Broadband mid-IR frequency comb with CdSiP2 and AgGaS2 from an Er,Tm:Ho fiber laser.

We report on the generation of a 2500 nm bandwidth frequency comb at 6.5 µm central wavelength based on critically phase-matched parametric down-conversion in the nonlinear crystal CdSiP(2) (CSP), driven by a compact Er,Tm:Ho fiber laser. The generated ultra-broadband pulses show a transform-limited duration of 2.3 optical cycles and carry up to 150 pJ of energy at a 100 MHz pulse repetition rate. For comparison, the spectrum generated in AgGaS(2) (AGS) spans from 6.2 to 7.4 µm at full-width at half-maximum (FWHM) with a pulse energy of 3 pJ. A full 3D nonlinear wave propagation code is used for optimization of the noncollinear angle, propagation direction, and crystal thickness.

Fiber chirped pulse amplifier at 2.08 µm emitting 383-fs pulses at 10 nJ and 7 MHz.

An all-polarization maintaining (PM) fiber chirped pulse amplifier system at 2.08 µm based on thulium:holmium codoped gain fibers is reported. An inhouse built oscillator emits pulses at a repetition rate of 7 MHz with a spectral full width at half-maximum (FWHM) bandwidth of 23.5 nm at 2.8 mW average output power. The pulses are temporally stretched and subsequently amplified in a double-stage amplifier setup. The stretched pulses are compressed to 383 fs by use of a Martinez-style setup at an output pulse energy of 10.2 nJ. By neglecting temporal stretching, high peak powers in a single amplifier stage led to Raman soliton formation at 2.3 µm.

All-PM coherent 2.05 µm Thulium/Holmium fiber frequency comb source at 100 MHz with up to 0.5 W average power and pulse duration down to 135 fs.

We report on a dual output all-PM fiber laser system running at 100 MHz repetition rate offering coherent broadband and narrowband pulses centered at 2.05 µm with a spectral FWHM bandwidth of 60 nm and 1.5 nm at up to 360 mW and 500 mW, respectively. The broadband pulses are compressed down to 135 fs. The multi-stage double-clad amplifier based on Tm/Ho codoping is seeded by a supercontinuum light source, spanning from around 1 µm up to 2.4 µm.

An evidence-based mobile decision support system for subaxial cervical spine injury treatment.

Bringing evidence to practice is a key issue in modern medicine. The key barrier to information searching is time. Clinical decision support systems (CDSS) can improve guideline adherence. Mounting evidence exists that mobile CDSS on handheld computers support physicians in delivering appropriate care to their patients. Subaxial cervical spine injuries account for almost half of spine injuries, and a majority of spinal cord injuries. A valid and reliable classification exists, including evidence-based treatment algorithms. A mobile CDSS on this topic was not yet available. We developed and tested an iPhone application based on the Subaxial Injury Classification (SLIC) and 5 evidence-based treatment algorithms for the surgical approach to subaxial cervical spine injuries. The application can be downloaded for free. Users are cordially invited to provide feedback in order to direct further development and evaluation of CDSS for traumatic lesions of the spinal column.

The effect of sacral nerve stimulation on uterine activity: a pilot study.

INTRODUCTION: Sacral nerve stimulation (SNS) is a treatment for consecutive therapy resistant faecal incontinence or constipation. Little is known about the effects of SNS on uterocervical function. Therefore, it is advised to turn off the stimulator during pregnancy or to wait with permanent implantation of the stimulator until family completion. Diagnostic ultrasound provides an, non-invasive, opportunity to study various aspects of uterine activity. The purpose of this pilot study was to assess the influence of SNS on endometrial waves of the nonpregnant uterus by ultrasound recordings. METHOD: Six patients with an implanted SNS were included. Ultrasound recordings were performed with the stimulator turned off and in three stimulation frequencies. Uterine activity is described as wave frequency and wave direction. RESULTS: All three premenopausal patients showed endometrial activity with the stimulator turned off. This activity was maintained with the stimulator turned on in two patients, but disappeared in one patient. All three postmenopausal patients had no endometrial activity with the stimulator turned off. In one patient there was activity with the stimulator turned on at a frequency of 21 Hz. CONCLUSION: We have shown some effect of SNS on uterine activity. In premenopausal women we discovered that SNS seems to exhibit no effect or an inhibitory effect rather than an excitatory effect on uterine activity. Based on the preliminary results of this study, we can not recommend any guidelines for SNS usage during conception and pregnancy. A larger study in premenopausal women with SNS is needed to investigate the significance of these changes.

Endometrial wave-like activity in the non-pregnant uterus.

The non-pregnant uterus shows wave-like activity throughout the menstrual cycle. This uterine activity was first detected using intra-uterine pressure recordings. The use of ultrasound has made it possible to study the movements of the uterus in a non-invasive manner. Throughout the menstrual cycle, several wavelike activity patterns have been described; these patterns change throughout the menstrual cycle and are governed by steroid hormones. An adequate wave pattern seems to be related to successful reproduction in spontaneous cycles and assisted reproduction. Further insight into the phenomenon of endometrial wave-like activity might offer an opportunity to correct abnormal wave patterns and thereby improve pregnancy rates.

Sampling plans for the determination of aflatoxin B1 in large shipments of animal feedstuffs.

Incremental samples (50, 100, and 500 g) were systematically collected from large shipments of copra meal pellets, copra cake, and palm kernel cake to study the distribution of aflatoxin B1 and evaluate adherence of distribution to the model, CV(2)is (EQ) = A + B/Mis (where CVis = coefficient of variation of the true concentration of aflatoxin B1 within the incremental samples; Mis = mass of the incremental samples; and A and B are constants). Also evaluated was the distribution of aflatoxin B1 among 1 kg composite samples, produced both by random combination of existing incremental samples and by collection of 1 kg composite samples (composed of 10 x 100 g increments) from additional batches of copra meal pellets and cottonseed cake. The efficiency of selected sample preparation (grinding and subdivision) procedures was compared, culminating in the development and description of a variety of sampling plans. The coefficient of variation (CV) among incremental samples varied from 0 to 38%, and was independent of incremental sample size. No significant difference (F-test, 5% significance level) was found between the efficacy of 4 sample preparation methods when these methods were applied to the commodities described above. Various sampling plans were evaluated with estimated CVs from 4.0 to 12.5%, for the aflatoxin B1 content of the composite samples.

Three months use of third-generation oral contraceptives does not affect artery wall properties.

In several studies, artery wall properties have been shown to differ between men and women. It has been hypothesized that these differences may result from hormonal influences but, in a previous study, we were unable to detect any influence of the menstrual cycle on artery wall properties. Therefore, we investigated the differences in artery wall properties, if any, between the menstrual cycle and the use of a third-generation oral contraceptive for 3 months. We investigated the right common carotid (CCA) and femoral (CFA) arteries of normotensive young (18-25-y-old) women volunteers (n = 14). The arterial cross-sectional distensibility and compliance coefficients were determined by means of a specially designed ultrasonic wall-tracking device and automatic brachial artery cuff blood-pressure measurements. The menstrual cycles and the cycles during oral contraceptive use (30 microg ethinylestradiol and 75 microg gestodene) were monitored by ultrasonographic evaluation and the assessment of plasma levels of 17beta-oestradiol and progesterone. The distensibility and cross-sectional compliance coefficients of both the CCA and CFA did not differ significantly between the menstrual cycle and the use of oral contraceptives, despite different ovarian hormone levels. Brachial arterial blood pressure was also not affected. We conclude that 3 months use of a third-generation oral contraceptive does not influence the wall properties of peripheral arteries and cannot explain the observed difference between genders. The absence of a rise in blood pressure and the low androgenic profile of this specific oral contraceptive may have contributed to our findings.

Endometrial wave direction switch and the outcome of in vitro fertilization.

OBJECTIVE: To describe endometrial wavelike activity, endometrial thickness and texture in IVF cycles, and to relate them to IVF outcome. To evaluate wave patterns on the day of hCG administration as a predictor of IVF outcome. DESIGN: Ultrasound study. SETTING: University hospital-based infertility clinic. PATIENT(S): Twenty-eight women undergoing IVF. INTERVENTION(S): Ultrasound examinations were performed at five fixed moments (start ovarian stimulation, hCG administration, ovum pickup (OPU), ET, and 7 days after hCG administration) and at three variable moments in the stimulation period in the cycle. The OPU was performed 2 days after hCG administration; ET was performed 2 or 3 days after that. MAIN OUTCOME MEASURE(S): Endometrial wave pattern, thickness, texture, IVF outcome. RESULT(S): Embryo transfer was performed in 22 cycles. In 73% of the cycles a wave direction switch (WDS) from fundus to cervix (FC) to cervix to fundus (CF) occurred before OPU. Eleven (50%) patients became pregnant. Significantly more FC waves persisted until hCG administration in the cycles in which the patients conceived. Endometrial thickness and texture were unrelated to IVF outcome. CONCLUSION(S): Endometrial wave pattern is associated with pregnancy in IVF. The persisting presence of FC waves until hCG administration (a late WDS) predicts a favorable IVF outcome.

Bladder filling reduces femoral artery wall distension and strain: beware of a full bladder!

During a previous study, we noted that the distension and strain of the femoral artery were relatively low when the bladder was full, a situation normally necessary for transabdominal echography. Therefore, in the present study we investigated the influence of bladder filling, if any, on wall properties of the common femoral artery. The results obtained were compared with those obtained in the common carotid artery. The study was performed on the right common carotid and right common femoral arteries of normotensive young (18-35 y) female volunteers (n = 24). Using a specially designed ultrasonic wall-tracking device and automatic brachial artery cuff blood pressure measurements, arterial distension (absolute change in diameter during the cardiac cycle; deltaD), strain (deltaD/D), and cross-sectional distensibility (DC) and compliance (CC) were determined before and after voiding. Distension and strain of the common femoral artery were significantly lower for a full than for an empty bladder. DC and CC were lower when the bladder was filled, but these differences did not reach the level of significance. Blood pressure as measured at the level of the brachial artery and heart rate were not statistically significantly different during a full or an empty bladder. It is concluded that bladder filling affects femoral artery wall properties, an observation that should be kept in mind when performing studies on artery wall properties at this level of the circulation.

Endometrial wavelike activity, endometrial thickness, and ultrasound texture in controlled ovarian hyperstimulation cycles.

OBJECTIVE: To describe endometrial wavelike activity, endometrial thickness, and texture in controlled ovarian hyperstimulation (COH) cycles. DESIGN: Prospective observational ultrasound study. SETTING: University hospital-based infertility clinic. PATIENT(S): Thirty-five COH cycles in 19 women with unexplained infertility. INTERVENTION(S): Transvaginal ultrasound examination was performed throughout COH cycles. Intrauterine insemination was performed after hCG administration. MAIN OUTCOME MEASURE(S): Endometrial wavelike activity, wave frequency, wave velocity, endometrial thickness, and endometrial texture. RESULT(S): Endometrial wavelike activity increased from menstruation to ovulation and decreased in the luteal phase. On day hCG+2, endometrial wave-like activity was observed in all cycles. Waves from cervix to fundus prevailed in the periovulatory phase. Endometrial wavelike activity was related significantly to endometrial thickness at the start of ovarian stimulation and in the luteal phase. Endometrial thickness increased throughout the cycle. Endometrial texture showed periovulatory a triple-line aspect. CONCLUSION(S): In COH cycles, endometrial wavelike activity is more pronounced than in spontaneous cycles. The number of follicles and endometrial wavelike activity were not correlated significantly. This is the first prospective study to provide longitudinal observational evidence that endometrial thickness increases throughout the COH cycle and that a triple line pattern develops.

Velocity of endometrial wavelike activity in spontaneous cycles.

OBJECTIVE: To analyze the velocity and wave intervals of endometrial wavelike activity in spontaneous menstrual cycles. DESIGN: Prospective observational ultrasound (US) evaluation of endometrial wavelike activity. SETTING: University hospital. MAIN OUTCOME MEASURE(S): Endometrial wavelike activity, wave velocity, wave intervals. PATIENT(S): Twenty-three menstrual cycles were evaluated by frequent US investigations in 16 healthy, regularly cycling female volunteers. INTERVENTION(S): Transvaginal US examination of endometrial wavelike activity. RESULT(S): Nineteen cycles proved to be ovulatory. Wave velocity and wave intervals were calculated in waves from fundus to cervix and in waves from cervix to fundus. The velocity of waves from fundus to cervix increased from the midfollicular phase to the late follicular phase. Waves from cervix to fundus showed their highest velocity in the periovulatory period. CONCLUSION(S): Velocity of endometrial wavelike activity reached a peak in the periovulatory phase, whereas the wave intervals were shortest in that phase.

Female sex hormones do not influence arterial wall properties during the normal menstrual cycle.

1. In previous studies, the elastic properties of the common carotid artery were found to differ between men and women. In these studies, however, the phase of the menstrual cycle was not taken into consideration. It was the aim of the present study to investigate the effect of changing ovarian hormone levels during the normal menstrual cycle on the arterial wall properties of female large arteries. 2. We investigated the elastic right common carotid artery and the muscular right common femoral artery of normotensive young (18-35 years) female subjects (n = 12). The arterial distensibility and cross-sectional compliance coefficients were determined by the use of a specially designed ultrasonic wall-tracking device and measurements of automatic brachial artery cuff blood pressure. The phase of the menstrual cycle was assessed by ultrasonographic evaluation and measurement of 17 beta-oestradiol and progesterone blood plasma levels. 3. The distensibility coefficient and the cross-sectional compliance coefficient of both the common carotid and the common femoral artery did not change significantly during the normal menstrual cycle despite evidently changing ovarian hormone levels. 4. We conclude that the menstrual cycle does not influence the arterial wall properties of either the elastic common carotid artery or the muscular common femoral artery.

Relation between endometrial wavelike activity and fecundability in spontaneous cycles.

OBJECTIVE: To determine whether endometrial activity is related to the occurrence of pregnancy in spontaneous menstrual cycles. DESIGN: Prospective observational ultrasound evaluation of endometrial activity during fertility screening cycles. SETTING: University hospital-based infertility clinic. PATIENT(S): Fifty-nine fertility screening cycles (ultrasound monitoring of follicle growth and ovulation, postcoital test, semen analysis, midluteal P, Chlamydia antibody determination, and tubal patency testing) were performed in 47 couples complaining of infertility. In 33 couples (37 cycles), no fertility impairing factors were found. Endometrial activity was analyzed in these cycles. INTERVENTION(S): Ultrasound examination was performed transvaginally throughout the cycle. MAIN OUTCOME MEASURE(S): Endometrial activity, wave pattern, pregnancy. RESULTS(S): Nine women conceived within the cycle studied. Conception cycles showed less-activity compared with nonconception cycles. Endometrial wavelike activity increased throughout the follicular phase and decreased after ovulation in conception and nonconception cycles. CONCLUSION(S): Endometrial activity is related to fecundability in a spontaneous cycle.

Doppler ultrasonography in suspected intrauterine growth retardation: a randomized clinical trial.

A randomized clinical trial was performed to test the hypothesis that if suspected intrauterine growth retardation (IUGR) is associated with normal umbilical artery Doppler ultrasound findings, hospitalization can safely be avoided. One hundred and fifty women with singleton pregnancies and suspected IUGR were randomized between an intervention (n = 74) and a control group (n = 76). In the intervention group, clinicians were strongly requested not to hospitalize for suspected IUGR if the Doppler findings were normal. In the control group, the Doppler results were not revealed and the participants received the standard management for suspected IUGR. Endpoints of the trial were: costs in terms of hospitalization, perinatal outcome, neurological development, and postnatal growth. Duration of hospitalization was significantly shorter in the intervention group than in the control group. Contrary to expectations, the hospitalization rate during pregnancy in the intervention group was not below that of the control group. This negative finding was partly due to the admission of patients in the intervention group despite their normal Doppler results. Moreover, the trial might have induced a more critical attitude towards hospitalization in suspected IUGR, decreasing admission in the control group. No clear differences were found in perinatal outcome, neurological development, or postnatal growth. The results suggest that normal umbilical artery Doppler findings in suspected cases of IUGR justify outpatient management.

Subendometrial contractions in the nonpregnant uterus: an ultrasound study.

Endometrial wavelike activity was studied by ultrasound, throughout 19 ovulatory cycles in 16 healthy female volunteers. Analysis was focused on the presence of endometrial activity and the wave types. Five activity patterns were distinguished, which varied throughout the cycle. Endometrial activity was most striking during the periovulatory phase.

Endometrial wavelike movements during the menstrual cycle.

OBJECTIVE: To qualify and quantify endometrial waves in regularly cycling women. DESIGN: A prospective transvaginal ultrasound study was performed throughout 23 cycles of 16 healthy women. Wave type and wave frequency were evaluated. SETTING: Normal human volunteers in an academic research environment. PATIENTS: Sixteen healthy regularly cycling women. RESULTS: Of 23 cycles, 19 proved to be ovulatory. Five types of endometrial waves could be distinguished. Waves from cervix to fundus and opposing waves were seen predominantly periovulatorily. Waves from fundus to cervix were absent in the postovulatory phase. Endometrial wavelike activity was most pronounced in the periovulatory phase. CONCLUSIONS: Standardized qualification and quantification of endometrial waves, as described in this study, might shed new light on the underlying mechanisms in selected cases of hitherto unexplained subfertility.

Routine clinical policy and application of Doppler measurements in suspected intrauterine growth retardation in university hospitals in The Netherlands.

Suspected intrauterine growth retardation is a clinical problem with financial consequences, as it can lead to costly, in-hospital fetal monitoring. At present, no prospective 'gold standard' for growth retardation exists. Hence, a proportion of the fetuses suspected are likely to be genetically small, in which case hospitalization is superfluous. Doppler ultrasound measurements might be applied to differentiate between growth retardation and genetically based smallness. Before the diagnostic effectiveness of Doppler ultrasound can be evaluated, however, the magnitude of the problem of suspected intrauterine growth retardation, or what it is experienced to be, must be known. The occurrence of suspected intrauterine growth retardation, routine clinical policy, and use of Doppler ultrasound techniques were assessed by a questionnaire among obstetricians in the university hospitals in The Netherlands. Of the obstetricians approached, 81% responded (59/73). Intrauterine growth retardation was defined mainly by a lag in fundal height of at least 3 weeks. It is suspected in about 11% of singleton pregnancies. An estimated 70% of those suspected of growth retardation are hospitalised. Fewer than half of the respondents thought Doppler ultrasound measurements an asset to antenatal diagnosis. Five of the eight university hospital clinics used Doppler measurements in clinical decision making. Sixty percent of responding obstetricians were of the opinion that there was a 'routine clinical policy' in suspected intrauterine growth retardation.

Variation in early fetal growth.

OBJECTIVE: To obtain more information on interindividual variation in early fetal growth by using early fetal ultrasound parameters. DESIGN AND SUBJECTS: Individual fetal growth was assessed prospectively in 109 pregnancies by serial ultrasound measurements of CRL and BPD. From the resulting biometry data, individual CRL and BPD growth curves for each fetus were constructed and compared. RESULTS: A high correlation was found between growth rate and the start of growth of CRL and BPD, r = 0.79 and r = 0.84, respectively. CONCLUSION: The high correlation between growth rate and the start of growth of CRL and BPD might imply that a fetus with an impeded start of growth generally has a higher growth rate. This could be called an early pregnancy 'catch-up growth'. This interindividual variation of starting time and fetal growth rate may influence the assessment of gestational age in early pregnancy, if a CRL-curve obtained from cross-sectional measurements is used as a reference. BPD seems to be a more constant parameter with less variation in growth rate.