Mean Maximum Depth Research Articles

Agronomic-meteorological model for weather forecasting to predict the rainfall using machine learning techniques

Weather forecasting is essential and a challenging area for predicting rainfall. As the climatic conditions are changing dramatically, accurate prediction of atmospheric conditions is difficult. Various machine learning techniques like support vector machine (SVM) classification and regression can be applied to predict rainfall using various parameters like mean temperature, wind speed, mean dew point, minimum and maximum temperature, precipitation level, snow depth and wind gust. The proposed model for weather forecasting uses support vector machine classification and regression. This technique can be applied on weather dataset in order to predict accurate precipitation which is most useful for agricultural purpose. These results can be effectively used by agricultural sector. This useful information is given to the farmer for increasing their agricultural growth which leads to better productivity.

Agronomic-meteorological model for weather forecasting to predict the rainfall using machine learning techniques

Weather forecasting is essential and a challenging area for predicting rainfall. As the climatic conditions are changing dramatically, accurate prediction of atmospheric conditions is difficult. Various machine learning techniques like support vector machine (SVM) classification and regression can be applied to predict rainfall using various parameters like mean temperature, wind speed, mean dew point, minimum and maximum temperature, precipitation level, snow depth and wind gust. The proposed model for weather forecasting uses support vector machine classification and regression. This technique can be applied on weather dataset in order to predict accurate precipitation which is most useful for agricultural purpose. These results can be effectively used by agricultural sector. This useful information is given to the farmer for increasing their agricultural growth which leads to better productivity.

Influence of erbium, chromium-doped: Yttrium scandium-gallium-garnet laser etching and traditional etching systems on depth of resin penetration in enamel: A confocal laser scanning electron microscope study.

Objective:This study was performed to assess the resin tag length penetration in enamel surface after bonding of brackets to identify which system was most efficient.Methodology:Our study was based on a more robust confocal microscopy for visualizing the resin tags in enamel. Totally, 100 extracted human first and second premolars have been selected for this study and were randomly divided into ten groups of 10 teeth each. In Group 1, the buccal enamel surface was etched with 37% phosphoric acid (3M ESPE), Group 2 with 37% phosphoric (Ultradent). In Groups 5, 6, and 7, erbium, chromium-doped: Yttrium scandium-gallium-garnet (Er, Cr: YSGG) laser (Biolase) was used for etching the using following specifications: Group 5 (1.5 W/20 Hz, 15 s), Group 6 (2 W/10 Hz, 15 s), and Group 7 (2 W/20 Hz, 15 s). In Groups 8, 9, and 10, Er, Cr: YSGG laser (Biolase) using same specifications and additional to this step, conventional etching on the buccal enamel surface was etched with 37% (3M ESPE) after laser etching. In Groups 1, 5, 6, 7, 8, 9, and 10 3M Unitek Transbond XT primer was mixed with Rhodamine B dye (Sigma-Aldrich, Germany) to etched surface and then cured for 20 s. In Group 2, Ultradents bonding agent was mixed with Rhodamine B. In Group 3, 3M Unitek Transbond PLUS, Monrovia, USA, which was mixed with Rhodamine B dye (Sigma-Aldrich, Germany). Group 4, with self-etching primer (Ultradent-Peak SE, USA) was mixed with Rhodamine B dye (Sigma-Aldrich, Germany). Later (3M Unitek, Transbond XT, Monrovia USA) [Figure 1] was used to bond the modified Begg brackets (T. P. Orthodontics) in Groups 1, 3, 5, 6, 7, 8, 9, and 10. In Groups 2, 4 Ultradent-Peak LC Bond was used to bond the modified brackets. After curing brackets were debonded, and enamel depth penetration was assessed using confocal laser scanning microscope.Results:Group J had a mean maximum depth of penetration of 100.876 μm, and Group D was the least having a maximum value of 44.254 μm.Conclusions:Laser alone groups had comparable depths of penetration to that of self-etching groups but much lower than conventional acid etched groups.

Fish Assemblages of Floodplain Lakes in the Ohio River Basin

We sampled fish assemblages in 41 floodplain lakes in the Ohio River Basin in the summer of 2012. We collected 2427 individual fishes in 70 species. Mean abundance of individuals at sites was 66, and mean species richness per site was 8.1. We used two multivariate procedures to predict fish-assemblage variation from habitat and environmental variables: an indirect gradient approach (reciprocal averaging [RA]) and a direct gradient approach (canonical correspondence analysis [CCA]). When we applied a forward selection process in the CCA, the habitat and environmental variables that contributed significantly to explaining variation in fishes were mean elevation, latitude, maximum depth, conductivity, longitude, dissolved oxygen, cobble and sand substrates, and lake-surface area. RA provided different results that suggested the presence of additional environmental gradients we did not quantify. Our results show that floodplain lakes in the Ohio River basin contain high species richness and are important habitats to conserve because they have the potential to act as source pools for river fish populations.

Proximity to ice fields and lake depth as modulators of paleoclimate records: a regional study from southwest Yukon, Canada

Pronounced climate warming during the past century has been well documented in high-latitude regions. Nonetheless, considerable heterogeneity exists in northern climate trends. We examined the roles of cryospheric landscape and lake depth in modulating the rate and magnitude of local climate responses through a paleolimnological study of lakes from southwest Yukon, Canada. By sampling lakes at varying distances from the Wrangell-St. Elias ice fields, we hypothesized that, for lakes of similar maximum depth, sites closest to the ice fields would be relatively complacent in terms of their chironomid and diatom assemblage changes over the past ~200 years. This hypothesis is based on the moderating effect of the glaciers on local climate, which would be most pronounced in the lakes nearest to the ice fields. However, given the known ecological differences between deep and shallow lakes, we further predicted that, for a given distance from the ice fields, a sediment record from a shallower lake would show the greatest change in stratigraphic subfossil assemblages. Because of the complicated shape of the ice fields, we applied the longitude for each site (which decreases from west to east) to approximate the proximity of our study lakes to the ice fields. Consistent with our predictions, we observed a space-transgressive pattern in the chironomid assemblage turnover that was associated with their proximity to the ice fields (r = −0.75, P = 0.034, n = 8) across lakes of similar depth (mean maximum depth ± 1, SE = 18.1 ± 2.6 m). Considering a broader network of lakes that represented a greater range in maximum depth (4.9–29 m), we found that differences in subfossil chironomid assemblages between the modern and ca. AD 1800 sediment layers were strongly related to lake depth (r = −0.77, P < 0.001, n = 15), but failed to detect a significant relationship with latitude or longitude (i.e. our proxy for proximity to the ice fields). Similarly, our comparative high-resolution analyses of two lakes with distinct lake morphometries, but similar proximities to the ice fields, demonstrated the predicted contrasting pattern: we observed pronounced post-1880 changes in the biotic assemblages in the shallow lake and a muted and delayed response (i.e. ~1970s) in the deeper lake. Our findings confirm that cryospheric landscape features can strongly modulate regional climate. Furthermore, our work shows that investigators need to be conscious of how climate change affects the structure and functioning of lakes of different typologies, which influences the way in which paleoclimate signals are recorded and interpreted.

Colonization of the deep sea by fishes

Analysis of maximum depth of occurrence of 11 952 marine fish species shows a global decrease in species number (N) with depth (x; m): log10N = −0·000422x + 3·610000 (r2 = 0·948). The rate of decrease is close to global estimates for change in pelagic and benthic biomass with depth (−0·000430), indicating that species richness of fishes may be limited by food energy availability in the deep sea. The slopes for the Classes Myxini (−0·000488) and Actinopterygii (−0·000413) follow this trend but Chondrichthyes decrease more rapidly (−0·000731) implying deficiency in ability to colonize the deep sea. Maximum depths attained are 2743, 4156 and 8370 m for Myxini, Chondrichthyes and Actinopterygii, respectively. Endemic species occur in abundance at 7–7800 m depth in hadal trenches but appear to be absent from the deepest parts of the oceans, >9000 m deep. There have been six global oceanic anoxic events (OAE) since the origin of the major fish taxa in the Devonian c. 400 million years ago (mya). Colonization of the deep sea has taken place largely since the most recent OAE in the Cretaceous 94 mya when the Atlantic Ocean opened up. Patterns of global oceanic circulation oxygenating the deep ocean basins became established coinciding with a period of teleost diversification and appearance of the Acanthopterygii. Within the Actinopterygii, there is a trend for greater invasion of the deep sea by the lower taxa in accordance with the Andriashev paradigm. Here, 31 deep-sea families of Actinopterygii were identified with mean maximum depth >1000 m and with >10 species. Those with most of their constituent species living shallower than 1000 m are proposed as invasive, with extinctions in the deep being continuously balanced by export of species from shallow seas. Specialized families with most species deeper than 1000 m are termed deep-sea endemics in this study; these appear to persist in the deep by virtue of global distribution enabling recovery from regional extinctions. Deep-sea invasive families such as Ophidiidae and Liparidae make the greatest contribution to fish fauna at depths >6000 m.

Confocal laser scanning microscopic investigation of ultrasonic, sonic, and rotary sealer placement techniques

Background:Sealers are used to attain an impervious seal between the core material and root canal walls.Aim:To compare the depth and percentage of sealer penetration with three different placement techniques using confocal laser scanning microscopy as the evaluative tool.Materials and Methods:Root canals of 30 single-rooted teeth were prepared to a size of F3 and AH plus sealer with Rhodamine B was applied with Ultlrasonic file (Gr-1), lentulospiral (Gr-2), and Endoactivator (Gr-3). Canals were obturated with gutta-percha. The roots were sectioned at the 3 and 6-mm levels from the apical foramen and were examined on a confocal microscope.Results:A statistical significant differences among Gr-1, Gr-2, and Gr-3 were found at the 3 and 6-mm level (P < 0.05; ANOVA-Tukey tests) for the depth and percentage of sealer penetration except for Gr-1 and Gr-2 at 3-mm level. Gr-1 showed maximum mean depth of penetration (810 μm) and maximum mean percentage of sealer penetration (64.5) while Gr-3 showed minimum mean depth of penetration (112.7 μm) and minimum mean percentage of sealer penetration (26.7).Conclusion:Depth and percentage of penetration of sealer is influenced by the type of placement technique and by the root canal level with penetration decreasing apically.

Classification and behavior of free-ranging Weddell seal dives based on three-dimensional movements and video-recorded observations

The goal of this study was to classify free-ranging (FR) dives of Weddell seals (Leptonychotes weddellii) and to compare them to isolated hole (IH) dives. Classification and comparisons were based on 58 descriptors for three-dimensional dive paths computed from data obtained by attaching video and data recorders to the backs of 12 adult Weddell seals that were free-ranging in eastern McMurdo Sound, Antarctica. We then inferred behavioral functions for the dive classes based on video-recorded observations. Three of the four dive types previously identified from seals diving at an IH occurred in FR seals. Although there were differences associated with location, Types 1, 2 and 3 dives clustered in a similar pattern in the discriminant analysis for FR and IH dives. Most prey (79%) captures occurred during Type 1 dives, and the primary (99%) prey was Antarctic silverfish (Pleuragramma antarcticum). Type 1 dives were the deepest (mean maximum depth 324–378m), longest in duration (15.0–27.0min), covered the greatest total distance (1470–2197m), and had the steepest dive angles (descents: −30°; ascents: +27°). Types 2 and 3 dives formed a continuum from short duration (3.6–7.5min), shallow (mean maximum depth 30–66m) dives that were close to the ice hole (farpoint distance 75–130m) and often involved aggressive interactions with other seals for breathing opportunities (Type 2) to progressively longer (7.9–17.2min), deeper (mean maximum depth 81–143m) dives that covered greater total distances (878–1194m) and were associated with transiting between holes, exploring and occasionally foraging (Type 3). Very long distance Type 4 exploratory dives that were identified in the IH study were completely absent in FR seals.

Habitat use by a freshwater dolphin in the low‐water season

ABSTRACT Many river dolphin populations are most vulnerable during the low‐water season when habitat is limited. Indus River dolphin habitat selection in the dry season was investigated using Generalized Linear Models of dolphin distribution and abundance in relation to physical features of river geomorphology and channel geometry in cross‐section. Dolphins selected locations in the river with significantly greater mean depth, maximum depth, cross‐sectional area, and hydraulic radius, and significantly narrower river width and a lower degree of braiding than areas where dolphins were absent. They were also recorded with higher frequency at river constrictions and at confluences. Channel cross‐sectional area was the most important factor affecting dolphin presence and abundance, with the area of water below 1 m in depth exerting the greatest influence. Indus dolphins avoided channels with small cross‐sectional area (&lt;700 m2), presumably owing to the risk of entrapment and reduced foraging opportunities. Channel geometry had a greater ability to explain dolphin distribution than river geomorphology; however, both analyses indicated similar types of habitat selection. The dolphin–habitat relationships identified in the river geomorphology analysis were scale‐dependent, indicating that dolphin distribution is driven by the occurrence of discrete small‐scale features, such as confluences and constrictions, as well as by broader‐scale habitat complexes. There are numerous plans to impound or extract more water from the Indus River system. If low‐water season flows are allowed to decrease further, the amount of deeper habitat will decline, there may be insufficient patches of suitable habitat to support the dolphin population through the low‐water season, and dolphins may become isolated within deeper river sections, unable or unwilling to traverse through shallows between favourable patches of habitat. Copyright © 2012 John Wiley &amp; Sons, Ltd.

Spiral Enteroscopy: A Novel Method of Enteroscopy for Evaluation and Treatment of Obscure Gastrointestinal Bleeding Caused by Small Bowel Lesions

Obscure gastrointestinal (GI) bleeding most commonly originates in the small bowel. Up to almost 80% of obscure GI bleeding sources are not within the reach of a conventional endoscope or colonoscope hence the need of enteroscopy. Spirus enteroscopy as a new tool for both diagnosis and therapeutic interventions on the small bowel is currently being evaluated for its usefulness on obscure GI bleeding patients. This prospective cohort study included 78 patients who underwent spiral enteroscopy for evaluation of obscure GI bleeding between February 2008 and March 2010 at our institution. Twenty-seven patients with occult-obscure GI bleeding and 51 patients with overt-obscure GI bleeding were studied. Total of 78 patients underwent total of 82 spiral enteroscopies (second spiral enteroscopy was repeated in some patients with negative first spiral enteroscopy) with mean (±SD) maximum depth of insertion of 226 (±80.97). Spiral enteroscopies were able to identify bleeding sources in 48 patients (61.54%). Small bowel lesions accounted for the source of bleeding in 39 patients (81.25%). For total of 82 procedures, the small bowel lesions were arteriovenous malformation (31, 37.8%), diverticulum (6, 7.32%), tumor (2, 2.44%), erosion (1, 1.22%), and ulcer (1, 1.22%). Forty-five patients underwent endoscopic interventions which included biopsies, argon plasma coagulation and bipolar electrocoagulation. There were no procedure related adverse events. In patients with obscure GI bleeding, spiral enteroscopy is safe and effective in diagnosis and has an important role in treatment caused by small bowel lesions.

Dynamics of Root Growth and Distribution in Maize from the Black Soil Region of NE China

Root growth is related to its water and mineral uptake. The structure and architecture of the root system is influenced by soil properties. Better understanding of root architecture and growth dynamics of maize grown on black soil may lead to more efficient use of applied nutrients and water by maize. Maize (Zea mays L.), cultivar Yedan 13, was grown in a black soil field in large root boxes in 2007. Plants were regularly sampled and the following data were recorded: number of emerged roots per phytomer, mean length and maximal length of axile root per phytomer, maximum rooting depth of axile root per phytomer, and angle of axile root per phytomer by excavation methods. The distribution dynamics of root dry weight at different black soil depths, and vertical and horizontal distribution in large root boxes were measured. There were more axile roots on the upper phytomers than on lower phytomers. The number of roots on phytomers P8, P9 and P10 were 15.71%?24.82%, and 25.86% of total number of per plant, respectively. Angles of the axile roots on lower phytomers were larger than those on upper phytomers. The angle of the axile root on P2 was the largest (81.51°), followed by P4 (69.33°), P3 (56.9°), and P5 (56.06°). The angles on phytomers from P6 to P10 were smaller, ranging from 30.13-40.72°. Mean length, maximal length, and maximum rooting depth of axile root on each phytomer all increased with day after seeding (DAS). Mean length, maximal length, and maximum rooting depth of axile roots on lower phytomers were larger than those on upper phytomers. Mean length, maximal length and maximum rooting depth of axile roots on P3 were the largest (2.37 m, 2.92 m and 2.12 m at 90 DAS, respectively). Root dry weight in each soil layer increased with DAS; there was a rapid increase from 50 to 90 DAS. About 80 % of root dry weight was in the soil above 40 cm. The general trend of percentage of dry weight in total dry weight per plant decreased as the distance from the plant increased. Over 78 % of root dry weight in total dry weight per plant was within 20 cm in the horizontal direction from the plant, and less than 6% was in the 40 cm to 60 cm zone in the horizontal direction from the plant.

Hydraulic Complexity Metrics for Evaluating In-Stream Brook Trout Habitat

A two-dimensional hydraulic model (River2D) was used to investigate the significance of flow complexity on habitat preferences of brook trout (Salvelinus fontinalis) in the high-gradient Staunton River in Shenandoah National Park, Virginia. Two 100-m reaches were modeled where detailed brook trout surveys (10–30-m resolution) have been conducted annually since 1997. Spatial hydraulic complexity metrics including area-weighted circulation and kinetic energy gradients (KEG) were calculated based on modeled velocity distributions. These metrics were compared to fish density in individual habitat complexes (10–30-m subreaches) to evaluate relationships between fish location and average flow complexity. In addition, the fish density was compared to additional habitat variables including percent cascade (CS), pool (PL) and riffle, and in-stream (ISCN) and riparian cover. There were negative correlations between modeled mean velocity (VEL) and maximum depth (MAXD) and fish density; however, there were no statistically significant correlations between KEGs or area-weighted circulation and fish density. Fish density was negatively correlated to ISCN and positively correlated to the percent of the channel dominated by protruding boulders (BD) and CS. The structural complexity of cascade habitat and areas with protruding boulders creates complex flow patterns indicating that flow complexity plays an important role in brook trout habitat preferences at the local scale. Linear discriminate analysis was used to further investigate the relationships between habitat variables and fish density. Using backward stepwise variable selection, the final explanatory model contained the BD, ISCN, MAXD, PL, and VEL variables. These observations indicate that at a coarse spatial scale hydraulic complexity may be an important component in fish habitat preferences; however, other habitat variables cannot be ignored and the hydraulic complexity metrics calculated using 2D modeling results were not explanatory. While spatial hydraulic complexity metrics provide quantifiable measures for evaluating stream restoration project impacts on in-stream habitat quality, the relationships between fish density and hydraulic complexity were not straightforward. This is likely due in part to modeling limitations in this high-gradient complex stream. Further research is needed at a range of spatial scales, stream types, and fish species to fully investigate the use of hydraulic complexity metrics to quantify in-stream habitat.

Diel foraging behavior of gravid leatherback sea turtles in deep waters of the Caribbean Sea

It is generally assumed that leatherback turtles (Dermochelys coriacea), like other species of sea turtle, do not feed while offshore from nesting beaches, and rely instead on fat reserves to fuel reproductive activities. Recent studies, however, provide evidence that leatherbacks may forage during the internesting interval while offshore in the Western Atlantic Ocean and Caribbean Sea. Bio-logging technology was used to investigate the foraging behavior of female leatherback turtles at St Croix, US Virgin Islands. Leatherback gastrointestinal tract temperatures (T(GT)) were analyzed for sudden fluctuations indicative of ingestions, and laboratory ingestion simulations were used to characterize temperature fluctuations associated with ingestion of prey versus seawater. Dive patterns associated with prey ingestion were characterized and the proportion of prey ingestion during the day (05:00-18:59 h) and night (19:00-04:59 h) were compared. A combined total of 111 prey ingestions for seven leatherback turtles were documented during the internesting interval. The number of prey ingestions ranged from six to 48 for individual turtles, and the majority (87.4%) of these events occurred during the daytime. Prey ingestions were most frequently associated with V-shaped dives, and the mean (±1 s.d.) maximum dive depth with prey ingestion ranged from 154±51 to 232±101 m for individual turtles. Although leatherbacks were found to opportunistically feed during the internesting interval, the low prey ingestion rates indicate that energy reserves acquired prior to the breeding season are critical for successful reproduction by leatherbacks from the St Croix, USVI nesting population.

Vertical stratification of physical, chemical and biological components in two saline lakes Shira and Shunet (South Siberia, Russia)

A feature of meromictic lakes is that several physicochemical and biological gradients affect the vertical distribution of different organisms. The vertical stratification of physical, chemical and biological components in saline, fishless meromictic lakes Shira and Shunet (Siberia, Russia) is quite different mainly because both mean depth and maximum depth of lakes differ as well as their salinity levels differ. The chemocline of the Lake Shira, as in many meromictic lakes, is inhabited by bacterial community consisting of purple sulphur and heterotrophic bacteria. As the depth of the chemocline is variable, the bacterial community does not attain high densities. The mixolimnion in Lake Shira, which is thermally stratified in summer, also creates different habitat for various species. The distribution of phytoplankton is non-uniform with its biomass peak in the metalimnion. The distribution of zooplankton is also heterogeneous with rotifers and juvenile copepods inhabiting the warmer epilimnion and older copepods found in the cold but oxic hypolimnion. The amphipod Gammarus lacustris which can be assigned to the higher trophic link in the fishless lake’s ecosystem, such as Lake Shira, is also distributed non-uniformly, with its peak density generally observed in the thermocline region. The chemocline in Lake Shunet is located at the depth of 5 m, and unlike in Lake Shira, due to a sharp salinity gradient between the mixolimnion and monimolimnion, this depth is very stable. The mixolimnion in Lake Shunet is relatively shallow and the chemocline is inhabited by (1) an extremely dense bacterial community; (2) a population of Cryptomonas sp.; and (3) ciliate community comprising several species. As the mixolimnion of Lake Shunet is not thermally stratified for long period, the phytoplankton and zooplankton populations are not vertically stratified. The gammarids, however, tend to concentrate in a narrow layer located 1–2 m above the chemocline. We believe that in addition to vertical inhomogeneities of both physicochemical parameters, biological and physical factors also play a role in maintaining these inhomogeneities. We conclude that the stratified distributions of the major food web components will have several implications for ecosystem structure and dynamics. Trophic interactions as well as mass and energy flows can be significantly impacted by such heterogeneous distributions. Species spatially separated even by relatively short distances, say a few centimetres will not directly compete. Importantly, we demonstrate that not only bacteria, phytoflagellates and ciliate tend to concentrate in thin layers but also larger-sized species such Gammarus (amphipods) can also under certain environmental conditions have stratified distribution with maxima in relatively thin layer. As the vertical structure of the lake ecosystem is rather complex in such stratified lakes as ours, the strategy of research, including sampling techniques, should consider potentially variable and non-homogeneous distributions.

Comparison of trip duration, activity pattern and diving behaviour by Red-tailed Tropicbirds (Phaethon rubricauda) during incubation and chick-rearing

In the tropical marine environment food resources are scarce and often patchily distributed. Consequently, nesting tropical seabirds must balance travelling to productive areas and sharing incubation or providing food to the chick. Changes in foraging behaviour occur when adults switch from feeding only for themselves during incubation to feeding a chick and fulfilling their own energy requirements. Externally attached data-devices were used to compare the duration of foraging trips, flight activity and depth of dives of incubating and chick-rearing Red-tailed Tropicbirds (Phaethon rubricauda) on Christmas Island, Indian Ocean. Adults with chicks had a bimodal pattern of foraging, with alternating short and long foraging trips (mean duration±s.d. of short trips = 3.0 ± 4.1 h, of long trips = 57.4 ± 41.1 h), whereas incubating adults undertook only longer trips (mean duration ± s.d. = 152.9 ± 47.2 h). This strategy is stimulated by partner behaviour, rather than body mass as reported for many other seabirds, and may enable the optimisation of simultaneous food delivery to chicks and self-feeding when local resources are poor. The proportion of time spent in flight (flight activity) by adults with chicks averaged 90.1% during short trips whereas incubating birds spent only 62.4% of their trips flying. Overall mean depth of foraging dives by adults with chicks averaged 0.6 ± 0.3 m during short trips; mean maximum depth of dives by incubating adults were recorded using maximum-depth recorders and were significantly deeper at 10.7 ± 8.7 m, reaching a maximum depth of 25.6 m.

Wear Testing of Composite, Gold, Porcelain, and Enamel Opposing a Removable Cobalt–Chromium Partial Denture Alloy

Eighty percent of all removable partial denture (RPD) frameworks are fabricated from cobalt-chromium (Co-Cr) alloys. The advantages of this material include low density and high modulus of elasticity, hardness, and strength. Hardness is of particular concern when related to excessive wear of natural teeth or restorative materials. The purpose of this study was to compare the differences in localized wear among enamel, composite, gold, and porcelain by a Co-Cr alloy RPD. Thirty-two polished specimens were prepared and positioned in an acrylic-filled custom fixture for testing. Upon optical examination, the highly polished surfaces of the specimens were scratch-free. They were mounted into a water bath fixture and subjected to 250,000 cycles in a wear simulator equipped with a conical Co-Cr stylus specially fabricated to produce localized wear. A posttest was generated, and the profiles were fitted and evaluated using software. The total volume loss and depth of the wear facet on each specimen were analyzed using ANOVA and Fisher's PLSD test. Volume loss (mm3) was as follows: composite, 0.110; gold, 0.021; enamel, 0.008; porcelain, 0.006. The maximum depths (microm) were: composite, 92; gold, 22; enamel, 13; porcelain, 17. Resin composite had significantly higher values (p < 0.0001) of volumetric loss and maximum depth than the other materials. No significant differences were detected among volumetric loss and maximum depth values for gold, enamel, and porcelain. Significant differences for mean wear volume loss and maximum depth were found between composite and gold, enamel, and porcelain. Enamel proved to be wear resistant to the Co-Cr alloy. porcelain and gold appear to be good options for occlusal surfaces opposing a Co-Cr alloy; however, the test composite was not found to be a recommended option.

Ecological studies of marine mammals using a seabed-mounted echosounder

Abstract Doksæter, L., Godø, O. R., Olsen, E., Nøttestad, L., and Patel, R. 2009. Ecological studies of marine mammals using a seabed-mounted echosounder. – ICES Journal of Marine Science, 66: 1029–1036. A seabed-mounted, upward-looking, 38 kHz echosounder (Simrad EK60) was used to monitor cetaceans for 128 d between July 2004 and June 2005. The echosounder was placed at 52°N 30°W at a depth of 910 m, in a frontal area with continuous upwelling creating a hotspot of marine life at all trophic levels. Echo tracks were observed, apparently resulting from one or more animals in close temporal and spatial proximity. The 69 “acoustic detections” were examined with a principal component analysis (PCA) considering mean target strength (TS), group size, and maximum dive depth and duration. The PCA conservatively classified 45 of the acoustic detections as “cetaceans”. Their mean TS values varied between −5 and −36 dB, in agreement with earlier TS measurements of whales and dolphins. Several of the supposed cetaceans were apparently feeding in the “deep-scattering layer” when this ascended at night. This study demonstrates that cetacean behaviour, including swimming, feeding, and vocalizing, can be observed and monitored with stationary active-acoustic instrumentation.

日本の積雪地域の気温・降水量・最深積雪間の関係と気候変化に対する応答の特徴

日本の積雪地域の気温・降水量・最深積雪間の関係と気候変化に対する応答の特徴

Development of the curve of Spee

Ferdinand Graf von Spee is credited with characterizing human occlusal curvature viewed in the sagittal plane. This naturally occurring phenomenon has clinical importance in orthodontics and restorative dentistry, yet we have little understanding of when, how, or why it develops. The purpose of this study was to expand our understanding by examining the development of the curve of Spee longitudinally in a sample of untreated subjects with normal occlusion from the deciduous dentition to adulthood. Records of 16 male and 17 female subjects from the Iowa Facial Growth Study were selected and examined. The depth of the curve of Spee was measured on their study models at 7 time points from ages 4 (deciduous dentition) to 26 (adult dentition) years. The Wilcoxon signed rank test was used to compare changes in the curve of Spee depth between time points. For each subject, the relative eruption of the mandibular teeth was measured from corresponding cephalometric radiographs, and its contribution to the developing curve of Spee was ascertained. In the deciduous dentition, the curve of Spee is minimal. At mean ages of 4.05 and 5.27 years, the average curve of Spee depths are 0.24 and 0.25 mm, respectively. With change to the transitional dentition, corresponding to the eruption of the mandibular permanent first molars and central incisors (mean age, 6.91 years), the curve of Spee depth increases significantly (P < 0.0001) to a mean maximum depth of 1.32 mm. The curve of Spee then remains essentially unchanged until eruption of the second molars (mean age, 12.38 years), when the depth increases (P < 0.0001) to a mean maximum depth of 2.17 mm. In the adolescent dentition (mean age, 16.21 years), the depth decreases slightly (P = 0.0009) to a mean maximum depth of 1.98 mm, and, in the adult dentition (mean age 26.98 years), the curve remains unchanged (P = 0.66), with a mean maximum depth of 2.02 mm. No significant differences in curve of Spee development were found between either the right and left sides of the mandibular arch or the sexes. Radiographic measurements of tooth eruption confirm that the greatest increases in the curve of Spee occur as the mandibular permanent incisors, first molars, or second molars erupt above the pre-existing occlusal plane. On average, the curve of Spee initially develops as a result of mandibular permanent first molar and incisor eruption. The curve of Spee maintains this depth until the mandibular permanent second molars erupt above the occlusal plane, when it again deepens. During the adolescent dentition stage, the curve depth decreases slightly and then remains relatively stable into early adulthood.

Breast Cancer Regional Radiation Fields for Supraclavicular (SC) and Axillary (AX) Lymph Nodes Treatment: Is a Posterior Axillary Boost Field Technique Optimal?

Breast Cancer Regional Radiation Fields for Supraclavicular (SC) and Axillary (AX) Lymph Nodes Treatment: Is a Posterior Axillary Boost Field Technique Optimal?