Sediment and morphological changes along Yangtze River's 500 km between Datong and Xuliujing before and after Three Gorges Dam commissioning.

The impoundment of the Three Gorges Dam on the Yangtze River begins in 2003 and a full pool level is first attained in 2010. This process leads to reciprocal adjustments in flow discharge, sediment transport and morphology downstream of the dam. Based on 26-year recorded hydrologic data 1990-2015 and surveyed bathymetries 1998, 2010 and 2015, this study elucidates, before and after the commissioning of the dam, the alterations along the 500-km reach of the river. Two-dimensional numerical simulations are performed to predict future morphological changes by 2025. The analyses demonstrate that the impoundment modulates the seasonal flow discharges and traps an appreciable amount of sediment, resulting in enhanced erosion potential and coarsening of sediment. On a multi-year basis, the maximum discharge varies by a factor of 1.3 and the corresponding suspended load concentration and transport rate differ by a factor of 3.0 and 3.8, respectively. Combinations of surveyed and simulated bathymetries reveal its morphological responses to the changes. A general pattern of erosion is observed along the reach. In its upper 120 km, the process slows down towards 2025. In the middle 200 km, the erosion shifts, following the gradual impounding, to slight deposition, which then shifts back to erosion around September 2018. In the final 180 km, erosion continues without any sign of de-escalation, which is presumedly ascribed to tidal actions. The reach has not yet achieved a hydro-morphological equilibrium; the riverbed down-cutting is supposed to continue for a while. The combination of the field and numerical investigations provides, with the elapse of time, insight into the morpho-dynamics in the 500 km river reach.

Modeling phosphate transport and removal in a compact bed filled with a mineral-based sorbent for domestic wastewater treatment.

Phosphorus filter units containing mineral-based sorbents with a high phosphate (PO4) binding capacity have been shown to be appropriate for removing PO4 in the treatment of domestic wastewater in on-site facilities. However, a better understanding of their PO4 removal mechanisms, and reactions that could lead to the formation of PO4 compounds, is required to evaluate the potential utility of candidate sorbents. Models based on data obtained from laboratory-scale experiments with columns of selected materials can be valuable for acquiring such understanding. Thus, in this study the transport and removal of PO4 in experiments with a laboratory-scale column filled with a commercial silicate-based sorbent were modeled, using the hydro-geochemical transport code PHREEQC. The resulting models, that incorporated the dissolution of calcite, kinetic constrains for the dissolution of calcium oxide (CaO) and wollastonite (CaSiO3), and the precipitation of amorphous tricalcium phosphate, Ca3(PO4)2, successfully simulated the removal of PO4 observed in the experiments.

The effect of hydraulic loading rate and influent source on the binding capacity of phosphorus filters.

Sorption by active filter media can be a convenient option for phosphorus (P) removal and recovery from wastewater for on-site treatment systems. There is a need for a robust laboratory method for the investigation of filter materials to enable a reliable estimation of their longevity. The objectives of this study were to (1) investigate and (2) quantify the effect of hydraulic loading rate and influent source (secondary wastewater and synthetic phosphate solution) on P binding capacity determined in laboratory column tests and (3) to study how much time is needed for the P to react with the filter material (reaction time). To study the effects of these factors, a 2(2) factorial experiment with 11 filter columns was performed. The reaction time was studied in a batch experiment. Both factors significantly (α = 0.05) affected the P binding capacity negatively, but the interaction of the two factors was not significant. Increasing the loading rate from 100 to 1200 L m(-2) d(-1) decreased P binding capacity from 1.152 to 0.070 g kg(-1) for wastewater filters and from 1.382 to 0.300 g kg(-1) for phosphate solution filters. At a loading rate of 100 L m(-2) d(-1), the average P binding capacity of wastewater filters was 1.152 g kg(-1) as opposed to 1.382 g kg(-1) for phosphate solution filters. Therefore, influent source or hydraulic loading rate should be carefully controlled in the laboratory. When phosphate solution and wastewater were used, the reaction times for the filters to remove P were determined to be 5 and 15 minutes, respectively, suggesting that a short residence time is required. However, breakthrough in this study occurred unexpectedly quickly, implying that more time is needed for the P that has reacted to be physically retained in the filter.

Phosphorus binding to Filtra P in batch tests.

Recent guidelines from the Swedish Environmental Protection Agency recommend stricter regulations for phosphorus (P) reduction in small-scale wastewater treatment, which raises the need for additional and novel treatment steps in small-scale facilities. Following a biological pretreatment, filter systems can be a convenient option. In this study, the P binding capacity of the filter material Filtra P was investigated in batch tests. The batch test method was evaluated with respect to the effects of liquid-to-solid ratio and particle size on P binding capacity. For initial concentrations (c(i)) between 3 and 100 mg L(-1), the P in the solution was completely and rapidly bound to the material, indicating that Filtra P was an efficient substrate for this process. The maximum amount of bound P was 4.3 +/- 0.64 g kg(-1) at c(i) = 300 mg L(-1). The P binding capacity and turbidity measured in the supernatant correlated positively. Turbidity was probably caused by calcium-P precipitates, suggesting precipitation was the major removal mechanism. Neither the liquid-to-solid ratio nor the particle size affected P binding capacity significantly (alpha = 0.05) at c(i) = 1000 mg L(-1), confirming that the conditions used in the batch tests were appropriate. In full-scale applications, the precipitate formed may be at risk of being washed out of the filter, leading to low total P reduction and recovery.

Analysing the mechanical performance and growth adaptation of Norway spruce using a non-linear finite-element model and experimental data.

Thirteen Norway spruce [Picea abies (L.) Karst.] trees of different size, age, and social status, and grown under varying conditions, were investigated to see how they react to complex natural static loading under summer and winter conditions, and how they have adapted their growth to such combinations of load and tree state. For this purpose a non-linear finite-element model and an extensive experimental data set were used, as well as a new formulation describing the degree to which the exploitation of the bending stress capacity is uniform. The three main findings were: material and geometric non-linearities play important roles when analysing tree deflections and critical loads; the strengths of the stem and the anchorage mutually adapt to the local wind acting on the tree crown in the forest canopy; and the radial stem growth follows a mechanically high-performance path because it adapts to prevailing as well as acute seasonal combinations of the tree state (e.g. frozen or unfrozen stem and anchorage) and load (e.g. wind and vertical and lateral snow pressure). Young trees appeared to adapt to such combinations in a more differentiated way than older trees. In conclusion, the mechanical performance of the Norway spruce studied was mostly very high, indicating that their overall growth had been clearly influenced by the external site- and tree-specific mechanical stress.

Digital speckle photography: visualization of mesoflow through clustered fiber networks.

Digital speckle photography (DSP) is used for velocity field measurements inside a fiber network. The width of the channels in which the flow is measured is typically less than 1 mm. Therefore a microscope is used to image the fiber network. When we sample 30 images/s and separate the moving parts of the images from the stationary parts, the velocity field can be deduced with DSP.

Nosocomial candiduria: a review.

Fungal infections of the urinary tract, especially those caused by Candida species, are becoming increasingly common. Often the line between Candida colonization and infection is blurred. Diagnosis typically depends on the discovery of pyuria with high colony Candida counts in the urine. To date, there have been few studies to have addressed treatment regimens for patients with candiduria. Fluconazole has become a mainstay of therapy; however, questions regarding when to treat, whom to treat, and how long to treat are still largely unanswered. Asymptomatic nosocomial candiduria does not frequently require treatment intervention, because morbidity is low and ascending infection and candidemia are rare complications. Treatment decisions are driven by an understanding of the anatomic site of infection. For Candida cystitis, the first-line treatment is fluconazole, given orally. Ascending pyelonephritis usually requires the administration of a systemic antifungal agent and often requires correction of the obstruction or surgical drainage. More research is needed to define diagnostic criteria and therapeutic pathways. This review will attempt to summarize the state of the art of diagnosis and management of candiduria.

Management of candiduria.

The distinction between Candida colonization of the urinary tract and infection is often blurred. Asymptomatic candiduria is particularly common in catheterized intensive care unit patients. To date, few studies have addressed the appropriate treatment regimens for candiduria. Fluconazole has become a mainstay of therapy; however, when to treat, whom to treat, and how long to treat are still largely unanswered questions. Asymptomatic nosocomial candiduria infrequently requires treatment intervention because morbidity is low and ascending infection and candidemia are rare complications. An understanding of the anatomic site of infection drives treatment decisions. More research is needed to define diagnostic criteria and therapeutic pathways. This review attempts to summarize the diagnosis and management of candiduria.

Antibiotics for gram-positive bacterial infections. Vancomycin, teicoplanin, quinupristin/dalfopristin, and linezolid.

Vancomycin is a safe, effective antibiotic for a variety of serious gram-positive infections. Because of emerging resistance in enterococci and staphylococci and the emerging threat of spread of vancomycin-resistant genes to other gram-positive organisms, judicious use of vancomycin should be promoted. Quinupristin/dalfopristin, a streptogramin antibiotic, and linezolid, an oxazolidinone, show promise against some strains of gram-positive bacteria that are resistant to vancomycin.

Exciton storage in semiconductor self-assembled quantum dots

Storage and retrieval of excitons were demonstrated with semiconductor self-assembled quantum dots (QDs). The optically generated excitons were dissociated and stored as separated electron-hole pairs in coupled QD pairs. A bias voltage restored the excitons, which recombined radiatively to provide a readout optical signal. The localization of the spatially separated electron-hole pair in QDs was responsible for the ultralong storage times, which were on the order of several seconds. The present limits of this optical storage medium are discussed.

N-terminal proANF in acute atrial fibrillation: a biochemical marker of atrial pressures but not a predictor for conversion to sinus rhythm. Digitalis in Acute Atrial Fibrillation (DAAF) Trial group.

BACKGROUND: Atrial filling pressures are increased in acute atrial fibrillation, which stimulates the release of atrial natriuretic factor pro-hormone, proANF. METHODS: In a randomized trial comparing digoxin with placebo in 216 patients, we investigated whether the baseline plasma level of N-terminal proANF is a predictor for conversion to sinus rhythm and the relation among N-terminal proANF, conversion to sinus rhythm, and changes in heart rate. RESULTS: N-terminal proANF was increased at baseline and decreased significantly in patients converting to sinus rhythm, whereas it was mainly unchanged in nonconverters. N-terminal proANF was not a predictor of conversion to sinus rhythm. A relation was found between relative changes in heart rate and N-terminal proANF in nonconverters. CONCLUSION: The level of N-terminal proANF does not predict conversion to sinus rhythm, which indicates that hemodynamics per se is not important. There is a correlation between relative changes in heart rate and N-terminal proANF in nonconverters.

Risk factors for enterococcal urinary tract infection and colonization in a rehabilitation facility.

BACKGROUND: We attempted to define the risk factors for urinary tract acquisition of enterococcus in a 155-bed rehabilitation facility in Southeastern Michigan by performing a prospective, case-controlled observational study. METHODS: All cases were identified from daily review of microbiologic records of urine culture results. All urinary isolates of enterococcus species, whether representing infection or colonization, were saved on agar plates for subsequent pulsed-field gel electrophoresis. Thirty-five percent of urinary tract isolates were due to enterococcal species compared with 5% to 15% in adjacent acute-care facilities. A control was defined as the next patient with a nonenterococcal urinary isolate. RESULTS: No differences were found between cases and controls with respect to age, sex, admitting diagnosis, voiding habits, symptoms, laboratory values, geographic location, caregivers, or urinary infection versus colonization. CONCLUSIONS: Prior antibiotic use was more frequent in the patients colonized or infected with enterococcal isolates (78% vs 41%). No evidence was found for a single clone of enterococcal isolates in our facility by DNA analysis, suggesting that the acquisition of enterococcus in the urinary tract was endogenous.

Infection control in ambulatory care.

This article provides a structured review of the English literature focusing on areas that theoretically pose the greatest risk for nosocomial infections in ambulatory care. The review describes variations in methods of surveillance and a general paucity of studies that provide reliable estimates of the risk for infections in the ambulatory environment.

Phialophora verrucosa infection in a BMT patient.

Phialophora is a dematiaceous fungus isolated from soil and wood. Human infections including chromoblastomycosis, mycotic keratitis, cutaneous infections, and prosthetic valve endocarditis have been reported. We report a case of fatal hemorrhage due to Phialophora verrucosa in a patient with prolonged neutropenia undergoing autologous bone marrow transplant (BMT) for acute myelogenous leukemia (AML). Bacterial infections complicated induction and consolidation chemotherapies. Liposomal amphotericin B (LAMB) was given from day +33 to day +72 for febrile neutropenia. Death occurred on day +74 due to tracheal hemorrhage. Autopsy revealed granulation tissue on the posterior wall of the trachea with fungal hyphae on histopathology; the tissue grew Phialophora verrucosa. In vitro susceptibility studies revealed a minimum inhibitory concentration to AmB of 0.1 microg/ml. This represents the first reported case of invasive P. verrucosa in a BMT patient leading to fatal hemorrhage, despite large cumulative doses of LAMB to which the organism remained susceptible.

Invasive Candida guilliermondii infection: in vitro susceptibility studies and molecular analysis.

Candida guilliermondii is rarely isolated from humans. We describe a case of disseminated C. guilliermondii with associated purulent pericarditis, despite high-dose amphotericin B (AmB), in a 19-year-old female with aplastic anemia who underwent BMT. In vitro susceptibility studies of the 13 clinical isolates, two control strains and one environmental isolate revealed a minimum inhibitory concentration (MIC) range of (0.19-1.56 micrograms/ml) for AmB and (1.25-10 micrograms/ml) for fluconazole. Pulsed-field gradient gel electrophoresis was performed to evaluate possible similarities between strains. This case is significant for several reasons, the high degree and prolonged duration of fungemia despite high-dose AmB and concomitant flucytosine, the change in in vitro susceptibility during therapy, the initial misidentification of the yeast isolate, and the invasiveness of the organism. The poor response to therapy may have been due to the severe and sustained neutropenia and the high MICs of C. guilliermondii to AmB.