393 research outputs found
Stream ambient noise, spectrum and propagation of sounds in the goby Padogobius martensii: Sound pressure and particle velocity
The most sensitive hearing and peak frequencies of courtship calls of the stream goby, Padogobius martensii, fall within a quiet window at around 100Hz in the ambient noise spectrum. Acoustic pressure was previously measured although Padogobius likely responds to particle motion. In this study a combination pressure (p) and particle velocity (u) detector was utilized to describe ambient noise of the habitat, the characteristics of the goby’s sounds and their attenuation with distance. The ambient noise (AN) spectrum is generally similar for p and u (including the quiet window at noisy locations), although the energy distribution of uspectrum is shifted up by 50–100Hz. The energy distribution of the goby’s sounds is similar for p and uspectra of the Tonal sound, whereas the pulse-train sound exhibits larger p–u differences. Transmission loss was high for sound p and u: energy decays 6–10dB∕10cm, and sound p∕u ratio does not change with distance from the source in the nearfield. The measurement of particle velocity of stream AN and P. martensiisounds indicates that this species is well adapted to communicate acoustically in a complex noisy shallow-water environment
Acoustic communication in two freshwater gobies: Ambient noise and short-range propagation in shallow streams
Noise is an important theoretical constraint on the evolution of signal form and sensory performance. In order to determine environmental constraints on the communication of two freshwater gobies Padogobius martensii and Gobius nigricans, numerous noise spectra weremeasured from quiet areas and ones adjacent to waterfalls and rapids in two shallow stony streams. Propagation of goby sounds and waterfall noise was also measured. A quiet window around 100 Hz is present in many noise spectra from noisy locations. The window lies between two noise sources, a low-frequency one attributed to turbulence, and a high-frequency one (200–500 Hz) attributed to bubble noise from water breaking the surface. Ambient noise from a waterfall (frequencies below 1 kHz) attenuates as much as 30 dB between 1 and 2 m, after which values are variable without further attenuation (i.e., buried in the noise floor). Similarly, courtship sounds of P. martensii attenuate as much as 30 dB between 5 and 50 cm. Since gobies are known to court in noisy as well as quiet locations in these streams, their acoustic communication system (sounds and auditory system) must be able to cope with short-range propagation dictated by shallow depths and ambient noise in noisy locations
Geologia dei Gessi di Brisighella e Rontana
L’area di Brisighella rappresenta un eccellente laboratorio naturale per comprendere la prima fase della crisi di salinità , lo straordinario evento geologico che nel Messiniano (Miocene superiore), tra 5.970.000 e 5.600.000 di anni fa, ha trasformato il bacino del Mediterraneo in una gigantesca salina inospitale per la maggior parte delle forme di vita. La crisi di salinità messiniana ha prodotto 16 strati di selenite della Vena del Gesso (Gessi Inferiori Primari) con cristalli lunghi fino a due metri che contengono fossilizzati al loro interno filamenti di cianobatteri. Appena terminata la deposizione del gesso l’area è stata coinvolta da importati eventi tettonici che hanno innescato enormi frane sottomarine provocando lo smembramento della formazione gessosa e la deposizione dei Gessi Inferiori Risedimentati.
Abstract
The Brisighella area is an excellent natural laboratory for understanding the first phase of the salinity crisis, the dramatic geological event that has turned the Mediterranean Sea into a giant salina inhospitable to most life forms during the Messinian (Upper Miocene), between 5.97 million and 5.6 million years ago. The Messinian salinity crisis has produced 16 layers of selenite Vena del Gesso (Primary Lower Gypsum) with crystals up to two meters tall containing fossilized filaments of cyanobacteria. As soon as the deposition of gypsum finished, the area has been affected by tectonic events that have triggered massive submarine landslides causing the dismantlement of the gypsum formation and the deposition of the Resedimented Lower Gypsum unit
High-frequency cyclicity in the Mediterranean Messinian evaporites: evidence for solar-lunar climate forcing
The deposition of varved sedimentary sequences is usually controlled by
climate conditions. The study of two Late Miocene evaporite successions (one
halite and the other gypsum) consisting of annual varves has been carried out
to reconstruct the paleoclimatic and paleoenvironmental conditions existing
during the acme of the Messinian salinity crisis, ~ 6 Ma, when thick evaporite
deposits accumulated on the floor of the Mediterranean basin. Spectral analyses
of these varved evaporitic successions reveal significant periodicity peaks at
around 3-5, 9, 11-13, 20-27 and 50-100 yr. A comparison with modern
precipitation data in the western Mediterranean shows that during the acme of
the Messinian salinity crisis the climate was not in a permanent evaporitic
stage, but in a dynamic situation where evaporite deposition was controlled by
quasi-periodic climate oscillations with similarity to modern analogs including
Quasi-Biennial Oscillation, El Ni\~no Southern Oscillation, and decadal to
secular lunar- and solar-induced cycles. Particularly we found a significant
quasi-decadal oscillation with a prominent 9-year peak that is commonly found
also in modern temperature records and is present in the contemporary Atlantic
Multidecadal Oscillation (AMO) index and Pacific Decadal Oscillation (PDO)
index. These cyclicities are common to both ancient and modern climate records
because they can be associated with solar and solar-lunar tidal cycles.Comment: 13 pages, 10 figures, 1 Tabl
The deep record of the Messinian salinity crisis: Evidence of a non-desiccated Mediterranean Sea
This research is focused on a complete reexamination of the evaporite facies present in all the cores that cut
through the topmost deposits of the Messinian salinity crisis lying below the floor of the Mediterranean Sea
(DSDP Legs 13 and 42A, ODP Legs 107 and 161). This review suggests that the uppermost evaporite units in
both western and eastern deep Mediterranean basins consist mainly of clastic (gypsrudite, gypsarenite and
gypsiltite) and fully subaqueous deposits (laminar gypsum, selenite and cumulate halite) that are partially
affected by burial anhydritization and tectonic induced recrystallization. No unequivocal evidence of shallow
water or even supratidal (sabkha) deposition is in evidence, suggesting that at the very last phase of the salinity
crisis the Mediterranean Sea did not experience desiccation, but that deposition took place under permanent
subaqueous conditions
La "selce dei Crivellari": appunti sulla silice (calcedonio, selce e quarzo) nella Vena del Gesso romagnola
L\u2019articolo prende spunto dalla caratteristica selce affiorante a nord est di M. Tondo (presso il borghetto dei Crivellari) per fare il punto delle conoscenzesulle manifestazioni silicee nella Vena del Gesso romagnola, evidenziandone sia la distribuzione disomogenea che la complessit\ue0 mineralogica. I principali litotipi descritti sono: calcedonio grigio (\u201cselce dei Crivellari\u201d), selce in calcare, selce laminata, quarzo dendritico e legno silicizzato.
Si ritiene che l\u2019ipotesi geochimica esposta da FORTI (1994) per spiegare la genesi a bassa temperatura del quarzo dendritico nella Grotta \u201cAzzali\u201d (Gessi di M. Mauro) fornisca un\u2019utile chiave interpretativa anche per le altre manifestazioni silicee rilevate. Si suggerisce inoltre che la localizzazione della silice, riscontrata esclusivamente nella porzione centro-orientale della Vena del Gesso, sia probabilmente legata al particolare assetto geometrico/strutturale che la dorsale manifesta in tale settore.
Abstract
This article illustrates the characteristic chert outcropping northeast of Mt. Tondo (near the Crivellari hamlet) and discusses the various siliceous rocks formed within the gypsum evaporites of the \u201cVena del Gesso\u201d(Romagna, Northern Apennines, Italy) highlighting their occurrence and mineralogical complexity. The main rock types described are: grey chalcedony (\u201cCrivellari chert\u201d), chert in limestone, laminated chert, dendritic quartz and silicified wood.
We suggests that the geochemical hypothesis proposed by FORTI (1994) to explain the origin of the low-temperature dendritic quartz of the \u201cAzzali Cave\u201d (near M. Mauro) provides a useful interpretative key also forthe other siliceous lithotype. We also suggest that exclusive occurrence of the silica in the central-eastern portion of the studied area the , is probably related to the particular geometrical/structural arrangement of the Vena del Gesso ridge
Draft Genome Sequence of the Carboxydotrophic Alphaproteobacterium Aminobacter carboxidus Type Strain DSM 1086
Aminobacter carboxidus is a soil Gram-negative alphaproteobacterium belonging to the physiological group of carboxydobacteria which aerobically oxidize CO to CO2 Here, we report the draft genome sequence of the A. carboxidus DSM 1086 type strain and the identification of both form I and form II CO dehydrogenase systems in this strain
A Facile and Efficient Protocol for Preparing Residual-Free Single-Walled Carbon Nanotube Films for Stable Sensing Applications
In this article, we report on an efficient post-treatment protocol for the manufacturing of
pristine single-walled carbon nanotube (SWCNT) films. To produce an ink for the deposition, the
SWCNTs are dispersed in an aqueous solution with the aid of a carboxymethyl cellulose (CMC)
derivative as the dispersing agent. On the basis of this SWCNT-ink, ultra-thin and uniform films are
then fabricated by spray-deposition using a commercial and fully automated robot. By means of X-ray
photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and scanning
electron microscopy (SEM), we show that the CMC matrix covering the CNTs can be fully removed
by an immersion treatment in HNO3 followed by thermal annealing at a moderate temperature
of 100 ºC, in the ambient air. We propose that the presented protocols for the ink preparation
and the post-deposition treatments can in future serve as a facile and efficient platform for the
fabrication of high-quality and residual-free SWCNT films. The purity of SWCNT films is of particular
importance for sensing applications, where residual-induced doping and dedoping processes distort
the contributions from the sensing specimen. To study the usability of the presented films for practical
applications, gas sensors are fabricated and characterized with the CNT-films as the sensing material,
screen printed silver-based films for the interdigitated electrode (IDE) structure, and polyimide as a
flexible and robust substrate. The sensors show a high and stable response of 11% to an ammonia
(NH3) test gas, at a concentration of 10 ppm.The authors thank the Deutsche Forschungsgemeinschaft (DFG) and the Natural Sciences and
Engineering Research Council (NSERC) for financial support of the Alberta/Technische Universität München
Graduate School for Functional Hybrid Materials ATUMS (IRTG2022, NSERC CREATE), as well as the TUM
Graduate School, the Nanosystems Initiative Munich (NIM), and the TUM International Graduate School of
Science and Engineering (IGSSE)
Genome sequence of Serratia marcescens phage BF
Phages infecting Serratia marcescens, a common causative agent of nosocomial infections, have potential therapeutic applications. Here, we report the complete genome of the novel S. marcescens phage BF, representing the third-largest phage genome sequenced to date
The Lactococcus lactis pan-plasmidome
Plasmids are autonomous, self-replicating, extrachromosomal genetic elements that are typically not essential for growth of their host. They may encode metabolic capabilities, which promote the maintenance of these genetic elements, and may allow adaption to specific ecological niches and consequently enhance survival. Genome sequencing of 16 Lactococcus lactis strains revealed the presence of 83 plasmids, including two megaplasmids. The limitations of Pacific Biosciences SMRT sequencing in detecting the total plasmid complement of lactococcal strains is examined, while a combined Illumina/SMRT sequencing approach is proposed to combat these issues. Comparative genome analysis of these plasmid sequences combined with other publicly available plasmid sequence data allowed the definition of the lactococcal plasmidome, and facilitated an investigation into (bio)technologically important plasmid-encoded traits such as conjugation, bacteriocin production, exopolysaccharide (EPS) production and (bacterio)phage resistance
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