Optical and thermal properties of edible coatings for application in solar drying.

Solar drying is a sustainable process that may impact the quality of dried food. This is because, pigments contained in food are sensitive to sunlight, and exposure to ultraviolet radiation can affect them. We applied biopolymer-based coatings on strawberry, from hydro-colloidal solutions of Opuntia ficus indica-mucilage, fenugreek, xanthan gum, gum Arabic, and guar gum to evaluate their potential use as UV filters for solar drying of food. Thermal properties and the optical transmittance, absorbance and reflectance of the coatings were measured to assess their influence on food-sunlight interaction. During the drying experiments, the moisture content, total anthocyanins (TA), and total phenolic compounds (TPC) were measured. Optical and thermal properties are influenced by the biopolymer-based coatings. Also, the optical properties are influenced by the coating thickness. The differences in optical and thermal properties influence the drying process. Differences exist in the drying rate for strawberry slices with coating, compared with those without the coatings. In general, the TA and TPC content in the product are better preserved under solar drying than in control experiments done in a drying oven. A partial transmittance of solar UV radiation is recommended to obtain increased TA and TPC contents in the dried product.

Delayed lower extremity paresis following iliosacral screws: Atypical complication and treatment.

Percutaneous iliosacral screw placement has become the technique of choice for treating injuries to the posterior pelvis. However, the technique requires an understanding of the anatomy surrounding the bone corridors to avoid complications and detect them early if they occur. We present the clinical case of a patient with a U-shaped fracture of the sacrum that evolves with gluteal pain and left foot equine paresis after percutaneous fixation with iliosacral screws. Angio-CT of the pelvis shows active arterial bleeding from the superior gluteal artery associated to extensive hematoma in the thickness of the gluteus medius muscle. Emergency embolization is performed by installing coil and gelatin. Successful control of bleeding is achieved. To avoid this complication, a complete imaging study is recommended in planning the surgery and to avoid multiple repositioning of the guide or screw. Arterial injury should be suspected in case of increasing pain despite analgesia, functional impairment or neurological deficit and the angiographic study and resolution by selective embolization of the bleeding vessels must be performed.

Morphological abnormalities of the hip in acetabular fractures.

Poor prognosis factors in surgical treatment of acetabular fracture-dislocations have been well established but there is little information about how morphological abnormalities of the hip may affect the surgical outcome. Hip anatomy has a wide range of variations. Morphological abnormalities of the hip can also be observed in patients with acetabular fractures. We present a case of a complication in a patient with a complex acetabular fracture, acetabular retroversion and femoroacetabular impingement. A 31-year old male patient was transferred to our trauma center following a high speed road traffic accident. Trauma series CT revealed cerebral contusion, subdural hematoma, aortic dissection and a left transverse plus posterior wall acetabular fracture. The left hip was reduced and the acetabular fracture was treated with a Kocher Langenbeck approach in prone position. The pelvic X- ray evidenced an anatomic reduction and signs of acetabular retroversion with positive posterior wall sign and crossover sign. CT scan evidenced increased alpha angle in the femoral head neck junction. During the follow up, 2 months after the acetabular fixation, patient suffered a posterior left hip dislocation and a total cementless hip arthroplasty was performed. Patients with acetabular retroversion and femoroacetabular impingement (CAM lesion) may be at risk of posterior dislocation. The influence of acetabular version and impingement may be also closely involved in how challenging the determination of hip stability can be in patients with posterior wall acetabular fractures. Acetabular retroversion and FAI may be related to the dislocation of unstable patterns with small fragments (wall sizes less than 20%). In this case postoperative precautions were not enough. We believe capsular reattachment with anchors and bracing may be useful in these selected cases. As these patients are not candidates for retroPAO (the recommended treatment for acetabular retroversion) maybe arthroscopic anterior wall riming and CAM resection should be performed at an early stage to decrease or avoid fulcrum.

Stochastic optimization of broadband reflecting photonic structures.

Photonic crystals (PCs) are built to control the propagation of light within their structure. These can be used for an assortment of applications where custom designed devices are of interest. Among them, one-dimensional PCs can be produced to achieve the reflection of specific and broad wavelength ranges. However, their design and fabrication are challenging due to the diversity of periodic arrangement and layer configuration that each different PC needs. In this study, we present a framework to design high reflecting PCs for any desired wavelength range. Our method combines three stochastic optimization algorithms (Random Search, Particle Swarm Optimization and Simulated Annealing) along with a reduced space-search methodology to obtain a custom and optimized PC configuration. The optimization procedure is evaluated through theoretical reflectance spectra calculated by using the Equispaced Thickness Method, which improves the simulations due to the consideration of incoherent light transmission. We prove the viability of our procedure by fabricating different reflecting PCs made of porous silicon and obtain good agreement between experiment and theory using a merit function. With this methodology, diverse reflecting PCs can be designed for any applications and fabricated with different materials.

[Arthroscopy after hip joint injury. Case studies and indications]. / Arthroskopie nach Trauma des Hüftgelenks. Fallbeispiele und Indikationen.

Intra-articular injuries are common after dislocation and fracture of the hip joint and can be addressed using hip arthroscopy. The most common indications for this procedure are loose bodies, labral tears and chondral defects. In addition, preexisting femoroacetabular impingement can be addressed at the time of surgery. Arthroscopically guided fracture reduction and fixation has been described. We present two case reports of intra-articular lesions after traumatic hip dislocation. The first is a case of a man with an anterior labral tear and loose bodies after closed hip reduction. The second case is a man with a large anterior labral tear with preexisting femoroacetabular impingement. Both of them were treated by arthroscopic debridement of the unstable labrum. In addition loose bodies were removed in the first patient and a femoral osteoplasty was performed in the second patient. Hip arthroscopy has proven to be a safe and effective surgical technique for treating specific post-traumatic lesions and preexisting femoroacetabular impingement. The current case reports provide an overview of the indication for hip arthroscopy following traumatic injuries to the hip.

A plausible explanation for heart rates in mammals.

We consider a simple model to give a plausible mechanical explanation of what are the actual resting heart rates of mammals optimized for. We study what is the optimal frequency for a viscoelastic fluid circulating in a pulsatile way through a network of tubes and conclude that the heart rate is not optimized to transport blood through the whole net. Rather, actual resting heart rates of mammals happen at frequencies that optimize flow in vessels of radii that correspond to large arteries, which bring oxygenated blood rapidly far away from the heart, towards head and limbs. Our results for the optimal frequencies, obtained using observed radii of femoral arteries in mammals, agree best with the heart rates observed. We find a theoretical allometric relation between optimal flow frequency and radius: nu approximately R(-1). This one, agrees with the exponent obtained when plotting observed heart rates versus radii of both, femoral arteries and carotids in mammals of different sizes, from mice to horses.

Perfect light transmission in Fibonacci arrays of dielectric multilayers.

In this paper we study the propagation of light through an asymmetric array of dielectric multilayers built by joining two porous silicon substructures in a Fibonacci sequence. Each Fibonacci substructure follows the well-known recursive rule but in the second substructure dielectric layers A and B are exchanged. Even without mirror symmetry, this array gives rise to multiple transparent states, which follow the scaling properties and self-similar spectra of a single Fibonacci multilayer. We apply the transfer matrix formalism to calculate the transmittance. By setting the transfer matrix of the array equal to ± I, the identity matrix, frequencies of perfect light transmission are reproduced in our theoretical calculations. Although the light absorption of porous silicon in the optical range limits our experimental study to low Fibonacci generations, the positions of the transparent states are well predicted by the above-mentioned condition. We conclude that mirror symmetry in arrays of Fibonacci multilayers is sufficient but not necessary to generate multiple transparent states, opening broader applications of quasiperiodic systems as filters and microcavities of multiple frequencies.

Highly visible science: a look at three decades of research from Argentina, Brasil, México and Spain

Dado que la visibilidad internacional de la investigación científica es de especial importancia para los países en desarrollo, fueron analizados los trabajos publicados entre 1973 y 2005 por los tres países más productivos de Latinoamérica, Argentina, Brasil y México, en las revistas multidisciplinarias Nature y Science, comparándolos con los de España. El número total de las contribuciones fue de 696 para España, 411 para Brasil, 227 para México y 127 para Argentina. Tanto España como Brasil publicaron más del 65 por ciento del respectivo total en Nature, mientras que en el caso de México y Argentina, la producción entre las dos revistas fue más equilibrada. Se notó una creciente presencia de los cuatros países a lo largo de los 33 años estudiados, especialmente con respecto a España a partir de 1993. Todos los países mostraron un alto nivel de colaboración internacional (72-75 por ciento). Las instituciones latinoamericanas con más presencia fueron las grandes universidades nacionales. Entre 12 y 18 por ciento de las contribuciones por país no fueron citados y tres trabajos sobre el genoma recibieron más de 2000 citas. Un análisis de las revistas más citadas mostró la concentración de títulos en Física, Astronomía y Astrofísica, Geociencias y Biología Molecular, resultados que se reflejaron de igual forma en los temas resultantes de un proceso de minería de textos en los resúmenes.

Natural materials for treatment of industrial effluents: comparative study of the retention of Cd, Zn and Co by calcite and hydroxyapatite. Part I: batch experiments.

This work explores the heavy metal retention capacity of materials developed from minerals that are abundant in nature, with low cost and minimum environmental impact. To accomplish this objective we have: (a) characterized commercial samples of calcite (CA) and hydroxyapatite (HAP)--including their surface properties (BET area, electrophoretic mobility, SEM, and X-ray energy dispersive spectroscopy); and, (b) qualified and quantified the interaction of Cd, Zn and Co with calcite (CaCO3) and hydroxyapatite [Ca5(PO4)3OH] through batch experiments, in a range of metal concentrations (4Zn>Co and Cd>Zn approximately Co, respectively. Retention increased with pCa and pH and could be modeled by: (a) a non-ideal ion exchange mechanism (Me/Ca) for the adsorption of Cd, Zn and Co onto CA; and, (b) a mechanism of non-ideal ion exchange and specific adsorption (Me/Ca and identical with PO4O-Me) in the case of HAP. The pH dependence is indirect in CA and is related to its solubility changes (pCa increases with pH, and so does sorption of Cd, Zn and Co). Both materials, HAP and CA, can be used for heavy metal retention. The former has better performance for water treatment due to its greater efficiency for the retention of Cd, Zn and Co (over two orders of magnitude per gram of material) and its lower solubility in a wide range of pH (6

[Spinocerebellar ataxia type 7: clinical and molecular genetic analysis of a Mexican family]. / Ataxia espinocerebelosa tipo 7: descripcion de una familia mexicana.

INTRODUCTION: Spinocerebellar ataxias (SCA) constitute a group of neurodegenerative diseases characterized by cerebellar disfunction alone or associated with other neurological anomalies. The combination of progressive cerebellar ataxia, macular pigment dystrophy, ophtalmoplegia, spasticity and an autosomal dominant pattern of transmission is characteristic of SCA 7. Genome wide linkage analysis mapped the defective gene to 3p12 13. OBJECTIVE: To describe a Mexican family with SCA 7. CASE REPORTS: We present a family pedigree of 13 individuals with ataxia and other neurologic findings in 3 generations. The evaluation consisted of a complete clinical and neurologic examination; neuropsychologic, neurophysiologic, ophthalmologic, neuroradiologic assessments and a molecular genetic study. The first 2 generations had a history of gait disturbance and visual loss. We objectively found a global cerebellar syndrome, pyramidal signs, visual impairment and ophtalmoparesis in variable grades in all members of the third generation All had progressive retinal degeneration, cerebellar, brainstem and hemispheric atrophy. We observed anticipation phenomena. Genetic analysis of the father of the third generation showed expansion of CAG triplet repeats at the SCA 7 gene. CONCLUSION: The clinical and genetic findings confirmed the diagnosis of SCA 7, and this is the first report in a Mexican family.

Photon BLOCH oscillations in porous silicon optical superlattices.

We report the first observation of oscillations of the electromagnetic field in an optical superlattice based on porous silicon. These oscillations are an optical equivalent of well-known electronic Bloch oscillations in crystals. Elementary cells of our structure are composed by microcavities whose coupling gives rise to the extended collective modes forming optical minigaps and minibands. By varying thicknesses of the cavities along the structure axis, we have created an effective electric field for photons. A very high quality factor of the confined optical state of the Wannier-Stark ladder may allow lasing in porous silicon-based superlattices.

Experimental observation of dramatic differences in the dynamic response of Newtonian and Maxwellian fluids.

An experimental study of the dynamic response of a Newtonian fluid and a Maxwellian fluid under an oscillating pressure gradient is presented. Laser Doppler anemometry is used in order to determine the velocity of the fluid inside a cylindrical tube. In the case of the Newtonian fluid, the dissipative nature is observed. In the dynamic response of the Maxwellian fluid an enhancement at the frequencies predicted by theory is observed.

Dynamic permeability of electrically conducting fluids under magnetic fields in annular ducts.

The dynamic response of an electrically conducting fluid (either Newtonian or Maxwellian) flowing between straight concentric circular cylinders under a constant radial magnetic field, is analyzed. The isothermal flow is studied using the time Fourier transform, so that the dynamic generalization of Darcy's law in the frequency domain is obtained and analytical expressions for the dynamic permeability are derived. For the Newtonian case, the range of frequencies where the dynamic permeability approaches the static value is enlarged the smaller the gap between the cylinders and the higher the magnetic-field strength. For the Maxwell fluid, the presence of the inner cylinder shifts the frequencies that lead to the enhancement of the real part of the dynamic permeability to larger values and increases its maximum values relative to the case where the inner cylinder is absent. In addition, the Ohmic dissipation causes the damping of the amplitude of the response.

Trauma de colon: tendencia actual del tratamiento / Trauma of the colon: actual trends of treatment

Noventa y cinco pacientes con trauma colonico fueron recibidos en el Hospital de Caldas de Manizales, en el periodo comprendido entre febrero de 1997 y marzo de 1999; de estos, 74 (77.9 por ciento) presentaban criterios aceptados en la literatura mundial como condicionantes para la realizacion de colostomia, de los cuales fueron tratados con reparo primario 49 (66.2 por ciento), reseccion y anastomosis, 5 (6.7 por ciento), y con colostomia, 20 (27 por ciento). Treinta y un pacientes (41.8 por ciento) tenían un ATI mayor que 25; 72 (97.2 por ciento) presentaban un CIS CISFLINT de II y III; se presentaron episodios de shock en el 21 por ciento de los casos al ingreso, en 14.8 por ciento durante el acto quirurgico, y en el 8.1 por ciento de manera persistente; 17 (22.9 por ciento) pacientes tuvieron contaminacion fecal de manera moderada o severa, 54 por ciento de los traumas fueron tratados en un tiempo mayor a 6 horas; el 82.4 por ciento de los lesionados presentaba heridas asociadas al momenta de establecerse el tratamiento. Existieron complicaciones en el 35.1 por ciento de los pacientes tratados con reparo primario o reseccion y anastomosis, y en el 70 por ciento de los tratados con colostomia. En el grupo analizado se presentaron 2 dehiscencias, sin desenlace fatal. Con el apoyo de una regresion logistica se concluyo que, independientemente de los factores de riesgo asociados, el reparo primario o la reseccion y anastomosis deben ser las tecnicas de eleccion en los pacientes con trauma colonico, pues la evolucion es más favorable y con menos complicaciones asociadas y evita la necesidad de un segundo tiempo quirurgico, como ocurre en el caso de la colostomia.