Turbulence suppression by cardiac-cycle-inspired driving of pipe flow.

Flows through pipes and channels are, in practice, almost always turbulent, and the multiscale eddying motion is responsible for a major part of the encountered friction losses and pumping costs1. Conversely, for pulsatile flows, in particular for aortic blood flow, turbulence levels remain low despite relatively large peak velocities. For aortic blood flow, high turbulence levels are intolerable as they would damage the shear-sensitive endothelial cell layer2-5. Here we show that turbulence in ordinary pipe flow is diminished if the flow is driven in a pulsatile mode that incorporates all the key features of the cardiac waveform. At Reynolds numbers comparable to those of aortic blood flow, turbulence is largely inhibited, whereas at much higher speeds, the turbulent drag is reduced by more than 25%. This specific operation mode is more efficient when compared with steady driving, which is the present situation for virtually all fluid transport processes ranging from heating circuits to water, gas and oil pipelines.

Ozone as an alternative decontamination process for N95 facemask and biosafety gowns.

COVID-19 pandemic created a global shortage of medical protective equipment. Here, we considered ozone (O3) a disinfectant alternative due to its potent oxidative activity against biological macromolecules. The O3 decontamination assays were done using SARS-CoV-2 obtained from patients to produce artificial contamination of N95 masks and biosecurity gowns. The quantification of SARS-CoV-2 was performed before and after exposing the samples to different ozone gas concentrations for times between 5 and 30 min. Viral loads as a function of the O3 exposure time were estimated from the data obtained by the RT-PCR technique. The genetic material of the virus was no longer detected for any tested concentrations after 15 min of O3 exposure, which means a disinfection Concentration-Time above 144 ppm min. Vibrational spectroscopies were used to follow the modifications of the polymeric fibers after the O3 treatment. The results indicate that the N95 masks could be safely reused after decontamination with treatments of 15 min at the established O3 doses for a maximum of 6 cycles.

Characteristics of Acral Lentiginous Melanoma According to Location in Stress- or Non-Stress-Bearing Areas: A Retrospective Study of 95 Patients. / Características del melanoma lentiginoso acral según su relación con la presión. Estudio retrospectivo de 95 pacientes.

BACKGROUND AND OBJECTIVE: Acral lentiginous melanoma (ALM) arises in areas that are not generally exposed to UV radiation. Chronic trauma has been hypothesized to play a role in the development of this tumor. The aim of this study was to analyze the association between the presence and characteristics of ALM and location in stress- and non-stress-bearing areas. MATERIAL AND METHODS: Observational, descriptive analysis. For 95 patients with ALM evaluated at Fundación Clínica Vida in Medellin, Colombia between January 2016 and August 2020 we collected demographic, histologic and clinical variables and assigned the patients to 2 groups depending on whether their tumor was located in a stress-bearing area or not. RESULTS: Ninety-five patients (36 men and 59 women) with a median age of 59 years were studied. ALMs were more common in stress-bearing areas than in non-stress-bearing areas (58 [61%] vs. 17 [17.8%]). A history of direct trauma at the site of the tumor was reported in 18.9% of the cases (p = .025) and was most common in patients with nail lesions. Invasive ALMs in stress-bearing areas had a greater Breslow thickness (p = .006) and higher ulceration rates than those in non-stress-bearing areas (p = .018). CONCLUSIONS: ALM on both the feet and hands is more common in stress-bearing areas. Our findings support the hypothesis that mechanical stress may have a pathogenic role in ALM.

Suppression of cooling by strong magnetic fields in white dwarf stars.

Isolated cool white dwarf stars more often have strong magnetic fields than young, hotter white dwarfs, which has been a puzzle because magnetic fields are expected to decay with time but a cool surface suggests that the star is old. In addition, some white dwarfs with strong fields vary in brightness as they rotate, which has been variously attributed to surface brightness inhomogeneities similar to sunspots, chemical inhomogeneities and other magneto-optical effects. Here we describe optical observations of the brightness and magnetic field of the cool white dwarf WD 1953-011 taken over about eight years, and the results of an analysis of its surface temperature and magnetic field distribution. We find that the magnetic field suppresses atmospheric convection, leading to dark spots in the most magnetized areas. We also find that strong fields are sufficient to suppress convection over the entire surface in cool magnetic white dwarfs, which inhibits their cooling evolution relative to weakly magnetic and non-magnetic white dwarfs, making them appear younger than they truly are. This explains the long-standing mystery of why magnetic fields are more common amongst cool white dwarfs, and implies that the currently accepted ages of strongly magnetic white dwarfs are systematically too young.

Epidemiological behavior and current forecast of syphilis in Mexico: increase in male population.

OBJECTIVES: Even when new cases of syphilis are notifiable since 1944, the Mexican National Epidemiological Surveillance System lacks information on the changes of the rate of case reports considering the geographic and demographic variables. Therefore, it is necessary to have evidence, with particular attention to the study of the epidemiological behavior by the identification of risk factors and groups. The objective of this study was to analyze the epidemiology, geographical distribution, and forecast of syphilis in Mexico. STUDY DESIGN: The design of the study was a secondary research of epidemiological databases. METHODS: A retrospective analysis of the national surveillance data (2007-2017) of acquired and congenital syphilis (CS) issued by the General Directorate of Epidemiology was performed. RESULTS: Of all cases, 34,998 and 1030 cases were reported for acquired syphilis (AS) and CS , respectively, reflecting an increasing trend in the whole country for both diseases. Cases and incidence of AS per year showed that, male gender presented an increase in reproductive age. Distribution of the rate of case reports is mostly commanded by the states in the extreme north (Gulf of California and northern Gulf of Mexico) and south (Gulf of southern Mexico and the Caribbean Sea). Likewise, the Seasonal Autoregressive Integrated Moving Average model was selected as the best-fit model for the forecast analysis. This model was used to forecast AS cases during 2018-2019. AS may have a slight fluctuation (on the rise) during the following 24 months. CONCLUSIONS: These findings underscore the importance of intensifying, as well as expanding screening and treatment in adult population, including men, who are not routinely benefiting from maternal and reproductive service-based syphilis screening and treatment.

Systemic bevacizumab for the treatment of chronic bleeding in hereditary haemorrhagic telangiectasia.

BACKGROUND: Hereditary haemorrhagic telangiectasia (HHT) is a rare hereditary multisystem vascular disorder causing visceral arteriovenous malformations and mucocutaneous bleeding. Chronic gastrointestinal bleeding and epistaxis often produce profound anaemia refractory to conventional treatment. Bevacizumab, an anti-vascular endothelial growth factor monoclonal antibody, may be effective in treatment of bleeding in HHT. METHODS: All HHT patients treated with systemic bevacizumab for chronic bleeding were selected for retrospective analysis. Data collected included demographics, baseline HHT characteristics, epistaxis grade, surgical interventions, bevacizumab dosing, adverse events, haemoglobin, red cell transfusions, intravenous iron infusions, and other anaemia and/or bleeding-directed therapies. RESULTS: Thirteen HHT patients were treated with bevacizumab for a median of 13.9 (range 4.9-30.1) months. Compared with pretreatment values, bevacizumab treatment increased the mean haemoglobin by 4.0 g dL-1 (95% CI, 2.6-5.3 g dL-1 ) [mean (95% CI) haemoglobin 8.5 (7.8, 9.9) g dL-1 vs. 12.5 (11.2, 13.7) g dL-1 , P < 0.001)], reduced red cell units transfused by 92% [median of 6 (range 0-59) units vs. 0 (range 0-15) units, P = 0.004] and reduced quantity of iron infused by 73% [mean (95% CI) 462 (257, 668) mg month-1 vs. 126 (75, 178) mg month-1 , P = 0.002]. Epistaxis control was achieved in 85% with bevacizumab versus 0% before treatment (P < 0.001). No patient required nasal or GI procedures during the maintenance period. Two patients (15%) developed grade 3 hypertension requiring medical management. CONCLUSION: Systemic bevacizumab was highly effective to treat chronic bleeding in HHT. Further study is needed to confirm the magnitude of benefit and further define optimal dosing, treatment duration and long-term safety.

Evolution of incidence and geographical distribution of Chagas disease in Mexico during a decade (2007-2016).

Chagas disease, whose aetiological agent is the protozoan Trypanosoma cruzi, mainly occurs in Latin America. In order to know the epidemiology and the geographical distribution of this disease in Mexico, the present work analyses the national surveillance data (10 years) for Chagas disease issued by the General Directorate of Epidemiology (GDE). An ecological analysis of Chagas disease (2007-2016) was performed in the annual reports issued by the GDE in Mexico. The cases and incidence were classified by year, state, age group, gender and seasons. A national distribution map showing Chagas disease incidence was generated. An increase of new cases was identified throughout the country (rates from 0.37 to 0.81 per 100 000 inhabitants). Of the total cases accumulated (7388), the major cases were attributed to the states of Veracruz, Chiapas, Quintana Roo, Oaxaca, Morelos and Yucatán. The analysis per age groups and gender revealed that, in most age groups, the incidence was higher in the male population. The most number of cases was identified in spring and summer; a direct relationship between the environmental temperature increase and the number of new cases was identified. The analysis showed that the rate of Chagas disease increased presumably due to state programmes; the search for new cases has expanded and we speculate that the disease is associated with occupational activities. These results summarise and recall how important it is to implement the monitoring of Chagas disease mainly in south states of the Mexican Republic in order to implement strategies to control this disease.

Genetic basis of octanoic acid resistance in Drosophila sechellia: functional analysis of a fine-mapped region.

Drosophila sechellia is a species of fruit fly endemic to the Seychelles islands. Unlike its generalist sister species, D. sechellia has evolved to be a specialist on the host plant Morinda citrifolia. This specialization is interesting because the plant's fruit contains secondary defence compounds, primarily octanoic acid (OA), that are lethal to most other Drosophilids. Although ecological and behavioural adaptations to this toxic fruit are known, the genetic basis for evolutionary changes in OA resistance is not. Prior work showed that a genomic region on chromosome 3R containing 18 genes has the greatest contribution to differences in OA resistance between D. sechellia and D. simulans. To determine which gene(s) in this region might be involved in the evolutionary change in OA resistance, we knocked down expression of each gene in this region in D. melanogaster with RNA interference (RNAi) (i) ubiquitously throughout development, (ii) during only the adult stage and (iii) within specific tissues. We identified three neighbouring genes in the Osiris family, Osiris 6 (Osi6), Osi7 and Osi8, that led to decreased OA resistance when ubiquitously knocked down. Tissue-specific RNAi, however, showed that decreasing expression of Osi6 and Osi7 specifically in the fat body and/or salivary glands increased OA resistance. Gene expression analyses of Osi6 and Osi7 revealed that while standing levels of expression are higher in D. sechellia, Osi6 expression is significantly downregulated in salivary glands in response to OA exposure, suggesting that evolved tissue-specific environmental plasticity of Osi6 expression may be responsible for OA resistance in D. sechellia.

Histological differences in the adherence of connective tissue to laser-treated abutments and standard abutments for dental implants. An experimental pilot study in humans.

BACKGROUND: The goal of the current study is to assess the difference in connective tissue adherence to laser microtextured versus machined titanium abutments. MATERIAL AND METHODS: Six patients were selected and each of them received 2 implants, one combined with a laser treated abutment and one with a machined abutment. After three months, the abutments were retrieved together with their surrounding gingival tissue for histological analysis. Qualitative and quantitative evaluation of microscopical images was performed to assess the presence or absence of adherence between the soft tissues and the abutment, and the percentage of soft tissue adhered to the two different surfaces. RESULTS: Intimate adherence between connective tissue and the laser treated abutments, while on machined abutments no adherence was detected. A significant difference was found in the percentage of surface in contact with soft tissue between both implant abutments p=0.03. CONCLUSIONS: Within the limitation of the current study, it can be concluded that connective tissues show enhanced adherence to microtextured abutments compared to machined abutments.

Optimization of the surface properties of nanostructured Ni-W alloys on steel by a mixed silane layer.

Ni-W nanostructured coatings electrodeposited on steel by galvanostatic pulses were functionalized by tetraethoxysilane (TEOS) and octadecyltrichlorosilane (OTS) in a two-step procedure. A silica-rich layer is formed by the reaction of TEOS with the metal coating surface oxides, which allows a further reaction with OTS forming a hydrocarbon-silica outer network. This mixed silane layer provides hydrophobicity and improves the corrosion behavior of the Ni-W surface coatings without modifying their excellent mechanical properties.

Early stages of bone fracture healing: formation of a fibrin-collagen scaffold in the fracture hematoma.

This work is concerned with the sequence of events taking place during the first stages of bone fracture healing, from bone breakup until the formation of early fibrous callus (EFC). The latter provides a scaffold over which subsequent remodeling processes will eventually result in successful bone repair. Specifically, some mathematical models are proposed to estimate the time required for (1) the formation immediately after fracture of a fibrin clot, described in terms of a phase transition in a polymerization process, and (2) the onset of EFC which is produced when fibroblasts arising from differentiation of chemotactically recruited mesenchymal stem cells remodel a previous fibrin clot by releasing a collagen matrix over it. An attempt has been made to keep models as simple as possible, so that a explicit dependence of the estimates obtained on relevant biochemical parameters involved is obtained.

TIMEKEEPING IN THE AMERICAS.

Time and its measurement belong to the most fundamental core of physics, and many scientific and technological advances are directly or indirectly related to time measurements. Timekeeping is essential to everyday life, and thus is the most measured physical quantity in modern societies. Time can also be measured with less uncertainty and more resolution than any other physical quantity. The measurement of time is of the utmost importance for many applications, including: global navigation satellite systems, communications networks, electric power generation, astronomy, electronic commerce, and national defense and security. This paper discusses how time is kept, coordinated, and disseminated in the Americas.

Determination of reference values for serum folate and vitamin B12 using three different immunoassays: is it worth making an effort to produce them in our laboratory?

BACKGROUND: Despite being a widely studied concept, the reference interval is the most widely used medical decision-making tool. As such, it is vital that these limits are correctly established and regularly reviewed in the clinical laboratory. METHODS: The reference population comprised 315 healthy individuals selected a priori from Bizkaia province. Blood and serum samples were sent for subsequent assay of vitamin B12 and folate using three immunochemical methods. Reference values were calculated using non-parametric methods. RESULTS: The reference values for serum vitamin B12 and folate were almost identical to those obtained previously using the same methods. Use of new reference values led to an increase in the kappa value despite the low agreement in the case of vitamin B12 (0.4 - 0.62). However, precision obtained for vitamin B12 (94.48 - 96.55%) and folate (95.77 - 97.18%) was very high. The intraclass correlation coefficient ranged from 0.723 to 0.894. Furthermore, a Passing-Bablok regression analysis gave acceptable correlation coefficients of 0.75 - 0.94 for vitamin B12 and 0.92 - 0.95 for folate. CONCLUSIONS: Vitamin B12 and folate deficiencies are currently being over-diagnosed leading to an increase in the number of unnecessary consultations. The main conclusion that can be drawn from our study has resulted in a change in reference values in our laboratory, with a subsequent increase in our ability to accurately detect possible deficiencies. Furthermore, as this study involved all methods currently in use in the Basque healthcare network, its conclusions can be extrapolated to the whole population covered by Osakidetza, thereby improving the rational use of healthcare funding.

Diets rich in starch increase the posthepatic availability of amino acids in dairy cows fed diets at low and normal protein levels.

Five mid-lactation multicatheterized Jersey cows were used in a 4×4 Latin square design to investigate whether the increase in milk N yield associated with diets rich in starch versus fiber could originate from changes in the splanchnic AA metabolism and if these changes depended upon the dietary crude protein (CP) content. Four isoenergetic diets were formulated to provide 2 different carbohydrate compositions [diets rich in starch (350g of starch and 310g of neutral detergent fiber/kg of dry matter) versus rich in fiber (45g of starch and 460g of neutral detergent fiber/kg of dry matter)] crossed by 2 different CP contents (12.0 vs. 16.5% CP). At the end of each treatment period, 6 hourly blood samples were collected from the portal and hepatic veins as well as the mesenteric artery to determine net nutrient fluxes across the portal-drained viscera (PDV), liver, and total splanchnic tissues. Dry matter and calculated energy intake as well as total absorbed energy were similar across treatments. However, the net portal appearance (NPA) of acetate, total volatile fatty acids, and ß-hydroxybutyrate were higher with diets rich in fiber versus starch, whereas that of oxygen, glucose, butyrate, and insulin were lower. Concomitant to these changes, the percentage of N intake recovered as total AA (TAA) in the portal vein was lower for diets rich in fiber versus starch (42.3 vs. 51.4%, respectively), without, however, any difference observed in the NPA of the main AA used as energy fuels by the PDV (Glu, Gln, and Asp). Despite a higher NPA of TAA with starch versus fiber diets, no differences in the net hepatic flux of TAA, essential and nonessential AA were observed, resulting in a higher (+22%) net splanchnic release of AA and, hence, a greater (+7%) milk N yield. The net hepatic flux and hepatic fractional removal of none of the individual AA was affected as the main carbohydrate changed from fiber to starch, except for Gly and Lys, which were higher for the latter. After correcting for differences in NPA of TAA, the net hepatic uptake of TAA tended to be lower with starch versus fiber diets. The higher transfer of N from feed to milk with diets rich in starch is not the consequence of a direct sparing AA effect of glucogenic diets but rather the result of lower energy requirements by the PDV along with a higher microbial N flow to the duodenum. A better AA use by peripheral tissues with starch versus fiber diets was also hypothesized but more studies are warranted to clarify this issue.

Accuracy of working length measurement: electronic apex locator versus cone-beam computed tomography.

AIM: To compare the accuracy of working length (WL) determination using the Raypex 6(®) electronic apex locator and cone-beam computed tomography (CBCT). METHODOLOGY: A total of 150 extracted human teeth were decoronated and randomly assigned to five groups (n = 30). WL was measured with the Raypex 6(®) at both the 'constriction' and the 'apex' marks under dry conditions (group 1) or with 2.5% NaOCl, distilled water or Ultracain(®) (groups 2-4). The radiological WL (group 5) was calculated from bucco-lingual and mesio-distal CBCT sections. Differences between electronic, CBCT measurements and actual length (AL) were calculated. Positive and negative values, respectively, indicate measurements falling short or long of AL. Two-way anova and the Bonferroni and Welch tests were used to compare mean differences amongst groups. The chi-squared and Fisher's exact tests were used to compare percentages of precise, ±0.5 and ±1.0 mm of the AL measurements amongst the experimental groups. Statistical analysis was performed at α = 0.05. RESULTS: Mean differences with respect to AL ranged from 0.26 to -0.36 mm and from 0.05 to 0.18 mm, respectively, for the electronic measurements at the 'constriction' mark and 'apex' mark. CBCT measurements were an average of 0.59 mm shorter than AL. Percentages of electronic measurements falling within ±0.5 mm of the corresponding AL referred to the 'apex' mark were greater than at the 'constriction' mark, but the differences were only significant in group 4 (with Ultracain(®) ). Percentages of CBCT measurements falling within ±0.5 mm of AL (46.7%) were significantly lower than electronic measurements, regardless of the condition of the root canal. In 30-38.5% of the measurements taken at the 'apex' mark and in 3.4-13.3% of those at the 'constriction' mark, the file tip extended beyond the foramen. CONCLUSIONS: Electronic measurements were more reliable than CBCT scans for WL determination. The Raypex 6(®) was more accurate in locating the major foramen than the apical constriction under the experimental set-up.

[Accreditation process of pediatric healthcare professionals in Chile]. / El proceso de acreditación de Especialistas en Pediatría en Chile.

In Chile since 1984, the Autonomous Corporation for Certification of Medical Specialties (CONACEM) has certified 12,294 medical specialists. The Pediatrics discipline began its certification processes in 1984; it had certified 1,329 specialists by December, 2012. There are three possible ways to get certified: a) to have passed the Training Graduate Degree Program, taken by 57% of the applicants; b) to meet the requirements for Training in Practice for 5 years, achieved by 39% of applicants; c) to have been trained oversees according to validated programs. There are 11 accredited 3-year long university programs, which take place in Santiago and Provinces with a total annual capacity of 96 students. With the exception of doctors approved by accredited medical university programs, the rest of the applicants must pass a practical examination. A written examination has been added since 2002, whose approval is required to take the practical examination, which has proven to have good discrimination (22% average rejection in 11 years). The certifications granted today are good for 10 years and recertification is good for 7 years. The expiration of the certification process is related to recertification. This review discusses the reasons behind it and discusses the requirements and a table of credits to complete. Current legislation requires the action of at least one certification body, a condition that has been legally and uniquely granted by the Ministry of Health to CONACEM since 2/11/2014.

Multimodal and retro-mode imaging in sclerochoroidal calcification: A case report.

We present a case report on sclerochoroidal calcification (SCC), a rare condition involving calcium pyrophosphate deposits in the posterior pole of the eye in a 70-year-old patient. We provide an account of the clinical presentation and its appearance in multimodal images, using color fundus photography, swept-source optical coherence tomography (SS-OCT), ocular ultrasound, and the novel retro-mode imaging (RMI) technique. Visual acuity was 20/25 in the right eye (OD) and 20/20 in the left eye (OS). Color fundus photography revealed yellowish deposits located in the upper temporal arcade of both eyes. SS-OCT demonstrated masses of scleral origin. Ocular ultrasounds confirmed the calcification of these masses. RMI detected hyper-reflective images with marked superficial elevation. Systemic laboratory results did not detect any abnormalities, leading to the diagnosis of bilateral idiopathic SCC.

A rare intraocular foreign body resulting from a workplace accident.

A 54-year-old man presented to the ophthalmic emergency department of our center with eye pain and blurred vision in his right eye following a workplace accident. Examination revealed a penetrating corneal injury with the presence of an intraocular foreign body (IOFB) involving the corneoscleral limbus, perforating the cornea, iris, anterior lens capsule, and lens. Immediate surgical intervention was carried out with the extraction of the IOFB, identified as an 8mm mussel shell fragment, and the removal of the resulting traumatic cataract. Both preoperative and postoperative examinations showed an attached retina with no signs of retinal tears or vitreous hemorrhage. Appropriate management in this case, along with the timely identification of the agent, led to favorable outcomes despite the size of the intraocular foreign body.