Hard and Easy Instances of L-Tromino Tilings

We study tilings of regions in the square lattice with L-shaped trominoes. Deciding the existence of a tiling with L-trominoes for an arbitrary region in general is NP-complete, nonetheless, we identify restrictions to the problem where it either remains NP-complete or has a polynomial time algorithm. First, we characterize the possibility of when an Aztec rectangle and an Aztec diamond has an L-tromino tiling. Then, we study tilings of arbitrary regions where only $180^\circ$ rotations of L-trominoes are available. For this particular case we show that deciding the existence of a tiling remains NP-complete; yet, if a region does not contains certain so-called "forbidden polyominoes" as sub-regions, then there exists a polynomial time algorithm for deciding a tiling.Comment: Full extended version of LNCS 11355:82-95 (WALCOM 2019

Validation Study of the Use of Matlab/Simulink Synchronous-Machine Block for Accurate Power-Plant Stability Studies

This paper presents results of the validity study of the use of MATLAB/Simulink synchronous-machine block for power-system stability studies. Firstly, the waveforms of the theoretical synchronous-generator short-circuit currents are described. Thereafter, the comparison between the currents obtained through the simulation model in the sudden short-circuit test, are compared to the theoretical ones. Finally, the factory tests of two commercial generating units are compared to the response of the synchronous generator simulation block during sudden short-circuit, set with the same real data, with satisfactory results. This results show the validity of the use of this generator block for power plant simulation

Recent advances in the aqueous chemistry of the calcium(II)-gluconate system – Equilibria, structure and composition of the complexes forming in neutral and in alkaline solutions

Of the sugar carboxylates, D-gluconate is clearly the most significant representative: the world’s annual production of this organic compound is estimated to be in the order of 10$^{5}$ tonnes. The reason of its mass production is due to its outstandingly broad range of practical (medical, pharmaceutical, industrial, etc.) applications. D-gluconate is a well-known and exceptionally popular complexing agent; accordingly, it has been the subject of a large number of coordination chemical research investigations. Its complexation properties are specially remarkable in alkaline to hyperalkaline pH conditions, where the deprotonation of one or more of its alcoholic OH groups provides a favourable frame for the formation of very stable chelate complexes with a large variety of metal cations. With the aim to show the state of the art of some relevant issues in the aqueous chemistry of the D-gluconate ion, the current paper focusses on the acidbase properties and calcium(II) complexation of the compound encompassing the entire experimentally available pH-range in water. The accessible literature on the deprotonation of carboxylic and alcoholic OH groups is collected and critically evaluated. The lactonization equilibria of D-gluconic acid are also scrutinized. The available data on the calcium complexes forming in neutral and in (hyper)alkaline solutions (both in terms of composition, formation constants and solution structure) are also discussed. Where feasible, some of these properties are compared with those of D-glucose and its derivatives as well as some less common sugar carboxylates, structurally related to D-gluconate, (i.e., D-heptagluconate, Lgulonate and α-D-isosaccharinate). Special emphasis is laid on the relationship between complex stability and the type of metal-binding groups

Antiagregación y anticoagulación en síndromes coronarios agudos: niveles de evidencia

Management of acute coronary syndromes (ACS) has moved rapidly in parallel with our understanding of the pathophysiological basis of the disease. In the eighties, the demonstration of the pivotal role of coronary thrombosis in the etiology of a ACS led to administration of aspirin and unfractionated heparin. In recent years, new medical and invasive therapies have been developed: anti-platelets (thienopyridines and glycoprotein Ilb/IlIa inhibitors), antithrombins (low molecularweight heparins) and most recently, factor Xa inhibitors (pentasaccharides). As new treatments are rapidly added, clinicians are constantly challenged to incorporate new information and guidelines into their practices in a timely fashion

Diagnóstico y tratamiento de la trombosis venosa profunda

Deep-vein thrombosis (DVT) is a common condition that can lead to complications such as postphlebitic syndrome, pulmonary embolism and death. Currently, an algorithm strategy combining pretest probability, D-dimer testing and compression ultrasonography imaging allows for safe and convenient estimation of suspected lower-limb thrombosis. The mainstay of treatment is anticoagulation therapy. The use of low-molecular-weight heparin or pentasaccharide (fondaparinux) allows for outpatient management of most patients with DVT. The duration of anticoagulation depends on whether the primary event was idiopathic or secondary to a transient risk factor. Interventions such as thrombolysis and placement of inferior vena cava filter are reserved for special situations

Efecto de la raza y la edad sobre las concentraciones de hormonas tiroideas t3 y t4 de bovinos en condiciones tropicales

Para estudiar el efecto en condiciones de trópico seco de la edad y del grupo racial sobre las concentraciones séricas de las hormonas tiroideas T3 y T4, se muestrearon 158 animales de los grupos raciales Holstein, Lucerna, Hartón del Valle, Cebú Brahman y mestizo F1 (Cebú Brahman x Pardo Suizo), distribuidos en cuatro grupos de edad desde el nacimiento hasta el destete (8 meses). La concentración media de T3 fue 2.25 mmol/L y la de T4, 57.37 mmol/L. La correlación entre T3 y T4 fue de 0.53. Se encontró diferencia estadísticamente significativa para el efecto grupo racial, grupo de edad (P and lt;0.001) pero no para la interacción grupo racial x edad (p=0.286). Los grupos raciales con concentraciones más elevadas fueron Holstein y Lucerna; la concentración más baja se presentó en los bovinos mestizos. La mayor concentración de hormonas tiroideas según la edad ocurrió en recién nacidos, luego descendió progresiva y linealmente. El trabajo encontró que en condiciones de trópico seco, en zona límite de termoneutralidad según el índice ITH, los bovinos jóvenes presentanron diferencias marcadas en las concentraciones de hormonas tiroideas.Palabras claves: Adaptación; Bovinos; Crecimiento; Tiroides.To study the effect of age and breed on blood concentration of thyroid hormones T3 and T4 under the dry tropic conditions, 158 animals from the groups Holstein, Lucerna, Hartón del Valle, Brahman and crossbred F1 Brahman x Brown Swiss were sampled. The animals were allocated in four age groups from newborns calves until eight month old. The average T3 concentration was of 2.25 mmolL-¹ and the T4 was of 57.37 mmolL-¹. The correlation between T3 and T4 was of 0.53. A statistical significant difference (p and lt;0.001) was found for the effects of age breed and group, but not difference was found for the interaction between breed and age (p=0.286). The breeds with higher blood concentrations of T3 and T4 were Holstein and Lucerna. The lowest concentration was found among the crossbred group. The higher concentration of T3 and T4 of thyroid hormones was found in the newborn group. As the calves grow, the concentrations of T3 and T4 decrease progressively. This study found that under dry tropic conditions, in a thermo-neutral borderline zone (according to the THI index) the young bovines show clear differences in the concentration of the thyroid hormones.Key words: Adaptation; Bovine; Growth; Thyroids

The Use of Electrochemical Noise in the Study of Nanometric Coatings

This chapter presents the study and analysis of the application of nanometric films of SS 304 and nanometric Al/Cr and Cr/Al bilayers deposited on different aluminum and steel alloys by magnetron sputtering and DC sputtering. The materials were characterized by scanning electron microscopy (SEM) and electrochemical noise in order to consider their application as high corrosion resistance coatings. The corrosion behavior of the films was studied using a NaCl aqueous solution (3.5 wt%)

Impact of the degradation leachate of the polyacrylonitrile-based material UP2W on the retention of Ni(II), Eu(III) and Pu(IV) by cement

The uptake of $^{63}$Ni(II), $^{152}$Eu(III) and $^{242}$Pu(IV) by hardened cement paste (HCP, CEM I) in the degradation stage II (pH ≈ 12.5, [Ca] ≈ 0.02 M) was investigated in the presence of a degradation leachate of UP2W, a polyacrylonitrile-based (PAN) material used as a filter aid in nuclear power plants. The degradation leachate with a concentration of dissolved organic carbon of ∼40 ppm was obtained from the degradation of UP2W in portlandite-buffered solutions for ca. 1100 days. Redox conditions in the Pu systems were buffered with hydroquinone, which defines mildly reducing conditions (pe + pH ≈ 10) where Pu(IV) is the predominant oxidation state. The degradation leachate investigated in this work is moderately sorbed by cement, with distribution ratios (R$_d$) of (0.35 ± 0.15) m$^3$ kg$^{−1}$. These values are 30 to 100 times greater than distribution ratios previously reported for proxy ligands of PAN degradation products, i.e., glutaric acid, α-hydroxyisobutyric acid and 3-hydroxybutyric acid. The presence of the degradation leachate induces a moderate decrease in the uptake of $^{63}$Ni(II), $^{152}$Eu(III) and $^{242}$Pu(IV) by cement, as compared to the sorption in the presence of the proxy ligands. Nevertheless, retention in the presence of the degradation leachate remains high for all investigated radionuclides, with Rd($^{63}$Ni(II)) ≈ 2 m$^3$ kg$^{−1}$, Rd($^{152}$Eu(III)) ≈ 100 m$^3$ kg$^{−1}$ and Rd($^{242}$Pu(IV)) ≈ 30 m$^3$ kg$^{−1}$. These observations possibly reflect that the multiple functionalities (–COOH, –OH, amide groups) expected in the macromolecules (10–15 kDa) present in the degradation leachate, can offer further binding/chelating capabilities compared to the small organic proxy ligands with at most bidentate binding

Soil Moisture and Black Truffle Production Variability in the Iberian Peninsula

The relationship between modelled root zone soil moisture (SM) and black truffle production in the Iberian Peninsula was studied. Previous works have investigated the influence that precipitation exerts on truffle yield highlighting the importance of water for the growth of black truffle. However, SM had not been used until now due to the lack of suitable databases. The SM series from the LISFLOOD hydrological rainfall–runoff model was used in this study. Annual black truffle yield series from 175 locations in Spain was correlated with SM for the period 1991–2012. For this, different approaches were applied considering daily, weekly and monthly temporal scales. The same analysis was carried out using precipitation data to compare the behaviors of both variables related to truffle production variability. The results obtained show critical periods in terms of soil water content in summer (June–September) and during October–November months. Moreover, a clear delay between precipitation and SM influence on black truffle was observed. The results obtained in this study highlight the importance of SM for black truffle production, since this variable truly expresses the available water for this fungus, which completes its entire life cycle living below ground. © 2022 by the authors. Licensee MDPI, Basel, Switzerland