A new approach on helices in pseudo-Riemannian manifolds

In this paper, we give a definition of harmonic curvature functions in terms of V_{n} and define a new kind of slant helix which is called V_{n}-slant helix in n-dimensional pseudo-Riemannian manifold. Also, we give important characterizations about the helix.Comment: arXiv admin note: substantial text overlap with arXiv:1305.704

A new approach on helices in Euclidean n-space

In this work, we give some new characterizations for inclined curves and slant helices in n-dimensional Euclidean space E^{n}. Morever, we consider the pre-characterizations about inclined curves and slant helices and reconfigure them

Usporedba ekonomskih i tehnoloških svojstava brezovine i bukovine za proizvodnju furnirske ploče

The aim of this study was to investigate the use of birch wood, one of the most important wood species used in the plywood industry, especially in Europe, the Nordic countries, Poland, Belarus and Russia as an alternative to beech wood. For this purpose, comparison was made of their economic and technological properties. In five-ply plywood manufacturing, beech (Fagus orientalis Lipsky) and birch (Betula pendula) veneer sheets were used with melamine urea formaldehyde (MUF) and urea formaldehyde (UF) resins. Some mechanical properties such as shear strength, bending strength and modulus of elasticity of plywood panels were conducted according to EN 314-1 and EN 310, respectively. Mean mechanical strength obtained for birch plywood panels was quite above the limit values specified in the related standards. When taking into consideration the annual increment of beech and birch trees in 1 ha and the time they need to reach suitable diameters for the manufacturing of rotary cut veneers, it was calculated that birch trees provide 2.46 times more physical harvesting than beech trees.U radu je istraživana uporaba brezovine kao jedne od najvažnijih vrsta drva koja se upotrebljava kao alternativa bukovini za proizvodnju furnirskih ploča, posebice u Europi, u nordijskim zemljama, Poljskoj, Bjelorusiji i Rusiji. Za potrebe rada uspoređivana su njihova ekonomska i tehnološka svojstva. U proizvodnji furnirske ploče od pet slojeva upotrijebljeni su listovi furnira od bukovine (Fagus orientalis Lipsky) i brezovine (Betula pendula), koji su slijepljeni ljepilom na bazi melamin-urea-formaldehidnih (MUF) i urea-formaldehidnih (UF) smola. Ispitana su mehanička svojstva furnirskih ploča prema normi EN 314-1 i EN 310, i to čvrstoća na smicanje, čvrstoća na savijanje i modul elastičnosti. Dobivene srednje vrijednosti čvrstoće brezovih i bukovih furnirskih ploča bile su znatno iznad graničnih vrijednosti navedenih u normama. Kada se u obzir uzme godišnji prirast bukve i breze na 1 ha šume i vrijeme potrebno za postizanje odgovarajućih promjera za proizvodnju ljuštenih furnira, izračunano je da breza osigurava 2,46 puta više raspoložive količine za sječu od bukve

Utjecaj parametara CNC obrade na kvalitetu površine drvnih ploča koje se upotrebljavaju u industriji namještaja

The processing of wood-based panels such as plywood, particleboard and fiberboard, which are widely used in the furniture industry, with CNC (Computer Numerical Control) milling machines has been increasing recently. Even though CNC milling machines have many advantages for furniture producers, it is difficult to set process parameters to obtain the desired surface quality of the material. Therefore, it is necessary to determine the most suitable of these parameters for the surface quality of each wood-based panel. This study aimed to determine the effects of processing parameters on the surface quality of plywood, particleboard and medium density fiberboard (MDF) panels processed in CNC milling machines. Furthermore, the average surface roughness values of these panels were compared after CNC processing. Three spindle rotational frequencies (10.000, 14.000 and 18.000 rpm), three feed rates (5, 7, and 9 m/min) and two cutting tool diameters (2 and 5 mm) were selected as CNC processing parameters. To determine the surface quality of wood-based panels, the surface roughness measurements were performed according to DIN 4768 standard and three surface roughness parameters (Ra, Rmax and Rz) were determined. According to the results of this study, it can be concluded that the surface roughness values of wood-based panels decreased with increasing spindle rotational frequency and feed rate, while they increased with increasing cutting tool diameter. Among the wood-based panels used in this study, the lowest average roughness values were obtained for plywood samples.Za obradu ploča na bazi drva kao što su furnirske ploče, iverice i vlaknatice, koje imaju široku primjenu u industriji namještaja, u posljednje se vrijeme sve češće primjenjuju CNC (Computer Numerical Control) glodalice. Iako CNC glodalice imaju mnoge prednosti za proizvođače namještaja, teško je odrediti parametre procesa za postizanje željene kvalitete površine obrađivanog materijala. Stoga je potrebno odrediti najprikladnije parametre obrade za svaku vrstu ploče na bazi drva. Cilj ovog istraživanja bio je utvrditi utjecaj parametara obrade CNC glodalicama na kvalitetu površine furnirske ploče, iverice i ploče vlaknatice srednje gustoće (MDF ploče). Nadalje, uspoređene su srednje vrijednosti hrapavosti površine tih ploča nakon CNC obrade. Kao parametri CNC obrade odabrane su tri frekvencije vrtnje vretena (10 000, 14 000 i 18 000 okr./min), tri posmične brzine (5, 7 i 9 m/min) te dva promjera reznog alata (2 i 5 mm). Za određivanje kvalitete površine ploča na bazi drva provedena su mjerenja hrapavosti površine prema normi DIN 4768, a hrapavost je iskazana trima parametrima hrapavosti površine (Ra, Rmax i Rz). Prema rezultatima ovog istraživanja može se zaključiti da su se vrijednosti hrapavosti površine ploča na bazi drva smanjivale s povećanjem frekvencije vrtnje vretena i posmične brzine, dok su se povećavale s povećanjem promjera reznog alata. Među pločama na bazi drva na kojima je provedeno ovo istraživanje najniže srednje vrijednosti hrapavosti dobivene su za uzorke furnirske ploče

Factors Predicting Febrile Urinary Tract Infection After Ureterorenoscopic Lithotripsy in Pediatric Patients

Introduction: There is no study investigating the factors predicting postoperative febrile urinary tract infection (fUTI) in pediatric patients. We aimed to determine the factors predicting postoperative fUTI in pediatric patients who underwent ureterorenoscopic lithotripsy (URS-L). Methods: Pediatric patients who underwent URS-L due to ureter or kidney stones in our clinic between 2012 and 2019 were analyzed retrospectively. The demographic data, stone characteristics, intraoperative and postoperative data of those with and without postoperative fUTI were compared. Univariable and multivariable binary logistic regression analysis was performed to determine predictors of fUTI. Results: A total of 136 patients were included in the study. Postoperative fUTI developed in 17 patients (12.5%). History of stone surgery, history of UTI, presence of nephrostomy/D-J stent, type of surgery, operation time, length of stay, and presence of complication except fUTI were found to be significantly different in the fUTI group. In the univariate analysis, history of stone surgery, history of UTI, presence of nephrostomy/D-J stent, type of surgery, operation time, and presence of complication except fUTI were determined as factors predicting fUTI. In multivariate analysis, only the history of UTI was identified as an independent predictive factor. Conclusion: In pediatric patients, infectious complications constitute the majority of complications after URS-L. History of UTI is the only independent factor that predicts postoperative fUTI after URS-L

Comparison of the Mechanical Properties of Plywood Produced from Native Beech Logs and Birch Imported from Countries in the Coast to the Black Sea

lywood is usually used in the production of some common species such as beech, alder, poplar, spruce, pine, okume, tetra, ozigo and other tropic species. Because of the beech tree is often used species in ourcountry brings the high cost of raw material supply. Therefore, the use of different tree species, emphasizes the necessity to manufacture plywood. In this study, birch wood, an important tree species which is particularly used in Europe, the Baltic States, Poland, Belarus and Russia in plywood industry was investigated compared with beech wood. For this aim; the plywood panels (beech, birch and birch-beech) produced from the veneers obtained from birch imported in Ukraine and native beech logs using urea formaldehyde and melamine urea formaldehyde adhesives were compared. Shear strength and bending strength of plywood panels were determined according to TS EN 314-1 and TS EN 310. As a result of the study, the mechanical properties of the plywood panels produced from birch veneers gave close close values according to beech plywood. It was seen that it met the required standard values according to the place of use

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat