Managing money flow to safeguard your practice

Whether payments for service come in the form of patient cash or checks, or insurer payments, it is paramount that a doctor implement a strong accounting system to disclose all daily financial transactions. It is also essential that a strong audit trail be part of this accounting system. By taking a few minutes at the end of each day to do the necessary review, dentists protect their income and provide one of the best protections an owner can have against embezzlement. Let the staff know you are on top of the books!     

Critères généraux de conception des réseaux de diodes lasers à rubans couplés par champs évanescents

The aim of this article is to define the general criteria for design of phase-locked diode laser arrays. A general method for designing these devices is presented using the effective index method and the coupled mode theory. The confinement required for the individual diodes is defined, and the allowed structure geometries are determined.     

The Analysis and Improvement of a Current-Steering DAC's Dynamic SFDR—II: The Output-Dependent Delay Differences

For a current-steering digital-to-analog converter (DAC) without an extra output stage, the variation of the output voltage will result in the variation of the output delay. These output-dependent delay differences will deteriorate the spurious-free dynamic range (SFDR) of a high-speed high-accuracy DAC, especially when glitches exist. In this paper, a convenient mathematical model is presented to analyze during design the impact of this kind of delay differences on the SFDR. The results are verified by comparison to the results of more detailed simulations. Also the impact of glitches on this effect is demonstrated. Possible solutions to reduce this impact are discussed and summarized     

探析中国传统植物学知识

<正>约瑟夫·尼达姆[李约瑟](Joseph Needham,1900-1995)曾在《中国科学与文明史》(Science and Civilisation in China)第6卷第1期发表了对中国植物学的专项研究。由此,读者可以了解到:在中国古代医学和     

Membrane performance in combined processes including ozonation or advanced oxidation, powdered activated carbon and coagulation — Investigations in pilot scale

In Luxembourg the largest drinking water production plant treating reservoir water with conventional technology including ozonation is in operation since 1969. Its maximum capacity is 64,000 m³/d. After 40 years of operation the need for both modernizing and extension of capacity to 100,000 m³/d emerged. Nowadays, due to new developments in technology and research it is possible to assess the water treatment processes more effectively with regard to current and future requirements. Against this background, membrane processes combined with conventional and advanced processes were identified as potential option and long term pilot-scale tests were started in June 2008. Different treatment process schemes all including membranes are investigated in a one year pilot plant period. Various treatment steps such as different pre- and post-treatment steps, various membranes and membrane materials and also conventional treatment steps are compared and assessed.     

Analyzing and modeling the performance degradation of flash A/D converters due to substrate noise coupling

This paper presents a model to evaluate the impact of substrate noise on a CMOS regenerative comparator and moreover to predict the resulting performance degradation of a flash analog-to-digital (A/D) converter. The proposed approach initially relates substrate noise to the induced timing uncertainty of the comparator by means of an analytical linear model. In particular, the analysis first focuses on analyzing and expressing the resulting non-uniform sampling distortion in regenerative comparators in the presence of a deterministic ground bounce. Two sources of distortion are identified and evaluated: the input-dependent and the substrate noise-dependent one. For each error contributor, the analysis investigates two cases of timing error, based on the frequency correlation of the interfering signal with the sampling clock. The properties (number and power of distortion tones) of the sampling error spectrum are found to be highly dependent on the spectral content of the interfering signal and the sampling clock, while the model captures accurately the induced distortion. Subsequently, the linear model is extended to estimate the degradation of flash A/D converters and is utilized to predict the performance of practical flash and time-interleaved converters in the presence of substrate noise.     

Tests for the Use of La2Mo2O9‐based Oxides as Multipurpose SOFC Core Materials

The mixed ionic–electronic conductivity under dilute hydrogen, the stability and the catalytic activity under propane:air type mixtures of a series of LAMOX oxide‐ion conductors have been studied. The effect of exposure to dilute hydrogen on the conductivity of the β‐La₂(Mo_{2 – y}W_y)O₉ series at 600 °C depends on tungsten content: almost negligible for the highest (y = 1.4), it is important for La₂Mo₂O₉ (y = 0). In propane:air, all tested LAMOX electrolytes are stable at 600–700 °C, but get reduced when water vapour is present. La₂Mo₂O₉ is the best oxidation catalyst of the series, with an activity comparable to that of nickel. The catalytic activity of other tested LAMOX compounds is much lower, (La_1.9Y_0.1)Mo₂O₉ showing a deactivation phenomenon. These results suggest that depending on composition, La₂(Mo_{2 – y}W_y)O₉ compounds could be either electrolytes in single‐chamber SOFC and dual‐chamber micro‐SOFC (y = 1.4) or anode materials in dual‐chamber SOFC (low y) or oxidation catalysts in SOFCs operating with propane (y = 0).     

Bacterial formation of tooeleite and mixed arsenic(III) or arsenic(V)-iron(III) gels in the Carnoulès acid mine drainage,France. A XANES,XRD, and SEM study

The oxidation of Fe(II) in acid mine drainage (AMD) leads to the precipitation of Fe(III) compounds which may incorporate toxic elements, such as arsenic (As), within their structure or adsorb them at their surface, thus limiting their mobility. The present work provides evidence for spatial and seasonal variations of microbial activity that influence arsenite oxidation and As immobilization in the heavily contaminated AMD from the Carnoulès mine, Gard, France ([As III] = 80 to 280 mg x L(-1) in the acidic spring draining the waste-pile). In the first tens of meters of the AMD, the rapid oxidation of Fe(II) leads to the coprecipitation of large amounts of As with Fe(III) in bacterial mats. XRD, XANES, and SEM analyses of sediments and stromatolite samples revealed the unusual formation of As(III)-rich compounds, especially nanocrystalline tooeleite, Fe6(AsO3)4(SO4)(OH)4 x 4H2O, a rare ferric arsenite sulfate oxy-hydroxide mineral, together with XRD-amorphous mixed As(III)/As(V)-Fe(III) oxy-hydroxide compounds. In the wet season, the suspended sediments of the upstream zone essentially consist of tooeleite associated with am-As(III)-Fe(III) oxy-hydroxides, while am-As(V)-Fe(III) oxy-hydroxides, having As:Fe molar ratios as high as 0.6-0.8, dominate in the dry season. Comparing natural and bioassay samples revealed that the formation of As(III)-rich compounds in the wet season may be related to the metabolic activity of bacterial strains able to oxidize Fe(II) but not As(III). One of these strains, having an Acidithiobacillus ferrooxidans genotype, has been isolated from the Carnoulès AMD. In contrast, the formation of As(V)-rich compounds in the dry season can be related to both biotic and abiotic oxidation of As(III) to As(V). Some Thiomonas strains isolated from the Carnoulès AMD were shown to be able to catalyze the oxidation of As(III) to As(V) in solution. Therefore, they can promote the formation of mixed As(V)-Fe(III) oxy-hydroxides, provided enough Fe(II) oxidizes. These results yield a better understanding of natural processes at this site and may help in designing efficient As-removal processes.     

Barium Borosilicate Sealing Glasses Synthesized by a Sol–Gel Process: Chemical Interactions with a Stainless Steel and Gas‐Tightness of a SOFC

Several glasses synthesized by sol–gel route and based on the BaO–B₂O₃–X–Al₂O₃–SiO₂ (X = CaO, MgO) glass system have been investigated to evaluate their applicability as sealant for solid oxide fuel cell (SOFC). Chemical interactions with K41X stainless steel and hydrogen‐tightness of these materials were evaluated after operations at high temperatures over 1,000 h in air atmosphere. Formation of a new phase at the steel–glass interface and formation of porosity in the glass were observed and determined as critical problems over mid‐term operations. The role of MgO is important to obtain a gas‐tight sealing. Application of the glass paste without binder addition was performed in order to avoid possible residual porosity related problems. The best glass was finally used as sealant between anodic and cathodic compartments in complete SOFCs operated at 760 and at 800 °C. Open circuit voltages and power densities of the cells were recorded during the first hours of operation.