Metaperipatus inae sp. nov. (Onychophora: Peripatopsidae) from Chile with a novel ovarian type and dermal insemination

Zootaxa ◽  
2007 ◽  
Vol 1440 (1) ◽  
pp. 21 ◽  
Author(s):  
GEORG MAYER
Keyword(s):  
Reproductive Strategies ◽  
East Asian ◽  
Color Pattern ◽  
Fixed Number ◽  
Evolutionary Development ◽  
The Novel ◽  
Short Term ◽  
Transmission Electron ◽  
Light Fluorescence ◽  
Distinct Separation

Metaperipatus inae sp. nov. (Onychophora: Peripatopsidae) from Chile is described and compared with the previously monotypic M. blainvillei by light, fluorescence, and scanning and transmission electron microscopy. The new species is distinguished from M. blainvillei by having (1) fixed number of legs in both sexes, (2) a characteristic color pattern of the integument, and (3) a larger body size. The structure of the ovaries in both species is different from that in other onychophorans. In contrast to other species of Peripatopsidae and South-East Asian Peripatidae, stalked oocytes are lacking. In addition, the absence of a germinal epithelium surrounding a central lumen contrasts with the organization of ovaries in the Neotropical Peripatidae. A distinct separation into a sterile and a fertile ovarian portion suggests that the novel type might be derived from an ovary with stalked oocytes characteristic of the Peripatopsidae and South-East Asian Peripatidae. The seminal receptacles in both members of Metaperipatus are small and either non-functional or short-term stores since they contained no sperm in the investigated females. The mode of sperm transfer is by dermal insemination, with spermatophores deposited on the female’s body. Based on these observations, the evolutionary development of the ovaries and reproductive strategies in Onychophora are discussed. In addition, an identification key of onychophorans from Chile is provided.

scholarly journals Microscopic study of zinc nanoparticles synthesised using thermosetting polymer

2019 ◽  
Vol 49 (1) ◽  
Author(s):  
Giriraj Tailor ◽  
Jyoti Chaudhay ◽  
Deepshikha Verma ◽  
Bhupendra Kr. Sarma
Keyword(s):  
Electron Microscope ◽  
Xrd Analysis ◽  
The Novel ◽  
X Ray Diffraction ◽  
Zinc Nanoparticles ◽  
Transmission Electron ◽  
Sem Study ◽  
Zinc Salts ◽  
Thermosetting Polymer ◽  
Low Crystalline

AbstractThe present study reports the novel synthesis of Zinc nanoparticles (Zn NPs) by thermal decomposition method and its characterisation by Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), and X-ray Diffraction Measurements (XRD). Synthesis of Zn NPs was achieved by using thermosetting polymer and zinc salts as precursor. Zn NPs were obtained on calcination at 850 °C for 30 min. SEM study reveals that synthesized nanoparticles are spherical in shape. XRD analysis shows that the Zn NPs formed are low crystalline in nature.

Effects of Atovaquone on the Ultrastructural Morphology of Pneumocystis Carinii

1997 ◽  
Vol 3 (S2) ◽  
pp. 81-82
Author(s):  
M.P. Goheen ◽  
M.S. Bartlett ◽  
M.M. Shaw ◽  
S.R. Meshnick ◽  
J.W. Smith
Keyword(s):  
Adverse Reactions ◽  
Pneumocystis Carinii ◽  
Spinner Flask ◽  
Short Term ◽  
Human Embryonic Lung ◽  
Transmission Electron ◽  
Significant Incidence ◽  
Wide Range ◽  
Acquired Immunodeficiency ◽  
Immunodeficiency Syndrome

Pneumocystis carinii pneumonia (PCP) occurs at some time in most patients with acquired immunodeficiency syndrome (AIDS). Trimethoprim/sulfamethoxazole or pentamidine isothionate are the traditional modes of therapy for treatment and prophylaxis of PCP. Unfortunately these drugs are associated with a significant incidence of adverse side effects particularly in patients with AIDS. Toxicity and a growing concern that P. carinii strains are becoming resistant to these compounds is providing the impetus for the search for additional drugs to combat P. carinii. Atovaquone, developed as an antimalarial agent, has activity against a wide range of other organisms, including Toxoplasma sp. and P. carinii, with a lower incidence of adverse reactions during clinical trials. Atovaquone inhibits mitochondrial respiration in P. falciparum and P. carinii. In this study transmission electron microscopy (TEM) was used to observe the effects of atovaquone on P. carinii organisms in short term spinner flask culture.Spinner flask cultures of human embryonic lung cells were inoculated with P. carinii from infected rat lung.

Effects of potassium deficiency and simulated acid rain, alone and in combination, on the ultrastructure of Scots pine needles

1989 ◽  
Vol 19 (11) ◽  
pp. 1402-1411 ◽  
Author(s):  
Toini Holopainen ◽  
Pekka Nygren
Keyword(s):  
Acid Rain ◽  
Scots Pine ◽  
Potassium Deficiency ◽  
Simulated Acid Rain ◽  
Sand Culture ◽  
Short Term ◽  
Transmission Electron ◽  
Resting Period ◽  
Lipid Structures ◽  
Parenchyma Tissue

The effects of potassium deficiency and artificial acid precipitation, alone and in combination, on Scots pine (Pinussilvestris L.) needles were studied using transmission electron microscopy. The seedling material was grown in quartz sand culture and watered with nutrient solution containing 45, 20, 10, or 5 mg of potassium/L; the concentration of other nutrients was constant and equally available for all seedlings. A portion of the seedlings from each group received consecutive acidified water spraying of pH 4.5, 4.0, 3.5, and 3.0, each for 4 days with a 3-day resting period between applications. The potassium deficiency caused an increase in the proportional vacuolar space and severe vesiculation of the tonoplast. Irregularly shaped lipid structures increased in number in the cytoplasm, and lipid bodies also appeared in the vacuoles and occasionally in the chloroplasts. The symptoms related to potassium deficiency were more severe in the transfusion parenchyma cells than in the mesophyll. The lowest level of potassium produced almost complete disorganization of the cellular structures in the transfusion parenchyma tissue, but severe changes were also seen in the mesophyll. The simulated acid rain treatment caused the formation of protrusions in the chloroplasts and an increase in irregularly shaped lipid structures in the cytoplasm throughout the mesophyll tissue, but no clear symptoms were observed inside the bundle sheath. In general, the changes caused by acid rain in the chloroplasts were slight and did not cause serious disorganization of these organelles. When the seedlings were exposed to combination treatment, the typical symptoms of both exposures were observable. The results suggest that the stresses caused by potassium deficiency and short-term foliar acid rain treatment can be distinguished in the needle ultrastructure.

Oxide scale behavior of Al–7.5 mass%Mg alloy containing trace Ca during short-term oxidation

2021 ◽  
Vol 11 (11) ◽  
pp. 1881-1886
Author(s):  
Seong-Ho Ha ◽  
Young-Ok Yoon ◽  
Bong-Hwan Kim ◽  
Hyun-Kyu Lim ◽  
Sung-Hwan Lim ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Oxide Film ◽  
Phase Diagrams ◽  
Film Formation ◽  
Mg Alloy ◽  
Short Term ◽  
Spinel Formation ◽  
Transmission Electron ◽  
Significant Difference

In this study, using transmission electron microscopy and phase diagrams from thermodynamic calculations, we investigated the oxide film formation of Al–7.5 mass%Mg alloy containing Ca traces during short-term oxidation in terms of the thermodynamic stability and multi-element oxides by inter-diffusion based on the results of analysis for the oxide film. For the oxidation test at 515 ˚C, for 1 h, its results showed that there is no significant difference between the Ca-added and Ca-free Al–7.5 mass%Mg alloys was observed, while further exposure caused the Ca-free alloy to gain significant weight. Based on the standard Gibbs free energy for oxide production calculated in this study, CaO was the most preferential product among the single metal oxides examined. As per calculations for MgAl2O4-spinel formation reactions, the spinel formation from MgO was thermodynamically the most favorable. According to the phase diagrams calculated in this study, various multi-element oxides including Ca could possibly form in the oxide layer of Ca-added alloy. The analysis results of transmission electron microscopy confirmed that MgO is the primary oxide in the Al–Mg binary alloys. In oxidation tests conducted for less than 1 h, the spinel was rarely found. The outmost areas of oxide layers correspond to MgO and CaO in Ca-free and Ca-added alloys, respectively. However, in the Ca-added alloy, the inner layer contains certain amounts of Ca, Al, and Mg.

scholarly journals Sex ratio effects on reproductive strategies in humans

2015 ◽  
Vol 2 (1) ◽  
pp. 140402 ◽  
Author(s):  
Ryan Schacht ◽  
Monique Borgerhoff Mulder
Keyword(s):  
Sexual Selection ◽  
Sex Ratio ◽  
Ethnic Group ◽  
Reproductive Strategies ◽  
Situational Factors ◽  
Male Mating ◽  
Mating Effort ◽  
Short Term ◽  
Adult Sex Ratio ◽  
Using Data

Characterizations of coy females and ardent males are rooted in models of sexual selection that are increasingly outdated. Evolutionary feedbacks can strongly influence the sex roles and subsequent patterns of sex differentiated investment in mating effort, with a key component being the adult sex ratio (ASR). Using data from eight Makushi communities of southern Guyana, characterized by varying ASRs contingent on migration, we show that even within a single ethnic group, male mating effort varies in predictable ways with the ASR. At male-biased sex ratios, men's and women's investment in mating effort are indistinguishable; only when men are in the minority are they more inclined towards short-term, low investment relationships than women. Our results support the behavioural ecological tenet that reproductive strategies are predictable and contingent on varying situational factors.

COMMON FEATURES IN EAST ASIAN STOCK MARKETS: LONG-TERM AND SHORT-TERM COMOVEMENTS BETWEEN CHINA AND KOREA

2013 ◽  
Vol 58 (03) ◽  
pp. 1350018
Author(s):  
HAHN SHIK LEE ◽  
SOO IN KIM
Keyword(s):  
Stock Markets ◽  
East Asian ◽  
International Investment ◽  
Cointegration Analysis ◽  
Chinese Stock Market ◽  
Short Term ◽  
Financial Firms ◽  
Contemporaneous Correlation ◽  
East Asian Stock Markets

As increasing attention has been given in recent literature to the potential of the Chinese financial market, we investigate the strength of shared dynamics among East Asian stock markets, by examining both the long-term and short-term comovements. In doing so, the cointegration analysis is used to assess the long-term relationship, whereas the notions of cofeature as well as contemporaneous correlation are employed to discuss the short-term relationship. The basic finding is that evidence for short-term comovement between the Korean and Chinese stock markets appears to be strong, while evidence for long-term relationship is rather weak. Empirical results from subsamples suggest that both the long-term and short-term relationships have strengthened since the acquisition of QFII qualification by Korean financial firms. These observations indicate that the international linkage between the two countries has strengthened along with increasing opportunities for international investment in the Chinese stock market.

scholarly journals Time-conjunctive representations of future events

2019 ◽  
Author(s):  
Stuart Babcock ◽  
Marc Howard ◽  
Joseph McGuire
Keyword(s):  
Response Time ◽  
The Novel ◽  
Correct Item ◽  
Short Term ◽  
Temporal Relationships ◽  
The Future ◽  
Memory Representations ◽  
Future Events ◽  
Probe Letter ◽  
Rule Out

It is widely accepted that people can predict the relative imminence of future events. However, it is unknown whether the timing of future events is represented using only a "strength-like" estimate or if future events are represented conjunctively with their position on a mental timeline. We examined how people judge temporal relationships among anticipated future events using the novel Judgment of Anticipated Co-Occurence (JACO) task. Participants were initially trained on a stream of letters sampled from a probabilistically repeating sequence. During test trials, the stream was interrupted with pairs of probe letters and the participants' task was to choose the probe letter they expected to appear in the stream during a lagged target window 4-6 items (4.3-8.5 seconds) in the future. Participants performed above chance as they gained experience with the task. Because the correct item was sometimes the more imminent probe letter and other times the less imminent probe letter, these results rule out the possibility that participants relied solely on thresholding a strength-like estimate of temporal imminence. Rather, these results suggest that participants held 1) temporally organized predictions of the future letters in the stream, 2) a temporal estimate of the lagged target window, and 3) some means to compare the two and evaluate their temporal alignment. Response time increased with the lag to the more imminent probe letter, suggesting that participants accessed the future sequentially in a manner that mirrors scanning processes previously proposed to operate on memory representations in the short-term judgment of recency task.

Connectedness Among Economic Policy Uncertainties: Evidence from the Time and Frequency Domain Perspectives

2020 ◽  
Vol 8 (5) ◽  
pp. 401-433
Author(s):  
Jinxin Cui ◽  
Huiwen Zou
Keyword(s):  
Economic Policy ◽  
Financial Crisis ◽  
Spillover Effects ◽  
The United States ◽  
Practical Significance ◽  
Policy Uncertainty ◽  
The Novel ◽  
Short Term ◽  
Economic Policy Uncertainty ◽  
Crisis Period

AbstractThis paper investigates the frequency connectedness among economic policy uncertainties of G20 countries using the novel frequency connectedness proposed by Barunik and Krehlik (2018) which can depict the dynamic connectedness not only over time but also across different frequencies. The empirical results obtained in this paper demonstrate that, firstly, the connectedness among economic policy uncertainties is significant, and the spillover effects during the financial crisis and the post-financial crisis period are stronger than the pre-financial crisis period. Secondly, the United States, France, and Australia are the main net-transmitters of the economic policy uncertainty spillovers while Brazil, Italy, Mexico, and Russia act as the main net-recipients of the spillovers. Thirdly, the major international events may significantly enhance the spillover transmissions of economic policy uncertainty among different countries, thus increasing the magnitude of the total connectedness. Finally, the economic policy uncertainty spillovers are mainly transmitted in the short term, i.e., 1∼4 months instead of longer time horizons in terms of the magnitude of the frequency connectedness measures. The findings of this paper not only have profound theoretical and practical significance but also provide several significant implications for the policymakers, supervision agents, international traders, and various investors.

scholarly journals Luminescence Studies and Judd–Ofelt Analysis on SiO2@LaPO4:Eu@SiO2 Submicro-spheres with Different Size of Intermediate Shells

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Xiaowei Zhu ◽  
Kuisuo Yang ◽  
Anping Wu ◽  
He Bai ◽  
Jinrong Bao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Optical Transition ◽  
Dipole Transition ◽  
Rare Earth Ions ◽  
Photoluminescence Intensity ◽  
The Novel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

Abstract The novel submicro-spheres SiO2@LaPO4:Eu@SiO2 with core-shell-shell structures were prepared by connecting the SiO2 submicro-spheres and the rare earth ions through an organosilane HOOCC6H4N(CONH(CH2)3Si(OCH2CH3)3 (MABA-Si). The as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and infrared spectroscopy (IR). It is found that the intermediate shell of the submicro-spheres was composed by LaPO4:Eu nanoparticles with the size of about 4, 5–7, or 15–34 nm. A possible formation mechanism for the SiO2@LaPO4:Eu@SiO2 submicro-spheres has been proposed. The dependence of the photoluminescence intensity on the size of the LaPO4:Eu nanoparticles has been investigated. The intensity ratios of electrical dipole transition 5D0 → 7F2 to magnetic dipole transition 5D0 → 7F1 of Eu3+ ions were increased with decreasing the size of LaPO4:Eu nanoparticles. According to the Judd-Ofelt (J-O) theory, when the size of LaPO4:Eu nanoparticles was about 4, 5–7 and 15–34 nm, the calculated J-O parameter Ω2 (optical transition intensity parameter) was 2.30 × 10−20, 1.80 × 10−20 and 1.20 × 10−20, respectively. The increase of Ω2 indicates that the symmetry of Eu3+ in the LaPO4 lattice was gradually reduced. The photoluminescence intensity of the SiO2@LaPO4:Eu@SiO2 submicro-spheres was unquenched in aqueous solution even after 15 days.

Separate chemical inhibitors of long-term and short-term memory: contrasting effects of cycloheximide, ouabain and ethacrynic acid on various learning tasks in chickens

1977 ◽  
Vol 196 (1123) ◽  
pp. 171-195 ◽  
Keyword(s):  
Visual Discrimination ◽  
Short Term Memory ◽  
Ethacrynic Acid ◽  
Fixed Number ◽  
Long Term Memory ◽  
Training Procedure ◽  
Memory Retention ◽  
Short Term ◽  
Term Memory

Cycloheximide injected into the brains of chickens 10 min before training does not effect their learning of a visual discrimination task, or memory of that task for at least 1 h after training. When tested 24 h later no memory of the training procedure is detectable. In contrast, ouabain injected 10 min before training prevents the expression of learning during training. The block lasts for up to 1 h, but from that time on memory begins to appear. Ouabain does not affect performance when injected just before testing for memory retention 24 h after training. It therefore affects neither the readout of long-term memory nor motivation nor perceptual abilities necessary for performance of the learning task. In birds treated with ouabain, after training on an operant task for heat reward by a procedure requiring a fixed number of reinforcements, memory is absent 20 min later but is well established at 24 h. Cycloheximide blocks long-term memory of this task. Like ouabain, ethacrynic acid, injected into the brain of chickens 10 min before training prevents the expression of learning of visual discrimination. Ethacrynic acid hastens the decline of memory after one-trial passive avoidance learning. It also blocks observational learning. We conclude that ouabain and ethacrynic acid block access to short-term memory, whereas cycloheximide interferes with the registration of long-term memory. Comparing the pharmacology of ethacrynic acid and ouabain their common known actions are on the Na/K fluxes across cell membranes. We suggest that long lasting changes in distribution of these ions in recently active nerve cells may be at the basis of access to memory during and shortly after learning.

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