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The way Leibniz applied his philosophy to mathematics has been the subject of longstanding debates. A key piece of evidence is his letter to Masson on bodies. We offer an interpretation of this often misunderstood text, dealing with the status of infinite divisibility in nature , rather than in mathematics. In line with this distinction, we offer a reading of the fictionality of infinitesimals. The letter has been claimed to support a reading of infinitesimals according to which they are logical fictions, contradictory in their definition, and thus absolutely impossible. The advocates of such a reading have lumped infinitesimals with infinite wholes, which are rejected by Leibniz as contradicting the part–whole principle. Far from supporting this reading, the letter is arguably consistent with the view that infinitesimals, as inassignable quantities, are mentis fictiones , i.e., (well-founded) fictions usable in mathematics, but possibly contrary to the Leibnizian principle of the harmony of things and not necessarily idealizing anything in rerum natura. Unlike infinite wholes, infinitesimals—as well as imaginary roots and other well-founded fictions—may involve accidental (as opposed to absolute) impossibilities, in accordance with the Leibnizian theories of knowledge and modality. [ABSTRACT FROM AUTHOR]

Depuis 2012, les patients insuffisants rénaux chroniques de Nouvelle-Calédonie peuvent être inscrits sur une liste d'attente locale, et la transplantation rénale est réalisée en Australie. Ce programme a permis de diminuer le temps passé hors territoire pour une greffe rénale et de réduire la charge économique d'une greffe rénale pour la Nouvelle-Calédonie. Nous avons réalisé un état des lieux afin d'avoir un regard objectif sur la situation actuelle. L'objectif principal était de décrire l'accès à la liste d'attente pour les patients en dialyse péritonéale, et dans un second temps, de comparer les patients ayant un parcours à l'accès à la greffe conforme aux recommandations de la Haute Autorité de santé versus non conforme. Tous les patients en dialyse péritonéale au 31 juillet 2018 ont été inclus. Un questionnaire standardisé a été rempli par deux néphrologues, en s'appuyant sur le dossier médical informatisé et partagé du patient. Le parcours d'accès à la liste d'attente de greffe était considéré conforme si le patient était inscrit sur liste d'attente ou s'il avait une contre-indication à la greffe, ou encore si un bilan pré-transplantation datait de moins de 6 mois. Le parcours était considéré non conforme si le patient avait commencé un bilan depuis plus de 6 mois ou n'avait pas commencé son bilan. Au total, 61 patients de Nouvelle-Calédonie et Wallis et Futuna suivis en dialyse péritonéale ont été inclus. Ils étaient âgés en moyenne de 62 ans. La durée moyenne depuis la prise en charge de l'insuffisance rénale chronique était de 6,7 ans et depuis la mise en dialyse de 2,0 ans. Parmi eux, 11 (18 %) étaient inscrits sur liste d'attente, 26 (43 %) avaient au moins un motif contre-indiquant la greffe rénale, 3 (5 %) avaient commencé un bilan depuis moins de 6 mois et 21 (34 %) avaient un bilan qui durait depuis plus de 6 mois ou n'avaient pas commencé leur bilan. Parmi ces 21 patients avec un parcours non conforme, les 3 raisons le plus fréquemment identifiées étaient une programmation du bilan défectueuse (67 % ; n = 14), un éloignement géographique (48 % ; n = 10) et un événement de santé intercurrent (29 % ; n = 6). Parmi les patients résidant dans le Grand Nouméa, 74 % avaient un bilan conforme contre 44 % pour les patients résidant hors le Grand Nouméa (p = 0,058). Près d'un patient sur deux non inscrit sur liste d'attente n'a pas eu d'information sur la greffe rénale ou l'information n'a pas été tracée dans le dossier médical informatisé. Cette étude a mis en évidence 2 facteurs principaux d'une évaluation non conforme à la transplantation rénale : habiter en dehors du Grand Nouméa et une programmation de bilan défectueuse. Il apparaît également un manque d'information au patient. Ces facteurs de risque d'inscription tardive et de non-inscription sont à prendre en compte par les équipes soignantes. Cet état des lieux permettra d'avoir un point de référence pour évaluer l'impact des actions d'amélioration d'accès à la transplantation rénale déployées en Nouvelle-Calédonie. Since 2012, a deceased donor kidney transplant program exists for dialysis patients living in New-Caledonia in collaboration with Royal Prince Alfred Hospital in Sydney, Australia. This program has reduced the time spent out-of-territory for a renal transplantation and has reduced the economic burden of end stage renal disease in New-Caledonia. We have realised a photography of kidney transplants evaluation for patients in peritoneal dialysis in New-Caledonia and Wallis and Futuna. The first aim was to describe access to kidney transplants evaluation for dialysis patients. A second aim was to compare patients with a conformed kidney transplant evaluation and patients without transplant evaluation with no obvious reasons identified. All patients in peritoneal dialysis in New-Caledonia and Wallis and Futuna at the 2018, 31st july were included. A standardised form was filled by two nephrologists. The computerised shared medical record was used to collect information. A kidney transplant evaluation was adequate for patients registered on transplant waiting list, patients with medical contraindications identified or patients with evaluation exams begun less than 6 months. In total, 61 patients were included. The average age was 62 years old. The chronic kidney disease care average time was 6.7 years and the dialysis average time was 2.0 years. Among them, 11 (18 %) were registered on the waiting list, 26 (43 %) had at least one kidney transplant medical contraindication, 3 (5 %) had begun transplant exam since less than 6 months and 21 (34 %) had no transplant exam begun or transplant exam begun since more than 6 months without medical contraindication identified. Among those 21 patients, the three most common reasons were a faulty programming transplant exam (67 %; n = 14), a remote living place (48 %; n = 10) and an intercurrent health event (29 %; n = 6). Among patients living in Noumea and suburbs, 74 % had a conformed transplant evaluation against 44 % in patients living outside Noumea and suburbs (P = 0.058). Nearly one in two patients not on the waiting list had have no information about kidney graft or the information was not recorded in the medical record. This study showed two main factors of a non-conformed transplantation evaluation: living outside Noumea and suburbs and a non-efficient planning of pre-transplant assessment exams. There is also a lack of information to the patient. These risk factors for late registration and non-registration must be considered by the healthcare teams. This study will provide a point of reference to assess the impact of actions to improve access to renal transplantation deployed in New-Caledonia. [ABSTRACT FROM AUTHOR]

The problem of the rectification of curves and the calculation (for which we shall adopt the more geometric term "flattening") of the surface of a rotating solid generated by a curve, once the rotation axis has been fixed, were treated by John Wallis in two short inter-related tracts on cycloids and cissoids in 1659. In this work, we focus on the problem of the rectification of the parabola, an ancient problem reproposed in the 17th century, and on the solution obtained by Wallis using particular series that reflect the mechanical method of Archimedes, even if this is not immediately apparent to the reader. In presenting Wallis's speech, we use the language closest to us and make explicit all the calculations not performed by the author, favoring an understanding of the part of his writing dedicated to the rectification of the parabola. [ABSTRACT FROM AUTHOR]

This article proposes a possible path devoted to upper secondary school and early university students, as well as training teachers, with the aim to build a conscious approach to the learning/teaching of the conics, which uses, for an educational purpose, the close relationship between conics as loci of points of a plane and conics as sections of a cone. In this path, we will refer to some elements taken from the history of mathematics relating to a particular conic: the parabola. These elements could help students to discover and realize the transition from a parabola considered as a curve in a plane to the same parabola considered on a cone of which it is a section, as well as the inverse passage, and to grasp the profound link between two presentations of the same geometric object. Both steps will be carried out through constructions made with the use of the GeoGebra dynamic geometry software. In addition, it will be highlighted how the construction of conics by points has allowed the creation of lenses and mirrors, which represents a practical application of geometry very relevant to physics and astronomy. Such a practical approach could help students to overcome the difficulty in understanding conics by making the argument less abstract. Moreover, this path could build up an environment in which teachers and students could explore some semiotic registers and their changes, through which Mathematics expresses itself. In the final part, an educational experiment of the path that was proposed will be shown to the students of the Master's degree course of "mathematics education" at the Department of Mathematics and Computer Science of the University of Calabria. The results of this experiment are described in detail and seem to confirm that the twofold view of the parabola as a section of a cone and as locus of points of a plane helps the students in understanding its meaning in both theoretical and applicative fields. [ABSTRACT FROM AUTHOR]

The problem of the rectification of curves and the calculation (for which we shall adopt the more geometric term “flattening”) of the surface of a rotating solid generated by a curve, once the rotation axis has been fixed, were treated by John Wallis in two short inter-related tracts on cycloids and cissoids in 1659. In this work, we focus on the problem of the rectification of the parabola, an ancient problem reproposed in the 17th century, and on the solution obtained by Wallis using particular series that reflect the mechanical method of Archimedes, even if this is not immediately apparent to the reader. In presenting Wallis’s speech, we use the language closest to us and make explicit all the calculations not performed by the author, favoring an understanding of the part of his writing dedicated to the rectification of the parabola.

A set of six publications have introduced, commented, criticized and defended Amir Alexander’s book on infinitesimals published in 2014. The aim of the following article is to bring the various arguments together. [ABSTRACT FROM AUTHOR]

Emulating the Greek geometers, Newton used synthetic demonstration to present the groundbreaking arguments of the Principia. This paper argues that we can better understand Newton's reasons for using geometry by considering John Wallis's interpretation of synthetic demonstration. Wallis condemned demonstration for failing to explain the mathematical truths it presented. He opposed to it a presentation that combined symbolic analysis with a documented account of discovery. In preferring symbols, Wallis was motivated both by the nascent tradition of symbolic analysis and by contemporary interest in artificial languages. Newton maintained Wallis's characterization of Greek demonstration as adapted to common understanding rather than as strictly elucidating, but he inverted the values Wallis associated with synthesis and analysis. In Newton's new account, synthetic demonstration was preferable precisely because it could address inexpert readers without exposing them to the complications of symbols-based analysis. Newton advanced his arguments on behalf of geometry through portraits of ancient mathematicians: Archimedes and Pythagoras. [ABSTRACT FROM AUTHOR]

In his posthumously published work Chartham News (1669), the antiquary William Somner tentatively sought to link the discovery of fossilized remains near Canterbury to the prehistoric existence of an isthmus connecting Britain and France, before calling on natural philosophers to pursue his explanation further. This call was eventually heeded by the Oxford mathematician John Wallis, but only after more than thirty years had elapsed. The arrival in England of a catalogue of questions concerning the geology of the Channel led to the republication of Chartham News in the Philosophical Transactions, prompting Wallis to develop a physical explanation based on his intimate knowledge of the Kent coastline. Unbeknown to Wallis at the time, that catalogue had been sent by G. W. Leibniz, who had in turn received it from G. D. Schmidt, the former Resident of Brunswick-Lüneburg in Sweden. Wallis's explanation, based on the principle of establishing physical causes both for the rupturing of the isthmus and for the origin of fossils, placed him in a camp opposed by Newtonian authors such as John Harris at a time when the priority dispute over the discovery of the calculus led to the severing of his ties with the German mathematician and philosopher Leibniz. [ABSTRACT FROM AUTHOR]

In this article we decided to begin with the 12th Century because this century witnessed huge mathematical interest in Western Europe stimulated by Arabic original books as well as translated ones being translated into Latin (which became the venue of intellectual and scientific domains in Western Europe and remained in this academic function until the 18th century) at Spain translation centers. Despite the long war between the kingdoms of England and France from 1337 to 1453 resulting in famine and plague in the 14th and the first half of the 15th century, the year 1450 witnessed the advent of the printing press which had an enormous impact on printing arithmetic books for the purpose of teaching business people computational methods for their commercial needs. A more detailed treatment is done on later centuries. [ABSTRACT FROM AUTHOR]

An asymptotic approximation of Wallis' sequence m ↦ W m : = ∏ k = 1 m 4 k 2 4 k 2 − 1 is presented as W m = m π 2 m + 1 exp ⁡ ( 2 σ q ( m ) ) ⋅ exp ⁡ ( r q ( m ) ) , where σ q ( x ) : = ∑ i = 1 ⌊ q / 2 ⌋ ( 1 − 4 − i ) B 2 i i ( 2 i − 1 ) ⋅ x 2 i − 1 ( B k are the Bernoulli coefficients ) , and where | r q ( m ) | < r q ⁎ ( m ) : = 2 π ( q − 2 ) ! 3 ( 2 m π ) q − 1 , for any integers m ≥ 1 and q ≥ 2 . Parameters m and q control the error factor exp ⁡ ( r q ( m ) ) . [ABSTRACT FROM AUTHOR]

As Boeing 737-800 Flight simulator get more and more demanding in terms of rendering time and authenticity. In order to reduce the amount of image data, we use the large region low-resolution remote sensing image mosaic with small region high-resolution remote sensing image. Meanwhile, for the color imbalances between images, we propose the global Wallis transform method based on HSI color space, So that the color is consistent among the images. Finally, we present a novel texture technique to achieve real-time performance. The experiment shows that the method can make sure the texture fit the requirement of Boeing 737-800 Flight Simulator.

Review of The Tao of Liberation: Exploring the Ecology of Transformation, by Mark Hathaway and Leonardo Boff

We evaluate the clinical effects and radiological findings of the Wallis interspinous device (Zimmer, Warsaw, IN, USA) for the treatment of multi-segmental lumbar degenerative disease after a minimum 5 year follow-up period. A total of 26 adult patients underwent a primary discectomy followed by fixation of the segment with the Wallis interspinous device between December 2007 and August 2008. Twelve men and 14 women with an age range of 43 to 56 years (average: 47.6) were included. The visual analogue scale (VAS) for low back and leg pain, Oswestry Disability Index (ODI), foraminal height (FH), anterior disc height (aDH) and posterior disc height (pDH), range of motion (ROM) and Pfirrmann grades were obtained and compared before and after surgery. The VAS and ODI significantly decreased postoperatively ( p < 0.05). The postoperative FH and pDH values increased significantly compared with the preoperative levels ( p < 0.01) and the increase in the FH and pDH values remained statistically significant during the follow-up period. There were no statistically significant changes in the aDH values before and after surgery ( p > 0.05). Also, there were no statistically significant changes in the ROM and Pfirrmann grade at the instrumented level and at the cephalad-adjacent segment ( p > 0.05). In our study, no patient underwent further surgery because of a re-prolapse or progression of index level degeneration or adjacent segment disease. The Wallis interspinous device was a useful alternative for treating multi-segmental lumbar degenerative disease and it offered a significant minimum 5 year symptom control. [ABSTRACT FROM AUTHOR]

Background: Dynamic interspinous stabilization devices generally provide satisfactory results, but can result in recurrent lumbar disc herniation, spinous process fracture, or bone resorption of the spinous process. The purpose of this study was to investigate if the Wallis dynamic stabilization device is associated with bone resorption. Methods: Patients who underwent single-segment posterior lumbar decompression and implantation of a Wallis dynamic interspinous stabilization device at the L4/5 level between January 1, 2009 and October 1, 2011 were included. Bone resorption rate, Oswestry Disability Index (ODI), Japanese Orthopedic Association (JOA) score, and visual analogue scale (VAS) pain score were measured. Patient baseline and 1-year follow-up data were collected and analyzed. The bone resorption rate of the L4 and L5 spinous processes was calculated. Results: Twenty four males and 20 females with a mean age of 42.7 ± 14.7 years were included. Twenty nine patients had significant bone resorption (bone resorption rate > 20%) and 15 had no bone resorption (bone resorption rate ≤ 20%) at 1 year after surgery. Lumbar lordosis ≥ 50° was associated with a lower bone resorption than lumbar lordosis < 50° and increasing BMI was associated with increased bone resorption. There were no significant differences between the bone resorption and no bone resorption groups in the improvement rate of VAS pain score, ODI, and JOA score at 1 year after surgery. Conclusions: Significant bone resorption occurs within 1 year after implantation of the Wallis device in more than 50% of patients. However, it does not affect short-term functional results. [ABSTRACT FROM AUTHOR]

Vieta's product for 2/π has factors that are nested radicals. The Wallis product for 2/π has factors that are rational numbers. Brouncker gave continued fractions for 4/π. By summarizing some recently published results in this expository paper, we show that these seemingly unrelated results are connected. We give a general formula in which the products of Vieta and Wallis are special cases. We give another general formula of which the results of Brouncker and Wallis are special cases. Both formulas allow us to 'morph' from one result to the other. [ABSTRACT FROM AUTHOR]

Abstract: John Wallis, Savilian professor of geometry at Oxford from 1649 to 1703, engaged in a number of disputes with French mathematicians: with Fermat (in 1657–1658), with Pascal (in 1658–1659), with Dulaurens (in 1667–1668), and against Descartes (in the early 1670s). This paper examines not only the mathematical content of the arguments but also Wallis’s various strategies of response. Wallis’s opinion of French mathematicians became increasingly bitter, but at the same time he was able to use the confrontations to promote his own reputation. [Copyright &y& Elsevier]

Treatment of chronic low back pain due to degenerative lumbar spine conditions often involves fusion of the symptomatic level. A known risk of this procedure is accelerated adjacent level degeneration. Motion preservation devices have been designed to provide stabilization to the symptomatic motion segment while preserving some physiologic motion. The aim of this study was to compare the changes in relative range of motion caused as a result of application of two non-fusion, dynamic stabilization devices: the Universal Clamp (UC) and the Wallis device. Nine fresh, frozen human lumbar spines (L1-Sacrum) were tested in flexion-extension, lateral bending, and axial rotation with a custom spine simulator. Specimens were tested in four conditions: (1) intact, (2) the Universal Clamp implanted at L3-4 (UC), (3) the UC with a transverse rod added (UCTR), and (4) the Wallis device implanted at L3-4. Total range of motion at 7.5 N-m was determined for each device and compared to intact condition. The UC device (with or without a transverse rod) restricted motion in all planes more than the Wallis. The greatest restriction was observed in flexion. The neutral position of the L3-4 motion segment shifted toward extension with the UC and UCTR. Motion at the adjacent levels remained similar to that observed in the intact spine for all three constructs. These results suggest that the UC device may be an appropriate dynamic stabilization device for degenerative lumbar disorders. [ABSTRACT FROM AUTHOR]

Marine protected areas (MPAs) have been highlighted as a means toward effective conservation of coral reefs. New strategies are required to more effectively select MPA locations and increase the pace of their implementation. Many criteria exist to design MPA networks, but generally, it is recommended that networks conserve a diversity of species selected for, among other attributes, their representativeness, rarity, or endemicity. Because knowledge of species’ spatial distribution remains scarce, efficient surrogates are urgently needed. We used five different levels of habitat maps and six spatial scales of analysis to identify under which circumstances habitat data used to design MPA networks for Wallis Island provided better representation of species than random choice alone. Protected-area site selections were derived from a rarity–complementarity algorithm. Habitat surrogacy was tested for commercial fish species, all fish species, commercially harvested invertebrates, corals, and algae species. Efficiency of habitat surrogacy varied by species group, type of habitat map, and spatial scale of analysis. Maps with the highest habitat thematic complexity provided better surrogates than simpler maps and were more robust to changes in spatial scales. Surrogates were most efficient for commercial fishes, corals, and algae but not for commercial invertebrates. Conversely, other measurements of species-habitat associations, such as richness congruence and composition similarities provided weak results. We provide, in part, a habitat-mapping methodology for designation of MPAs for Pacific Ocean islands that are characterized by habitat zonations similar to Wallis. Given the increasing availability and affordability of space-borne imagery to map habitats, our approach could appreciably facilitate and improve current approaches to coral reef conservation and enhance MPA implementation. [ABSTRACT FROM AUTHOR]

The species diversity of the subgenus Sargassum was reassessed for the southwestern Pacific with special focus on the Solomon Islands, Vanuatu, Fiji, and Wallis. Five taxa were recognized on the basis of morphological characters and corroborated by DNA analyses of the nuclear internal transcribed spacer 2 ( ITS-2), chloroplastic partial rbcLS-operon, and mitochondrial cox3. Based on the study of diagnoses and type specimens, four taxa were identified to S. polyphyllum J. Agardh, S. polycystum C. Agardh, S. aquifolium (Turner) C. Agardh, and S. ilicifolium (Turner) C. Agardh, while one taxon remained unidentified. We present a key for identification that includes detailed descriptions of the species and illustrations of their morphological variability. In light of our findings, we propose to consider several new synonymies for S. aquifolium, S. ilicifolium, S. polycystum, and S. polyphyllum. We also include a review of Sargassum floras from Samoa, Tonga, and Nauru and discuss species distribution in the southwest and central Pacific. Finally, DNA phylogenies pointed to the polyphyly of section Acanthocarpicae and underlined the need for a new section in which to place S. polycystum, S. herporhizum Setch. et N. L. Gardner, and S. stolonifolium Phang et T. Yoshida. The new section Polycystae Mattio et Payri is described to fit species of the subgenus Sargassum with stolon-like branches. [ABSTRACT FROM AUTHOR]

Interspinous implants (ISP) represent a contemporary non-fusion surgical option in the treatment of lumbar segment disease. Several devices have been developed within the last two decades and have been variously supported by investigations into their clinical and biomechanical efficacy. Spinal stenosis and facet arthropathy are reported as the primary clinical indications for their use, with degenerative disc disease and segmental instability recently extending their application. The principle common to all interspinous systems is an induced distraction of the interspinous space, resulting in reduced approximation of pain-sensitive and space-occupying tissue. Collectively, these devices are considered to prevent adjacent segment overload by restoring physiologic load transmission. This review article summarizes existing published literature, describes four different interspinous implants — the DIAM, Wallis, X-Stop and Coflex systems, and outlines clinical trials in progress. The design and surgical technique characteristics, mechanism of action, and clinical indications for interspinous implants are reviewed. Recommendations for future research of interspinous implants in the treatment of lumbar segment disease are made. [ABSTRACT FROM AUTHOR]

Delayed complications following lumbar spine fusion may occur amongst which is adjacent segment degeneration (ASD). Although interspinous implants have been successfully used in spinal stenosis to authors’ knowledge such implants have not been previously used to reduce ASD in instrumented lumbar fusion. This prospective controlled study was designed to investigate if the implantation of an interspinous implant cephalad to short lumbar and lumbosacral instrumented fusion could eliminate the incidence of ASD and subsequently the related re-operation rate. Groups W and C enrolled initially each 25 consecutive selected patients. Group W included patients, who received the Wallis interspinous implant in the unfused vertebral segment cephalad to instrumentation and the group C selected age-, diagnosis-, level-, and instrumentation-matched to W group patients without interspinous implant (controls). The inclusion criterion for Wallis implantation was UCLA arthritic grade UCLA grade II in the adjacent two segments cephalad to instrumentation. All patients suffered from symptomatic spinal stenosis and underwent decompression and 2–4 levels stabilization with rigid pedicle screw fixation and posterolateral fusion by a single surgeon. Lumbar lordosis, disc height (DH), segmental range of motion (ROM), and percent olisthesis in the adjacent two cephalad to instrumentation segments were measured preoperatively, and postoperatively until the final evaluation. VAS, SF-36, and Oswestry Disability Index (ODI) were used. One patient of group W developed pseudarthrosis: two patients of group C deep infection and one patient of group C ASD in the segment below instrumentation and were excluded from the final evaluation. Thus, 24 patients of group W and 21 in group C aged 65+ 13 and 64+ 11 years, respectively were included in the final analysis. The follow-up averaged 60 ± 6 months. The instrumented levels averaged 2.5 + 1 vertebra for both groups. All 45 spines showed radiological fusion 8–12 months postoperatively. Lumbar lordosis did not change postoperatively. Postoperatively at the first cephalad adjacent segment: DH increased in the group W ( P = 0.042); ROM significantly increased only in group C (ANOVA, P < 0.02); olisthesis decreased both in flexion ( P = 0.0024) and extension ( P = 0.012) in group W. The degeneration or deterioration of already existed ASD in the two cephalad segments was shown in 1 (4.1%) and 6 (28.6%) spines in W and C groups, respectively. Physical function (SF-36) and ODI improved postoperatively ( P < 0.001), but in favour of the patients of group W ( P < 0.05) at the final evaluation. Symptomatic ASD required surgical intervention was in 3 (14%) patients of group C and none in group W. ASD remains a significant problem and accounts for a big portion of revision surgery following instrumented lumbar fusion. In this series, the Wallis interspinous implant changed the natural history of ASD and saved the two cephalad adjacent unfused vertebra from fusion, while it lowered the radiographic ASD incidence until to 5 years postoperatively. Longer prospective randomized studies are necessary to prove the beneficial effect of the interspinous implant cephalad and caudal to instrumented fusion. We recommend Wallis device for UCLA degeneration I and II. [ABSTRACT FROM AUTHOR]

Undercutting decompression is a common surgical procedure for the therapy of lumbar spinal canal stenosis. Segmental instability, due to segmental degeneration or iatrogenic decompression is a typical problem that is clinically addressed by fusion, or more recently by semi-rigid stabilization devices. The objective of this experimental biomechanical study was to investigate the influence of spinal decompression alone, as well as in conjunction with two semi-rigid stabilizing implants (Wallis, Dynesys®) on the range of motion (ROM) of lumbar spine segments. A total of 21 fresh-frozen human lumbar spine motion segments were obtained. Range of motion and neutral zone (NZ) were measured in flexion-extension (FE), lateral bending (LAT) and axial rotation (ROT) for each motion segment under four conditions: (1) with all stabilizing structures intact (PHY), (2) after bilateral undercutting decompression (UDC), (3) after additional implantation of Wallis (UDC-W) and (4) after removal of Wallis and subsequent implantation of Dynesys® (UDC-D). Measurements were performed using a sensor-guided industrial robot in a pure-moment-loading mode. Range of motion was defined as the angle covered between loadings of −5 and +5 Nm during the last of three applied motion cycles. Untreated physiologic segments showed the following mean ROM: FE 6.6°, LAT 7.4°, ROT 3.9°. After decompression, a significant increase of ROM was observed: 26% FE, 6% LAT, 12% ROT. After additional implantation of a semi-rigid device, a decrease in ROM compared to the situation after decompression alone was observed with a reduction of 66 and 75% in FE, 6 and 70% in LAT, and 5 and 22% in ROT being observed for the Wallis and Dynesys®, respectively. When the flexion and extension contribution to ROM was separated, the Wallis implant restricted extension by 69% and flexion by 62%, the Dynesys® by 73 and 75%, respectively. Compared to the intact status, instrumentation following decompression led to a ROM reduction of 58 and 68% in FE, 1 and 68% in LAT, −6 and 13% in ROT, 61 and 65% in extension and 54 and 70% in flexion for Wallis and Dynesys®. The effect of the implants on NZ corresponded to that on ROM. In conclusion, implantation of the Wallis and Dynesys® devices following decompression leads to a restriction of ROM in all motion planes investigated. Flexion–extension is most affected by both implants. The Dynesys® implant leads to an additional strong restriction in lateral bending. Rotation is only mildly affected by both implants. Wallis and Dynesys® restrict not only isolated extension, but also flexion. These biomechanical results support the hypothesis that postoperatively, the semi-rigid implants provide a primary stabilizing function directly. Whether they can improve the clinical outcome must still be verified in prospective clinical investigations. [ABSTRACT FROM AUTHOR]

Posterior lumbar interbody fusion and lumbar interspinous non-fusion technique are common surgical procedures for lumbar degenerative diseases, but the effectiveness and safety of these two techniques are still unclear. We performed this network meta-analysis to evaluate the comparative effectiveness and safety of posterior lumbar interbody fusion and the three commonly used interspinous devices including Coflex, Wallis, and X-stop for lumbar degenerative diseases. Randomized controlled trials and cohort studies comparing among posterior lumbar interbody fusion, Coflex, Wallis, and X-stop for lumbar degenerative diseases were identified using the databases including PubMed, the Cochrane Library, Web of Science, the China National Knowledge Infrastructure, Chinese Science and Technology Periodical Database, and Wanfang data. A network meta-analysis was performed using R 3.4.3 software. 27 studies with 2241 patients were included. The results of network meta-analysis revealed that no significant differences in Oswestry Disability Index, Visual Analogue Scale, Japanese Orthopedic Association Scores, and posterior disc height were found among posterior lumbar interbody fusion group, Coflex, Wallis, or X-stop. However, compared with posterior lumbar interbody fusion, the three interspinous process devices presented with significantly more range of motion in surgical segment, but no significant difference was found among these three interspinous process devices. Node-splitting analysis showed no significant inconsistency in our network meta-analysis. We concluded that compared with posterior lumbar interbody fusion, Coflex, Wallis and X-stop had the same effectiveness in relieving pain, improving quality of life, recovering disc space height and lumbar function, but may lower incidence of adjacent segment degeneration., (Copyright © 2018 Elsevier B.V. All rights reserved.)

This article develops the results of Firth, Duranti and Salmond showing the interactional, cognitive, social and political dimensions of greetings in the Pacific. Some of their more strictly operative and ritual aspects are also considered. Starting from a Polynesian ethnography of linguistic practices and local conceptions of the socio-cosmic world, I present the modalities of action, especially of speech acts (names enunciation) in ceremonial contexts. Greetings have an instituting character based on the act of naming and on the forms of co-presence it recognises and establishes, conferring on the actions their legitimacy and their efficiency. If greetings are part of processes analysed by others in terms of power and politics, another way to look at it shows that it is mostly about defining the type of interactions to come, specifying the co-participants (human beings, ancestors, God), and eventually determining their framework and the extent of their results. Greetings give actions their foundation and efficiency. [ABSTRACT FROM AUTHOR]