Geminal Research Articles

Phonetic analysis of Korean elementary students who had overseas study at early ages

Purpose: The number of the repatriated Korean students who had overseas study at early ages is increasing. They received foreign education, they can speak international languages, but they have many difficulties in articulation and intonation of the Korean language. This study aims to measure closure and aspiration duration, length of consonants, length of sub- sequent vowels, and ratio of consonants against subsequent vowels in vowel consonant vowel (VCV) syllables. - - Methods: This study compares the acoustic and phonetic characteristics of repatriated and native students, the ratio of articulation error of Korean plosives, the closure and aspiration duration, and the ratio of the aspiration duration against the closure duration. Results :The ratio of articulation error of Korean plosives between repatriated and native students is 19% and 2%, respec- tively. The closure duration was significantly longer in repatriated students than in native students. The aspiration duration was significantly longer in repatriated students than in native students. No difference was found in the ratio of aspiration duration against closure duration between the native and repatriated students. Conclusion :This study can be a good reference for estimating the phonetic difficulties of Korean elementary students who had overseas study at early ages. (Korean J Pediatr 2010;53:579-584)

Magnetic field effect in homogeneous medium for triplet born radical ions : a way for assessment of inter-radical distance in intermolecular photoinduced electron transfer

Photoinduced electron transfer (PET) reaction involves excitation of either donor or acceptor prior to electron transfer. The PET reaction might occur in the singlet or in the triplet electronic state of the chromophore. These reactions could be influenced by the presence of internal or external magnetic field since radical ions with free electrons are generated as intermediates. Magnetic field effect (MFE) in homogeneous medium could be observed on exciplex luminescence, however the change is very small as the rate of recombination is very high owing to the singlet spin correlation of the geminate radical ion pair (RIP). On the other hand for the triplet born RIPs the detection of MFE needs confinement of the triplet species because at ambient temperature the lifetime of the solvent cages containing spin correlated RIP in homogeneous solvent is 10 -10 s whereas the rate of intersystem crossing is 10 -8 s. It is possible to confine the triplet born radicals by using organized assemblies like micelles, reverse micelles, etc., highly viscous solvents at low temperature or long chain biradicals which help to reduce fast escape and thus retain the spin-correlation between the partners of the geminate RIP. MFE is a composite of diffusion dynamics, spin dynamics leading to intersystem crossing and recombination of free ion formation. The effect is optimized only when the inter-radical distance through diffusion becomes sufficient to make exchange interaction between free electrons negligible retaining the original spin-correlation in the solvent cage. In this review we would like to highlight a few systems where MFE for the triplet born radicals could be observed even in homogeneous media due to some specific interactions other than covalent linking, which also helps to assess the inter-radical distance in such intermolecular PET, which is very rare.

영어 모음사이 자음의 인지와 발화에서 철자의 영향: 파일럿 연구

한국어에서는 모음사이에서 겹자음이 나타날 수 있으나 영어에서는 이것이 불가능하므로 영어를 배우는 한국 학생들이 <TEX>$su\underline{mm}er$</TEX>와 같이 겹자음 철자를 포함하는 단어들을 발음할 때 철자의 겹자음을 모두 발음하는 오류를 흔히 범한다. 따라서 본 파일럿 연구에서는 한국 학생들이 영어 겹자음 철자를 어떻게 발음하고 인지하는지 살펴보기 위해서 영어 겹자음과 단자음의 (유사) 최소변별쌍으로 구성된 36개의 실제어를 20명의 대학생이 듣고 발음하는 인지와 발화 실험을 실행하였다. 실험 결과 한국 학생들은 철자의 영향으로 영어 단자음 철자 단어를 발음할 때보다 겹자음 철자 단어를 발음할 때 이중으로 길게 발음하는 오류를 더 흔히 범해서 겹자음 철자 단어의 정확율보다 단자음의 정확율이 크게 높았으며, 인지의 경우에도 마찬가지로 단자음 철자 단어의 인지 정확율이 겹자음 철자보다 확연하게 높았다. 덧붙여, 한국 학생들의 영어 유성 파열음의 발화 오류율이 낮은 이유를 한국어 음운 체계의 전이로 설명하였다. 끝으로, 한국학생들의 발화를 스펙트로그램을 통해서 분석함으로써 영어 단자음 철자보다는 겹자음 철자에서 더 많은 발화오류를 일으키는 것도 보여주었고 또한 교육적인 함축점도 제안하였다. While Korean allows the same consonants at the coda of the preceding syllable and at the onset of the following syllable, English does not allow the geminate consonants in the same intervocalic position. Due to this difference between Korean and English, Korean learners of English tend to incorrectly produce geminate consonants for English geminate graphemes as in <TEX>$su\underline{mm}er$</TEX>. Based on this observation, a pilot study was designed to investigate how Korean learners of English perceive and produce English doubleton graphemes and singleton graphemes. Twenty Korean college students were asked to perform a forced-choice perception test as well as a production test for the 36 real word stimuli which consist of (near) minimal pairs of singleton and doubleton graphemes. The result showed that the accuracy rates for the words with singleton graphemes were higher than those for the words with doubleton graphemes both in perception and production because the subjects misperceived and misproduced the doubleton graphemes as geminates due to orthographic influence. In addition, the low error rates of the word with voiced stops were accounted for by Korean language transfer. Further, spectrographic analyses were provided where more production errors were witnessed in doubleton grapheme words than singleton grapheme words. Finally, pedagogical implications are provided.

Electronic Structure and Geminate Pair Energetics at Organic–Organic Interfaces: The Case of Pentacene/C60 Heterojunctions

AbstractOrganic semiconductors are characterized by localized states whose energies are predominantly determined by electrostatic interactions with their immediate molecular environment. As a result, the details of the energy landscape at heterojunctions between different organic semiconductors cannot simply be deduced from those of the individual semiconductors, and they have so far remained largely unexplored. Here, microelectrostatic computations are performed to clarify the nature of the electronic structure and geminate pair energetics at the pentacene/C60 interface, as archetype for an interface between a donor molecule and a fullerene electron acceptor. The size and orientation of the molecular quadrupole moments, determined by material choice, crystal orientation, and thermodynamic growth parameters of the semiconductors, dominate the interface energetics. Not only do quadrupoles produce direct electrostatic interactions with charge carriers, but, in addition, the discontinuity of the quadrupole field at the interface induces permanent interface dipoles. That discontinuity is particularly striking for an interface with C60 molecules, which by virtue of their symmetry possess no quadrupole. Consequently, at a pentacene/C60 interface, both the vacuum‐level shift and geminate pair dissociation critically depend on the orientation of the pentacene π‐system relative to the adjacent C60.

Engineering the electronic structure of the CuPc/BPE‐PTCDI interface by WO3 doping of CuPc

AbstractWe investigate the electronic interface properties of an organic bilayer heterojunction solar cell, built of CuPc/BPE‐PTCDI as donor/acceptor system. Band alignment of this interface and interface potentials were measured using synchrotron induced photoemission spectroscopy (SXPS) on stepwise deposited BPE‐PTCDI on doped and non doped CuPc. Using non doped CuPc at thermodynamic equilibrium the bands bend at the interface in a direction that hinders dissociation of geminate pairs.As a measure to form a band bending that supports geminate pair separation p‐doping of CuPc is tested. As dopant WO3 was applied being a promising material for p‐doping of CuPc due to its high ionization potential. At the doped CuPc/BPE‐PTCDI interface the internal field is actually reversed now driving holes in CuPc and electrons in BPE‐PTCDI away from the interface.

Imaging Hindered Rotations of Alkoxy Species on TiO2(110)

We present the first scanning tunneling microscopy (STM) study of the rotational dynamics of organic species on any oxide surface. Specifically, variable-temperature STM and dispersion-corrected density functional theory (DFT-D) are used to study the alkyl chain conformational disorder and dynamics of 1-, 2-, 3- and 4-octoxy on rutile TiO(2)(110). Initially, the geminate pairs of the octoxy and bridging hydroxyl species are created via octanol dissociation on bridging-oxygen (O(b)) vacancy defects. The STM images provide time-averaged snapshots of octoxy species rotating among multiple energetically nearly degenerate configurations accessible at a given temperature. In the calculations we find that the underlying corrugated potential energy surface is a result of the interplay between attractive van der Waals dispersion forces, leading to weak attractive C...Ti and repulsive C...O(b) interactions which lead to large barriers of 50-70 kJ mol(-1) for the rotation of the octoxy alkyl chains across the O(b) rows. In the presence of the geminate hydroxyl groups we find that the relative populations of the various conformations as well as the rotational barriers are perturbed by the presence of geminate hydroxyl due to additional C...hydroxyl repulsions.

Long-range exciton dissociation in layered organic solar cells

Long-range charge transfer in a donor-spacer-acceptor system is observed. When tris-8-hydroxy-quinolinato aluminum (Alq3) is used as a spacer between copper phthalocyanine (CuPc, donor) and C60 (acceptor), electron transfer over 14 nm from CuPc to C60 and hole transfer over 30 nm from C60 to CuPc occur. Two charge transfer mechanisms are identified by this study: electron tunneling via gap states of Alq3 (the lowest unoccupied molecular orbitals of Alq3 act as an energy barrier) and hole transport via the highest occupied molecular orbitals of Alq3, which act as step-stone levels. A thin spacer with suitable energy levels is suggested to improve the power conversion efficiency by inhibiting the recombination of geminate pair polarons.

Correlation of Heterojunction Luminescence Quenching and Photocurrent in Polymer‐Blend Photovoltaic Diodes

Charge generation in organic solar cells proceeds via photogeneration of excitons in the bulk that form geminate electron–hole pairs at the heterojunction formed between electron donor and acceptors. It is shown that an externally applied electric field increases the number of free charges formed from the geminate pair, and quenches the luminescence from the relaxed exciplex with one-to-one correspondence.

The effect of word segmental structure on consonant length categorization by Finnish speakers.

While both Finnish and Japanese have a contrast in segmental length, previous research [Aoyama (2000)] has found that Finnish listeners exhibit a sharper identification for consonant length contrasts. The present study examines the effect of segmental structure on length categorization in the two languages. Twenty-two Finnish speakers were presented acoustic stimuli, where silence intervals with the duration of seven equal steps were embedded in three pairs of nonsense words spoken by a Finnish and a Japanese speaker and gave forced choice responses between single and geminate. The result shows that the slope of the identification function is steeper for the stimuli produced by the Finnish talker. Moreover, the study finds earlier identification with geminate for the words with CVC initial syllable as compared to CV. This effect of segmental structure, however, is restricted when the target consonant is located in the third syllable and for the stimuli produced by the Finnish speaker. These observations suggest that the listeners refer to their knowledge that the vowel in the second syllable is longer when preceded by CV syllable, the phonetic fact known as “half-long vowel” in Finnish [Suomi et al. (2003)]. [Work supported by Finlandia Foundation National Scholarship.]

Out of sight, out of mind: high cryptic diversity obscures the identities and histories of geminate species in the marine bivalve subgenus Acar

AbstractAim The rise of the Isthmus of Panama and the formation of ‘geminate’ species pairs serves as an important model of allopatric speciation. However, to function as a model system, hypothesized geminates must first be shown to be each other’s closest living relatives. If the presence of cryptic taxa obscures true relationships, the biogeographical histories of transisthmian taxa are likely to be misinterpreted. We have therefore completed a phylogeographic survey of the transisthmian bivalve subgenus Acar in the genus Barbatia to characterize patterns of tropical American diversity and to place transisthmian taxa in a regional phylogeographic context.Location Tropical America.Methods Mitochondrial cytochrome c oxidase I (COI) and nuclear internal transcribed spacer (ITS) sequences were obtained from 233 specimens of Acar. Sequences were analysed using cladistic and Bayesian methods. Divergence times between species were inferred from net nucleotide divergences and a coalescence‐based method.Results The survey revealed 22 COI clades that were also monophyletic at ITS, indicating that the taxonomy of Acar is potentially greater than a fivefold diversity underestimate. The lone previously recognized geminate [Barbatia (Acar) gradata and Barbatia (Acar) domingensis] is composed of 15 clades. Among the four transisthmian lineages identified, two diverged more than 14 Ma; the two other geminates split just prior to the time of final seaway closure. In addition to a fourfold increase in the number of known geminates, our data show that within‐basin diversification has been more impressive, with one geminate splitting into five monophyletic clades in the Western Atlantic alone since seaway closure. Electron microscopy of the larval shells of specimens indicates that the transisthmian lineage with the greatest rate of post‐Isthmian diversification possesses non‐planktonic larvae, a life‐history feature linked to high speciation rates.Main conclusions Our analyses revealed that the identities of geminate pairs split by the Isthmus of Panama were obscured by extremely high tropical American cryptic diversity. Although we have identified four geminates, only two appear to have been split by the Isthmus. Our uncovering of extensive post‐Isthmian diversification is consistent with the palaeontological perspective that the final closure of the Central American Seaway was followed by high rates of subgeneric diversification, particularly in the tropical Western Atlantic.

The hopping kinetics of geminate recombination in organic crystals

The time dependences of the survival probability, recombination rate, and polarization current of geminate pairs were obtained by the Monte Carlo method for various lattice parameter values. Quantitative criteria of the applicability of the diffusion-drift approximation were found.

Revision of the amphiamerican Neotetraonchus Bravo-Hollis, 1968 (Monogenoidea: Dactylogyridae), with a description of N. vegrandis n. sp. from the gill lamellae of the blue sea catfish Ariopsis guatemalensis (Siluriformes: Ariidae) off the Pacific Coast of Mexico

Neotetraonchus Bravo-Hollis, 1968 is revised and reassigned to the Dactylogyridae Bychowsky, 1933 based on examinations of specimens representing four species from the gill lamellae of sea catfishes (Ariidae). The monotypic Neotetraonchidae Bravo-Hollis, 1968 is placed in synonymy with the Dactylogyridae. Neotetraonchus bychowskyi Bravo-Hollis, 1968 (type-species), is redescribed from the tete sea catfish Ariopsis seemanni (Günther) (type-host) in the eastern Pacific Ocean off Panama (new geographical record). Neotetraonchus vegrandis n. sp. is described from the blue sea catfish A. guatemalensis (Günther) off the Pacific Coast of Mexico. Neotetraonchus bravohollisae Paperna, 1977 is redescribed from the hardhead sea catfish A. felis (L.) in the Gulf of Mexico off the Yucatan Peninsula. Neotetraonchus felis (Hargis, 1955) Paperna, 1977 is redescribed from A. felis in the Gulf of Mexico off Mississippi and the Yucatan Peninsula (new geographical record). Morphological similarities between species of Neotetraonchus suggest the likely presence of geminate species pairs flanking the Isthmus of Panama.

Influence of light and gibberellin on the germination velocity of coffee seeds (Coffea arabica L.)

There are various factors that interfere with seed germination. In this research the effect of light, gibberellins and paclobutrazol in coffee seed germination were evaluated. Seeds of coffee (Coffea arabica L.) from cultivar Rubi harvested at the developmental stage known as cherry were dried until 12% of water content. The first trial was performed in factorial design (2x2), the condtions being two (light and dark), presence and absence of gibberellins. The substrate was imbibed with 20 ml of GA3 (100 mM) and the control treatment with distillated water. The second trial was performed in factorial design (4x2x3), with four concentrations of paclobutrazol (0; 0,1;1,0; and 10 mM), two conditions (light and dark) and three storage conditions (0, 4 and 8 months). The substrate was imbibed with 20 mL of paclobutrazol and the control treatment with distillated water. Both trials were performed in four replications of fifty seeds. Seed sowing was performed in gerbox tray with two blotting papers and one germitest paper. The dark condition was created by wrapping the gerbox with an aluminum foil. The germiantion velocity rate, germination at thirty days and the time to 50% root protrusion were evaluated. The gibberellin treatment in seed coffee decreases the germination velocity rate and percentage of germination. The gibberellin inhibitor decreases the gemination velocity rate but it did not reduce the effect of light. High values of germination velocity rate were observed in dark.

Perception of consonant length by Russian and American listeners.

An experimental investigation of Russian geminates revealed that intervocalic, post‐stress, and word‐initial geminates have an earlier perceptual boundary in relation to the average singleton duration in these positions. This provides an articulatory and perceptual advantage for geminate production and discrimination, which may explain cross‐linguistic preference for these types of geminates. The proximity of the boundary to the average singleton means that a smaller articulatory effort is needed to reach the geminate status; its greater distance from the average geminate means that fewer intended geminates are misperceived as singletons, hence less danger of perceptually driven neutralization. To confirm that this generalization holds across languages a group of monolingual American English listeners was tested in addition to Russian listeners. The results strongly suggest that perception of the contrast between geminates and singletons has a linguistically universal basis. Speakers of American English—a language without phonemic consonant length—showed a pattern of responses very similar to that of the Russian listeners, in particular for post‐stress and intervocalic geminates. The consistency of the results in both languages further supports the hypothesis that the observed shift in perceptual boundary is responsible for cross‐linguistic dominance of intervocalic and post‐stress geminates.

Perception of Moroccan Arabic geminates by native English speakers.

Adult listeners often have difficulty perceiving phonetic distinctions that are not contrastive in their native language (e.g., Lisker and Abramson 1970, Miyawaki et al. 1975, Trehub 1976, MacKain et al. 1980, Werker et al. 1981, among others). However, the same contrast may be perceived with more or less difficulty depending on the environment in which it is embedded. This study investigated the perception of geminate consonants in Moroccan Arabic by native English speakers who had not had previous exposure to the geminate‐singleton contrast. The geminates [ss] and [zz] were paired with singleton counterparts in four different environments: medial‐intervocalic ([assa]‐[asa], [azza]‐[aza]); medial‐consonant‐adjacent ([assta]‐[asta], [azzda]‐[azda]); initial‐vowel‐adjacent ([ssa]‐[sa], [zza]‐[za]); and initial‐consonant‐adjacent ([ssta]‐[sta], [zzda‐[zda]]). The words were recorded by a native Moroccan Arabic speaker, and subsequently used as stimuli in a perception experiment (AX discrimination task; 80 participants). The sensitivity to the geminate‐singleton contrast was measured by calculating A‐prime scores (Grier 1971) and performing an ANOVA. The analysis showed a significant main effect of environment [F(3,237)=28.7; p<0.001]. The participants performed above chance, and their perception of the geminate‐singleton contrast was best in the medial‐intervocalic environment (A′=0.83), worse in the medial‐consonant‐adjacent (A′=0.73) and initial‐vowel‐adjacent environments (A′=0.74), and worst in the initial‐consonant‐adjacent context (A′=0.58).

Does the native language use of duration affect the perception of non‐native length contrasts?

This study compared native Italian (NI) and American English (NE) speakers’ abilities to perceive Japanese phonemic length contrasts. Japanese has both vowel and consonant length contrasts, Italian has only consonant length contrast, and English has neither. The study examined to which extent the differential use of duration in their native languages affects their abilities to perceive length contrasts in an unfamiliar language. Twenty‐two monolingual NI speakers perceived Japanese words in isolation and in sentences and were asked to identify the number of moras in target words, e.g., /o.do.t.ta/ as four moras. Their test scores were compared to those of 18 NE participants [Hirata (2004)] in an analysis of variance. Group (NE, NI) was a between‐subjects factor, and context (isolation, sentences) and word type (long vowels, geminates, combination, and short segments) were within‐subjects factors. While there was no main effect of group (NI: 44.6%; NE: 39.5%), there was a significant three‐way interaction....

Heterojunction topology versus fill factor correlations in novel hybrid small-molecular/polymeric solar cells

The authors present organic photovoltaic (OPV) devices comprising a small molecule electron acceptor based on 2-vinyl-4,5-dicyanoimidazole (Vinazene) and a soluble poly(p-phenylenevinylene) derivative as the electron donor. A strong dependence of the fill factor (FF) and the external quantum efficiency [incident photons converted to electrons (IPCE)] on the heterojunction topology is observed. As-prepared blends provided relatively low FF and IPCE values of 26% and 4.5%, respectively, which are attributed to significant recombination of geminate pairs and free carriers in a highly intermixed blend morphology. Going to an all-solution processed bilayer device, the FF and IPCE dramatically increased to 43% and 27%, respectively. The FF increases further to 57% in devices comprising thermally deposited Vinazene layers where there is virtually no interpenetration at the donor/acceptor interface. This very high FF is comparable to values reported for OPV using fullerenes as the electron acceptor. Furthermore, the rather low electron affinity of Vinazene compound near 3.5 eV enabled a technologically important open circuit voltage (V(oc)) of 1.0 V.

Radical pairs with rotational fluidity in the photochemical reaction of acetophenone and cyclohexane in the zeolite NAY: a 13C CPMAS NMR and product analysis study

The photochemical reaction of acetophenone and cyclohexane in the zeolite NaY occurs by combination of the geminate radical pairs to give products that reveal a significant amount of rotational fluidity, which was also documented by intermolecular nuclear dipolar interaction measurements using cross polarization (13)C NMR (CPMAS) experiments.

On the assimilation of Russian substantival lexemes in Karelian

This study addresses the borrowing of substantival lexical elements from Russian into Karelian, a Baltic Finnic language spoken in northwest Russia. The large Russian component in Karelian is the result of centuries of intensive contact between the two peoples. Various aspects of the ‘Karelianizing’ process are examined here, including consonant cluster simplification and modification, vowel harmony and length, consonant length and gemination, and such morphological questions as the treatment of Russian affixes and the need for a word-final vowel in the new Karelian forms.

Radical cage effects: A method for measuring recombination efficiencies of secondary geminate radical cage pairs using pump-probe transient absorption methods

A method is reported for measuring the recombination efficiency of secondary geminate radical cage pairs. The procedure involves measuring the recombination efficiency for primary geminate recombination (F(c1)) using pump-probe laser methods and measuring the "apparent" (or net) recombination efficiency (F(cP)) for all geminate pairs (primary and secondary) using steady-state irradiation methods. A mathematical relationship between F(cP), F(c1), and F(c2) (where F(c2) is the recombination efficiency for secondary geminate recombination) is derived and demonstrated using the photolysis reactions of the [(CpR)Mo(CO)(3)](2) molecules, where CpR = eta(5)-C(5)H(4)CH(3) and eta(5)-C(5)H(4)(CH(2))(2)C(O)NCH(3)(CH(2))(n)CH(3) (n = 3, 8, 13, 18). As an example of the results obtained using the new method, it was found that F(c1) = 0.43 and F(c2) = 0.68 for the molecule with CpR = eta(5)-C(5)H(4)CH(2)CH(2)N(CH(3))C(O)(CH(2))(18)CH(3). The value of F(c2) decreased as the side-chain on the Cp ring got shorter; F(c2) is equal to 0.0 for the molecules with n = 3 and for CpR = eta(5)-C(5)H(4)CH(3). It is hypothesized that a longer side-chain prevents facile diffusion of the radicals out of the secondary cage, whereas the smaller side-chains permit more facile diffusion apart of the radicals. A general conclusion is that the reactions of large radicals in particular may be especially impacted by secondary geminate cage recombination.