scholarly journals Age and performance at fledging are a cause and consequence of juvenile mortality between life stages

2018 ◽  
Vol 4 (6) ◽  
pp. eaar1988 ◽  
Author(s):  
Thomas E. Martin ◽  
Bret Tobalske ◽  
Margaret M. Riordan ◽  
Samuel B. Case ◽  
Kenneth P. Dial
Keyword(s):  
Life Stages ◽  
Juvenile Mortality ◽  
And Performance

scholarly journals UNDERSTANDING STRATEGIC ALLIANCE LIFE CYCLE: A 30 YEAR LITERATURE REVIEW OF LEADING MANAGEMENT JOURNALS

2020 ◽  
Vol 21 (2) ◽  
pp. 519-530
Author(s):  
Mayank Dhaundiyal ◽  
Joseph Coughlan
Keyword(s):  
Literature Review ◽  
Strategic Alliances ◽  
Strategic Alliance ◽  
Life Stages ◽  
Alliance Formation ◽  
Research Papers ◽  
Major Life ◽  
Alliance Management ◽  
Holistic Understanding ◽  
And Performance

This paper contributes to the strategic alliance literature by undertaking a literature review of the burgeoning strategic alliance literature published in the last three decades in the mainstream management journals to fulfil two primary objectives. First, to bring a coherent structure into the fairly vast and growing alliance literature and second, to serve as a medium for a holistic understanding of the major life stages of strategic alliances. This is done by first dividing the alliance literature into three distinct yet related alliance life stages namely the pre-alliance stage, alliance formation stage and the alliance management and performance stage, and then by discussing in detail the three alliance stages individually. The paper would be useful for academics as well as practitioners looking to get a holistic understanding of strategic alliances and its three distinct yet related life stages and the key research papers which have been published focussing on each of these alliance stages.

Heraclitean Rivers: Zulu Cultural Transmission

2015 ◽  
Vol 15 (5) ◽  
pp. 493-507 ◽  
Author(s):  
Michal Fux
Keyword(s):  
Observational Learning ◽  
Cultural Transmission ◽  
Cultural Learning ◽  
Action Representation ◽  
Life Stages ◽  
Cognitive Anthropology ◽  
And Performance ◽  
Religious Systems ◽  
Performance Rate ◽  
Gaining Insight

Rituals are part of all religious systems and their transmission and stability have exercised many scholars for decades. Within cognitive anthropology competing views of cultural transmission have emerged in recent years in terms of the mechanisms by means of which cultural forms, including rituals, are transmitted and persist (or not) within societies. Two schools of thought focusing on (1) the “epidemiology of representations” and (2) memetic cultural evolution have informed this study’s goal for gaining insight on the plausibility of cultural learning models as opposed to Sperber et al.’s emphasis on meta-representational processes of representation generation. This study examined 11 life-stages Zulu rituals in terms of participants’ (a) knowledge of them; (b) performance of them; and (c) direct observation of them in order to make some initial judgments about the importance of various forms of direct observational learning for ritual transmission. It was found that while knowledge of rituals was high, observance rate was significantly lower, and performance rate was substantially lower. These results tentatively suggest that an emphasis on understanding those cognitive systems (Hazard Precaution, Action Representation) that might constrain ritual representations (and fit within the Sperberian framework) would be the best way to advance justifiable explanations of ritual transmission.

scholarly journals Population structure and environmental niches of Rimicaris shrimps from the Mid Atlantic Ridge

2021 ◽  
Author(s):  
Pierre Methou ◽  
Ivan Hernandez Avila ◽  
Cecile Cathalot ◽  
Marie-Anne Cambon Bonavita ◽  
Florence Pradillon
Keyword(s):  
Population Structure ◽  
Hydrothermal Vents ◽  
Life Stages ◽  
Population Demographics ◽  
Juvenile Mortality ◽  
Rimicaris Exoculata ◽  
Population Structures ◽  
Mid Atlantic Ridge ◽  
Juvenile Stages ◽  
Potential Factors

Among the endemic and specialized fauna from hydrothermal vents, Rimicaris shrimp surely constitutes one of the most important and emblematic component of these ecosystems. In the Mid Atlantic Ridge, two species affiliated to this genus co-occur: Rimicaris exoculata and Rimicaris chacei that differ by their morphology, their trophic regime as well as by their abundance. The first forms large and dense aggregations on active vent chimney walls in close proximity to vent fluid emissions, whereas the second is recognized as much less conspicuous, living mostly in scattered groups or solitary further away from the fluids. However, the recent revision of Rimicaris juvenile stages from the Mid Atlantic Ridge show that R. chacei abundance would be higher than expected at these early life stages. Here, we describe and compare the population structures of R. exoculata and R. chacei at the Snake Pit and TAG vent fields. We show widely distinct population demographics between the two co-occurring shrimps with a large post settlement collapse in R. chacei population suggesting a large juvenile mortality for this species. We also observe important spatial segregation patterns between the two species and their different life stages. Additionally, our results highlight distinct niches for the earliest juvenile stages of both R. exoculata and R. chacei, compared to all the other life stages. Finally, we discuss the potential factors - predation and competitive interactions among others - that could explain the differences we observe in the population structure of these two species.

scholarly journals Life Stage of Neighbors Determines Neighborhood Effect on Tree Mortality in a Subtropical Forest

2021 ◽  
Author(s):  
Yi He ◽  
Heming Liu ◽  
Qingsong Yang ◽  
Ye Cao ◽  
Mengfang Liang ◽  
...  
Keyword(s):  
Neighborhood Effects ◽  
Tree Mortality ◽  
Life Stage ◽  
Subtropical Forest ◽  
Neighborhood Effect ◽  
Life Stages ◽  
Juvenile Mortality ◽  
Specific Effects ◽  
Single Effect ◽  
Opposing Effects

Abstract Neighborhood effects are a crucial ecological process that allow species to coexist in a forest. Conspecific and heterospecific neighbors, as major classified groups, affect tree mortality through various mechanisms associating with neighbor life stages. However, how neighbor life stages influence neighborhood effects and by what mechanisms remains a knowledge gap. Here we censused the mortality of 82,202 trees representing 30 species in a 20-ha subtropical forest and classified their neighbors into the following life stages: earlier, same and later. Then, we ran generalized linear mixed models to estimate the effect of neighbors at different life stages on tree mortality. Our results showed that conspecific later stage neighbors have effects on increasing tree mortality overall, whereas conspecific earlier stage neighbors have effects on decreasing. Furthermore, these opposing effects could offset each other so that the overall effect of conspecific neighbors on juvenile mortality seems small. In contrast, heterospecific neighbors have effects on decreasing tree mortality overall. These effects are consistent with those of later stage heterospecific neighbors. Our findings demonstrate that neighbors importantly impact tree mortality, and their specific effects are closely related to neighbor life stages. Any single effect from one neighbor life stage could disturb or dominate the total effects of the neighbors. Therefore, the neighbors must be divided into different life stages to best explain the neighborhood effect on forest dynamics.

Marital relations in late adulthood, throughout the retirement process

2001 ◽  
Vol 21 (4) ◽  
pp. 447-469 ◽  
Author(s):  
LIAT KULIK
Keyword(s):  
Power Relations ◽  
Life Stages ◽  
Late Adulthood ◽  
Men And Women ◽  
Marital Relations ◽  
Household Tasks ◽  
Three Stages ◽  
Gender Based ◽  
And Performance

The study investigated marital relations among a sample of 569 Israeli participants at three stages of late adulthood: remote pre-retirement (seven to ten years prior to retirement), near-retirement (up to two years prior to retirement), and post-retirement (up to two years after retirement). The following variables were examined: spousal resources, marital power relations, quality of marriage, and division of household tasks. The study attempted to determine whether there were differences in marital relations during the three life stages, and whether those differences were evident for men and women. The findings reveal that for both men and women, marital relations were more intensive in remote pre-retirement than in the two subsequent stages. In addition, division of feminine household tasks was found to be more egalitarian at later stages of marital life. However, similarities were revealed in most aspects of power relations as well as in spousal resources and performance of masculine household tasks during the three life stages examined. Several gender-based differences were also noted in all three stages. Specifically, the men tended to report an advantage in financial and social resources, as well as in emotional hardiness. With respect to power relations, the men also showed a greater tendency to make major decisions, whereas the women tended to make minor decisions and contributed more toward strengthening the family.

scholarly journals Improving the gnomonic approach with the gnomonicM R-package to estimate natural mortality throughout different life stages

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11229
Author(s):  
Josymar Torrejón-Magallanes ◽  
Enrique Morales-Bojórquez ◽  
Francisco Arreguín-Sánchez
Keyword(s):  
Developmental Stages ◽  
Auxiliary Information ◽  
Stochastic Approach ◽  
R Package ◽  
Biological Information ◽  
Fish Stock ◽  
Natural Mortality ◽  
Life Stages ◽  
And Performance ◽  
Stochastic Functions

Natural mortality (M) is defined as the rate of loss that occurs in a fish stock due to natural (non-fishing) causes and can be influenced by density-dependent or density-independent factors. Different methods have been used to estimate M, one of these is the gnomonic approach. This method estimates M rates by dividing the life cycle of a species into subunits of time that increase as a constant proportion of the time elapsed from birth up to the initiation of each subdivision. In this study, an improved gnomonic approach is proposed to estimate natural mortality throughout different life stages in marine stocks using the gnomonicM package written in R software. This package was built to require data about (i) the number of gnomonic intervals, (ii) egg stage duration, (iii) longevity, and (iv) fecundity. With this information, it is possible to estimate the duration and natural mortality (Mi) of each gnomonic interval. The gnomonicM package uses a deterministic or stochastic approach, the latter of which assesses variability in M by assuming that the mean lifetime fecundity (MLF) is the main source of uncertainty. Additionally, the gnomonicM package allows the incorporation of auxiliary information related to the observed temporal durations of specific gnomonic intervals, which is useful for calibrating estimates of M vectors. The gnomonicM package, tested via deterministic and stochastic functions, was supported by the reproducibility and verification of the results obtained from different reports, thus guaranteeing its functionality, applicability, and performance in estimating M for different ontogenetic developmental stages. Based on the biological information of Pacific chub mackerel (Scomber japonicus), we presented a new case study to provide a comprehensive guide to data collection to obtain results and explain the details of the application of the gnomonicM package and avoid its misuse. This package could provide an alternative approach for estimating M and provide basic input data for ecological models, allowing the option of using estimates of variable natural mortality across different ages, mainly for life stages affected by fishing. The inputs for the gnomonicM packages are composed of numbers, vectors, or characters depending on whether the deterministic or stochastic approach is used, making the package quick, flexible, and easy to use; this allows users to focus on obtaining and interpreting results rather than the calculation process.

Transmission Scanning Electron Microscopy and Energy Analysis with the Siemens ELMISKOP 101

1972 ◽  
Vol 30 ◽  
pp. 450-451
Author(s):  
H. M. Thieringer
Keyword(s):  
Objective Lens ◽  
Transmission Microscopy ◽  
Image Recording ◽  
Mode Of Operation ◽  
Scanning Transmission ◽  
Electron Microscopes ◽  
And Performance ◽  
Convergent Beam ◽  
Ray Path ◽  
Beam Diffraction

It has repeatedly been show that with conventional electron microscopes very fine electron probes can be produced, therefore allowing various micro-techniques such as micro recording, X-ray microanalysis and convergent beam diffraction. In this paper the function and performance of an SIEMENS ELMISKOP 101 used as a scanning transmission microscope (STEM) is described. This mode of operation has some advantages over the conventional transmission microscopy (CTEM) especially for the observation of thick specimen, in spite of somewhat longer image recording times.Fig.1 shows schematically the ray path and the additional electronics of an ELMISKOP 101 working as a STEM. With a point-cathode, and using condensor I and the objective lens as a demagnifying system, an electron probe with a half-width ob about 25 Å and a typical current of 5.10-11 amp at 100 kV can be obtained in the back focal plane of the objective lens.

Angular Resolved Electron Spectroscopy with Parallel Recording

1990 ◽  
Vol 48 (2) ◽  
pp. 370-371
Author(s):  
Huang Min ◽  
P.S. Flora ◽  
C.J. Harland ◽  
J.A. Venables
Keyword(s):  
Electron Spectroscopy ◽  
Low Voltage ◽  
Solid Angle ◽  
Detection System ◽  
Voltage Electron ◽  
Cylindrical Mirror ◽  
Inner Radius ◽  
Channel Plate ◽  
And Performance ◽  
Type Detector

A cylindrical mirror analyser (CMA) has been built with a parallel recording detection system. It is being used for angular resolved electron spectroscopy (ARES) within a SEM. The CMA has been optimised for imaging applications; the inner cylinder contains a magnetically focused and scanned, 30kV, SEM electron-optical column. The CMA has a large inner radius (50.8mm) and a large collection solid angle (Ω > 1sterad). An energy resolution (ΔE/E) of 1-2% has been achieved. The design and performance of the combination SEM/CMA instrument has been described previously and the CMA and detector system has been used for low voltage electron spectroscopy. Here we discuss the use of the CMA for ARES and present some preliminary results.The CMA has been designed for an axis-to-ring focus and uses an annular type detector. This detector consists of a channel-plate/YAG/mirror assembly which is optically coupled to either a photomultiplier for spectroscopy or a TV camera for parallel detection.

Novel epoxy/anhydride alternatives for biological electron microscopy: Physical and performance characteristis of embed 812 and LX 112 in combination with NSA/NMA/DMAE

1989 ◽  
Vol 47 ◽  
pp. 1000-1001
Author(s):  
Joe A. Mascorro ◽  
Gerald S. Kirby
Keyword(s):  
Electron Microscopy ◽  
Flow Rate ◽  
Succinic Anhydride ◽  
Volume Flow Rate ◽  
Mass Density ◽  
Uranyl Acetate ◽  
Volume Flow ◽  
Base Resin ◽  
And Performance ◽  
Acid Anhydrides

Embedding media based upon an epoxy resin of choice and the acid anhydrides dodecenyl succinic anhydride (DDSA), nadic methyl anhydride (NMA), and catalyzed by the tertiary amine 2,4,6-Tri(dimethylaminomethyl) phenol (DMP-30) are widely used in biological electron microscopy. These media possess a viscosity character that can impair tissue infiltration, particularly if original Epon 812 is utilized as the base resin. Other resins that are considerably less viscous than Epon 812 now are available as replacements. Likewise, nonenyl succinic anhydride (NSA) and dimethylaminoethanol (DMAE) are more fluid than their counterparts DDSA and DMP- 30 commonly used in earlier formulations. This work utilizes novel epoxy and anhydride combinations in order to produce embedding media with desirable flow rate and viscosity parameters that, in turn, would allow the medium to optimally infiltrate tissues. Specifically, embeding media based on EmBed 812 or LX 112 with NSA (in place of DDSA) and DMAE (replacing DMP-30), with NMA remaining constant, are formulated and offered as alternatives for routine biological work.Individual epoxy resins (Table I) or complete embedding media (Tables II-III) were tested for flow rate and viscosity. The novel media were further examined for their ability to infilftrate tissues, polymerize, sectioning and staining character, as well as strength and stability to the electron beam and column vacuum. For physical comparisons, a volume (9 ml) of either resin or media was aspirated into a capillary viscocimeter oriented vertically. The material was then allowed to flow out freely under the influence of gravity and the flow time necessary for the volume to exit was recored (Col B,C; Tables). In addition, the volume flow rate (ml flowing/second; Col D, Tables) was measured. Viscosity (n) could then be determined by using the Hagen-Poiseville relation for laminar flow, n = c.p/Q, where c = a geometric constant from an instrument calibration with water, p = mass density, and Q = volume flow rate. Mass weight and density of the materials were determined as well (Col F,G; Tables). Infiltration schedules utilized were short (1/2 hr 1:1, 3 hrs full resin), intermediate (1/2 hr 1:1, 6 hrs full resin) , or long (1/2 hr 1:1, 6 hrs full resin) in total time. Polymerization schedules ranging from 15 hrs (overnight) through 24, 36, or 48 hrs were tested. Sections demonstrating gold interference colors were collected on unsupported 200- 300 mesh grids and stained sequentially with uranyl acetate and lead citrate.

Trace nanoanalysis

1994 ◽  
Vol 52 ◽  
pp. 940-941
Author(s):  
D. E. Newbury ◽  
R. D. Leapman
Keyword(s):  
High Performance ◽  
Secondary Ion Mass Spectrometry ◽  
Detection Efficiency ◽  
Volume Element ◽  
And Performance ◽  
Trace Constituents ◽  
Secondary Ion ◽  
Concentration Levels ◽  
Structure Properties

Trace constituents, which can be very loosely defined as those present at concentration levels below 1 percent, often exert influence on structure, properties, and performance far greater than what might be estimated from their proportion alone. Defining the role of trace constituents in the microstructure, or indeed even determining their location, makes great demands on the available array of microanalytical tools. These demands become increasingly more challenging as the dimensions of the volume element to be probed become smaller. For example, a cubic volume element of silicon with an edge dimension of 1 micrometer contains approximately 5×1010 atoms. High performance secondary ion mass spectrometry (SIMS) can be used to measure trace constituents to levels of hundreds of parts per billion from such a volume element (e. g., detection of at least 100 atoms to give 10% reproducibility with an overall detection efficiency of 1%, considering ionization, transmission, and counting).

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