Lake Success Research Articles

Lithofacies and depositional processes from a Carboniferous lake, Sierra de Narváez, Northwest Argentina

Thick and widespread Late Carboniferous lacustrine successions occur in the Sierra de Narváez area, northwest Argentina. A detailed lithofacies analysis forms the basis for the definition of fourteen lithofacies clustered into three assemblages. The delta assemblage consists of channelized cobble to pebble conglomerates, quartz-rich sandstones, and carbonaceous mudstones. This assemblage is present at the top of the lake succession and records the progradation of a short-headed stream delta. Wave- and current-rippled sandstones, and a heterolithic facies make up the shallow-lake assemblage. The nearshore area was probably composed of small bars, shoreline sand flats and low-energy sand-mud flats. The deep-lake assemblage is represented by two types of coarsening- and thickening-upward lithofacies sequences. The first type consists, from bottom to top, of laminated mudstones, thin-bedded turbidites, classic turbidites and massive sandstones. Each sequence is thought to represent turbidite lobe progradation in a basinal setting. The second type of sequence consists, from base to top, of underflow current sandstones and mudstones, thin-bedded and classic turbidites, deformed sandstones and hummocky cross-stratified sandstones. Each sequence records progradation of turbidite lobes on the delta front. The analyzed lithofacies record deposition in a hydrologically open lake. Final lake infill was related to the progradation of a deltaic system. It is suggested that four distinct processes controlled sediment transport and deposition in the Carboniferous lake: (1) delta progradation, (2) episodic sediment density surges, (3) river plume dispersion, and (4) wave action. During periods of high discharge, fine to very fine sand and silt bypassed mouth-bar zones and were deposited farther into the lake by underflow currents. Sands supplied by the delta system accumulated in the upper delta front in unstable conditions and were later redeposited by episodic turbidity currents. Wave action was able to rework shallow-water sands supplied by the delta system or emplaced by turbidity currents.

Letters: Questions Patients Should Ask about Laparoscopic Cholecystectomy

Corrections15 May 1994Correction: Questions Patients Should Ask about Laparoscopic CholecystectomyFREERaphael P. Nenner, MDRaphael P. Nenner, MDIsland Peer Review Organization; Lake Success, NY 11042Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-120-10-199405150-00024 SectionsAboutVisual AbstractPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail TO THE EDITOR:Two sentences in a recently published letter [1] conveyed meanings other than those intended. In the sentence, “Ransohoff and Gracie appropriately advise caution in interpreting the published series, given the small number of open cholecystectomies,” the word “open” should be replaced by “laparoscopic”.In the fifth paragraph, the Island Peer Review Organization hotline described was not uniquely established for inquiries from beneficiaries regarding laparoscopic cholecystectomy but for inquiries on various medical care issues, including laparoscopic cholecystectomy. Thus, the sentence “To assist patients in assessing the experience and competency of their potential laparoscopic surgeon, in 1992 we instituted a toll-free hotline on laparoscopic cholecystectomy for Medicare and Medicaid beneficiaries,” should read “To assist patients with medical care issues, in 1992 we instituted a toll-free hotline for Medicare and Medicaid beneficiaries”.REFERENCE1. Nenner RP, Imperato PJ, Will TO. Questions patients should ask about laparoscopic cholecystectomy (Letter). Ann Intern Med. 1994; 120:443. Google Scholar Comments0 CommentsSign In to Submit A Comment Author, Article, and Disclosure InformationAffiliations: Island Peer Review Organization; Lake Success, NY 11042 PreviousarticleNextarticle Advertisement FiguresReferencesRelatedDetails Metrics 15 May 1994Volume 120, Issue 10Page: 894KeywordsCholecystectomyLaparoscopic cholecystectomyMedicarePatientsPeer reviewSurgeons Issue Published: 15 May 1994 CopyrightCopyright © 1994 by American College of Physicians. All Rights Reserved.PDF DownloadLoading ...

Endosonography of stenotic esophageal carcinomas: Preliminary experience with an ultra-thin, balloon-fitted ultrasound probe in four patients

Endosonography (ES) is a generally accepted technique for the pre-operative staging of malignant tumors in the upper or lower gastrointestinal tract. One of the main indications for ES is the pre-operative staging of esophageal carcinoma, where T (depth of tumor invasion) and N (regional lymph node metastasis) stage are vital for determining prognosis.1,2 In series that have been published, an accuracy of 85% for T stage and approximately 80% for N stage have been reached.3-7 A major limiting factor for the use of ES is the fact that a considerable number of esophageal lesions cannot be traversed with standard echo-endoscopes (Olympus GF-UM3 or GF-UM20, Olympus America Inc., Lake Success, N.Y.).

Lake Ecosystem Energetics: The Missing Management Link

ABSTRACT Phosphorus plays a central role in the bioenergetics of organisms and ecosystems (recall Adenosine Triphosphate [ATP], substrate level phosphorylation, cyclic and noncyclic photophosphorylation). It is a role which no other atom can duplicate. Phosphorus is of paramount importance in lake management because it most often limits the degree of phytoplanktonic autotrophy (algae growth). However, many other aspects of lake ecosystem structure and function offer substantial promise for the future of lake management and restoration. One such aspect, ecosystem energetics, is too often neglected or misunderstood by the lake manager. There are fundamental differences between autotrophication and allotrophication, trophic and detrital dynamic structures, eutrophication and lake succession, and how these ecosystem components and processes can be effectively managed. An understanding of the nitrogen, sulfur, iron, and phosphorus cycles of lakes yields insight into new restoration technologies (e.g., alum sur...

Lipid production in relation to phytoplankton succession in lakes

Lipid production in relation to phytoplankton succession in lakes

The depositional environments and tectonic development of a Mesozoic intra-arc basin, Atacama Region, Chile

AbstractA thick succession of continental redbeds was deposited in a 50 km wide intra-arc basin on the Andean active continental margin in the Atacama region of northern Chile during early Cretaceous times. Upper Jurassic to early Cretaceous marine limestones were buried by the seaward progradation of a succession of coastal dunes, saline lakes and sandflats. Aeolian dune fields migrating towards the east across these coastal plains became stabilized by the growth of vegetation. Interdune alluvial areas between the sand dunes and dune fields developed into extensive alluvial braid plains which were in turn superimposed by alluvial fans. These fans were inundated by a regionally extensive saline lake produced by tectonic or volcanic damming of the sedimentary basin. This lake dried up leaving a large area of playa-lake mudflats. The climate was warm and semi-arid with a low and seasonal rainfall. Parts of the area supported a substantial vegetation of woody plants, together with a vertebrate fauna of dinosaurs, pterosaurs and crocodiles. The continental redbeds were derived from a volcanic source and were deposited on continental crust in a deep but narrow, north-south elongated, fault-bounded graben. This extensional basin formed in an intra-arc setting within an active andesitic volcanic chain. Upwards-coarsening sedimentary successions were the product of uplift of the fault-bounded margins of the basin.

Vegetation succession in lakes in the coastal fringe of West Connemara, Ireland

Abstract It is hypothesized that the recent intensification of agricultural practice in the coastal fringe of West Connemara, Ireland, has affected the vegetation of vulnerable ecosystems like lakes and wetlands. Lakes and wetlands, arranged in three transects running inland from the coast, were studied to detect an assumed decrease in the effects of eutrophication as a result of a decrease in the intensity in land use. The data obtained from the vegetation survey in 1988 were compared with those collected at the same sites in 1975. The data were subjected to various multivariate statistics to detect changes in species composition and relationships between these changes and environmental variables such as pH and orthophosphate concentration in the surface waters. Changes in species composition are accompanied by changes in environmental factors; notably a marked increase in orthophosphate level indicating an anthropogenic origin for most of the observed changes in vegetation. Changes in species composition have also been used to construct a transition matrix for sites between 1975 and 1988. This has served as a basis for a prognosis on the state of the vegetation at these sites circa 2000. Data have also been grouped to indicate lake‐specific patterns in the changes. The dynamics of all plant species have been established based on their frequency of disappearance from sites since 1975 and their rate of establishment in new sites in 1988. Special attention has been given to species from the red data list. It is concluded that over the past 13 years species diversity decreased in the whole area, and especially in coastal lakes. Red data list species appeared to be the more vulnerable ones.

Magnetic measurements recording Late Holocene man‐induced erosion in S. Greenland

Magnetic measurements have been carried out on four lake sediment successions in interior S. Greenland. The longest record extends back to 7000 C14 years BP. Based on the magnetic susceptibility six units have been distinguished. The results of the magnetic analyses show a close correlation between the four investigated sites, corroborated by pollen stratigraphy and radiocarbon dates. The period after the deglaciation, lasting for some thousand years, was characterized by sparse vegetation on the unstable soils. Erosion rates were high as revealed by the high concentration of magnetic minerals. Along with the spreading of dwarf‐shrub heaths the soils stabilized, reducing the eroding capacity, and are seen as decreasing concentrations of magnetic minerals in the sediments. During the subsequent period there seems to have been an equilibrium between climate and vegetation resulting in minimal erosion. The arrival of the Norsemen in c. AD 1000, introducing cattle and cutting down the ‘forests’, seems to have caused a disturbance in the fragile environment. It destroyed the attained equilibrium and is seen in the sediment records as an increase in magnetic concentrations. Due to the disappearance of the Norsemen in the 15th century, or slightly later, a new phase of soil stabilization began. A new and still ongoing phase of even more severe soil erosion is connected with the reappearance of man, now as a sheep breeder, in the beginning of this century. Magnetic concentrations are again high, being in the same order of magnitude as during early Holocene time.

A prospective, randomized comparison of the Pipelle endometrial sampling device with the Novak curette

This prospective, randomized study compares sample adequacy, pain associated with endometrial biopsy, and correlation of endometrial histologic sampling with hysterectomy histologic results in specimens obtained by the Pipelle (Unimar Inc., Wilton, Conn.) device (N = 149) and the Novak (Miltex, Inc., Lake Success, N.Y.) curette (N = 126). During a 2-year period, patients with abnormal uterine bleeding seen in our ambulatory care facility were enrolled in this trial, unless they did not wish to participate or had a positive pregnancy test result. Patients in both groups were similar with respect to mean gravidity, parity, and menopausal status, although patients in the Novak group were older (43.4 vs 39.1 years, p = 0.005). Patients undergoing Novak biopsy had a mean pain score of 4.36 with 22 of 126 (17%) reporting severe pain, whereas patients undergoing Pipelle biopsy had a mean pain score of 3.21 with only 10 of 149 (6.7%) reporting severe pain (p less than 0.05). These pain scores were not affected by menstrual day, gravidity, parity, or menopausal status. Insufficient tissue was reported in 12.8% of patients in the Pipelle group compared with 9.5% in the Novak group (p greater than 0.05). Fifty patients underwent subsequent hysterectomy. In 48 of 50 (96%), the pathologic results at hysterectomy were in agreement with the histologic findings at endometrial sampling. This clinical trial suggests that Pipelle biopsy appears to be as effective as the Novak curette in obtaining an adequate specimen for histologic analysis and is associated with less pain.

The Spi Group: a post-Archean, pre-2.1 Ga rift succession, Trans-Hudson hinterland

A succession of mafic flows intercalated with sandstone and overlain by conglomerate, herein named the Spi Group, lies unconformably on Archean basement and is preserved in a syncline near Spi Lake, N.W.T. An alluvial fan setting near active rift fault escarpments is the interpreted environment of deposition. The nearby Montgomery Lake Group, Mackenzie Lake metasediments, and Padlei Formation at the base of the Hurwitz Group are possible correlatives of the Spi Group; diabase dykes of the Kaminak swarm, common in the Archean basement, are possibly related to the mafic flows. Correlation with the upper, coarse clastic part of the Hurwitz Group (Tavani Formation) is discounted because the Spi conglomerate does not contain clasts of Hurwitz lithology. The Montgomery Lake, Padlei and Spi successions are interpreted as being rift-related, and are older than the 2.1 Ga gabbro that intrudes the Hurwitz Group. Recognition of widespread rifting in this part of the Hearne Province constrains tectonic modelling of the preorogenic history of the Trans-Hudson hinterland.

A prospective, randomized comparison of the Pipelle endometrial sampling device with the Novak curette

This prospective, randomized study compares sample adequacy, pain associated with endometrial biopsy, and correlation of endometrial histologic sampling with hysterectomy histologic results in specimens obtained by the Pipelle (Unimar Inc., Wilton, Conn.) device (N = 149) and the Novak (Miltex, Inc., Lake Success, N.Y.) curette (N = 126). During a 2-year period, patients with abnormal uterine bleeding seen in our ambulatory care facility were enrolled in this trial, unless they did not wish to participate or had a positive pregnancy test result. Patients in both groups were similar with respect to mean gravidity, parity, and menopausal status, although patients in the Novak group were older (43.4 vs 39.1 years, p = 0.005). Patients undergoing Novak biopsy had a mean pain score of 4.36 with 22 of 126 (17%) reporting severe pain, whereas patients undergoing Pipelle biopsy had a mean pain score of 3.21 with only 10 of 149 (6.7%) reporting severe pain (p < 0.05). These pain scores were not affected by menstrual day, gravidity, parity, or menopausal status. Insufficient tissue was reported in 12.8% of patients in the Pipelle group compared with 9.5% in the Novak group (p>0.05). Fifty patients underwent subsequent hysterectomy. In 48 of 50 (96%), the pathologic results at hysterectomy were in agreement with the histologic findings at endometrial sampling. This clinical trial suggests that Pipelle biopsy appears to be as effective as the Novak curette in obtaining an adequate specimen for histologic analysis and is associated with less pain. This prospective, randomized study compares sample adequacy, pain associated with endometrial biopsy, and correlation of endometrial histologic sampling with hysterectomy histologic results in specimens obtained by the Pipelle (Unimar Inc., Wilton, Conn.) device (N = 149) and the Novak (Miltex, Inc., Lake Success, N.Y.) curette (N = 126). During a 2-year period, patients with abnormal uterine bleeding seen in our ambulatory care facility were enrolled in this trial, unless they did not wish to participate or had a positive pregnancy test result. Patients in both groups were similar with respect to mean gravidity, parity, and menopausal status, although patients in the Novak group were older (43.4 vs 39.1 years, p = 0.005). Patients undergoing Novak biopsy had a mean pain score of 4.36 with 22 of 126 (17%) reporting severe pain, whereas patients undergoing Pipelle biopsy had a mean pain score of 3.21 with only 10 of 149 (6.7%) reporting severe pain (p < 0.05). These pain scores were not affected by menstrual day, gravidity, parity, or menopausal status. Insufficient tissue was reported in 12.8% of patients in the Pipelle group compared with 9.5% in the Novak group (p>0.05). Fifty patients underwent subsequent hysterectomy. In 48 of 50 (96%), the pathologic results at hysterectomy were in agreement with the histologic findings at endometrial sampling. This clinical trial suggests that Pipelle biopsy appears to be as effective as the Novak curette in obtaining an adequate specimen for histologic analysis and is associated with less pain.

Appropriate Use and Regulatory Control of Benzodiazepines

Appropriate Use and Regulatory Control of Benzodiazepines

Video small bowel enteroscopy: early experience with a prototype instrument

A commercial grade of India ink was used and prepared in the following manner: Higgins black India (4418) waterproof drawing ink was diluted with sterile bacteriostatic water in a ratio of 5 parts ink to 2 parts water. This was done to allow the ink to pass through a filter more easily. Ink (114 ml) was mixed with 46 ml of water in a 250-ml Vioflex bag. The solution was then passed through a Travenol 5-/-Lm pore size particulate filter into sterile lO-ml vials to remove any large particulate material. The vials were then autoclaved for 40 min. Sterility of opened vials was 2 hours in duration, and unopened vials were considered sterile for 6 months. Colonic injection catheters (Wilson Cook Inc., WinstonSalem, N.C. or Olympus Corporation of America, Lake Success, N.Y.) were used with a 3-ml syringe to inject 0.1 ml of ink into the submucosa at points just proximal and distal or to the right and left of the excised lesion after the polypectomy in order to bracket the area to be re-examined (Fig. lC). If this area is within the reach of a flexible sigmoidoscope, esophageal variceal injection needles can be used.

Geology of Salt Lake City, Utah, United States of America

Geology of Salt Lake City, Utah, United States of America

Predicting Success of Walleye Stocking Programs in the United States and Canada

Abstract We developed a model to predict the probability of establishing a reproducing population of walleye (Stizostedion vitreum) in lakes and reservoirs in North America. A list of 542 lakes and reservoirs where walleye stocking occurred was obtained by questionnaire survey. Water quality and morphometric data for these systems were obtained from STORET, the national computer data base of the Environmental Protection Agency, and various reports. Two stepwise discriminate analyses were performed on normalized data; the variables area, maximum depth, and pH were found to be significantly related to walleye success in lakes. In addition, the variable date of dam closure was included in the reservoir data set. Using a jackknife discriminate analysis, 71% of the lakes and 72% of the reservoirs were classified correctly. Use of our model increases the probability of predicting the establishment of a self-sustaining walleye population by about 20%.

Holological study of lakes from an entropy viewpoint - Lake Mendota

The monthly entropy fluxes associated with direct, diffuse and reflected solar radiation in Lake Mendota are calculated from the corresponding energy data of the lake. Also, the monthly entropy fluxes associated with infrared radiation, evaporation and sensible heat are estimated. The net entropy flow into the lake becomes negative; that is, the lake absorbs ‘negative entropy’ from its surroundings. In this respect, the lake can be regarded as a ‘superorganism’, which has ordered structures and functions in it similar to a biological organism. The change of entropy content is computed from the change of heat-storage and the mean temperature of the lake. From the net entropy flow and the change of entropy content, the entropy production is calculated. Entropy production is large in summer and small in winter; it oscillates with a period of 1 year. The monthly entropy production ( S prod) is a linear function of the monthly solar energy absorbed by the lake ( E solar): S prod= a+ bE solar, a=0.006 MJ m −3 month −1 K −1 and b=2.29 × 10 −4 m −1 K −1. The values ( a, b) are holistic indices which characterize the lake from an entropy viewpoint. Other indices of similar nature are also introduced. Comparison of these quantities in Lake Mendota (eutrophic) with those in the northern basin of Lake Biwa (oligo-mesotrophic) shows that processes of eutrophication or succession are accompanied by the increase of magnitudes of these indices that are related to entropy production. The increase of entropy production will be an entropy principle in some stage of ecological succession in lakes, and also in other ecological systems. A hypothesis is presented: the whole span of ecological succession consists of three phases: developmental stage (early stage) in which entropy production increases with time, stationary stage (intermediate stage) in which entropy production is kept constant, and senescent stage (later stage) in which entropy production decreases with time. These trends will be applied to Lotka-Odum's power and also Hirata-Ulanowicz's ascendency.

Arthur Donaldson Smith and the Exploration of Lake Rudolf. By Pascal James Imperato. Lake Success, New York: Medical Society of the State of New York, 1987. Pp. vii + 96. $10.00 (paperback).

Arthur Donaldson Smith and the Exploration of Lake Rudolf. By Pascal James Imperato. Lake Success, New York: Medical Society of the State of New York, 1987. Pp. vii + 96. $10.00 (paperback). - Volume 30 Issue 1

Potential Determinants of Stable Catch in the Brook Trout (Salvelinus fontinalis) Sport Fishery in Quebec

Evaluation of four existing empirical models of fish yield showed their applicability to be limited for the brook trout (Salvelinus fontinalis) sport fishery in the Laurentian shield because these models explained &lt; 60% of the variation in catch. In at least 80% of the lakes, observed catch exceeded that predicted by two of the models. The other models overestimate catch by 100% or more in at least 25% of the lakes. As a first step to improve these models, we identify correlates of "stable catch," defined by the absence of a significant temporal trend in fishing success in lakes for which at least five consecutive years of data were available. Data available or calculable from government sources and maps were used to construct models that identified fish size, lake trophy, altitude, and pH as promising correlates. A second series of models based on our own field determinations confirmed these findings. After fishing effort had been taken into account, these variables reduced the unexplained variation by up to 50%. Although our estimates of trophy and acidity were crude, this study suggests that these indicators should be included in future models to describe and predict the yield of sport fisheries.

The feeding of Sarotherodon mossambicus (Family: Cichlidae) with comments on its colonization success in dry zone man-made lakes in Sri Lanka

The feeding of <i>Sarotherodon mossambicus</i> (Family: Cichlidae) with comments on its colonization success in dry zone man-made lakes in Sri Lanka

Reconstruction of Late‐Glacial lake‐level fluctuations in The Netherlands based on palaeobotanical analyses, geochemical results and pollen‐density data

The Late‐Glacial infills of three lake successions in The Netherlands have been analysed for their palaeobotanical content (pollen, macroremains) as well as for their physical and chemical characteristics. The macro‐botanical analysis in association with the pollen analysis permitted the reconstruction of relative lake level fluctuations for each lake. There appeared to be good agreement between the three lake successions. Supporting evidence for the presence of alternating dry and wet phases was found in the geochemical results. The termination of the Bölling biozone coincides with a lowering of the lake levels that persisted throughout the Older Dryas. Water levels restore at the beginning of the Allerod biozone. Several fluctuations are recognized during the Allerod. The end of the Alleröd is characterized by a second major lowering in the lake levels, leading to an interruption in the sedimentation in cores from the fringe zone. Water depth increases at the beginning of the Younger Dryas biozone. A third major minimum in the lake levels is reached towards the end of the Younger Dryas biozone, probably explaining the recurrent hiatus at the transition to the Holocene record. Pollen concentration data in association with chronostratigraphical data provided the construction of sedimentation rate curves. Minima in these sedimentation rate curves appeared to correlate with periods of low lake level. The loss on ignition curve in association with the sedimentation rate data allowed an approximation of the organic production of the lakes involved. It revealed that the darker appearance of the Allerödin the lithologycan be ascribed mainly to a retardationin the sedimentation rate and not to a major increase in the organic production of the lakes.