843 research outputs found

    POMIAR STRUMIENIA MIESZANINY GAZ-CIECZ Z WYKORZYSTANIEM KRYZY STANDARDOWEJ I KRYZY SZCZELINOWEJ

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    The differential pressure of gas measurement is very often used in industrial measurements. During the gas flow, liquid condensation often occurs. The result is that when measuring a gas flow, the gas-liquid mixture is essentially measured. Errors in the indications of measuring instruments are starting to appear due to a change in the properties of the continuous phase, which is gas. In addition, the appearance of liquid droplets leads to flow disturbances and pressure pulsations. Therefore, new methods and tools for measuring the flow of gas-liquid mixture are being sought. The work involves the use of slotted orifices for measuring gas-liquid mixtures. An analysis of the influence of the slotted orifice geometry on the measurement of the biphasic mixture stream was carried out. Standard orifice and three slotted orifices of various designs. The experiment included measuring the air flow with a small amount of water dispersed in the form of drops.Pomiar gazu metodÄ… zwężkowÄ… jest bardzo czÄ™sto stosowany w pomiarach przemysÅ‚owych. Podczas przepÅ‚ywu gazu bardzo czÄ™sto dochodzi do wykroplenia siÄ™ cieczy. Powoduje to, że mierzÄ…c przepÅ‚yw gazu w zasadzie mierzy siÄ™ mieszaninÄ™ gaz – ciecz. ZaczynajÄ… pojawiać siÄ™ bÅ‚Ä™dy wskazaÅ„ przyrzÄ…dów pomiarowych wynikajÄ…cych ze zmiany wÅ‚aÅ›ciwoÅ›ci fazy ciÄ…gÅ‚ej, którÄ… jest gaz. Dodatkowo pojawienie siÄ™ kropel cieczy prowadzi do powstawania zaburzeÅ„ przepÅ‚ywu i pulsacji ciÅ›nienia. W zwiÄ…zku z tym  poszukuje siÄ™ nowych metod i narzÄ™dzi do pomiaru przepÅ‚ywu mieszaniny gaz-ciecz. Praca obejmuje zastosowanie kryz szczelinowych do pomiaru mieszanin gaz-ciecz. Przeprowadzono analizÄ™ wpÅ‚ywu geometrii kryzy szczelinowej na pomiar strumienia mieszaniny dwufazowej. Badaniom kryzÄ™ standardowÄ… oraz trzy kryzy szczelinowe o różnych konstrukcjach. Eksperyment obejmowaÅ‚ pomiar przepÅ‚ywu powietrza z niewielkÄ… iloÅ›ciÄ… wody rozproszonej w postaci kropel

    Hydrogen adsorption on Pd(133) surface

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    In this study used is an approach based on measurements of the total energy distribution (TED) of field emitted electrons in order to examine the properties of Pd (133) from the aspect of both hydrogen adsorption and surface hydrides formation. The most favourable sites offered to a hydrogen atom to be adsorbed have been indicated and an attempt to describe the peaks of the enhancement factor R spectrum to the specific adsorption sites has also been made.Comment: to be submitted to the Centr. Eur. J. Phy

    The Thebesian valve and its significance for electrophysiologists

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    Background: Invasive cardiac procedures, such as arrhythmia ablation, cardiac resynchronisation therapy, percutaneous mitral annuloplasty and retrograde cardioplegia delivery require cannulation of the coronary sinus (CS). Detailed knowledge of the CS ostium region, including recognition of the presence of the Thebesian valve which sometimes covers the sinus, is a key to successfully carryout such procedures.Materials and methods: In the present study, 160 autopsied human hearts from both sexes were examined for the presence of the Thebesian valve. If identified, the histological structure of the valve was studied.Results: Five types of the CS valve were distinguished; all of them presented with a typical histological structure with the exception of the cord-like type, in which cells were similar to those of the conduction system of the heart.Conclusions: Proper identification of the CS valve and analysis of its size and histological features could have important implications for electrophysiologists

    Endplate calcification and cervical intervertebral disc degeneration: the role of endplate marrow contact channel occlusion

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    Background: The aim of this study was to determine the fundamental relationships between cervical intervertebral disc (IVD) degeneration, endplate calcification, and the patency of endplate marrow contact channels (MCC). Materials and methods: Sixty cervical IVDs were excised from 30 human cadavers. After sectioning the specimens underwent micro computed tomography (microCT) — from all images the number, calibre, diameter and distribution of endplate openings were measured using ImageJ. Next, the specimens were scored for macroscopic degeneration (Thompson’s classification), and subsequently underwent histological analysis for both IVD and endplate degeneration (Boos’s classification) and calcification. Results: The study group comprised 30 female and 30 male IVDs (mean age ± SD: 51.4 ± 19.5). Specimen’s age, macroscopic and microscopic degeneration correlated negatively with the number of MCCs (r = –0.33–(–0.95); p < 0.0001), apart from the MCCs > 300 μm in diameter (r = 0.66–0.79; p < 0.0001). The negative relationship was strongest for the MCCs 10–50 μm in diameter. Conclusions: There is a strong negative correlation between the number of endplate MCCs, and both macroscopic and microscopic cervical IVD and endplate degeneration. This could further support the thesis that endplate calcification, through the occlusion of MCCs, leads to a fall in nutrient transport to the IVD, and subsequently causes its degeneration

    Extra- and intracerebral course of the recurrent artery of Heubner

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    Background: The aim of the current study was to analyse the extra- and intracerebral course of the recurrent artery of Heubner (RAH) to provide detailed information for neurosurgeons operating in this area.Materials and methods: The material for this study was obtained from cadavers (ages 31–75 years) during routine autopsies. A total of 70 human brains (39 male and 31 female) were examined. The material was collected not later than 48 h post-mortem. People who died due to neurological disorders were not includedinto the study. Right after dissection the arteries were perfused with either acrylicpaint emulsion, polyvinyl chloride or Mercox CL-2R resin, through the Circle ofWillis or electively through the RAH. The obtained material was analysed usinga stereoscopic light microscope, magnification 2–40´.Results: The RAH was present in 138 hemispheres with a mean of 1.99 RAH per hemisphere (275 RAH in total). The mean RAH length was 25.2 mm and the mean RAH diameter, in its place of origin, was 1 mm. In 168 (61%) cases the RAH ran superiorly, in 88 (32%) cases anteriorly, in 11 (4%) cases inferiorly and in 8 (3%) cases posteriorlyto the A1 segment. In 70.2% of the cases the course of the RAH was parallel to theanterior communicating artery A1 segment, and in 29.8% of the cases the RAH archedtowards the olfactory tract. As the extracerebral course of the RAH was always tortuous,its length was 1 to 5 times the distance between its place of origin and the most lateralpoint of anterior perforated substance (APS) penetration. The intracerebral course ofthe RAH was almost always univectorial — towards the head of the caudate nucleus.The course of RAH branches depended on their number. When the number of RAH sand their branches was low, they separated immediately after penetrating the APS andformed multiple small branches. When the number of RAHs and branches was high,post-APS branching was less frequent and occurred in distal segments.Conclusions: The origin and course of the RAH is highly variable. The RAH, in itsextra- and intracerebral course, may join with the middle group of the lenticulostriatearteries or directly with the middle cerebral artery. This artery should beroutinely identified during anterior communicating artery aneurysm clipping toprevent postoperative neurological deficits

    The presence of B7-H4+ macrophages and CD25+CD4+ and FOXP3+ regulatory T cells in the microenvironment of nasal polyps - a preliminary report.

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    The nasal polyp (NP) seems to represent the end-stage of longstanding inflammation in patients with chronic rhinosinusitis. The aim of our study has been to evaluate the presence of two regulatory cell populations in the microenvironment of NP: CD4+CD25high Foxp3+ (Treg) cells and B7-H4-expressing macrophages. Treg cells are actively able to inhibit T lymphocytes, while the population of B7-H4-expressing macrophages has recently been described as characterized by a regulatory function similar to that of Treg cells. For our study, we evaluated 14 NP tissue samples. The samples were divided into two main groups, eosinophilic (NP) and lymphocytic (NP), according to the predominant type of immune cell infiltration. The presence of Treg cells and B7-H4 positive macrophages in the samples was analyzed by FACS. Treg cells and B7-H4-expressing macrophages were identified in all the examined nasal polyps. The percentages of both Treg cells and of B7H4 positive cells found in the eosinophilic nasal polyps were higher than those found in the lymphocytic nasal polyps. Treg cells and B7H4+ macrophage subpopulations were present in the NP microenvironment and the alterations in their percentages were related to a distinct pattern of immune cell infiltration

    COST 733 - WG4: Applications of weather type classification

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    The main objective of the COST Action 733 is to achieve a general numerical method for assessing, comparing and classifying typical weather situations in the European regions. To accomplish this goal, different workgroups are established, each with their specific aims: WG1: Existing methods and applications (finished); WG2: Implementation and development of weather types classification methods; WG3: Comparison of selected weather types classifications; WG4: Testing methods for various applications. The main task of Workgroup 4 (WG4) in COST 733 implies the testing of the selected weather type methods for various classifications. In more detail, WG4 focuses on the following topics:• Selection of dedicated applications (using results from WG1), • Performance of the selected applications using available weather types provided by WG2, • Intercomparison of the application results as a results of different methods • Final assessment of the results and uncertainties, • Presentation and release of results to the other WGs and external interested • Recommend specifications for a new (common) method WG2 Introduction In order to address these specific aims, various applications are selected and WG4 is divided in subgroups accordingly: 1.Air quality 2. Hydrology (& Climatological mapping) 3. Forest fires 4. Climate change and variability 5. Risks and hazards Simultaneously, the special attention is paid to the several wide topics concerning some other COST Actions such as: phenology (COST725), biometeorology (COST730), agriculture (COST 734) and mesoscale modelling and air pollution (COST728). Sub-groups are established to find advantages and disadvantages of different classification methods for different applications. Focus is given to data requirements, spatial and temporal scale, domain area, specifi

    Extralaryngeal branching of the recurrent laryngeal nerve : a meta-analysis of 28,387 nerves

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    INTRODUCTION: The recurrent laryngeal nerves (RLN) are branches of the vagus nerve that go on to innervate most of the intrinsic muscles of the larynx. Historically, the RLN has been considered to branch after it enters the larynx, but numerous studies have demonstrated that it often branches before. The wide variability of this extralaryngeal branching (ELB) has significant implications for the risk of iatrogenic injury. We aimed to assess the anatomical characteristics of ELB comprehensively. METHODS: Articles on the ELB of the RLN were identified by a comprehensive database search. Relevant data were extracted and pooled into a meta-analysis of the prevalence of branching, branching pattern, distance of ELB point from the larynx, and presence of positive motor signals in anterior and posterior ELB branches. RESULTS: A total of 69 articles (n = 28,387 nerves) from both intraoperative and cadaveric modalities were included in the meta-analysis. The overall pooled prevalence of ELB was 60.0 % (95 % CI 52.0–67.7). Cadaveric and intraoperative subgroups differed with prevalence rates of 73.3 % (95 % CI 61.0–84.0) and 39.2 % (95 % CI 29.0–49.9), respectively. Cadavers most often presented with a ELB pattern of bifurcation, with a prevalence of 61.1 %, followed by no branching at 23.4 %. Branching of the RLN occurred most often at a distance of 1–2 cm (74.8 % of cases) prior to entering the larynx. A positive motor signal was most often noted in anterior RLN branches (99.9 %) but only in 1.5 % of posterior branches. CONCLUSIONS: The anatomy of the RLN is highly variable, and ELB is likely to have been underreported in intraoperative studies. Because of its high likelihood, the possibility of ELB needs to be assessed in patients to prevent iatrogenic injury and long-term postoperative complications. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00423-016-1455-7) contains supplementary material, which is available to authorized users

    The reliability of the Tracheoesophageal Groove and the Ligament of Berry as landmarks for identifying the Recurrent Laryngeal Nerve : a cadaveric study and meta-analysis

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    Purpose. The aim of this meta-analysis was to provide a comprehensive evidence-based assessment, supplemented by cadaveric dissections, of the value of using the Ligament of Berry and Tracheoesophageal Groove as anatomical landmarks for identifying the Recurrent Laryngeal Nerve. Methods. Seven major databases were searched to identify studies for inclusion. Eligibility was judged by two reviewers. Suitable studies were identified and extracted. MetaXL was used for analysis. All pooled prevalence rates were calculated using a random effects model. Heterogeneity among included studies was assessed using the Chi2 test and the I2 statistic. Results. Sixteen studies (n=2,470 nerves), including original cadaveric data, were analyzed for the BL/RLN relationship. The RLN was most often located superficial to the BL with a pooled prevalence estimate of 78.2% of nerves, followed by deep to the BL in 14.8%. Twenty-three studies (n=5,970 nerves) examined the RLN/TEG relationship. The RLN was located inside the TEG in 63.7% (95% CI: 55.3–77.7) of sides. Conclusions. Both the BL and TEG are landmarks that can help surgeons provide patients with complication-free procedures. Our analysis showed that the BL is a more consistent anatomical landmark than the TEG, but it is necessary to use both to prevent iatrogenic RLN injuries during thyroidectomies

    The problem of series of days without rainfall in a view of efficiency of agricultural output under climate change

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    Modelling future is key issue in studying CC impacts on agriculture across disciplines and scales. Improving models basing on empirical data coming from diverse micro regions let obtain synergic effects important in shaping food security. Especially, rainfall distribution is most important factor determining agricultural output.The amount of cereal yield depends on an occurrence of long series of days without rain during a growing season. Based on statistical analysis of daily totals it was found that in Central Poland the length of series of days without rainfall during growing season is 40 days. Statistical analysis was done for years 1971-2015. The data allowed finding empirical probability distribution of a length of the series. Average value of the length of series is 4.31 while SD is 4.41. Values of parameters of gamma distribution estimated by the likelihood method are: α=0.9542, β=4.5150. Value of the parameter α (shape parameter) suggests that distribution of the length of series is similar to exponential distribution.Goodness of fit test with gamma distribution was carried out using λ-Kolmogorov and χ2-Pearson tests. Both prove high conformity between empirical and gamma distribution. Based on assumption that gamma distribution can be accepted as distribution of the length of rainless series, further is determined distribution of the length of the longest series in n-element random sample. On the theory of distributions of asymptotic order statistics it is known that the random variable T(n) with appropriate normalization has asymptotic double exponential distribution. Based on that one can conclude that probability to occur 30-day rainless series or longer equals approx. to 0.48. This is useful in forecasting agricultural output depended on rainfall distribution
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