Non-inversion conservation tillage as an underestimated driver of tillage erosion

Tillage erosion is a widely underestimated process initiating soil degradation especially in case of large agricultural fields located in rolling topography. It is often assumed that, conservation, non-inversion tillage causes less tillage erosion than conventional inversion tillage. In this study, tillage erosion was determined on three paired plots comparing non-inversion chisel versus inversion mouldboard tillage. The experiments were performed at three sites in Northeast Germany with gentle, moderate, and steep slope, while tillage depth (0.25 m) and speed (≈ 6 km h^-1) were kept constant during all experiments. The results indicate that non-inversion tillage produces significantly more soil movement compared to inversion tillage. The soil translocation distance was by a factor of 1.3-2.1 larger in case of chisel tillage. The largest difference in translocation distance and tillage transport coefficient (k_til) was found on the gentle slope exhibiting the lowest soil cohesion. Our results together with an evaluation of k_til values derived from literature and standardised for 0.25 m tillage depth contradict the general assumption that non-inversion tillage reduces tillage erosion. In tillage erosion dominated areas, non-inversion tillage applied with high tillage speed and depth potentially increases tillage erosion and fails its purpose to serve as soil conservation measure.

[Endoprosthetic tumor replacement : Reconstruction of the extensor mechanism and complications]

BACKGROUND

The reconstruction of the extensor mechanism around the knee is an essential part of tumorresection and tumor arthroplasty in orthopaedic oncology for functional rehabilitation of quality of life and daily activities.

OBJECTIVES

Operative procedures, treatment options and management of complications with reconstruction of the extensor mechanism after tumor resection around the knee depend on the type of arthroplasty.

MATERIALS AND METHODS

Description of the different treatment option for extensor deficiency divided into infra- and suprapatellar modalities.

RESULTS

The operative procedure is always an individual decision depending on the size of the tumor and its localisation. The extensor mechanism is reconstructed with autogenic, allogenic or synthetic material in combination with tumor arthroplasty.

CONCLUSIONS

Extensor reconstruction (supra-/infrapatellar) is an essential part of tumor resection and tumor arthroplasty around the knee. Often, low functional results and high levels of complications (arthrofibrosis, rerupture extensor mechanism, periprosthetic joint infection) are seen in these highly demanding cases in orthopaedic oncology.

[Gluteal insufficiency: Pathogenesis, Diagnosis and Therapy]

INTRODUCTION

Gluteal insufficiency is a common and challenging complaint. New concepts in pathobiomechanics and improved clinical understanding of chronic gluteal dysfunction have unmasked gluteus medius (GMed) tears as an underlying cause of enhanced trochanteric pain syndrome (GTPS). These tears are often missed or misdiagnosed as bursitis, but lead to prolonged chronic peritrochanteric pain. Clinic: The clinical signs are often dull pain on the lateral hip aspect, reduced hip abduction strength with positive Trendelenburg testing and a tendency for the leg to external rotation, as the internal rotation strength is reduced.

IMAGING

Radiography and ultrasound may be used to confirm the diagnosis, whereas MRI is the modality of choice for imaging. Compensatory hypertrophy of the tensor fascia latae muscle (TFL) and fatty involution (especially of the GMed) are also seen.

THERAPY

Conservative treatment regimens for partial thickness tears involve hip joint centering and strengthening of abductor muscles, sparing TFL. Failed conservative treatment and full thickness tears are treated surgically. Partial tears can be addressed endoscopically with suture anchors for tendon footprint reconstruction. Larger tears involving the anterior and/or lateral facets of the tendon or failed conservative treatment are repaired with minimally invasive open reduction techniques. Double row suture anchor techniques provide anatomical tendon footprint reconstruction. Postoperative rehabilitation is prolonged, due to high acting forces in the peritrochanteric region, and needs to be carried out under professional surveillance.

CONCLUSION

Reconstruction of gluteal tendon tears is often the only solution in the treatment of chronic hip pain due to gluteal insufficiency. Available data suggest that reduction in pain and restoration of abduction power can be achieved in mid-term follow-up.

Invasive floating macrophytes reduce greenhouse gas emissions from a small tropical lake

Floating macrophytes, including water hyacinth (Eichhornia crassipes), are dominant invasive organisms in tropical aquatic systems, and they may play an important role in modifying the gas exchange between water and the atmosphere. However, these systems are underrepresented in global datasets of greenhouse gas (GHG) emissions. This study investigated the carbon (C) turnover and GHG emissions from a small (0.6 km²) water-harvesting lake in South India and analysed the effect of floating macrophytes on these emissions. We measured carbon dioxide (CO₂) and methane (CH₄) emissions with gas chambers in the field as well as water C mineralization rates and physicochemical variables in both the open water and in water within stands of water hyacinths. The CO₂ and CH₄ emissions from areas covered by water hyacinths were reduced by 57% compared with that of open water. However, the C mineralization rates were not significantly different in the water between the two areas. We conclude that the increased invasion of water hyacinths and other floating macrophytes has the potential to change GHG emissions, a process that might be relevant in regional C budgets.

[Surgical technique: reconstruction of deficient extensor apparatus of the knee - a case report]

Injuries to the extensor apparatus of the knee are a rare but in case of their occurrence a serious injury. In the following discussion, the focus is on treatment of chronic patellar tendon tears. The aim of surgical treatment is the recovery of the active extension and full weight-bearing ability of the leg. The video presentation shows the operative treatment of a patient with a chronic extensor mechanism deficiency of the knee after multiple revision of a total knee arthroplasty due to periprosthetic infection and three-times occurrence of a patella tendon tear. A frame-shaped reinforcement between patella and tibial tuberosity by FiberTape® combined with a medial gastrocnemius flap was performed. This type of surgery is indicated in cases of large defects of the patellar tendon that cannot be treated with end-to-end suture or simple augmentation with autologous tendons (e.g. semitendinosus). In addition to augmentation of the tendon defect, cutaneous soft tissue defects around the knee and proximal lower leg can be covered. In general, the best treatment option is chosen according to size of the defect, the quality of the tendon tissue and possible previous surgery on the knee joint. There are no reports of large series of chronic patella tendon tears, but only isolated cases using a variety of techniques. In addition with low level of evidence, there is currently no established gold standard in the surgical treatment of insufficiencies of the extensor apparatus of the knee.

Nonsequential double recombination in intense laser fields

A second plateau in the harmonic spectra of laser-driven two-electron atoms is observed both in the numerical solution of a low-dimensional model helium atom and using an extended strong field approximation. It is shown that the harmonics well beyond the usual cutoff are due to the simultaneous recombination of the two electrons, which were emitted during different, previous half-cycles. The new cutoff is explained in terms of classical trajectories. Classical predictions and the time-frequency analysis of the ab initio quantum results are in excellent agreement. The mechanism corresponds to the inverse single photon double ionization process in the presence of a (low frequency) laser field.

Adiabatic approximation of the correlation function in the density-functional treatment of ionization processes

The ionization of a one-dimensional model helium atom in short laser pulses using time-dependent density-functional theory is investigated. We calculate ionization probabilities as a function of laser intensity by approximating the correlation function of the system adiabatically with an explicit dependence on the fractional number of bound electrons. For the correlation potential we take the derivative discontinuity at integer numbers of bound electrons explicitly into account. This approach reproduces ionization probabilities from the solution of the time-dependent Schrödinger equation, in particular, the so-called knee due to nonsequential ionization.