OPERATIONAL EFFICIENCY IN THE U.S. AIRLINE INDUSTRY: AN EMPIRICAL INVESTIGATION OF POST-DEREGULATION ERA

The purpose of this paper is threefold: (1) to examine the operational efficiency of U.S. airlines after the deregulation of 1978; (2) to investigate whether operational efficiency is associated with changes in financial position of firms in the industry and (3) to study if there is an observable pattern in the efficiency measures for large and small airlines. The results indicate that small U.S. airlines record higher scores than large U.S. airlines in four out of five efficiency measures examined. The exception is in the category of allocative efficiency where large airlines exhibit more optimal input mix of resources that their smaller counterparts. This superior mix of resources is consistent with cost minimization. In addition, the analysis shows that higher overall efficiency measures are associated with higher net profit margins of the airlines in the sample, while higher allocative efficiency seems to correlate with higher return on equity."U.S. airlines, efficiency, performance

Workplace factors associated with mental health of healthcare workers during the COVID-19 pandemic: an international cross-sectional study

BACKGROUND: The association of workplace factors on mental health of healthcare workers (HCWs) during the COVID-19 pandemic needs to be urgently established. This will enable governments and policy-makers to make evidence-based decisions. This international study reports the association between workplace factors and the mental health of HCWs during the pandemic. METHODS: An international, cross-sectional study was conducted in 41 countries. The primary outcome was depressive symptoms, derived from the validated Patient Health Questionnaire-2 (PHQ-2). Multivariable logistic regression identified factors associated with mental health outcomes. Inter-country differences were also evaluated. RESULTS: A total of 2,527 responses were received, from 41 countries, including China (n=1,213; 48.0%), UK (n=891; 35.3%), and USA (n=252; 10.0%). Of all participants, 1343 (57.1%) were aged 26 to 40 years, and 2021 (80.0%) were female; 874 (34.6%) were doctors, and 1367 (54.1%) were nurses. Factors associated with an increased likelihood of depressive symptoms were: working in the UK (OR=3.63; CI=[2.90-4.54]; p<0.001) and USA (OR=4.10; CI=[3.03-5.54]), p<0.001); being female (OR=1.74; CI=[1.42-2.13]; p<0.001); being a nurse (OR=1.64; CI=[1.34-2.01]; p<0.001); and caring for a COVID-19 positive patient who subsequently died (OR=1.20; CI=[1.01-1.43]; p=0.040). Workplace factors associated with depressive symptoms were: redeployment to Intensive Care Unit (ICU) (OR=1.67; CI=[1.14-2.46]; p=0.009); redeployment with perceived unsatisfactory training (OR=1.67; CI=[1.32-2.11]; p<0.001); not being issued with appropriate personal protective equipment (PPE) (OR=2.49; CI=[2.03-3.04]; p<0.001); perceived poor workplace support within area/specialty (OR=2.49; CI=[2.03-3.04]; p<0.001); and perceived poor mental health support (OR=1.63; CI=[1.38-1.92]; p<0.001). CONCLUSION: This is the first international study, demonstrating that workplace factors, including PPE availability, staff training pre-redeployment, and provision of mental health support, are significantly associated with mental health during COVID-19. Governments, policy-makers and other stakeholders need to ensure provision of these to safeguard HCWs’ mental health, for future waves and other pandemics

Biomechanical evaluation of immediate stability with rectangular versus cylindrical interbody cages in stabilization of the lumbar spine

BACKGROUND: Recent cadaver studies show stability against axial rotation with a cylindrical cage is marginally superior to a rectangular cage. The purpose of this biomechanical study in cadaver spine was to evaluate the stability of a new rectangular titanium cage design, which has teeth similar to the threads of cylindrical cages to engage the endplates. METHODS: Ten motion segments (five L2-3, five L4-5) were tested. From each cadaver spine, one motion segment was fixed with a pair of cylindrical cages (BAK, Sulzer Medica) and the other with paired rectangular cages (Rotafix, Corin Spinal). Each specimen was tested in an unconstrained state, after cage introduction and after additional posterior translaminar screw fixation. The range of motion (ROM) in flexion-extension, lateral bending, and rotation was tested in a materials testing machine, with +/- 5 Nm cyclical load over 10 sec per cycle; data from the third cycle was captured for analysis. RESULTS: ROM in all directions was significantly reduced (p < 0.05) with both types of cages. There was no significant difference in reduction of ROM in flexion-extension (p = 0.6) and rotation (p = 0.92) between the two cage groups, but stability in lateral bending was marginally superior with the rectangular cages (p = 0.11). Additional posterior fixation further reduced the ROM significantly (p < 0.05) in most directions in both cage groups, but did not show any difference between the cage groups. CONCLUSIONS: There was no significant difference in immediate stability in any direction between the threaded cylindrical cage and the new design of the rectangular cage with endplate teeth

Percutaneous suction and irrigation for the treatment of recalcitrant pyogenic spondylodiscitis.

The primary management of pyogenic spondylodiscitis is conservative. Once the causative organism has been identified, by blood culture or biopsy, administration of appropriate intravenous antibiotics is started. Occasionally patients do not respond to antibiotics and surgical irrigation and debridement is needed. The treatment of these cases is challenging and controversial. Furthermore, many affected patients have significant comorbidities often precluding more extensive surgical intervention. The aim of this study is to describe early results of a novel, minimally invasive percutaneous technique for disc irrigation and debridement in pyogenic spondylodiscitis.This article is freely available via Open Access. Click on the Additional Link above to access the full-text via the publisher's sit

The Effect of Ion-Channel Guiding on the Chaotic Electron Trajectories in a Free Electron Laser

It has been confirmed that when the equilibrium self-fields were taken into account, the motion of an electron in a helical wiggler with axial mag-netic field may be chaotic. In this paper, the effect of an ion-channel guiding on the chaotic electron trajectories is analyzed. It is shown that the ion--channel guiding may modify the chaotic electron trajectories. It is also found that when the parameter ε, i.e. ε = ω2pb/4ω 2 c, is increased, the den-sity of the ion-channel guiding, i.e. αi = ω 2 pi/4

The Effect of Ion-Channel Guiding on the Chaotic Electron Trajectories in a Free Electron Laser

It has been confirmed that when the equilibrium self-fields were taken into account, the motion of an electron in a helical wiggler with axial magnetic field may be chaotic. In this paper, the effect of an ion-channel guiding on the chaotic electron trajectories is analyzed. It is shown that the ion-channel guiding may modify the chaotic electron trajectories. It is also found that when the parameter ε, i.e. ε=ω$\text{}_{pb}^{2}$/4ω$\text{}_{c}^{2}$, is increased, the density of the ion-channel guiding, i.e. α$\text{}_{i}$=ω$\text{}_{pi}^{2}$/4ω$\text{}_{c}^{2}$, must be increased to keep the modification of the chaotic motion. The chaotic trajectories for constant parameter ε and increased density of the ion-channel guiding are presented. Numerical calculations are used to find the intersection between steady state group I and group II and resonance curves. Poincaré surface-of-section maps are generated to demonstrate the chaotic electron trajectories with axial magnetic field and its modification in the presence of an ion-channel guiding