130,439 research outputs found
First-year experience with MICA technique: learning difficulties, mistakes, and results
No full textBACKGROUND: Hallux valgus is a very common forefoot disorder, first named by Carl Hueter (1871) as a condition with a static subluxation of the first metatarsophalangeal joint with lateral deviation of the great toe and medial deviation of the first metatarsal. It usually leads to pain and functional impairment of the foot. With the continuous evolution of technology and the idea to shift open Austin Akin osteotomy to MIS surgery, more recently Redfern and Vernois developed the Minimally Invasive Chevron Akin (MICA) technique. The use of this technique has been vastly studied by the authors, but to our knowledge there is a scarce literature production by independent authors reporting their experience in the use of this technique. The aim of the present study was to show our preliminary results in the use of MICA technique performed by the same surgeon during his first year of use, underlining the learning difficulties, mistakes and results achieved during this frame of time. METHODS: The MICA procedure was performed on 60 feet from July 2018 to July 2019. A follow-up of at least 11 months was achieved. The clinical outcome was measured through AOFAS Score. RESULTS: The mean patients age was 51.5 years old (range: from 36 to 72 years old). The mean AOFAS Score was 90.4, interestingly 24 patients (40% of the total of 60 patients) had AOFAS Score set over 90. CONCLUSIONS: MICA osteotomy marries percutaneous surgery with the Austin Akin osteotomy, that have been and are widely used for the treatment of hallux valgus. It is possible to achieve the good results of a well know surgery with a stable fixation and obtain all the goals of percutaneous surgery, such has limited pain, good postoperative range of motion and an overall positive experience of the patient. The learning curve, if the surgeon is correctly instructed, is steep, but the results are good since the first procedures. On the other hand, the complications/surgical errors reported are limited, easily resolvable and do not impact the overall positive results. (Cite this article as: Marcolli D, Pichierri I, Minoli C, Mazzotti A, Compagnoni R, Randelli PS. First-year experience with MICA technique: learning difficulties, mistakes, and results. Minerva Orthop 2024;75:7-13. DOI: 10.23736/S2784-8469.23.04330-4
Management of distal radius fractures: treatment protocol and functional results.
No full textDistal radius fractures are the most frequent lesions encountered during clinical practice. The treatment is controversial and still debated in the literature. For a correct management of these lesions many authors recently emphasised the importance of anatomical reduction, a stable fixation and early joint mobilisation. We report our experience in the daily management of these lesions. The fractures are evaluated considering fracture type, fracture reduction criteria, adequacy of reduction criteria and overall fracture stability. The best treatment option must be decided in accordance to the type of fracture, the extent of metaphyseal comminution, the quality of the bone and the medical condition of the patient
Do atmospheric aerosols form glasses?
No full textZobrist B, Marcolli C, Pedernera DA, Koop T. Do atmospheric aerosols form glasses? ATMOSPHERIC CHEMISTRY AND PHYSICS. 2008;8(17):5221-5244.A new process is presented by which water soluble organics might influence ice nucleation, ice growth, chemical reactions and water uptake of aerosols in the upper troposphere: the formation of glassy aerosol particles. Glasses are disordered amorphous (non-crystalline) solids that form when a liquid is cooled without crystallization until the viscosity increases exponentially and molecular diffusion practically ceases. The glass transition temperatures, Tg, homogeneous ice nucleation temperatures, Thom, and ice melting temperatures, Tm, of various aqueous inorganic, organic and multi-component solutions are investigated with a differential scanning calorimeter. The investigated solutes are: various polyols, glucose, raffinose, levoglucosan, an aromatic compound, sulfuric acid, ammonium bisulfate and mixtures of dicarboxylic acids (M5), of dicarboxylic acids and ammonium sulfate (M5AS), of two polyols, of glucose and ammonium nitrate, and of raffinose and M5AS. The results indicate that aqueous solutions of the investigated inorganic solutes show Tg values that are too low to be of atmospheric importance. In contrast, aqueous organic and multi-component solutions readily form glasses at low but atmospherically relevant temperatures (≤230 K). To apply the laboratory data to the atmospheric situation, the measured phase transition temperatures were transformed from a concentration to a water activity scale by extrapolating water activities determined between 252 K and 313 K to lower temperatures. The obtained state diagrams reveal that the higher the molar mass of the aqueous organic or multi-component solutes, the higher Tg of their respective solutions at a given water activity. To a lesser extent, Tg also depends on the hydrophilicity of the organic solutes. Therefore, aerosol particles containing larger (≳150 g mol−1) and more hydrophobic organic molecules are more likely to form glasses at intermediate to high relative humidities in the upper troposphere. Our results suggest that the water uptake of aerosols, heterogeneous chemical reactions in aerosol particles, as well as ice nucleation and ice crystal growth can be significantly impeded or even completely inhibited in organic-enriched aerosols at upper tropospheric temperatures with implications for cirrus cloud formation and upper tropospheric relative humidity
Oxalic acid as a heterogeneous ice nucleus in the upper troposphere and its indirect aerosol effect
No full textZobrist B, Marcolli C, Koop T, et al. Oxalic acid as a heterogeneous ice nucleus in the upper troposphere and its indirect aerosol effect. ATMOSPHERIC CHEMISTRY AND PHYSICS. 2006;6(10):3115-3129.Heterogeneous ice freezing points of aqueous solutions containing various immersed solid dicarboxylic acids (oxalic, adipic, succinic, phthalic and fumaric) have been measured with a differential scanning calorimeter. The results show that only the dihydrate of oxalic acid (OAD) acts as a heterogeneous ice nucleus, with an increase in freezing temperature between 2 and 5 K depending on solution composition. In several field campaigns, oxalic acid enriched particles have been detected in the upper troposphere with single particle aerosol mass spectrometry. Simulations with a microphysical box model indicate that the presence of OAD may reduce the ice particle number density in cirrus clouds by up to ~50% when compared to exclusively homogeneous cirrus formation without OAD. Using the ECHAM4 climate model we estimate the global net radiative effect caused by this heterogeneous freezing to result in a cooling as high as −0.3 Wm−2
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Fracture of a polyethylene post in a 9-year-old posterior-stabilized knee prosthesis: light microscopy and SEM evaluation
No full textObjective Aim of this study is to evaluate the surface of the TKA polyethylene liner, harvested after the breakage of the post nine years after the implant in a 63 years old female (BMI 39) after an hyperextension trauma.
Methods During the revision we harvested sample of the periprosthetic tissue which was prepared for the light microscopy evaluation. The samples were stained using both haematoxylineosin and Von Kossa. The PE liner was prepared for the Scanning Electron Microscopy.
Results The SEM evaluation revealed two different damage patterns considering the medial part and the lateral aspect of the sample. The medial part presented a fracture line laminated in front and smooth behind and with the tear lines with a medio-lateral and anterior posterior orientation. The lateral part presented a sharp fracture line that ends anteriorly with a laminated tear paralleled to the anterior edge of the polyethylene insert, and which implies that this area could be the terminal failure area of the fractured post. The medial part of the fracture edge appears to be smooth and with a different orientation of the fracture lines.
Conclusions These features could be explained with a ‘‘two stage’’ rupture of the polyethylene post. This could have been caused by a non-optimal ligamentous balance that weakened the post, which was finally broken by a postero-anterior stress
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
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