The pineal gland signals autumn to reindeer (Rangifer tarandus tarandus) exposed to the continuous daylight of the Arctic summer

1994 ◽  
Vol 72 (5) ◽  
pp. 904-909 ◽  
Author(s):  
Karl-Arne Stokkan ◽  
Nicholas J. C. Tyler ◽  
Russel J. Reiter
Keyword(s):  
Plasma Concentration ◽  
Pineal Gland ◽  
Rangifer Tarandus ◽  
Late Onset ◽  
Continuous Light ◽  
Day Length ◽  
The Arctic ◽  
Dark Phase ◽  
Short Period

Plasma melatonin concentrations were measured in blood samples taken hourly for 24–30 h once each month for 1 year in four male semidomesticated reindeer. The animals, which included two long-term castrates, were exposed to natural light and temperature conditions at 69°46′N throughout the study. Melatonin levels were individually variable but did not differ systematically between the castrated and the intact animals. In months characterized by a marked diel light–dark cycle, the plasma concentration of melatonin varied throughout the day; levels were high during the dark phase and low during the light phase. In summer (May, June, and July), when daylight was continuous, and in December, when there was only a short period of twilight in the middle of the day, the pooled hourly mean levels of melatonin did not change significantly across 24 h. However, though the light was continuous, the intensity varied markedly between day and night in summer and all animals showed a slight increase in the plasma concentration of melatonin around midnight in July. In addition, daily secretion of melatonin increased from an annual minimum of 66–84 pg/24 h in June and July to an annual maximum of 525 pg/24 h in August when day length began to decrease from 24 h. We suggest that exposure to continuous light throughout the polar summer reduces the sensitivity of the reindeer pineal gland to light and that, consequently, the drop in light intensity around midnight stimulates secretion of melatonin, which in turn provides photoperiodic information even during periods of continuous daylight. It appears, likewise, that the melatonin profile is enhanced in August, signalling a longer night than that actually experienced. In these two ways, reindeer may receive sufficient photoperiodic information to trigger short-day responses, such as development of the gonads, while still exposed to long days and thus compensate for the late onset of short days in autumn, which is characteristic of high latitudes.

scholarly journals Aerial survey and telemetry data analysis of a peripheral caribou calving area in northwestern Alaska

Rangifer ◽  
2019 ◽  
Vol 39 (1) ◽  
pp. 43-58
Author(s):  
Alexander K. Prichard ◽  
Ryan L. Klimstra ◽  
Brian T. Person ◽  
Lincoln S. Parrett
Keyword(s):  
Industrial Development ◽  
Rangifer Tarandus ◽  
Aerial Survey ◽  
The Arctic ◽  
Primary Data ◽  
Data Sets ◽  
Telemetry Data ◽  
Western Arctic ◽  
Data Source

With industrial development expanding in the Arctic, there is increasing interest in quantifying the impacts of development projects on barren ground caribou (Rangifer tarandus granti). The primary data source to assess caribou distribution and predict impacts in remote areas of Alaska has shifted in recent decades from aerial survey data to telemetry data, but these techniques have different strengths and weaknesses. The ranges of two caribou herds, the Western Arctic Herd and the Teshekpuk Herd, overlap in northwest Alaska between Wainwright and Atqasuk, Alaska. Based on long-term telemetry data sets, this region was thought to be outside of the core calving ranges of both herds. Calving has long been reported to occur in this general area, but early reports assumed caribou were from the Western Arctic Herd and only one systematic aerial survey of caribou density and distribution during calving has been conducted in this area in recent decades. Following interest in industrial development in this area, we conducted aerial strip-transect surveys during early to mid-June 2013–2015 to directly assess the density and distribution of caribou in the area and we used existing telemetry data to compare our results to the seasonal distribution of both herds. Total caribou densities varied between 0.36 and 1.06 caribou/km² among years, and calf densities varied 0.04 and 0.25 calves/km² among years. Contrary to assumptions by early researchers in the area, telemetry data indicated that caribou in this area during early to mid-June were from the Teshekpuk Herd. The use of telemetry data alone underestimated the importance of this area for calving, but the combination of aerial surveys and telemetry data provided complementary information on caribou use of this area showing the importance of collecting the appropriate types of data for assessing potential impacts of development on caribou.

scholarly journals Global warming triggers the loss of a key Arctic refugium

2013 ◽  
Vol 280 (1772) ◽  
pp. 20131887 ◽  
Author(s):  
K. M. Rühland ◽  
A. M. Paterson ◽  
W. Keller ◽  
N. Michelutti ◽  
J. P. Smol
Keyword(s):  
Global Warming ◽  
Sea Ice ◽  
Sediment Cores ◽  
Freshwater Ecosystems ◽  
The Arctic ◽  
Hudson Bay ◽  
Native Communities ◽  
Hudson Bay Lowlands ◽  
Short Period

We document the rapid transformation of one of the Earth's last remaining Arctic refugia, a change that is being driven by global warming. In stark contrast to the amplified warming observed throughout much of the Arctic, the Hudson Bay Lowlands (HBL) of subarctic Canada has maintained cool temperatures, largely due to the counteracting effects of persistent sea ice. However, since the mid-1990s, climate of the HBL has passed a tipping point, the pace and magnitude of which is exceptional even by Arctic standards, exceeding the range of regional long-term variability. Using high-resolution, palaeolimnological records of algal remains in dated lake sediment cores, we report that, within this short period of intense warming, striking biological changes have occurred in the region's freshwater ecosystems. The delayed and intense warming in this remote region provides a natural observatory for testing ecosystem resilience under a rapidly changing climate, in the absence of direct anthropogenic influences. The environmental repercussions of this climate change are of global significance, influencing the huge store of carbon in the region's extensive peatlands, the world's southern-most polar bear population that depends upon Hudson Bay sea ice and permafrost for survival, and native communities who rely on this landscape for sustenance.

Diatoms and aquatic palynomorphs in the sediments of the Eurasian Arctic seas and their significance for paleooceanological investigations in the Arctic

2019 ◽  
pp. 246-251
Author(s):  
Yelena I. Polyakova ◽  
Yekaterina I. Novichkova ◽  
Tatiana S. Klyuvitkina ◽  
Elizaveta A. Agafonova ◽  
Irina M. Kryukova
Keyword(s):  
Bering Sea ◽  
Surface Sediments ◽  
Sea Water ◽  
The Arctic ◽  
Marginal Filter ◽  
Arctic Seas ◽  
Hydrological Parameters ◽  
The Arctic Ocean ◽  
Long Term Studies

Presented the results of long-term studies of diatoms and aquatic palynomorphs in surface sediments of the Arctic seas and the possibility of their use for the reconstructions of paleocirculation water masses, advection of Atlantic and Bering sea water into the Arctic ocean, changes in the river runoff to the seas, sedimentary processes in the marginal filter of the largest rivers, seasonal sea ice cover and other hydrological parameters.

Trends and Prospects of Development of the Oil and Gas Sector in the Context of Digitalization

2020 ◽  
Vol 26 (1) ◽  
pp. 35-45 ◽  
Author(s):  
A. G. Kazanin
Keyword(s):  
Oil And Gas ◽  
Digital Technologies ◽  
Oil And Gas Industry ◽  
Global Market ◽  
The Arctic ◽  
Business And Society ◽  
Gas Industry ◽  
Exploration And Production ◽  
Oil And Gas Sector

The modern oil and gas industry is heavily dependent on the processes and trends driven by the accelerating digitalization of the economy. Thus, the digitalization of the oil and gas sector has become Russia’s top priority, which involves a technological and structural transformation of all production processes and stages.Aim. The presented study aims to identify the major trends and prospects of development of the Russian oil and gas sector in the context of its digitalization and formation of the digital economy.Tasks. The authors analyze the major trends in the development of the oil and gas industry at a global scale and in Russia with allowance for the prospects of accelerated exploration of the Arctic; determine the best practices of implementation of digital technologies by oil and gas companies as well as the prospects and obstacles for the subsequent transfer of digital technologies to the Russian oil and gas industry.Methods. This study uses general scientific methods, such as analysis, synthesis, and scientific generalization.Results. Arctic hydrocarbons will become increasingly important to Russia in the long term, and their exploration and production will require the implementation of innovative technologies. Priority directions for the development of many oil and gas producers will include active application of digital technologies as a whole (different types of robots that could replace people in performing complex procedures), processing and analysis of big data using artificial intelligence to optimize processes, particularly in the field of exploration and production, processing and transportation. Digitalization of the oil and gas sector is a powerful factor in the improvement of the efficiency of the Russian economy. However, Russian companies are notably lagging behind in this field of innovative development and there are problems and high risks that need to be overcome to realize its potential for business and society.Conclusions. Given the strategic importance of the oil and gas industry for Russia, its sustainable development and national security, it is recommendable to focus on the development and implementation of digital technologies. This is crucial for the digitalization of long-term projection and strategic planning, assessment of the role and place of Russia and its largest energy companies in the global market with allowance for a maximum number of different internal and external factors.

scholarly journals Long term results of accelerated 9 mW corneal crosslinking for early progressive keratoconus: the Siena Eye-Cross Study 2

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Cosimo Mazzotta ◽  
Frederik Raiskup ◽  
Farhad Hafezi ◽  
Emilio A Torres-Netto ◽  
Ashraf Armia Balamoun ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Corneal Thickness ◽  
Continuous Light ◽  
Clinical Results ◽  
Asymmetry Index ◽  
Long Term Results ◽  
Distance Visual Acuity ◽  
Long Term Stability ◽  
Uncorrected Distance Visual Acuity

Abstract Purpose To assess clinical results of the 9 mW/5.4 J/cm2 accelerated crosslinking (ACXL) in the treatment of progressive keratoconus (KC) over a span of 5 years. Methods The prospective open non-randomized interventional study (Siena Eye-Cross Study 2) included 156 eyes of 112 patients with early progressive KC undergoing the Epi-Off 9 mW/5.4 J/cm2 ACXL at the Siena Crosslinking Centre, Italy. The mean age was 18.05 ± 5.6 years. The 20-min treatments were performed using the New KXL I (Avedro, Waltham, USA), 10 min of 0.1% HPMC Riboflavin soaking (VibeX Rapid, Avedro, Waltham, USA) and 10 min of continuous-light UV-A irradiation. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), Kmax, coma, minimum corneal thickness (MCT), surface asymmetry index (SAI), endothelial cell count (ECC) were measured, and corneal OCT performed. Results UDVA and CDVA improved significantly at the 3rd (P = 0.028), Δ + 0.17 Snellen lines and 6th postoperative month, respectively (P < 0.001), Δ + 0.23 Snellen lines. Kmax improved at the 6th postoperative month (P = 0.03), Δ − 1.49 diopters from the baseline value. Also, coma aberration value improved significantly (P = 0.004). A mild temporary haze was recorded in 14.77% of patients without affecting visual acuity and without persistent complications. Corneal OCT revealed a mean demarcation line depth at 332.6 ± 33.6 μm. Conclusion The 5-year results of Epi-Off 9 mW/5.4 J/cm2 ACXL demonstrated statistically significant improvements in UCVA and CDVA, corneal curvature and corneal higher-order aberrations which confers a long-term stability for progressive ectasia. Based on the results of the Siena Eye-Cross Study 2, the 9 mW/5.4 J/cm2 ACXL is a candidate to be  the natural evolution of Epi-Off CXL treatment for the management of early progressive corneal ectasia, and thus optimize clinic workflow.

Removal of a compressive mass causes a transient disruption of blood-brain barrier but a long-term recovery of spiny stellate neurons in the rat somatosensory cortex

2021 ◽  
pp. 1-17
Author(s):  
Tzu-Yin Yeh ◽  
Pei-Hsin Liu
Keyword(s):  
Somatosensory Cortex ◽  
Blood Brain Barrier ◽  
Dendritic Spines ◽  
Late Onset ◽  
Brain Barrier ◽  
Blood Brain ◽  
Afferent Fibers ◽  
Prolonged Recovery ◽  
Rat Somatosensory Cortex

Background: In the cranial cavity, a space-occupying mass such as epidural hematoma usually leads to compression of brain. Removal of a large compressive mass under the cranial vault is critical to the patients. Objective: The purpose of this study was to examine whether and to what extent epidural decompression of the rat primary somatosensory cortex affects the underlying microvessels, spiny stellate neurons and their afferent fibers. Methods: Rats received epidural decompression with preceding 1-week compression by implantation of a bead. The thickness of cortex was measured using brain coronal sections. The permeability of blood-brain barrier (BBB) was assessed by Evans Blue and immunoglobulin G extravasation. The dendrites and dendritic spines of the spiny stellate neurons were revealed by Golgi— Cox staining and analyzed. In addition, the thalamocortical afferent (TCA) fibers in the cortex were illustrated using anterograde tracing and examined. Results: The cortex gradually regained its thickness over time and became comparable to the sham group at 3 days after decompression. Although the diameter of cortical microvessels were unaltered, a transient disruption of the BBB was observed at 6 hours and 1 day after decompression. Nevertheless, no brain edema was detected. In contrast, the dendrites and dendritic spines of the spiny stellate neurons and the TCA fibers were markedly restored from 2 weeks to 3 months after decompression. Conclusions: Epidural decompression caused a breakdown of the BBB, which was early-occurring and short-lasting. In contrast, epidural decompression facilitated a late-onset and prolonged recovery of the spiny stellate neurons and their afferent fibers.

scholarly journals Management of a Mycotic Aneurysm in a Patient with COVID-19: A Case Report

Medicina ◽  
2021 ◽  
Vol 57 (6) ◽  
pp. 620
Author(s):  
Muzammil H. Syed ◽  
Mark Wheatcroft ◽  
Danny Marcuzzi ◽  
Hooman Hennessey ◽  
Mohammad Qadura
Keyword(s):  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Stent Graft ◽  
Mycotic Aneurysm ◽  
Neurological Deficits ◽  
Endovascular Stent ◽  
Endovascular Stents ◽  
Abdominal Aortic ◽  
Short Period

The aim of this paper is to share our experience in managing a patient with Klebsiella pneumoniae mycotic abdominal aortic aneurysm who was also infected with COVID-19. A 69-year-old male was transferred to our hospital for the management of an infra-renal mycotic abdominal aortic aneurysm. During his hospital course, the patient contracted severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). He was intubated due to respiratory distress. Over a short period, his mycotic aneurysm increased in size from 2.5 cm to 3.9 cm. An emergency repair of his expanding aneurysm was achieved using our previously described protocol of coating endovascular stents with rifampin. The patient was managed with a rifampin-coated endovascular stent graft without any major complications. Postoperatively, the patient did not demonstrate any neurological deficits nor any vascular compromise. He remained afebrile during his postoperative course and was extubated sometime thereafter. He was then transferred to the ward for additional monitoring prior to his discharge to a rehab hospital while being on long-term antibiotics. During his hospital stay, he was monitored with serial ultrasounds to ensure the absence of abscess formation, aortic aneurysm growth or graft endoleak. At 6 weeks after stent graft placement, he underwent a CT scan, which showed a patent stent graft, with a residual sac size of 2.5 cm without any evidence of abscess or endoleak. Over a follow-up period of 180 days, the patient remained asymptomatic while remaining on long-term antibiotics. Thus, in patients whose surgical risk is prohibitive, endovascular stent grafts can be used as a bridge to definitive surgical management.

scholarly journals Microplastic contamination of the drilling bivalve Hiatella arctica in Arctic rhodolith beds

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sebastian Teichert ◽  
Martin G. J. Löder ◽  
Ines Pyko ◽  
Marlene Mordek ◽  
Christian Schulbert ◽  
...  
Keyword(s):  
Polyethylene Terephthalate ◽  
Water Depth ◽  
The Arctic ◽  
Polymer Composition ◽  
Bivalve Species ◽  
Filter Feeder ◽  
Hiatella Arctica ◽  
Long Term Consequences ◽  
Water Depths

AbstractThere is an increasing number of studies reporting microplastic (MP) contamination in the Arctic environment. We analysed MP abundance in samples from a marine Arctic ecosystem that has not been investigated in this context and that features a high biodiversity: hollow rhodoliths gouged by the bivalve Hiatella arctica. This bivalve is a filter feeder that potentially accumulates MPs and may therefore reflect MP contamination of the rhodolith ecosystem at northern Svalbard. Our analyses revealed that 100% of the examined specimens were contaminated with MP, ranging between one and 184 MP particles per bivalve in samples from two water depths. Polymer composition and abundance differed strongly between both water depths: samples from 40 m water depth showed a generally higher concentration of MPs and were clearly dominated by polystyrene, samples from 27 m water depth were more balanced in composition, mainly consisting of polyethylene, polyethylene terephthalate, and polypropylene. Long-term consequences of MP contamination in the investigated bivalve species and for the rhodolith bed ecosystem are yet unclear. However, the uptake of MPs may potentially impact H. arctica and consequently its functioning as ecosystem engineers in Arctic rhodolith beds.

scholarly journals 1110. Very Late Onset Infections Amongst Long Term Survivors of Kidney Transplantation

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S585-S585
Author(s):  
Harry Cheung ◽  
Marwan M Azar ◽  
Geliang Gan ◽  
Yanhong Deng ◽  
Elizabeth A Cohen ◽  
...  
Keyword(s):  
Cardiovascular Disease ◽  
Clinical Data ◽  
Opportunistic Infections ◽  
Late Onset ◽  
Retrospective Chart Review ◽  
Kidney Transplant Recipients ◽  
Increased Risk ◽  
Simple Logistic ◽  
Long Term Survivors

Abstract Background Kidney transplant recipients (KTR) are at increased risk for infections immediately post-transplant due to intense immunosuppression. However, this risk decreases over time as immunosuppression is tapered. The incidence of infection in KTR many years after transplant is not well characterized. The aim of this study was to describe these “very-late onset infections” (VLIs) ≥ 10 years after KT. Methods We performed a retrospective chart review of patients age ≥ 18 years who underwent KT between 2003 and 2009 and who survived ≥ 10 years post-KT. VLIs included opportunistic infections (OIs) and non-OIs. Demographics, comorbidities, immunosuppression, and clinical data for VLIs ≥ 10 years from KT were collected. Simple logistic regression was performed to determine characteristics associated with risk for VLIs. Results Of 332 KTR that met the inclusion criteria, the majority were male (62.0%), white (59.6%), and the largest proportion was transplanted between the ages of 50-59 (28.3%); 220 (67.9%) were on mycophenolate-based regimens. The mean Charlson Comorbidity Index (CCI) was 4.7 (S.D. 2.0). Of 332, 103 (31.0%) KTR experienced ≥ 1 VLI amounting to 187 episodes. Compared to those without VLI, KTR with VLI were more likely to have diabetes (p=0.005), cardiovascular disease (p=0.004), low ALC (p &lt; 0.001) and require dialysis (p=0.002). Of 103 KTR with VLI, 16 (15.5%) had OIs, while 87 KTR (84.5%) had non-OIs, most commonly urinary tract infection (n=85, 45.5%), pneumonia (n=35, 18.7%) and gastrointestinal infection (n=18, 9.6%). The most commonly isolated pathogens were E. coli (n=30, 16%), K. pneumoniae (n=16, 8.6%), MSSA (n=7, 3.7%), and P. aeruginosa (n=7, 3.7%). Higher CCI, diabetes, dialysis, cerebrovascular, cardiovascular disease and lower ALC were associated with increased risk for VLI (p &lt; 0.05), while living donor KTR was protective (p=0.04). Additionally, every 1 year after transplant was associated with an increased risk of VLI (OR=1.31, p &lt; 0.001). Table 1: Demographics, comorbidities, immunosuppression, and clinical data for all patients Conclusion VLIs were common in long-term survivors of KT and included both conventional and opportunistic pathogens. Every additional year from transplant incurred additional risk for VLI, particularly for those with multiple co-morbidities and lower ALC. Disclosures All Authors: No reported disclosures

scholarly journals An unusually low density ultra-short period super-Earth and three mini-Neptunes around the old star TOI-561

2020 ◽  
Author(s):  
G Lacedelli ◽  
L Malavolta ◽  
L Borsato ◽  
G Piotto ◽  
D Nardiello ◽  
...  
Keyword(s):  
Transit Time ◽  
Time Variation ◽  
Planetary System ◽  
Radial Velocities ◽  
Low Density ◽  
Outer Planets ◽  
Short Period ◽  
The Stability

Abstract Based on HARPS-N radial velocities (RVs) and TESS photometry, we present a full characterisation of the planetary system orbiting the late G dwarf After the identification of three transiting candidates by TESS, we discovered two additional external planets from RV analysis. RVs cannot confirm the outer TESS transiting candidate, which would also make the system dynamically unstable. We demonstrate that the two transits initially associated with this candidate are instead due to single transits of the two planets discovered using RVs. The four planets orbiting TOI-561 include an ultra-short period (USP) super-Earth (TOI-561 b) with period Pb = 0.45 d, mass Mb = 1.59 ± 0.36 M⊕ and radius Rb = 1.42 ± 0.07 R⊕, and three mini-Neptunes: TOI-561 c, with Pc = 10.78 d, Mc = 5.40 ± 0.98 M⊕, Rc = 2.88 ± 0.09 R⊕; TOI-561 d, with Pd = 25.6 d, Md = 11.9 ± 1.3 M⊕, Rd = 2.53 ± 0.13 R⊕; and TOI-561 e, with Pe = 77.2 d, Me = 16.0 ± 2.3 M⊕, Re = 2.67 ± 0.11 R⊕. Having a density of 3.0 ± 0.8 g cm−3, TOI-561 b is the lowest density USP planet known to date. Our N-body simulations confirm the stability of the system and predict a strong, anti-correlated, long-term transit time variation signal between planets d and e. The unusual density of the inner super-Earth and the dynamical interactions between the outer planets make TOI-561 an interesting follow-up target.

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