Seno Reloncavi, Golfo de Ancud, and northern Golfo Corcovado during the last glaciation. These landforms include extensive moraine belts, main and subsidiary outwash plains, kame terraces, and meltwater spillways. Nt Numerous radiocarbon dates document Andean ice advances into the moraine belts during the last glacial maximum (LGM) at 29,363-29,385 14 C yr BP, 26,797 14 C yr BP, 22,295-22,570 14 C yr BP, and 14,805-14,869 14 C yr BP.Advances may also have culminated at close to 21,000 14 C yr BP, shortly before 17,800 14 C yr BP, and shortly before 15,730 14 C yr BP. The maximum at 22,295-22,567 14 C yr BP was probably the most extensive of the LGM in the northern part of the field area, whereas that at 14,805-14,869 14 C yr BP was the most extensive in the southern part. Snowline depression during these maxima was about 1000 m. Andean piedmont glaciers did not advance into the outer Llanquihue moraine belts during the portion of middle Llanquihue time between 29,385 14 C yr BP and more than 39,660 14 C yr BP. In the southern part of the field area, the Golfo de Ancud lobe, as well the Golfo Corcovado lobe, achieved a maximum at the outermost Llanquihue moraine prior to 49,892 14 C yr BP. Pollen analysis of the Taiquemo mire,which is located on this moraine, suggests that the old Llanquihue advance probably corresponds to the time of marine isotope stage 4. The implication is that Andean snowline was then depressed as much as during the LGM. A Llanquihue-age glacier expansion into the outer moraine belts also occurred more than about 40,000 14 C yr BP for the Lago Llanquihue piedmont glacier.

EVOLUTION OF THE FUCACEAE (PHAEOPHYCEAE) INFERRED FROM nrDNA‐ITS

Abstract: Sequences of the internal transcribed spacer region (ITS-1, 5.8S, and ITS-2) of nuclear ribosomal DNA were obtained from 16 species representing all six genera of Fucaceae (Ascophyllum, Fucus, Hesperophycus, Pelvetia, Pelvetiopsis, and Xiphophora) plus one outgroup (Hormosira). Parsimony analysis indicated that the family Fucaceae is monophyletic and that the northern hemisphere taxa are highly divergent from the only southern hemisphere genus, Xiphophora. The genus Pelvetia is not monophyletic because the European P. canaliculata is more closely related to Fucus, Hesperophycus, and Pelvetiopsis than to other Pelvetia species. We establish Silvetia, gen. nov. and transfer the 3 Pacific species of Pelvetia to the new genus. Fucus is monophyletic and not ancestral in the Fucaceae. The ITS sequences identified two strongly supported lineages within Fucus, one with F. serratus sister to the clade containing F. gardneri, F. distichus, and F. evanescens and a second including F. vesiculosus, F. spiralis, F. ceranoides, and F. virsoides. The ITS was not useful for resolving relationships within each of these clusters and between populations of F. vesiculosus. Within-individual variation in ITS sequences is high in Fucus, a derived genus, compared to Ascophyllum, a more ancestral genus. Mapping of the two characters that form the basis of Powell’s model for speciation in the Fucaceae showed that 1) number of eggs per oogonium has not followed a gradual reduction and that 2) monoecy/dioecy has changed several times during evolution of this family.

Statistical mechanical simulation of polymeric DNA melting with MELTSIM.

Abstract: MOTIVATION MELTSIM is a windows-based statistical mechanical program for simulating melting curves of DNAs of known sequence and genomic dimensions under different conditions of ionic strength with great accuracy. The program is useful for mapping variations of base compositions of sequences, conducting studies of denaturation, establishing appropriate conditions for hybridization and renaturation, determinations of sequence complexity, and sequence divergence. RESULTS Good agreement is achieved between experimental and calculated melting curves of plasmid, bacterial, yeast and human DNAs. Denaturation maps that accompany the calculated curves indicate non-coding regions have a significantly lower (G+C) composition than coding regions in all species examined. Curves of partially sequenced human DNA suggest the current database may be heavily biased with coding regions, and excluding large (A+T)-rich elements. AVAILABILITY MELTSIM 1.0 is available at: //www.uml.edu/Dept/Chem/UMLBIC/Apps/MEL TSIM/MELTSIM-1.0-Win/meltsim. zip. Melting curve plots in this paper were made with GNUPLOT 3.5, available at: http://www.cs.dartmouth.edu/gnuplot_inf o.html Contact : blake@maine.maine.edu;

Photodecomposition of the Carbamate Pesticide Carbofuran: Kinetics and the Influence of Dissolved Organic Matter

Abstract: This study examined the photodecomposition of carbofuran, a carbamate pesticide with high oral toxicity. Rate constants are measured for the pesticide in aqueous solution and in the presence of various samples of dissolved organic matter (DOM). Kinetic experiments are monitored with HPLC, while reaction products are determined using HPLC, GC−MS, and 1H NMR: mechanisms are proposed for the first three steps of the reaction. It was found that the photodecomposition proceeds via first-order reaction kinetics and that the presence of various DOM samples inhibits the photolysis reaction of carbofuran. This phenomenon can be correlated to the magnitude of the binding interaction between carbofuran and DOM. Finally, techniques such as GC−MS and 1H NMR are used to identify the photodecomposition products. The first three steps of the reaction are defined. In the first step of the reaction, the carbamate group is cleaved from the molecule. The furan moiety is opened in the second step producing a substituted cate...

Modeling Land Use Decisions with Aggregate Data

Abstract: In this article, we develop land use models to study the impact of changes in decision variables on soil erosion or other environmental outcomes. From an underlying behavioral model, we use maximum entropy to recover a parametric model of county-level land use shares as a function of decision variables such as output prices, input costs, and land quality. The statistical model may be extended to estimate subcounty land use shares and to incorporate data from federal land use surveys. We use the procedure to analyze the impact of changes in livestock inventories on soil erosion rates in three Iowa counties.

Transitions in the mid-Holocene

Abstract: Between about 8000 and 3000 years ago, climate worldwide underwent substantial changes. At the same time, human cultures experienced a period of substantial progress toward more complex societies, as exemplified by the first temple mounds in South America, the Egyptian pyramids, and the rise and fall of civilizations in East Asia. Archeologists and paleoclimotologists alike are now investigating possible causal connections between these simultaneous developments and are finding a complex pattern of cultural responses to climatic change.

De Novo Synthesis of 4,5-Dimethoxycatechol and 2,5-Dimethoxyhydroquinone by the Brown Rot Fungus Gloeophyllum trabeum†

Abstract: The new dimethoxycatechol 4,5-dimethoxy-1,2-benzenediol (DMC) and the new dimethoxyhydroquinone 2,5-dimethoxy-1,4-benzenediol (DMH) were isolated from stationary cultures of the brown rot fungus Gloeophyllum trabeum growing on a glucose mineral medium protected from light. The structure was elucidated by gas chromatography-mass spectrometry through comparison to a synthetic standard. Further confirmation was obtained by forming a dimethoxyoxazole derivative by condensation of DMC with methylene chloride and through examination of methylated derivatives. DMC and DMH may serve as ferric chelators, oxygen-reducing agents, and redox-cycling molecules, which would include functioning as electron transport carriers to Fenton’s reactions. Thus, they appear to be important components of the brown rot decay system of the fungus.

Modeling Land Use Decisions with Aggregate Data

Abstract: In this article, we develop land use models to study the impact of changes in decision variables on soil erosion or other environmental outcomes. From an underlying behavioral model, we use maximum entropy to recover a parametric model of county-level land use shares as a function of decision variables such as output prices, input costs, and land quality. The statistical model may be extended to estimate subcounty land use shares and to incorporate data from federal land use surveys. We use the procedure to analyze the impact of changes in livestock inventories on soil erosion rates in three Iowa counties.