A metric to quantify the time-varying characteristics of underwater acoustic communication channels.

Underwater acoustic communication signals suffer from time dispersion due to time-varying multipath propagation in the ocean. This leads to intersymbol interference, which in turn degrades the performance of the communication system. Typically, the channel correlation functions are employed to describe these characteristics. In this paper, a metric called the channel average correlation coefficient (CACC) is proposed from the correlation function to quantify the time-varying characteristics. It has a theoretical negative relationship with communication performance. Comparative analysis involving simulations and experimental data processing highlights the superior effectiveness of CACC over the traditional metric, the channel coherence time.

Comparison between MRI-negative and positive results and the predictors for a poor prognosis in patients with idiopathic acute transverse myelitis.

BACKGROUND: Idiopathic acute transverse myelitis (IATM) is a focal inflammatory disorder of the spinal cord that results in motor, sensory, and autonomic dysfunction. However, the comparative analysis of MRI-negative and MRI-positive in IATM patients were rarely reported. OBJECTIVES: The purpose of this study was to compare MRI-negative with MRI-positive groups in IATM patients, analyze the predictors for a poor prognosis, thus explore the relationship between MRI-negative and prognosis. METHODS: We selected 132 patients with first-attack IATM at the First Affiliated Hospital of Nanchang University from May 2018 to May 2022. Patients were divided into MRI-positive and MRI-negative group according to whether there were responsible spinal MRI lesions, and good prognosis and poor prognosis based on whether the EDSS score ≥ 4 at follow-up. The predictive factors of poor prognosis in IATM patients was analyzed by logistic regression models. RESULTS: Of the 132 patients, 107 first-attack patients who fulfilled the criteria for IATM were included in the study. We showed that 43 (40%) patients had a negative spinal cord MRI, while 27 (25%) patients were identified as having a poor prognosis (EDSS score at follow-up ≥ 4). Compared with MRI-negative patients, the MRI-positive group was more likely to have back/neck pain, spinal cord shock and poor prognosis, and the EDSS score at follow-up was higher. We also identified three risk factors for a poor outcome: absence of second-line therapies, high EDSS score at nadir and a positive MRI result. CONCLUSIONS: Compared with MRI-negative group, MRI-positive patients were more likely to have back/neck pain, spinal cord shock and poor prognosis, with a higher EDSS score at follow-up. The absence of second-line therapies, high EDSS score at nadir, and a positive MRI were risk factors for poor outcomes in patients with first-attack IATM. MRI-negative patients may have better prognosis, an active second-line immunotherapy for IATM patients may improve clinical outcome.

The Impact of Ultrasound-Guided Combined with Water and Air Mixed Injection Method for Nasal Intestinal Tube Placement on Gastrointestinal Burden in Patients with Severe Acute Pancreatitis.

Objective: This study aims to investigate the impact of ultrasound-guided combined with water and air mixed injection method for nasal intestinal tube placement on gastrointestinal burden in patients with severe acute pancreatitis. Methods: A cohort of 116 patients with severe acute pancreatitis admitted to the hospital from August 2021 to July 2023 were included. They were randomly divided into the control group (58 cases, nasal intestinal tube placement using ultrasound-guided combined water injection) and the observation group (58 cases, nasal intestinal tube placement using ultrasound-guided combined with water and air mixed injection). The incubation time, volume of water injected during the incubation, nasal intestinal tube visualization rate, and success rate of one-time incubation were recorded for both groups. Gastrointestinal mucosal barrier function, Nutritional index level including intestinal fatty acid-binding protein (I-FABP), D-lactate and nutritional index levels including hemoglobin (Hb), serum albumin (ALB), retinol-binding protein (RBP) were compared between the two groups before tube placement and at 7 days after incubation. Complications in both groups were also recorded. Results: The incubation time in the observation group was shorter, and the volume of water injected during the incubation was lower than in the control group. The nasal intestinal tube visualization rate and success rate of one-time incubation were higher in the observation group (P < .05). At 7 days after incubation, the levels of I-FABP and D-lactate were lower in the observation group than in the control group (P < .05). At 7 days after incubation, The levels of I-FABP and D-lactate in the observation group were lower than those in the control group, Hb and RBP levels were higher in the observation group than in the control group (P < .05), while there was no significant difference in ALB levels between the two groups (P > .05). The incidence of complications was lower in the observation group than in the control group (P < .05). Conclusion: Ultrasound-guided combined with water and air mixed injection method for nasal intestinal tube placement in patients with severe acute pancreatitis can shorten the incubation time, reduce the volume of water injected during the incubation, improve the nasal intestinal tube visualization rate and success rate of one-time incubation, enhance gastrointestinal mucosal barrier function and nutritional index in patients, and reduce the incidence of complications.

Traceless encryption approach for physical layer security in coherent optical communications system.

We proposed and numerically studied a traceless encryption approach for physical layer security in coherent optical communications system, the most attractive advantage of which is that it is hard for eavesdroppers to be aware that the transmission signal has been encrypted because the modulation formats of encrypted signal are still the regular ones, i.e. traceless encryption. In the proposed approach, the phase only or the combination of phase and amplitude dimensions can be used for encryption and decryption. Three simple encryption rules are designed and used to investigate the encryption security performance of the scheme, in which the QPSK signal can be encrypted to be as 8PSK, QPSK and 8QAM. The results show that three simple encryption rules can cause 37.5%, 25%, 62.5% of user signal binary codes to be misinterpreted by the eavesdroppers, respectively. When the modulation formats of encrypted signal and user signal are identical, the scheme can not only cover up the real information, but also have a potential application at misleading eavesdroppers. The impacts of the control light peak power at the receiver on the decryption performance are also analysed, the results indicate that the decryption performance of the scheme has a good tolerance to the peak power fluctuation of control light at the receiver.

Potential proteomic alteration in the brain of Tg(SOD1*G93A)1Gur mice: A new pathogenesis insight of amyotrophic lateral sclerosis.

The pathogenesis of amyotrophic lateral sclerosis (ALS) remains unclear. The recent studies have suggested that the protein abnormalities could play some important roles in ALS because several protein mutations were found in individuals with this disease. However, proteins that are currently known to be associated with ALS only explain the pathogenesis of this disease in a minority of cases, thus, further screening is needed to identify other ALS-related proteins. In this study, we systematically analyzed and compared the brain proteomic alterations between a mouse model of ALS, the Tg(SOD1*G93A)1Gur model, and wild-type mice using isobaric tags for relative and absolute quantitation (iTRAQ) as well as bioinformatics methods. The results revealed some significant up- and downregulated proteins at the different developmental stages in the ALS-like mice as well as the possibly related cellular components, molecular functions, biological processes, and pathways in the development of ALS. Our results identified some possible proteins that participate in the pathogenesis of ALS as well as the cellular components that are damaged by these proteins, we additionally identified the molecular functions, the biological processes, and the pathways of these proteins as well as the molecules that are associated with these pathways. This study represents an important preliminary investigation of the role of proteomic abnormalities in the pathogenesis of ALS, both in human patients and other animal models. We present some novel findings that may serve as a basis for further investigation of abnormal proteins that are involved in the pathogenesis of ALS.

Passive ocean acoustic tomography in shallow water.

It has been demonstrated that an estimate of an empirical Green's function (EGF) can be extracted from the ocean ambient noise cross-correlation functions, which can provide an alternative method for ocean acoustic tomography. However, the requirement for a long recording time to obtain EGFs with a high signal-to-noise ratio limits the application. This article focuses on using array signal processing to accelerate the convergence rate of EGFs between two horizontally separated arrays. With the extracted EGFs and data assimilation, ocean sound speed profiles (SSPs) can be inverted every 2 h in shallow water. The experimental results indicate that the variation in ocean SSPs can be reconstructed with reasonable agreement using an average variance of 1.14 m/s over three months.

Expression and Distribution of Arylsulfatase B are Closely Associated with Neuron Death in SOD1 G93A Transgenic Mice.

The known proteins only explained the partial pathogenesis of amyotrophic lateral sclerosis (ALS). Therefore, this study aimed to search the novel proteins possibly involved in ALS. In this study, we analyzed the expression and distribution of the candidate protein arylsulfatase B (ARSB) in the different segments, anatomic regions, and neural cells of spinal cord at the different stages of the wild-type and [Cu/Zn] superoxide dismutase 1 (SOD1) G93A transgenic mice using the fluorescent immunohistochemistry and the western blot. The results revealed that the ARSB was extensively expressed and distributed in the entire spinal cord; the expression and distribution of ARSB was significantly different in the different regions of spinal cord, the anterior horn of gray matter (AHGM) was significantly more than that in the posterior horn of gray matter (PHGM) and significantly more than that in the central canal, and ARSB was mainly distributed in the microglia and neuron cells in the wild-type mice. The expression of ARSB significantly increased in other anatomic regions besides the thoracic PHGM, significantly decreased at the progression stage, occurred in the redistribution from the AHGM and the PHGM to the central canal at the onset and progression stages, and no any alteration of ARSB expression and distribution occurred between the different neural cells in the SOD1 G93A mice compared with the wild-type mice. The increase of ARSB expression and distribution followed with the increased of neuron death. Our data suggested that the abnormal expression and distribution of ARSB were closely associated with the neuron death in the SOD1 G93A transgenic mice.

Aldehyde Dehydrogenases 1A2 Expression and Distribution are Potentially Associated with Neuron Death in Spinal Cord of Tg(SOD1*G93A)1Gur Mice.

The pathogenesis of amyotrophic lateral sclerosis (ALS) has not been unclear yet, it might be associated with the abnormal expression and distribution of certain proteins. Aldehyde dehydrogenases 1A2 (ALDH1A2) was thought to be one of potential candidates. Therefore, in this study we observed and analyzed the alteration of the expression and distribution of ALDH1A2 in the spinal cord of wild-type (WT) and Tg(SOD1*G93A)1Gur mice. We compared the expression and distribution of ALDH1A2 in the different segments, anatomic regions and neural cells of spinal cord at the different stages of WT and Tg(SOD1*G93A)1Gur mice applied the methods of fluorescent immunohistochemistry and western blot. Results revealed that ALDH1A2 extensively expressed and distributed in the spinal cord of adult WT and Tg(SOD1*G93A)1Gur mice. The expression and distribution of ALDH1A2 in the white matter including the anterior, posterior and lateral funiculus were more than that in the gray matter including the central canal, the anterior and dorsal horn. ALDH1A2 majorly expressed and distributed in the astrocyte, microglial, oligodendrocyte and neuron cells. The ALDH1A2 expression significantly decreased and redistributed in some anatomic regions of spinal cord at the onset and progression stages of Tg(SOD1*G93A)1Gur mice. The expression decrease of ALDH1A2 followed with the increase of neuron cells death. This study suggested that the alteration of expression and distribution of ALDH1A2 was potentially associated with the pathogenesis of ALS.

Distributed Features of Vimentin-Containing Neural Precursor Cells in Olfactory Bulb of SOD1G93A Transgenic Mice: a Study about Resource of Endogenous Neural Stem Cells.

No any effective treatments can prevent from the motor neuron degeneration in amyotrophic lateral sclerosis (ALS) at present. In order to modulating the endogenous neural precursor cells (NPCs) to repairing the degenerative motor neurons in ALS, we studied the alteration of endogenous vimentin-containing NPCs in olfactory bulb (OB) at the different stages of SOD1 wlid-type and G93A transgenic mice. The results showed that the vimentin-containing cells (VCCs) were mainly distributed in the glomerular layer (Gl), the accessory OB (AOB), the OB core, the granular cell layer (GRO) and the mitral cell layer (MI)+the internal plexiform layer (IPL) of the OB of adult mice. Almost all VCCs in Gl, OB core and GRO were the GFAP positive cells. Almost all VCCs in AOB were the Oligo-2 positive cells. Fewer VCCs in MI+IPL were the NeuN positive cells. VCCs significantly increased in the OB core and Gl of adult OB at the pre-onset, onset and progression stages of ALS-like G93A transgenic disease, particularly in OB core. All increased VCCs were the GFAP positive cells. Our data suggested that there extensively existed the endogenous vimentin-containing NPCs in the OB of adult mice, which was a potential resource of neural stem cells, they could differentiate into astrocyte, oligodendrocyte and neuron cells, were a potential astrocyte neuroregenerative response in adult OB in the ALS-like disease, were a potential pathway to repair the degenerated motor neurons.

An egg shell-like retroperitoneal pseudocyst.

Retroperitoneal pseudocysts are rare entities. Egg shell-like calcified retroperitoneal pseudocyst is rarer. We report a 75-year-old woman with an egg shell-like calcified retroperitoneal pseudocyst. Subsequently, the calcified pseudocyst was dissected and excised completely through laparoscopy via a retroperitoneal approach.