Geochemical signature of the bed sediments at the outlet of the Ibrahim River (Lebanon): temporal variation.

Bed sediments were collected monthly at the outlet of the Ibrahim River between May 2016 and July 2017. Their physical and chemical characteristics were studied to highlight the impact of seasonal variations and discharge on the sediments' geochemical signatures. Granulometric analysis showed that samples collected after rain events contained abundant sand fractions (> 80%), while the clay fraction was more present at the beginning of the dry season, at low monthly average flows (1 m3/s). Ten major elements, 14 rare earth elements (REE), and 30 trace elements (TE) were analyzed. An excess of CaO reflected the contribution of the carbonate rocks of the Ibrahim karstic springs (30.35 ± 3.91%) but CaO concentration decreased during periods of high water. On another hand, no REE enrichment was detected, both in high and low flows. Most sediments collected at low flow had a pronounced REE depletion that occurred particularly for LREE composition (Nd, Pr, Ce, and La). A negative Ce anomaly (0.992) and a positive Eu anomaly (1.313) were revealed with an average La/Yb ratio of 0.570, reflecting a slight enrichment in HREE. Most studied TE were less concentrated than the averages mentioned in PAAS, UCC, and WSA references. However, a Ze enrichment was mainly due to the regional geochemical background, an As enrichment was associated with anthropogenic contribution, and a Zr enrichment was linked to discharges from pharmaceutical industries located at the river outlet. This study still needs to be complemented binding both spatial and temporal criteria for further fluvial sediments' monitoring of the entire catchment area.

Assessment of sediment and organic carbon exports into the Arctic ocean: The case of the Yenisei River basin.

The export of organic carbon export by the rivers to the oceans either as particulate organic carbon (POC) or dissolved organic carbon (DOC) is very sensitive to climate change especially in permafrost affected catchments where soils are very rich in organic carbon. With global warming, organic carbon export in both forms is expected to increase in Arctic regions. It should affect contemporary biogeochemical cycles in rivers and oceans and therefore modify the whole food web. This study tries to understand complex processes involved in sediment, POC and DOC riverine transport in the Yenisei River basin and to quantify their respective fluxes at the river outlet. The SWAT (Soil and Water Assessment Tool) hydrological model is used in this study to simulate water and suspended sediment transfers in the largest Arctic river. POC and DOC export have been quantified with empirical models, adapted from literature for the study case. First, the hydrological model has been calibrated and validated at a daily time step for the 2003-2008 and the 2009-2016 periods respectively, and its output has been compared with field data for water and sediment fluxes. Based on conceptualization of transfer processes, calibration on climate and soil properties has been performed in order to correctly represent hydrology and sediment transfer in permafrost basins. Second, calibration of empirical models for DOC/POC transport have been performed by comparing their output with field data, available from 2003 to 2016. Our study reveals that SWAT is capable of correctly representing hydrology, sediment transfer, POC and DOC fluxes and their spatial distribution at a daily timescale, and outlines the links between these fluxes and permafrost features. Our simulation effort results in specific sediment, POC and DOC fluxes of 2.97 t km-2 yr-1, 0.13 t km-2 yr-1 and 1.14 t km-2 yr-1 for the period 2003-2016 which are in the range of previous estimates. About 60% of the total fluxes of sediment, DOC and POC to the Arctic Ocean are exported during the two months of the freshet. Spatial analysis show that permafrost-free areas have returned higher daily organic carbon export than permafrost affected zones, highlighting the thawing permafrost effect on carbon cycle in climate change feedback.

Anthropogenic contribution and influencing factors on metal features in fluvial sediments from a semi-arid Mediterranean river basin (Tafna River, Algeria): A multi-indices approach.

Metals in river sediments from a semi-arid Mediterranean basin were investigated from upstream to downstream during contrasting hydrological conditions in 2014 and 2015. The level and origin of the contamination were evaluated using several geochemical and isotopic indicators. Elements were grouped by their level of contamination: high (Pb > Cd > Zn > Cu) and low (Al, Fe, Cr, Co, Ni). Multiple local sources of contamination were identified (industrial, agricultural and domestic waste), as well as very specific ones (gasoline station) and diffuse pollution from atmospheric deposition (gasoline, ores, aerosols). During storm events, the upstream dams can either be secondary sources of contamination or dilutors through particles derived from natural erosion. The contamination was slowed downstream due to the river geomorphology, but eventually washed into the Mediterranean Sea by intense storm events. Naturally derived elements (Co, Ni, Cr, As) were associated with Al, Fe and Mn oxides or clays, and anthropogenic originated metals with phosphorus (Cd and Zn), sulphur (Cu) and POC (Pb enrichment). Cadmium and Pb were the most available metals upstream and at the outlet, but their availability was not strictly related to their degree of contamination. These conclusions could be drawn thanks to an approach by multiple indicators.

Process design and control of a twin screw hot melt extrusion for continuous pharmaceutical tamper-resistant tablet production.

Hot melt extrusion (HME) is a well-known process within the plastic and food industries that has been utilized for the past several decades and is increasingly accepted by the pharmaceutical industry for continuous manufacturing. For tamper-resistant formulations of e.g. opioids, HME is the most efficient production technique. The focus of this study is thus to evaluate the manufacturability of the HME process for tamper-resistant formulations. Parameters such as the specific mechanical energy (SME), as well as the melt pressure and its standard deviation, are important and will be discussed in this study. In the first step, the existing process data are analyzed by means of multivariate data analysis. Key critical process parameters such as feed rate, screw speed, and the concentration of the API in the polymers are identified, and critical quality parameters of the tablet are defined. In the second step, a relationship between the critical material, product and process quality attributes are established by means of Design of Experiments (DoEs). The resulting SME and the temperature at the die are essential data points needed to indirectly qualify the degradation of the API, which should be minimal. NIR-spectroscopy is used to monitor the material during the extrusion process. In contrast to most applications in which the probe is directly integrated into the die, the optical sensor is integrated into the cooling line of the strands. This saves costs in the probe design and maintenance and increases the robustness of the chemometric models. Finally, a process measurement system is installed to monitor and control all of the critical attributes in real-time by means of first principles, DoE models, soft sensor models, and spectroscopic information. Overall, the process is very robust as long as the screw speed is kept low.

[Patients' rights--doctors' duties]. / Patientenrechte--Arztpflichten (I).

On 26 February 2013 the new "Law on Patients' Rights" (hereinafter also the "Law") became effective. This Law strengthens patients' rights vis-à-vis the insurdnce company and also regulates patients' rights regarding their relation to the doctor. This has consequences for the laws on medical liability all doctors must consider. The doctor's performance is and remains a service and such service does not hold any guarantee of success. Nevertheless, this Law primarily reads as a "law on the duties of physicians". To duly take into account these duties and to avoid mistakes and misinterpretation of the Law, the Ethics Committee of the Consortium of Osteosynthesis Trauma Germany (AOTRAUMA-D) has drafted comments on the Law. Brief summaries of its effects are to be found at the end of the respective comment under the heading "Consequences for Practice". The text of the law was influenced particularly by case law, as continuously developed by the German Federal Court of Justice ("BGH"). The implementation of the Law on Patients' Rights was effected by the newly inserted sections 630a to 630h of the German Civil Code (the "BGB"), which are analysed below. The following comments are addressed to physicians only and do not deal with the specific requirements and particularities of the other medical professions such as physiotherapy, midwifery and others so on. Special attention should be paid to the comments on the newly inserted Duty to inform, which has to be fullfilled prior to any diagnostic or therapeutic procedure (sec. 630c para 2 sentence 1 BGB). Under certain conditions the doctor also has to inform the patient about the circumstances that lead to the presumed occurance of a therapeutic or diagnostic malpractice (sec. 630c para. 2 sentence 2 BGB), based on the manifestation of an undesired event or an undesired outcome. As before, the patient's valid consent to any procedure (sec. 630d BGB) is directly linked to the comprehensive and timely provision of information (sec. 630e BGB). Comprehensive documentation obligations regarding all procedures are stipulated in sec. 630f BGB. As before, the burden of proof still rests with the patient, unless a severe malpractice has been established (sec. 630h BGB). The definition of "severe malpractice" remains unchanged and is based on the case law of the Federal Court of Justice (BGH). The patient's obligations to preserve his or her health and to actively support the process of recovery and securing a positive outcome of the treatment are not explicitly mentioned in the Law. Nevertheless, the patient and the physician need to work closely together to achieve a successful result of the treatment. In case the patient does not give his or her cooperation, the physician should consider terminating the treatment relationship.

5 × 5 cm² silicon photonic crystal slabs on glass and plastic foil exhibiting broadband absorption and high-intensity near-fields.

Crystalline silicon photonic crystal slabs are widely used in various photonics applications. So far, the commercial success of such structures is still limited owing to the lack of cost-effective fabrication processes enabling large nanopatterned areas (≫ 1 cm(2)). We present a simple method for producing crystalline silicon nanohole arrays of up to 5 × 5 cm(2) size with lattice pitches between 600 and 1000 nm on glass and flexible plastic substrates. Exclusively up-scalable, fast fabrication processes are applied such as nanoimprint-lithography and silicon evaporation. The broadband light trapping efficiency of the arrays is among the best values reported for large-area experimental crystalline silicon nanostructures. Further, measured photonic crystal resonance modes are in good accordance with light scattering simulations predicting strong near-field intensity enhancements greater than 500. Hence, the large-area silicon nanohole arrays might become a promising platform for ultrathin solar cells on lightweight substrates, high-sensitive optical biosensors, and nonlinear optics.

First assessment of water and carbon cycles in two tropical coastal rivers of south-west India: an isotopic approach.

RATIONALE: The contribution of tropical coastal rivers to the global carbon budget remains unmeasured, despite their high water dynamics, i.e. higher run-off with their basin characteristic of warm temperature. Two rivers draining the western part of the Western Ghats, the Swarna (length 80 km) and Nethravati (147 km) Rivers, were studied for water and carbon cycles. METHODS: The stable isotope ratios of oxygen (δ(18) O values), hydrogen (δ(2) H values) and carbon (δ(13) C values) were used to understand the water circulation, the weathering processes and the carbon biogeochemical cycle. The river water samples were collected during the dry post-monsoonal season (November 2011). RESULTS: The δ(18) O and δ(2) H values of river water suggested that the monsoonal vapour source and its high recycling have a dominant role because of the orographical and tropical conditions. The absence of calcareous rocks has led to dissolved inorganic carbon (DIC) mainly originating from atmospheric/soil CO2 , via rock-weathering processes, and the low soil organic matter combined with high run-off intensity has led to low riverine dissolved organic carbon (DOC) contents. The δ(13) C values increase from upstream to downstream and decrease with increasing pCO2 . There is a positive relationship between the δ(13) CDIC values and the DOC concentrations in these two rivers that is contrary to that in most of the studied rivers of the world. CONCLUSIONS: The higher evapotranspiration supported by tropical conditions suggests that there are higher vapour recycling process in the Swarna and Nethravati basins as studied from the water δ(18) O and δ(2) H values. The basin characteristics of higher rainfall/run-off accompanied by warm temperature suggest that the δ(13) C value of riverine DIC is mainly controlled by the weathering of source rocks (silicates) with variation along the river course by CO2 degassing from the river water to the atmosphere and is less dominated by the oxidation of DOC.

Origin and fate of copper in a small Mediterranean vineyard catchment: new insights from combined chemical extraction and δ65Cu isotopic composition.

For centuries, many Mediterranean catchments were covered with vineyards in which copper was widely applied to protect grapevines against fungus. In the Mediterranean-type flow regime, brief and intense flood events increase the stream water discharge by up to 10 times and cause soil leaching and storm runoff. Because vineyards are primarily cultivated on steep slopes, high Cu fluxes are discharged by surface water runoff into the rivers. The purpose of this work was to investigate the riverine behavior and transport of anthropogenic Cu by coupling a sequential chemical extraction (SCE) procedure, used to determine Cu partitioning between residual and non-residual fractions, with δ(65)Cu isotopic measurements in each fraction. In the Baillaury catchment, France, we sampled soils (cultivated and abandoned), river bed sediments (BS), suspended particulate matter (SPM), and river water during the flash flood event of February 2009. Copper partitioning using SCE show that most of Cu in abandoned vineyard soil was in the residual phase (>60%) whereas in cultivated soil, BS and SPM, Cu was mostly (>25%) in non-residual fractions, mainly adsorbed onto iron oxide fractions. A small fraction of Cu was associated with organic matter (5 to 10%). Calculated enrichment factors (EF) are higher than 2 and the anthropogenic contribution was estimated between 50 to 85%. Values for δ(65)Cu in bulk samples were similar to bedrock therefore; δ(65)Cu on SCE fractions of superficial soils and SPM allowed for discrimination between Cu origin and distribution. Copper in residual fractions was of natural mineral origin (δ(65)Cu close to local bedrock, +0.07‰). Copper in water soluble fraction of SPM (δ(65)Cu=+0.26‰) was similar to dissolved river Cu (δ(65)Cu=+0.31‰). Copper from fungicide treatment (δ(65)Cu=-0.35‰) was bound to organic matter (δ(65)Cu=-0.20‰) without or with slight isotopic fractioning. A preferential adsorption of (65)Cu onto iron oxides (δ(65)Cu=+0.5‰) is shown.

[Is there a life after the trauma surgery? The third period of life]. / Gibt es ein Leben nach der Unfallchirurgie? Die dritte Lebensperiode.

Professor Probst, for long Secretary General of the German Society of Trauma Surgery and yet responsible for the history of trauma surgery, consultancy work in hospital construction and organisation, author and reviewer, forensic experts. Selected literary themes were post-clinic activities for almost two decades.

Doppler sonography of the uterine and ovarian arteries during a superovulatory program in horses.

The aim of the present study was to investigate the effects of a gonadotropin treatment to induce superovulation on ovarian and uterine blood flow and its relationship with steroid hormone levels and ovarian response in mares, using color Doppler sonography. Each of six mares were examined sonographically in five cycles for 3 d (t1 to t3) during the follicular development phase (FDP) beginning at a follicle size of ≥ 22 mm, and for 4 d (D-4 to D-1; D0 = Ovulation) in the preovulatory phase (POP). After each examination, total estrogens (E(tot)) and progesterone (P(4)) levels were determined in peripheral plasma. Cycles 1, 3, and 5 (c(1), c3, c5) were unstimulated cycles (USC); in c2 and c4, the mares were stimulated (SC) with eFSH and inseminated when in estrus at 12 and 24 h after hCG administration. Embryo recovery was performed 6.5 d post ovulation. Cycle 5 c5 was an unstimulated cycle with hCG treatment, insemination, and embryo recovery. Ovarian and uterine blood flow was quantified by the blood flow volume (BFV) and the pulsatility index (PI) in ovarian and uterine arteries. The mean number of ovulations and developing CL was 1.3 ± 0.4 in USC and 4.4 ± 3.1 in stimulated cycles (SC) with no difference (P ≥ 0.05) between the ovaries within mares. No difference (P > 0.05) was observed in utBFV and utPI during FDP between USC and SC, but during POP, utPI was lower (P < 0.05) and utBFV higher (P < 0.001) in SC than USC. The ovBFV was higher (P < 0.01) and ovPI lower (P < 0.05) in SC compared to USC. All uterine and ovarian blood flow parameters were related to the number of developing follicles in SC. Parameters utPI (r = -0.67; P < 0.001) and ovPI (r = -0.53; P < 0.001) were negatively correlated with the number of ovulations on t3, and with the number of collected embryos on t3 (utPI: r = -0.81; P < 0.001), D-4 (utPI: r = -0.64; P < 0.0001), and D-1 (ovPI: r = -0.41; P < 0.01). P(4) levels were not positively correlated with utBFV (P > 0.05), but E(tot) concentrations (D-4: r = 0.790; D3: r = 0.639; P < 0.001; D-1: r = 0.48; P < 0.001) and ovBFV from D-4 to D-1 (r = 0.64; P < 0.001) in SC were. The results of the present study show that in mares treatment with gonadotropins to induce superovulation is associated with a marked increase in uterine and ovarian perfusion, concurrent with the development of multiple follicles and an increase in E(tot) levels. The increased blood flow seems to be related to the effectiveness of ovarian response to stimulation.

Stable carbon isotope evidence for nitrogenous fertilizer impact on carbonate weathering in a small agricultural watershed.

The isotopic signature of Dissolved Inorganic Carbon (DIC), δ(13)C(DIC), has been investigated in the surface waters of a small agricultural catchment on calcareous substratum, Montoussé, located at Auradé (south-west France). The Montoussé catchment is subjected to intense farming (wheat/sunflower rotation) and a moderated application of nitrogenous fertilizers. During the nitrification of the NH(4)(+), supplied by fertilization, nitrate and H(+) ions are produced in the soil. This anthropogenic acidity is combined with the natural acidity due to carbonic acid in weathering processes. From an isotopic point of view, with 'natural weathering', using carbonic acid, δ(13)C(DIC) is intermediate between the δ(13)C of soil CO(2) produced by organic matter oxidation and that of the carbonate rocks, while it has the same value as the carbonates when carbonic acid is substituted by another acid like nitric acid derived from nitrogen fertilizer. The δ(13)C(DIC) values range from -17.1‰ to -10.7‰ in Montoussé stream waters. We also measured the δ(13)C of calcareous molassic deposits (average -7.9‰) and of soil organic carbon (between -24.1‰ and -26‰) to identify the different sources of DIC and to estimate their contribution. The δ(13) C(DIC) value indicates that weathering largely follows the carbonic acid pathway at the springs (sources of the stream). At the outlet of the basin, H(+) ions, produced during the nitrification of N-fertilizer, also contribute to weathering, especially during flood events. This result is illustrated by the relationship between δ(13)C(DIC) and the molar ratio NO(3)(-)/(Ca(2+) + Mg(2+)). Consequently, when the contribution of nitrate increases, the δ(13)C(DIC) increases towards the calcareous end-member. This new isotopic result provides evidence for the direct influence of nitrogen fertilizer inputs on weathering, CO(2) consumption and base cation leaching and confirms previous results obtained using the chemistry of the major ions present in the field, and in soil column experiments.

Trace elements in stream bed sediments from agricultural catchments (Gascogne region, S-W France): where do they come from?

The Gascogne region (SW of France) is cultivated for more than 75% of the area. 83 samples of stream bed sediments were collected in three main Gascogne river basins (Gers, Save and Touch, left tributaries of the Garonne river) to evaluate the impact of agricultural practices on trace elements behavior. Eight potential harmful elements (PHE) (Cr, Co, Ni, Cu, Zn, As, Cd and Pb), four reference elements for normalization (Sc, Cs, Al and Fe) and four major elements (Mn, Ca, Mg and P) were considered. The average trace element concentrations in the fine fractions (<63 microm) are in the decreasing order: Zn>Cr>Ni>Pb>Cu>Co>As>Sc>Cs>Cd. Geochemical investigations and an original approach combining regression analysis and chemical sequential extraction allowed to select the most adequate reference material (regional molasse) and reference element (Cs) for normalization procedure. The enrichment factor (EF) is generally lower than 2.5, particularly for Cr, Ni, Cu, As, Zn; however, 23% of the sampling stations are more contaminated (2.5

Spontaneous cellular uptake of exogenous messenger RNA in vivo is nucleic acid-specific, saturable and ion dependent.

The development of new treatments in the post-genomic era requires methods for safe delivery of foreign genetic information in vivo. As a transient, natural and controllable alternative to recombinant viruses or plasmid DNA (pDNA), purified or in vitro transcribed messenger RNA (mRNA) can be used for the expression of any therapeutic protein in vitro and in vivo. As it has been shown previously, the simple injection of naked mRNA results in local uptake and expression. We show here that this process, in the skin, can greatly be modulated according to the injection solution composition and blocked by an excess of competing nucleic acids or a drug affecting cytosolic mobility. Different cell types at the site of injection can take up the foreign nucleic acid molecules and the protein translated from this is detected for no more than a few days. To test this gene transfer method in humans, we produced in vitro transcribed mRNA under good manufacturing practice (GMP) conditions in a dedicated facility. After injection into the human dermis, we could document the translation of the exogenous mRNA. Our results pave the way toward the use of mRNA as a vehicle for transient gene delivery in humans.

Human peripheral blood mononuclear cells transfected with messenger RNA stimulate antigen-specific cytotoxic T-lymphocytes in vitro.

The efficiency of test vaccines needs to be evaluated by quantification of the triggered cellular immune response. Usually, for these assays, autologous target cells expressing the vaccine antigen are required. In the context of messenger RNA (mRNA)-based vaccinations, the target cells used for the read-out are mRNA-transfected monocyte-derived dendritic cells (Mo-DCs). Their production typically requires samples of 100 ml blood from the patients, and limits the number of assays that can be performed. We show here that fresh peripheral blood mononuclear cells (PBMCs) can be transfected with mRNA by electroporation. Such cells are as efficient as mRNA-transfected Mo-DCs for their ability to activate memory T cells in vitro. Thus, mRNA-transfected PBMCs are a convenient replacement of mRNA-transfected Mo-DCs for the in vitro monitoring of natural or vaccine-induced immune responses.

Polarization of immunity induced by direct injection of naked sequence-stabilized mRNA vaccines.

In the context of developing a safe genetic vaccination strategy we tested and studied globin-stabilized mRNA-based vaccination in mice. This vaccination strategy has the advantages of genetic vaccination (easy production, adaptability to any disease and inexpensive storage when lyophilized), but not the drawbacks of DNA vaccination (long-term uncontrolled expression of a transgene, possibility of integration into the host genome and possible induction of anti-DNA antibodies). We report here that injection of naked beta-globin untranslated region (UTR)-stabilized mRNA coding for beta-galactosidase is followed by detectable translation in vivo. In addition, we show that such a vaccination strategy primes a T helper 2 (Th2) type of response which can be enhanced and shifted to a Th1-type immune response by application of recombinant granulocyte/macrophage colony-stimulating factor 1 day after mRNA injection. Our data demonstrate that the administration of globin UTR-stabilized mRNA is a versatile vaccination strategy that can be manipulated to fit the requirement of antiviral, antibacterial or antitumor immunity.

Total mercury concentrations in an industrialized catchment, the Thur River basin (north-eastern France): geochemical background level and contamination factors.

River bottom sediments and soils were collected from the industrialized Thur River basin (north-eastern France) to assess mercury contamination. The regional geochemical background level of total mercury was evaluated to calculate mercury contamination factors (Fc) in soils and river bottom sediments. Our estimate of the mean background mercury levels in river sediments and soils, not affected by human activities, was 232 ng x g(-1) (range: 27-406 ng x g(-1)). Sediments contaminated by the effluent from a chlor-alkali plant yielded the highest contamination factors (Fc=1784). Contamination factors of surficial soils within 1 km of the industrial site range from 6.3 to 43.6. This contamination is attributed to diffuse atmospheric deposition from this local plant. However, even upstream from this industrial area elevated contamination factors were recorded for river bottom sediments (Fc=3.2 to 26.4) and for one alluvial soil profile (Fc=10). This is possibly due to past pollution resulting from waste water discharges. Mercury contamination in the different horizons of alluvial soils is not correlated with soil organic carbon content, but may be the result of occasional accidental pollution arising from the introduction of contaminated suspended particulate matter by the Thur River during periods of flooding.

Surface properties of calcium phosphate particles for self setting bone cements.

Calcium phosphate cements (CPC), consist of multicomponent powder mixtures of calcium orthophosphates with grain sizes in the region of 1-20 microm. Due to the small particle sizes surface properties as the zeta potential and adsorption processes play a significant role during manufacturing and application. In the context of this work zeta potentials of different calcium phosphates, like dicalcium phosphate anhydride (DPCA) tetracalcium phosphate (TTCP) and hydroxyapatite were measured in various organic/aqueous media with different pH values. The results show a strong dependency of the zeta potential on the kind of suspension medium used associated with different milling properties. The addition of sodium phosphate leads to a pH value dependent stabilization of the particles in the liquid phase; the zeta potential of the surface increases from about -15 to -18 mV in water and from -35 to -45 mV in 0.05 mol/l sodium phosphate solution. Besides the interaction of particles with various antibiotics was determined on the basis of the zeta potential of the surface. The substances partly cause a tremendous change of the surface load. This is accompanied by a change of the rheological properties of the cement paste, the morphology of the hardened cement matrix and a significant deterioration of the application-relevant properties as setting time or mechanical strength.

Time and money: effects of no-shows at a family practice residency clinic.

BACKGROUND: When patients fail to appear for scheduled appointments, the flow of patient care is interrupted, and clinic productivity declines. This study investigated the impact of failed appointments on a clinic by measuring time and money lost after taking into account same-day treatment patients (walk-ins). METHODS: Schedule information was retrieved for 4,055 visits over 20 business days. Data were collected on appointment status (show, no-show, cancel, walk-in), time allocated for the appointment, charges for visit, date and time of the visit, and other appointment information. RESULTS: No-shows and cancellations represented 31.1% of scheduled appointments and 32.2% of scheduled time. Rates of failed appointments varied by type of provider, patient demographics, and patient status (new versus established). Walk-in patients replaced 61.0% of failed appointments but only 42.4% of the time blocked for those appointments. Walk-in visits generated 89.5% of the charges associated with scheduled visits. Over the course of a year, total revenue shortfalls could range from 3% to 14% of total clinic income. CONCLUSIONS: Failed appointments pose financial as well as administrative problems for residency practices. Proactive reminder systems are needed to promote patient attendance.