Measurements of All-Particle Energy Spectrum and Mean Logarithmic Mass of Cosmic Rays from 0.3 to 30 PeV with LHAASO-KM2A

We present the measurements of all-particle energy spectrum and mean logarithmic mass of cosmic rays in the energy range of 0.3-30 PeV using data collected from LHAASO-KM2A between September 2021 and December 2022, which is based on a nearly composition-independent energy reconstruction method, achieving unprecedented accuracy. Our analysis reveals the position of the knee at 3.67±0.05±0.15  PeV. Below the knee, the spectral index is found to be -2.7413±0.0004±0.0050, while above the knee, it is -3.128±0.005±0.027, with the sharpness of the transition measured with a statistical error of 2%. The mean logarithmic mass of cosmic rays is almost heavier than helium in the whole measured energy range. It decreases from 1.7 at 0.3 PeV to 1.3 at 3 PeV, representing a 24% decline following a power law with an index of -0.1200±0.0003±0.0341. This is equivalent to an increase in abundance of light components. Above the knee, the mean logarithmic mass exhibits a power law trend towards heavier components, which is reversal to the behavior observed in the all-particle energy spectrum. Additionally, the knee position and the change in power-law index are approximately the same. These findings suggest that the knee observed in the all-particle spectrum corresponds to the knee of the light component, rather than the medium-heavy components.

[Genotype-phenotype analysis of Fabry disease caused by GLA gene variation in a pedigree]

Objective: To investigate the clinical phenotype and genetic characteristics of patients with Fabry disease caused by a GLA variant, IVS4+919G>A. Methods: It was a prospective study. Fabry disease screening was conducted among high-risk population in Ninghai from October 2021 to August 2023. Those children with decreased α-galactosidase enzyme activity<2.40 μmol/(L·h) or elavated Lyso-GL-3 level>1.10 μg/L in dried blood spot (DBS) method underwent GLA genetic testing for diagnosis confirmation. Meanwhile, family screening was carried out. A proband and his family members diagnosed with Fabry disease were research subjects. The clinical and genetic characteristics of patients with Fabry disease caused by the GLA variant (IVS4+919G>A) were analyzed. Results: The female proband aged 9.8 years with pain in both lower limbs as the initial symptom was found to have a heterozygous GLA variant IVS4+919G>A among 102 patients. In family screening, there were 4 family members (proband's father, elder sister, elder male cousin and elder female cousin) with Fabry disease and a family member (proband's fifth aunt) with a GLA variant. Among these 4 diagnosed family members, the elder male cousin of the proband, a boy aged 13.2 years had a heterozygous GLA variant, IVS4+919G>A with intermittent pain in both lower limbs as the initial symptom. The proband's father had knee joint pain. The proband's elder sister had decreased vision and his elder female cousin had no obvious symptoms. The proband's fifth aunt with a GLA variant had decreased vision. Conclusions: High-risk screening in children and family screening are helpful for early diagnosis and treatment of Fabry disease. Neuropathic pain may be a early symptom in children with Fabry disease caused by the GLA variant, IVS4+919G>A.

Measurement of Ultra-High-Energy Diffuse Gamma-Ray Emission of the Galactic Plane from 10 TeV to 1 PeV with LHAASO-KM2A

The diffuse Galactic γ-ray emission, mainly produced via interactions between cosmic rays and the interstellar medium and/or radiation field, is a very important probe of the distribution, propagation, and interaction of cosmic rays in the Milky Way. In this Letter, we report the measurements of diffuse γ rays from the Galactic plane between 10 TeV and 1 PeV energies, with the square kilometer array of the Large High Altitude Air Shower Observatory (LHAASO). Diffuse emissions from the inner (15°10  TeV). The energy spectrum in the inner Galaxy regions can be described by a power-law function with an index of -2.99±0.04, which is different from the curved spectrum as expected from hadronic interactions between locally measured cosmic rays and the line-of-sight integrated gas content. Furthermore, the measured flux is higher by a factor of ∼3 than the prediction. A similar spectrum with an index of -2.99±0.07 is found in the outer Galaxy region, and the absolute flux for 10≲E≲60  TeV is again higher than the prediction for hadronic cosmic ray interactions. The latitude distributions of the diffuse emission are consistent with the gas distribution, while the longitude distributions show clear deviation from the gas distribution. The LHAASO measurements imply that either additional emission sources exist or cosmic ray intensities have spatial variations.

A tera-electron volt afterglow from a narrow jet in an extremely bright gamma-ray burst

Some gamma-ray bursts (GRBs) have a tera-electron volt (TeV) afterglow, but the early onset of this has not been observed. We report observations with the Large High Altitude Air Shower Observatory of the bright GRB 221009A, which serendipitously occurred within the instrument field of view. More than 64,000 photons >0.2 TeV were detected within the first 3000 seconds. The TeV flux began several minutes after the GRB trigger, then rose to a peak about 10 seconds later. This was followed by a decay phase, which became more rapid ~650 seconds after the peak. We interpret the emission using a model of a relativistic jet with half-opening angle ~0.8°. This is consistent with the core of a structured jet and could explain the high isotropic energy of this GRB.

[Progress in omics research and preclinical models of gallbladder cancer]

Gallbladder cancer(GBC)is one common type of bile tract cancers with poor prognosis. This review summarizes the recent development of studies about somatic mutation, molecular subtype, microenvironment heterogeneity, organoid, orthotopic model, patient-derived xenograft and clinical translation on GBC in aspects of genomic,transcriptome,single cell omics and clinical translation. We expect this review will provide new ideas on dissecting molecular mechanisms underlying the development and emerging chemoresistance of GBC following therapy and promote GBC precision medicine.

Constraints on Heavy Decaying Dark Matter from 570 Days of LHAASO Observations

The kilometer square array (KM2A) of the large high altitude air shower observatory (LHAASO) aims at surveying the northern γ-ray sky at energies above 10 TeV with unprecedented sensitivity. γ-ray observations have long been one of the most powerful tools for dark matter searches, as, e.g., high-energy γ rays could be produced by the decays of heavy dark matter particles. In this Letter, we present the first dark matter analysis with LHAASO-KM2A, using the first 340 days of data from 1/2-KM2A and 230 days of data from 3/4-KM2A. Several regions of interest are used to search for a signal and account for the residual cosmic-ray background after γ/hadron separation. We find no excess of dark matter signals, and thus place some of the strongest γ-ray constraints on the lifetime of heavy dark matter particles with mass between 10^{5} and 10^{9}  GeV. Our results with LHAASO are robust, and have important implications for dark matter interpretations of the diffuse astrophysical high-energy neutrino emission.

[Analysis of suicide ideation and its influencing factors among nursing staff of different grades in different hospitals during their career]

Objective: To analyze the prevalence and related factors of suicide ideation among nurses in different levels of hospitals in Shandong Province, and to analyze the relationship between them. Methods: From June to July 2020, 1644 nurses in Shandong Province were surveyed by multi-stage stratified cluster sampling. The suicidal ideation of nurses was investigated by suicidal ideation screening. Social support and mental health were measured by the perceived social support scale (pass) and kessler10 scale respectively. The simple coping style scale (SCSQ) was used to evaluate the coping styles of the subjects when they encountered problems. Logistic regression was used to analyze the influencing factors of suicidal ideation, Amos software was used to establish the path model of suicidal ideation related factors, and the maximum likelihood estimation was used to test the path model coefficient. Results: The incidence of suicidal ideation among nurses in secondary hospitals during their career was 8.44%, and that in tertiary hospitals was 11.66%. There was no significant difference in suicidal ideation among nurses at all levels in secondary hospitals (P>0.05) . The main factors related to suicidal ideation were unmarried and others (OR=0.362, 95%CI=0.155, 0.844, P=0.019) , social support (OR=1.084, 95% CI=1.059, 1.109, P=0.000) and mental health status (OR=0.921, 95% CI=0.890, 0.953, P=0.000) . The suicide ideation of skilled nurses in tertiary hospitals was higher than that of other levels (P<0.05) . The related factors of suicide ideation mainly included unmarried and others (OR=0.369, 95% CI=0.214, 0.636, P=0.000) , night shift (OR=1.889, 95%CI=10.57, 3.377, P=0.032) , general self-rated social status (OR=2.377, 95%CI=1.031, 5.483, P=0.042) , physical disease (OR=2.747, 95%CI=1.601, 4.714) , P=0.000) , Social support (OR=0.960, 95%CI=1.042, 1.077, P=0.000) and mental health status (OR=0.942, 95%CI=0.922, 0.963, P=0.000) . Social support and mental health have a direct effect on suicidal ideation. Self-assessment of social status, social support and physical disease can affect suicidal ideation by affecting mental health. Conclusion: It is necessary to pay more attention to the mental health status of nurses at different levels in different hospitals during their career, improve their social support level, and improve their cognition of the practice environment.

Exploring Lorentz Invariance Violation from Ultrahigh-Energy γ Rays Observed by LHAASO

Recently, the LHAASO Collaboration published the detection of 12 ultrahigh-energy γ-ray sources above 100 TeV, with the highest energy photon reaching 1.4 PeV. The first detection of PeV γ rays from astrophysical sources may provide a very sensitive probe of the effect of the Lorentz invariance violation (LIV), which results in decay of high-energy γ rays in the superluminal scenario and hence a sharp cutoff of the energy spectrum. Two highest energy sources are studied in this work. No signature of the existence of the LIV is found in their energy spectra, and the lower limits on the LIV energy scale are derived. Our results show that the first-order LIV energy scale should be higher than about 10^{5} times the Planck scale M_{Pl} and that the second-order LIV scale is >10^{-3}M_{Pl}. Both limits improve by at least one order of magnitude the previous results.

Peta-electron volt gamma-ray emission from the Crab Nebula

The Crab Nebula is a bright source of gamma rays powered by the Crab Pulsar's rotational energy through the formation and termination of a relativistic electron-positron wind. We report the detection of gamma rays from this source with energies from 5 × 10^-4 to 1.1 peta-electron volts with a spectrum showing gradual steepening over three energy decades. The ultrahigh-energy photons imply the presence of a peta-electron volt electron accelerator (a pevatron) in the nebula, with an acceleration rate exceeding 15% of the theoretical limit. We constrain the pevatron's size between 0.025 and 0.1 parsecs and the magnetic field to ≈110 microgauss. The production rate of peta-electron volt electrons, 2.5 × 10³⁶ ergs per second, constitutes 0.5% of the pulsar spin-down luminosity, although we cannot exclude a contribution of peta-electron volt protons to the production of the highest-energy gamma rays.

Extended Very-High-Energy Gamma-Ray Emission Surrounding PSR J0622+3749 Observed by LHAASO-KM2A

We report the discovery of an extended very-high-energy (VHE) gamma-ray source around the location of the middle-aged (207.8 kyr) pulsar PSR J0622+3749 with the Large High-Altitude Air Shower Observatory (LHAASO). The source is detected with a significance of 8.2σ for E>25  TeV assuming a Gaussian template. The best-fit location is (right ascension, declination) =(95.47°±0.11°,37.92°±0.09°), and the extension is 0.40°±0.07°. The energy spectrum can be described by a power-law spectrum with an index of -2.92±0.17_{stat}±0.02_{sys}. No clear extended multiwavelength counterpart of the LHAASO source has been found from the radio to sub-TeV bands. The LHAASO observations are consistent with the scenario that VHE electrons escaped from the pulsar, diffused in the interstellar medium, and scattered the interstellar radiation field. If interpreted as the pulsar halo scenario, the diffusion coefficient, inferred for electrons with median energies of ∼160  TeV, is consistent with those obtained from the extended halos around Geminga and Monogem and much smaller than that derived from cosmic ray secondaries. The LHAASO discovery of this source thus likely enriches the class of so-called pulsar halos and confirms that high-energy particles generally diffuse very slowly in the disturbed medium around pulsars.

Ultrahigh-energy photons up to 1.4 petaelectronvolts from 12 γ-ray Galactic sources

The extension of the cosmic-ray spectrum beyond 1 petaelectronvolt (PeV; 10¹⁵ electronvolts) indicates the existence of the so-called PeVatrons-cosmic-ray factories that accelerate particles to PeV energies. We need to locate and identify such objects to find the origin of Galactic cosmic rays¹. The principal signature of both electron and proton PeVatrons is ultrahigh-energy (exceeding 100 TeV) γ radiation. Evidence of the presence of a proton PeVatron has been found in the Galactic Centre, according to the detection of a hard-spectrum radiation extending to 0.04 PeV (ref. ²). Although γ-rays with energies slightly higher than 0.1 PeV have been reported from a few objects in the Galactic plane^3-6, unbiased identification and in-depth exploration of PeVatrons requires detection of γ-rays with energies well above 0.1 PeV. Here we report the detection of more than 530 photons at energies above 100 teraelectronvolts and up to 1.4 PeV from 12 ultrahigh-energy γ-ray sources with a statistical significance greater than seven standard deviations. Despite having several potential counterparts in their proximity, including pulsar wind nebulae, supernova remnants and star-forming regions, the PeVatrons responsible for the ultrahigh-energy γ-rays have not yet been firmly localized and identified (except for the Crab Nebula), leaving open the origin of these extreme accelerators.

[Endemic situation of schistosomiasis in national surveillance sites of Zhejiang Province from 2015 to 2019]

OBJECTIVE

To analyze the endemic situation of schistosomiasis in national surveillance sites of Zhejiang Province, so as to provide the scientific evidence for formulating the new schistosomiasis surveillance program and consolidating schistosomiasis elimination achievements.

METHODS

A total of 54 to 55 national surveillance sites and 6 risk monitoring sites were assigned in historical endemic regions of Zhejiang Province from 2015 to 2019, where the Schistosoma japonicum infections in humans, livestock, snails and wild feces were monitored. All data pertaining to the surveillance results were descriptively analyzed.

RESULTS

There were 34 530 person-time local residents receiving serological screening for S. japonicum infections in national surveillance sites of Zhejiang Province from 2015 to 2019, and the seroprevalance of S. japonicum infections were 0.29% to 0.68%; however, no egg-positives were detected. During the period from 2015 to 2019, there were 62 086 person-time mobile populations receiving serological screening for S. japonicum infections in national surveillance sites of Zhejiang Province, and the seroprevalance of S. japonicum infections were 0.32% to 0.56%; additionally, there were 27 egg-positives identified, including 3 imported cases with schistosomiasis haematobia and one case with acute schistosomiasis japonica, indicating that the adjusted prevalence of Schistosoma infections were 0.01% to 0.07% among mobile populations. A total of 829 livestock were examined for S. japonicum infections, with no positives detected. There were 10.55 hm² and 2.89 hm² snail habitats found in national surveillance sites and risk monitoring sites of Zhejiang Province during the 5-year period, respectively; however, no S. japonicum infections were identified in snails. Moreover, a total of 305 wild feces were tested for S. japonicum infections, and no egg-positives were identified.

CONCLUSIONS

The schistosomiasis elimination achievement have been consolidated in Zhejiang Province; however, the risk factors of re-emerging schistosomiasis have not been completely eliminated, such as residual snails and imported schistosomiasis cases. Further surveillance and control activities of snails and the source of S. japonicum infections should be reinforced.

[Evaluation on the effect of exclusive breastfeeding among women with primipara, using the Information-motivation-behavioral skills model intervention model]

Objective: To explore the effects of intervention programs during primipara, using the Information-motivation-behavioral skills model (IMB) intervention model on initial exclusive breastfeeding. Method: 206 women of primiparas who were registered to the top three hospitals were selected in Shandong province, 2018. These women were hospitalized in the obstetrics/gynaecology wards during the later periods. IMB model was used to support the intervention programs at the following stages: antenatal period, 1 day postpartum, 3-4 days postpartum and 42 days postpartum. Questionnaire regarding self-efficacy energy meter, knowledge and behavior related to breastfeeding, were used before and after the intervention programs. Results: Through intervention programs, statistically significant differences in breastfeeding self-efficacy scores between the four stages (F=150.680, P=0.000) were recorded. Significant differences were also noticed in scores on knowledge of breastfeeding (F=176.556, P=0.000). Conclusion: The application of IMB intervention model in women at childbearing age seemed to be helpful in improving the effect of primary breastfeeding in women at childbearing age.

[Clinicopathological features and prognosis of 488 patients with neuroendocrine tumors]

Objective: To investigate the clinicopathological features and prognosis of patients with neuroendocrine tumors (NETs). Methods: The clinicopathologic data of enrolled patients with NETs between October 2012 and October 2017 at the First Affiliated Hospital of Zhengzhou University were retrospectively analyzed. Results: Among the 488 NETs patients, the average age was (51.0±15.8) years, and the sex ratio (male/female) was 1∶1.1. Of the NETs, 370 were located in the digestive system (75.8%), 63 were pulmonary (12.9%), 14 were mediastinal (2.9%), 7 were of unknown primary origin (1.4%), and 34 were located in other sites (7.0%). Among the NETs, the pancreas, rectum and stomach were the most common sites. In the digestive system NETs, the most common tumor grade was G1 (190 cases, 51.4%), followed by G2 (143 cases, 38.6%) and NET-G3 (37 cases, 10.0%). In pulmonary NETs, typical and atypical carcinoid tumors was 47.6% and 52.4%, respectively. There were 310 patients at stage Ⅰ/Ⅱ, 53 at stage Ⅲ, 69 at stage Ⅳ and 56 at stage undiagnosed, respectively. The relationships among age, stage, grade, metastasis, treatment and prognosis were analyzed. All these factors could influence the survival rate of NET patients. Multivariate Cox analysis showed that age (>50 years old) (HR=2.831, 95%CI:1.414-7.029, P=0.025) and distant metastasis (HR=10.208, 95%CI:4.110-25.355, P<0.001) were independent risk factors. Conclusions: The most common primary sites of NETs are the pancreas, rectum, and stomach. Age and distant metastasis are independent risk factors for the prognosis of NETs.

Functional and structural profiles of GST gene family from three Populus species reveal the sequence-function decoupling of orthologous genes

A common assumption in comparative genomics is that orthologous genes are functionally more similar than paralogous genes. However, the validity of this assumption needs to be assessed using robust experimental data. We conducted tissue-specific gene expression and protein function analyses of orthologous groups within the glutathione S-transferase (GST) gene family in three closely related Populus species: Populus trichocarpa, Populus euphratica and Populus yatungensis. This study identified 21 GST orthologous groups in the three Populus species. Although the sequences of the GST orthologous groups were highly conserved, the divergence in enzymatic functions was prevalent. Through site-directed mutagenesis of orthologous proteins, this study revealed that nonsynonymous substitutions at key amino acid sites played an important role in the divergence of enzymatic functions. In particular, a single amino acid mutation (Arg39→Trp39) contributed to P. euphratica PeGSTU30 possessing high enzymatic activity via increasing the hydrophobicity of the active cavity. This study provided experimental evidence showing that orthologues belonging to the gene family have functional divergences. The nonsynonymous substitutions at a few amino acid sites resulted in functional divergence of the orthologous genes. Our findings provide new insights into the evolution of orthologous genes in closely related species.

[An study on the incidence of heat stroke and explore it's prediction model in Pudong New Area of Shanghai from 2013-2017]

Objective: To know the incidence of heat stroke and explore it's prediction model in Pudong New Area of Shanghai. Methods: An epidemiological investigation was conducted on heat stroke cases in Pudong New Area of Shanghai from 2013 to 2017. Daily temperature data during this period were collected to explore it's influence. Results: 246 heat stroke cases were reported and investigated, 70.3% (173/246) of them were male. 170 cases are severe heat stroke, accounting for 69.1%. 28 patients died, accounting for 11.4% of all cases of heat stroke, and 16.5% (28/170) of severe heat stroke cases. Thermoplegia (56.5%, 96/170) was the most popular type among severe heat stroke cases. Heat prostration, heat cramps and mixed type account for 17.1% (29/170) , 12.4% (21/170) and 14.0% (24/170) respectively. Scatter plot and linear regression demonstrated that there was a significant linear relation between number of high temperature days and number of heat stroke cases (P<0.01) . And the prediction model is: Predictive number of annual heat stroke cases=β×Number of annual high temperature days+Intercept. Leave-one-out cross validation result shows that the predictive number of annual heat stroke cases from 2013 to 2017 were 85.7%, 90.9%, 83.3%, 91.9 and 84.3% respectively. Conclusion: There was a significant linear relation between number of high temperature days and number of heat stroke cases in Pudong New Area. The related work arrangement for heat stroke prevention could be well planed according to the prediction model.

Optimal parameters and location for diffusion tensor imaging in the diagnosis of carpal tunnel syndrome: a meta-analysis

AIM

To assess the diagnostic value of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of diffusion tensor imaging (DTI) at several anatomical locations in patients with carpal tunnel syndrome (CTS) to explore the optimal parameters and measurement location.

MATERIALS AND METHODS

A search was conducted using the PubMed, EBSCO, Ovid, Web of Science, and Cochrane databases to identify articles relevant to this study published before September 2017. Studies were selected and included according to strict eligibility criteria. Mean differences (MD) and 95% confidence intervals (CIs) were used to compare FA and ADC values between CTS patients and healthy subjects. Potential publication bias was investigated.

RESULTS

Eleven studies involving 349 CTS wrists and 278 controls were selected for the meta-analysis. A notable MD: was found for lowered FA at the level of the pisiform bone for CTS versus controls (MD: -0.11, 95% confidence interval [CI]: -1.14 to -0.07, z=5.83, p<0.001). A higher ADC was found at the pisiform bone and hamate bone levels for CTS versus controls (P: MD: 0.15, 95% CI: 0.10 to 0.20, z=5.98, p<0.001, H: MD: 0.15; 95% CI: 0.09 to 0.21, z=4.67, p<0.001).

CONCLUSIONS

The meta-analysis demonstrated a significant FA reduction and ADC increase in CTS patients. This result supports the use of DTI parameters in differentiating CTS patients from health subjects. The anatomical site for FA at the pisiform and ADC at the pisiform and hamate levels were more accessible than other sites for the diagnosis of CTS patients.

An instrument for measuring scintillators efficiently based on silicon photomultipliers

An instrument used for measuring multiple scintillators' light output and energy resolution was developed. The instrument consisted of a light sensor array which was composed of 64 discrete SiPMs (Silicon Photomultipliers), a corresponding individual channel readout electronics system, and a data processing algorithm. A Teflon grid and a large interval between adjacent SiPMs were employed to eliminate the optical cross talk among scintillators. The scintillators' light output was obtained by comparing with a reference sample with known light output. Given the SiPM temperature dependency and the difference among each SiPM, a temperature offset correction algorithm and a non-uniformity correction algorithm were added to the instrument. A positioning algorithm, based on nine points, was designed to evaluate the performance of a scintillator array. Tests were performed to evaluate the instrument's performance. The uniformity of 64 channels for light output measurement was better than 98%, the stability was better than 98% when temperature varied from 15 °C to 40 °C, and the nonlinearity under 511 keV was better than 2%. This instrument was capable of selecting scintillators and evaluating the packaging technology of scintillator arrays with high efficiency and accuracy.

Intercomparison of methods for coincidence summing corrections in gamma-ray spectrometry--part II (volume sources)

The second part of an intercomparison of the coincidence summing correction methods is presented. This exercise concerned three volume sources, filled with liquid radioactive solution. The same experimental spectra, decay scheme and photon emission intensities were used by all the participants. The results were expressed as coincidence summing corrective factors for several energies of (152)Eu and (134)Cs, and different source-to-detector distances. They are presented and discussed.

Hemisphere Differences in Accessing Lexical Knowledge of Chinese Characters

The lateralisation of lexical knowledge of Chinese characters is investigated in this study. Three experiments were conducted in which stimuli were presented unilaterally to a visual field for recognition tests. The orthographic similarity of two alternative items for choice in Experiment 1 was manipulated, and the results showed an LVF advantage effect for legal characters in the visually similar condition and a more prominent LVF than RVF character-superiority effect. The phonological similarity of two alternative items for choice was manipulated in Experiment 2. The results showed a prominent RVF advantage effect and a significant phonological similarity effect in the RVF. In Experiment 3, the semantic similarity was manipulated, and the semantic similarity effect was observed in the RVF. These results suggest hemisphere asymmetries in accessing lexical knowledge of Chinese characters.

Note: A sampling method for quantum random bit generation

In this note, we present a new sampling method for quantum random bit generation. The new method requires only one single-photon detector and does not measure the time slots of emitted photons. A binary random bit sequence obtained is independent on the time slot of the pulses and the precision of the measurement instrument. The effect of the exclusive-or operation for eliminating the bias in the raw sequences is also discussed.

Rapid diagnosis of tuberculosis directly from clinical specimens using a gene chip

The aim of this study was to explore a gene chip capable of detecting the presence of Mycobacterium tuberculosis isolates directly in clinical sputum specimens and to compare it with current molecular detection techniques. At first, we selected 13 M. tuberculosis-specific target genes to construct a gene chip for rapid diagnosis. Using the membrane array method, we diagnosed M. tuberculosis by gene chip directly from 246 sputum specimens from patients suspected of having tuberculosis. Among 80 M. tuberculosis complex (MTBC) culture-positive sputum specimens, the MTBC detection rate was 62.5% (50/80) by PCR-restriction fragment length polymorphism (RFLP), 70% (56/80) by acid-fast staining, and 85% (68/80) by the membrane array method. Furthermore, subspecies showed different gene expression patterns in the membrane array. In conclusion, MTBC could be detected directly in sputum by the membrane array method. The rapidity of detection and the capability of differentiating subspecies could make this method useful in the control and prevention of tuberculosis.

Expression, crystallization and preliminary X-ray studies of the recombinant PTB domain of mouse dok1 protein

The PTB domain of mouse dok1 fusion protein has been overexpressed in Escherichia coli and crystallized in a form suitable for X-ray crystallographic study. Crystals have been obtained using the vapour-diffusion method and belong to space group P2(1)2(1)2(1). X-ray diffraction data were collected in-house to 2.5 A resolution. A selenomethionine (SeMet) dok1 PTB fusion-protein derivative was expressed using the same expression system, purified in a reductive environment and crystals were obtained under similar conditions. Subsequently, three different wavelength data sets from the derivative crystal were collected to 2.5 A resolution at SPring-8.

Betel quid chewing and risk of adverse birth outcomes among aborigines in eastern Taiwan

It is known that substance abuse during pregnancy is associated with increased risk of adverse birth outcomes. The aim of this study was to determine the use of alcohol, cigarettes, betel quid, and drugs among pregnant aboriginal women and to assess the risk of adverse effects of betel quid use on birth outcomes in eastern Taiwan. Of a total of 229 women recruited into this study, 32 women with adverse birth outcomes constituted the case group. Analyses revealed that adverse birth outcomes were associated with maternal betel quid chewing and maternal age. After adjusting for maternal age, the risk of adverse birth outcome was five times higher among betel quid chewing women as compared to substance nonusers. Based on this finding, it is suggested health education, especially when concerned with the harmful effects of substance abuse, which includes betel quid use during pregnancy, should be stressed in concert with routine prenatal care.

Work experience and drinking behavior: alienation, occupational status, workplace drinking subculture and problem drinking

This study explored the association between alienating job conditions and problem drinking within the context of occupational status and workplace drinking subculture. From December 1994 to March 1995, a questionnaire survey was implemented in the manufactory sector in southern Taiwan. Within the questionnaire, any perceived self-estrangement, powerlessness and social isolation that the individual experienced in his work were measured as the alienating job conditions, and any negative physical, psychological and social consequences the individual experienced during the previous month were considered as affecting problem drinking. Of the 1117 subjects, 668 (61.8%) reported imbibing one or more drinks during the preceding month; the average daily alcohol consumption being 0.2+/-0.9 drinks. In addition, 188 (16.8%) subjects reported having experienced drinking-related problems in the preceding month. Workers with low occupational status were more likely to become problem drinkers when they felt comparatively self-estranged in their work. Further, those with a family history including any habitual drinker or those under more encouraging workplace drinking subculture were more likely to have drinking-related problems. For the prevention of problem-related drinking behavior, the workplace should be considered as the focus of our future intervention and management program.

Prevalence and correlates of substance use among clinical nurses in Kaohsiung city

Though substance abuse and its deleterious health sequelae are a serious problem in Taiwan, licit and illicit substance use patterns among nurses are understudied. The purpose of this study was to investigate the prevalence of substance use and to identify its related factors among clinical nurses. A total of 907 registered nurses were recruited for this study via stratified-random sampling from hospitals in Kaohsiung city. Each participant was requested to reply to a structured questionnaire anonymously and a 98.1% response rate was achieved. Prevalence of substance use during the past year was estimated as follows: alcohol drinking (regular use-3.8%); coffee drinking (regular use-44.7%); cigarette smoking (regular use-0.2%); regular use of analgesics 21.1%; regular use of benzodiazepines 1.8%; use of narcotics (ever use-0.7%). Significant factors related to substance use were analyzed by logistic regression. This revealed that for regular alcohol use, the significant factor was a positive attitude toward substance use; for BZD drug use, they were poor mental health, positive attitude toward substance use, being unmarried, and used analgesics; for regular analgesics use, they were work in non-critical care unit, self-perceived poor health status, and BZD drug use. Results generated from this study may act as reference for nursing administration to develop an effective health promotion program of physical and mental health for the clinical nurses.

Mid-infrared w quantum-well lasers for noncryogenic continuous-wave operation

We review the recent progress of electrically injected and optically pumped mid-IR lasers based on antimonide quantum wells with the type II W configuration. W quantum-well diodes have achieved cw operation up to 195 K at lambda = 3.25 mum. Optically pumped devices that employ the diamond pressure bond heat sink have reached 290 K at 3 mum and 210 K at 6 mum. Pulsed power conversion efficiencies of up to 7% at 220 K have been attained by use of an optical pumping injection cavity approach, in which an etalon cavity for the pump beam significantly enhances its absorptance. The angled-grating distributed-feedback configuration has been used to obtain near-diffraction-limited output for an optical pumping stripe width of 50 mum.

Predictors of readmission to a medical-psychiatric unit among patients with minor mental disorders

BACKGROUND

Most studies on readmission have focused on patients with severe mental disorders such as schizophrenia and subjects were mostly collected in traditional psychiatric settings. This study investigated the predictors of readmission to a medical-psychiatric unit among patients with minor mental disorders in a general hospital.

METHODS

All 164 patients admitted to a stress ward within a one-year period were recruited into this study. Data were retrospectively obtained by reviewing medical charts. Variables used to analyze and compare between patients who were and were not readmitted included patient characteristics, clinical features and multiple axes diagnoses of DSM-IV.

RESULTS

Of 164 patients recruited, 135 were hospitalized only one time. The remaining 29 patients accounted for 61 admissions. The readmission rate was 17.7% (29/164). The significant predictors for readmission included Global Assessment of Functioning scores lower than 50 at admission, age under 40 years, previous psychiatric admission, alcohol dependence/abuse, dysthymia and comorbidity of borderline personality disorder. Using logistic regression to predict readmission within one year, we found the first four variables accurately differentiated 84.15% of patients who were readmitted from those who were not.

CONCLUSIONS

Our results indicated the incidence of relapse in certain minor mental disorders is similar to that of severe mental disorders. By identifying predictors of readmission and intervening appropriately, unnecessary readmission may be prevented.

Mental health in Asia: social improvements and challenges

Remarkable improvements in economic conditions and a considerable upgrade in the quality of life have been observed in many parts of Asia during the past several decades. At the same time, many mental health challenges face the people of Asia. Various social mental health indexes are reviewed here, with available data from China, Japan, Korea, Singapore, Malaysia, and other Asian societies. The data are compared with data from the United States, Australia in the Pacific Rim, and some other Western countries to examine patterns of similarity or difference between East and West in the process of modernization. Common trends in mental health issues associated with rapid sociocultural change observed in different Asian societies are discussed, as well as the relative shortage of mental health personnel available in many Asian societies. It is emphasized that, in addition to expanding psychiatric services, there is an even more urgent need to promote mental health knowledge and concern through education in the general population. Mental health needs to be cultivated and maintained by social forces and cultural strengths. It is stressed that there is a challenge for Asian people to advance mental health beyond economic development in the 21st century.

Neighborhood experience and mental health

BACKGROUND

The purpose of this study was to evaluate individual mental health in the context of their social environment. Specifically, variables across different levels, including a person's attributes, neighborhood experience, and community characteristics, were examined to explore their relationship with that person's mental health.

METHODS

Communities in southern Taiwan, including 1 district from Kaohsiung City and 4 townships (hsiang) from Kaohsiung County, were purposively selected to represent 3 different types (urban, suburban, and rural) of communities, after which, by random sampling, 416 subjects were recruited for the interview survey in 1998. A questionnaire containing a measure for mental health (CHQ) and perceptions of neighborhood experience was administered for data collection. At the same time, data derived from governmental archives were collected to indicate the characteristics of a community, and these included population density, community socioeconomic condition, and community stability.

RESULTS

Multivariate analysis showed that personal income, community socioeconomic condition, and perceived social support from the neighborhood were statistically significant when associated with a person's mental health status. It seems that influence of an individual's mental health status was affected not only by that person's attributes, but also by the neighborhood within which he/she experiences daily life.

CONCLUSION

With respect to the strategy for implementing future mental health promotion programs, a further clarification of the relationship between social conditions and mental health is needed.

Review of pre-eclampsia in Taiwan: a multi-institutional study

BACKGROUND

Because the reported frequency of pre-eclampsia in Taiwan varies significantly, the aims of this study were to measure the current incidence of pre-eclampsia and its correlated morbidity and mortality for both mothers and fetuses in Taiwan.

METHODS

We retrospectively studied all reported cases of pre-eclampsia and eclampsia from January 1, 1993 to December 31, 1997 in the 14 tertiary medical centers and regional hospitals in Taiwan. Recruiting criteria were pregnancy-induced hypertension (systolic blood pressure > or = 140 mmHg or diastolic blood pressure > or = 90 mmHg) with proteinuria (> or = 300 mg of urinary protein per 24 hours) and independent part edema.

RESULTS

There were 4,193 patients with pre-eclampsia and eclampsia for a frequency of 2.03% of 206,551 deliveries during the study period. Of these, 58.9% of patients were classified as having mild pre-eclampsia while 38.4% had severe pre-eclampsia. Advanced maternal age (> 35 years) (odds ratio [OR] = 4.56; 95% confidence interval [CI] = 4.23-4.90; p < 0.001), primiparity (OR = 1.71; 95% CI = 1.61-1.82; p = 0.02) and twin pregnancy (OR = 1.92; 95% CI = 1.64-2.25; p = 0.01) were significant risk factors for developing pre-eclampsia. However, multivariate analysis showed that only advanced maternal age was a significant risk factor for pre-eclampsia (OR = 3.21; 95% CI = 2.95-3.50; p < 0.001). In contrast to mild pre-eclampsia, severe pre-eclampsia resulted in significantly worse outcomes for both mothers and fetuses. Complications in patients with severe pre-eclampsia included placental abruption, acute renal failure, pulmonary edema, postpartum hemorrhage, pleural effusion, preterm labor, intrauterine growth retardation, stillbirth, neonatal mortality and low birth weight infants, all of which occurred significantly more frequently than in patients with mild pre-eclampsia (p < 0.001).

CONCLUSIONS

Pre-eclampsia remains a big challenge in modern obstetrics in Taiwan. Early diagnosis and management of patients with pre-eclampsia to prevent progression would significantly improve outcomes for mothers and fetuses.

Development of the Taiwanese Depression Questionnaire

BACKGROUND

Previous studies have shown that different cultures have various modes for emotional expression which suggest that Western scales have certain limitations. The purpose of this study was to develop a culturally relevant depression screening questionnaire: the "Taiwanese Depression Questionnaire" (TDQ) which can be used to conduct epidemiological surveys in Taiwanse society.

METHODS

Based on the results of previous studies and related references, a draft of the TDQ was constructed. After several research group discussions, the first version of a 20-item draft was developed. By purposive sampling, 48 patients, from depressive disorder and anxiety disorder groups of Chang Gung Memorial Hospital's psychiatric clinics, self-rated the draft to test the wording, sequences, and its concurrent validity. After item analysis, a meeting of experts, and draft modification, an 18-item second version of the draft was established. Afterwards, 107 community subjects, recruited from Jenwu Township of Kaohsiung County, were sampled for the receiver operating characteristic (ROC) curve analysis, conventional validity index, and internal consistency of reliability.

RESULTS

The results demonstrate that Cronbach's alpha coefficient (0.90), concurrent validity, and the area under the ROC curves (0.92) are all quite satisfactory. The 18-item TDQ had a sensitivity of 0.89 and a specificity of 0.92 at a cutoff score of 19.

CONCLUSIONS

The TDQ is a culturally relevant questionnaire, which is adaptable for screening depressive people in the local communities.

[Modulation of nerve growth factor on wound healing of burn]

OBJECTIVE

To investigate the effect of nerve growth factor(NGF) on the burn wound healing and to study the mechanism of burn wound healing.

METHODS

Six domestic pigs weighting around 20 kg were used as experimental animals. Twenty-four burn wound, each 2.5 cm in diameter, were induced on every pigs by scalding. Three different concentrations of NGF, 1 microgram/ml, 2.5 micrograms/ml, 5 micrograms/ml were topically applied after thermal injury, and saline solution used as control group. Biopsy specimens were taken at 3, 5 and 9 days following treatment and immunohistochemistry method was used to detect the epidermal growth factor(EGF), EGF receptor (EGF-R), NGF, NGF receptor (NGF-R), NGF, NGF-R, CD68 and CD3.

RESULTS

The expression of EGF, EGF-R, NGF, NGF-R CD68 and CD3 were observed in the experimental group, especially at 5 and 9 days, no expression of those six items in the control group.

CONCLUSION

NGF can not only act directly on burn wound, but also modulate other growth factors on the burn wound to accelerate the healing of burn wound.

Correlated risk factors for suicidal ideation in aboriginal Southern Taiwanese women of childbearing age

Suicide and non-accidental poisoning are two important causes of death of female aborigines in Taiwan. The purpose of this study was to estimate the prevalence of suicidal ideation and then to identify factors relating to this for female aborigines of childbearing age. Using stratified random sampling 212 female aborigines, aged between 20 and 49, were recruited into this study. Participants were interviewed at their homes by trained interviewers who used a structured questionnaire. The Suicidal Ideation Screening Questionnaire (SIS-Q) was used to help predict which participants would be more likely to have suicidal ideation. The prevalence rate of suicidal ideation within the previous 12 months was 20.3% (95% CI 14.9-25.7%). Significant related factors of suicidal ideation, which were analyzed by multiple logistic regression, revealed that women suffering depressive mood, living within a extended family, and perceiving poor health status were more likely to have suicidal ideation. Results generated from this study may be used, in primary care, for guidance as to how to prevent suicide. Outreach community programs incorporating a valid and sensitive screening instrument, such as the SIS-Q, should be implemented to help prevent suicides in aboriginal communities.

Posterior uterine wall rupture during labour

Vaginal births after Caesarean section (VBAC) are well-accepted procedures when pregnant women do not have any contra-indications. The possibilities of the uterine dehisence and rupture during VBAC should always be considered. This occurrence is usually related to the previous scar tissue and subsequent risk is acceptable. Nevertheless, rupture that occurs in presumably normal tissue areas of the uterus instead of in scar tissue areas with resultant perinatal death is extremely rare. We present a 31 year old woman who had posterior uterine rupture when she tried VBAC at 38 weeks gestation. During the course of VBAC, she had a smooth labour course without use of any augmentation medication, but her condition was complicated with uterine rupture without any premonitory signal. It resulted in maternal shock and sequentially the death of the newborn 7 days after delivery. By reviewing this case report, we should keep in mind that prompt response to every woman during labour is of paramount importance to avoid repeating the occurrence of uterine rupture, partly because uterine rupture could occur without prominent signals and partly because subsequent dangers seem to be those created by acts of omission. Finally, the benefits and safety of VBAC have not been undermined because this patient is an isolated and extremely rare case.

Treatment refusal: analysis of 15 cases

BACKGROUND

In this paper, we investigate the reasons for treatment refusal at Linkou and Kaohsiung Chang Gung Memorial Hospitals, and offer ways to improve the doctor-patient relationship.

METHODS

Cases were collected during a 2-year period according to the criterion of notification of "refused treatment" on consultation sheets, with a total of 1631 consultation sheets. All cases were discussed once a week in detail by psychiatrists and the consulting medical staff, and were followed up from 1 to 4 weeks. All cases were treated by the processes of informed consent and crisis intervention. The final results for the reasons of treatment refusal and psychiatric diagnoses were made by psychiatrists and the consulting medical staff.

RESULTS

The number of cases compatible with the criterion was 15 (10 men and 5 women). The reasons for treatment refusal included poor communication, inadequate information, lack of competency, denial and shock reaction, reappearance of the suffered experience, and autonomy of patients. The distribution of psychiatric diagnoses included 8 with major depressive disorders, 2 with delirium, 1 with schizophrenic disorder, 1 with adjustment disorder, 1 with acute stress disorder (post-traffic accident), 1 with alcohol dependence, and 1 was deferred. After adequate processes of informed consent and crisis intervention, 12 persons accepted medical treatment.

CONCLUSION

We should give patients adequate informed consent and crisis intervention to establish a good doctor-patient relationship and to respect the patients' autonomy for their choice of treatment.

Biphasic changes in autonomic nervous activity during pregnancy

To understand the sequential response of the autonomic nervous system to pregnancy, we studied heart rate variability in 23 first trimester, 23 second trimester and 21 third trimester pregnant women. Twenty non-pregnant women were recruited as controls. Time and frequency domain measures of heart rate variability in three recumbent positions were compared. We found that normalized high-frequency power in the supine position increased significantly in the first trimester (42.2 (95% confidence interval (CI) 5.4) nu (normalized unit); P < 0.05) compared with non-pregnant controls (33.0 (6.0) nu), and then decreased progressively in the second (27.3 (6.7) nu) and third (21.8 (6.0) nu; P < 0.05) trimesters. The low-/high-frequency power ratio in the supine position decreased significantly in the first trimester (0.8 (0.3); P < 0.05) compared with that of non-pregnant controls (1.1 (0.3)) and increased progressively in the second (1.5 (0.4)) and third (2.1 (0.8); P < 0.05) trimesters. When the position was changed from the supine to the right lateral decubitus, the percentage change in normalized high-frequency power correlated significantly and negatively with normalized high-frequency power in the supine position in non-pregnant controls (r = -0.56, P = 0.01) and in pregnant women in the first (r = -0.44, P = 0.034), second (r = -0.68, P < 0.001) and third (r = -0.68, P < 0.001) trimesters. These results indicate that autonomic nervous activity shifted towards a lower sympathetic and higher vagal modulation in the first trimester, and changed towards a higher sympathetic and lower vagal modulation in the third trimester as gestational age increased. The balance between the haemodynamic changes of pregnancy and aortocaval compression caused by the enlarging gravid uterus may be responsible for the biphasic changes in autonomic nervous activity during pregnancy.

Return of autonomic nervous activity after delivery: role of aortocaval compression

We have compared measures of heart rate variability (HRV) in 15 women in late pregnancy before and 3 months after delivery and in 20 non-pregnant controls, to study the effect of aortocaval compression on autonomic nervous activity. Normalized high-frequency power was used as an index of vagal activity and the low-/high-frequency power ratio as index of sympathovagal balance. We found that the decrease in vagal activity and increase in sympathovagal balance before delivery returned to normal 3 months after delivery. Percentage changes in vagal activity and sympathovagal balance 3 months after delivery in the left lateral decubitus position were least among three recumbent positions. The relief of aortocaval compression as a result of delivery of the fetus may be the main cause of return of autonomic nervous activity 3 months after delivery. Postpartum hormonal changes may also contribute to return of autonomic nervous activity after delivery.

Comparison of supine and upright positions on autonomic nervous activity in late pregnancy: the role of aortocaval compression

In order to understand the effect of aortocaval compression on autonomic nervous activity, we compared the effects of supine and upright postures on measures of heart rate variability in late pregnancy. Thirty-two women in late pregnancy and 23 nonpregnant age-matched women were studied. Both time and frequency domain heart rate variability measures were compared between the supine and upright positions, and between pregnant women and controls. The pregnant women had smaller mean RR interval, standard deviation of RR intervals and normalised high-frequency power, and a larger low- to high-frequency power ratio than nonpregnant women in the supine position. When the position was changed from upright to supine in nonpregnant women, the percentage change in the mean RR interval and normalised high-frequency power were increased, whereas the percentage change in the coefficient of variation of RR interval and low- to high-frequency power ratio were decreased. In contrast, the percentage change in normalised high-frequency power was decreased and the percentage change in low- to high-frequency power ratio was increased in pregnant women when the position was changed from upright to supine. These results indicate that the vagal enhancing effect seen in normal subjects when changing position from upright to supine was reversed in women in late pregnancy. Aortocaval compression in the supine position in pregnant women might be responsible for this reversal in the autonomic response to lying down.

Color Doppler waveforms of maternal cervical internal carotid arteries in normotensive and preeclamptic gravidas

The objective of this study was to investigate and determine fitted percentiles of blood flow resistance of cervical internal carotid arteries in normal pregnancies from gestational weeks 20 to 42 and to compare the resistance indices and mean velocities of the these arteries in normotensive and preeclamptic gravidas. A duplex color apparatus with pulsed Doppler ultrasound scanner (7.5 MHz) was used to determine the resistance index and mean velocity values of maternal cervical internal carotid arteries in 310 healthy singleton gravidas (group 1) and 74 singleton preeclamptic gravidas (group 2). The resistance index and mean velocity values of the maternal cervical internal carotid arteries decrease as the gestational age increases in normal gravidas, whereas in preeclamptic pregnancies these values are no different from those in normal gravidas during the second half of the gestational period.

Color Doppler ultrasound velocimetry of internal carotid arteries in normal pregnancies

BACKGROUND

There are few reports on maternal cerebral circulation during pregnancy. Using the hypothesis that cerebral blood flow resistance decreases progressively with advancing gestational age (GA) as a consequence of estrogenic effects on the vascular system during pregnancy, we calculated the pulsatility index (PI) and the mean velocity (MV) of the maternal right internal carotid artery (ICA) in order to build fitted reference centiles.

METHODS

A total of 315 pregnant women with a single fetus were studied at 20-42 weeks' gestation. The patients had uncomplicated singleton pregnancies and were without any known fetal or maternal risk factors. Duplex color ultrasound with a pulsed Doppler scanner (7.5 MHz) was used to determine the PI and MV of the maternal ICA.

RESULTS

Among the 315 healthy pregnant women, the PI of maternal ICA decreased progressively with advancing GA, PI50th = Exp (0.3124-0.0084 x GA), (p = 0.0003), during the second half of pregnancy. The predicted 50th percentile PI values of the ICA decreased from 1.117 (5th% = 0.755, 95th% = 1.654) at 24 weeks' gestation to 0.917 (5th% = 0.659, 95th% = 1.448) at 40 weeks' gestation. The MV of the maternal ICA also decreased progressively with advancing GA, MV50th = Exp (3.855-0.0093 x GA), (p = 0.0005), during the second half of pregnancy. The predicted 50th percentile MV values in the ICA decreased from 37.811 cm/sec (5th% = 24.177 cm/sec, 95th% = 59.138 cm/sec) at 24 weeks' gestation to 32.591 cm/sec (5th% = 20.818 cm/sec, 95th% = 51.021 cm/sec) at 40 weeks' gestation.

CONCLUSIONS

Both the PI and MV of the maternal ICA decreased with GA during the second half of normal pregnancy as a result of intracerebral vessel dilatation.

Reversibility of reversible Chinese words

Reversible Chinese words are words which can be read either from left to right or vice versa. The reversibility of reversible two-character Chinese words for 101 women and 73 men, native speakers of Chinese, was estimated.

Prevalence and related risk factors of licit and illicit substances use by adolescent students in southern Taiwan

Deleterious health sequelae caused by licit and illicit substance use is a serious problem in our society. Adolescent students and particularly those who are prone to substance use are of special concern in the prevention of drug abuse. The purpose of this study was to investigate the prevalence of alcohol consumption, tobacco smoking and illicit drug use and to identify the risk factors related to these habits among adolescent students. A total of 1358 adolescent students aged 16-18 y old were recruited into this study via stratified random sampling from a vocational school in Kaohsiung city. Students were asked to complete a structured questionnaire anonymously and a 96.7% response rate was achieved. Prevalence of substances use was estimated as follows: alcohol drinking, 70.7% (boys 75.1%, girls 51.4%); tobacco smoking, 56% (boys 61.8%, girls 30.2%); illicit drug use 6.4% (boys 6.6%, girls 5.6%). Significant risk factors that emerged as common correlates with substances use were behaviour problems, non-negative attitude toward parent's substance use, and peer influence. A dose-response relationship was found between the prevalence of drinking, smoking, illicit drug use and the number of risk factors adolescents were exposed to. Prevention of adolescent substance abuse should be attempted and risk factors should be reduced. An educational approach is essential not only to gain/impart knowledge of substance abuse, but also to develop an effective program for health and social development.

The effect of position on autonomic nervous activity in late pregnancy

We investigated the effect of three different recumbent positions on autonomic nervous activity in late pregnancy. Thirty pregnant and 24 nonpregnant aged-matched women were studied, and measures of heart rate variability in both time and frequency domains were compared using supine, right and left lateral decubitus positions. In the nonpregnant women, the normalised high-frequency power was greatest in the right lateral decubitus position. In the pregnant women, the normalised high-frequency power was lowest and the low/high-frequency power ratio was greatest in the supine position. Both the percentage decrease of normalised high-frequency power and the percentage increase of low/high-frequency power ratio in the supine and right lateral positions were greater than those in the left lateral position. For women in late pregnancy, the left lateral decubitus position may be beneficial because cardiac vagal activity is least suppressed and cardiac sympathetic activity is least enhanced. Aortocaval compression might be the mechanism underlying the change in cardiac autonomic nervous activity when supine and right lateral decubitus positions are assumed in late pregnancy.