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This work presents initial results on a multitemporal hyperspectral image analysis method to evaluate the time degradation of pork meat. The proposed method is inexpensive and practically non-destructive. The hyperspectral data is analyzed and the relevant information is reduced to the information in only three wavelengths. The analysis is performed by a binary classifier composed by two stacked autoencoders and a softmax output layer. The use of autoencoders reduces tenfold the dimension of the input space. The proposed classifier has led to 97.2% of correct decisions, which indicates the great potential of the methodology to monitor the safety of meat.

Despite the Bologna agreement implementation in 2008, teachers' education in Portugal has not changed significantly from earlier practice. The major modification in the requirements of master’s level teacher education programmes was the introduction of a strong component of educational research in a master’s degree; this is designed to replace an educational monograph in the typical 5-year ‘Licenciatura’. Both a professional one-year in-school pedagogical stage and a fifth year as a university student continue to be mandatory, as well as the stage co-supervision of the university and the school. However, existing government regulations imply that in the very near future the full professional education of teachers will have to be complemented with an in-service probation year conducted under the supervision of a school mentor. The current study has been designed to try to determine: (a) how the activities of the probation year should be organised in order to improve this stage of professional educa...

This paper proposes a new kernel Kalman filter formulation for system identification and time series estimation in nonlinear time-varying environments. The unknown nonlinear time-varying function is approximated by a finite-order linear model in a reproducing kernel Hilbert space. The model coefficients define the state of the Kalman filter. Simulation results illustrate the improvement in estimation performance provided by the new algorithm when compared to the classical kernel LMS filter.

Based on constructivism and cognitivism we believe that learning physics in schools can be faced as a process of reshaping students’ mental models about Nature’s behavior. These can correlate with existing physics misconceptions. Aware of the negative consequences of basic cognitive misunderstandings and believing that their correction, implying active and motivated students, should start from first contacts with physics knowledge in lower secondary schools, we asked three schoolteachers to participate on a pilot study with 7th, 8th and 9th graders. This study is specifically designed to promote and coach teachers’ attitudinal changes towards stronger student centered teaching behaviors. We report results obtained during academic year 2017/2018, some qualitative (from teachers diaries and recorded interviews) and a quantitative quasi-experimental study (with pre- and post-tests and control groups) with 9th graders, searching for misconceptions evolution on basic mechanics. The results obtained with 15 out of the 30 questions of the Force Concept Inventory indicate a fairly high average normalized gain for the experimental group. However, this average gain was not uniformly distributed along every FCI question, evidencing some difficulties with Newton’s 3rd law understanding. A recommended approach for its teaching in 2018/2019 produced evidence of deep learning of every tested mechanics concept.

Identification of systems with sparse impulse response encounters large applicability. Numerous techniques have been proposed to identify such systems efficiently. One strategy that leads to specially good results is to detect the active (nonzero) response samples and update only the corresponding adaptive coefficients. Wavelet-based approaches have been shown to be specially effective to this end. This paper proposes a new region-based wavelet-packet (RBWP) algorithm for efficient identification of systems with sparse impulse responses with arbitrary frequency spectra and with any delay of the effective response. The discrete wavelet packet transform (DWPT) is adaptively tailored to the energy distribution of the unknown system's response spectrum. The new algorithm leads to a reduced number of active weights and to a reduced computational complexity, when compared with competing wavelet-based algorithms. Monte Carlo simulation results show good performances regarding convergence speed and robustness to design parameter choice.

This paper presents a statistical analysis of a Pseudo Affine Projection (PAP) algorithm, obtained from the Affine Projection algorithm (AP) for a step size alpha < 1 and a scalar error signal in the weight update. Deterministic recursive equations are derived for the mean weight and for the mean square error (MSE) for a large number of adaptive taps N compared to the order P of the algorithm. Simulations are presented which show good to excellent agreement with the theory in the transient and steady states. The PAP learning behavior is of special interest in applications where tradeoffs are necessary between convergence speed and steady-state misadjustment.

This paper presents a new statistical analysis of the affine projection (AP) algorithm. An analytical model is derived for autoregressive (AR) inputs for unity step size (fastest convergence). Deterministic recursive equations are derived for the mean AP weight and mean-square error for large values of N (the number of adaptive taps). The value of N is also assumed large compared to the algorithm order (number of input vectors used to determine the weight update direction). The model predictions display better agreement with Monte Carlo simulations in both transient and steady-state than models previously presented in the literature. The model's accuracy is sufficient for most practical design purposes.

The title compound, C19H29NO, is a C17-oxime derivative of a potent aromatase inhibitor, which surprisingly has been found to have no inhibitory power. It crystallizes with two independent mol­ecules in the asymmetric unit. C=N—O—H⋯N hydrogen bonds link pairs of mol­ecules to form dimers almost parallel to the bc plane. Cohesion of the structure is also due to another three C—H⋯O hydrogen bonds directed along the a axis. This hydrogen-bonding scheme can be correlated to the almost complete loss of inhibitory power of the title compound.

The title compound, C26H38O6, has a cis junction between two of the six-membered rings (A and B). All three of the six-membered rings have chair conformations that are slightly flattened and the five-membered ring has an unusual 13β-envelope conformation. The 7α and 12α ring substituents are both axial and the 3α and 17β groups are equatorial and pseudo-equatorial, respectively. The 3α-formyloxy group is involved in one weak intermolecular C—H...O bond, which links the molecules into dimers in a head-to-head fashion.

The molecule of the title compound, C23H40O4Si2, features an approximate non-crystallographic C2 symmetry axis. The aldehyde group is disordered over two positions with similar occupancies. The geometry of the isolated molecule was studied by ab initio quantum mechanical calculations employing a molecular orbital Hartree-Fock method. The calculations reproduce well the equilibrium geometry but slightly overestimate the value of the Si-O bond lengths of the trioxadisilepine ring.

The title compound, C21H32O4 crystallizes in a triclinic unit cell, which is very unusual for steroids. The asymmetric unit contains two independent mol­ecules with almost identical geometry, although they are slighly twisted in opposite directions. These mol­ecules form a dimer inter­connected via hydrogen bonds. Both mol­ecules have a cis A/B ring junction characteristic of a 5β-configuration, but differ in the orientation of their hydroxyl groups.

The title compounds, both C23H34O5, are the 5alpha and 5beta configurations of two diacetate epimers. The 5beta-diacetate crystallizes in an hexagonal structure, unusual for steroid molecules. The unit cell has an accessible solvent volume of 358 A(3), responsible for clathrate behaviour. The 5beta-epimer also features some shorter than average bond lengths in the 3alpha,4beta-acetoxy groups. The conformations of the molecules of both epimers are compared with those obtained through ab initio quantum chemistry calculations. Cohesion of the crystals can be attributed to van der Waals and weak molecular C-H...O interactions.

Graphane, hydrogenated graphene, can be patterned into electronic devices by selectively removing hydrogen atoms. The most simple of such devices is the so-called nanoroad, analogous to the graphene nanoribbon, where confinement-and the opening of a gap-is obtained without the need for breaking the carbon bonds. In this work we address the electronic transport properties of such systems considering different hydrogen impurities within the conduction channel. We show, using a combination of density functional theory and non-equilibrium Green's functions, that hydrogen leads to significant changes in the transport properties and in some cases to current polarization.

A single-crystal synchrotron radiation study of gadolinium selenide has been made in the temperature range 15 - 100 K. GdSe has the rocksalt structure and becomes antiferromagnetic below a reported Neel temperature of 65 K. At 15 K, magnetic reflections are observed at with modulation wavevector propagating from reciprocal lattice point G. This is achieved by exploiting the resonant enhancement in the vicinity of the and edges. Similar enhancements are observed at the two edges, with the maximum effect occurring approximately 3 eV above the absorption edge. The temperature dependence of the intensity of the magnetic reflections indicates a Neel temperature of 63(1) K. These measurements, together with high-resolution studies of the fundamental reflections , contribute further evidence of magnetic or structural changes in the sample at 37(1) K. Our observations are discussed and compared with previous x-ray diffraction and magnetic susceptibility measurements.

X-ray diffraction patterns of equimolecular concentrated aqueous solutions of yttrium chloride and bromide have been investigated from s=0.4 AA-1 up to s=15 AA-1. An assumed coordination of eight water molecules around each yttrium cation, at a distance of 2.36 AA, reproduces the intensity at high s values in agreement with the values obtained by some of the present authors from EXAFS experiments. Narrow interference maxima at s=(4 pi sin theta )/ lambda approximately=0.9 AA-1 may be interpreted as the existence of a local order of the hydrated yttrium cations surrounded by anions and free water molecules. Structural models with and without close packing of the hydrated cations were built to simulate that local order.

The title compound, C25H34O6, has a 3β,21-configuration, with the epoxy O atom at 16α,17α. Rings A and C have chair conformations which are slightly flattened. Because of the presence of a double bond, ring B assumes an 8β,9α-half chair conformation. Ring D has a conformation close to a 14α-envelope. Cohesion of the crystal can be attributed to van der Waals interactions and weak C—H⋯O interactions.

In the title compound, C17H27NO4, which is an hydrosinapic acid derivative with increased lipophilicity conferred by an additional alkyl chain, the central and the hexyl linear chains contain slightly shorter bond lengths [C—N = 1.316 (2) Å; average linear chain C—C = 1.487 (6) Å] than reported average values [Csp2—N = 1.334, C—C for CH2—CH2 = 1.524 and 1.513 Å for CH2—CH3]. The 4-hydroxy-3,5-dimethoxyphenyl plane [r.m.s. deviation 0.055 (12) Å] makes an angle of 59.89 (5)° with the central plane of the molecule (composed of the N atom, the carbonyl group and the two methylene C atoms linking the carbonyl group and the ring, [r.m.s. deviation 0.0026 (10) Å], which, in turn, makes an angle of 64.24 (13)° with the essentially planar hexyl chain [r.m.s. deviation 0.035 (18) Å]. The N—H group of the amide group is involved in a bifurcated hydrogen bond towards the hydroxy and one of the methoxy O atoms of the 4-hydroxy-3,5-dimethoxyphenyl substituent of a neighbouring molecule, forming a two-dimensional network in the (100) plane. In addition, the same hydroxy group acts as a donor towards the carbonyl O atom of another neighbouring molecule, forming chains running along the b axis.

In the title compound, C20H26O2, which is the 6-methylene derivative of androstenedione and a synthetic percursor of exemestane, the steroidAring approximates to a sofa (or envelope) conformation, with the methylene group adjacent to the link to theBring lying out of the plane of the other atoms. TheBandCrings have slightly flattened chair conformations and theDring is an envelope, with the CH group forming the flap. In the crystal, molecules are linked by two distinct C—H...O hydrogen bonds, involving acidic H atoms close to C=C and C=O double bonds.

The ring conformation of the title compound, C19H30O3, is similar to that of the 5α-epimer except for the cis A/B ring junction. Ring D adopts a 13β,14α-half chair conformation. The mol­ecules are linked together by a two-dimensional network of hydrogen bonds involving the carbonyl and hydroxyl groups.

The title compound, C25H36O5, has two independent mol­ecules in the asymmetric unit with similar geometry. The main difference between the two mol­ecules relates to the conformation of the 17β-methyl ketone and 3β-acetoxy groups, the latter being disordered in one of the mol­ecules. The five-membered ring adopts an unusual 13β-envelope conformation.

The title cholestan, C(28)H(46)O(3), was prepared by epoxidation of 7-norcholest-5-en-3β-yl acetate and crystallized by slow evaporation from an ethano-lic solution. All rings are trans fused. The 3β-acetate and the 17β-cholestane side chain are in equatorial positions. The mol-ecule is highly twisted due to its B-nor characteristic. A quantum chemical ab-initio Roothaan Hartree-Fock calculation of the equilibrium geometry of the isolated mol-ecule gives values for bond lengths and valency angles in close agreement with the experimental ones.

The title hydrated tetrol, C(19)H(32)O(4)·3H(2)O, was synthesized by stereoselective reduction of the compound 3β,5α,6β-trihy-droxy-androstan-17-one. All rings are fused trans. The organic mol-ecules are connected head-to-tail along the c axis via O-H⋯O hydrogen bonds. Layers of water mol-ecules in the ab plane inter-connect these chains. A quantum chemical ab initio Roothan Hartree-Fock calculation of the isolated mol-ecule gives values for the mol-ecular geometry close to experimentally determined ones, apart from the C-O bond lengths, whose calculated values are significantly smaller than the measured ones, probably a consequence of the involvement of the C-OH groups in the hydrogen-bonding network.

The title compound, C(19)H(30)O(4), is an androstan-17-one derivative synthesized from the dehydro-epiandrosterone through a sequential addition of an oxidant, followed by a trans-diaxial opening of the epoxide generated, with Bi(OTf)(3) (OTf is trifluoro-methane-sulfonate). The six-membered rings have a slightly flattened chair conformation, while the five-membered ring adopts a 14-α envelope conformation. All rings are trans fused. In the crystal, the mol-ecules are connected by O-H⋯O hydrogen bonds involving the hydroxyl and carbonyl groups, forming a three-dimensional network. A quantum mechanical ab initio Roothan Hartree-Fock calculation of the free mol-ecule gives bond lengths, valency angles and ring torsion angles of the free molecule at equilibrium geometry (energy minimum) close to the experimental values.

X-ray diffraction data were collected at room temperature for two rutile structures, NiF 2 and CoF 2 . Two different crystals of each compound have been used in the experiments. Atomic and thermal parameters were derived from least-squares refinements of high-angle data [(sinθ)λ≥0.6 A -1 ]. The results of Fourier inversion of the differences between observed and model structure factors are presented and discussed in terms of difference density maps

In the title compound, C23H34O4, the two saturated six-membered rings have slightly flattened chair conformations and the unsaturated ring assumes a 8β,9α-half chair conformation distorted towards a 8β-sofa. The five-membered ring has an unusual conformation close to a 13β-envelope. The acetoxy and methyl ketone substituents are twisted with respect to the average molecular plane of the steroid nucleus. The mol­ecules are hydrogen-bonded head-to-head via the hydroxy and methyl ketone groups forming dimers, which are stacked in planes perpendicular to the b axis.

The title compound, C23H32O4, has a 3β configuration, with the epoxy O atom at 16α,17α. Rings A and C have slightly distorted chair conformations. Because of the presence of the C5=C6 double bond, ring B assumes an 8β,9α-half-chair conformation slightly distorted towards an 8β-sofa. Ring D has a conformation close to a 14α-envelope. The acetoxy and acetyl substituents are twisted with respect to the average molecular plane of the steroid. The conformation of the mol­ecule is compared with that given by a quantum chemistry calculation using the RHF–AM1 (RHF = Roothaan Hartree–Fock) Hamiltonian model. Cohesion of the crystal can be attributed to van der Waals interactions and weak intermolecular C—H⋯O interactions, which link the mol­ecules head-to-tail along [101].

In the title 6–6–6–5 fused ring compound, C19H28O, all the ring junctions are trans. The unsaturated ring A shows a conformation intermediate between a 10β-sofa and a 1α,10β-half-chair.

The title compounds, C(17)H(13)FN(2)O(3) and C(18)H(16)N(2)O(4), are new potent aromatase inhibitors combining the common features of second- and third-generation nonsteroid anti-aromatase compounds. The molecules have a propeller shape, with dihedral angles between adjacent planes in the range 49-86°. A quantum mechanical ab initio Roothaan-Hartree-Fock calculation for the isolated molecules shows values for these angles close to the ideal value of 90°. Docking studies of the molecules in the aromatase substrate show that their strong inhibitor potency can be attributed to molecular flexibility, hydrophobic interactions, heme Fe coordination and hydrogen bonding.

The ring conformation of the title compound, 3α,4β-di-hydroxy-5a-androstan-17-one, C 19 H 30 O 3 , is similar to that of the 5β-epimer except for the trans A/B ring junction and the geometry of ring D, which adopts a slightly deformed 13,14-half-chair conformation instead of the more common 14α-envelope conformation. The molecules are linked together by a two-dimensional network of hydrogen bonds involving the carbonyl and hydroxyl groups.

The dihedral angles between ring planes of the title compound, C 19 H 26 O 4 , a D-ring lactone, indicate a slightly curved molecular profile. All ring junctions are trans. A hydrogen bond between the hydroxyl group of ring A and the carbonyl group of ring D links the molecules head-to-tail in helical chains parallel to the 2 1 screw axis along a.

The title compound, C23H32O4, has a 3β configuration, with the epoxy O atom at 16α,17α. Rings A and C have slightly distorted chair conformations. Because of the presence of the C5=C6 double bond, ring B assumes an 8β,9α-half-chair conformation slightly distorted towards an 8β-sofa. Ring D has a conformation close to a 14α-envelope. The acetoxy and acetyl substituents are twisted with respect to the average molecular plane of the steroid. The conformation of the mol­ecule is compared with that given by a quantum chemistry calculation using the RHF–AM1 (RHF = Roothaan Hartree–Fock) Hamiltonian model. Cohesion of the crystal can be attributed to van der Waals interactions and weak intermolecular C—H⋯O interactions, which link the mol­ecules head-to-tail along [101].

In the crystal structure of the title compound, C(21)H(32)O(2), ring A is highly distorted, with a conformation inter-mediate between 10β-sofa and 1α,10β-half chair; rings B and C have slightly flattened chair conformations. Ring D assumes an unusual 13β-envelope conformation, probably induced by the acet-oxy substituent. Cohesion of the crystal structure is due only to weak van der Waals inter-actions.

The asymmetric unit of the title compound, C 19 H 28 O 3 , contains two independent molecules with almost identical geometry. The molecules have a planar 5a configuration as a result of a trans-A/B junction of the rings. The compound crystallizes in a triclinic cell, which is unusual for steroids. The molecules are linked head-to-tail via hydrogen bonds between the ring A hydroxyl group and the ketone group of ring D, forming two independent chains running along the c axis.

The title compound, C 23 H 34 O 6 , a ring D lactone, has two acetoxy groups in positions 3α and 4β. All ring junctions are trans which results in a planar molecule. The two acetoxy groups have different behaviour, one of them being disordered and exhibiting double-bond delocalization. The ordered acetoxy group is involved in two weak intramolecular C-H… O bonds.

The title compound, C 19 H 26 O 4 , has a C5 atom with an unusual environment, which leads to a molecular 5α configuration. Ring A is highly flattened. The carbaldehyde group is slightly disordered, with interchange of the H and O positions.

The title compound, C(19)H(29)NO, is a C17-oxime derivative of a potent aromatase inhibitor, which surprisingly has been found to have no inhibitory power. It crystallizes with two independent molecules in the asymmetric unit. C=N-O-H...N hydrogen bonds link pairs of molecules to form dimers almost parallel to the bc plane. Cohesion of the structure is also due to another three C-H...O hydrogen bonds directed along the a axis. This hydrogen-bonding scheme can be correlated to the almost complete loss of inhibitory power of the title compound.

The title compound, C(21)H(28)O(4), has a 4-acetoxy substituent positioned on the steroid alpha face. The six-membered ring A assumes a conformation intermediate between 1alpha,2beta-half chair and 1alpha-sofa. A long Csp(3)-Csp(3) bond is observed in ring B and reproduced in quantum-mechanical ab initio calculations of the isolated molecule using a molecular-orbital Hartree-Fock method. Cohesion of the crystal can be attributed to van der Waals interactions and weak C-H...O hydrogen bonds.

The ring conformation of the title compound, 3α,4β-di-hydroxy-5a-androstan-17-one, C 19 H 30 O 3 , is similar to that of the 5β-epimer except for the trans A/B ring junction and the geometry of ring D, which adopts a slightly deformed 13,14-half-chair conformation instead of the more common 14α-envelope conformation. The molecules are linked together by a two-dimensional network of hydrogen bonds involving the carbonyl and hydroxyl groups.

The molecule of the title compound, C23H40O4Si2, features an approximate non-crystallographic C2 symmetry axis. The aldehyde group is disordered over two positions with similar occupancies. The geometry of the isolated molecule was studied by ab initio quantum mechanical calculations employing a molecular orbital Hartree-Fock method. The calculations reproduce well the equilibrium geometry but slightly overestimate the value of the Si-O bond lengths of the trioxadisilepine ring.

The title compound, alternatively called 24-nor-5 beta-chol-22-ene-3 beta,7 alpha,12 alpha-triyl triformate, C(26)H(38)O(6), has a cis junction between two of the six-membered rings. All three of the six-membered rings have chair conformations that are slightly flattened and the five-membered ring has a 13 beta,14 alpha-half-chair conformation. The 3 beta, 7 alpha and 12 alpha ring substituents are axial and the 17 beta group is equatorial. The 3 beta-formyloxy group is involved in one weak intermolecular C-H...O bond, which links the molecules into dimers in a head-to-head fashion.

The title compound, C(19)H(26)O(2), a B-norandrogen with a 6beta-methyl group, is a recently identified and experimentally tested potent new aromatase inhibitor. It shares structural and physicochemical similarities both with the natural substrate of the enzyme, androstenedione, and with exemestane, another potent aromatase inhibitor having a 6-methylidene group. X-ray diffraction results indicate that the B-nor molecule and exemestane have nearly the same oxygen-oxygen and methyl-methyl separations, though they have distinct configurations of the hydrophobic groups at the 6-position. These structural comparisons allow correlations to be inferred between the active site geometry of the molecules and the aromatase inhibition power of the studied compound.

Caregiving and related concepts such as family or caregiver burden have been widely discussed in recent literature. A descriptive, cross-sectional study was conducted in a sample (n = 80) of primary caregivers to severe mental patients (diagnosed schizophrenia, chronic psychosis or affective disorder).To describe the caregivers' and corresponding patients' sample, as well as the nature of existing relationships. Levels of caregiver burden and psychological distress were evaluated and a preliminary analysis conducted on objective and subjective burden correlation.Involvement Evaluation Questionnaire (IEQ), General Health Questionnaire (GHQ) and a semi-structured interview designed for this purpose.The extent of burden was found significant in this sample, being unevenly distributed in its components (e.g. tension, worrying or financial burden). Forty-one percent of caregivers experienced minor psychiatric morbidity. Measures of objective and subjective burden were moderately correlated. The same applied to magnitude of associations between each of them and distress parameters. Higher levels of burden were found in groups of caregivers to more severely ill or disabled patients, while diagnosis was not important for this purpose.Most relatives remain highly involved. These results suggest the need to implement specific interventions addressing psychotic patients as well as their families.

The serum values of the total biliary acids were dosed through the enzymatic-colorimetric method in 15 dyspeptic persons with no hepatic disease (control-group) and in 52 patients with chronic hepatic disease of alcoholic etiology, subdivided according to the Child-Pugh functional classification (Child A = 17; Child B = 18, and C = 17) or according to the clinic exam in one compensated group (n = 22) and in one decompensated group (n = 30). The serum dosages of the biliary acids, particularly the posprandial ones, presented high discriminative power in the detection of chronic hepatopathy, separating the control-group from any of the other groups of alcoholic patients with chronic hepatopathy. The dosages also presented significant correlation with the biochemical tests more directly related to the hepatocellular function, as albumin, total bilirubin and the activity of prothrombin, besides the Child-Pugh numeric score classification. Nevertheless, when the cirrhotic patients were separated in accordance with the clinical presentation, the serum dosage of the biliary acids presented inferior discriminative capacity in relation to the conventional exams as the Child-Pugh numeric classification and the time of prothrombin. Therefore, demonstrating to have limited value in the functional evaluation and in the evolutional following-up of the alcoholic chronic hepatopathy.