Longitudinal evaluation of time related femoral neck narrowing after metal-on-metal hip resurfacing

AIM: To track the short-term neck narrowing changes in Birmingham metal-on-metal hip resurfacing(MOMHR) patients. METHODS: Since 2001, the Center for Hip and Knee Replacement started a registry to prospectively collect data on hip and knee replacement patients. From June 2006 to October 2008, 139 MOMHR were performed at our center by two participate surgeons using Birmingham MOMHR prosthesis(Smith Nephew, United States). It is standard of care for patients to obtain low, anteriorposterior(LAP) pelvis radiographs immediately after MOMHR procedure and then at 3 mo, 1 year and 2 year follow up office visits. Inclusion criteria for the present study included patients who came back for follow up office visit at above mentioned time points and got LAP radiographs. Exclusion criteria include patients who missed more than two follow up time points and those with poor-quality X-rays. Two orthopaedic residency trained research fellows reviewed the X-rays independently at 4 time points, i.e., immediate after surgery, 3 mo, 1 year and 2 year. Neck-to-prosthesis ratio(NPR) was used as main outcome measure. Twenty cases were used as subjects to identify the reliability between two observers. An intraclass correlation coefficient at 0.8 was considered as satisfied. A paired t-test was used to evaluate the significant difference between different time points with P < 0.05 considered to be statistically significant.RESULTS: The mean NPRs were 0.852 ± 0.056, 0.839 ± 0.052, 0.835 ± 0.051, 0.83 ± 0.04 immediately, 3 mo, 1 year and 2 years post-operatively respectively. At 3 mo, NPR was significantly different from immediate postoperative X-ray(P < 0.001). There was no difference between 3 mo and 1 year(P = 0.14) and 2 years(P = 0.53). Femoral neck narrowing(FNN) exceeding 10% of the diameter of the neck was observed in only 4 patients(5.6%) at two years follow up. None of these patients developed a femoral neck fracture(FNF). CONCLUSION: Femoral neck narrowing after MOMHR occurred as early as 3 mo postoperatively, and stabilized thereafter. Excessive FNN was not common in patients within the first two years of surgery and was not correlated with risk of FNF.

Bandgap narrowing in the layered oxysulfide semiconductor Ba_3Fe_2O_5Cu_2S_2: Role of FeO_2 layer

A new layered Cu-based oxychalcogenide Ba_3Fe_2O_5Cu_2S_2 has been synthesized and its magnetic and electronic properties were revealed. Ba_3Fe_2O_5Cu_2S_2 is built up by alternatively stacking [Cu_2S_2]^（2-） layers and iron perovskite oxide[（FeO_2）（BaO）（FeO_2）]^（2-）layers along the c axis that are separated by barium ions with Fe^（3＋） fivefold coordinated by a square-pyramidal arrangement of oxygen. From the bond valence arguments, we inferred that in layered CuC h-based（Ch =S, Se, Te） compounds the ＋3 cation in perovskite oxide sheet prefers a square pyramidal site, while the lower valence cation prefers the square planar sites. The studies on susceptibility, transport, and optical reflectivity indicate that Ba_3Fe_2O_5Cu_2S_2 is an antiferromagnetic semiconductor with a Ne′el temperature of 121 K and an optical bandgap of 1.03 eV. The measurement of heat capacity from 10 K to room temperature shows no anomaly at 121 K. The Debye temperature is determined to be 113 K. Theoretical calculations indicate that the conduction band minimum is predominantly contributed by O 2p and 3 d states of Fe ions that antiferromagnetically arranged in FeO_2 layers. The Fe 3d states are located at lower energy and result in a narrow bandgap in comparison with that of the isostructural Sr_3Sc_2O_5Cu_2S_2.

Observation of linewidth narrowing due to a spontaneously generated coherence effect

We investigate the resonance fluorescence spectrum of an atomic three-level ladder system driven by two laser fields. We show that such a system emulates to a large degree a V-type atom with parallel dipole moments-the latter being a system that exhibits spontaneously generated coherence and can display ultrasharp spectral lines. We find a suitable energy scheme in a SSRb atom and experimentally observe the narrowing of the central peak in a rubidium atomic beam. The corresponding spectrum can convindngiy demonstrate the existence of spontaneously generated coherence.

Absorptive reduction and width narrowing in Λ-type atoms confined between two dielectric walls

This paper investigates the absorptive reduction and the width narrowing of electromagnetically induced transparency （EIT） in a thin vapour film of A-type atoms confined between two dielectric walls whose thickness is comparable with the wavelength of the probe field. The absorptive lines of the weak probe field exhibit strong reductions and very narrow EIT dips, which mainly results from the velocity slow-down effects and transient behaviour of atoms in a confined system. It is also shown that the lines are modified by the strength of the coupling field and the ratio of L/λ, with L the film thickness and λthe wavelength of the probe field. A simple robust recipe for EIT in a thin medium is achievable in experiment.

Cavity linewidth narrowing with dark-state polaritons

We present a quantum-theoretical treatment of cavity linewidth narrowing with intracavity electromagnetically in- duced transparency （EIT）. By means of intracavity EIT, the photons in the cavity are in the form of cavity polaritons： bright-state polariton and dark-state polariton. Strong coupling of the bright-state polariton to the excited state induces an effect known as vacuum Rabi splitting, whereas the dark-state polariton decoupled from the excited state induces a narrow cavity transmission window. Our analysis would provide a quantum theory of linewidth narrowing with a quantum field pulse.

Narrowing Gap Between Rich and Poor

Inequality in distribution has become an issue of public concern in China. Incomes of the Chinese people have grown year after year ever since the reform and opening era began in the late 1970s. Meanwhile, the income gap between urban and rural residents has widened constantly, from 1.8:1 in the mid-1980s to 3.2:1 in 2003. In a report entitled Analysis and Forecast of China's Social Conditions 2004-2005, experts with the Chinese Academy of Social Sciences listed the widening income gaps as the second most serious of the six problems China is facing. The report notes that such gaps have kept widening not only between individual workers in the same profession but also between workers in different industries and regions. In view of this, the national economic work conference held in early January called for effort to improve the order of income distribution and readjust the distribution of national wealth in an appropriate manner. How to view the problem of inequality in distribution as we see now? How the divide of the rich and the poor affects the improvement of human rights? What should be done to narrow the gap between the rich and the poor? We have dis- cussed these questions with two leading social scientists in China, Sun Guohua, pro- fessor of law at the Renmin University of China and Prof. Hu Angang of Qinghua University, a noted expert in study of the conditions in China.

Degenerate cascade fluorescence: Optical spectral-line narrowing via a single microwave cavity

For a three-level atom, two nondegenerate(even microwave and optical) electric dipole transitions are usually allowed;for either of these, the fluorescence spectra are well-described in terms of spontaneous transitions from a triplet of dressed sublevels to an adjacent lower-lying triplet. When the three dressed sublevels are equally spaced from each other, a remarkable feature known as degenerate cascade fluorescence takes place, which displays a five-peaked structure. We show that a single cavity can make all the spectral lines extremely narrow, whether they arise from cavity-coupled or cavity-free transitions. This effect is based on intrinsic cascade lasing feedback and makes it possible to use a single microwave cavity(even a bad cavity) to narrow the spectral lines in the optical frequency regime.

Linewidth narrowing in self-injection-locked on-chip lasers

Stable laser emission with narrow linewidth is of critical importance in many applications,including coherent communications,LIDAR,and remote sensing.In this work,the physics underlying spectral narrowing of self-injection-locked on-chip lasers to Hz-level lasing linewidth is investigated using a composite-cavity structure.Heterogeneously integrated III–V/SiN lasers operating with quantum-dot and quantum-well active regions are analyzed with a focus on the effects of carrier quantum confinement.The intrinsic differences are associated with gain saturation and carrier-induced refractive index,which are directly connected with 0-and 2-dimensional carrier densities of states.Results from parametric studies are presented for tradeoffs involved with tailoring the linewidth,output power,and injection current for different device configurations.Though both quantum-well and quantum-dot devices show similar linewidth-narrowing capabilities,the former emits at a higher optical power in the self-injection-locked state,while the latter is more energy-efficient.Lastly,a multi-objective optimization analysis is provided to optimize the operation and design parameters.For the quantum-well laser,minimizing the number of quantum-well layers is found to decrease the threshold current without significantly reducing the output power.For the quantum-dot laser,increasing the quantum-dot layers or density in each layer increases the output power without significantly increasing the threshold current.These findings serve to guide more detailed parametric studies to produce timely results for engineering design.

Linewidth narrowing in free-space-running diamond Brillouin lasers

This study analyzes the linewidth narrowing characteristics of free-space-running Brillouin lasers and investigates the approaches to achieve linewidth compression and power enhancement simultaneously.The results show that the Stokes linewidth behavior in a free-space-running Brillouin laser cavity is determined by the phase diffusion of the pump and the technical noise of the system.Experimentally,a Stokes light output with a power of 22.5 W and a linewidth of 3.2 kHz was obtained at a coupling mirror reflectivity of 96%,which is nearly 2.5 times compressed compared with the linewidth of the pump(7.36 kHz).In addition,the theorical analysis shows that at a pump power of 60Wand a coupling mirror reflectivity of 96%,a Stokes output with a linewidth of 1.6 kHz and up to 80%optical conversion efficiency can be achieved by reducing the insertion loss of the intracavity.This study provides a promising technical route to achieve high-power ultra-narrow linewidth special wavelength laser radiations.

Negative bias temperature instability induced single event transient pulse narrowing and broadening

The effect of negative bias temperature instability （NBTI） on a single event transient （SET） has been studied in a 130 nm bulk silicon CMOS process based on 3D TCAD device simulations. The investigation shows that NBTI can result in the pulse width and amplitude of SET narrowing when the heavy ion hits the PMOS in the high-input inverter; but NBTI can result in the pulse width and amplitude of SET broadening when the heavy ion hits the NMOS in the low-input inverter. Based on this study, for the first time we propose that the impact of NBTI on a SET produced by the heavy ion hitting the NMOS has already been a significant reliability issue and should be of wide concern, and the radiation hardened design must consider the impact of NBTI on a SET.

Considerations of dopant-dependent bandgap narrowing for accurate device simulation in abrupt HBTs

Heavy doping of the base in HBTs brings about a bandgap narrowing （BGN） effect, which modifies the intrinsic carrier density and disturbs the band offset, and thus leads to the change of the currents. Based on a thermionic-field-diffusion model that is used to the analyze the performance of an abrupt HBT with a heavydoped base, the conclusion is made that, although the BGN effect makes the currents obviously change due to the modification of the intrinsic carrier density, the band offsets disturbed by the BGN effect should also be taken into account in the analysis of the electrical characteristics of abrupt HBTs. In addition, the BGN effect changes the bias voltage for the onset of Kirk effects.

975 nm multimode semiconductor lasers with high-order Bragg diffraction gratings

The 975 nm multimode diode lasers with high-order surface Bragg diffraction gratings have been simulated and calcu-lated using the 2D finite difference time domain(FDTD)algorithm and the scattering matrix method(SMM).The periods and etch depth of the grating parameters have been optimized.A board area laser diode(BA-LD)with high-order diffraction grat-ings has been designed and fabricated.At output powers up to 10.5 W,the measured spectral width of full width at half maxi-mum(FWHM)is less than 0.5 nm.The results demonstrate that the designed high-order surface gratings can effectively nar-row the spectral width of multimode semiconductor lasers at high output power.

Generation of nanosecond 2.65μm pulses and pulse narrowing in fiber-bulk Ho3+:YAG laser pumped gain-switched Cr^2+:Cd Se laser

The generation of mid-infrared pulsed lasers was achieved in a Ho3+:YAG laser pumped gain-switched Cr^2+:Cd Se laser system with the shortest pulse duration of 4.15 ns.With a pump pulse duration of 50 ns and pump power of 2.7 W,the gain-switched Cr^2+:Cd Se laser achieved over 10 times pulse narrowing,obtaining the maximum peak power of 5.7 k W.The optical-to-optical conversion efficiency was 3.7%,which could be further improved with better crystal surface polishing quality.The laser central wavelength was measured to be 2.65μm with a bandwidth(FWHM)of 50 nm.In addition,the parameter optimization for suppressing the pulse tail was discussed,while the long cavity and high output transmissivity contributed to obtaining the single-peak pulses.

Accurate structural descriptor enabled screening for nitrogen and oxygen vacancy codoped TiO_(2) with a large bandgap narrowing

Nitrogen(N)doping has been widely adopted to improve the light absorption of TiO_(2).However,the newly introduced N-2p states are largely localized thus barely overlap with O-2p states in the valence band of TiO_(2),resulting in a shoulder-like absorption edge.To realize an apparent overlap between N-2p and O-2p states,charge compensation between N^(3-)and O^(2-)via electron transfer from oxygen vacancies(VO)to N dopants is one possible strategy.To verify this,in numerous doping configurations of N/VO-codoped anatase TiO_(2),we identified two types of VOposition independent N-dopant spatial orderings by efficient screening enabled with a newly designed structural descriptor.Compared with others,these two types of the N-dopant spatial orderings are highly beneficial for charge compensation to produce an apparent overlap between N-2p and O-2p states,therefore achieving a large bandgap narrowing.Furthermore,the two types of the N-dopant spatial orderings can also be generalized to N/VO-codoped rutile TiO_(2)for bandgap narrowing.

Tunable single-longitudinal-mode SOA-based fiber laser based on the spectral narrowing effect in a dispersion-shifted fiber

A tunable single-longitudinal-mode（SLM） semiconductor optical amplifier（SOA）-based fiber laser based on a dispersion-shifted fiber（DSF） is proposed and successfully demonstrated. SLM operation is obtained due to the spectral narrowing effect resulting from inverse four-wave mixing in a DSF. A tunable optical filter performs wavelength selection function. By inserting a length of DSF in the laser cavity, SLM lasing can possibly be obtained when laser oscillation is stably established after traveling through the DSF many roundtrips. Stable tunable SLM oscillation with a signal-to-noise ratio as high as 65 dB over a wavelength range of about 35 nm is achieved experimentally, and each spectral linewidth is less than 6.5 kHz.

Priceless Lessons

I am a passionate and dedicated teacher who embarked on a life-changing journey to Xiamen to teach students in a foreign land.With a heart full of enthusiasm and a mind brimming with knowledge,I embraced the challenges and rewards of teaching in a new cultural setting.Xiamen,a vibrant coastal city in southeastern China,welcomed me with its bustling streets,traditional architecture,and warm hospitality.As I navigated the city’s narrow alleys and busy markets,I marvelled at the blend of modernity and ancient traditions that defined Xiamen’s unique charm.

Angiographic differentiation of systolic narrowing of the left anterior descending coronary artery in hypertrophic cardiomyopathy from myocardial bridges

To the Editor： I read with great interest the case report of multiple myocardial bridges affecting both coronary arteries in a patient with hypertrophic cardiomyopathy. However, I differ with the authors in their interpretation of the coronary arteriograms.

A Comprehensive Study on the digestive Endoscopic Technique and Narrow-Band Imaging for Early Gastric Cancer Screening

Objective:To explore the implementation of gastrointestinal endoscopy technology and endoscopic narrow-band imaging(NBI)in the early screening of gastric cancer and to observe and study their application effects.Methods:During the period from March 2023 to August 2023,312 patients who received gastroscopy in the Kunming Guandu District People’s Hospital were selected,and they underwent both conventional gastroscopy and endoscopic NBI,with clinicopathological tissue biopsy serving as the gold standard.The application value for early screening of gastric cancer was observed and analyzed.Results:The scoring data showed that the clarity of gastric mucosal glandular tube structure,microvascular structure clarity,and lesion contour scoring data of conventional gastroscopy were lower than those of the NBI technology(P<0.05).The screening rate of pathological biopsy in 312 patients was 18.59%(58 cases).Conventional gastroscopy showed a screening rate of 11.53%(36 cases),while NBI technology examined a screening rate of 17.63%(55 cases),and the two-by-two comparison of the screening rate data of the three groups was not statistically significant(P>0.05).The sensitivity,specificity,accuracy,positive predictive value,and negative predictive value of conventional gastroscopy appeared to be lower than those of NBI technology(P<0.05).Conclusion:In the early screening of gastric cancer,endoscopic NBI technology can be applied to patients.Compared with conventional gastroscopy,it provides a clearer visualization of the structure of the gastric mucosal glandular structure and microvascular structure,with a certain screening rate.Additionally,its sensitivity,specificity,accuracy,positive predictive value,and negative predictive value are higher,demonstrating outstanding effectiveness.

Cultural Exchanges Narrowing the Distance between the Peoples of China and the United States

Library of Congress,built in the year 1800,has the largest collection in the world,with over 1 million books in Chinese.However,in the 1960s-1970s,there were only about 300,000 books in Chinese.The leap from 300000 to 1 million,along with development of China-U.S.relations from the establishment of diplomatic relations to maturing relationship,which also reflects the rising interest of the U.S.circles