Cs Frequency Research Articles

Assessment of the frequency of cesarean section according to the criteria of M. Robson in the Regional perinatal center №1 of Turkestan region

Objective. To identify and analyze the groups of women who contribute the greatest and least to the frequency of caesarean sections in general. Conducting an assessment of the frequency of caesarean sections in the Regional Perinatal Center №1 of the Turkestan region according to the classification of M. Robson.Materials and methods. We conducted a retrospective analysis of the history of 5286 births in the Regional Perinatal Center No. 1. The history of childbirth of women who gave birth in 2022 was taken into account. According to the history of each birth to complete the table: method of delivery (delivery through the birth canal, caesarean section); parity (first time , repeated); number of fetuses (one, two, three or more); delivery period (up to 37 weeks., 37-40 weeks., 41-42 or more); type of fetal malformation (head, pelvis, transverse/ oblique); induction of labor (induction was carried out, induction was not carried out); spontaneous childbirth; the number of caesarean sections in the history (one or more) was taken into account.Results and discussion. The group contributed the most to the total CS frequency were 5 groups – with a history of one or more CSs, one fetal head arrival, ≥37 weeks – 24.1%; the group contributed the least to the total CS frequency was 9 groups – single fetal pregnancy, women with a horizontal or oblique fetal position, including women with a history of one or more CSs – 2.2%.Conclusion. The largest share of the group in the total frequency of CSwas Group 5 – 22.1% of all births, 888 (75.9%) of 1,170 women in this group underwent surgery, all pregnant women with scars on the uterus ; group 9 – 0.7% of births accounted for the smallest share of the group in the total frequency of CS, 100% of 38 women gave birth with CS.

Evolution in caesarean section practices in North Kivu: Impact of caregiver training.

A caesarean section is a major obstetric procedure that can save the life of mother and child. Its purpose is to protect the mother's health from the complications of childbirth and to protect the baby's health. In sub-Saharan Africa (SSA), there are major inequalities in access to caesarean sections and significant variations in practices to determine the indications for the procedure. Periodic analyses of maternal deaths have shown that more than half of maternal and new born deaths are due to suboptimal care and are therefore potentially preventable. The objective of our study is to assess the impact of health staff training under the PADISS project (to support the health system's integrated development) on the quality of CS procedures in North Kivu, by comparing two periods. The populations compared were recruited from the referral hospitals in North Kivu, DRC (Democratic Republic of Congo). The first (group 1) was made up of patient files studied retrospectively for the period from 01/11/2013 to 01/01/2016. The second group (group 2), studied prospectively, comprised patient files from June 2019 to January 2020. Obstetric, maternal and foetal data were compared. Statistical analyses were performed using STATA/IC 15.0 for Windows. Univariate and multiple logistic regression was performed to determine which characteristics are associated with maternal and perinatal morbidity and mortality. A p value < 0.05 was considered statistically significant. CS frequency was approximately 17% in both study periods. We observed a CS frequency of about 34% at North Kivu provincial hospital for the two populations studied. The main indications for CS were dystocia, foetal distress and scarred uterus for both populations. In the population studied prospectively, after the implementation of health staff training, there were fewer incidence rate of dystocia, foetal distress and neonatal death, a more complete patient record, shorter hospital stay, and fewer blood transfusions but more incidence rate of scarred uterus, post-operative complications and low birth weight. Intervention had no statistically significant impact on low birth weight (OR = 1.9, p = 0.13), on neonatal mortality (OR = 0.69, p = 0.21). Our study shows a decrease in neonatal deaths, dystocia and foetal distress, but an increase in post-operative complications, maternal deaths and cases of scarred uterus and low birth weight. However, multiple logistic regression did no support the conclusion.

Enhancing the frequency stability of national time scale using EMD

Almost all time keeping laboratories maintain the 5071A Cesium (Cs) frequency standard for generating their national time scales. The frequency stability of this standard is limited by different types of noise, especially the White Frequency Modulation noise. These noise types affect the stability of the resultant average Time Scale (TS). Kalman Filter (KF) is still applied until now within the time scale algorithm for de-noising and predicting improved resultant TS frequency stability. But, this method is very complicated and is based on difficult estimation techniques. In 2013, the Empirical Mode Decomposition (EMD) technique was applied for the first time on Cs atomic clock signal de-noising and frequency prediction. In this paper, the EMD technique is embedded in the TS generation algorithm for studying its effect on the stability of the resultant TS. Results show that the frequency stability of the resultant TS is improved for averaging times up to nearly 40 days due to EMD. These results are verified by comparing the effect of the EMD to that of the KF on the resultant TS frequency stability. Results show that the frequency stability of the resultant average TS is improved due to using EMD or KF for Cs clock signal de-noising for averaging times up to nearly 40 days. In addition, EMD is found to be more effective and simpler than the complicated KF.

Teacher's code-switching and bilingual children's heritage language learning and cognitive switching flexibility.

To code-switch or not to code-switch? This is a dilemma for many bilingual language teachers. In this study, the influence of teachers' CS on bilingual children's language and cognitive development is explored within heritage language (HL) classes in Singapore. Specifically, the relationship between children's language output, vocabulary development, and cognitive flexibility to teachers' classroom CS behavior, is examined within 20 preschool HL classrooms (10 Mandarin, 6 Malay, and 4 Tamil). Teachers' and children's utterances were recorded, transcribed, and analyzed for CS frequency and type (i.e., inter-sentential, intra-sentential). 173 students were assessed with receptive vocabulary and dimensional card sort tasks, and their vocabulary and cognitive switching scores assessed using correlational and mixed effects analyses. Results show that inter-sentential and intra-sentential CS frequency is positively and significantly related to children's intra-sentential CS frequency. Overall, findings revealed that teachers code-switched habitually more often than for instructional purposes. Neither inter-sentential nor intra-sentential CS was significantly related to children's development in HL vocabulary, and intra-sentential CS was found to positively and significantly relate to children's growth in cognitive flexibility. These findings reveal the multi-faceted impact of teacher's CS on children's early development.

Sensitivity to electron-to-proton mass ratio variation from 12C2H2 rovibrational transitions to v1 + v3 and v1 + v2 + v4 + v5 interacting levels

Calculations of the sensitivity to a variation of the electron-to-proton mass ratio μ for 12C2H2 transitions of the v1+v3 and v1+v2+v4+v5 bands in the spectral region at 1.5μm are presented. They account for the Fermi and l-type rotation and vibration resonances of the excited states. The frequency splittings between near resonant transitions, arising from a cancellation of effective rotational intervals with frequency shifts associated to the vibrational band origin, the anharmonicity and the rotation-vibration interactions, have sensitivity coefficients to a variation of μ of both signs in the range of 10–103. The measurements of temporal drifts of frequency splittings against the Cs frequency standard have the potential to better constrain a variation of μ comparing to that of other fundamental constants. The systematic frequency shifts for frequency splittings are discussed for experimental setups based on intracavity saturated absorption spectroscopy and the constraint of a measurement of a fractional variation of μ is projected at 10−10 level.

Measurement of rubidium ground-state hyperfine transition frequency using atomic fountains

The results of precision measurements of the 87Rb ground-state hyperfine transition frequency, which were conducted at NPL from 2009 to 2013, are reported. The resulting frequency, measured using NPL’s Cs and Rb atomic frequency standards, demonstrates reasonable agreement with the most recent measurements reported by LNE-SYRTE.

Detection of an inhibitory cortical gradient underlying peak shift in learning: A neural basis for a false memory

Experience often does not produce veridical memory. Understanding false attribution of events constitutes an important problem in memory research. “Peak shift” is a well-characterized, controllable phenomenon in which human and animal subjects that receive reinforcement associated with one sensory stimulus later respond maximally to another stimulus in post-training stimulus generalization tests. Peak shift ordinarily develops in discrimination learning (reinforced CS+, unreinforced CS−) and has long been attributed to the interaction of an excitatory gradient centered on the CS+ and an inhibitory gradient centered on the CS−; the shift is away from the CS−. In contrast, we have obtained peak shifts during single tone frequency training, using stimulation of the cholinergic nucleus basalis (NB) to implant behavioral memory into the rat. As we also recorded cortical activity, we took the opportunity to investigate the possible existence of a neural frequency gradient that could account for behavioral peak shift. Behavioral frequency generalization gradients (FGGs, interruption of ongoing respiration) were determined twice before training while evoked potentials were recorded from the primary auditory cortex (A1), to obtain a baseline gradient of “habituatory” neural decrement. A post-training behavioral FGG obtained 24h after three daily sessions of a single tone paired with NB stimulation (200trials/day) revealed a peak shift. The peak of the FGG was at a frequency lower than the CS while the cortical inhibitory gradient was at a frequency higher than the CS frequency. Further analysis indicated that the frequency location and magnitude of the gradient could account for the behavioral peak shift. These results provide a neural basis for a systematic case of memory misattribution and may provide an animal model for the study of the neural bases of a type of “false memory”.

Calculations of the infrared and Raman spectra of simple thiols and thiol–water complexes

AbstractThe frequencies and intensities of infrared and Raman spectra of H2S, CH3SH, CH3CH2SH, and CH2CHCH2SH, isolated and complexed with one water molecule acting as a proton acceptor were calculated at the ab initio and density functional level. Hartree‐Fock, MP2 and CCSD(T) methods were used both for the geometry optimization and spectra calculations at the molecular orbital level. The B3LYP, PBE0, and M06 exchange‐correlation potentials were employed to calculate the same properties at the DFT level. Both Pople basis sets, 6‐31+G(d) and 6‐311++G(3df,2pd), and Dunning basis sets, aug‐cc‐pVTZ and aug‐cc‐pVQZ, were used. SH and CS frequency shifts upon water complexation were studied, and a discussion is performed on the expected relation between the CH and CS Raman activities, in view of their usefulness for studies in protein chemistry. Scaling factors for the vibrational frequencies were obtained for all the combination of methods and basis sets, and shown to be completely similar to the ones present in the literature when available. Scaling factors for the M06 method are presented for the first time with these basis sets. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010

Tone-Specific and Nonspecific Plasticity of Inferior Colliculus Elicited by Pseudo-Conditioning: Role of Acetylcholine and Auditory and Somatosensory Cortices

Experience-dependent plasticity in the central sensory systems depends on activation of both the sensory and neuromodulatory systems. Sensitization or nonspecific augmentation of central auditory neurons elicited by pseudo-conditioning with unpaired conditioning tonal (CS) and unconditioned electric leg (US) stimuli is quite different from tone-specific plasticity, called best frequency (BF) shifts, of the neurons elicited by auditory fear conditioning with paired CS and US. Therefore the neural circuits eliciting the nonspecific augmentation must be different from that eliciting the BF shifts. We first examined plastic changes in the response properties of collicular neurons of the big brown bat elicited by pseudo-conditioning and found that it elicited prominent nonspecific augmentation-an auditory response increase, a frequency-tuning broadening, and a threshold decreas-and that, in addition, it elicited a small short-lasting BF shift only when the CS frequency was 5 kHz lower than the BF of a recorded neuron. We examined the role of acetylcholine and the auditory and somatosensory cortices in these collicular changes. The development of the nonspecific augmentation was affected little by a muscarinic acetylcholine receptor antagonist applied to the inferior colliculus and by a GABA(A) receptor agonist applied to the auditory or somatosensory cortex. However, these drugs abolished the small short-lasting BF shift as they abolished the large long-lasting cortical and short-lasting collicular BF shifts elicited by the conditioning. These results indicate that, different from the BF shift, the nonspecific augmentation of the inferior colliculus depends on neither the cholinergic neuromodulator nor the auditory and somatosensory cortices.

Investigations on continuous and pulsed interrogation for a CPT atomic clock

We investigated the influence of some critical parameters and operating conditions such as cell temperature, laser intensity, and interrogation technique affecting the performances of a gas cell Cs frequency standard based on coherent population trapping (CPT). Thanks to an original experimental setup, the atoms can be trapped in the dark state and interrogated using continuous wave (CW) or pulsed coherent optical radiations. Using a double-lambda scheme, a signal contrast as high as 52% has been measured in the continuous regime for an optimum cell temperature of 35 degrees C. Compared with the conventional continuous CPT interrogation, the pulsed interrogation technique reduces the light shift by a factor of 300 and allowed it to reach high-frequency stability for higher laser intensities. The frequency stability has been measured to be 9 x 10(-13) for a 1 s integration time. Main noise contributions limiting the short-term and medium-term frequency stability are reviewed and estimated.

Absolute frequency measurement of the magnesium intercombination transitionS01→P13

We report on a frequency measurement of the $(3{s}^{2})^{1}S_{0}\ensuremath{\rightarrow}(3s3p)^{3}P_{1}$ clock transition of $^{24}\mathrm{Mg}$ on a thermal atomic beam. The intercombination transition has been referenced to a portable primary Cs frequency standard with the help of a femtosecond fiber laser frequency comb. The achieved uncertainty is $2.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}$, which corresponds to an increase in accuracy of six orders of magnitude compared to previous results. The measured frequency value permits the calculation of several other optical transitions from $^{1}S_{0}$ to the $^{3}P_{J}$-level system for $^{24}\mathrm{Mg}$, $^{25}\mathrm{Mg}$, and $^{26}\mathrm{Mg}$. We describe in detail the components of our optical frequency standard such as the stabilized spectroscopy laser, the atomic beam apparatus used for Ramsey-Bord\'e interferometry, and the frequency comb generator and discuss the uncertainty contributions to our measurement including the first- and second-order Doppler effect. An upper limit of $3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}$ in $1\phantom{\rule{0.3em}{0ex}}\mathrm{s}$ for the short-term instability of our optical frequency standard was determined by comparison with a quartz oscillator disciplined to the signal received from the global positioning system (GPS).

Specific auditory memory induced by nucleus basalis stimulation depends on intrinsic acetylcholine

Although the cholinergic system has long been implicated in the formation of memory, there had been no direct demonstration that activation of this system can actually induce specific behavioral memory. We have evaluated the “cholinergic-memory” hypothesis by pairing a tone with stimulation of the nucleus basalis (NB), which provides acetylcholine to the cerebral cortex. We found that such pairing induces behaviorally-validated auditory memory. NB-induced memory has the key features of natural memory: it is associative, highly-specific and rapidly induced. Moreover, the level of NB stimulation controls the amount of detail in memory about the tonal conditioned stimulus. While consistent with the hypothesis that properly-timed release of acetylcholine (ACh) during natural learning is sufficient to induce memory, pharmacological evidence has been lacking. This study asked whether scopolamine, a muscarinic antagonist, impairs or prevents the formation of NB-induced memory. Adult male rats were first tested for responses (disruption of ongoing respiration) to tones (1–15 kHz), constituting a pre-training behavioral frequency generalization gradient (BFGG). Then, they received a single session of 200 trials of a tone (8.00 kHz, 70 dB, 2 s) paired with electrical stimulation of the NB (100 Hz, 0.2 s). Immediately after training, they received either scopolamine (1.0 mg/kg, i.p.) or saline. Twenty-four hours later, they were tested for specific memory by obtaining post-training BFGGs. The saline group developed CS-specific memory, manifested by maximum increase in response specific to the CS frequency band. In contrast, the scopolamine group exhibited no such memory. These findings indicate that NB-induced specific associative behavioral memory requires the action of intrinsic acetylcholine at muscarinic receptors, and supports the hypothesis that natural memory formation engages the nucleus basalis and muscarinic receptors.

Motivationally neutral stimulation of the nucleus basalis induces specific behavioral memory

The cholinergic system has been implicated in learning and memory. The nucleus basalis (NB) provides acetylcholine (ACh) to the cerebral cortex. Pairing a tone with NB stimulation (NBstm) to alter cortical state induces both associative specific tuning plasticity in the primary auditory cortex (A1) and associative specific auditory behavioral memory. NB-induced memory has major features of natural memory that is induced by pairing a tone with motivational reinforcers, e.g., food or shock, suggesting that the cholinergic system may be a “final common pathway” whose activation promotes memory storage. Alternatively, NB stimulation might itself be motivationally significant, either rewarding or punishing. To investigate these alternatives, adult male rats (n=7) first formed a specific NB-induced memory (CS=8.0kHz, 2.0s paired with NBstm, ISI=1.8s, 200 trials), validated by post-training (24h) frequency generalization gradients (1–15kHz) of respiration interruption that were specific to the CS frequency. Thereafter, they received the same level of NBstm that had induced memory, while confined to one quadrant of an arena, and later tested for place-preference, i.e., avoidance or seeking of the quadrant of NBstm. This NBstm group exhibited neither preference for nor against the stimulated quadrant, compared to sham-operated subjects (n=7). The findings indicate that specific associative memory can be induced by direct activation of the NB without detectable motivational effects of NB stimulation. These results are concordant with a memory-promoting role for the nucleus basalis that places it “downstream” of motivational systems, which activate it to initiate the storage of the current state of its cholinergic targets.

Long-Term Consolidation and Retention of Learning-Induced Tuning Plasticity in the Auditory Cortex of the Guinea Pig

The major goal of this study was to determine whether classical conditioning produces long-term neural consolidation of frequency tuning plasticity in the auditory cortex. Local field potentials (LFPs) were obtained from chronically implanted adult male Hartley guinea pigs that were divided into conditioning (n = 4) and sensitization control (n = 3) groups. Tuning functions were determined in awake subjects for average LFPs (∼0.4 to 36.0 kHz, −20 to 80 dB) immediately before training as well as 1 h and 1, 3, 7, and 10 days after training; sensitization subjects did not have a 10-day retention test. Conditioning consisted of a single session of 30 to 45 trials of a 6-s tone (CS, 70 dB) that was not the best frequency (BF, peak of a tuning curve), followed by a brief leg shock (US) at CS offset. Sensitization control animals received the same density of CS and US presentations unpaired. Heart rate recordings showed that the conditioning group developed conditioned bradycardia, whereas the sensitization control group did not. Local field potentials in the conditioning group, but not in the sensitization group, developed tuning plasticity. The ratio of responses to the CS frequency versus the BF were increased 1 h after training, and this increase was retained for the 10-day period of the study. Both tuning plasticity and retention were observed across stimulus levels (10–80 dB). Most noteworthy, tuning plasticity exhibited consolidation (i.e., developed greater CS-specific effects across retention periods), attaining asymptote at 3 days. The findings indicate that LFPs in the auditory cortex have three cardinal features of behavioral memory: associative tuning plasticity, long-term retention, and long-term consolidation. Potential cellular and subcellular mechanisms of LFP tuning plasticity and long-term consolidation are discussed.

Research Note On the frequency of the CS (J: 2$\rightarrow$1) and (J: 5$\rightarrow$4) transitions

While conducting high signal-to-noise ratio (SNR) observations of multiple transitions and different isotopomers of CS, SO and CO towards L183 (also known as L134N), we found that the CS ( J : 2$\rightarrow$1) line frequency established by Kuiper et al. ([CITE]) during observations towards L1498 was in disagreement with our observations. We have consequently repeated their observations towards that object, but in a slightly different manner by observing simultaneously the CS ( J : 2$\rightarrow$1) line at 98 GHz and the CCS ( J N : 8$_7\rightarrow7_6$) line at 94 GHz with the same telescope and the same receivers therefore eliminating the possibility of errors associated with either software or hardware. We found that our L183 data was best described with the standard frequency of 97 980.95 MHz. We also found a real difference in the velocity position of the CS and CCS peaks in L1498, but one only half that reported by Kuiper et al. ([CITE]). Most importantly, we have established that the L1498 cloud is not well-suited to set the CS ( J : 2$\rightarrow$1) frequency despite the exceptional narrowness of the lines. The CS ( J : 2$\rightarrow$1) line shape is far from Gaussian and suffers from strong effects, due either to large-scale movements (infall and/or rotation), or to self-absorption, or both. These results and other works (Lemme et al. [CITE]; Lee et al. [CITE]) have convinced us that these observations are consistent with the standard CS ( J : 2$\rightarrow$1) line frequency. We also checked the C 34 S ( J : 2$\rightarrow$1) and the CS ( J : 5$\rightarrow$4) transitions and found a major discrepancy for the latter with the JPL catalogue. Finally, CS transitions have been recently re-measured in the laboratory by Gottlieb et al. ([CITE]) with high precision and are found to be consistent with our interpretation.

A microwave exciter for Cs frequency standards based on a sapphire-loaded cavity oscillator.

A low noise and highly stable microwave exciter system has been built for Cs atomic frequency standards using a tunable sapphire-loaded cavity oscillator (SLCO), which works at room temperature. This paper discusses the successful implementation of a control system for locking the SLCO to a long-term reference signal and reports an upper limit of the achieved frequency tracking error 6 x 10(-15) at tau = 1 s.

Accuracy evaluation of the optically pumped Cs frequency standard at NRLM

The optically pumped cesium (Cs) frequency standard at the National Research Laboratory of Metrology, Ibaraki, Japan (NRLM), NRLM-4, was modified in various ways in order to improve frequency stability and accuracy, We determined the frequency stability by comparing the phase with that of a hydrogen maser: the Allan deviation was /spl sigma//sub y/(/spl tau/)=5/spl times/10/sup -13///spl radic//spl tau/. We estimated the frequency corrections and uncertainties due to various sources, and the total uncertainty was found to be 2.9/spl times/10/sup -14/. The frequency difference between NRLM-4 and the international atomic time (TAI) was also measured.

High homogeneity solenoidal magnet for cesium frequency standard

In Cs frequency standards a zone of highly uniform magnetic flux density, lower in value of 0.1 T, is required. The magnetic homogeneity value is tied to the overall accuracy of the standard and, for an accuracy of 10/sup -14/, a design value 1 p.p.m. is required. For this purpose a resistive solenoid 700 mm long with a bore radius of 32.5 mm has been designed and built. This paper reports the design process, the measurements on the manufactured magnet and the shimming strategy used to reach the homogeneity target.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Vibrational spectra and structure of 3,6-dithiaoctane-1,8-diol

IR and Raman spectra of 3,6-dithiaoctane-1,8-diol in the solid, melt and solution were studied. The structure of the molecule is discussed on the basis of the spectral data and the results of the normal coordinate analysis for eight conformers due to rotation around the central CC bond. In crystal the structure with a trans conformation of the central moiety and with a relatively strong intermolecular OH ··· O hydrogen bond exists. In the liquid phase, the molecule has a gauche conformation with respect to the central CC bond with an intramolecular hydrogen bond, which seems most likely to be of the OH ··· S type. The ν CS frequency region (600–800 cm −1) is a sensitive indicator for determining of the conformation towards the central CC bond.

Development of a frequency-stabilized compact light source for an optically pumped Cs frequency standard

A compact light source using a laser diode, whose frequency was stabilized to a saturated absorption spectrum of the Cs-D2 line (λ=852 nm), was developed for use of an optically pumped cesium frequency standard. The temperature of the laser diode was stabilized within 0.1 mK by two stages of feedback systems. Frequency stabilization to the saturated absorption spectrum was performed by modulating the injection current to the laser diode with 100 kHz. The frequency stability was measured by taking the beat of two light sources thus stabilized, and it was estimated to be 4.4×10−11(15 kHz) at an averaging time of 600 ms.