On the conjecture of Kevin Walker

In 1985 Kevin Walker in his study of topology of polygon spaces raised an interesting conjecture in the spirit of the well-known question "Can you hear the shape of a drum?" of Marc Kac. Roughly, Walker's conjecture asks if one can recover relative lengths of the bars of a linkage from intrinsic algebraic properties of the cohomology algebra of its configuration space. In this paper we prove that the conjecture is true for polygon spaces in R^3. We also prove that for planar polygon spaces the conjecture holds is several modified forms: (a) if one takes into account the action of a natural involution on cohomology, (b) if the cohomology algebra of the involution's orbit space is known, or (c) if the length vector is normal. Some of our results allow the length vector to be non-generic, the corresponding polygon spaces have singularities. Our main tool is the study of the natural involution and its action on cohomology. A crucial role in our proof plays the solution of the isomorphism problem for monoidal rings due to J. Gubeladze

Grade 4 renal injury: current trend of management and future directions

AbstractThe management of blunt renal trauma has been evolving. The past management largely based on American Association for Surgery of Trauma (AAST) grading system, i.e. necessitated a computed tomography (CT) scan. Although the CT scan use is increasing and becomes the standardized mode of investigation, AAST grading no longer plays the sole role in the decision of surgical interventions. Two case reports of blunt renal trauma managed successfully by conservative methods are presented.Case one was an 18 year-old boy who had a fall when riding a motorbike at 20 km/h with a helmet and full protective equipments. He was landed by his left flank onto a rock. Contrast abdominal CT revealed a 4 cm, grade III splenic tear and a grade IV left kidney injury with large perirenal haematoma. His international severity score (ISS) was 34. He was managed conservatively with bed rest and frequent serum haemoglobin monitoring. Subsequent CT with delayed contrast revealed stable perirenal haematoma with urine extravasation which was consistent with a grade IV renal injury. Case two was a 40 year-old male who had a motor bike accident on a racetrack when he was driving at 80 to 100 km/h, wearing a helmet. He lost control and hit onto the sidewall of the racetrack. Contrast abdominal CT revealed a grade IV left renal injury with a large urine extravasation. His renal injury was managed conservatively with interval delayed phase CT of the abdomen. A repeat CT on abdomen was performed five months after the initial injury which revealed no residual urinoma.In this study, moreover, a review of the literature to the management of blunt renal trauma was conducted to demonstrate the trend of increasing conservative management of such traumas. Extra radiological parameters may guide future decision making. However, the applicability of data may be limited until randomized trials are available

A Case Study of Success Factors for Data Warehouse Implementation and Adoption in Sales Planning

We present the case of the successful implementation of a data warehouse for support of the sales planning process in an Austrian company. We investigate the factors that contributed to the success of the project. The key findings of this case study are as follows. First, highly-qualified external consultants may compensate insufficient qualification of internal staff. Of particular importance in that case is communication between internal staff and external consultants. Second, user training compensates a lack of (perceived) usability of the software. Resistance of initially overwhelmed users may be overcome through training sessions. Finally, rather than acquire functionality that is not required, companies should ensure customizability of the acquired software, which is often more important than a plethora of features

A method for optimal fit of patient-specific fracture fixation plates

Anatomically pre-contoured fracture fixation plates are a treatment option for bone fractures. A well-fitting plate can be used as a tool for anatomical reduction of the fractured bone. However, recent studies showed that some plates fit poorly for many patients due to considerable shape variations between bones of the same anatomical site. Therefore, the plates have to be manually fitted and deformed by surgeons to fit each patient optimally. The process is time-intensive and labor-intensive, and could lead to adverse clinical implications such as wound infection or plate failure. This paper proposes a new iterative method to simulate the patient-specific deformation of an optimally fitting plate for pre-operative planning purposes. We further demonstrate the validation of the method through a case study. The proposed method involves the integration of four commercially available software tools, Matlab, Rapidform2006, SolidWorks, and ANSYS, each performing specific tasks to obtain a plate shape that fits optimally for an individual tibia and is mechanically safe. A typical challenge when crossing multiple platforms is to ensure correct data transfer. We present an example of the implementation of the proposed method to demonstrate successful data transfer between the four platforms and the feasibility of the method

Unconventional gas: potential energy market impacts in the European Union

In the interest of effective policymaking, this report seeks to clarify certain controversies and identify key gaps in the evidence-base relating to unconventional gas. The scope of this report is restricted to the economic impact of unconventional gas on energy markets. As such, it principally addresses such issues as the energy mix, energy prices, supplies, consumption, and trade flows. Whilst this study touches on coal bed methane and tight gas, its predominant focus is on shale gas, which the evidence at this time suggests will be the form of unconventional gas with the most growth potential in the short- to medium-term. This report considers the prospects for the indigenous production of shale gas within the EU-27 Member States. It evaluates the available evidence on resource size, extractive technology, resource access and market access. This report also considers the implications for the EU of large-scale unconventional gas production in other parts of the world. This acknowledges the fact that many changes in the dynamics of energy supply can only be understood in the broader global context. It also acknowledges that the EU is a major importer of energy, and that it is therefore heavily affected by developments in global energy markets that are largely out of its control.JRC.F.3-Energy securit

Injectable autologous chondrocyte implantation (ACI) in acetabular cartilage defects—three-year results

To evaluate the clinical outcome after arthroscopic matrix-associated injectable autologous chondrocyte implantation (ACI) in patients with large full-thickness acetabular cartilage defects. ACI was performed in young patients with full-thickness acetabular cartilage defects >= 2 cm(2) in a two-step arthroscopic procedure. The patients were followed closely with clinical examinations and pre- and postoperative scores. The modified Harris Hip Score (mHHS), iHOT33 questionnaire (iHOT33) and the Subjective Hip Value (SHV) were surveyed. Demographic patient data was evaluated for influencing factors for the pre- and postoperative results. Thirty-two consecutive cases (4 female, 28 male, mean age 33 years) were included. The average defect size was 4.9 (range: 2-6) cm(2). They were followed at 6, 12, 24 and 36 months postoperatively. Patients had improved significantly from 64 to 91 points (P < 0.001) in the mHHS, from 44% to 86% (P < 0.001) in the iHOT33 and from 54% to 87% (P < 0.001) in the SHV. No surgery related complications were noted. Cell cultivation failed in two cases (7%) and the patients decided for a repeated harvesting of cartilage cylinders followed by a successful ACI. Patients age and size of the cartilage defect showed no significant correlation with the pre- or postoperative results. Injectable ACI is a reliable procedure treating full-thickness acetabular cartilage defects leading to promising results 3 years postoperatively with a significant increase in all scores despite large acetabular cartilage defects in the weight-bearing zone