Coherent Subcycle Optical Shock from a Superluminal Plasma Wake.

We propose exploiting the superluminal plasma wake for coherent Cherenkov radiation by injecting a relativistic electron beam (REB) into a plasma with a slowly varying density up-ramp. Using three-dimensional particle-in-cell and far-field time-domain radiation simulations, we show that an isolated subcycle pulse is coherently emitted towards the Cherenkov angle by bubble-sheath electrons successively at the rear of the REB-induced superluminal plasma wake. A theoretical model based on a superluminal current dipole has been developed to interpret such coherent radiation, and agrees well with the simulation results. This radiation has ultrashort attosecond-scale duration and high intensity, and exhibits excellent directionality with ultralow angular divergence and stable carrier envelope phase. Its intensity increases with the square of the propagation length and its central frequency can be easily tuned over a wide range, from the far infrared to the ultraviolet.

Branching of High-Current Relativistic Electron Beam in Porous Materials.

Propagation of high-current relativistic electron beam (REB) in plasma is relevant to many high-energy astrophysical phenomena as well as applications based on high-intensity lasers and charged-particle beams. Here, we report a new regime of beam-plasma interaction arising from REB propagation in medium with fine structures. In this regime, the REB cascades into thin branches with local density a hundred times the initial value and deposits its energy 2 orders of magnitude more efficiently than that in homogeneous plasma, where REB branching does not occur, of similar average density. Such beam branching can be attributed to successive weak scatterings of the beam electrons by the unevenly distributed magnetic fields induced by the local return currents in the skeletons of the porous medium. Results from a model for the excitation conditions and location of the first branching point with respect to the medium and beam parameters agree well with that from pore-resolved particle-in-cell simulations.

Nanoscale Electrostatic Modulation of Mega-Ampere Electron Current in Solid-Density Plasmas.

Transport of high-current relativistic electron beams in dense plasmas is of interest in many areas of research. However, so far the mechanism of such beam-plasma interaction is still not well understood due to the appearance of small time- and space-scale effects. Here we identify a new regime of electron beam transport in solid-density plasma, where kinetic effects that develop on small time and space scales play a dominant role. Our three-dimensional particle-in-cell simulations show that in this regime the electron beam can evolve into layered short microelectron bunches when collisions are relatively weak. The phenomenon is attributed to a secondary instability, on the space- and timescales of the electron skin depth (tens of nanometers) and few femtoseconds of strong electrostatic modulation of the microelectron current filaments formed by Weibel-like instability of the original electron beam. Analytical analysis on the amplitude, scale length, and excitation condition of the self-generated electrostatic fields is clearly validated by the simulations.

Treatment of male breast cancer: meta-analysis of real-world evidence.

BACKGROUND: Breast cancer is rare in men and managed by extrapolating from breast cancer in women. The clinicopathological features of male breast cancer, however, differ from those of female breast cancer. Because clinical trials are rare, the synthesis of real-world data is one method of integrating sufficient evidence on the optimal treatment for this patient population. METHODS: PubMed, Embase, and Cochrane Library databases were searched. Clinical studies were included if they evaluated the treatments of interest in male breast cancer; these evaluations included breast-conserving surgery (BCS) versus mastectomy, postmastectomy radiation therapy versus no radiation, the accuracy of sentinel lymph node biopsy (SLNB), and a comparison of various endocrine therapies. RESULTS: Forty studies were retrieved. The pooled estimate of overall survival (OS) revealed no difference between BCS and mastectomy groups. Postmastectomy radiation to the chest wall significantly increased OS relative to no postmastectomy radiation (hazard ratio (HR) 0.67, 95 per cent confidence interval 0.54 to 0.84). The pooled estimates of identification and false-negative rates of SLNB were 97.4 and 7.4 per cent respectively. Tamoxifen treatment was associated with significantly increased OS compared with no tamoxifen intake (HR 0.62, 0.41 to 0.95). CONCLUSION: Identification and false-negative rates for SLNB were comparable to those in female breast cancer. Breast-conserving surgery can be effective and safe; postmastectomy radiation to the chest wall and 5-year tamoxifen treatment improves survival.

Reduction of postural nasal resistance following oropharyngeal surgery in patients with moderate-severe obstructive sleep apnea.

BACKGROUND: Patients with obstructive sleep apnea (OSA) have elevated nasopharyngeal resistances due to increased turbulent airflow. The study aims to investigate the effect of oropharyngeal surgery on nasal resistance in patients with various severity levels of OSA. METHODOLOGY: Patients with greater or equal to 5 events hourly on the apnea-hypopnea index (AHI) were enrolled. Patients with retropalatal obstruction underwent uvulopalatopharyngoplasty, while patients with concurrent retrolingual obstruction under- went uvulopalatopharyngoplasty (UPPP) plus tongue base suspension. Before surgery and after surgery, subjective outcomes were assessed using a visual analog scale (VAS), and objective outcomes were assessed using overnight polysomnography and rhinomanometry. The limitation of the study was that UPPP instead of expansion sphincter pharyngoplasty was performed in this study. RESULTS: Sixty-two patients were enrolled, while 30 patients were diagnosed as mild OSA (group Mild) and 32 patients were mo- derate-severe OSA (group MS). The preoperative VAS of nasal obstruction in recumbency during sleep was significantly reduced after surgery in group MS. However, no significant differences between preoperative and postoperative VAS were found in group Mild. The postoperative anterior and posterior total nasal resistances (TNR) in sitting and supine positions were not significantly different from those before surgery in group. In contrast, the postoperative posterior TNR in supine position was 0.292±0.301(Pa/ cm3/s), compared with 0.425±0.343(Pa/cm3/s) preoperatively. CONCLUSIONS: Oropharyngeal surgery improves nasal obstruction during sleep and lowers the supine TNR measured in poste- rior rhinomanometry in patients with moderate-severe OSA. Oropharyngeal surgery is a possible treatment for postural nasal obstruction in patients with moderate-severe OSA.

Chitosan films promote formation of olfactory neurospheres and differentiation of olfactory receptor neurons.

BACKGROUND: Olfactory dysfunction significantly impairs the life quality of patients. Therefore, a model needs to be developed for anosmia. Chitosan is a biodegradable natural polysaccharide that has been widely studied for regenerative purposes in the nervous system. However, whether chitosan promotes differentiation of olfactory receptor neurons or regulates formation of neurospheres in the olfactory system remains unexplored. METHODOLOGY: Olfactory neuroepithelial cells were isolated from embryonic wistar rats on day 17, and cultured on controls and chitosan films for 12 days. The effects of treatment were assessed using immunocytochemistry, quantitative polymerase chain reaction and western blots following culturing. The substrate of poly-L-lysine-co-laminin was adopted as a control. RESULTS: In contrast to the flat layer on controls, olfactory neuroepithelial cells form olfactory neurospheres on chitosan films with steadily increasing diameter. The olfactory neurospheres contain basal cells, as well as immature and mature olfactory receptor neurons. The expression level of olfactory marker protein is higher on chitosan films than those on controls in gene and protein levels, and the olfactory transduction elements also express a similar trend. Mature olfactory receptor neurons are found predominantly at the periphery of the olfactory neurospheres. CONCLUSIONS: Chitosan films not only facilitate formation of olfactory neurospheres, but also promote differentiation of olfactory receptor neurons. Chitosan is a potential biomaterial to establish an in vitro culture model to treat olfactory dysfunction in future.

Effects of comorbidity and medication use on the haemodynamic status during office-based laryngeal procedures: A prospective cohort study.

OBJECTIVE: Office-based laryngeal procedures (OBLPs) are emerging as effective alternative modalities for vocal disorders. This study systematically investigates the haemodynamic status of patients, specifically focusing on the potential effects of underlying comorbidity and medication use. DESIGN: Prospective cohort study. SETTING: Tertiary referral centre. PARTICIPANTS: We prospectively recruited 214 consecutive patients who received OBLPs during January-December 2015. All procedures were performed under local anaesthesia without sedation, in an upright (sitting) position. MAIN OUTCOME MEASURES: We measured heart rate (HR), systolic and diastolic blood pressure, and oxygen saturations at baseline (before procedure), immediately after local anaesthesia to the pharynx and larynx, immediately after completing of procedure, and 20 minutes after the procedure. RESULTS: Systolic, diastolic blood pressures and HR all significantly increased after local anaesthesia, and gradually decreased after the procedure (P<.01). Oxygen concentration remained unchanged. Patients with comorbidity and those receiving vasoactive medications showed significantly higher perioperative blood pressures than the other patients (P<.05), but the trend remained similar. Prominent hypertension (systolic ≥160 mm Hg or diastolic ≥100 mm Hg) was noted in 17 patients, more commonly in patients with older age, higher baseline blood pressures and receiving vasoactive medications. Only 2% of patients with normal baseline measurements developed prominent hypertension perioperatively. Tachycardia (HR≥100 bpm) developed in 22 patients, more frequently in patients with higher baseline HRs, and perceiving greater discomforts. CONCLUSION: This study revealed that routine haemodynamic monitoring may not be necessary for all the OBLPs, but should be considered for older patients, those with higher baseline blood pressure or HR, sensitive patients who might be more susceptible to perioperative discomfort, and those receiving vasoactive medications.

Production of high-angular-momentum electron beams in laser-plasma interactions.

It was shown that in the interactions of ultra-intense circularly polarized laser pulse with the near-critical plasmas, the angular momentum can be transferred efficiently from the laser beam to electrons through the resonance acceleration process. The transferred angular momentum increases almost linearly with the acceleration time t_{a} when the electrons are resonantly accelerated by the laser field. In addition, it is shown analytically that the averaged angular momentum of electrons is proportional to the laser amplitude a_{L}, and the total angular momentum of the accelerated electron beam is proportional to the square of the laser amplitude a_{L}^{2} for a fixed parameter of n_{e}/n_{c}a_{L}. These results are verified by three-dimensional particle-in-cell simulations. This regime provides an efficient and compact alternative for the production of high angular momentum electron beams, which may have many potential applications in condensed-matter spectroscopy, new electron microscopes, and bright x-ray vortex generation.

Relativistic laser hosing instability suppression and electron acceleration in a preformed plasma channel.

The hosing processes of a relativistic laser pulse, electron acceleration, and betatron radiation in a parabolic plasma channel are investigated in the direct laser acceleration regime. It is shown that the laser hosing instability would result in the generation of a randomly directed off-axis electron beam and radiation source with a large divergence angle. While employing a preformed parabolic plasma channel, the restoring force provided by the plasma channel would correct the perturbed laser wave front and thus suppress the hosing instability. As a result, the accelerated electron beam and the emitted photons are well guided and concentrated along the channel axis. The employment of a proper plasma density channel can stably guide the relativistically intense laser pulse and greatly improve the properties of the electron beam and radiation source. This scheme is of great interest for the generation of high quality electron beams and radiation sources.

Brilliant petawatt gamma-ray pulse generation in quantum electrodynamic laser-plasma interaction.

We show a new resonance acceleration scheme for generating ultradense relativistic electron bunches in helical motions and hence emitting brilliant vortical γ-ray pulses in the quantum electrodynamic (QED) regime of circularly-polarized (CP) laser-plasma interactions. Here the combined effects of the radiation reaction recoil force and the self-generated magnetic fields result in not only trapping of a great amount of electrons in laser-produced plasma channel, but also significant broadening of the resonance bandwidth between laser frequency and that of electron betatron oscillation in the channel, which eventually leads to formation of the ultradense electron bunch under resonant helical motion in CP laser fields. Three-dimensional PIC simulations show that a brilliant γ-ray pulse with unprecedented power of 6.7 PW and peak brightness of 1025 photons/s/mm2/mrad2/0.1% BW (at 15 MeV) is emitted at laser intensity of 1.9 × 1023 W/cm2.

Assessment of carotid artery intima-media thickness in patients with obstructive sleep apnoea.

OBJECTIVE: This study compares the carotid intima-media thickness (CIMT) in different severity of obstructive sleep apnoea (OSA) patients and assesses the role of OSA in carotid artery vasculopathy with control of multiple co-morbidities. STUDY DESIGN: Prospective case-control study. SETTING: Tertiary referral centre. PARTICIPANTS: This study recruited 36 volunteers without the complaints of sleep-disordered breathing, 27 patients with mild-moderate OSA and 39 patients with severe OSA. MAIN OUTCOME MEASURES: The CIMT was measured using a Toshiba Aplio 500 ultrasound system (Otawara, Japan) with a 5-14 MHz L probe. RESULTS: Bilateral and mean CIMT in healthy control, mild-moderate OSA and severe OSA were 0.69 ± 0.14, 0.72 ± 0.24 and 0.94 ± 0.33, respectively (P < 0.01 in anova test). Post hoc tests show that the severe OSA group had significantly higher mean CIMT than the control and mild-moderate OSA groups (P < 0.01). With the cut-off as 1 mm, the increased risks of cardiovascular disease (CVD) for mild-moderate and severe OSA were 11% and 39%, respectively, while no patient in the healthy control group was at risk of CVD. Multivariate linear regression could not prove that OSA itself was an independent factors for increased CIMT (mild-moderate OSA ß: 0, [-0.12, 0.13]; severe OSA ß: 0.08, [-0.06, 0.22], both P > 0.05) after adjusting age, hypertension and body mass index. CONCLUSION: Automated measurement of the CIMT can be a useful tool for CVD risk assessment in patients with OSA. Severity of OSA may be an intermediate factor between multiple co-morbidities and carotid atherosclerotic change.

Controlling multiple filaments by relativistic optical vortex beams in plasmas.

Filamentation dynamics of relativistic optical vortex beams (OVBs) propagating in underdense plasma is investigated. It is shown that OVBs with finite orbital angular momentum (OAM) exhibit much more robust propagation behavior than the standard Gaussian beam. In fact, the growth rate of the azimuthal modulational instability decreases rapidly with increase of the OVB topological charge. Thus, relativistic OVBs can maintain their profiles for significantly longer distances in an underdense plasma before filamentation occurs. It is also found that an OVB would then break up into regular filament patterns due to conservation of the OAM, in contrast to a Gaussian laser beam, which in general experiences random filamentation.

Characteristics of betatron radiation from direct-laser-accelerated electrons.

Betatron radiation from direct-laser-accelerated electrons is characterized analytically and numerically. It is shown here that the electron dynamics is strongly dependent on a self-similar parameter S(≡n_{e}/n_{c}a_{0}). Both the electron transverse momentum and energy are proportional to the normalized amplitude of laser field (a_{0}) for a fixed value of S. As a result, the total number of radiated photons scales as a_{0}^{2}/sqrt[S] and the energy conversion efficiency of photons from the accelerated electrons scales as a_{0}^{3}/S. The particle-in-cell simulations agree well with the analytical scalings. It is suggested that a tunable high-energy and high-flux radiation source can be achieved by exploiting this regime.

Energetic electron-bunch generation in a phase-locked longitudinal laser electric field.

Energetic electron acceleration processes in a plasma hollow tube irradiated by an ultraintense laser pulse are investigated. It is found that the longitudinal component of the laser field is much enhanced when a linear polarized Gaussian laser pulse propagates through the plasma tube. This longitudinal field is of π/2 phase shift relative to the transverse electric field and has a π phase interval between its upper and lower parts. The electrons in the plasma tube are first pulled out by the transverse electric field and then trapped by the longitudinal electric field. The trapped electrons can further be accelerated to higher energy in the presence of the longitudinal electric field. This acceleration mechanism is clearly illustrated by both particle-in-cell simulations and single particle modelings.

Mitigating the relativistic laser beam filamentation via an elliptical beam profile.

It is shown that the filamentation instability of relativistically intense laser pulses in plasmas can be mitigated in the case where the laser beam has an elliptically distributed beam profile. A high-power elliptical Gaussian laser beam would break up into a regular filamentation pattern-in contrast to the randomly distributed filaments of a circularly distributed laser beam-and much more laser power would be concentrated in the central region. A highly elliptically distributed laser beam experiences anisotropic self-focusing and diffraction processes in the plasma channel ensuring that the unstable diffractive rings of the circular case cannot be produced. The azimuthal modulational instability is thereby suppressed. These findings are verified by three-dimensional particle-in-cell simulations.

Empyema caused by Anaeroglobus geminates, a case report with literature review.

Little is known about the virulence and clinical impact on humans from infection with Anaeroglobus geminates, an anaerobic gram-negative coccus belonging to the family Veillonellaceae. We report the first case of an Anaeroglobus geminates invasive infection in humans characterized by pneumonia complicated with empyema. The pathogen was initially identified as Veillonella spp. by an automatic identification system (Becton-Dickinson and Company, Franklin Lakes, NJ, USA) and definitively identified following 16S ribosomal RNA gene sequence analysis. The patient was cured by surgical decortication and antimicrobial therapy. In this case, the combination of effective antibiotics, surgical intervention, and adequate drainage successfully cured the patient.

Metastatic Lung Cancer Presenting as Thoracic Empyema in an Old Patient.

An 83-year old male presented to the emergency department with productive cough and acute shortness of breath. Imaging, biochemical and microbiological studies of the pleural fluid indicated empyema. After antibiotic treatment and tube drainage, symptoms of the patient persisted and he received thoracoscopic decortication. His condition improved gradually, but histopathological examination showed metastatic adenocarcinoma of the lung. Clinicians are alerted to the possible association of malignant tumours and empyema in older patients.

Three-dimensional analysis of the surface registration accuracy of electromagnetic navigation systems in live endoscopic sinus surgery.

BACKGROUND: Studies on the performance of surface registration with electromagnetic tracking systems are lacking in both live surgery and the laboratory setting. This study presents the efficiency in time of the system preparation as well as the navigational accuracy of surface registration using electromagnetic tracking systems. METHODOLOGY: Forty patients with bilateral chronic paranasal pansinusitis underwent endoscopic sinus surgery after undergoing sinus computed tomography scans. The surgeries were performed under electromagnetic navigation guidance after the surface registration had been carried out on all of the patients. The intraoperative measurements indicate the time taken for equipment set-up, surface registration and surgical procedure, as well as the degree of navigation error along 3 axes. RESULTS: The time taken for equipment set-up, surface registration and the surgical procedure was 179 +- 23 seconds, 39 +- 4.8 seconds and 114 +- 36 minutes, respectively. A comparison of the navigation error along the 3 axes showed that the deviation in the medial-lateral direction was significantly less than that in the anterior-posterior and cranial-caudal directions. CONCLUSION: The procedures of equipment set-up and surface registration in electromagnetic navigation tracking are efficient, convenient and easy to manipulate. The system accuracy is within the acceptable ranges, especially on the medial-lateral axis.

Pattern dynamics and filamentation of femtosecond terawatt laser pulses in air including the higher-order Kerr effects.

Plasma defocusing and higher-order Kerr effects on multiple filamentation and pattern formation of ultrashort laser pulse propagation in air are investigated. Linear analyses and numerical results show that these two saturable nonlinear effects can destroy the coherent evolution of the laser field, and small-scale spatial turbulent structures rapidly appear. For the two-dimensional case, numerical simulations show that blow-up-like solutions, spatial chaos, and pseudorecurrence can appear at higher laser intensities if only plasma defocusing is included. These complex patterns result from the stochastic evolution of the higher- or shorter-wavelength modes of the laser light spectrum. From the viewpoint of nonlinear dynamics, filamentation can be attributed to the modulational instability of these spatial incoherent localized structures. Furthermore, filament patterns associated with multiphoton ionization of the air molecules with and without higher-order Kerr effects are compared.