Finite difference methods for the solution of unsteady potential flows

Various problems which are confronted in the development of an unsteady finite difference potential code are reviewed mainly in the context of what is done for a typical small disturbance and full potential method. The issues discussed include choice of equations, linearization and conservation, differencing schemes, and algorithm development. A number of applications, including unsteady three dimensional rotor calculations, are demonstrated

Coupled thrust and vorticity dynamics during VRS

The focus is on the vortex ring state (VRS) observed at rapid descent rates. At VRS, the helical vortex filaments coming off the blades amalgamate around the rotor disk forming a vortex ring, which periodically detaches into the wake, causing extreme oscillations in thrust, with periods on the order of several tens of rotor revolutions. We discuss here the phase relation between the thrust cycle and vorticity distribution at the rotor disk. Maxima of the VRS thrust oscilla- tions correlate well with the maxima of circulation, enstrophy, and minima of enstrophy dispersion radius observed in the vicinity of the rotor disk

Experimental and analytical studies of a model helicopter rotor in hover

A benchmark test to aid the development of various rotor performance codes was conducted. Simultaneous blade pressure measurements and tip vortex surveys were made for a wide range of tip Mach numbers including the transonic flow regime. The measured tip vortex strength and geometry permit effective blade loading predictions when used as input to a prescribed wake lifting surface code. It is also shown that with proper inflow and boundary layer modeling, the supercritical flow regime can be accurately predicted

Manual therapy of the mandibular accessory ligaments for the management of temporomandibular joint disorders

Temporomandibular joint disorders are characterized by chronic or acute musculoskeletal or myofascial pain with dysfunction of the masticatory system. Treatment modalities include occlusal splints, patient education, activity modification, muscle and joint exercises, myofascial therapy, acupuncture, and manipulative therapy. In the physiology of the temporomandibular joint, accessory ligaments limit the movement of the mandible. A thorough knowledge of the anatomy of accessory ligaments is necessary for good clinical management of temporomandibular joint disorders. Although general principles regarding the anatomy of the ligaments are relatively clear, very little substantiated information on the dimension, orientation, and function of the ligaments has been published, to the authors' knowledge. The authors review the literature concerning the accessory ligaments of the temporomandibular joint and describe treatment options, including manual techniques for mobilizing the accessory ligaments

Genetics and genomics of BNCT among basics and perspectives

The Boron neutron capture therapy (BNCT) bases its therapeutic action on the selective ability to induce DNA damage of tumor cells with the aim to cause their death by apoptosis or necrosis, preserving as much as possible the normal cells. The genetic variability is an evolutionary mechanism of species survival and improvement according to which diversity in genetic configurations exists among individuals of a population, revealed also in different tolerance to insults and reparative ability of DNA damage induced by physical and chemical agents. A tumor, due to its intrinsic genomic instability, acquires the mutator phenotype and may, during the cell duplications, generate in the same individual neoplastic cells with different mutations which, by clonal selection and expansion, may change some characteristics of the tumor, for example, the aggressiveness and the over-capability to repair DNA breaks to withstand therapies DNA damage-based, such as BNCT. It follows that we must also take account of genetic / genomic parameters of every patient in order to give greater success to BNCT. It would be desirable to act on at least two fronts. 1- Improve boric carriers to give less systemic toxicity (Imperio et al., 2017), greater specificity to the delivery (Wang et al., 2017) and avoid that even a few genomic insult can trigger oncogenic mutations in normal cells, especially in subjects with a risk-genotype(s). 2- Associate genetic studies to determine the preventive patients genotype for some key-genes, the so called \u201dgenome guardians\u201d as TP53 (Seki et al., 2015), BRCA, P16, etc and add this genetic data for an evaluation of the risk / benefit of BNCT cycles. In fact, a patient with a constitutionally heterozygous genotype for some of these key-genes has certainly more risk to have greater genomic instability, BNCT-induced, in normal cells and to generate other secondary tumors. It would also be necessary, when logistically possible, to have serial data from tumor biopsies taken with cyclical time, to detect the genetic / genomic evolution of the tumor, in terms of silencing of certain genes involved in the DNA repair capability. Two recent in vitro studies, in fact, show that deficient cells for gene for DNA ligase IV (LIG4 - / -) are much more sensitive to the effects of BNCT of other proficient cells for this gene (Kondo et al., 2016) and that, on the other hand, may exist apparently healthy subjects, carriers of mutations for LIG4 but totally asymptomatic for cancer or related syndromes (Felgentreff et al., 2016). The first study opens hopeful scenarios in terms of efficacy of BNCT to cancer cells while the second raises the possibility that predict cycles of BNCT on subjects which are constitutionally and asymptomatically carriers of LIG4 mutations can expose them to develop secondary tumors in tissue districts unrelated to the primary tumor. In conclusion today it is necessary to apply also to the BNCT the principles of Pharmacogenetics and Pharmacogenomics that now are spreading in oncology therapy thanks to the massive DNA sequencing techniques. These sciences personalize treatment strategies with the help of genetics and genomics to maximize their curative effects and minimize those unpleasant

Full-potential modeling of blade-vortex interactions

A comparison is made of four different models for predicting the unsteady loading induced by a vortex passing close to an airfoil. (1) The first model approximates the vortex effect as a change in the airfoil angle of attack. (2) The second model is related to the first but, instead of imposing only a constant velocity on the airfoil, the distributed effect of the vortex is computed and used. This is analogous to a lifting surface method. (3) The third model is to specify a branch cut discontinuity in the potential field. The vortex is modeled as a jump in potential across the branch cut, the edge of which represents the center of the vortex. (4) The fourth method models the vortex expressing the potential as the sum of a known potential due to the vortex and an unknown perturbation due to the airfoil. The purpose of the current study is to investigate the four vortex models described above and to determine their relative merits and suitability for use in large three-dimensional codes

The development of CFD methods for rotor applications

The optimum design of the advancing helicopter rotor for high-speed forward flight always involves a tradeoff between transonic and stall limitations. However, the preoccupation of the rotor industry was primarily concerned with stall until well into the 1970s. This emphasis on stall resulted from the prevalent use of low-solidity rotors with rather outdated airfoil sections. The use of cambered airfoil sections and higher-solidity rotors substantially reduced stall and revealed the advancing transonic flow to be a more persistent limitation to high-speed rotor performance. Work in this area was spurred not only by operational necessity but also by the development of a tool for the prediction of these flows (the method of computational fluid dynamics). The development of computational fluid dynamics for these rotor problems was a major Army and NASA achievement. This work is now being extended to other rotor flow problems. The developments are outlined

The histone deacetylase inhibitor JAHA down-regulates pERK and global DNA methylation in MDA-MB231 breast cancer cells

The histone deacetylase inhibitor N1-(ferrocenyl)-N8-hydroxyoctanediamide (JAHA) down-regulates extracellular-signal-regulated kinase (ERK) and its activated form in triple-negative MDA-MB231 breast cancer cells after 18 h and up to 30 h of treatment, and to a lesser extent AKT and phospho-AKT after 30 h and up to 48 h of treatment. Also, DNA methyltransferase 1 (DNMT1), 3b and, to a lesser extent, 3a, downstream ERK targets, were down-regulated already at 18 h with an increase up to 48 h of exposure. Methylation-sensitive restriction arbitrarily-primed (MeSAP) polymerase chain reaction (PCR) analysis confirmed the ability of JAHA to induce genome-wide DNA hypomethylation at 48 h of exposure. Collective data suggest that JAHA, by down-regulating phospho-ERK, impairs DNMT1 and 3b expression and ultimately DNA methylation extent, which may be related to its cytotoxic effect on this cancer cytotype

A conservative implicit finite difference algorithm for the unsteady transonic full potential equation

An implicit finite difference procedure is developed to solve the unsteady full potential equation in conservation law form. Computational efficiency is maintained by use of approximate factorization techniques. The numerical algorithm is first order in time and second order in space. A circulation model and difference equations are developed for lifting airfoils in unsteady flow; however, thin airfoil body boundary conditions have been used with stretching functions to simplify the development of the numerical algorithm

La conservazione della biodiversità dei boschi nativi: un investimento in “salute genetica”

Tutti i viventi sono fenotipicamente diversi fra loro e mostrano, anche all’interno della stessa specie, variabilità fenotipica che li rende peculiari e unici. Soltanto in uno scenario di grande diversità, infatti, è possibile distinguere un individuo da un altro e di conseguenza può essere asserito che l’unicità è la funzione della diversità, tanto per gli animali che per i vegetali. Queste differenze fenotipiche sottintendono, com’è ovvio, una differenza genotipica, una variabilità genetica che è la base della biodiversità all’interno di uno stesso genere. Prendendo in considerazione il genere Prosopis, ad esempio, un albero giudicato patrimonio boschivo in Argentina, possiamo asserire che sono presenti almeno 14 specie di questo genere che rappresentano un patrimonio notevole in termini di biodiversità da salvaguardare. La variabilità genetica è sostenuta dalla variabilità di sequenze del DNA degli individui la quale a sua volta è innescata da mutazioni genetiche appositamente selezionate, in termini di fitness, dall’ambiente in cui vive il soggetto. Individui diversi hanno diverse reazioni per stessi stimoli ambientali e quindi è ormai ampiamente riconosciuto che la biodiversità è il principale meccanismo usato dall’evoluzione per diversificare i viventi sul pianeta ed anche per dare agli individui di una stessa specie diverse possibilità di sopravvivere in caso di forti pressioni negative ambientali. La biodiversità è quindi una misura quantitativa della “salute genetica” di una specie, infatti, quanto più diversità essa ha al suo interno, tante più chances di sopravvivenza avrà in caso di ambiente ostile. Oggi è possibile rivelare questa biodiversità estraendo il DNA dell’individuo, amplificando specifiche sequenze (microsatelliti) e valutando le diversità alleliche per questi specifici loci. Per il genere Prosopis la ricerca è più avviata essendo stati pubblicati ad oggi 12 sequenze microsatellitari con cui misurare la specifica biodiversità; è quindi possibile fornire per questa specie, più che per altre del patrimonio boschivo argentino, l’informazione dello stato di salute genetica della specie per poter avviare, eventualmente, con congruo anticipo, protocolli di salvaguardia della biodiversità. Quando, infatti, una specie comincia a perdere biodiversità, per esempio per opera di attività antropiche dirette o indirette, inevitabilmente, generazione dopo generazione, sarà composta da individui con poche differenze genomiche e fenotipiche: questo riduce di molto la fitness degli individui e della specie in questione. Volendo schematizzare le conseguenze che ne scaturiranno, può essere detto che un’unica eventuale ostilità ambientale potrebbe estinguere la specie perché cagiona gli stessi fatali danni ad individui uguali che quindi non potranno che mostrare uguali debolezze. Conservare la biodiversità di qualunque vivente del pianeta è quindi un dovere biologico che tutti dobbiamo sentire come prioritario, specialmente se le specie in questioni sono alberi da bosco poiché questi rappresentano una garanzia di vita per moltissime altre specie, uomo incluso