3356 research outputs found
Sort by
KOS SEBAGAI MEDIATOR DALAM HUBUNGAN ANTARA PELATIH DAN PRESTASI PEKERJA UNTUK SEKTOR PERBANKAN PALESTIN
No full textPENCIRIAN STRAIN BAKTERIA GRAM-NEGATIF OPORTUNISTIK YANG DIPENCILKAN DARIPADA PESAKIT UNIT PENJAGAAN INTENSIF DI RIYADH, ARAB SAUDI
No full textEf?cient 3D real-time adaptive AUV sampling of a river plume front
No full textThe coastal environment faces multiple challenges due to climate change and human activities. Sustainable marine resource management necessitates knowledge, and development of ef?cient ocean sampling approaches is increasingly important for understanding the ocean processes. Currents, winds, and freshwater runoff make ocean variables such as salinity very heterogeneous, and standard statistical models can be unreasonable for describing such complex environments. We employ a class of Gaussian Markov random ?elds that learns complex spatial dependencies and variability from numerical ocean model data. The suggested model further bene?ts from fast computations using sparse matrices, and this facilitates real-time model updating and adaptive sampling routines on an autonomous underwater vehicle. To justify our approach, we compare its performance in a simulation experiment with a similar approach using a more standard statisticalmodel.Weshowthatoursuggestedmodelingframework outperforms the current state of the art for modeling such spatial ?elds. Then, the approach is tested in a ?eld experiment using two autonomous underwater vehicles for characterizing the three-dimensional fresh-/ saltwater front in the sea outside Trondheim, Norway. One vehicle is running an adaptive path planning algorithm while the other runs a preprogrammed path. The objective of adaptive sampling is to reduce the variance of the excursion set to classify freshwater and more saline fjord water masses. Results show that the adaptive strategy conducts effective sampling of the frontal region of the river plume
Diel dynamics and environmental influences on phytoplankton communities in an Andean lagoon: implications for management and conservation
No full textLacustrine environments are unique locations to study temporal fluctuations
derived from natural and artificial sources within a hydrographic basin. The objective of this study was to analyze the diel cycle of physicochemical parameters and their influence on the phytoplankton community structure in open waters, as well as, to evaluate the total phosphorus and nitrogen contents in the vicinity of fish tanks in the lagoon, and to identify the phytoplankton assemblage in the water column in a diel cycle in an open water area during the rainy and dry seasons. Methods: The epilimnion and hypolimnion zones of an open water area were assessed over 24 hours, starting
at 10:00 on day one and finishing at 10:00 on day two, obtaining a total of 36 samples (9 samples at 3-hour intervals, in two lake zones, in two seasons). Sampling employed a Van Dorn sampling bottle, and the Morphologically Based Functional Groups (MBFG), Shannon-Weaver and Simpson Indices were employed to describe the identified genera. Results: Six of the seven parameters monitored registered higher values during the rainy season; only transparency was higher during the dry season. Fifteen genera distributed in nine classes were identified, with richness and diversity being higher in the rainy season. Conclusions: The MBFG and sinking properties of group and genera has influenced the vertical migration of phytoplankton. The daily cycle method effectively captured the fluctuations in physicochemical and phytoplankton parameters over a 24-hour period in both seasons in Chacas Lagoon
Direct Feedback Regulation of E2, T, and hCG in the Brain? Pituitary?Gonad Axis of Japanese Eel (Anguilla japonica) during Artificial Maturation
No full textThe feedback regulatory effects of estrogen (E2) and androgen (T) on the gonadotropinreleasing hormone (GnRH) and gonadotropin (GtH) within the brain?pituitary?gonad (BPG) axis in eels with undeveloped ovaries were investigated through in vivo studies. However, the regulatory role of the BPG axis only became apparent during ovary development in the migratory stage. To further elucidate the direct feedback regulation of the BPG axis, female Anguilla japonica underwent artificial induction of vitellogenesis, and the regulation of BPG axis tissues by GtH (human chorionic gonadotropin, hCG), E2, and T was explored through in vitro exposure. The mRNA expression levels of GnRH (mGnRH), GtH (fshb and lhb), and steroid biosynthesis enzymes (cyp11a1, hsd3b, cyp17a1, and cyp17a2) in the diencephalon, pituitary, and ovary, respectively, were determined. The results showed that the expression level of mGnRH in the diencephalon was significantly downregulated by 0.1 IU/mL hCG but upregulated by both 1 nM E2 and higher concentrations of T, suggesting a direct positive feedback regulation of E2 on mGnRH. In the pituitary, the expression levels of fshb and lhb were upregulated by E2, while fshb was suppressed by T. In the ovaries, the expression of cyp11a1 and hsd3b was upregulated by 1 nM E2, whereas T exposure resulted in an opposite effect. Cyp17a1 mRNA levels did not differ significantly with E2 treatment but were upregulated by 1 nM T. These findings suggest that low concentrations of E2 exhibited positive feedback regulation on all three levels (diencephalon, pituitary, and ovary) of the BPG axis, while T showed weaker and
differential feedback regulation in BPG axis tissues. Overall, this study?s results revealed the direct feedback regulation of hCG, E2, and T on the BPG axis in eels, a phylogenetic base of teleosts
Evidence of 2024 Summer as theWarmest During the Last Four Decades in the Aegean, Ionian, and Cretan Seas
No full textThe summer of 2024 witnessed record-high sea surface temperatures (SST) across the
Aegean, Ionian, and Cretan Seas (AICS), following unprecedented air heatwaves over the sea under a
long-term warming trend of 0.46 ?C/decade for the mean atmospheric temperature (1982?2024). The
respective mean SST trend for the same period is even steeper, increasing by 0.59 ?C/decade. With
mean summer surface waters surpassing 28 ?C, particularly in the Ionian Sea, the southern Cretan,
and northern Aegean basins, this summer marked the warmest ocean conditions over the past four
decades. Despite a relatively lower number of marine heatwaves (MHWs) compared to previous
warm years, the duration and cumulative intensity of these events in 2024 were the highest on record,
reaching nearly twice the levels seen in 2018, which was the warmest until now. Intense MHWs were
recorded, especially in the northern Aegean, with extensive biological consequences to ecosystems
like the Thermaikos Gulf, a recognized MHW hotspot. The strong downward atmospheric heat
fluxes in the summer of 2024, following an interannual increasing four-decade trend, contributed
to the extreme warming of the water masses together with other met-ocean conditions such as
lateral exchanges and vertical processes. The high temperatures were not limited to the surface
but extended to depths of 50 m in some regions, indicating a deep and widespread warming of the
upper ocean. Mechanisms typically mitigating SST rises, such as the Black Sea water (BSW) inflow
and coastal upwelling over the eastern Aegean Sea, were weaker in 2024. Cooler water influx from
the BSW decreased, as indicated by satellite-derived chlorophyll-a concentrations, while upwelled
waters from depths of 40 to 80 m at certain areas showed elevated temperatures, likely limiting their
cooling effects on the surface. Prolonged warming of ocean waters in a semi-enclosed basin such
as the Mediterranean and its marginal sea sub-basins can have substantial physical, biological, and
socioeconomic impacts on the AICS. This research highlights the urgent need for targeted monitoring
and mitigation strategies to address the growing impact of MHWs in the region
Effect of Total Dissolved Gas Supersaturation on Swimming Performance of Migratory Fish for Traversing Velocity Barriers
No full textThis study investigates the impact of total dissolved gas supersaturation (TDGS) on the swimming capabilities of migratory ?sh (S. prenanti), a common issue during high dam discharges in ?ood seasons. We assessed ?sh exposed to 130% TDGS for 2 hr, focusing on their swimming performance in a controlled environment. In our experiments, control group ?sh, utilizing prolonged swimming, showed reduced maximum distances as ?ow velocities increased from 3 to 10 BL/s (body length per second), covering distances between 1,285 and 119 BL. In contrast, TDGS-exposed ?sh achieved only 15%?95% of these distances. Under burst swimming conditions, control group ?sh also demonstrated a decrease in maximum distances with increasing ?ow velocity, achieving 280?124 BL, while TDGS-exposed ?sh reached just 48%?64% of these distances. Notably, the critical ?ow velocity (Ufcrit) for transitioning from prolonged to burst activity level was lower for the TDGS group (7.2 BL/s) compared with the control (9.8 BL/s). In open ?ume trials, TDGS-exposed ?sh displayed a stronger upstream swimming inclination beyond Ufcrit, indicated by quicker times, higher speeds, and shorter trajectories. This study provides novel insights into the adaptive swimming strategies and ?ow velocity responses of ?sh under TDGS stress
PENGGUNAAN TEPUNG LARVA LALAT ASKAR HITAM SEBAGAI SUMBER PROTEIN DALAM TERNAKAN IKAN KERAPU HIBRID (Epinephelus fuscoguttatus ? ? Epinephelus lanceolatus ?)
Get PDF
