GPU-accelerated three-dimensional reconstruction method of the Compton camera and its application in radionuclide imaging

A novel and fast three-dimensional reconstruction method for a Compton camera and its performance in radionuclide imaging is proposed and analyzed in this study. The conical surface sampling back-projection method with scattering angle correction(CSS-BP-SC) can quickly perform the back-projection process of the Compton cone and can be used to precompute the list-mode maximum likelihood expectation maximization(LM-MLEM). A dedicated parallel architecture was designed for the graphics processing unit acceleration of the back-projection and iteration stage of the CSS-BP-SC-based LM-MLEM. The imaging results of the two-point source Monte Carlo(MC) simulation demonstrate that by analyzing the full width at half maximum along the three coordinate axes, the CSS-BP-SC-based LM-MLEM can obtain imaging results comparable to those of the traditional reconstruction algorithm, that is, the simple back-projection-based LM-MLEM. The imaging results of the mouse phantom MC simulation and experiment demonstrate that the reconstruction results obtained by the proposed method sufficiently coincide with the set radioactivity distribution, and the speed increased by more than 664 times compared to the traditional reconstruction algorithm in the mouse phantom experiment. The proposed method will further advance the imaging applications of Compton cameras.

右美托咪定混合罗哌卡因腹横肌平面阻滞对腹腔镜下结直肠癌手术患者术后疼痛及免疫功能的影响

目的观察右美托咪定混合罗哌卡因行超声引导下腹横肌平面阻滞(TAPB)对腹腔镜下结直肠癌根治性切除术患者术后镇痛效果及免疫功能的影响。方法选择择期行腹腔镜下结直肠癌根治性切除术的患者60例,随机分为右美托咪定混合罗哌卡因TAPB组(DR组)、单纯罗哌卡因TAPB组(R组)和生理盐水TAPB对照组(C组),每组20例。各组患者均于麻醉诱导后行超声引导下TAPB,DR组给予右美托咪定1μg/kg混合0.375%罗哌卡因共40 mL,R组给予0.375%罗哌卡因40 mL,C组注入生理盐水40 mL,每侧各20 mL。于术前(T0)、术后2 h(T1)、24 h(T4)和48 h(T5)时抽取静脉血样,采用流式细胞仪测定T淋巴细胞亚群(CD3^+、CD4^+和CD8^+)和自然杀伤细胞(NK)水平;观察术后2 h(T1)、6 h(T2)、12 h(T3)、24 h(T4)和48 h(T5)的静息状态和运动状态下视觉模拟评分(VAS);记录术中丙泊酚、瑞芬太尼用量、术后首次下床时间、肛门排气时间及住院天数。结果与T0时比较,3组于T1、T4和T5时CD3^+、NK细胞活性均明显降低(P<0.05);C组于T1、T4和T5时而R组、DR组于T1、T4时,CD4^+活性均明显降低(P<0.05);与C组比较,R组和DR组于T1、T4时CD3^+细胞活性均明显升高(P<0.05);R组和DR组于T4时CD4^+、NK细胞活性均明显升高(P<0.05);DR组T5时NK细胞活性仍较C组明显升高(P<0.05)。与C组比较,R组于T2、T3时点、DR组T2、T3和T4时点活动时VAS评分均明显降低(P<0.05);与R组比较,DR组T3时点活动时VAS评分明显降低(P<0.05)。R组和DR组术中丙泊酚、瑞芬太尼用量均明显少于C组(P<0.05)。R组和DR组术后下床时间均明显早于C组,DR组肛门首次排气时间亦明显早于C组(P<0.05)。结论腹腔镜下结直肠癌根治性切除术采用右美托咪定混合罗哌卡因行TAPB可延长镇痛时间,明显降低术中麻醉药物用量,免疫抑制程度更轻,促进患者早期恢复。

Blood eosinophils and mortality in patients with acute respiratory distress syndrome: A propensity score matching analysis

BACKGROUND: The effect of blood eosinophils(EOSs) on mortality in acute respiratory distress syndrome(ARDS) patients and whether corticosteroids affect this effect are unclear.METHODS: The Medical Information Mart for Intensive Care III database(version 1.4) was used to extract data. Patients with ARDS were selected for inclusion. Cox regression models using the backward stepwise method and propensity score matching(PSM) were used to assess the relationship between blood EOS counts and 28-day mortality. RESULTS: A total of 2,567 patients with ARDS were included, and the 28-day mortality rate was 24.19%. The crude 28-day mortality was significantly lower in patients with EOS counts ≥2%(18.60% [85/457] vs. 25.40% [536/2,110], P=0.002) than in those with EOS counts <2%. In the Cox regression model, the EOS counts ≥2% showed a significant association with the decreased 28-day mortality(hazard ratio [HR] 0.731;95% confidence interval [95% CI] 0.581–0.921, P=0.008). In the corticosteroid non-use subgroup, EOS counts ≥2% was significantly related to decreased 28-day mortality(HR 0.697, 95% CI 0.535–0.909, P=0.008), but the result was not significant in the corticosteroid non-use subgroup model(P=0.860). A total of 457 well-matched pairs were obtained by a 1:1 matching algorithm after PSM. The 28-day mortality remained significantly lower in the EOS counts ≥2% group(18.60% [85/457] vs. 26.70% [122/457], P=0.003).CONCLUSIONS Higher EOS counts are related to lower 28-day mortality in ARDS patients, and this relationship can be counteracted by using corticosteroids.

Magnetized strange quark matter in the equivparticle model with both confinement and perturbative interactions

We investigated the properties of strange quark matter in an external strong magnetic field with both confinement and leading-order perturbative interactions considered. It was found that the leading-order perturbative interaction can stiffen the equation of state of magnetized quark matter, while the magnetic field lowers the minimum energy per baryon. By solving the Tolman–Oppenheimer–Volkoff equations, we obtain the internal structure of strange stars. The maximum mass of strange stars can be as large as 2 times the solar mass.

Bulk viscosity of interacting magnetized strange quark matter

The bulk viscosity of interacting strange quark matter in a strong external magnetic field B m with a real equation of state is investigated.It is found that interquark interactions can significantly increase the bulk viscosity,and the magnetic field B_(m) can cause irregular oscillations in both components of the bulk viscosity,ξ||(parallel to B_(m))and ξ⊥(perpendicular to B_(m)).A comparison with non-interacting strange quark matter reveals that when B_(m) is sufficiently large,ξ⊥is more affected by interactions than ξ||.Additionally,the quasi-oscillation of the bulk viscosity with changes in density may facilitate the for-mation of magnetic domains.Moreover,the resulting r-mode instability windows are in good agreement with observational data for compact stars in low-mass X-ray binaries.Specifically,the r-mode instability window for interacting strange quark matter in high magnetic fields has a minimum rotation frequency exceeding 1050 Hz,which may explain the observed very high spin frequency of a pulsar with V=1122 Hz.

右美托咪定联合综合体温保护对腔镜手术治疗老年恶性肿瘤患者苏醒期质量及免疫功能的影响

目的探讨右美托咪定联合综合体温保护对腔镜手术治疗老年恶性肿瘤患者苏醒期质量及免疫功能的影响。方法选择择期行腔镜手术治疗的老年恶性肿瘤患者90例,随机均分为3组:对照组(C组)、体温保护组(T组)和体温保护联合右美托咪定组(T-D组),每组30例。C组常规体温保护,T组和T-D组综合体温保护;T-D组麻醉诱导前10 min泵注右美托咪定0.5μg/kg。记录3组患者麻醉诱导开始时(T_(0))、手术开始30 min(T_(1))、60 min(T_(2))、90 min(T_(3))、120 min(T_(4))以及手术结束时(T_(5))的鼻咽温度;于T_(0)、术后2 h(T_(6))、24 h(T_(7))和48 h(T^(8))时抽取静脉血标本,测定T淋巴细胞亚群(CD3^(+)、CD4^(+)和CD8^(+))和自然杀伤细胞(NK cell)水平;记录患者术中麻醉药物用量及苏醒期质量指标。结果与T_(0)比较,C组T_(2)~T_(5)时点鼻咽温度均明显降低(P<0.05);与C组比较,T组和T-D组T_(2)~T_(5)时点鼻咽温度明显升高(P<0.05)。与T_(0)时点比较,C组、T组和T-D组T_(6)、T_(7)和T^(8)时点CD3^(+)和NK cell活性均明显降低(P<0.05);C组在T_(6)、T_(7)和T^(8)时点,T组和T-D组在T_(6)和T_(7)时点,CD4^(+)活性均明显降低(P<0.05)。与C组比较,T组和T-D组T_(6)和T_(7)时点CD3^(+)细胞活性均明显升高(P<0.05);T组在T_(7)时点,T-D组在T_(6)和T_(7)时点,CD4^(+)细胞活性均明显升高(P<0.05);T组在T_(7)时点,T-D组在T_(6)、T_(7)和T^(8)时点,NK cell活性均明显升高(P<0.05)。结论采用体温保护措施联合右美托咪定能够维持老年恶性肿瘤患者的体温稳定,减少围手术期意外低体温(IPH)的发生,并有效提高患者苏醒期质量,减轻免疫抑制程度,加速患者早期恢复。

Spatiotemporal patterns of non-point source nitrogen loss in an agricultural catchment

Non-point source nitrogen loss poses a risk to sustainable aquatic ecosystems. However, non-point sources, as well as impaired river segments with high nitrogen concentrations, are difficult to monitor and regulate because of their diffusive nature, budget constraints, and resource deficiencies. For the purpose of catchment management, the Bayesian maximum entropy approach and spatial regression models have been used to explore the spatiotemporal patterns of non-point source nitrogen loss. In this study, a total of 18 sampling sites were selected along the river network in the Hujiashan Catchment. Over the time period of 2008e2012, water samples were collected 116 times at each site and analyzed for non-point source nitrogen loss. The morphometric variables and soil drainage of different land cover types were studied and considered potential factors affecting nitrogen loss. The results revealed that, compared with the approach using the Euclidean distance, the Bayesian maximum entropy approach using the river distance led to an appreciable 10.1% reduction in the estimation error, and more than 53.3% and 44.7% of the river network in the dry and wet seasons, respectively, had a probability of non-point source nitrogen impairment. The proportion of the impaired river segments exhibited an overall decreasing trend in the study catchment from 2008 to 2012, and the reduction in the wet seasons was greater than that in the dry seasons. High nitrogen concentrations were primarily found in the downstream reaches and river segments close to the residential lands. Croplands and residential lands were the dominant factors affecting non-point source nitrogen loss, and explained up to 70.7%of total nitrogen in the dry seasons and 54.7% in the wet seasons. A thorough understanding of the location of impaired river segments and the dominant factors affecting total nitrogen concentration would have considerable importance for catchment management.

Single-nucleotide polymorphisms based genetic risk score in the prediction of pancreatic cancer risk

BACKGROUND Disease-related single nucleotide polymorphisms(SNPs)based genetic risk score(GRS)has been proven to provide independent inherited risk other than family history in multiple cancer types.AIM To evaluate the potential of GRS in the prediction of pancreatic cancer risk.METHODS In this case-control study(254 cases and 1200 controls),we aimed to evaluate the association between GRS and pancreatic ductal adenocarcinoma(PDAC)risk in the Chinese population.The GRS was calculated based on the genotype information of 18 PDAC-related SNPs for each study subject(personal genotyping information of the SNPs)and was weighted by external odd ratios(ORs).RESULTS GRS was significantly different in cases and controls(1.96±3.84 in PDACs vs 1.09±0.94 in controls,P<0.0001).Logistic regression revealed GRS to be associated with PDAC risk[OR=1.23,95%confidence interval(CI):1.13-1.34,P<0.0001].GRS remained significantly associated with PDAC(OR=1.36,95%CI:1.06-1.74,P=0.015)after adjusting for age and sex.Further analysis revealed an association of increased risk for PDAC with higher GRS.Compared with low GRS(<1.0),subjects with high GRS(2.0)were 99%more likely to have PDAC(OR:1.99,95%CI:1.30-3.04,P=0.002).Participants with intermediate GRS(1.0-1.9)were 39%more likely to have PDAC(OR:1.39,95%CI:1.03-1.84,P=0.031).A positive trend was observed(P trend=0.0006).CONCLUSION GRS based on PDAC-associated SNPs could provide independent information on PDAC risk and may be used to predict a high risk PDAC population.

Symmetry energy of strange quark matter and tidal deformability of strange quark stars

Research performed during the past decade revealed an important role of symmetry energy in the equation of state(EOS)of strange quark matter(SQM).By introducing an isospin-dependent term into the quark mass scaling,the SQM stability window in the equivparticle model was studied.The results show that a sufficiently strong isospin dependence C_(I)can significantly widen the SQM region of absolute stability,yielding results that simultaneously satisfy the constraints of the astrophysical observations of PSR J1614-2230 with 1.928±0.017 Mand tidal deformability 70≤Λ_(1:4)≤580 measured in the event GW170817.With increasing C_(I),the difference between the u,d,and s quark fractions for the SQM inβ-equilibrium becomes inconspicuous for C>0,leading to small isospin asymmetryδ,and further resulting in similar EOS and structures of strange quark stars(SQSs).Moreover,unlike the behavior of the maximum mass of ud QSs,which varies with C_(I)depending on the sign of the parameter C,the maximum mass of the SQSs decreases monotonously with increasing CI.

The Huashan risk calculators performed better in prediction of prostate cancer in Chinese population： a training study followed by a validation study

The performances of the Prostate Cancer Prevention Trial （PCPT） risk calculator and other risk calculators for prostate cancer （PCa） prediction in Chinese populations were poorly understood. We performed this study to build risk calculators （Huashan risk calculators） based on Chinese population and validated the performance of prostate-specific antigen （PSA）, PCPT risk calculator, and Huashan risk calculators in a validation cohort. We built Huashan risk calculators based on data from 1059 men who underwent initial prostate biopsy from January 2006 to December 2010 in a training cohort. Then, we validated the performance of PSA, PCPT risk calculator, and Huashan risk calculators in an observational validation study from January 2011 to December 2014. All necessary clinical information were collected before the biopsy. The results showed that Huashan risk calculators 1 and 2 outperformed the PCPT risk calculator for predicting PCa in both entire training cohort and stratified population （with PSA from 2.0 ng ml^-1 to 20.0 ng ml^-1）. In the validation study, Huashan risk calculator 1 still outperformed the PCPT risk calculator in the entire validation cohort （0.849 vs 0.779 in area under the receiver operating characteristic curve [AUC]） and stratified population. A considerable reduction of unnecessary biopsies （approximately 30%） was also observed when the Huashan risk calculators were used. Thus, we believe that the Huashan risk calculators （especially Huashan risk calculator 1） may have added value for predicting PCa in Chinese population. However, these results still needed further evaluation in larger populations.

Prostate volume does not provide additional predictive value to prostate health index for prostate cancer or clinically significant prostate cancer:results from a multicenter study in China

To evaluate whether prostate volume(PV)would provide additional predictive utility to the prostate health index(phi)for predicting prostate cancer(PCa)or clinically significant prostate cancer,we designed a prospective,observational multicenter study in two prostate biopsy cohorts.Cohort 1 included 595 patients from three medical centers from 2012 to 2013,and Cohort 2 included 1025 patients from four medical centers from 2013 to 2014.Area under the receiver operating characteristic curves(AUC)and logistic regression models were used to evaluate the predictive performance of PV-based derivatives and models.Linear regression analysis showed that both total prostate-specific antigen(tPSA)and free PSA(fPSA)were significantly correlated with PV(all P<0.05).[-2]proPSA(p2PSA)was significantly correlated with PV in Cohort 2(P<0.001)but not in Cohort 1(P=0.309),while no significant association was observed between phi and PV.When combining phi with PV,phi density(PHID)and another phi derivative(PHIV,calculated as phi/PV°5)did not outperform phi for predicting PCa or clinically significant PCa in either Cohort 1 or Cohort 2.Logistic regression analysis also showed that phi and PV were independent predictors for both PCa and clinically significant PCa(all P<0.05);however,PV did not provide additional predictive value to phi when combining these derivatives in a regression model(all models vs phi were not statistically significant,all P>0.05).In conclusion,PV-based derivatives(both PHIV and PHID)and models incorporating PV did not improve the predictive abilities of phi for either PCa or clinically significant PCa.

Bulk viscosity for interacting strange quark matter and r-mode instability windows for strange stars

We investigate the bulk viscosity of strange quark matter in the framework of the equivparticle model,where analytical formulae are obtained for certain temperature ranges,which can be readily applied to those with various quark mass scalings.In the case of adopting a quark mass scaling with both linear confinement and perturbative interactions,the obtained bulk viscosity increases by 1-2 orders of magnitude compared with those in bag model scenarios.Such an enhancement is mainly due to the large quark equivalent masses adopted in the equivparticle model,which are essentially attributed to the strong interquark interactions and are related to the dynamical chiral symmetry breaki ng.Due to the high bulk viscosity,the predicted damping time of oscillatio ns for a can on ical 1.4 M⊙ strange star is less than one millisecond,which is shorter than previous findings.Consequently,the obtained r-mode instability window for the canonical strange stars well accommodates the observational frequencies and temperatures for pulsars in low-mass X-ray binaries(LMXBs).

Landau quantization and spin polarization of cold magnetized quark matter

The magnetic field and density behaviors of various thermodynamic quantities of strange quark matter under compact star conditions are investigated in the framework of the thermodynamically self-consistent quasiparticle model.For individual species,a larger number density n_(i) leads to a larger magnetic field strength threshold that aligns all particles parallel or antiparallel to the magnetic field.Accordingly,in contrast to the finite baryon density effect which reduces the spin polarization of magnetized strange quark matter,the magnetic field effect leads to an enhancement of it.We also compute the sound velocity as a function of the baryon density and find the sound velocity shows an obvious oscillation with increasing density.Except for the oscillation,the sound velocity grows with increasing density,similar to the zero-magnetic field case,and approaches the conformal limit V_(s)^(2)=1/3 at high densities from below.