Light Area Research Articles

Aspectos clínicos, ultrassonográficos e patológicos da tromboflebite iatrogênica em uma égua - relato de caso

ABSTRACT A 7-year-old quarter horse mare showed swelling of the tongue, head and neck region, dyspnea, and red urine after eight days of administration of intravenous medications by the animal's handler. The horse was referred to the University Veterinary Hospital of the Federal University of Pará and, at the clinical examination, showed apathy, edema in the head, neck, and tongue region, which was slightly cyanotic and with loss of epithelium in the dorsal region. The maxillary, linguofacial and external jugular veins were bilaterally engorged, firm to palpation and with cord-shaped appearance, with extension of the head to the entrance to the thoracic cavity. Ultrasound examination showed a thrombi with a hyperechoic and heterogeneous appearance that completely obstructed the vessel. The horse died five days after entering the Hospital and at necropsy it was observed: maxillary, linguofacial and external jugular veins bilaterally filled with firm, dark red to blackish thrombi; ulcerated areas in the final third of the esophagus and the stomach; lighter areas on the surface of the kidneys and dark areas at the corticomedullary junction. Based on clinical, ultrasonographic and necropsy findings, iatrogenic thrombophlebitis was diagnosed, associated with repeated injections of drugs administered intravenously.

Acidente ofídico em equinos no Bioma Amazônico, Pará, Brasil

ABSTRACT: Bothrops atrox is the most common viper in the Amazon, and its venom causes local and systemic changes. This report describes the clinicopathological and laboratory findings of ophidism due to Bothrops in six horses in Pará, Brazil. The animals, which belonged to five different rural properties, showed clinical signs of apathy, anorexia, and increased touch sensitivity in areas of increased volume. Three animals were bitten in the distal part of the pelvic limbs and three in the head area. The affected animals in the distal limb area exhibited marked edema extending from the fetlock to the thigh and had difficulty moving. Those affected in the head region exhibited an increase in volume that gave the appearance of a “rhinoceros head,” as well as blackening of the mucosa of the lips and gums. All animals exhibited tachycardia and tachypnea, and laboratory findings of two animals showed anemia, leukocytosis, increased clotting time, and elevated liver (AST and GGT) and kidney enzymes (urea and creatinine). Treatment was ineffective, and three of four treated animals died. Necropsy was performed on three animals, revealing extensive hemorrhage in the tissues at the snake bite sites and incoagulable bloody fluid in the cavities. Congestion was observed in the diaphragm, in the serosa of the small intestine, and in lighter areas on the renal surface. Histopathology showed muscle degeneration, necrosis, acute tubular necrosis, hemorrhage, and hyaline casts in the kidneys. This case report highlights the clinicopathological findings of snakebite in horses. In addition, this seems to be the first report of bothropic envenom in a mule in Brazil.

Non-Invasive Study of the Pigments of a Painting on Copper with the Inscription “Boceto di Pablo Veronese” on the Back

The palette used on a small painting on copper support, with the inscription “Boceto di Pablo Veronese” on the back, was characterized. Non-invasive techniques such as X-ray diffraction (XRD) and hand-held X-ray fluorescence (XRF) were proven to be highly effective for this. The objectives of the proposed work were twofold. On the one hand, the objective was the study, in situ, of the pigments of a painting on a copper support. On the other hand, it was to enrich the literature related to the study of paintings on metal supports, since few related studies are available despite the relatively large number of such 16th and 17th century paintings from Italy and Northern Europe. The results of the analysis showed a copper support with a base layer of gypsum mixed with ochre earths. Atop this layer is a sketch with lead white in the lighter areas and bone black in the darker shadow areas, suggesting that the artist performed a preliminary study of the luminosity of the scene. Finally, the upper or pictorial layer consists of a mix of pigments with some lead white to lower saturation and increase lightness, particularly evident in the flesh tones. The resulting palette thus includes lead white, vermilion, bone black, Naples yellow, and lazurite pigments. These results are compared to Veronese’s other paintings, as well as to those of certain contemporary artists, and the use of the resulting pigments in 16th and 17th century Italian painting techniques is discussed.

Ghosting phenomenon in static and dynamic footprints in India and the United States

Ghosting is the phenomenon that exists when a footprint has a lighter area around the tip of one or more toes or a shadow-like area at the back of the heel. To date, ghosting has been considered primarily a finding of dynamic (walking) footprints, rather than static (standing) footprints. The prevalence of ghosting in static footprints is unknown, and research on its presence in static and dynamic footprints from the same participant is sparse, as are studies on its occurrence in different geographic populations. This study is among the first to evaluate the occurrence of ghosting in the static and dynamic footprints from a particular individual with participants in two geographic populations.A combination of both inkless and ink footprint collection systems were used to obtain a total of 206 bare footprints from 103 adult participants from the United States and India. The data comprised 103 static and 103 dynamic footprints.Ghosting occurred significantly in static footprints, though less frequently than in dynamic footprints. Ghosting in static footprints was seen most often at the first toe, followed by the third and second respectively. This aspect appeared least at the heel. In dynamic footprints, it occurred most at the first toe, followed by the second and fourth toes, and then the third toe and the heel. The prevalence of ghosting in footprints from the United States and India differed in their locations, notably at the first and second toes in the static footprints and at the heel in the dynamic footprints.

SnO2–Fe3O4 nanocomposites for the photodegradation of the Congo red dye

Synthesis of SnO2–Fe3O4 nanocomposites was conducted. The purpose of this study was to obtain the SnO2–Fe3O4 nanocomposites, the effectiveness of photodegradation Congo red by SnO2–Fe3O4 nanocomposites and determine the kinetics of photodegradation. The XRD analysis showed that the SnO2–Fe3O4 nanocomposite best mass ratio was 1:1 based on the highest intensity of characteristic angle (2θ), which is 26.54° and had the smallest crystal size, which is 9.662 nm. Based on the UV-Vis DRS result, the SnO2–Fe3O4 nanocomposites bandgap value was 2.3 eV. The magnetization saturation value of SnO2–Fe3O4 nanocomposites was 64.96 emu/g. The morphology of SnO2–Fe3O4 nanocomposites showed by the TEM image, where the dark spots spread in the lighter areas. The surface of SnO2–Fe3O4 nanocomposites characterized by SEM with the result was bumpy surface and many pores. The EDS result of SnO2–Fe3O4 nanocomposites confirmed the presence of Fe, Sn, and O elements. The functional group of SnO2–Fe3O4 nanocomposites showed by FTIR data, the stretch band of Sn–O characteristics showed at wavenumber 590 cm−1, and the stretch band of Fe–O showed at wavenumber 563 cm−1. The optimum condition of nanocomposites at a contact time of 90 min and the optimum concentration of 18 mg/L showed that the percent of photodegradation was 50.76%. The photodegradation rate of SnO2–Fe3O4 was fitted to Pseudo-second-order.

Genesis of monazite-rich, orthopyroxene-bearing veins in the Kliphoog area of the Concordia Granite, Springbok, Namaqualand, South Africa: Sources, fluids, and the mobility of actinides and REE

A network of monazite-rich, coarse-grained veins and fine-grained veins permeating the mid-Proterozoic Concordia Granite in the Kliphoog area near Springbok, Namaqualand, North Cape Province, South Africa, are described with respect to their whole-rock chemistry, petrography, mineralogy, and mineral chemistry along with zircon and monazite geochronology. Chondrite-normalized trace element data indicate that the coarse-grained veins are enriched in LREE relative to the Concordia Granite with HREE enrichment being somewhat variable. HREE in altered Concordia Granite, at the contact with the coarse-grained vein, are heavily depleted compared to unaltered Concordia Granite while the LREE show the same approximate abundances. Chloritization is common in the coarse-grained veins along mineral grain boundaries with chlorite replacing most of the orthopyroxene megacrysts, though occasional remnants of orthopyroxene remain in the core. A traverse across one of the coarse-grained veins showed no obvious mineral chemical trends between the vein and surrounding granite. Relic Fe-rich megacryst orthopyroxene has an Al2O3 content of around 2.0 wt% suggesting formation at around 700 °C. The Fe-rich biotite has mean Ti values ranging from TiO2 = 4.1 to 1.2 wt% indicating formation at 700–800 °C. The coarse-grained veins and fine-grained veins are characterized by abundant accessory Th-rich monazite, heterogeneously distributed in the veins. Lesser amounts of monazite are found in the granite. Other accessory minerals in the veins and granite include zircon and rare fluorapatite. Back-scattered electron imaging shows that the anhedral to euhedral monazite grains (up to more than 1500 μm in size) tend to be complexly zoned with light and dark areas. Lighter areas are more enriched in Th and/or Ce than darker areas. This complex zoning can occur as magmatic/sector zoning and more commonly as a complex series of metasomatic alteration events. Metasomatic textures, which are due to variable fluid-induced mobility of Th, U, and REE, are the result of a coupled dissolution-reprecipitation process and have been reproduced experimentally using high pH alkali-bearing fluids. The analysis of seven zircon cores from the Concordia Granite yields a concordia age of 1173 ± 15 Ma suggesting that an age of ca. 1170 Ma most likely represents the true emplacement age of the Concordia Granite. The mean 207Pb/206Pb age of 1042 ± 9 Ma obtained on zircon from the main coarse-grained vein is interpreted as the crystallization age of the vein. 207Pb/235U monazite ages are highly variable in the veins and Concordia Granite host, ranging from ca. 1050 to 1000 Ma. This supports the petrographic and mineral chemistry evidence that the monazite U--Pb system was variably affected by a continuous or multi-pulse metasomatic/metamorphic event(s) occurring between 1050 and 1000 Ma. U--Pb analyses of deformed monazite crystals from a radioactive sinistral shear zone of the Kliphoog area yield a mean 207Pb/235U age of ca. 1006 ± 9 Ma, indicating that the late circulation of Th-LREE-rich fluids synchronous with strike-slip deformation occurred at ca. 1000 Ma. On a regional scale, the intrusion of the Kliphoog coarse-grained vein is contemporaneous with granulite-facies metamorphism as well as the A-type granitoid magmatism of the Spektakel Suite, mafic magmatism of the Koperberg Suite, and emplacement of the monazite vein-type deposit at Steenkampskraal. Therefore, a genetic relationship between the formation of monazite-rich Kliphoog veins and these metamorphic, magmatic, and metallogenic events is proposed.

Application of Luojia 1-01 Nighttime Images for Detecting the Light Changes for the 2019 Spring Festival in Western Cities, China

This study analyzed changes in nighttime light during the 2019 Spring Festival using Luojia 1-01 nighttime images in six western cities of China (Chengdu, Panzhihua, Kunming, Yuxi, Lhasa, and Jinchang). First, the radiance of the nighttime images was calculated. Second, the light area (LA) and average light intensity (ALI) were estimated for both Spring Festival and non-festival dates. Third, the differences in LA and ALI between the Spring Festival and non-festival were analyzed for all six cities. Migration population data from Baidu Inc. were used to examine the relationship between the changes of nighttime light and the population migration. The results show that, during the non-festival to Spring Festival period, the decrease in LA values coincided with negative net immigration. During the Spring Festival to non-festival period, the LA values increased, which coincided with positive net immigration. The F-test shows that the positive linear relationship between the normalized change in LA and the normalized net immigration is significant at the 0.05 level. This strongly indicates that population migration causes changes in LA. Moreover, while the population is considerably less in these cities during the Spring Festival, the ALI is noticeably higher, which suggests that urban activities are intensified during this period. This study demonstrates the applicability of using Luojia 1-01 nighttime images to detect the nighttime light changes for the Spring Festival in western cities, China, which can then be used to evaluate population migration and urban activities in the Spring Festival. Considering the higher spatial resolution of Luojia 1-01 than NPP (National Polar-orbiting Partnership) / VIIRS (Visible infrared Imaging Radiometer), this study may inspire more applications of Luojia 1-01 to track the activities in a variety of festival-cultures and cities.

Stop the global slaughter of sharks

The unsustainable slaughter of millions of sharks for their fins continues unabated even in EU waters, threatening the survival of several species. Meanwhile, new discoveries about the ecology of the top predators illustrate how much we still have to learn about the life we are about to destroy. Michael Gross reports.

Giant Congenital Melanocytic Nevus (GCMN) - A New Hope for Targeted Therapy?

We present a 6-month-old male patient, who was consulted with dermatologist by his parents, because of a pigmented lesion, present since birth, covering almost the all skin of the back and buttocks. A sharply bordered, unequally coloured congenital pigmented nevus, measuring approximately 21 cm in diameter was observed in the whole body skin examination. The lesion was affecting the lower 2/3 of the skin of the back and the top half of the gluteus area, extending to the lateral part of the tors, forward the abdomen and the upper lateral part of the hips, composed by multiple darker-pigmented nests and several lighter areas, with single depigmented zones, hairy surface, irregularly infiltrated on palpation. Congenital melanocytic nevi are presented in approximately 1% of newborns, while giant congenital melanocytic nevi (GCMN) are the most uncommon subtype of them; with occurrence rate 1 in 50,000 births. They affect 2% of a total body surface or presenting in a diameter larger than 20 cm in older children. Although not common, the possible malignant transformation remains one of the most important considerations related to them, as the related lifetime risk of melanoma is 4% to 10%. Treatment recommendations include non-surgical methods as dermabrasion only within the first two weeks of life, for prevention the possible melanocytic deeper migration, while serial surgical excisions or tissue expanders could be useful treatment tool even in later stages. Nevertheless, cosmetic result is not always satisfactory, and the risk of malignant changes remains, in cases of previous melanocytic migration in deeper layer. Recent article suggests the potential role in the treatment of GCMN with NRAS inhibitor trametinib, approved for treatment of advanced melanoma, associated with underlying NRAS mutations. Although promising, the drug could be useful in paediatric patients, only with associated NRAS gene mutation. It is still unclear whether it could be helpful, independent of the NRAS status.

These lit areas are undeveloped: Delimiting China’s urban extents from thresholded nighttime light imagery

Nighttime light imagery is a powerful tool to study urbanization because it can provide a uniform metric, lit area, to delimit urban extents. However, lit area is much larger than actual urban area, so thresholds of digital number (DN) values are usually needed to reduce the lit area. The threshold varies greatly among different regions, but at present it is still not very clear what factors impact the changes of the threshold. In this study, urban extent by province for China is mapped using official statistical data and four intercalibrated and geometrically corrected nighttime light images between 2004 and 2010. Lit area in the imagery for most provinces is at least 94% greater than the official amount of urban area. Regression analyses show a significant correlation between optimal thresholds and GDP per capita, and larger thresholds more commonly indicate higher economic level. Size and environmental condition may explain a province’s threshold that is disproportionate to GDP. Findings indicate one threshold DN is not appropriate for multiple (adjacent) province urban extent mapping, and optimal thresholds for one year may be notably different than the next. Province-level derived thresholds are not appropriate for other geographic levels. Brightness of nighttime lights is an advantage over imagery that relies on daylight reflection, and decreases in brightness indicate faster growth in the horizontal direction than the vertical. A province’s optimal threshold does not always maintain an increase with population and economic growth. In the economically developed eastern provinces, urban population densities decreased (and this is seen in the brightness data), while urban population increased.

COLOR CONCEPTS IN WARDROBE PLANNING

Fashion trends point out colors to wear but individuality should never be overlooked An impression of fine colors in dress will be gained if they are becoming to the person who is to wear them, if they are right for the occasion and if they are selected and arranged so as to make a pleasing ensemble.The larger the area the duller a color should be specially for business wear, but foe an evening or sports wear, it should be modified. The colors should be bright then, provided the wearer is not too large.The colors, in a costume, should be so distributed that a balance is achieved. When the top is light, the other part may be dark but the darkness should be present in the lighter area as a contrast. One should always keep in mind that the wearer should be the centre of interest and the costume a background.In order that the costume may be beautiful its color should be balanced or keyed and the entire color scheme should be related to the coloring of the individual.The aim in choosing colors for individual types should be to select those which will bring out the persons best points and subdue the less attractive ones.

Sidebearings analysis of alphabet letters with complex shape

Defining inter-letter space is important part of typeface designing process. The purpose of defining the letter space is to make them visually equally distant from each other within words, sentences and paragraphs creating an even value of grey, without darker or lighter areas. Different approaches for determining letter space were developed in order to facilitate this demanding process. Miguel Sousa (2006) and Walter Tracy (2003) proposes their spacing methods and in paper of De Melo Vargas (2007) and our previous work (Banjanin & Nedeljković, 2014) these methods were tested. The problems occur when defining space around letters a, f, g, s, t, z, and S, for which neither Sousa nor Tracy propose any kind of guidelines (except visual). The aim of this paper is to measure and analyse spacing values for these letters and to see if there is some kind of “formula” or some kind of guidelines which will broaden existing methods in more accurate way. We measured left and right sidebearings of these 7 problematic letters and established additional guidelines for defining letter space of those letters more accurately.

The Behavioral Preferences and Performance of Female Broilers under Unevenly Distributed Yellow LED Lights with Various Intensities

<abstract> <bold><sc>Abstract.</sc></bold> Light-emitting diode (LED) light sources show a high potential for replacing traditional incandescent lamps in broiler production facilities. LEDs offer clear advantages in energy efficiency. However, the application of LED technology to broiler production is restricted because of the absence of research about its uneven distribution of light intensity and subsequent impacts on broilers. This study investigated the effect of unevenly distributed yellow LED lights with different light intensities on the behavioral preferences and performance characteristics of female broilers. Four pens were developed to provide two unevenly distributed lighting environments with maximum light intensities (MLIs) of 90 and 60 lx in a study including replicates. Each pen consisted of four subzones characterized by their light intensity, including three subzones of high intensity (HI), medium intensity (MI), and low intensity (LI) in the lighting area (LA) and one non-lighting area (NA). Thirty female broilers were reared in each pen and were free to eat, drink, and stay in any subzone. No significant difference between the 90 and 60 lx experimental groups was found in feed conversion ratio (FCR), body weight (BW), uniformity, or growth ratio. The birds in both groups tended to drink water (p < 0.05) in the LI and MI subzones during the first three weeks. The preference of the birds then shifted to the MI and HI subzones with the growth of the birds despite substantial fluctuations within replicates. In both groups, feed intake was less affected than water intake by the uneven distribution of light intensity. The birds showed a transient feeding preference for LI and HI at young and old ages, respectively. The video data demonstrated that the birds showed a diurnal preference for LI (<2 lx) and a nocturnal preference for MI. The daily overall results showed higher preferences for NA in both groups. The preference-based lighting regimes indicated that the birds need less lighting time during the daytime than the nighttime. This study can provide further knowledge about broilers’ performance and behavior patterns in LED lighting environments, thus providing reference information for the configuration of LED arrays in commercial poultry production.

Onychophagia and postorthodontic isolated gingival recession: Diagnosis and treatment

This clinical report describes the diagnosis and the management of isolated-type recession defects of complex etiology in 2 healthy postorthodontic patients. The lesions were confined to 1 mandibular incisor and were associated with an abnormal buccolingual inclination of the affected tooth despite a lingual retainer made with a round stainless steel twisted wire. After careful questioning, it was determined that the recession defects were indirect effects of habitual onychophagia. The concomitant fingernail-biting habit and the lingual bonded retainer led to the indirect development of bone dehiscence and, consequently, gingival recession.

Estimation of virtual water contained in international trade products using nighttime imagery

Freshwater that is consumed in the process of producing a commodity is called virtual water – it represents all water use contained in that commodity. In social systems, water resources can flow when commodities are traded from one region to another. Quantitative monitoring and assessing virtual water flow related to international trade products is an important issue to comprehensively understand the balance of global water resources. In this study we tested the potential of the Defense Meteorological Satellite Program's Operational Linescan System (DMSP-OLS) nighttime images in conjunction with the LandScan population dataset for estimation of virtual water contained in international trade products. Lit area (areal extent of night lights) and urban population were selected as proxies to estimate export virtual water (EVW), import virtual water (IVW), and traded virtual water (TVW) (summed EVW and IVW), respectively, on the national level. The results showed that IVW can be more accurately estimated than EVW regardless of lit area or urban population. Lit area is normally more appropriate for estimation of the virtual water of developed countries than those of developing countries, but urban population is more appropriate for estimation of the virtual water of developing countries than those of developed countries. Urban population is a better proxy than total population for estimations of virtual water. This study makes a negative finding in that there are relatively large underestimations for developed countries. Another negative finding is that neither lit area nor urban population can be used to estimate net import virtual water (NIVW).

Morphological and Geochemical Evidence of Eumelanin Preservation in the Feathers of the Early Cretaceous Bird, Gansus yumenensis

Recent studies have shown evidence for the preservation of colour in fossilized soft tissues by imaging melanosomes, melanin pigment containing organelles. This study combines geochemical analyses with morphological observations to investigate the preservation of melanosomes and melanin within feathers of the Early Cretaceous bird, Gansus yumenensis. Scanning electron microscopy reveals structures concordant with those previously identified as eumelanosomes within visually dark areas of the feathers but not in lighter areas or sedimentary matrices. Fourier transform infrared analyses show different spectra for the feathers and their matrices; melanic functional groups appear in the feather including carboxylic acid and ketone groups that are not seen in the matrix. When mapped, the carboxylic acid group absorption faithfully replicates the visually dark areas of the feathers. Electron Paramagnetic Resonance spectroscopy of one specimen demonstrates the presence of organic signals but proved too insensitive to resolve melanin. Pyrolysis gas chromatography mass spectrometry shows a similar distribution of aliphatic material within both feathers that are different from those of their respective matrices. In combination, these techniques strongly suggest that not only do the feathers contain endogenous organic material, but that both geochemical and morphological evidence supports the preservation of original eumelanic pigment residue.

Relationships Between Satellite Observed Lit Area and Water Footprints

Global water resources are vulnerable to depletion due to the increasing demand of an ever-increasing human population. A country’s water footprint is a measure of the total volume of water needed to produce the goods and services consumed by the country, including water originating beyond its own borders. The water footprint can be a critical indicator of global water resource use, but its practical application is hindered by a lack of comparable data across national boundaries. The purpose of this article is to test the applicability of the nighttime imagery products produced by the Defense Meteorological Satellite Program’s Operational Linescan System (DMSP-OLS) for the assessment of the global water footprint. To accomplish this purpose, the average areal extent of nighttime lighting (lit area) is calculated from 1997 to 2001. Next, lit area is regressed on the total water footprint for each country, as indicated by the Water Footprint Network (WFN), to estimate that country’s total water footprint using nighttime imagery. Model residuals are analyzed at the national scale to understand the appropriateness of nighttime imagery for assessing water consumption. Results indicate strong positive correlations between lit area and total water footprint (TWF), domestic water withdrawal (DWW), and industrial water consumption (IWC) at the national scale. Overall, the analyses reveal that the rate of agricultural water consumption to total water footprint (AWCR) and population density can affect the precision of estimates when lit area is selected as a proxy to estimate water footprints.

Like Royalty among Us

After viewing the works of the Oaxacan and Huichol peoples of Mexico, my leaning toward bold color found its home through the production of upclose-and-personal portraits of women created with patterned pieces. The challenge of presenting women’s faces through individually painted pieces intrigued me. I began by painting strips of paper with a wide variety of patterns from which to choose. After doing some pencil drawings of women’s faces, rather than shading with pencil, I numbered each area with a value, 0–4. The zeroes were the lightest areas, growing progressively darker up to four. I then matched and cut the patterns from light to dark, gluing them together like a jigsaw puzzle. After the head was completed, it was glued on to the canvas as one piece. Other media such as beads, feathers, and pieces of freehand crossstitch were added to complete the collages. I want the viewer to consider each woman: where is she from? What stories does she tell? How has her life experience been like or different from the observer’s? Each woman portrayed comes from a different area of the world. How has her culture infl uenced what she sees? We get a sense of mystery and wonder from these portraits. There are clues to the origins of the women in the titles, but the full story of the women is to be completed through the imagination of the viewer. The intent of the portraits is to portray powerful women of many circumstances. Sometimes the subtlety of their stories is drowned out in the clamor of instant headlines, but if we pay attention, we will fi nd that they exist Like Royalty among Us.

Pigmentary demarcation lines on the face in Saudi women

Pigmentary demarcation lines (PDL) are physiological abrupt transition lines between hyperpigmented skin and lighter areas. Recent evidence suggests that they involve the face. To survey facial PDL in Saudi females referred to general dermatology clinics for various complaints and determine any associated risks. Screening for facial lines was done in general dermatology clinics over a year. Whenever a patient was found to have facial PDL, a detailed questionnaire and examination were undertaken. Out of 1033 patients screened, 144 patients (14%) were found to have at least one of the facial PDLs. The median age of onset was 16 years. The most common line was F with 76 patients (53%). Family history was positive in 51 patients (35%). Facial PDL is a common and chronic pigmentary problem in Saudi women. It should be recognized and differentiated from other similar diseases like melasma. A significant proportion of patients have a milder presentation.

Why birds should communicate by dynamic optical signal patterns and not by the static signals perceived by man

The ability to fly is a prominent feature of birds. While the changes in morphological structures during motion are well-known, the dynamics of optical signals generated by the birds' plumage are hardly perceived. Most studies and illustrations focus on static situations, with birds perching, or flying with their wings constantly spread. But given birds' capability for active flight, two assumptions seem to be imperative: birds should show dynamic signal patterns alternating periodically with the wing-strokes; birds should rely much more on dynamic signalling than on static marking. When spreading and folding the wing (and tail) during active flight, markings contrasting to the rest of the feathers may generate a flashing signal. Contrast may be intensified by “framing”. Thus in a wing stripe that is periodically “unveiled” in flight, lighter areas may be “framed” by darker parts of the vanes or shafts. Perception of dynamic signals is hampered by their complexity because of changes in size, shape, and orientation during motion. The complete pattern may be visible for a few milliseconds only. Dynamic signals may be more conspicuous because of rapid switching on and off. The evolution of contrasting signal patterns may reduce the mechanical stability of feathers. Thus, selection should balance these costs against the benefits of the signal's efficiency. Birds have to be viewed in natural surroundings, on different levels, and in action. A quantitative approach to dynamic optical signals is still largely lacking. Although hidden to human eyes, dynamic signal patterns extending to the UV may be widespread among birds.