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An important problem in metagenomic data analysis is to identify the source organism, or at least taxon, of each sequence. Most methods tackle this problem in two steps by using an alignment-free approach: first the DNA sequences are represented as points of a real n-dimensional space via a mapping function then either clustering or classification algorithms are applied. Those mapping functions require to be genomic signatures: the dissimilarity between the mapped points must reflect the degree of phylogenetic similarity of the source species. Designing good signatures for metagenomics can be challenging due to the special characteristics of metagenomic sequences; most of the existing signatures were not designed accordingly and they were tested only on error-free sequences sampled from a few dozens of species.In this work we analyze comparatively the goodness of existing and novel signatures based on tetranu-cleotide frequencies via statistical models and computational experiments; we also study how they are affected by the generalized Chargaff’s second parity rule (GCSPR), which states that in a given sequence longer than 50kbp, inverse oligonucleotides are approximately equally frequent. We analyze 38 million sequences of 150 bp-1,000 bp with 1% base-calling error, sampled from 1,284 microbes. Our models indicate that GCSPR reduces strand-dependence of signatures, that is, their values are less affected by the source strand; GCSPR is further exploited by some signatures to reduce the intra-species dispersion. Two novel signatures stand out both in the models and in the experiments: the combination signature and the operation signature. The former achieves strand-independence without grouping oligonucleotides; this could be valuable for alignment-free sequence comparison methods when distinguishing inverse oligonucleotides matters. Operation signature sums the frequencies of reverse, complement, and inverse tetranucleotides; having 72 features it reduces the computational intensity of the analysis.

Jets are a common way to transfer mass among fluids, or from a fluid to a surface. At moderate Reynolds numbers and low turbulent intensities the jet exhibits a Near Field Region (NFR) several diameters long. The paper presents numerical results and a theoretical model for the passive scalar diffusion of a submerged free jet in the NFR. Large Eddy Simulations (LES), in the Reynolds number range of 5000–40,000 and the Schmidt number range 1–100, are performed obtaining the passive scalar fields. Three mathematical models for the passive scalar diffusion are presented; the first one is valid in the NFR, specifically in the Undisturbed Region of Flow (URF), and the other two, obtained under the hypotheses of Tollmien and Gortler momentum spreading, are valid in the Potential Core Region (PCR). The last two models employ a turbulent Schmidt number inversely proportional to the mean velocity gradient, conclusion obtained from the LES numerical results. The self-similar solutions of the passive scalar show good agreement with the LES results. The wide range of Reynolds and Schmidt numbers investigated gives generality to the results.

The influence of the degree of residual stenosis on the hemodynamics inside coronary arteries is investigated through three-dimensional (3D) numerical simulations. The present paper, which is the first of a series of two, focuses on the influence that the degree of residual stenosis (DOR) has on the fluid dynamics and the shear stresses acting on the stent and the artery wall. The pulsatile nature of the blood flow and its non-Newtonian features are taken into account. Four models of artery are investigated. The results show that the wall shear stress (WSS) increases monotonically, but not linearly, with the DOR.

Can we exploit our burgeoning understanding of molecular evolution to slow the progress of drug resistance? One role of an infection clinician is exactly that: to foresee trajectories to resistance during antibiotic treatment and to hinder that evolutionary course. But can this be done at a hospital-wide scale? Clinicians and theoreticians tried to when they proposed two conflicting behavioral strategies that are expected to curb resistance evolution in the clinic, these are known as “antibiotic cycling” and “antibiotic mixing.” However, the accumulated data from clinical trials, now approaching 4 million patient days of treatment, is too variable for cycling or mixing to be deemed successful. The former implements the restriction and prioritization of different antibiotics at different times in hospitals in a manner said to “cycle” between them. In antibiotic mixing, appropriate antibiotics are allocated to patients but randomly. Mixing results in no correlation, in time or across patients, in the drugs used for treatment which is why theorists saw this as an optimal behavioral strategy. So while cycling and mixing were proposed as ways of controlling evolution, we show there is good reason why clinical datasets cannot choose between them: by re-examining the theoretical literature we show prior support for the theoretical optimality of mixing was misplaced. Our analysis is consistent with a pattern emerging in data: neither cycling or mixing is a priori better than the other at mitigating selection for antibiotic resistance in the clinic. Key words: antibiotic cycling, antibiotic mixing, optimal control, stochastic models.

Heat conduction in two and three-phase media, composed of solid spherical particles of the same diameter, is investigated theoretically and experimentally. The theoretical model has no empirical constants and is based on the solution of the Fourier heat conduction equation, under the thermal assumption of parallel heat fluxes, in porous medium with porosity greater than 0.4764. The medium can be two-phase, fully saturated with water or air, or three-phase, partially saturated with water and air. The problem is investigated experimentally with the thermal probe, a vertical cylinder inserted into the glass beads of the diameter of 3 mm. The thermal probe, made in laboratory, has a diameter of 1.5 mm and length 150 mm, and contains an electric heater and a temperature sensor. The perfect line source theory in the transient regime is employed to measure the thermal conductivity of the water saturated glass beads. The theoretical results for the two-phase media, glass beads and water, are in good agreement with the experiments. The results of the theoretical model for the three-phase media, glass beads with water and air, are in good agreement with the experimental data of the literature, and are compared to several theoretical models of the literature.

Problems concerning services in an AAL kitchen environment are discussed. The complexity of their accurate specification is outlined. An example of implementation is described.

Numerical simulations of three configurations of a modified Trombe-Michel Wall (TMW) are carried out and the numerical results are employed to carry on the energy and exergy analyses. The three configurations of the modified Trombe-Michel Wall (TMW) investigated are with sharp edges, with rounded edges and with the guided flow. For each configuration and glaze spacing, spanning from 0.1 m up to 0.5 m, the velocity and the mean air temperature in the channel, the heat flux, the exergy gain and the conductive heat transfer through the massive wall are evaluated numerically. The comparison among the three configurations shows that the guided flow presents the highest energy and exergy efficiency.

The paper employs a theoretical model to evaluate the thermal conductivity of composites under two thermal assumptions which allow to solve the heat conduction equation. The composite is made of a ceramic-silica matrix and a fiber reinforcement. Three different materials are investigated as reinforcement, i.e. asbestos, steel and copper. The theoretical effective thermal conductivity is calculated along the three directions for a non-consumed composite and during its consumption. Numerical solutions of heat conduction in the composite are carried out. The anisotropy degree of the composite is investigated for the composite during its consumption. The anisotropic efficiency of the composite is defined as ratio between the anisotropy degree of the composite and the potential anisotropy of the two materials, i.e. the ratio between the thermal conductivity of the fiber and the matrix. The theoretical model allows to evaluate, under the two thermal assumptions, the anisotropic efficiency of the composites which decreases with the increase of the potential anisotropy reaching a minimum, which is only dependent on the geometry of the composite.

The mass and energy-capital conservation equations are employed to study the time evolution of mass and price of nonrenewable energy resources, extracted and sold to the market, in case of no-accumulation and no-depletion, that is, when the resources are extracted and sold to the market at the same mass flow rate. The Hotelling rule for nonrenewable resources, that is, an exponential increase of the price at the rate of the current interest multiplied the time, is shown to be a special case of the general energy-capital conservation equation when the mass flow rate of extracted resources is unity. The mass and energy-capital conservation equations are solved jointly to investigate the time evolution of the extracted resources.

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. Self-Similarity in turbulent round jets has been the object of investigation from several decades. The evolution of turbulent submerged jets is characterized by the presence of two regions: the region of flow establishment, or near field region (NFR) and the fully developed region (FDR), or far-field region (FFR). The momentum spreading in the FDR is known to be self-similar and few mathematical models have been presented in the past to describe it. The flow evolution in the NFR has been rarely studied since there is a certain consensus on the idea that the flow in the NFR is not self-similar. In this work, we study the flow evolution of a turbulent submerged round jet by means of large eddy simulation (LES) at several Reynolds numbers ranging from 2492 to 19,988. Three new self-similar laws are proposed to describe the flow evolution in the NFR, one for the initial region, called Undisturbed Region of Flow, (URF), and two for the final region, the potential core region (PCR). The numerical results presented in this work are also validated with the self-similar laws for the FDR proposed by Tollmien (1926) and Görtler (1942), and the experimental data of Hussein et al. (1994), and Panchapakesan and Lumley (1993), in the FDR; those of Davies et al. (1963), in the PCR; and van Hout et al. (2018), in the URF. The conclusion is that previous inability to find the self-similarity law in the NFR is due to the attempt to find a unique self-similar variable to describe the momentum spreading in both the URF and the PCR.

The two main problems in the cooling of a cylinder with a rectangular jet of the same width are the choice of the jet height and the distance between the jet exit and the cylinder. The present paper presents experimental measurements of the heat transfer on a cylinder, with diameter D = 10 mm, cooled by rectangular jets with low turbulence, the same width of the cylinder but different height, H, 2.5 and 5 mm, respectively, in order to study their influence on the local and the mean cooling rates. The cylinder to be cooled is heated by electric current and is set on the symmetrical plane of symmetry, i.e. the geometry is two-dimensional, at several distances from the jet exit, x, in order to find the position which realizes the maximum heat transfer. The experimental measurements of the local heat transfer are performed along the circumference of the cylinder at several angles from the impingement for Reynolds number, defined with the cylinder diameter, D, and the average velocity, in the range ReD = 5000–22,000. The comparison between the two slots is performed at the same Reynolds number, ReD, which means that the smaller slot has a slightly greater maximum velocity. The experiments show that on the impinging point the local Nusselt number is greater for the slot with H = 2.5 mm, while at greater angles from the impingement, i.e. 45°, 90°, 135° and 180°, the local Nusselt numbers have different behaviors. The mean Nusselt numbers are similar for the two slots, at the same Reynolds number, ReD. Local and mean Nusselt numbers, obtained with the two jets, are in qualitative agreement if they are compared with the dimensionless distance, x/H, which can be interpreted as the ratio of the Reynolds numbers, Rex/ReH, independent of the mass flow rate or per unit of mass flow rate. The maximum of the local Nusselt number on the impinging point is obtained at greater distances for smaller Reynolds numbers, e.g. in the range from x/H = 15 at Re = 5000 to x/H = 9 at Re = 22,000, while the distance is shorter along the cylinder at greater angles from the impingement. The maximum of the mean Nusselt number is similar to that on the impingement for the two jets. The experimental heat transfer is also examined from the point of view of the slot efficiency, i.e. taking into account the mechanical power necessary to move the fluid in the slot jet. The conclusion is that the smaller slot, H = 2.5 mm or D/H = 4, has a greater efficiency as cooling system because it removes more heat at the same mechanical power.

The evolution of turbulent rectangular submerged free jets has been investigated numerically with a two-dimensional (2D) approach by the present authors and, by using the large eddy simulations (LES) at several Reynolds numbers. The average numerical results confirmed the presence of the undisturbed region of flow (URF) located between the slot exit and the beginning of the potential core region (PCR) previously observed experimentally at the University of Rome “Tor Vergata” by Gori and coworkers. The 2D study of the present authors carried out under the conditions previously investigated in the literature, showed that the URF has a self-similar behavior, and proposed a new law for the evolution of the momentum. The present paper extends the LES to three-dimensional (3D) rectangular submerged free jets, in the range from Re = 5,000 to Re = 40,000, showing that the self-similar behavior of URF is also present in the 3D numerical simulations, as well as in the PCR and in the fully developed region (...

The effect of a lateral discontinuity in the thermal boundary conditions in two dimensional laminar flow on a flat plate is investigated with numerical and analytical modeling. When the thermal and momentum boundary layers start at the same location, the resulting self-similar two dimensional boundary layer equations were solved numerically. For flow with an unheated starting length, three dimensional numerical simulations were required. For both the two and three dimensional thermal simulations, the Blasius solution for a two dimensional momentum boundary layer was assumed. It is found that all the Nusselt numbers collapse to a single curve when graphed as a function of a spanwise similarity variable. Simple correlations for the local Nusselt number on a rectangular flat plate are presented for a variety of boundary conditions.

In the "Design4All" project, a hardware and software architecture is under development for the implementation of adaptable and adaptive applications aimed to support all people in carrying out an independent life at home. In this paper, the problems of interactions with applications implemented in the Android platform, chosen for the experiments of interaction with the developed applications, are discussed with main emphasis on two main aspects: (i) the use of facilities supporting accessibility available in the most commonly used operating systems (mainstreaming) and (ii) the portability of solutions across different platforms.

The present work investigates the average heat transfer on a finned cylinder cooled by a rectangular jet of height H. The diameter of the external cylinder, without fins, is D and the cylinder to slot ratio D/H is equal to 1. Numerical simulations are carried on with two turbulent models, RNG k–ɛ and SST k–ω. The jet flow can be characterized by the Reynolds number, defined with the diameter of the external cylinder without fins, D, or with the hydraulic diameter of the rectangular slot, Dhydr ≈ 2H. Two turbulent flows are investigated at ReD = 7100, or ReDhydr = 13,200, and at ReD = 19,700, or ReDhydr = 36,700. The main goal of the paper is to evaluate the optimal spacing, s, between the fins, and the optimal slot-to-cylinder distance, S/H, which maximize the average heat transfer on the finned cylinder. The optimization process is performed for a pitch of 3 mm and at a given value of the fin volume. The numerical simulations show that an optimal configuration is obtained when the ratio s/l of the spacing, s, to fin height, l, is maximum, and the cylinder is set at the slot-to-cylinder distance, S/H = 3.

L'attività A4.26, a partire dalle specifiche di progetto ampiamente descritte nel deliverable A4.18, è stata conclusa con la realizzazione di un prototipo su tablet. Tale prototipo fornisce una serie di servizi relativi all'ambiente cucina, relativi a quattro sezioni fondamentali quali il ricettario, il diario, la dispensa e gli elettrodomestici, che coprono la maggior parte delle attività svolte dall'utente in tale ambiente, come descritto dalla classificazione internazionale delle Funzionalità e Disabilità dell'Organizzazione Mondiale della Sanità (WHO ICF) [5]. L'applicazione realizzata è stata personalizzata per quattro tipi di utenti, normodotati, utente con disabilità visiva (ipovedente), utente con disabilità motoria, utente con lieve disabilità cognitiva. Inoltre è stata inserità la possibilità di attivare alcuni comandi di accessibilità direttamente dall'applicazione.

The present work is aimed to evaluate the effective thermal conductivity of an ablative composite material in the state of virgin material and in three paths of degradation. The composite material is undergoing ablation with formation of void pores or char and void pores. The one dimensional effective thermal conductivity is evaluated theoretically by the solution of heat conduction under two assumptions, i.e. parallel isotherms and parallel heat fluxes. The paper presents the theoretical model applied to an elementary cubic cell of the composite material which is made of two crossed fibres and a matrix. A numerical simulation is carried out to compare the numerical results with the theoretical ones for different values of the filler volume fraction.

The present work deals with the enhancement of heat transfer on a cylinder due to the turbulence of the impinging jet. Experiments are carried out to cool a smooth cylinder, electrically heated, with a submerged slot jet of air at Reynolds numbers equal to Re = 4180 and Re = 7630. The increase of turbulence is obtained by the introduction of a metallic grid and by the natural evolution of the jet with the distance from the slot exit. Turbulence, velocity and heat transfer measurements are presented in order to show the relation with the slot-to-cylinder distance. The metallic grid is set in two positions: just on the slot exit or at a constant distance in front of the cylinder. In the natural evolution of the free jet the turbulence increases with the distance because of the interaction with stagnant air, reaches a maximum and then decreases. If the grid is on the slot exit the turbulence increases at first, then decreases according to the degeneration law, and finally increases again due to the interaction with the stagnant air. Turbulence at a distance of 10 times the slot height is about the same whether is present or not the grid. Heat transfer measurements are presented as local and mean Nusselt numbers. Without grid local and mean Nusselt numbers increase with the distance from the slot exit reaching the maximum at a distance of about 8 time the slot height. With the grid on the slot exit the local Nusselt number has a maximum immediately after the grid and a minimum at 4–5 time the slot height. With the grid in front of the cylinder at the distance of the slot height the local Nusselt number has the maximum immediately after the grid and then is about constant up to 10 times the slot height. The mean Nusselt number with the grid in front of the cylinder is greater than without the grid only at the higher Reynolds number experimented.

This work presents new experimental results in the cooling of an externally finned cylinder with a submerged slot jet of air. Two slots are employed with D/H equal to 2 and 4, where D is the diameter of the cylinder without fins and H the slot height. Local and mean Nusselt numbers are evaluated at several Reynolds numbers and distances from the slot exit. Empirical expressions are proposed to correlate the experimental mean Nusselt numbers and the convective heat transfer coefficients. The two slots are compared also according to the concept of efficiency, which takes into account the cooling rate and the mechanical power necessary to drive the flow.

A new equation for the dissipation rate of turbulent kinetic energy is derived exactly in conservative form for a Generalized Newtonian Fluid (GNF). The transport equations for mass, momentum, and turbulent kinetic energy are written along to the transport equation for the shear rate. A new transport equation for the apparent viscosity is derived assuming the viscosity as dependent only on the shear rate. The assumption is of incompressible two-dimensional GNF flow.

The price evolution of non-renewable resources versus the consumption rate is investigated with the aim of constructing the energy supply curve. The case studied is without accumulation nor depletion of the resources and the mass and energy-capital conservation equations are solved under the condition of the same mass flow rate of extraction and sale. The energy supply curve of extracted resource is dependent on the newly defined parameter, RINE, Rate of Interest of Non-extracted resources on the Extraction rate. The energy supply curve of sold resource is dependent on the newly defined parameter, RISE, Rate of Interest of Sold resources on the Extraction rate, in case the rate of interest of non-extracted resources, rN, is nil. In general, the energy supply curve of sold resource is dependent also on two dimensionless parameters, Dimensionless Critical Initial Price of Sold resources, i.e. DCIPS, and Dimensionless Critical Initial Price Extreme of Sold resources, i.e. DCIPES. The energy supply curve of sold resources is investigated under different relations between three parameters, i.e. extraction rate and interest rates of non-extracted and extracted/sold resources. New trends are observed in the economic market of non-renewable energy resources. The energy supply curve of the difference between sold and extracted resource is also obtained and is dependent on two dimensionless parameters, Critical Initial Price Difference, i.e. CIPD, and Critical Extreme of the Initial Price Difference, i.e. CEIPD. Finally, the predictions obtained with the present approach are compared to the real evolution of the world price of oil and the European price of gas versus the world consumption during the last three decades, i.e. from 1980 until 2005 for oil and from 1984 until 2005 for gas, taking into account inflation, discount and prime rates of the economic market. The agreement is acceptable but, more important, the trend is correctly predicted. The price difference between sold and extracted resources is also investigated versus the dimensionless mass flow rate of extraction. The evolution is dependent on four parameters: RINE, RISE, DCIPS, and DCIPES.

According to the current literature on the cooling of two cylinders in row, by a uniform flow of air, the first cylinder is always a heat transfer promoter versus the second one. The aim of the present paper is to summarize the state of art of the literature on the cooling of two cylinders in row by a slot jet of air. Additional experiments are carried on in order to investigate the possible application of jet cooling to heat transfer apparatuses, including electronics, in order to study the positions of the two cylinders in row which realize the same heat transfer on each cylinder. In the experiments a slot jet of air with low turbulence is employed with a slot height, S , equal to the impinged cylinder diameter, D , i.e. D / S = 1.0. The first cylinder is set at two distances H from the slot exit, H / S = 4 and 6, while the distance of the second cylinder from the first one, L , is variable from L / S = 2–11. The Reynolds number, Re , defined with the cylinder diameter D , spans in the range Re = 11,000–22,200. If the first cylinder is set at the dimensionless distance from the slot exit which realizes the maximum mean heat transfer on the first cylinder, i.e. H / S = 6, the second one has generally a lower mean Nusselt number. The only exception is when the second cylinder is set at the dimensionless distance L / S = 4 and the Reynolds number is at the maximum value experimented, i.e. Re = 22,200. If the first cylinder is set at the dimensionless distance H / S = 4 the mean Nusselt number on the second cylinder is greater if its distance from the first one is in the range L / S = 3.5–7 for Re = 14,300–22,200. The first cylinder acts as a heat transfer promoter, as happens in uniform flow, only for Re = 22,200.

Efficacy of epidural local anesthetics plus steroids for the treatment of cervicobrachial pain is uncertain.A prospective study randomized 160 patients with cervicobrachial pain resistant to conventional therapy. Patients were divided into 4 groups on the basis of the time between pain onset and treatment initiation: group A, 40 patients with pain onset 15 to 30 days; group B, 40 patients with pain from 31 to 60 days; group C, 40 patients, 61 to 180 days; and group D, 40 patients with pain180 days. Patients of each group were randomized to receive an epidural block with bupivacaine and methylprednisolone at intervals of 4 to 5 days (Single injection) or continuous epidural bupivacaine every 6, 12, or 24 hours plus methylprednisolone every 4 to 5 days (Continuos epidural). The maximum duration of treatment (9 blocks in Single injection, and 30 days in Continuos epidural) was dependent on achieving Pain Control (PC)or =80% [PC is defined by this formulae: (100) (VAS(initial)-VAS(final))/VAS(initial)]. Follow-up at 1 month and 6 months compared PC and the number of pain-free hours of sleep.One hundred forty-one patients completed the study. The 4 groups had similar characteristics. At the 1-month and 6-month follow-up analysis based on the time between pain onset and treatment initiation showed that patients of group D, who received the Continuous epidural treatment, had significantly greater PC and significantly more pain-free hours of sleep compared with similar patients in Single injection.Therapy with continuous epidural local anesthetic and methylprednisolone provides better control of chronic cervicobrachial pain compared with Single injection. These results are discussed with respect to the possible mechanism of action of the drugs and may relate to the physiopathologic mechanisms associated with neuronal plasticity that result in chronic pain.

Flow visualisation and heat/mass transfer measurements in a linear turbine cascade with tip/casing clearances ranging from 0.60% to 6.90% of chord show the influence of blade tip geometry for a standard flat tip, a squealer tip and a geometry with a winglet on the pressure side and a squealer on the suction side of the blade. Oil-lampblack and oil-dot techniques show the surface flow on the blade endwall and tip while a laser light-sheet and a smoke wire indicate the three-dimensional flow in the tip clearance and blade passages. Local heat/mass transfer from the blade tips is measured using the naphthalene sublimation technique. Experiments with the standard flat tip blade clearly show that a separation bubble exists at the pressure side edge of the tip surface at all tip clearance levels. The effect of the tip leakage vortex on the secondary flows in the blade passage is also evident: with an increase of tip clearance, the horseshoe vortices disappear while the passage vortex is weakened and pus...

The evolution of turbulent rectangular submerged free jets is described in the literature by the presence of two regions of flow: the potential core region (PCR) and the fully developed region (FDR). However, experiments carried out in the last decade showed that a third region of flow is present, the undisturbed region of flow (URF), so-called in the average visualization, or the negligible disturbances flow (NDF) plus the small disturbances flow (SDF), so-called in the instant visualization. The URF is located between the slot exit and the beginning of the PCR. The main characteristics of URF, and NDF, are that velocity and turbulence profiles remain almost equal to those measured on the slot exit, and the height of the jet remains equal to the slot one. In the SDF the jet height undergoes small variations, i.e., contractions or expansions, but without formation of the vortex. To date, no numerical evidence of the presence of URF has been given by the literature. The present study, which concerns a two-dimensional jet, presents Large Eddy Simulations (LES), carried out at four Reynolds numbers, which are able to predict and characterize URF. The present numerical results are compared to previous theoretical approaches and confirm the presence of URF, between the slot exit and the PCR. Moreover, URF has a self-similar behavior and a new law for the evolution of the momentum is proposed.

The present work studies the enhancement of heat transfer on a cylinder impinged by a rectangular jet in presence of a metallic grid on the slot exit. The experiments are carried out to cool a smooth cylinder, electrically heated, with a rectangular jet of air, at three Reynolds numbers in turbulent flow, i.e. Re = 5100, 10,600 and 15,300, where the Reynolds number is defined with the cylinder diameter. Three metallic grids, identified by the French classification as NF06-10-20, are employed with the solidity ratio ranging from 24.3% to 67.7%, and the same diameter of the mesh filament (0.6 mm). Fluid dynamic measurements, performed with a hot film anemometer, are done to justify the thermal results. Heat transfer measurements are presented as local and mean Nusselt numbers. The comparison with the case without grid, indicated as NF00, is done at the same mass flow rate of the jet and the same power consumption of the wind tunnel to move the jet. The main goal of the paper is to evaluate how the solidity ratio of the metallic grids influences the heat transfer.

A theoretical investigation is carried out to study natural convection around a vertical thin cylinder, or a needle, heated at uniform and constant wall heat flux in order to compare the analytical solutions of the present work with previous experimental results. The local non-similarity solution with the first level of truncation, proposed by Minkowycz and Sparrow, is used. The temperature and velocity distributions are calculated for fluids with several Prandtl numbers. The analytical solutions of this work are compared to experimental results carried out with needles of diameters ranging from 0.6 to 1.5 mm and fluids with Prandtl numbers in the range Pr = 0.7–730. The agreement is reasonable good.

The time evolution of the price of resources sold to the market and of the price difference, between sold and extracted resources, is investigated in case of no accumulation of the resources; i.e. when the resources are extracted and sold to the market at the same mass flow rate. The price evolution of sold resources varies with time according to the relation between the price increase factor, PIF, of sold and extracted resources. The price evolutions of sold resources and price difference are investigated according to the relation between extraction rate and interest rate of extracted and sold resources. The price of sold resources and the price difference increase with time if the PIF of sold resources is greater than the PIF of extracted resources and the initial price is greater than the critical price of sold resources, which depends on the initial price of extracted resources and the interest rate of non-extracted and extracted resources. The price of sold resources and the price difference decrease with time if the PIF of sold resources is greater than the PIF of extracted resources and the initial price is smaller than the critical price of sold resources. The other cases are discussed extensively in the paper.

The electrical resistivity (ER) of Flexinol nickel-titanium shape memory alloys (SMA) has been measured in the range from -15 to 105 degrees C. The investigated Flexinol wires have two diameters, 150 and 375 mu m. The experimental results show new temperatures of phase transformation (TTR) evidencing the unexpected presence of the R-phase. The transformations from austenite to martensite, from austenite to R-phase, and vice versa are simultaneous. In the range [20 to 110 degrees C] the hysteresis is almost negligible, whereas in the range [-15 to 105 degrees C] the accommodation process of the hysteresis is observed.

A submerged slot jet of air is used as cooling system for an externally finned cylinder ensemble, heated by electric current. The cylinder ensemble is made with a stainless steel finned tube and a Teflon® bar as core. Five thermocouples, pressed inside the steel tube by the Teflon bar, measure the wall temperature in order to determine local and mean convective heat transfer coefficients. The local Nusselt number has its maximum on the impinging point and its minimum on the opposite position. The variation of the local and mean Nusselt number with the distance from the slot exit is investigated. An empirical expression is proposed to correlate the experimental data. The cooling with a jet flow of a finned cylinder realizes a higher heat transfer as compared to that of a smooth cylinder.

Experimental results are presented for heat transfer cooling of an electrically heated circular cylinder, of diameter D=10 mm, by a slot jet, of height S=2.5 mm, i.e. with D/S=4. Mean and local Nusselt numbers are presented versus the Reynolds numbers, the distance of the cylinder from the slot exit, H, and the angle from the impinging point. Mean Nusselt numbers, defined according to the cylinder diameter, D, are higher than the values in an infinite flow. The maximum mean Nusselt number is measured when the cylinder is set at a distance H, from the slot exit, such that H/S=8. The minimum local Nusselt number is measured at an angle of 180° from the impinging point, i.e. on the rear of the cylinder. Comparisons have been done among the mean Nusselt numbers of this work and previous experimental results of the same authors, carried out with diameter to slot height ratios equal to D/S=1 and 2. The conclusion is that the mean Nusselt number, defined as , is higher for D/S=4, versus the Reynolds number, defined as ReD=WD/ν. On the contrary, the mean Nusselt number, defined on the basis of the slot height, , has similar values, for the different slot heights, versus the Reynolds number, defined as ReS=WS/ν, with the trend of higher results for the slot with D/S=2.

The thermal conductivity of olivine, dry and mixed with water, up to saturation, has been measured with a thermal probe, using the step heating method. The olivine is composed of solid particles with dimensions in the range from 0.8 to 1 mm. Dry olivine has been measured in the range of temperatures between −17° to +50°C. Olivine mixed with water has been measured at +50°C. The cubic cell model has been used to make predictions to compare with the measured data. Comparisons of the experimental thermal conductivities and the predicted values of dry and water-mixed olivine show good agreement. The cubic cell model can be used to evaluate the porosity of olivine and the thermal conductivity of the solid particles, from the values measured at dryness and saturation, with reasonably good agreement. In this way, it is not necessary to measure the mineral composition of the particles of the porous media. Also, the porosity of the medium is predicted with reasonable agreement, which takes into account the phenomenon of the porosity increase near the probe, since the diameter of the probe is smaller than that of the solid particles.

The paper presents numerical simulations of heat conduction around a circular vertical cylinder immersed in liquids. A finite volume formulation is used, and the numerical analysis is performed in unsteady state with an explicit scheme. The numerical predictions are compared with experiments performed on liquids to find the temperature inside the cylinder, where a thermocouple is located, and at the wall of the insulated coaxial container, where the liquid is poured. The cylinder is immersed vertically. The numerical results are in good agreement with the temperature at the wall of the container. The experimental temperature measurement of the thermocouple located inside the probe is intermediate between the numerical temperatures on the axis and on the surface of the probe. The natural convection phenomenon is evidenced in the experiments, after a certain time from the beginning of heating, in some of the liquids used, except glycerol. Natural convection is not considered in the present numerical simulations, which solve only the heat conduction equation.

The theoretical model of the present paper assumes the unit cell of the porous medium as composed of a cubic space with a cubic solid particle at the center. The thermal conductivity is evaluated by solving the heat conduction equation with the assumption of parallel isotherms within the cubic space. The liquid water in the porous medium is distributed around the solid particle according to the phenomena of adsorption and capillarity. The thermal conductivity of the gas present within the pores takes into account the thermal conductivity of the water vapor and dry air, without enhanced vapor diffusion. The model simplifies the variation of the relative humidity, from dryness to the field capacity, with a linear increase. The predicted results, compared to experimental data, show the agreement is very good at the temperatures in the range (30–50°C) and acceptable at 70°C. At high temperature (90°C) the predictions are higher than the experiments and a better agreement could be obtained by decreasing the thermal conductivity of the gas phase. Besides, the trend of the theoretical predictions is in good agreement with the experiments also at high temperatures.

An analysis of measured soil thermal conductivity (λ) data for temperatures (T) varying from 5 to 90°C, was conducted with respect to four soil moisture content domains, i.e. residual, transitory meniscus, micro/macro porous capillary, superfluous. It was shown that each domain has a specific behaviour of λ vs soil moisture content (θ). For example, λ varies insignificantly with θ and T at very low moisture contents (residual moisture domain). In the transitory meniscus and micro/macro porous capillary domains, the relation λ (θ) shows in general a nonlinear behaviour, which is difficult to model, particularly at high T. A sensitivity analysis applied to the Gori (1983) model for dry soil showed better predictions when the model was restricted to the use of the first term only (dependent on soil porosity and thermal conductivity of air). Two linear λ approximations have been tested, across the second domain (from a critical θ to the permanent wilting point) and across the second and third domains (from a critical θ to field capacity). The enhanced model has been tested against soil λ data measured at moderate and high T. The numerical results show considerably improved predictions in the first three soil moisture domains. The first linear λ interpolation shows better agreement with experimental data for T up to 65°C, while the second interpolation was much more beneficial at higher T. The original Gori model gives generally the best predictions in the superfluous domain. Copyright © 2002 John Wiley & Sons, Ltd.

An inter-particle contact heat transfer model for evaluating soil thermal conductivity is analysed with respect to soils, representing different textural classes, exposed to moderate temperatures ranging from 15 to 30°C. This model is a combination of a self-consistent approximation model, enhanced with an inter-particle contact heat transfer correction coefficient. For dry and saturated soils, this coefficient is defined as a ratio of a soil harmonic mean thermal conductivity of solid and fluid (air or water) phases, to the average thermal conductivity of soil solid grains. For unsaturated soils, we assume a linear interpolation of the correction coefficient between absolutely dry and saturated states, with a Kersten function (Ke) as a proportional factor. The strongest impact of the correction coefficient (maximum reduction of heat transfer) is observed for coarse soils below a critical value of saturation degree (Sr-cr–corresponds to Ke≅0) followed by medium and fine soils. For Sr>Srcr, the reduction of heat transfer gradually diminishes as Sr approaches 1 (i.e. saturated state). Soil texture, soil specific surface area, porosity and mineralogical composition (particularly quartz content) are important factors influencing the heat transfer correction coefficient. Their influence appears to be more substantial at the lower half of the wetness range (Sr

We need to find ways of enhancing the potency of existing antibiotics, and, with this in mind, we begin with an unusual question: how low can antibiotic dosages be and yet bacterial clearance still be observed? Seeking to optimise the simultaneous use of two antibiotics, we use the minimal dose at which clearance is observed in an in vitro experimental model of antibiotic treatment as a criterion to distinguish the best and worst treatments of a bacterium, Escherichia coli. Our aim is to compare a combination treatment consisting of two synergistic antibiotics to so-called sequential treatments in which the choice of antibiotic to administer can change with each round of treatment. Using mathematical predictions validated by the E. coli treatment model, we show that clearance of the bacterium can be achieved using sequential treatments at antibiotic dosages so low that the equivalent two-drug combination treatments are ineffective. Seeking to treat the bacterium in testing circumstances, we purposefully study an E. coli strain that has a multidrug pump encoded in its chromosome that effluxes both antibiotics. Genomic amplifications that increase the number of pumps expressed per cell can cause the failure of high-dose combination treatments, yet, as we show, sequentially treated populations can still collapse. However, dual resistance due to the pump means that the antibiotics must be carefully deployed and not all sublethal sequential treatments succeed. A screen of 136 96-h-long sequential treatments determined five of these that could clear the bacterium at sublethal dosages in all replicate populations, even though none had done so by 24 h. These successes can be attributed to a collateral sensitivity whereby cross-resistance due to the duplicated pump proves insufficient to stop a reduction in E. coli growth rate following drug exchanges, a reduction that proves large enough for appropriately chosen drug switches to clear the bacterium., A laboratory treatment model shows that the sequentially alternating use of two antibiotics can be optimized to outperform combination treatments at the equivalent dose., Author Summary So-called “cocktail” treatments are often proposed as a way of enhancing the potency of antibiotics, based on the idea that multiple drugs can synergise when used together as part of a single combined therapy. We investigated whether any other multidrug deployment strategies are as effective as—or perhaps even better than—synergistic antibiotic combinations at reducing bacterial densities. “Collateral sensitivities” between antibiotics are frequently observed; this is when measures taken by a bacterium to counter the presence of one antibiotic sensitise it to the subsequent use of another. Our approach was to see if we could exploit these sensitivities by first deploying one drug, then removing it and instead deploying another, and then repeating this process. This is not an entirely new idea, and there is a precedence for this form of treatment that has been trialled in the clinic for Helicobacter pylori infection. The idea we pursued here is an extension of “sequential treatment”; we investigated whether with two antibiotics and n rounds of treatment, if we search within the set of all possible 2 n “sequential treatments”—including the two single-drug monotherapies—there might be treatments within that set that are more effective than the equivalent two-drug cocktail. Using a simple in vitro treatment model, we show that some sequential-in-time antibiotic treatments are successful under conditions that cause the failure of the cocktail treatment when implemented at the equivalent dosage.

The paper is aimed at investigating the influence of the Reynolds number on the instant flow evolution of a rectangular free jet of air in the range of Reynolds numbers from Re = 35,300 to Re = 2,200, where the Reynolds number, Re, is defined according to the hydraulic diameter, D, of a rectangular slot of height H, equal to about D = 2H. The Particle Image Velocimetry (PIV) technique allows obtaining the instant PIV visualizations on the central symmetry section of the rectangular jet. The visual inspection of the instant frames with one and two vortices, except for Re = 35,300 where only one vortex images are detected, shows that after the jet exit is present the Flow with Constant Instant Height, with a length LCIH which increases with the decrease of the Reynolds number, from a ratio LCIH/H equal to LCIH/H = 0.9 at Re = 35,300 to LCIH/H = 4.0 at Re = 2,200. The instant PIV measurements, carried out at several distances from the jet exit, show that the variations of the ratio U / U ‾ 0 of the centerline instant velocity, U, to the exit average velocity, U ‾ 0 , remain below ±4% for a length LCIV, defining the Flow with Constant Instant Velocity on the centerline. The ratio LCIV/H increases from LCIV/H = 1.1 at Re = 35,300 to LCIV/H = 4.1 at Re = 2,200 and is quite similar to LCIH/H. The instant PIV measurements of the centerline turbulence intensity, Tu, show that its variations remain below ±4% for a length LCIT, defining the Flow with Constant Instant Turbulence on the centerline. The ratio LCIT/H is equal to LCIV/H. The instant PIV velocity profiles in the transverse direction, are practically unchanged for a length LUVP which defines the flow with Unchanged Velocity Profile. The four lengths LUVP = LCIH = LCIV = LCIT are considered equal, defining the Flow with Negligible Disturbances, with length LND, or first type of flow, L1, which is in agreement with the average length of the flow with Constant Height, LCH, in the turbulent and laminar regime, and with the average length of the Undisturbed flow, LU, in the turbulent regime. The instant PIV frames show the presence, after the flow with negligible disturbances, of the Flow with Small Variations of the Height, where the jet height varies slightly without forming the vortex. The length of the flow with Small Variation of the Height is LSVH, and the first vortex appears after the total length (LND + LSVH). The variations of the instant PIV measurements of the centerline turbulence intensity, Tu, increase after the length LCIT, but remaining below ±5–9% for a length LSVT, which defines the Flow with Small Variation of the Turbulence. The total length (LCIT + LSVT) is comparable to (LCIH + LSVH) in the turbulent and laminar regimes, and can be assumed equal to the sum of the lengths of the flows with negligible and small disturbances, LND + LSD = L2, which is in agreement with the average length of the undisturbed flow, LU, in the laminar regime. The instant PIV frames show the flow with Coherent Vortices after L2, with a length LCV, followed by the vortices breakdown. The instant PIV frames allow visualizing the end of the flow with Coherent Vortices, defining the total length of the flows with negligible and small disturbances, and coherent vortices, as LND + LSD + LCV = L3, which is in good agreement with the average length of the potential core, LP.

The mass and energy-capital conservation equations have been used at the beginning of 2013 to forecast the monthly oil price up to December 2013. The approach of the interest rates has employed an interest rate equal to the arithmetic average between the prime and the discount rates. The present short communication comments the comparison between the forecast made during the middle of the 2013 and the real oil prices, as registered today, at the beginning of 2014.

Effective thermal conductivities of dry and water saturated glass beads have been measured with the transient thermal probe method. The glass beads used in the experiments have particles with diameters ranging from 0.07 mm to 6 mm. The thermal probe used for the measurements has an external diameter of 1.2 mm. The effective thermal conductivities of dry and water saturated glass beads, with diameters smaller than 1.2 mm, are well predicted by a theoretical model, proposed by the first author, which uses the experimentally measured porosity. If the diameter of the glass beads is 3 and 6 mm, i.e. it is higher than the probe one; the porosity of the porous medium is higher near the probe than in the core of the medium. The effective thermal conductivity of the porous medium is then lower because air and water have a lower thermal conductivity than the solid particles of the beads. A theoretical approach has been used in order to take into account the increase of porosity near the probe. The theoretical models use the corrected porosity, which account for the probe presence, and provide good agreement with the experimental measurements.

Heat transfer of slot jets of air impinging on the surface of a circular cylinder by forced convection has been investigated. The cylinder has a diameter of D=10 mm and the slot jet has a height of S=5 mm. The thermocouples, located along the surface of the cylinder, at various angles from the impinging point, allow the evaluation of the local convective heat transfer coefficients. The experiments have been performed for a Reynolds number of the impinging air ranging from Re=4000 to Re=20000. The influence of the distance H, between the exit of the slot jet and the cylinder, has been investigated in the range of H/S, H/S=2–10. The local Nusselt number is a function of the H/S ratio and of the angle from the front impinging point. It is also dependent on the Reynolds number.

BACKGROUND: Sequencing technologies have different biases, in single-genome sequencing and metagenomic sequencing; these can significantly affect ORFs recovery and the population distribution of a metagenome. In this paper we investigate how well different technologies represent information related to a considered organism of interest in a metagenome, and whether it is beneficial to combine information obtained using different technologies. We analyze comparatively three metagenomic datasets acquired from a sample containing the anammox bacterium Candidatus 'Brocadia fulgida' (B. fulgida). These datasets were obtained using Roche 454 FLX and Sanger sequencing with two different libraries (shotgun and fosmid). RESULTS: In each dataset, the abundance of the reads annotated to B. fulgida was much lower than the abundance expected from available cell count information. This was due to the overrepresentation of GC-richer organisms, as shown by GC-content distribution of the reads. Nevertheless, by considering the union of B. fulgida reads over the three datasets, the number of B. fulgida ORFs recovered for at least 80% of their length was twice the amount recovered by the best technology. Indeed, while taxonomic distributions of reads in the three datasets were similar, the respective sets of B. fulgida ORFs recovered for a large part of their length were highly different, and depth of coverage patterns of 454 and Sanger were dissimilar. CONCLUSIONS: Precautions should be sought in order to prevent the overrepresentation of GC-rich microbes in the datasets. This overrepresentation and the consistency of the taxonomic distributions of reads obtained with different sequencing technologies suggests that, in general, abundance biases might be mainly due to other steps of the sequencing protocols. Results show that biases against organisms of interest could be compensated combining different sequencing technologies, due to the differences of their genome-level sequencing biases even if the species was present in not very different abundances in the metagenomes.

The mass and the energy-capital conservation equations are employed to study the time evolution of the mass of oil and the oil price evolution with time of the resources sold to the market in case of no-accumulation and no-depletion of the resources; i.e. when the resources are extracted and sold to the market at the same mass flow rate. The time evolution of the monthly oil price is studied from January 1994 until December 2013, investigating the detailed forecast resulting from the application of the present theory. The oil price can be reasonably forecasted using the prime and the discount rate interests as extreme limits. The method is then applied to forecast the oil price during months when the economic rates are still unknown.

The aim of the present paper is to present a new model without empirical constants to evaluate the effective thermal conductivity of three-phase soils. In the model the soil is made of a quasi-spherical solid grain, and is surrounded by two phases, which can be air and water or air and ice. The effective thermal conductivity is obtained theoretically by the integration of the steady-state heat conduction equation under the thermal assumption of parallel heat fluxes. This new model allows to evaluate the effective thermal conductivity of soils with porosity (ratio between the volume of the voids and the total one) in the range between 0.0349 and 0.4734 at all degrees of saturation (ratio between the water volume and the void one) from dryness up to saturation. Comparisons with experimental data of unfrozen and frozen soils confirm that the model can predict the effective thermal conductivity with a fairly good agreement without using any empirical constant.

Mass conservation equation is employed to study the time evolution of the mass of oil in a reservoir, according to the actual mass flow rate of extraction. It is also possible to define the critical mass flow rate of extraction, which is the value exhausting the reservoir in an infinite time. The evolution with time of the price of the resources extracted and sold to the market is investigated in case of no-accumulation and no-depletion of the resources, i.e., when the resources are extracted and sold to the market at the same mass flow rate. The total energy conservation equation is transformed into a money or capital per time conservation equation, which allows to study the price evolution with time, which is dependent on the following parameters. The price evolution with time of the extracted resource is dependent on the parameter PIFE, “Price-Increase Factor of Extracted resource,” which is the difference between the basic interest rate of the capital, e.g., the inflation rate, and the mass flow rate of extraction. The price evolution with time of the sold resource is dependent on the parameter PIFS, “Price-Increase Factor of Sold resource,” which is the difference between the interest rate of the capital, e.g., discount or prime rate, and the mass flow rate of extraction. The parameter CIPS, “Critical Initial Price of Sold resource,” depends on the initial price of the extracted resource, on the interest rate of nonextracted resource, and on the difference between PIFS and PIFE. The parameter CIPES, “Critical Initial Price Extreme of Sold resource,” depends on the initial price of the extracted resource, on the interest rate of nonextracted resource, and PIFS. The time evolution of the oil price during the 8 months of 2009, when the inflation rate was negative, and following the economic crisis of 2008, is investigated introducing a new category of cases, i.e., the negative inflation rate one. The paper presents and discusses the results of the forecasting for different values of the interest rate of the capital, i.e., prime and discount rate, with the conclusion that the present theory can forecast the evolution of the oil price with a reasonable confidence using the prime and the discount rates as extreme limits.

The paper presents average flow visualizations and measurements, obtained with the Particle Image Velocimetry (PIV) technique, of a submerged rectangular free jet of air in the range of Reynolds numbers from Re = 35,300 to Re = 2200, where the Reynolds number is defined according to the hydraulic diameter of a rectangular slot of height H. According to the literature, just after the exit of the jet there is a zone of flow, called zone of flow establishment, containing the region of mixing fluid, at the border with the stagnant fluid, and the potential core, where velocity on the centerline maintains a value almost equal to the exit one. After this zone is present the zone of established flow or fully developed region. The goal of the paper is to show, with average PIV visualizations and measurements, that, before the zone of flow establishment is present a region of flow, never mentioned by the literature and called undisturbed region of flow, with a length, LU, which decreases with the increase of the Reynolds number. The main characteristics of the undisturbed region is the fact that the velocity profile maintains almost equal to the exit one, and can also be identified by a constant height of the average PIV visualizations, with length, LCH, or by a constant turbulence on the centerline, with length LCT. The average PIV velocity and turbulence measurements are compared to those performed with the Hot Film Anemometry (HFA) technique. The average PIV visualizations show that the region of constant height has a length LCH which increases from LCH = H at Re = 35,300 to LCH = 4–5H at Re = 2200. The PIV measurements on the centerline of the jet show that turbulence remains constant at the level of the exit for a length, LCT, which increases from LCT = H at Re = 35,300 to LCT = 4–5H at Re = 2200. The PIV measurements show that velocity remains constant at the exit level for a length, LU, which increases from LU = H at Re = 35,300 to LU = 6H at Re = 2200 and is called undisturbed region of flow. In turbulent flow the length LU is almost equal to the lengths of the regions of constant height, LCH, and constant turbulence, LCT. In laminar flow, Re = 2200, the length of the undisturbed region of flow, LU, is greater than the lengths of the regions of constant height and turbulence, LCT = LCH = 4–5H. The average PIV and HFA velocity measurements confirm that the length of potential core, LP, increases from LP = 4–5H at Re = 35,300 to LP = 7–8H at Re = 2200, and are compared to the previous experimental and theoretical results of the literature in the zone of mixing fluid and in the fully developed region with a good agreement.

The aim of the present paper is to determine the effective thermal conductivity of three-phase soils, made of a quasi-spherical solid grain, and surrounded by two phase, which can be water and air or water and ice. The effective thermal conductivity is obtained theoretically by integrating the conduction equation under the thermal distribution of parallel heat fluxes in steady-state. The effective thermal conductivity is evaluated at a given degree of porosity (ratio between the void volume and the total one) and different degrees of saturation (ratio between the water volume and the void one) from dryness up to saturation. Comparisons between experimental data and theoretical predictions confirm that the present model can predict the effective thermal conductivity with a fairly good agreement without using any empirical constant.Copyright © 2012 by ASME

Mass conservation equation is employed to study the time evolution of the mass of oil remaining in a reservoir, according to the mass flow rate of extraction, and to define the critical mass flow rate of extraction, which is the value exhausting the reservoir in an infinite time. The price evolution with time of the resource sold to the market is investigated in case of no-accumulation and no-depletion of the resources; i.e. when the resources are extracted and sold to the market at the same mass flow rate. The energy conservation equation is transformed into an energy-capital conservation equation, which allows to study the oil price evolution with time, dependent on the following parameters. The parameter PIFE, “Price Increase Factor of Extracted resource”, is the difference between the basic interest rate of the capital, e.g. inflation rate, and the mass flow rate of extraction. The parameter PIFS, “Price Increase Factor of Sold resource”, is the difference between the interest rate of the capital, e.g. prime rate, and the mass flow rate of extraction. The parameter CIPS, “Critical Initial Price of Sold resource”, depends on the initial price of the extracted resource, the interest rate of non-extracted resource, and the difference between PIFS and PIFE. The parameter CIPES, “Critical Initial Price Extreme of Sold resource”, depends on the initial price of the extracted resource, the interest rate of non-extracted resource, and PIFS. The present theory is applied to the time evolution of the oil price during the years following the economic crisis of 2008, introducing the new category of cases with a negative inflation rate, that was registered during 2009. The present theory can be applied also to the months with negative inflation rate with a reasonable fair agreement.

The present paper presents preliminary numerical solutions of the flow evolution of a two dimensional rectangular free jet. The numerical simulations in a two-dimensional domain are carried out with Open-FOAM, the open-source code, and compare the numerical results with the experimental visualizations performed in the same laboratory with the shadowgraph technique. The evolution of a two-dimensional submerged free jet is reported in the literature by the presence of two regions of flow: the potential core, where the centerline velocity maintains equal to that on the slot exit, and the turbulent or mixing region, where the centerline velocity decreases with the distance from the exit. Previous anemometric measurements, carried out in this laboratory with an air jet emerging from a rectangular channel, showed the presence of a region of flow, just outside the exit and before the potential core, where velocity and turbulence remain almost equal to those measured on the exit, and it has been called “undisturbed region of flow” because is present also in turbulent conditions. Previous and present shadowgraph visualizations show a jet which has the same height along the undisturbed region of flow and increases its height afterwards. The length of the undisturbed region depends on the Reynolds number of the flow and on the presence of turbulence promoters, e.g. metallic grids, at the exit of the slot. The undisturbed region is becoming nil with the increase of the Reynolds numbers, in agreement to the literature. The present two dimensional numerical solutions, carried out at Re numbers equal to 25,000 and 60,000 confirm the results obtained with the shadow visualizations.Copyright © 2012 by ASME