Reproductive-cycle plasticity in yellow-cedar (Chamaecyparisnootkatensis)

1991 ◽  
Vol 21 (9) ◽  
pp. 1360-1364 ◽  
Author(s):  
Y. A. El-Kassaby ◽  
J. Maze ◽  
D. A. MacLeod ◽  
S. Banerjee
Keyword(s):  
Reproductive Cycle ◽  
Vancouver Island ◽  
Significant Delay ◽  
Continue Development ◽  
Cold Temperatures ◽  
Size And Shape ◽  
Seed Extraction ◽  
Fresh Pollen ◽  
The Impact

In 1987, a study was initiated to determine the properties of seed from apparently premature cones of yellow-cedar (Chamaecyparisnootkatensis (D. Don) Spach) on southwestern Vancouver Island. After pollination with fresh pollen in February, all cones showed signs of maturation (i.e., drying and shedding) by December. Samples of these 1-year-old cones were collected for seed extraction and germination tests. Germination ranged between 10 and 42% for isolated cones (i.e., bagged) and between 0 and 25% for unisolated cones. Similar germination results were obtained for the 1988 and 1989 cone crops. Anatomical observations revealed that the 10-month-old embryos were similar in both size and shape to embryos from 2-year-old seeds. It was concluded that transplanting yellow-cedar trees to warmer, low-elevation sites enabled seed cones to continue development without significant delay caused by dormancy induced by cold temperatures at higher elevations. This alteration of normal phenology reflects the impact of environmental contingencies on development.

scholarly journals Effect of extreme cold temperatures on quasi-static indentation and impact behavior of woven carbon fiber epoxy composite sandwich panels with nomex honeycomb core

2021 ◽  
pp. 109963622199387
Author(s):  
Mathilde Jean-St-Laurent ◽  
Marie-Laure Dano ◽  
Marie-Josée Potvin
Keyword(s):  
Epoxy Composite ◽  
Impact Behavior ◽  
Effect Of Temperature ◽  
Cold Temperatures ◽  
Composite Sandwich Panels ◽  
Composite Sandwich ◽  
Static Indentation ◽  
Nomex Honeycomb ◽  
Extreme Cold ◽  
The Impact

The effect of extreme cold temperatures on the quasi-static indentation and the low velocity impact behavior of woven carbon/epoxy composite sandwich panels with Nomex honeycomb core was investigated. Impact tests were performed at room temperature, –70°C, and –150°C. Two sizes of hemispherical impactor were used combined to three different impactor masses. All the impact tests were performed at the same initial impact velocity. The effect of temperature on the impact behavior is investigated by studying the load history, load-displacement curves and transmitted energy as a function of time curves. Impact damage induced at various temperatures was studied using different non-destructive and destructive techniques. Globally, more damages are induced with impact temperature decreasing. The results also show that the effect of temperature on the impact behavior is function of the impactor size.

Soil seed bank and vegetation dynamics in Sahelian fallows; the impact of past cropping and current grazing treatments

2004 ◽  
Vol 20 (6) ◽  
pp. 683-691 ◽  
Author(s):  
Bruno Hérault ◽  
Pierre Hiernaux
Keyword(s):  
Seed Bank ◽  
Management Practices ◽  
Soil Seed Bank ◽  
Residual Effects ◽  
Ex Situ ◽  
Phosphorus Fertilizer ◽  
Wet Season ◽  
Seed Extraction ◽  
The Impact

The soil seed bank in a 5-y-old Sahelian fallow was studied through seed extraction and compared with germinations recorded either in controlled conditions, ex situ in a glasshouse, or in the field. The influence of phosphorus fertilizer and mulch application during the preceding crop period, and that of seasonal grazing regimes applied the last 2 y of fallowing, were assessed on the composition of the seed stock. Ctenium elegans, Fimbristylis hispidula, Merremia pinnata and Phyllanthus pentandrus accounted together for 75% of extracted seeds, 72% of ex situ, and 62% of in situ seedlings. Mulch treatment was correlated with the first axis of the canonical correspondence analyses performed on the seedling datasets. Mulch and phosphorus fertilizer treatments held similar responses, as they both favoured the seed bank of erect dicotyledons such as P. pentandrus and Cassia mimosoides. On the whole, the effects of grazing remained modest compared with the residual effects of past crop management practices. However, seedling densities increased as a result of dry-season grazing, while the soil seed bank decreased with wet-season grazing. Grazing also reduced the spatial heterogeneity of the seed bank rather than the overall number of species.

Abstract P153: SARS-CoV-2 (COVID-19) Protection Efforts on Acute Stroke Treatment

Stroke ◽  
2021 ◽  
Vol 52 (Suppl_1) ◽  
Author(s):  
Jessica Greenwood ◽  
Starlie Belnap ◽  
Rodney Bedgio ◽  
Guilherme Dabus ◽  
Italo Linfante ◽  
...  
Keyword(s):  
Stroke Volume ◽  
Endovascular Treatment ◽  
Acute Stroke ◽  
Symptom Onset ◽  
Onset Time ◽  
Fold Increase ◽  
Medical Attention ◽  
Hospital Treatment ◽  
Significant Delay ◽  
The Impact

Introduction: It is unclear how the interventions designed to restrict community and in-hospital exposure to the SARS-CoV-2 virus affected the care for stroke patients seeking acute treatment. The objective of the following study was to determine the impact COVID-19 has had on the treatment times for patients evaluated as acute stroke alerts at Baptist Hospital of Miami (BHM). A co-primary objective of the study was to assess the risk of contracting SARS-CoV-2 within 2 weeks from hospital discharge. Methods: This retrospective, two phase study was conducted between December 2019 and April 2020. In phase one, we assessed time from symptom onset to hospital arrival, number of strokes with witnessed onset, and in-hospital treatment times pre & post implementation of Covid-19 preventive exposure measures. In phase two of the study, a telephone survey was conducted on the post implementation group to assess the risk of patients developing symptoms or testing positive for SARS-CoV-2 from hospital admission up to two weeks post discharge. Results: Phase I demonstrated there was a 40% decline in stroke volume, but no significant delay to seek medical attention post implementation of the SARS prevention strategies. On average individuals in the pre-group (n=155) waited approximately 260 minutes (SE=24) to seek medical attention vs. 203 minutes (SE=27) minutes for the post-group (n=87). However, there was nearly a six-fold increase in the percentage of cases with unknown symptom onset post implementation of COVID-19 safety precautions. There was significant delay in administering IV alteplase, increasing from 24 mins (n=16) to 33 mins (n=21) post implementation; delays observed for endovascular treatment were not significant (pre, n=13 mean= 73 mins, post n=12 mean= 82 mins). The volume of patients treated with either IV alteplase and/or endovascular treatment remained similar. Phase II of the study is on-going, results will be available for the ISC. Discussion: The COVID-19 crisis in our community was associated with a six-fold increase in the percentage of cases with unknown stroke onset time. Besides a marked decrease in stroke volume, we did not evidence significant delays to either seek or provide acute stroke care outside a modest increase in door to needle time.

MICROSTRUCTURAL CHANGES OF ALUMINIUM ALLOY A319 ON COOLING SLOPE PLATE

2016 ◽  
Vol 78 (6-9) ◽  
Author(s):  
Ahmad Muhammad Aziz ◽  
Mohd Zaidi Omar ◽  
Zainuddin Sajuri ◽  
Mohd Shukor Salleh
Keyword(s):  
Grain Size ◽  
Shape Factor ◽  
Casting Process ◽  
Impact Zone ◽  
Dendritic Microstructure ◽  
Size And Shape ◽  
Cooling Slope ◽  
Grain Size And Shape ◽  
Bottom Zone ◽  
The Impact

The cooling slope (CS) casting process is one of the simplest methods for producing a non-dendritic microstructure. To more clearly determine how this microstructure is formed, specifically in A319, requires an examination of how the dendritic microstructure evolves along the entirety of the CS plate. Yet until now, there are still unclear on the verification of microstructures changes on the CS plate. Based on experimental results, this paper offers an explanation for the mechanism involved in producing a nearly globular microstructure in A319. In addition, the mechanism is verified by using the planimetry method. Moreover a quantitative method is used to determine the grain size and shape factor to provide further support for the proposed mechanism. The solid fraction of α-Al at the impact zone is 70 % which is the highest compared to other zones. Grain size and shape factor shown a decreasing and increasing value respectively from the impact zone until the bottom zone.

Effect of cold temperature on the rate of natural attenuation of benzene, toluene, ethylbenzene, and the three isomers of xylene (BTEX)

2010 ◽  
Vol 47 (5) ◽  
pp. 516-527 ◽  
Author(s):  
Ania C. Ulrich ◽  
Kristen Tappenden ◽  
James Armstrong ◽  
Kevin W. Biggar
Keyword(s):  
Natural Attenuation ◽  
Field Conditions ◽  
Published Data ◽  
Anaerobic Conditions ◽  
Data Set ◽  
Cold Temperatures ◽  
Site Analysis ◽  
Benzene Toluene ◽  
The Impact ◽  
Hydrogeological Information

The impact of cold temperatures on natural attenuation rates is poorly understood and compounded by the lack of published data, particularly under field conditions. This paper presents a collection of data from monitoring and remediation projects completed at cold temperatures. The data set was compiled from 55 studies under anaerobic conditions (46 field and nine laboratory) from sites where groundwater temperatures are typically less than 15 °C. By normalizing the data to +5 and +10 °C, the scatter in rates for BTEX degradation in groundwater was reduced by 33% to 66%. In an attempt to address the paucity of data on natural attenuation rates under cold temperatures, this study has compiled and normalized 101 anaerobic BTEX natural attenuation rates. Eleven of the 55 studies and 43 of the 101 rates presented in this study have not been previously published. Additionally, this study has compiled, for each site, relevant contaminant and hydrogeological information that can be reviewed to choose appropriate rates for preliminary site analysis.

scholarly journals Short- and long-term effects of diving on pulmonary function

2017 ◽  
Vol 26 (143) ◽  
pp. 160097 ◽  
Author(s):  
Kay Tetzlaff ◽  
Paul S. Thomas
Keyword(s):  
Lung Function ◽  
Pulmonary Function ◽  
Ambient Pressure ◽  
Small Airways ◽  
Long Term Effects ◽  
Cold Temperatures ◽  
Factors Associated ◽  
Stress Changes ◽  
The Impact

The diving environment provides a challenge to the lung, including exposure to high ambient pressure, altered gas characteristics and cardiovascular effects on the pulmonary circulation. Several factors associated with diving affect pulmonary function acutely and can potentially cause prolonged effects that may accumulate gradually with repeated diving exposure. Evidence from experimental deep dives and longitudinal studies suggests long-term adverse effects of diving on the lungs in commercial deep divers, such as the development of small airways disease and accelerated loss of lung function. In addition, there is an accumulating body of evidence that diving with self-contained underwater breathing apparatus (scuba) may not be associated with deleterious effects on pulmonary function. Although changes in pulmonary function after single scuba dives have been found to be associated with immersion, ambient cold temperatures and decompression stress, changes in lung function were small and suggest a low likelihood of clinical significance. Recent evidence points to no accelerated loss of lung function in military or recreational scuba divers over time. Thus, the impact of diving on pulmonary function largely depends on factors associated with the individual diving exposure. However, in susceptible subjects clinically relevant worsening of lung function may occur even after single shallow-water scuba dives.

scholarly journals Reducing the Impact of Forest Harvesting on the Vancouver Island Tourism Industry

2016 ◽  
Vol 92 (01) ◽  
pp. 101-111 ◽  
Author(s):  
Kyle W. Hilsendager ◽  
Howard W. Harshaw ◽  
Robert A. Kozak
Keyword(s):  
British Columbia ◽  
Vancouver Island ◽  
Forest Harvesting ◽  
Tourism Industry ◽  
Structured Interviews ◽  
Tourism Resource ◽  
Negative Impacts ◽  
Visual Impacts ◽  
The Impact ◽  
Industry Professionals

British Columbia forests have traditionally been managed for timber production. However, the increasing importance of nature-based tourism within the province means that forests also have significant value as a tourism resource. This can lead to conflicts between the forestry and tourism industries. This article examines tourism and forestry interests on Vancouver Island and discusses ways that forests could be managed to reduce negative impacts to the tourism industry. Eighteen semi-structured interviews were conducted with forestry and tourism industry professionals on Vancouver Island and elsewhere in British Columbia. Findings suggest that visual impacts associated with forestry can negatively impact tourism. It also appears that forestry receives a much higher priority than tourism when it comes to forest management, despite the vital importance of the tourism industry to the Vancouver Island economy. Displeasure over the lack of communication requirements between the forest industry and other stakeholders was also documented. The implementation of formal agreements between the two industries may potentially reduce conflicts between these two industries on Vancouver Island. Identification and special management of highly valuable tourism areas may also provide benefits to the Vancouver Island tourism industry.

Toward a Molecular Understanding of the Impact of Crystal Size and Shape on Punch Sticking

2020 ◽  
Vol 17 (4) ◽  
pp. 1148-1158 ◽  
Author(s):  
Shubhajit Paul ◽  
Lisa J. Taylor ◽  
Brendan Murphy ◽  
Joseph F. Krzyzaniak ◽  
Neil Dawson ◽  
...  
Keyword(s):  
Crystal Size ◽  
Size And Shape ◽  
The Impact
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