[Assessing the clinical competence of dental students]. / Het beoordelen van de klinische competenties van studenten tandheelkunde.

Nowadays, the competences of dental students are tested more on the basis of quality of their achievements than the quantity. 'Objective Structured Clinical Examinations' (OSCEs) can be used in a pre-clinical phase to test these clinical competences. For the clinical phase, the general examination and the digital portfolio have been developed. Tests are used to stimulate the learning process and to determine whether students are ready for the next step; in addition, the quality of the programme is protected by the set of examinations. The results of the last 5 general examinations reveal the pattern that the number of correct answers increases as the study progresses. The Amsterdam Academic Centre for Dentistry (ACTA) introduced a digital portfolio which was evaluated 1 year later with the help ofan anonymous questionnaire. Students judged the use of the digital portfolio in the clinic to be useful but also costly in time.

Implementing an Objective Structured Clinical Examination (OSCE) in dental education: effects on students' learning strategies.

OBJECTIVES: To investigate the effect of an Objective Structured Clinical Examination (OSCE) on dental students' learning strategies and competence to manage periodontal diseases in patients. The implemented OSCE was expected to be superior to the existing Written Exam in fostering the acquisition of clinical competencies in terms of study strategies that are more oriented towards clinical practice, longer study time, greater clinical proficiency, and more realistic self-assessment. MATERIAL AND METHODS: After a clinical course in periodontology, 72 third year dental students were assessed summatively, either using a Written Exam or an OSCE (P-OSCE). The students were informed beforehand about the assessment formats. The self-assessed clinical competence, study time and strategies (i.e. practice with a manikin, peers and patient case) were evaluated by means of a questionnaire. After a comprehensive dental care course, all 72 students were assessed by an overall end-of-year OSCE, in which three periodontal stations were included 'measuring pockets', 'educating patients' and 'tracing an X-ray with bone-loss'. The competence of the previous Written Exam group and the P-OSCE group was investigated by determining the mean scores and pass-fail scores of three periodontal test-stations as well as the total score of the end-of-year OSCE. The degree of realistic self-assessment was studied by correlating the self-assessed competencies as evaluated by means of the questionnaire with the total score of the end-of-year OSCE. RESULTS: Self-assessed clinical competence, study time and study strategies showed no differences between the P-OSCE and the Written Exam-group. The clinical competence determined in the test-station 'measuring pockets' in the end of year overall OSCE was higher for the P-OSCE group (P = 0.05) when compared with the Written Exam group; the two groups performed equally well in the test station 'educating patients', whereas the performance in 'tracing an X-ray with bone-loss' was better in the Written Exam group. This group also had a higher total score in the end-of-year OSCE (P = 0.05). The degree of realistic self-assessment was higher in the P-OSCE group than in the Written Exam group: in the P-OSCE group the self-assessed clinical competencies correlated significantly with the total score of the overall end-of-year OSCE (P < or = 0.05). CONCLUSIONS: No effects of the implementation of an OSCE in undergraduate periodontal education were observed in study strategies, but the implementation of an OSCE in undergraduate periodontal education appears to stimulate learning, resulting in greater achievement of specific clinical competence and a greater level of realistic self-assessment.

Microsecond pulsed optical parametric oscillator pumped by a Q-switched fiber laser.

We report on what is to our knowledge the first optical parametric oscillator (OPO) pumped by microsecond pulses from a wavelength-tunable solid-state laser. The singly resonant OPO (SRO) is based on a periodically poled LiNbO3 crystal and pumped with 2.1-micros-long pulses from an actively Q-switched Yb fiber laser. At an average fiber laser power of 3.6 W, the SRO generates 1.9-micros-long pulses with a repetition rate of 25 kHz and an average power of 560 mW at 3360 nm. The SRO was tuned from 1518 to 1634 nm (signal) and from 3145 to 3689 nm (idler) via the crystal temperature and poling period. By all-electronic tuning of the fiber laser wavelength over 19 nm, tuning of the mid-infrared idler wavelength over 195 nm was achieved.

Rapidly tunable continuous-wave optical parametric oscillator pumped by a fiber laser.

We report on rapid, all-electronically controlled wavelength tuning of a continuous-wave (cw) optical parametric oscillator (OPO) pumped by an ytterbium fiber laser. The OPO is singly resonant for the signal wave and consists of a 40-mm-long periodically poled lithium niobate crystal in a four-mirror ring cavity. By tuning of the fiber-laser wavelength over 33 nm through an intracavity acousto-optic tunable filter, the OPO idler wavelength is tuned from 3160 to 3500 nm in 330 micros, corresponding to an idler frequency-tuning speed of 28 THz/ms. At a fiber-laser power of 6.6 W at 1074 nm, the singly resonant OPO generates 1.13-W cw idler radiation at 3200 nm.

Fiber-laser-pumped continuous-wave singly resonant optical parametric oscillator.

We report on what is to our knowledge the first continuous-wave (cw) optical parametric oscillator (OPO) that is pumped by a tunable fiber laser. The OPO is singly resonant for the signal wave and consists of a 40-mm-long periodically poled LiNbO(3) crystal in a four-mirror ring cavity. At a pump power of 8.3 W provided by the wavelength-tunable Yb-doped fiber laser, the singly resonant OPO generates 1.9 W of 3200-nm cw idler radiation. The singly resonant OPO was tuned from 1515 to 1633 nm (signal) and from 3057 to 3574 nm (idler) by means of the crystal temperature and poling period. We obtained a wide idler tuning range, from 2980 to 3700 mn, by tuning the wavelength of the fiber laser from 1032 to 1095 nm.

Wide wavelength tuning of an optical parametric oscillator through electro-optic shaping of the gain spectrum.

We present a novel technique for tuning an optical parametric oscillator (OPO) through electro-optically induced shape variations of the parametric gain spectrum in quasi-phase-matched lithium niobate (LN). The diode-pumped, triply resonant continuous-wave OPO is based on a 58-mm-long LN crystal that consists of three equally long sections, the outer sections being periodically poled with a 50% duty cycle. The center section is single-domain material and serves as a tunable phase shifter through the electro-optic effect. By application of a voltage of up to 1230 V, the OPO signal and idler wavelengths are tuned over 102 nm from 1560 to 1660 nm, in good agreement with theory.

Fertility treatment in the forty and older woman.

PURPOSE: To determine the outcomes and logical progression of fertility treatment in women forty years and older using their own oocytes. METHODS: This was a retrospective study in which 401 completed treatment cycles in 152 women aged forty and older were reviewed. RESULTS: Assisted reproductive technology (ART) cycles (n = 58) were reviewed, comprising both in vitro fertilization (IVF) and gamete intrafallopian transfer (GIFT). Intrauterine insemination (IUI) cycles (n = 343) were reviewed, consisting of 38 unstimulated natural cycle-IUI (NC-IUI), 194 clomiphene citrate-IUI (CC-IUI), and 111 injectable gonadotropins-IUI (INJ-IUI) cycles. The live birth rate of 15.5% for ART cycles was significantly higher than the live birth rate of 3.2% seen for all IUI cycles (p = 0.0007). There were no differences among treatment groups in spontaneous abortion, preterm delivery, or ectopic pregnancy rates. CONCLUSIONS: For women > or = 40 years of age who wish to use their own eggs, ART offers the best chances for conception and delivery.

EGO-1 is related to RNA-directed RNA polymerase and functions in germ-line development and RNA interference in C. elegans.

BACKGROUND: Cell-fate determination requires that cells choose between alternative developmental pathways. For example, germ cells in the nematode worm Caenorhabditis elegans choose between mitotic and meiotic division, and between oogenesis and spermatogenesis. Germ-line mitosis depends on a somatic signal that is mediated by a Notch-type signaling pathway. The ego-1 gene was originally identified on the basis of genetic interactions with the receptor in this pathway and was also shown to be required for oogenesis. Here, we provide more insight into the role of ego-1 in germ-line development. RESULTS: We have determined the ego-1 gene structure and the molecular basis of ego-1 alleles. Putative ego-1 null mutants had multiple, previously unreported defects in germ-line development. The ego-1 transcript was found predominantly in the germ line. The predicted EGO-1 protein was found to be related to the tomato RNA-directed RNA polymerase (RdRP) and to Neurospora crassa QDE-1, two proteins implicated in post-transcriptional gene silencing (PTGS). For a number of germ-line-expressed genes, ego-1 mutants were resistant to a form of PTGS called RNA interference. CONCLUSIONS: The ego-1 gene is the first example of a gene encoding an RdRP-related protein with an essential developmental function. The ego-1 gene is also required for a robust response to RNA interference by certain genes. Hence, a protein required for germ-line development in C. elegans may be a component of the RNA interference/PTGS machinery.

Diode-pumped singly resonant continuous-wave optical parametric oscillator with wide continuous tuning of the near-infrared idler wave.

We demonstrate wide, continuous tuning of the single-frequency idler wave of a cw singly resonant optical parametric oscillator (SRO). The SRO consists of a periodically poled LiNbO(3) crystal for quasi-phase matching in a four-mirror signal-resonant ring cavity. The SRO, excited by 2.25 W of 924-nm radiation from an InGaAs diode laser, generates as much as 200 mW of single-frequency 2.1-mum idler radiation. We tune the idler frequency continuously within a range as large as 56 GHz by changing the wavelength of the diode pump laser. The versatility of this continuously tunable single-frequency infrared source is demonstrated by recording of N(2)O rovibrational absorption lines near 2.1 mum.

2.5-GHz repetition-rate singly resonant optical parametric oscillator synchronously pumped by a mode-locked diode oscillator amplifier system.

We report on an optical parametric oscillator (OPO) that is synchronously pumped directly by a diode laser. This laser is an actively mode-locked master-oscillator power-amplifier system that produces 20-ps pulses at 927 nm with a repetition rate of 2.5 GHz and an average power of 0.9 W. The OPO, which is a singly resonant device based on periodically poled lithium niobate, generates 7.8-ps pulses. The OPO threshold is 300 mW of average pump power, and the maximum average idler output power is 78 mW at a wavelength of 2100 nm. By changing the crystal temperature we can wavelength tune the output in the ranges 1530-1737 nm (signal) and 1986-2348 nm (idler). Rapid wavelength tuning of the OPO over 46 nm (signal) and 74 nm (idler) is achieved through tuning the cavity length over 28 microm by use of a piezoelectric transducer.

Singly resonant continuous-wave optical parametric oscillator pumped by a diode laser.

We report on what is believed to be the first singly resonant cw optical parametric oscillator (SRO) that is directly pumped by a diode laser. The SRO consists of a 38-mm-long periodically poled LiNbO(3) crystal in a four-mirror signal-resonant ring cavity. Pumped by 2.5 W of 925-nm diode-laser radiation, the SRO generates 480 mW of single-frequency idler radiation at 2.1mum . The wavelengths of the signal and the idler output are tuned in the ranges of 1.55 to 1.70mum and 2.03 to 2.29mum, respectively, by tuning the wavelength of the diode laser from 924.0 to 925.4 nm.

Periodically poled potassium niobate for second-harmonic generation at 463 nm.

We report on the fabrication and characterization of quasi-phase-matched potassium niobate crystals for second-harmonic generation. Periodic 30-mum -pitch antiparallel ferroelectric domains are fabricated by means of poling in an electrical field. Both birefrigence and periodic phase shift of the generated second harmonic contribute to phase matching when the d(31) nonlinear optical tensor element is used. 3.8 mW of second-harmonic radiation at 463 nm is generated by frequency doubling of the output of master-oscillator power-amplifier diode laser in a 5-mm-long crystal. The measured effective nonlinear coefficient is 3.7pm/V. The measured spectral acceptance bandwidth of 0.25 nm corresponds to the theoretical value.

Diode-pumped continuous-wave widely tunable optical parametric oscillator based on periodically poled lithium tantalate.

We report on a diode-laser pumped cw optical parametric oscillator (OPO) based on quasi-phase-matched periodically poled lithium tantalate. Pumped by the 2.3-W single-frequency, nearly diffraction-limited 925-nm output of an InGaAs diode master-oscillator power amplifier, the pump and signal resonant OPO generates a single-frequency idler wave with an output of as much as 244 mW. The wavelengths of the signal and idler waves are widely tunable in the range 1.55-2.3mum by use of different poling periods (27.3 to 27.9mum) and by variation of the crystal temperature in the range 70-190 degrees C.

trans-2-phenylcyclopropylamine is a substrate for and inactivator of horseradish peroxidase.

Horseradish peroxidase (HRP) is well known for mediating the electron-transfer oxidation of electron-rich aromatic 'donors' such as phenols and anilines, but has not been described to oxidize aliphatic amines. We here confirm the inability of HRP to oxidize typical aliphatic amines, even those which would exist significantly as free bases at the operative pH. In contrast, trans-2-phenylcyclopropylamine (2-PCPA) is both a substrate (turnover product is cinnamaldehyde) and a time-dependent inactivator of HRP. These activities of 2-PCPA are consistent with either a concerted or rapid sequential one-electron-oxidation/ring-opening to give an intermediate capable of covalent binding to the enzyme. 2-PCPA is the first known example of a simple aliphatic amine which serves as a substrate for HRP under turnover conditions.

Haemoprotein-mediated metabolism of enamines and the possible involvement of one-electron oxidations.

1. Microsomal metabolism of 1-benzylpiperidine (1-BP), its cis-2,6-dimethyl (cis-2,6-DMBP), 4,4-dimethyl (4,4-DMBP), and alpha, alpha-dimethyl (alpha, alpha-DMBP) analogues, and phencyclidine (PCP) has been studied to assess the involvement of P450 oxidation of the enamine tautomers of the initial endocyclic iminium metabolites. 2. The selective prevention by cyanide of the metabolite production of 1-benzyl-3-piperidone but not 1-benzyl-3-piperidinol from 1-BP is consistent with the enamine as the source of the 3-one metabolite. 3. The parent amines and particularly the independently prepared iminium species induced a pattern of metabolism-dependent irreversible inactivation of P450 benz-phetamine demethylase activity, consistent with involvement of enamine C-3 oxidation in the inactivation process. 4. Substrate activity of the endocyclic enamines and alpha-aminoketones (presumably the enol-enamine tautomers) for horseradish peroxidase under conditions where simple aliphatic amines display no activity is consistent with metabolic one-electron oxidations of the enamines.

Incidence and pattern of jaundice in healthy breast-fed infants during the first month of life.

The incidence and pattern of jaundice in 155 normal, full-term, breast-fed, white infants was examined. Infants were screened for jaundice on Days 2, 3, 5, 7, 9, 11, and 13 following birth using transcutaneous bilirubinometry (TcB). By Day 3, 49.7% of the infants were classified as jaundiced (> 10 mg/dl). Infants with low TcB indices on Days 2, 3, and 5 never developed jaundice as indicated by elevated TcB indices on Days 7, 9, 11, and 13. Hence, it may be possible to target infants at risk for severe jaundice prior to discharge. The observed rate of 10.3% for breast-milk jaundice (jaundice present at Day 13) is significantly higher than the highest reported rate of 2.4% (z = 6.43, p < .01). Furthermore, the pattern of jaundice in these infants does not appear to have two peaks, indicating that it is not possible to distinguish between exaggerated physiologic jaundice and breast-milk jaundice using TcB.

Transcutaneous bilirubinometer: intermeter reliability.

This study examined intermeter reliability on two transcutaneous bilirubinometers on 30 white prephototherapy infants between 36 and 42 weeks' gestation with birthweights greater than 2500 g. All infants were screened with both meters, on the forehead, within a 5-minute period. Meter readings were taken within 30 minutes following infant heelstick for serum bilirubin. The Pearson correlations between serum bilirubin and jaundice meter measurements were .75 for meter 1 and .76 for meter 2. The correlation between jaundice meter indices from the two meters was .87, leaving 13% of the variance in one meter not accounted for by the correlation with the other meter. An examination of the differences between the two meters revealed that in the upper range (greater than or equal to 16) meter 1 was always higher than meter 2 by, on the average, 2.6 points (SD = 1.3). In readings of 15 or less, the differences between the meters were inconsistent. Additionally, in 16 of 30 cases, the action levels from the two meters led to the same conclusion; in the remaining 14 cases, meter 1 gave a positive reading (indicating the need to determine serum bilirubin) while meter 2 gave an equivocal reading (indicating user discretion in deciding whether serum bilirubin should be determined). These data indicate that each meter should be individually evaluated to determine action indices, and that jaundice meters should not be used interchangeably on the same infant.