[A cohort study on the association between resting heart rate and the risk of new-onset heart failure]

Objective: To prospectively explore the relationship between resting heart rate (RHR) and risk of new-onset heart failure. Methods: It was a prospective cohort study. People who attended the physical examination of Kailuan Group Company in 2006 and with complete electrocardiography (ECG) recordings were eligible for this study. A total of 88 879 participants aged 18 years old or more who were free of arrhythmia, a prior history of heart failure and were not treated with β-blocker were included. Participants were divided into 5 groups according to the quintiles of RHR at baseline (Q(1) group, 40-60 beats/minutes (n=18 168) ; Q(2) group, 67-70 beats/minutes (n=18 970) ; Q(3) group, 71-74 beats/minutes (n=13 583) ; Q(4) group, 75-80 beats/minutes (n=22 739) ; and Q(5) group,>80 beats/minutes (n=15 419) ) .The general clinical data and laboratory test results were collected. The outcome was the first occurrence of heart failure at the end of follow-up (December 31, 2016) .We used Cox regression model to examine the association between RHR and the risk of new-onset heart failure. Hazard ratio (HR) with 95% confidence intervals (CI) were calculated using Cox regression modeling. Results: Among the included patients 68 411 participants were male, mean age was (51.0±12.3) years old, and RHR was (74±10) beats/minutes. Statistically significant differences among the RHR quintiles were found for the following variables: age, gender, systolic blood pressure, diastolic blood pressure, triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, fasting blood glucose, body mass index, the level of high-sensitivity C-reactive protein, education status, physical activity, smoking status, drinking status, history of diabetes, history of hypertension and history of use antihypertensive drugs (all P<0.01) . Higher RHR was linked with higher prevalence of diabetes, hypertension history, and higher systolic blood pressure, diastolic blood pressure and FBG levels (all P<0.01). After a mean follow-up of 9.5 years, the incidence of new-onset heart failure in Q(1), Q(2), Q(3), Q(4) and Q(5) groups was 1.60%(290/18 168), 1.36%(258/18 970), 1.80%(245/13 583), 1.76%(400/22 739) and 2.35%(362/15 419),respectively (P<0.01) . The person-year incidence of heart failure in Q(1), Q(2), Q(3), Q(4) and Q(5) groups was 1.7, 1.5, 1.9, 1.9 and 2.6 per 1 000 person-years respectively. Compared with the Q(2) group, multivariate analysis with adjustment for major traditional cardiovascular risk factors showed that HRs of Q(3),Q(4),and Q(5) group were 1.23 (95%CI 1.03-1.48, P<0.05) , 1.19 (95%CI 1.01-1.41, P<0.05) , 1.39 (95%CI 1.18-1.65, P<0.01) , respectively. In the absence of hypertension, diabetes, smoking and acute myocardial infarction, the Cox regression model showed that compared with Q(2) group, the HR of new-onset heart failure in Q(5) group was 1.58 (95%CI 1.02-2.45, P<0.05) . Conclusion: Increased RHR is associated with increased risk of new-onset heart failure in this cohort.

[Association between resting heart rate trajectory pattern and risk of cardiovascular and cerebrovascular diseases]

Objective: To examine whether the long-term resting heart rate (RHR) pattern can predict the risk of cardiovascular and cerebrovascular diseases (CVDs). Methods: This prospective cohort study included 63 040 participants who took part in the health examination in 2006 and one of the health examinations on 2008 or 2010 and were free of myocardial infarction, stroke, arrhythmia, cancer and not treated with β-recepter blocker. The outcomes were the first occurrence of myocardial infarction and stroke during the follow up ended on December 31, 2015. RHRs were measured in 2006, 2008, and 2010. We used latent mixture modeling SAS Proc procedure to identify RHR trajectories. We identified 4 distinct RHR trajectory patterns based on the data derived from 2006 and on the pattern change during 2006 to 2010 (low-stable, moderate-stable, moderate-increasing, elevated-decreasing). Collected the general clinical data of the patients. Cox regression model was used to determine the association between RHR trajectory patterns and the risk of CVDs during follow up. Hazard ratio (HR) with 95% confidence intervals (CI) were calculated using Cox regression modeling. Results: There were statistical significance among the 4 distinct RHR trajectory patterns on the following variables: age, gender, smoking status, drinking status, physical activity, education status, history of use antihypertensive drugs, history of hypertension,history of diabetes, body mass index, triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, fasting blood glucose, and the level of high-sensitivity C-reactive protein (all P<0.01). The moderate-increasing pattern experienced the highest risk of developing stroke and CVDs among all 4 patterns. The cumulative incidence of cerebral infarction, cerebral hemorrhage and CVDs in the order of low-stable trajectory, moderate-stable trajectory and moderate-increasing trajectory. The cumulative incidences of cerebral infarction, cerebral hemorrhage and CVDs in elevated-decreasing trajectory group were significantly lower than those in moderate-increasing trajectory group, but higher than those in moderate-stable trajectory group. Compared to the low-stable pattern, adjusted HR was 1.3 (95%CI 1.0-1.6) for the moderate-increasing pattern after adjustment for potential confounders. Conclusion: Our study finds that individuals with moderate-increasing RHR trajectory pattern are associated with higher risk of cardiovascular and CVDs.

[Feasibility of screw placement on posterior occipital condyle assisted by occipital tangent angulation]

Objective: To investigate the practicability of occipital tangent angle in assisting posterior occipital condylar screw placement and to verify the safety and accuracy of self-made screw placement device for auxiliary screw. Methods: Occipito-cervical region specimens of 12 adult corpses were selected and scanned by thin-cut CT examination.The three-dimensional reconstruction of occipital and atlas was simulated for each specimen, and 3-matic software was used to measure the setting parameters, including occipital tangent angle, head obliquity, internal inclination angle, length of the screw and the distance from the inferior margin of hypoglossal canal to the screw axis.Using the self-designed occipital condylar screw placement device, combined with occipital tangent angle, internal inclination angle and insertion point, the posterior occipital condylar screw specimen was inserted with nails with assisting tool.The occipito-cervical region was reconstructed and scanned by thin-cut CT examination again after the operation to measuring the parameters of screw placement after actual screwing.The paired t test was used to compare the parameters of screw placement before and after operation. Results: Pre-operative three dimensional reconstruction of occipital condyle screw showed that the head obliquity was 5.3°±0.9°, the tangent angle was 14.9°±3.7°, the internal inclination angle was 28.1°±5.9°, and the length of screw insertion was (21.4±1.7) mm respectively; the distance from the inferior margin of hypoglossal canal to the screw axis was (4.74±0.36) mm.There was no significant difference in the parameters of analogue nailing between the left and right occipital condyles before the operation (t=-1.32, -0.48, 0.10, 0.23, 0.09, all P>0.05). The occipital condylar screw was safely implanted with screw placement device.The screw was located in the ideal nail insertion channel after operation by CT scan evaluation, without any injury to the hypoglossal canal, the atlanto-occipital articular surface and other structure.After the operation, the actual nailing parameters were measured: the head inclination angle was 5.2°±0.7°, the tangent angle was 15.1°±3.2°, the internal inclination angle was 28.2°±4.2°, the length of screw insertion was (21.5±1.7) mm, the distance from the inferior margin of hypoglossal canal to the screw axis was (4.54±0.29) mm.There was no significant difference between the left and right side in the actual screw placement parameters (t=-0.77, 0.82, 0.56, 0.22, 0.21, all P>0.05). It was found that there was no significant differences in the head obliquity, the occipital tangent angle, the internal inclination angle, length of screw entry, and the distance from the inferior margin of hypoglossal canal to the screw axis before and after the operation (t=0.56, -0.47, -0.18, -0.70, 1.89, all P>0.05). Conclusion: The occipital tangent angle can be measured directly in the process of posterior occipital condyle screw insertion to guide occipital condylar screw insertion, and the self-made occipital condylar screw placement device can effectively combine the three parameters: occipital tangent angle, head inclination angle and insertion point, which can improve the safety of posterior occipital condylar screw insertion.

Active control of bright electron beams with RF optics for femtosecond microscopy

A frontier challenge in implementing femtosecond electron microscopy is to gain precise optical control of intense beams to mitigate collective space charge effects for significantly improving the throughput. Here, we explore the flexible uses of an RF cavity as a longitudinal lens in a high-intensity beam column for condensing the electron beams both temporally and spectrally, relevant to the design of ultrafast electron microscopy. Through the introduction of a novel atomic grating approach for characterization of electron bunch phase space and control optics, we elucidate the principles for predicting and controlling the phase space dynamics to reach optimal compressions at various electron densities and generating conditions. We provide strategies to identify high-brightness modes, achieving ∼100 fs and ∼1 eV resolutions with 10⁶ electrons per bunch, and establish the scaling of performance for different bunch charges. These results benchmark the sensitivity and resolution from the fundamental beam brightness perspective and also validate the adaptive optics concept to enable delicate control of the density-dependent phase space structures to optimize the performance, including delivering ultrashort, monochromatic, high-dose, or coherent electron bunches.

Ultrafast diffraction and structural dynamics: the nature of complex molecules far from equilibrium

Studies of molecular structures at or near their equilibrium configurations have long provided information on their geometry in terms of bond distances and angles. Far-from-equilibrium structures are relatively unknown-especially for complex systems-and generally, neither their dynamics nor their average geometries can be extrapolated from equilibrium values. For such nonequilibrium structures, vibrational amplitudes and bond distances play a central role in phenomena such as energy redistribution and chemical reactivity. Ultrafast electron diffraction, which was developed to study transient molecular structures, provides a direct method for probing the nature of complex molecules far from equilibrium. Here we present our ultrafast electron diffraction observations of transient structures for two cyclic hydrocarbons. At high internal energies of approximately 4 eV, these molecules display markedly different behavior. For 1,3,5-cycloheptatriene, excitation results in the formation of hot ground-state structures with bond distances similar to those of the initial structure, but with nearly three times the average vibrational amplitude. Energy is redistributed within 5 ps, but with a negative temperature characterizing the nonequilibrium population. In contrast, the ring-opening reaction of 1,3-cyclohexadiene is shown to result in hot structures with a CC bond distance of over 1.7 A, which is 0.2 A away from any expected equilibrium value. Even up to 400 ps, energy remains trapped in large-amplitude motions comprised of torsion and asymmetric stretching. These studies promise a new direction for studying structural dynamics in nonequilibrium complex systems.

Direct imaging of transient molecular structures with ultrafast diffraction

Ultrafast electron diffraction (UED) has been developed to study transient structures in complex chemical reactions initiated with femtosecond laser pulses. This direct imaging of reactions was achieved using our third-generation apparatus equipped with an electron pulse (1.07 +/- 0.27 picoseconds) source, a charge-coupled device camera, and a mass spectrometer. Two prototypical gas-phase reactions were studied: the nonconcerted elimination reaction of a haloethane, wherein the structure of the intermediate was determined, and the ring opening of a cyclic hydrocarbon containing no heavy atoms. These results demonstrate the vastly improved sensitivity, resolution, and versatility of UED for studying ultrafast structural dynamics in complex molecular systems.