Blue Wave Research Articles

Effect of exposure to short-wavelength light on susceptibility to motion sickness

This randomized cross-over study tested the hypothesis that exposure to short-wavelength light induces symptoms of motion sickness (MS). The study participants were 28 healthy adults (14 women; mean age±SD, 25.96±3.11 years). Two stimuli oscillating within a range of 0.4-0.6 Hz were used to induce MS: a blue wave stimulus with short-wavelength light (460 nm) and a green wave stimulus with middle-wavelength light (555 nm). All participants were exposed to both stimuli throughout two separate periods. After a baseline period, participants were exposed to each stimulus three times for 4 min. The Simulator Sickness Questionnaire, a self-report checklist composed of three subscales (Oculomotor, Disorientation, and Nausea), heart rate variability, and electrogastrography were used to measure the degree of symptoms related to MS. A linear mixed-effects model was used for statistical analysis. The results showed significant main effects for Period (P<0.01), Color (P<0.01), and Time Point (P<0.01) scores on the Simulator Sickness Questionnaire Nausea subscale. A post-hoc test indicated that scores on the Nausea subscale were significantly higher after the third exposure to blue light than after the first and second exposures. The linear mixed-effects model showed significant main effects for Color (P<0.01) with respect to the normogastria/tachygastria ratio. These findings suggest that short-wavelength light induces symptoms of MS, especially gastrointestinal symptoms.

Adults of Lasioderma serricorne and Stegobium paniceum (Anobiidae: Coleoptera) Are Attracted to Ultraviolet (UV) Over Blue Light LEDs.

Two species, the cigarette beetle Lasioderma serricorne (F.) and the drugstore beetle Stegobium paniceum (L.), are particularly important stored-product pests because they damage dry food. A previous study showed that L. serricorne adults are attracted more to ultraviolet (UV) and blue light wave ranges more than others such as turquoise, green, yellow, red, and warm white. However, the previous study did not equalize the amounts of light. The study also evaluated the attractiveness by the numbers of L. serricorne individuals that were lured to LED lights in a small box in the laboratory. In some storehouses, damage by S. paniceum is more serious and establishment of an effective monitoring tool is required. Therefore, in the present study, attractions of these beetles to UV and blue light traps were compared to develop a tool to monitor the beetle pests. First, adult L. serricorne and S. paniceum beetles were provided with UV- and blue-LED panels whose light intensities were equalized in the laboratory, and the walking and flying paths of each adult were recorded and measured. As a result, adults were clearly attracted to the side of UV-LED panel by walking compared to the blue one. Second, we compared the numbers of cigarette beetles collected by sticky sheets that were set in the back of UV or blue-light LED traps in a real storehouse. The results showed that these beetles were significantly more attracted to UV than blue-light LED traps, indicating the UV-LED trap is a powerful tool to monitor these two pest species.

Near-infrared reflectance and autofluorescence imaging characteristics of choroidal nevi.

PurposeTo report near-infrared reflectance (NIR-R), near-infrared autofluorescence (NIR-AF) and blue wave autofluorescence (BW-AF) appearance of choroidal nevi using a confocal scanning laser ophthalmoscope (cSLO).Patients and methodsNIR-R, NIR-AF and BW-AF images of choroidal nevi were compared with color fundus photos (CF). Images were graded as hyperreflective if reflectance was much greater than background, hyporeflective if less than background, and isoreflective if the same as the background.ResultsForty-two nevi of 39 patients were imaged. When compared with CF, nevi could be identified on 95% (40/42) NIR-R images (95% CI: 83.5-99.3). On NIR-R 71% (30/42) demonstrated hyperreflectance and 24% (10/42) were hyporeflective. Hyperreflectivity was demonstrated in 96% (23/24) of NIR-AF images (95% CI: 79.1-99.9) and 34% (14/41) of BW-AF images (95% CI: 20.0-50.5). On NIR-R, 29/40 (73%) were apparently smaller in comparison with CF and 11/40 (28%) had the same area. A correlation was found between NIR-R and NIR-AF (P=0.02) but not with BW-AF (P=0.15).ConclusionsNevi can be visualized well using NIR-R and NIR-AF imaging modalities, but are less frequently visible using BW-AF. These changes may be related to melanin within the choroid or chronic changes of the overlying retinal pigment epithelium.

Thermo-physical rock properties and the impact of advancing hydrothermal alteration — A case study from the Tauhara geothermal field, New Zealand

The thermo-physical rock properties density, porosity, matrix permeability, thermal conductivity and specific heat capacity of 418 orientated rock plugs cut from 233 cores recovered from geothermal investigation wells THM12, THM13, THM14, THM17, THM18, THM19, and TH18 at the Tauhara geothermal field, New Zealand were measured and a statistical database was set up. The lithotype of each sample was classified, and the hydrothermal alteration rank and intensity was determined by optical microscopy. The hydrothermal clays (typically smectite, smectite–illite, illite) were analysed by the methylene blue dye adsorption test and short wave infrared spectroscopy.Investigated stratigraphic units are the Huka Falls Formation with its sub members upper, middle and lower Huka Falls Formation, the Wairora Formation, Spa Andesite and its associated breccias, and Racetrack rhyolite and its associated breccias. Lithotypes are clay-altered tuff and intercalated mudstone/siltstone (cap rock for the Tauhara geothermal system); tuffaceous sandstones, sedimentary and pyroclastic breccias and pumiceous ash tuff (reservoir-hosting units); and rhyolitic and andesitic lavas, and their associated breccias.The obtained rock property data indicate a common porosity range of 30% to 45% for sediments, volcaniclastics and lava breccias, an average of 10% for andesite lava, and 39% for rhyolite lava. Matrix permeability of mudstone, siltstone, breccias and lavas is commonly <1mD, while sandstone, tuff and brecciated lavas have two to three orders of magnitude higher permeabilities. Both porosity and permeability decrease with depth. Thermal conductivity decreases with increasing porosity, and is similar for most lithotypes (0.7Wm−1K−1 to 1Wm−1K−1), while lavas have higher values (0.9Wm−1K−1 to 1.4Wm−1K−1). Specific heat capacity is similar for all lithotypes (0.6kJkg−1K−1 to 0.8kJkg−1K−1).Advancing hydrothermal alteration decreases the porosity of sandstone and ash tuff, but has contrasting effects on permeability. Permeability of ash tuff increases by a few millidarcy, while it decreases up to multiple orders of magnitude for sandstone with advancing alteration. Thermal conductivity of ash tuff increases by about 25% with advancing hydrothermal alteration and triples for sandstone, while specific heat capacity remains rather stable.

Multimodality imaging in macular telangiectasia 2: A clue to its pathogenesis.

Macular telangiectasia type 2 also known as idiopathic perifoveal telangiectasia and juxtafoveolar retinal telangiectasis type 2A is an acquired bilateral neurodegenerative macular disease that manifests itself during the fifth or sixth decades of life. It is characterized by minimal dilatation of the parafoveal capillaries with graying of the retinal area involved, a lack of lipid exudation, right-angled retinal venules, refractile deposits in the superficial retina, hyperplasia of the retinal pigment epithelium, foveal atrophy, and subretinal neovascularization (SRNV). Our understanding of the disease has paralleled advances in multimodality imaging of the fundus. Optical coherence tomography (OCT) images typically demonstrate the presence of intraretinal hyporeflective spaces that are usually not related to retinal thickening or fluorescein leakage. The typical fluorescein angiographic (FA) finding is a deep intraretinal hyperfluorescent staining in the temporal parafoveal area. With time, the staining may involve the whole parafoveal area but does not extend to the center of the fovea. Long-term prognosis for central vision is poor, because of the development of SRNV or macular atrophy. Its pathogenesis remains unclear but multimodality imaging with FA, spectral domain OCT, adaptive optics, confocal blue reflectance and short wave fundus autofluorescence implicate Müller cells and macular pigment. Currently, there is no known treatment for this condition.

Blue tensor spectrum from particle production during inflation

We discuss a mechanism of particle production during inflation that can result in a blue gravitational wave (GW) spectrum, compatible with the BICEP2 result and with the r < 0.11 limit on the tensor-to-scalar ratio at the Planck pivot scale. The mechanism is based on the production of vector quanta from a rolling pseudo-scalar field. Both the vector and the pseudo-scalar are only gravitationally coupled to the inflaton, to keep the production of inflaton quanta at an unobservable level (the overproduction of non-gaussian scalar perturbations is a generic difficulty for mechanisms that aim to generate a visible GW signal from particle production during inflation). This mechanism can produce a detectable amount of GWs for any inflationary energy scale. The produced GWs are chiral and non-gaussian; both these aspects can be tested with large-scale polarization data (starting from Planck). We study how to reconstruct the pseudo-scalar potential from the GW spectrum.

High-resolution in vivo imaging of regimes of laser damage to the primate retina.

Purpose. To investigate fundamental mechanisms of regimes of laser induced damage to the retina and the morphological changes associated with the damage response. Methods. Varying grades of photothermal, photochemical, and photomechanical retinal laser damage were produced in eyes of eight cynomolgus monkeys. An adaptive optics confocal scanning laser ophthalmoscope and spectral domain optical coherence tomographer were combined to simultaneously collect complementary in vivo images of retinal laser damage during and following exposure. Baseline color fundus photography was performed to complement high-resolution imaging. Monkeys were perfused with 10% buffered formalin and eyes were enucleated for histological analysis. Results. Laser energies for visible retinal damage in this study were consistent with previously reported damage thresholds. Lesions were identified in OCT images that were not visible in direct ophthalmoscopic examination or fundus photos. Unique diagnostic characteristics, specific to each damage regime, were identified and associated with shape and localization of lesions to specific retinal layers. Previously undocumented retinal healing response to blue continuous wave laser exposure was recorded through a novel experimental methodology. Conclusion. This study revealed increased sensitivity of lesion detection and improved specificity to the laser of origin utilizing high-resolution imaging when compared to traditional ophthalmic imaging techniques in the retina.

Investigation regarding prevention of insufficiency fractures in children with severe cerebral palsy by Light-Emitting Diode (LED) irradiation.

Bone metabolism in children with severe fractures was examined, risk factors for fractures were characterized, and effects of LED (light-emitting diode) irradiation on the risk factors for fractures were investigated. Since insufficiency fracture in children with severe cerebral palsy can be caused without obvious external force in daily care, it is sometimes handled as a medical accident and can lead to a lawsuit. It is very important to explain the possibility of an insufficiency fracture to guardians before a fracture is caused. However, risk factors for fractures in bone metabolism has not been well investigated and preventive treatment of fractures have also not been established. Risk factors in bone metabolism were investigated in 14 cases of insufficiency fracture in children with severe cerebral palsy accompanied by akathisia in this study. Fractures were likely caused around 8 years old when children grew rapidly, and either IGF-1 or BAP showed low values in all cases. A group with LED irradiation consisting of 25 cases indicated a normal value of IGF-1 related to bone growth, BAP related to bone density and NTX/Cr. A case irradiated to LED for more than one month clearly showed normal bone metabolism compared with the change within a non irradiated group after one year. LED irradiation increased bone density and femur cortical bone thickness, and improved bone age. Adequate effects were not seen in two children at 14 years of age. The commercially available LED light bulbs that we used have a peak at 446-477 nm in the blue wave length, but also have second peaks at 574 nm in green, at 590 nm in yellow, and even 612 nm in orange and 660 nm in red are included. Although it is thought that such a variety of wave lengths might have a good influence on bone metabolism; exposure time and distance, number of regions, and time period irradiated to LED are important factors, since the LED power density is low (0.9 mW/m(2) with a 30 cm distance). Our results suggest that LED irradiation can be a phototherapy to activate human homeostasis.

Third-order nonlinear optical properties of chemically synthesized copper oxide nanosheets

Copper oxide (CuO) nanosheets were obtained by a quick-precipitation method using Cu(NO3)2 and NaOH in the presence of polyvinylpyrrolidone (PVP). Different sizes of CuO nanosheets were achieved by varying the PVP concentration. The crystal structure, morphology, and optical properties of the CuO nanosheets were characterized by X-ray diffraction, transmission electron microscopy, and diffuse reflectance spectroscopy. Higher PVP concentrations produced CuO nanosheets with enhanced crystalline structure, reduced particle size, and enlarged band gap. Nonlinear optical characteristics were examined by the Z-scan technique using a blue continuous wave laser beam operated at 405nm. Increased PVP concentration from 0.5wt% to 5wt% was found to increase the nonlinear refractive index from −2.157×10−11 to −5.495×10−11.

Catheter Ablation of an Unusual Decremental Accessory Pathway in the Left Coronary Cusp of the Aortic Valve Mimicking Outflow Tract Ventricular Tachycardia

The anatomic location of atrioventricular (AV) bypass tracts (or accessory pathways) is variable, but these generally traverse the tricuspid or mitral annulus and insert into the atrium and ventricle near the AV ring. There is only 1 case report of an accessory pathway ablated in the left coronary cusp (LCC),1 and this pathway had bidirectional conduction, was not decremental, and was associated with an orthodromic tachycardia. We report here the first case of an antegrade slowly conducting, decremental, accessory pathway that was also successfully ablated in the aortic LCC. This pathway generated antidromic tachycardia having a QRS morphology mimicking those seen in outflow tract ventricular tachycardia. A 42-year-old woman was evaluated for palpitations and presyncope for 2 years. These were commonly associated with shortness of breath and chest heaviness that would resolve spontaneously. Her baseline ECG was normal without ventricular preexcitation. Echocardiogram, coronary angiogram, and thyroid function were also unremarkable. On her third presentation to a hospital, a broad complex tachycardia was captured (representative 12-lead ECG shown in Figure 1). The cycle length was 480 ms, the QRS duration was 150 ms, and a left bundle branch morphology with a right inferior axis was noted. She was referred for ablation of suspected ventricular outflow tract tachycardia. Consent was obtained for mapping and ablation of this tachycardia. During placement of catheters, a spontaneous initiation of tachycardia occurred, which was noted to have 1:1 AV association. A quadripolar catheter was placed at the right ventricular apex and His bundle, with a decapolar catheter in the coronary sinus. During ventricular pacing, retrograde conduction occurred with a long ventriculoatrial interval. Tachycardia was readily initiated with ventricular premature beats showing retrograde decremental conduction (Figure 2). An antegradely conducting accessory pathway was noted during atrial pacing maneuvers. During delivery of premature atrial stimulations, shortening of …

Supercontinuum generation in web-like microstructure optical fiber

A novel web-like microstructure optical fiber (MOF) is fabricated which serves as a bundle of suspended submicron-thickness membranes as planar waveguides and their Y-type connection nodes as the secondary cores. The polarization dependent visible continuum coverage from 350 to 1 000 nm is generated from a 20-cm-long membrane of 0.55-μm-thickness pumped by 200-fs laser at 800 nm. We also obtain narrowband signal of blue dispersive wave around 410 nm with the up-conversion efficiency routinely beyond 20% in the Y-type secondary core in another smaller web-like MOF.

Electrical Conducting Diamond Thin-Films: An Alternative Counter Electrode Material for Dye Sensitized Solar Cells

ABSTRACTCarbon is a favorable alternative as counter electrode material for dye sensitized solar cells (DSSC) as compared to Pt. Various carbon materials such as carbon nanotubes (CNT), activated carbon (AC) and carbon nanofibers have been investigated as counter electrodes for DSSC applications, based on their high electrochemical activity, high specific surface area, chemical inertness and high electrical conductivity. Among various phases of carbon, diamond is the most robust and chemical inert material that can be used for electrode application. It has band gap of 5.5 eV, high thermal conductivity. its electrical resistivity can be tuned by doping such as boron. In this work, we investigate boron doped diamond thin film electrode for DSSCs. The conductive diamond thin electrode films were grown using Blue Wave hot wire chemical vapor deposition (HWCVD) system. The electrical resistance in diamond thin films was tuned by controlling grow temperature, filament power, dopant concentration and sp3/sp2 ratio in the film, it thickness, and initial seeding process. Scanning electron microscopy, Raman spectroscopy and electrical resistivity measurement were used to characterize morphology, diamond quality and electrode conductivity, respectively. Diamond film electrodes with optimized surface morphology and electrical characteristics were used for DSSC fabrication. We used nanocrystalline TiO2 paste (P25 Degussa) with average particle size of 25nm as an active layer, the electrolyte comprised of a LiI/I2 electrolyte in acetonitrile (CH3CN), a Ru based metal complex dye [cis-diisothiocyanato-bis(2,2’-bipyridyl-4,4’-dicarboxylato) ruthenium(II) bis(tetrabutylammonium)] OR N719 was used as sensitizer. The photovoltaic performance was determined using J-V characteristics under standard illumination conditions and was compared to a reference DSSC with Pt counter electrode. Results are discussed in the context of diamond electrical and durability and chemical stability of diamond films against most commonly used family of iodine based electrolytes.

Blue Luminescence of ZnO Nanoparticles Based on Non‐Equilibrium Processes: Defect Origins and Emission Controls

AbstractHigh concentrations of defects are introduced into nanoscale ZnO through non‐equilibrium processes and resultant blue emissions are comprehensively analyzed, focusing on defect origins and broad controls. Some ZnO nanoparticles exhibit very strong blue emissions, the intensity of which first increase and then decrease with annealing. These visible emissions exhibit strong and interesting excitation dependences: 1) the optimal excitation energy for blue emissions is near the bandgap energy, but the effective excitation can obviously be lower, even 420 nm (2.95 eV &lt; Eg = 3.26 eV); in contrast, green emissions can be excited only by energies larger than the bandgap energy; and, 2) there are several fixed emitting wavelengths at 415, 440, 455 and 488 nm in the blue wave band, which exhibit considerable stability in different excitation and annealing conditions. Mechanisms for blue emissions from ZnO are proposed with interstitial‐zinc‐related defect levels as initial states. EPR spectra reveal the predominance of interstitial zinc in as‐prepared samples, and the evolutions of coexisting interstitial zinc and oxygen vacancies with annealing. Furthermore, good controllability of visible emissions is achieved, including the co‐emission of blue and green emissions and peak adjustment from blue to yellow.

Dramatic excitation dependence of strong and stable blue luminescence of ZnO hollow nanoparticles

Strong and stable blue luminescence was obtained from ZnO hollow nanoparticles. Significantly, dramatic excitation dependence was observed for blue emissions of ZnO: (1) band-gap energy (Eg) is the optimal excitation energy but smaller energies are still effective; (2) there exist several fixed emitting wavelengths in blue wave band, such as 412, 439, and 458 nm. These phenomena, combined with previously reported defect levels and formation thermodynamics, point out that the initial states of corresponding transitions to blue emissions could be zinc interstitials-related defect states, which were further verified by subsequent electron paramagnetic resonance examinations.

Success of science-based best management practices in reducing swimming bans—a case study from Racine, Wisconsin, USA

The Great Lakes region possesses over 10,000 miles of shoreline (US EPA and Government of Canada, 1995) which are home to over 1,000 beaches. These beaches represent a recreational outlet for over 30 million people (US EPA and Government of Canada, 1995) and yet many of them remain inaccessible for periods of time each bathing season due to water quality advisories. The reason for these advisories is often elusive to beach managers, hence impeding their ability to craft appropriate mitigation measures. Even when the sources of contamination are known, remediation measures may not be put into practice due to the perception that they are too costly. However, a recent study has demonstrated that investing in environmental improvements which increase the number of days available for swimming in the Great Lakes region by 20% would generate $2–$3 billion dollars in direct economic effects. Therefore, while beach closings and advisories continue to rise overall, some Great Lakes communities have recognized the potential for municipal beaches to generate revenue and increase the quality of life for their citizens and have undertaken comprehensive studies to improve recreational water quality. In Racine, Wisconsin, USA, research conducted to identify pollution sources guided the development of better beach management practices such as ecologically appropriate beach modifications, improved mechanical beach grooming strategies, and the redesign of a major storm water outlet (including installation of a constructed wetland area). Resulting improvements have reduced bathing water quality advisories from 66% of days during the swimming season in 2000 to 5% or less in four consecutive years (2005–2008). These improvements to Racine beaches facilitated Blue Wave certification from the Clean Beaches Council (Washington, DC); thereby restoring public confidence, increasing beach use by the residents and tourists, and expanding the role of the beachfront in the local economy.

Optical switching with cold atoms

At room temperature and atmospheric pressure, atoms travel hundreds of meters per second and collide frequently with one another and their surroundings. Although this unceasing thermal motion keeps us warm, it causes serious problems for anyone trying to probe the internal state of an atom. To reduce the deleterious effects of atomic motion, experimentalists often rely on optical fields to trap and cool atoms [1]. In a paper appearing in Physical Review Letters[2], Michal Bajscy and colleagues at the Harvard-MIT Center for Ultracold Atoms demonstrate a system that is capable of trapping and cooling atoms and shuffling them into the tiny core of a hollow optical fiber (Fig. 1) The confined atoms are then in prime position to interact with beams of light guided by the fiber. This simultaneous confinement of light and atoms leads to increased optical nonlinearities with which the Harvard group can create an all-optical switch: a few hundred photons are capable of controlling the transmission of a weak (∼ 1 pW) probe beam. In a prototypical quantum information system, single photons transmit information. The control of one photon by another is typically mediated by a nonlinear interaction with atoms [3, 4] and for this light-matter coupling to be strong requires a long interaction length and a high optical intensity. An optical beam in free space can only remain focused for a distance on the order of the Rayleigh range, given by zR = πw2 0/λ, where λ is the wavelength of light and w0 is the narrowest radial size of the beam. This relationship shows that a large interaction length (large zR) and a high intensity (small w0) are not simultaneously possible with focused beams in free space. Waveguides, such as optical fibers, offer a straightforward way to increase both the interaction length and the optical intensity. The challenge for designing a quantum information system is therefore to combine a microscopic waveguide with a medium that exhibits large optical nonlinearities. Photonic crystal fibers are a type of optical fiber where FIG. 1: Rubidium atoms are loaded into and trapped within a hollow-core photonic crystal fiber. A cross section of the hollow fiber is shown in the upper right. A dipole trapping beam (large red arrow) serves to localize the atoms (red, not drawn to scale) within the hollow core of the fiber. Additional probe, coupling, and switch fields (red, green, and blue wave packets, respectively) can then control the atomic state and implement all-optical switching and electromagnetically induced transparency. The relevant atomic levels are indicated as states |1〉, |2〉, |3〉, and |4〉 in the upper left. Note: the actual experimental orientation of the fiber is vertical to enable loading from a magneto-optical trap (not shown). (Illustration: Alan Stonebraker)

Characterization of arylalkylamine N-acetyltransferase (AANAT) activities and action spectrum for suppression in the band-legged cricket, Dianemobius nigrofasciatus (Orthoptera: Gryllidae)

Arylalkylamine N-acetyltransferase (AANAT), constituting a large family of enzymes, catalyzes the transacetylation from acetyl-CoA to monoamine substrates, although homology among species is not very high. AANAT in vertebrates is photosensitive and mediates circadian regulation. Here, we analyzed AANAT of the cricket, Dianemobius nigrofasciatus. The central nervous system contained AANAT activity. The optimum pHs were 6.0 (a minor peak) and 10.5 (a major peak) with crude enzyme solution. We analyzed the kinetics at pH 10.5 using the sample containing collective AANAT activities, which we term AANAT. Lineweaver-Burk plot and secondary plot yielded a K(m) for tryptamine as substrate of 0.42 microM, and a V(max) of 9.39 nmol/mg protein/min. The apparent K(m) for acetyl-CoA was 59.9 microM and the V(max) was 8.14 nmol/mg protein/min. AANAT of D. nigrofasciatus was light-sensitive. The activity was higher at night-time than at day-time as in vertebrates. To investigate most effective wavelengths on AANAT activity, a series of monochromatic lights was applied (350, 400, 450, 500, 550, 600 and 650 nm). AANAT showed the highest sensitivity to around 450 nm and 550 nm. 450 nm light was more effective than 550 nm light. Therefore, the most effective light affecting AANAT activity is blue light, which corresponds to the absorption spectrum of blue wave (BW)-opsin.

‘The Assyrian came down like the wolf on the fold, And his cohorts were gleaming in purple and gold; And the sheen of their spears was like stars on the sea, When the blue wave rolls nightly on deep Galilee’.

The Assyrian came down like the wolf on the fold, And his cohorts were gleaming in purple and gold; And the sheen of their spears was like stars on the sea, When the blue wave rolls nightly on deep Galilee’. -

Bio-optical properties and ocean color algorithms for coastal waters influenced by the Mississippi River during a cold front

During the passage of a cold front in March 2002, bio-optical properties examined in coastal waters impacted by the Mississippi River indicated that westward advective flows and increasing river discharge containing high concentrations of nonalgal particles contributed significantly to surface optical variability. A comparison of seasonal data from three cruises indicated spectral models of absorption and scattering to be generally consistent with other coastal environments, while their parameterization in terms of chlorophyll (Chl) alpha concentration showed seasonal variability. The exponential slope of the colored dissolved organic matter (CDOM) averaged 0.0161+/-0.00054 nm(-1) and nonalgal absorption averaged 0.011 nm(-1) with deviations from general trends observed due to anomalous water properties. Although the phytoplankton specific absorption coefficients varied over a wide range [0.02 to 0.1 m2 (mg Chl)(-1) at 443 nm] being higher in offshore surface waters, values of phytoplankton absorption spectra at the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) wave bands were highly correlated to modeled values. Particulate scattering characteristics were similar to observations for other coastal waters, while backscattering ratios were on average lower in phytoplankton-dominated surface waters (0.011+/-0.003) and higher in low Chl near-bottom waters (0.0191+/-0.0045). Average percent differences in remote sensing reflectance Rrs derived from modeled and in-water radiometric measurements were highest in the blue wave bands (52%) and at locations with more stratified water columns. SeaWiFS estimates of Chl and CDOM absorption derived using regional empirical algorithms were highly correlated to in situ data.

Temporal-spatial variations of euphotic depth of typical lake regions in Lake Taihu and its ecological environmental significance

By using the data of underwater irradiance measured in the different lake regions of Lake Taihu during 1998-2004 and total suspended solids (TSS), wind speeds of the total 13 stations in typical lake regions during 1993-2003, this paper analyzes the factors of influencing on PAR (pho- tosynthetically available radiation) attenuation, euphotic depth, and presents the temporal and spatial variations of euphotic depth of typical lake regions in Lake Taihu, and the spectral distributions of euphotic depth at station 2. The results show that the concentration of TSS is the most important factor impacting PAR attenuation, followed by chlorophyll a; chromophoric dissolved organic matter (CDOM) has little impact on the PAR euphotic depth. During 1993-2003, the mean yearly PAR eu- photic depths of the typical lake regions ranged from 1.04 to 1.95 m with a mean value of 1.35±0.23 m. The PAR euphotic depth fell into 3 spatial zone types: Type I, the lowest, including the lake center and the inflows of rivers; Type II, intermediate, including Meiliang Bay, Wulihu Lake and Gonghu Bay; Type III, the greatest, including the East Lake Taihu; corresponding mean depths were approximately 1.1, 1.4, 2.0 m, respectively. The seasonal variations of euphotic depths were not quite the same in different lake regions. In the lake center, the mean values of PAR euphotic depth in summer and au- tumn were significantly greater than those in winter and spring; in the Meiliang Bay, winter means were significantly greater than in the other three seasons; in the East Lake Taihu, winter means were significantly less than in the other three seasons. However, no distinct seasonal change was recorded in the Wulihu Lake, Gonghu Bay and the inflows of rivers. The spectral distributions of euphotic depth present a minimal value at the blue light wave band of 400 nm, and a peak at the green light wave band of around 580 nm. In 1998 and 1999, based on the seasonal many-day continuous measure- ments, the PAR euphotic depths at station 2 were recorded 2.00±0.21, 2.52±0.45, 1.58±0.24, 2.00 ±0.15 m in spring, summer, autumn and winter, respectively. The peak value of 440 nm absorbed by phytoplankton corresponded to a euphotic depth of only 0.81-1.47 m (mean 1.07±0.29 m), which was much lower than the mean PAR euphotic depth of 1.98±0.41 m.