The hard life of air bubbles crossing a fluid/fluid interface

We investigate the dynamics of isolated air bubbles crossing the horizontal interface separating two Newtonian immiscible liquids initially at rest by means of experiments and DNS. High-speed video imaging is used to obtain a detailed evolution of the various interfaces involved in the system. The size of the bubbles and the viscosity contrast between the two liquids are varied by more than one and four orders of magnitude, respectively, making it possible to obtain bubble shapes ranging from spherical to toroidal. A variety of flow regimes is observed, including that of small bubbles remaining trapped at the fluid–fluid interface in a film-drainage configuration. In most cases, the bubble succeeds in crossing the interface without being stopped near its undisturbed position and, during a certain period of time, tows a significant column of lower fluid which sometimes exhibits a complex dynamics as it lengthens in the upper fluid. Direct numerical simulations of several selected experimental situations are performed with a code employing a volume-of-fluid type formulation of the incompressible Navier–Stokes equations. Comparisons between experimental and numerical results confirm the reliability of the computational approach in most situations but also points out the need for improvements to capture some subtle but important physical processes, most notably those related to film drainage. Influence of the physical parameters highlighted by experiments and computations, especially that of the density and viscosity contrasts between the two fluids and of the various interfacial tensions, is discussed and analysed in the light of simple models

Homes of the future

K

The impact of scientific evidence and price level of hypertension drug therapies on their market performance – A Europe based analysis

This study aims to investigate how much the market performance of drug therapies is influenced by their scientific evidence and price level. Compared to the seemingly simple objective, performing the analysis in the pharmaceutical industry makes the evaluation very complex. Examining the purchase decision process in the prescription drug market, besides the patient as the final consumer, the prescribing physician has the largest decision potential. In addition, the authors cannot ignore the healthcare system financing the therapy either, not to mention the interlacements of regulations, manufacturer interests, their marketing potential and marketing activities. This complexity makes it impossible to describe the pharmaceutical industry in uniform terms. The literature search also confirms that the mentioned complexity makes it hard to draw unambiguous conclusions. In spite of that –with a positivistic approach- the authors live with the assumption that scientific evidence (better efficacy and safety profile) should be awarded on the market on the aggregate level. It is inevitable to clarify at the very beginning that the authors investigate active pharmaceutical ingredients (APIs) and not brands in the recent study. With all this in mind, their intention is to introduce a novel approach for the evaluation of the relationship between the product characteristics (clinical evidence of APIs) and their market performance. In order to examine the relationship the authors involved APIs that belong to the same indication group, having the same mechanism of action and which have been in the generic competition for years after their patent have expired. As a model they perform the analysis with antihypertensive drug therapies. The authors consider that it is possible to rank the active ingredients of drug therapies on the basis of their efficacy and safety, based on relevant clinical literature. The result of ranking serves as the starting point of the analysis. Unequivocally, the authors do not forget about the additional factors that significantly influence the market performance of APIs, but deliberately do not involve these factors in the recent analysis. These factors are the different reimbursement and funding policies, marketing activity of the manufacturers, country-of-origin effect, the impact of clinical guidelines and clinical literature, and their effect on each other. There is one exception, since the article partially deals with the influence of price level on the market performance. In contrast with the majority of the available literature, this study aims to explore the identifiable patterns by investigating the European pharmaceutical market on system-level

Homes of the Future

L

Nonlinear Model Predictive Control Using Robust Fixed Point Transformation-Based Phenomena for Controlling Tumor Growth

In this paper a novel control strategy is introduced in order to create optimal dosage profiles for individualized cancer treatment. This approach uses Nonlinear Model Predictive Control to construct optimal dosage protocols in conjunction with Robust Fixed Point Transformations which hinders the negative effect of inherent model uncertainties and measurement disturbances. The results are validated by extensive simulation on the proposed control algorithm from which conclusions were drawn

The effect of different forest management types on the survival rate of epixylic and epiphytic bryophytes

This research investigates experimentally the effect of different forest management types on the survival of an epixylic liverwort (Lophocolea heterophylla) and an epiphytic-opportunistic bryophyte (Hypnum cupressiforme). Five different management types were applied in an 80-year-old oak-hornbeam forest: (1) Preparation cutting, (2) Gap cutting, (3) Clear-cutting, (4) Retention tree group (in the clear-cutting) and (5) Control. It was hypothesized, that the epixylic liverwort, which is more sensitive to microclimatic conditions, will show a more drastic response to the treatments than the epiphytic bryophyte. The results showed that the liverwort in the control survived moderately, poorly in the gap and preparation cutting, and became extinct in the clear-cutting and retention tree group. The survival rate of the epiphytic bryophyte showed a slight decline only in the clear-cutting, and it managed to grow larger in the retention tree group, gap and preparation cutting compared to the control. Based on our results it can be concluded that microclimate limited epixylic liverworts are very sensitive to the changes of forest canopy and therefore to the changes of air humidity. On the other hand, the survival of epiphytes, which can tolerate less humid conditions, are less threatened by forest management. The study was supported by the Hungarian Research Found (OTKA 111887)

T-2 mycotoxin slows down the development of mouse blastocysts, decreases their blastomere number and increases chromatin damage

The mycotoxin T-2 has many harmful effects on mammalian cells and reproductive functions. In the present study, the in vitro effect of T-2 toxin on mouse blastocysts was examined. Embryos were cultured in media supplemented with 0.5, 0.75 and 1 ng/ml T-2. Different exposure times were applied [96 h (treatment I) or 24 h following 72 h in toxin-free media (treatment II)]. Blastomere number, nuclear chromatin status and blastocoel formation were investigated in blastocysts. Our data show that the effect of T-2 toxin may vary depending on the stage of the embryo at the start of exposure. At 96 h of exposure, the blastocysts had blastomeres with normal chromatin quality but their developmental potential was decreased. After 24 h of exposure applied following a 72-h culture, blastomeres had a higher level of chromatin damage, although their developmental potential was the same as in the control embryos. In both cases, decreased mitotic rate was found, which resulted in decreased blastomere number even at low toxin concentration

A korallzátonyok helyzete a globális klímaváltozás tükrében

A korallzátonyok a tengerek leglátványosabb, legváltozatosabb, és legösszetettebb ökológiai rendszerei. A sokféle korallból felépülő építészeti műremekek az összes tengeri élet negyedrészét tartják fenn. Hatalmasra nőhetnek. Méretük mellett a hasznosságuk is óriási: többek között „nyelik” és forgatják a légkör szén-dioxid-tartalmát, több mint egymillió tengeri fajnak nyújtanak életteret, élelmet biztosítanak a szigetlakóknak a trópusokon, enyhítik a tengeri viharok hatását; élelemmel és gyógyszerforrásokkal segítik az embereket. „Habár az élet forgatókönyve az életben maradásért folytatott heves küzdelmekkel teli, a korall élőhelyek mégis lakosaik és a zátonyépítő organizmusok közötti dinamikus egyensúllyal jellemezhetők, mely egy több ezer éves időskálán a zátonyok növekedéséért, szigetek, atollok kialakulásáért felelősek.”1 Természetes körülmények – mint a tengerszintváltozások, szeizmikus mozgások, vulkánkitörések, trópusi viharok – időről-időre befolyásolták a korallzátonyok fejlődését, de rugalmasságuknak köszönhetően, mindig túlélték ezeket a stresszhatásokat. Mai világunkban azonabn a változások gyorsan és leggyakrabban ökológiai szempontból kedvezőtlen irányba hatnak. Azok az emberi – népességnövekedésből, gazdasági- és technikai fejlődésből adódó – tényezők, melyek hatással vannak a tengeri ökoszisztémákra, túl gyakran követik egymást és túl intenzív lefolyásúak ahhoz, hogy a korallközösségek ezeket „kiheverhessék”. A korallzátonyok az 1990-es években kezdődő kutatások szerint nagy veszélyben vannak. A korallok – hasonlóan a sarki jégtakaróhoz és a gleccserekhez – rendkívül érzékenyek a hőmérsékletre. Ily módon nagyon jó közvetlen indikátorai a klímaváltozás globális hatásainak. A nyári csúcshőmérséklet már akár egy foknyi emelkedése is a korallok kifehéredését okozza. A kifehéredést gyorsuló ütemben követi a korallok tömeges pusztulása. Az ausztráliai Nagy Korallzátony 10%-a mára eltűnt. Ha a hőmérséklet a jelenlegi ütemben emelkedik tovább, egyes kutatók lehetségesnek tartják, hogy a következő 50 évben az összes korallzátony eltűnik a világ óceánjaiból. A globális átlaghőmérséklet emelkedése csupán a krízishelyzetet előidéző okok egyik aspektusa. A korallzátonyok pusztulásánál más tényezők is szerepet játszanak, melyek egy része a klímaváltozástól független antropogén hatás, más részük viszont szoros, ok-okozati összefüggésben áll a változó éghajlattal. Dolgozatomban a korallzátonyok pusztulásáért felelős tényezőket szeretném megvizsgálni, illetve választ keresek arra, hogy mit lehet tenni e folyamat visszaszorítása és a károk enyhítése érdekében