132 research outputs found
Roadside LiDAR Assisted Cooperative Localization for Connected Autonomous Vehicles
Advancements in LiDAR technology have led to more cost-effective production
while simultaneously improving precision and resolution. As a result, LiDAR has
become integral to vehicle localization, achieving centimeter-level accuracy
through techniques like Normal Distributions Transform (NDT) and other advanced
3D registration algorithms. Nonetheless, these approaches are reliant on
high-definition 3D point cloud maps, the creation of which involves significant
expenditure. When such maps are unavailable or lack sufficient features for 3D
registration algorithms, localization accuracy diminishes, posing a risk to
road safety. To address this, we proposed to use LiDAR-equipped roadside unit
and Vehicle-to-Infrastructure (V2I) communication to accurately estimate the
connected autonomous vehicle's position and help the vehicle when its
self-localization is not accurate enough. Our simulation results indicate that
this method outperforms traditional NDT scan matching-based approaches in terms
of localization accuracy.Comment: Accepted by 2023 International Conference on Intelligent Computing
and its Emerging Application
Flowsim: A Modular Simulation Platform for Microscopic Behavior Analysis of City-Scale Connected Autonomous Vehicles
As connected autonomous vehicles (CAVs) become increasingly prevalent, there
is a growing need for simulation platforms that can accurately evaluate CAV
behavior in large-scale environments. In this paper, we propose Flowsim, a
novel simulator specifically designed to meet these requirements. Flowsim
offers a modular and extensible architecture that enables the analysis of CAV
behaviors in large-scale scenarios. It provides researchers with a customizable
platform for studying CAV interactions, evaluating communication and networking
protocols, assessing cybersecurity vulnerabilities, optimizing traffic
management strategies, and developing and evaluating policies for CAV
deployment. Flowsim is implemented in pure Python in approximately 1,500 lines
of code, making it highly readable, understandable, and easily modifiable. We
verified the functionality and performance of Flowsim via a series of
experiments based on realistic traffic scenarios. The results show the
effectiveness of Flowsim in providing a flexible and powerful simulation
environment for evaluating CAV behavior and data flow. Flowsim is a valuable
tool for researchers, policymakers, and industry professionals who are involved
in the development, evaluation, and deployment of CAVs. The code of Flowsim is
publicly available on GitHub under the MIT license
Ghrelin stimulates neurogenesis in the dorsal motor nucleus of the vagus
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65942/1/jphysiol.2004.064121.pd
Efficient producer mobility support in named data networking
Named Data Networking (NDN) is a promising architecture for the future Internet and it is mainly designed for efficient content delivery and retrieval. However, producer mobility support is one of the challenging problems of NDN. This paper proposes a scheme which aims to optimize the tunneling-based producer mobility solution in NDN. It does not require NDN routers to change their routing tables (Forwarding Information Base) after a producer moves. Instead, the Interest packet can be sent from a consumer to the moved producer using the tunnel. The piggybacked Data packet which is sent back to the consumer will trigger the consumer to send the following Interest packets through the optimized path to the producer. Moreover, a naming scheme is proposed so that the NDN caching function can be fully utilized. An analysis is carried out to evaluate the performance of the proposal. The results indicate that the proposed scheme reduces the network cost compared to related works and supports route optimization for enhanced producer mobility support in NDN
Implantable Cardioverter-Defibrillator Implantation in a Patient with Atrial Standstill
We report a 55-year-old female patient who presented with no P waves but with a wide QRS complex escape rhythm at 44 beats/min and prolonged QTc of 0.55 seconds on ECG. The patient had recurrence of ventricular fibrillations and loss of consciousness, and underwent defibrillation and cardiopulmonary resuscitation (CPR) several times because of cardiac arrest. The transthoracic echocardiography showed dilated cardiomyopathy and enlargement of both atria. The Doppler echocardiography documented the absence of A wave in the tricuspid and mitral valve flow. An electrophysiologic study demonstrated electrical inactivity in the right and left atria. Atrial pacing with maximum output did not capture the atria. These findings together with her electrocardiographic finding indicated atrial standstill. Sudden cardiac death was her first clinical manifestation of ventricular arrhythmia. The patient remained asymptomatic after receiving a single chamber implantable cardioverter-defibrillator (ICD) with VVI pacemaker function
Peptide YY, Cholecystokinin, Insulin and Ghrelin Response to Meal did not Change, but Mean Serum Levels of Insulin is Reduced in Children with Prader-Willi Syndrome
Prader-Willi syndrome (PWS) is a contiguous gene syndrome characterized by uncontrollable eating or hyperphagia. Several studies have confirmed that plasma ghrelin levels are markedly elevated in PWS adults and children. The study of anorexigenic hormones is of interest because of their regulation of appetite by negative signals. To study the pattern and response of the anorexigenic hormones such as cholecystokinin (CCK) and peptide YY (PYY) to a meal in PWS, we measured the plasma CCK, PYY, ghrelin and serum insulin levels in PWS patients (n=4) and in controls (n=4) hourly for a day, and analyzed hormone levels and hormonal responses to meals. Repeated measures of ANOVA of hormone levels demonstrated that only insulin levels decreased (p=0.013) and CCK (p=0.005) and ghrelin (p=0.0007) increased in PWS over 24 hr. However, no significant group x time interactions (ghrelin: p=0.89, CCK: p=0.93, PYY: p=0.68 and insulin: p=0.85) were observed; in addition, there were no differences in an assessment of a three-hour area under the curve after breakfast. These results suggest that the response pattern of hormones to meals in PWS patients parallels that of normal controls. In addition, the decrease of insulin levels over 24 hr, in spite of obesity and elevated ghrelin levels, suggests that the baseline insulin level, not the insulin response to meals, may be abnormal in patients with PWS
Marked Suppression of Ghrelin Concentration by Insulin in Prader-Willi Syndrome
The plasma ghrelin has been reported to be elevated in Prader-Willi syndrome (PWS) and modulated by insulin. It was hypothesized that insulin might have a more pronounced effect on reducing plasma ghrelin in PWS patients, which would influence appetite. This study investigated the degree of ghrelin suppression using an euglycemic hyperinsulinemic clamp in children with PWS (n=6) and normal children (n=6). After a 90-min infusion of insulin, the plasma ghrelin level decreased from a basal value of 0.86Β±0.15 to 0.58Β±0.12 ng/mL in the controls, and from 2.38Β±0.76 to 1.12Β±0.29 ng/mL in children with PWS (p=0.011). The area under the curve below the baseline level over the 90 min insulin infusion was larger in children with PWS than in controls (-92.82Β±44.4 vs. -10.41Β±2.87 ng/mL/90 min) (p=0.011). The insulin sensitivity measured as the glucose infusion rate at steady state was similar in the two groups (p=0.088). The decrease in the ghrelin levels in response to insulin was more pronounced in the children with PWS than in the controls. However, the level of ghrelin was always higher in the children with PWS during the clamp study. This suggests that even though insulin sensitivity to ghrelin is well maintained, an increase in the baseline ghrelin levels is characteristic of PWS
GSTT2 promoter polymorphisms and colorectal cancer risk
BACKGROUND: Glutathione S-transferases are a group of enzymes that participate in detoxification and defense mechanisms against toxic carcinogens and other compounds. These enzymes play an important role in human carcinogenesis. In the present study, we sought to determine whether GSTT2 promoter single nucleotide polymorphisms (SNPs) are associated with colorectal cancer risk. METHODS: A total of 436 colorectal cancer patients and 568 healthy controls were genotyped for three GSTT2 promoter SNPs (-537G>A, -277T>C and -158G>A), using real-time TaqMan assay and direct sequencing. An electrophoretic mobility shift assay (EMSA) was performed to determine the effects of polymorphisms on protein binding to the GSTT2 promoter. RESULTS: The -537A allele (-537G/A or A/A) was significantly associated with colorectal cancer risk (OR = 1.373, p = 0.025), while the -158A allele (-158G/A or A/A) was involved in protection against colorectal cancer (OR = 0.539, p = 0.032). Haplotype 2 (-537A, -277T, -158G) was significantly associated with colorectal cancer risk (OR = 1.386, p = 0.021), while haplotype 4 (-537G, -277C, -158A) protected against colorectal cancer (OR = 0.539, p = 0.032). EMSA data revealed lower promoter binding activity in the -537A allele than its -537G counterpart. CONCLUSION: Our results collectively suggest that SNPs and haplotypes of the GSTT2 promoter region are associated with colorectal cancer risk in the Korean population
Body Weight and Plasma Levels of Ghrelin and Leptin during Treatment with Olanzapine
Although enhanced appetite and weight gain are potential side effects of treatment with antipsychotic agents, particularly olanzapine and clozapine, the mechanisms underlying these side effects are poorly understood. Leptin and ghrelin were recently identified as hormones that play crucial roles in the regulation of energy balance and glucose metabolism. To elucidate relationships between weight change and plasma levels of ghrelin and leptin, we investigated the circulating ghrelin and leptin levels and body weight during olanzapine treatment. Twenty-four patients with schizophrenia were examined during 6-month administration of olanzapine. Ghrelin, leptin, weight and body mass index (BMI) were measured before and after 2, 4, 8, 12, 16, and 24 weeks of olanzapine treatment. The concentration of glucose and various lipid metabolic parameters were measured at baseline and at 24 weeks. Significant increases in weight, BMI and leptin were observed at week 24. On the other hand, the serum levels of ghrelin decreased significantly after olanzapine treatment. In addition, the level of ghrelin was negatively correlated with the leptin level, BMI and weight. The leptin level was positively correlated with both BMI and weight. Ghrelin is associated with metabolic changes, in combination with leptin, during olanzapine treatment. However, further large-scale and longitudinal studies are warranted to elucidate the metabolic changes involving ghrelin, leptin and insulin during treatment with antipsychotics
Ξ²-Elemene Piperazine Derivatives Induce Apoptosis in Human Leukemia Cells through Downregulation of c-FLIP and Generation of ROS
Ξ²-Elemene is an active component of the herb medicine Curcuma Wenyujin with reported antitumor activity. To improve its antitumor ability, five novel piperazine derivatives of Ξ²-elemene, 13-(3-methyl-1-piperazinyl)-Ξ²-elemene (DX1), 13-(cis-3,5-dimethyl-1-piperazinyl)-Ξ²-elemene (DX2), 13-(4-ethyl-1-piperazinyl)-Ξ²-elemene (DX3), 13-(4-isopropyl-1-piperazinyl)-Ξ²-elemene (DX4) and 13-piperazinyl-Ξ²-elemene (DX5), were synthesized. The antiproliferative and apoptotic effects of these derivatives were determined in human leukemia HL-60, NB4, K562 and HP100-1 cells. DX1, DX2 and DX5, which contain a secondary amino moiety, were more active in inhibiting cell growth and in inducing apoptosis than DX3 and DX4. The apoptosis induction ability of DX1 was associated with the generation of hydrogen peroxide (H2O2), a decrease of mitochondrial membrane potential (MMP), and the activation of caspase-8. Pretreatment with the antioxidants N-acetylcysteine and catalase completely blocked DX1-induced H2O2 production, but only partially its activation of caspase-8 and induction of apoptosis. HL-60 cells were more sensitive than its H2O2-resistant subclone HP100-1 cells to DX1-induced apoptosis. The activation of caspase-8 by these compounds was correlated with the decrease in the levels of cellular FLICE-inhibitory protein (c-FLIP). The proteasome inhibitor MG-132 augmented the decrease in c-FLIP levels and apoptosis induced by these derivatives. FADD- and caspase-8-deficient Jurkat subclones have a decreased response to DX1-induced apoptosis. Our data indicate that these novel Ξ²-elemene piperazine derivatives induce apoptosis through the decrease in c-FLIP levels and the production of H2O2 which leads to activation of both death receptor- and mitochondrial-mediated apoptotic pathways
- β¦