bluuebunny/crossref_metadata_2025 huggingface dataset:
Focusing-enhanced mixing in microfluidic channels
Authors: Zhang Zhiyi , Zhao Ping , Xiao Gaozhi , Lin Min , Cao Xudong
Published: March 2008

A focusing-based microfluidic mixer was studied. The micromixer utilizes the focusing process required for cytometry to reduce the diffusion distance of molecules to be mixed in order to facilitate the passive diffusion-controlled mixing process. It was found that both the high flow rate ratio of the sheath flow to the flows to be mixed and the low flow rate of the mixing fluids resulted in the short mixing length required within the microfluidic channel. It was shown that a complete mixing was achieved within a distance of 4 mm in the micromixer for the focused mixing fluids at a flow rate of 2 μl/min and a flow rate ratio of the sheath flow to the flows to be mixed at 4:1. The mixer described here is simple and can be easily fabricated and controlled.
Effects of substrates on photocurrents from photosensitive polymer coated carbon nanotube networks
Authors: Shi Yumeng , Tantang Hosea , Lee Chun Wei , Weng Cheng-Hui , Dong Xiaochen , Li Lain-Jong , Chen Peng
Published: March 2008

We investigated the substarte (SiO2 and quartz) effects on the photoresponsitivity of photosensitive polymer coated single-walled carbon nanotube (SWNT) networks. As charge trapping on quartz surface is believed to be much less significant than that observed on conventional SiO2 dielectrics, using quartz as the supporting substrate allows us to probe the naïve photointeraction between the photosensitive polymers and SWNTs. The two-terminal SWNT resistor devices on quartz provide an effective yet simple methodology to discriminate electron- or hole-donating photosensitive polymers.
Nanofluids with plasma treated diamond nanoparticles
Authors: Yu Qingsong , Kim Young Jo , Ma Hongbin
Published: March 2008

In this study, diamond nanoparticles were plasma treated by glow discharges of methane and oxygen with an aim of improving their dispersion characteristics in a base fluid of water and enhancing the thermal conductivity of the resulting nanofluids. It was found that, after plasma treatment, stable nanofluids with improved thermal conductivity were obtained without using any stabilizing agents. With <0.15vol% addition of plasma treated nanoparticles into water, a 20% increase in thermal conductivity was achieved and a 5%–10% increase in both fluid density and viscosity was observed.
Optical property and spectroscopy studies on the explosive 2,4,6-trinitro-1,3,5-trihydroxybenzene in the terahertz range
Authors: Zhou Qing-li , Zhang Cun-lin , Mu Kai-jun , Jin Bin , Zhang Liang-liang , Li Wei-wei , Feng Rui-shu
Published: March 2008

Using the terahertz time-domain spectroscopy, the complex refraction index and dielectric function of the pure 2,4,6-trinitro-1,3,5-trihydroxybenzene (TNPG) are calculated with the obtained parameters of the pure polyethylene (PE) and a mixture of TNPG and PE based on the Bruggeman effective medium theory. The theoretical investigation consistent with the experimental data in the vibration spectra of TNPG is presented in the range of 0.2–2.5THz. The results reveal that the two absorption features identified as the fingerprint of TNPG in our studied range are mainly dominated by the intramolecular collective vibration modes.
Molecular understanding of the deposition of gold nanoclusters on TiO2(110)
Authors: Zeng Q. H. , Wong K. , Jiang X. C. , Yu A. B.
Published: March 2008

The deposition of gold nanoclusters on rutile TiO2(110) surface is investigated by molecular dynamics simulation, with special reference to the effects of surface defect types (i.e., point, step, and groove) and deposition temperature. The results show that gold nanoclusters can be strongly attracted to the surface and a higher degree of defect results in a stronger attractive interaction. In addition, the aggregation behavior of gold nanoclusters is studied by simulation and experiment. The results indicate that the aggregation can be effectively controlled by introducing suitable surface defects or adding citrate ions into the solution. The findings are useful to the design and fabrication of supported Au–TiO2 catalysts with high catalytic activity.
Oestrogen and progesterone receptor binding capacity and oestrogen receptor alpha expression (ERα mRNA) along the cervix of cycling ewes
Authors: Rodríguez-Piñón M. , Tasende C. , Puime P. , Garófalo E. G.
Published: March 2008

The aim of the present work was to study the oestrogen receptor (ER) and progesterone receptor (PR) binding capacity and the oestrogen receptor alpha (ERα) mRNA concentration in cranial and caudal cervix during the ovine oestrous cycle. Cervical samples of synchronised Corriedale ewes were obtained on Day 1 (n = 7), 6 (n = 6) or 13 (n = 7) after oestrus detection (Day 0). The ER and PR binding capacity by ligand-binding assay and the ERα mRNA concentration by solution hybridisation in both cranial and caudal zones of the cervix were determined. The ER and PR binding capacity were higher (P < 0.005) on Day 1 than on Days 6 and 13 in both cranial and caudal zones. The ERα mRNA concentrations were higher (P < 0.0001) on Day 1 than on Days 6 and 13 only in the caudal zone. The PR binding capacity and ERα mRNA concentration were higher (P < 0.005) in the caudal than in the cranial zone on Day 1. The ER and PR expression in the ovine cervix varied during the oestrous cycle in agreement with the known upregulation exerted by oestrogen and downregulation exerted by progesterone. Differences in ER and PR expression along the longitudinal axis of the ovine cervix were found, reflecting histological and functional differences between the cranial and caudal zones.
Relationships of basal metabolic rate, relative testis size and cycle length of spermatogenesis in shrews (Mammalia, Soricidae)
Authors: Parapanov Roumen , Nusslé Sébastien , Hausser Jacques , Vogel Peter
Published: March 2008

The aim of the present study was to determinate the cycle length of spermatogenesis in three species of shrew, Suncus murinus, Sorex coronatus and Sorex minutus, and to assess the relative influence of variation in basal metabolic rate (BMR) and mating system (level of sperm competition) on the observed rate of spermatogenesis, including data of shrew species studied before (Sorex araneus, Crocidura russula and Neomys fodiens). The dynamics of sperm production were determined by tracing 5-bromodeoxyuridine in the DNA of germ cells. As a continuous scaling of mating systems is not evident, the level of sperm competition was evaluated by the significantly correlated relative testis size (RTS). The cycle durations estimated by linear regression were 14.3 days (RTS 0.3%) in Suncus murinus, 9.0 days (RTS 0.5%) in Sorex coronatus and 8.5 days (RTS 2.8%) in Sorex minutus. In regression and multiple regression analyses including all six studied species of shrew, cycle length was significantly correlated with BMR (r2 = 0.73) and RTS (r2 = 0.77). Sperm competition as an ultimate factor obviously leads to a reduction in the time of spermatogenesis in order to increase sperm production. BMR may act in the same way, independently or as a proximate factor, revealed by the covariation, but other factors (related to testes size and thus to mating system) may also be involved.
A 16-bit parallel processing in a molecular assembly
Authors: Bandyopadhyay Anirban , Acharya Somobrata
Published: March 2008

A machine assembly consisting of 17 identical molecules of 2,3,5,6-tetramethyl-1–4-benzoquinone (DRQ) executes 16 instructions at a time. A single DRQ is positioned at the center of a circular ring formed by 16 other DRQs, controlling their operation in parallel through hydrogen-bond channels. Each molecule is a logic machine and generates four instructions by rotating its alkyl groups. A single instruction executed by a scanning tunneling microscope tip on the central molecule can change decisions of 16 machines simultaneously, in four billion (4
16
) ways. This parallel communication represents a significant conceptual advance relative to today's fastest processors, which execute only one instruction at a time.
Comparing bird and human soaring strategies
Authors: Ákos Zsuzsa , Nagy Máté , Vicsek Tamás
Published: March 2008

Gliding saves much energy, and to make large distances using only this form of flight represents a great challenge for both birds and people. The solution is to make use of the so-called thermals, which are localized, warmer regions in the atmosphere moving upwards with a speed exceeding the descent rate of bird and plane. Whereas birds use this technique mainly for foraging, humans do it as a sporting activity. Thermalling involves efficient optimization including the skilful localization of thermals, trying to guess the most favorable route, estimating the best descending rate, etc. In this study, we address the question whether there are any analogies between the solutions birds and humans find to handle the above task. High-resolution track logs were taken from thermalling falcons and paraglider pilots to determine the essential parameters of the flight patterns. We find that there are relevant common features in the ways birds and humans use thermals. In particular, falcons seem to reproduce the MacCready formula widely used by gliders to calculate the best slope to take before an upcoming thermal.
Microbial community gene expression in ocean surface waters
Authors: Frias-Lopez Jorge , Shi Yanmei , Tyson Gene W. , Coleman Maureen L. , Schuster Stephan C. , Chisholm Sallie W. , DeLong Edward F.
Published: March 2008

Metagenomics is expanding our knowledge of the gene content, functional significance, and genetic variability in natural microbial communities. Still, there exists limited information concerning the regulation and dynamics of genes in the environment. We report here global analysis of expressed genes in a naturally occurring microbial community. We first adapted RNA amplification technologies to produce large amounts of cDNA from small quantities of total microbial community RNA. The fidelity of the RNA amplification procedure was validated with
Prochlorococcus
cultures and then applied to a microbial assemblage collected in the oligotrophic Pacific Ocean. Microbial community cDNAs were analyzed by pyrosequencing and compared with microbial community genomic DNA sequences determined from the same sample. Pyrosequencing-based estimates of microbial community gene expression compared favorably to independent assessments of individual gene expression using quantitative PCR. Genes associated with key metabolic pathways in open ocean microbial species—including genes involved in photosynthesis, carbon fixation, and nitrogen acquisition—and a number of genes encoding hypothetical proteins were highly represented in the cDNA pool. Genes present in the variable regions of
Prochlorococcus
genomes were among the most highly expressed, suggesting these encode proteins central to cellular processes in specific genotypes. Although many transcripts detected were highly similar to genes previously detected in ocean metagenomic surveys, a significant fraction (≈50%) were unique. Thus, microbial community transcriptomic analyses revealed not only indigenous gene- and taxon-specific expression patterns but also gene categories undetected in previous DNA-based metagenomic surveys.
Heritability of cooperative behavior in the trust game
Authors: Cesarini David , Dawes Christopher T. , Fowler James H. , Johannesson Magnus , Lichtenstein Paul , Wallace Björn
Published: March 2008

Although laboratory experiments document cooperative behavior in humans, little is known about the extent to which individual differences in cooperativeness result from genetic and environmental variation. In this article, we report the results of two independently conceived and executed studies of monozygotic and dizygotic twins, one in Sweden and one in the United States. The results from these studies suggest that humans are endowed with genetic variation that influences the decision to invest, and to reciprocate investment, in the classic trust game. Based on these findings, we urge social scientists to take seriously the idea that differences in peer and parental socialization are not the only forces that influence variation in cooperative behavior.
In vivo
correction of a Menkes disease model using antisense oligonucleotides
Authors: Madsen Erik C. , Morcos Paul A. , Mendelsohn Bryce A. , Gitlin Jonathan D.
Published: March 2008

Although the molecular basis of many inherited metabolic diseases has been defined, the availability of effective therapies in such disorders remains problematic. Menkes disease is a fatal neurodegenerative disorder due to loss-of-function mutations in the
ATP7A
gene encoding a copper-transporting P-type Atpase. To develop therapeutic approaches in affected patients, we have identified a zebrafish model of Menkes disease termed
calamity
that results from splicing defects in the zebrafish orthologue of the
ATP7A
gene. Embryonic-recessive lethal mutants have impaired copper homeostasis that results in absent melanin pigmentation, impaired notochord formation, and hindbrain neurodegeneration. In this current study, we have attempted to rescue these striking phenotypic alterations by using a series of antisense morpholino oligonucleotides directed against the splice-site junctions of two mutant
calamity
alleles. Our findings reveal a robust and complete correction of the copper-deficient defects of
calamity
in association with the generation of the WT Menkes protein in all rescued mutants. Interestingly, a quantitative analysis of
atp7a
-specific transcripts suggests that competitive translational regulation may account for the synthesis of WT protein in these embryos. This
in vivo
correction of Menkes disease through the rescue of aberrant splicing may provide therapeutic options in this fatal disease and illustrates the potential for zebrafish models of human genetic disease in the development of treatments based on the principles of interactions of synthetic oligonucleotide analogues with mRNA.
Barley grain with adhering hulls is controlled by an ERF family transcription factor gene regulating a lipid biosynthesis pathway
Authors: Taketa Shin , Amano Satoko , Tsujino Yasuhiro , Sato Tomohiko , Saisho Daisuke , Kakeda Katsuyuki , Nomura Mika , Suzuki Toshisada , Matsumoto Takashi , Sato Kazuhiro , Kanamori Hiroyuki , Kawasaki Shinji , Takeda Kazuyoshi
Published: March 2008

In contrast to other cereals, typical barley cultivars have caryopses with adhering hulls at maturity, known as covered (hulled) barley. However, a few barley cultivars are a free-threshing variant called naked (hulless) barley. The covered/naked caryopsis is controlled by a single locus (
nud
) on chromosome arm 7HL. On the basis of positional cloning, we concluded that an ethylene response factor (ERF) family transcription factor gene controls the covered/naked caryopsis phenotype. This conclusion was validated by (
i
) fixation of the 17-kb deletion harboring the ERF gene among all 100 naked cultivars studied; (
ii
) two x-ray-induced
nud
alleles with a DNA lesion at a different site, each affecting the putative functional motif; and (
iii
) gene expression strictly localized to the testa. Available results indicate the monophyletic origin of naked barley. The
Nud
gene has homology to the
Arabidopsis WIN1
/
SHN1
transcription factor gene, whose deduced function is control of a lipid biosynthesis pathway. Staining with a lipophilic dye (Sudan black B) detected a lipid layer on the pericarp epidermis only in covered barley. We infer that, in covered barley, the contact of the caryopsis surface, overlaid with lipids to the inner side of the hull, generates organ adhesion.
Optical measurement of synaptic glutamate spillover and reuptake by linker optimized glutamate-sensitive fluorescent reporters
Authors: Hires Samuel Andrew , Zhu Yongling , Tsien Roger Y.
Published: March 2008

Genetically encoded sensors of glutamate concentration are based on FRET between cyan and yellow fluorescent proteins bracketing a bacterial glutamate-binding protein. Such sensors have yet to find quantitative applications in neurons, because of poor response amplitude in physiological buffers or when expressed on the neuronal cell surface. We have improved our glutamate-sensing fluorescent reporter (GluSnFR) by systematic optimization of linker sequences and glutamate affinities. Using SuperGluSnFR, which exhibits a 6.2-fold increase in response magnitude over the original GluSnFR, we demonstrate quantitative optical measurements of the time course of synaptic glutamate release, spillover, and reuptake in cultured hippocampal neurons with centisecond temporal and spine-sized spatial resolution. During burst firing, functionally significant spillover persists for hundreds of milliseconds. These glutamate levels appear sufficient to prime NMDA receptors, potentially affecting dendritic spike initiation and computation. Stimulation frequency-dependent modulation of spillover suggests a mechanism for nonsynaptic neuronal communication.
Categorical perception of color is lateralized to the right hemisphere in infants, but to the left hemisphere in adults
Authors: Franklin A. , Drivonikou G. V. , Bevis L. , Davies I. R. L. , Kay P. , Regier T.
Published: March 2008

Both adults and infants are faster at discriminating between two colors from different categories than two colors from the same category, even when between- and within-category chromatic separation sizes are equated. For adults, this categorical perception (CP) is lateralized; the category effect is stronger for the right visual field (RVF)–left hemisphere (LH) than the left visual field (LVF)–right hemisphere (RH). Converging evidence suggests that the LH bias in color CP in adults is caused by the influence of lexical color codes in the LH. The current study investigates whether prelinguistic color CP is also lateralized to the LH by testing 4- to 6-month-old infants. A colored target was shown on a differently colored background, and time to initiate an eye movement to the target was measured. Target background pairs were either from the same or different categories, but with equal target-background chromatic separations. Infants were faster at initiating an eye movement to targets on different-category than same-category backgrounds, but only for targets in the LVF–RH. In contrast, adults showed a greater category effect when targets were presented to the RVF–LH. These results suggest that whereas color CP is stronger in the LH than RH in adults, prelinguistic CP in infants is lateralized to the RH. The findings suggest that language-driven CP in adults may not build on prelinguistic CP, but that language instead imposes its categories on a LH that is not categorically prepartitioned.
Language affects patterns of brain activation associated with perceptual decision
Authors: Tan Li Hai , Chan Alice H. D. , Kay Paul , Khong Pek-Lan , Yip Lawrance K. C. , Luke Kang-Kwong
Published: March 2008

Well over half a century ago, Benjamin Lee Whorf [Carroll JB (1956)
Language, Thought, and Reality: Selected Writings of Benjamin Lee Whorf
(MIT Press, Cambridge, MA)] proposed that language affects perception and thought and is used to segment nature, a hypothesis that has since been tested by linguistic and behavioral studies. Although clear Whorfian effects have been found, it has not yet been demonstrated that language influences brain activity associated with perception and/or immediate postperceptual processes (referred hereafter as “perceptual decision”). Here, by using functional magnetic resonance imaging, we show that brain regions mediating language processes participate in neural networks activated by perceptual decision. When subjects performed a perceptual discrimination task on easy-to-name and hard-to-name colored squares, largely overlapping cortical regions were identified, which included areas of the occipital cortex critical for color vision and regions in the bilateral frontal gyrus. Crucially, however, in comparison with hard-to-name colored squares, perceptual discrimination of easy-to-name colors evoked stronger activation in the left posterior superior temporal gyrus and inferior parietal lobule, two regions responsible for word-finding processes, as demonstrated by a localizer experiment that uses an explicit color patch naming task. This finding suggests that the language-processing areas of the brain are directly involved in visual perceptual decision, thus providing neuroimaging support for the Whorf hypothesis.
Kuru prions and sporadic Creutzfeldt–Jakob disease prions have equivalent transmission properties in transgenic and wild-type mice
Authors: Wadsworth Jonathan D. F. , Joiner Susan , Linehan Jacqueline M. , Desbruslais Melanie , Fox Katie , Cooper Sharon , Cronier Sabrina , Asante Emmanuel A. , Mead Simon , Brandner Sebastian , Hill Andrew F. , Collinge John
Published: March 2008

Kuru provides our principal experience of an epidemic human prion disease and primarily affected the Fore linguistic group of the Eastern Highlands of Papua New Guinea. Kuru was transmitted by the practice of consuming dead relatives as a mark of respect and mourning (transumption). To date, detailed information of the prion strain type propagated in kuru has been lacking. Here, we directly compare the transmission properties of kuru prions with sporadic, iatrogenic, and variant Creutzfeldt–Jakob disease (CJD) prions in
Prnp
-null transgenic mice expressing human prion protein and in wild-type mice. Molecular and neuropathological data from these transmissions show that kuru prions are distinct from variant CJD and have transmission properties equivalent to those of classical (sporadic) CJD prions. These findings are consistent with the hypothesis that kuru originated from chance consumption of an individual with sporadic CJD.
The RCK1 high-affinity Ca
2+
sensor confers carbon monoxide sensitivity to Slo1 BK channels
Authors: Hou Shangwei , Xu Rong , Heinemann Stefan H. , Hoshi Toshinori
Published: March 2008

Carbon monoxide (CO) is a lethal gas, but it is also increasingly recognized as a physiological signaling molecule capable of regulating a variety of proteins. Among them, large-conductance Ca
2+
- and voltage-gated K
+
(Slo1 BK) channels, important in vasodilation and neuronal firing, have been suggested to be directly stimulated by CO. However, the molecular mechanism of the stimulatory action of CO on the Slo1 BK channel has not been clearly elucidated. We report here that CO reliably and repeatedly activates Slo1 BK channels in excised membrane patches in the absence of Ca
2+
in a voltage-sensor-independent manner. The stimulatory action of CO on the Slo1 BK channel requires an aspartic acid and two histidine residues located in the cytoplasmic RCK1 domain, and the effect persists under the conditions known to inhibit the conventional interaction between CO and heme in other proteins. We propose that CO acts as a partial agonist for the high-affinity divalent cation sensor in the RCK1 domain of the Slo1 BK channel.
Human HLTF functions as a ubiquitin ligase for proliferating cell nuclear antigen polyubiquitination
Authors: Unk Ildiko , Hajdú Ildikó , Fátyol Károly , Hurwitz Jerard , Yoon Jung-Hoon , Prakash Louise , Prakash Satya , Haracska Lajos
Published: March 2008

Human helicase-like transcription factor (HLTF) is frequently inactivated in colorectal and gastric cancers. Here, we show that HLTF is a functional homologue of yeast Rad5 that promotes error-free replication through DNA lesions. HLTF and Rad5 share the same unique structural features, including a RING domain embedded within a SWI/SNF helicase domain and an HIRAN domain. We find that inactivation of HLTF renders human cells sensitive to UV and other DNA-damaging agents and that HLTF complements the UV sensitivity of a
rad5
Δ yeast strain. Also, similar to Rad5, HLTF physically interacts with the Rad6–Rad18 and Mms2–Ubc13 ubiquitin-conjugating enzyme complexes and promotes the Lys-63-linked polyubiquitination of proliferating cell nuclear antigen at its Lys-164 residue. A requirement of HLTF for error-free postreplication repair of damaged DNA is in keeping with its cancer-suppression role.
A Joint Strategic Plan for Management of Great Lakes fisheries: A cooperative regime in a multi-jurisdictional setting
Authors: Gaden Marc , Krueger Charles , Goddard Christopher , Barnhart Gerald
Published: March 2008

Two nations, eight states, the province of Ontario, two U.S. intertribal authorities, and the binational Great Lakes Fishery Commission all play a role in managing the Great Lakes fishery. No overarching institution has the authority to compel cross-border cooperation. Rather, the fishery agencies adhere to A Joint Strategic Plan for Management of Great Lakes Fisheries, a voluntary, multi-jurisdictional agreement signed in 1981. This article provides a brief overview of the roles and responsibilities of the management jurisdictions and describes how the Joint Strategic Plan helps agencies cooperate across jurisdictional boundaries. The plan relies on four strategies—consensus, accountability, information sharing, and ecosystem management—to foster cooperation, and to operationalize collective action on both lake and technical committees. The plan is a model for multi-jurisdictional cooperation in a politically fragmented region.
Changes in species composition and abundance of commercially important pelagic fish species in Kigoma area, Lake Tanganyika, Tanzania
Authors: Kimirei I. A. , Mgaya Y. D. , Chande A. I.
Published: March 2008

The pelagic fishery of Lake Tanganyika provides employment to about 1 million consumers and protein to many more people living around the lake. It is mainly based on three commercially important fish species namely two clupeids Stolothrissa tanganicae and Limnothrissa miodon commonly known as “dagaa” and a perch Lates stappersii. A declining trend of the perch both in its composition and abundance in the pelagic fish landings is partly tied to local over-fishing and climate change. There are three important periods in the exploitation process identified as: (1) a traditional fishery period, the pre-1975 period marked by low catches of Lates spp. and a dominance of clupeids; (2) an industrial fishery period (1975–1978) marked by high catches of Lates stappersii and high total landings; and (3) an artisanal fishery period (post 1984) with relatively low catches and high dominance of clupeids especially Stolothrissa tanganicae. Population growth and refugee influx from the politically volatile Burundi and Democratic Republic of Congo both caused high fish protein demand, particularly for dried clupeids. Also changes in the rural economy caused by drought in the area are resulting into high exploitation pressure on the pelagic resources. Concerted efforts to prevent/reduce exploitation pressure on the pelagic fish resources should take into action a lake wide management strategy where by management issues in all the riparian countries should be harmonized. More effort should be geared towards preventing the use of beach seines and small meshed nets subsequently ensuring a sustainable utilization of the pelagic fish resources.
Ecological state and monitoring of limnological and biological parameters in Lake Ladoga, Russia
Authors: Viljanen Markku , Drabkova Valentina , Avinsky Valentin , Kapustina Larisa , Raspletina Galina
Published: March 2008

Lake Ladoga (17 891 km2) is the largest lake in Europe, with a 258 000 km2drainage area that extends to much of north-western European Russia and eastern Finland. Its ecosystem has been systematically investigated since 1976, and sporadically since the 1950s. Monitoring programmes have included studies on its hydrology, water chemistry and biology (phytoplankton, bacterioplankton, zooplankton, benthos, macrophytes and fish). The sampling frequency per vegetation season (spring, summer and autumn) has varied from 2 to 6 times, and samples have been collected at 20–60 fixed stations in the different zones of the lake. These long-term investigations covering over 40 years serve as a good basis for understanding the processes taking place in Lake Ladoga, as well as for assessing the changes and current environmental conditions.

Until the early 1960s, Lake Ladoga was oligotrophic and characterized by good water quality; but within the past 30 years, as a result of human impact, its ecological state seems to have deteriorated. Especially since the 1970s, its trophic state has changed to mesotrophic, with elevated nutrient concentrations, reduced transparency and poorer fish catches, together with structural changes in its plankton, zoobenthos and fish communities. During the last decades, several planktonic, benthic and fish species that are sensitive to eutrophication have disappeared. Conditions in the whole lake, and especially at some of the worst-polluted sites, have actually improved in recent years, however, due to the closing of some of the sources of industrial pollution, and some signs of a recovery have been observed. The present species composition points to mesotrophic and eutrophic conditions in the coastal regions, but mainly oligo-mesotrophic conditions in the pelagic areas.

The aim of this paper is to describe and assess monitoring practices in Lake Ladoga and the results obtained, future prospects, changes that have occurred and the current state of the ecosystems.
Immediate Memory and Simultaneous Stimuli
Authors: Broadbent D. E.
Published: March 2008

When two sets of digits are presented simultaneously one to one ear and one to the other, the subject may be asked to write them down from immediate memory beginning with those on an ear chosen by the experimenter. He can do this, but any mistakes are usually amongst those on the ear prescribed for later response. If the subject does not know the order of recall until after stimulation, he either shows low efficiency with the same serial order effect, or else normal efficiency with an altered serial order effect.

When the order of recall is known in advance, efficiency is also reduced by altering the time of presentation of the last items to be recalled; and also by inserting irrelevant items. All these facts are consistent with a particular theory of immediate memory.
The Effect upon Monaural Sensitivity of Continuous Stimulation of the opposite Ear
Authors: Ingham J. G.
Published: March 2008

The threshold to a 1,000 c./sec. tone presented to the left ear was measured whilst the right ear was under continuous stimulation by a 400 c./sec. tone. Observations were made, on different groups of subjects, under three stimulus conditions and two conditions of attention. Thresholds were found to increase with increasing intensities of the continuous tone. Attention to that part of the field associated with the continuous stimulus produced no significant change, whether the continuous stimulus was present or not. There were no significant after-effects during ten minutes following the end of the continuous stimulus, though the results suggested a slow decrease in threshold.

Several explanations of the phenomenon are considered. Cross-hearing and the reflex contraction of the middle-ear muscles can be virtually excluded. Central inhibition or the central control of sensory end-organs can account for the results. A statistical hypothesis is also tenable.
Reducing Interference in Forgetting
Authors: Summerfield Arthur , Steinberg Hannah
Published: March 2008

According to interference theories forgetting results from the intervention of extraneous associations which disturb the patterns built up during learning. It also seems that the period immediately following learning is critical for forgetting. The experiment which is described was carried out to investigate whether administration of the central-depressant drug nitrous oxide immediately after learning would reduce forgetting, since it had been shown to impair the formation of associations and ought therefore to reduce interference. This expectation was borne out, significantly less forgetting occurring when nitrous oxide was given than when air was given. A possible physiological basis, relating these results to those for sleep is discussed.
The Developmental Study of Apparent Movement
Authors: Brenner May Woolf
Published: March 2008

Differences in thresholds of apparent simultaneity and apparent movement were observed with normal and brain-damaged children of different ages. In an attempt to explore this relationship more fully, III subjects between 2 ½ years and 19 years were tested on a modified Withers tachistoscope. It was found that changes in thresholds of apparent simultaneity and apparent movement were clearly a function of age. Both illusions were seen under objectively more difficult conditions—slower flash frequencies—by younger children. The decrease of the illusions with age continued until about 14 years, and then levelled off. No sex differences were observed. A second investigation of closure ability indicated that an explanation of the apparent movement changes in terms of greater closure ability in younger children was not tenable, since ability to form a gestalt under difficult conditions increased as a function of age. In the light of other investigations on age and illusions it is possible that the change in apparent movement is due to an increase of discrimination with age. On the other hand, the similarity between the frequency of apparent-movement thresholds and dominant brain rhythms, as well as their parallel changes with age, may point to some more basic neurophysiological growth change.
Periodicity of Response in Operant Extinction
Authors: Hurwitz H. M. B.
Published: March 2008

The distribution of responses during experimental extinction trials for a group of 11 rats, trained in the Skinner-box, was examined. Our analysis supports an earlier suggestion that the extinction trial may be separated into respondent and silent periods. Response rates during respondent periods show relatively little decline throughout the extinction period investigated, whereas silent periods increase with positive acceleration. The traditional exponential function used to describe response rates during experimental extinction trials should therefore be regarded as a very rough approximation to the mathematical characteristics of the animal's behaviour. Its use as a basis for quantifying critical intervening variables, such as habit strength or behaviour potentiality, is consequently seriously challenged.
Transfer Effects in Reactions to “Stress”
Authors: Steinberg Hannah , Russell Roger W.
Published: March 2008

In a previous investigation we showed that, when human subjects were exposed to the stress of an insoluble problem while under the influence of nitrous oxide, the usual adverse effects of the stress on subsequent learning were abolished. We suggested that these empirical results might be accounted for either in terms of “anxiety-reduction” or in terms of transfer effects.

The results of the present experiment show that differential transfer effects do occur in the insoluble problem situation when the degree of similarity of this task to the subsequent soluble task is varied. They also show that inhalation of nitrous oxide during exposure to the insoluble task abolishes these differential transfer effects, as well as any other effects which may be interfering with subsequent learning. These other effects, if they are present, may include “anxiety” and other “unique properties” referred to by other investigators using the insoluble problem situation in experimental studies of stress.
The Measurement of Elements in an Assembly Task-The Information Output of the Human Motor System
Authors: Annett J. , Golby C. W. , Kay H.
Published: March 2008

The performance of three well-practised subjects on an assembly task was analysed using both an electrical contact technique and high-speed film recording. The task consisted of transferring a row of pegs into a parallel row of holes 8 inches away. There were four variations in the diameter of the holes presenting different degrees of difficulty. An information analysis of the output of the motor response, based on a formula suggested by Fitts, was applied to the data. Differences both in the measuring techniques and in the way the information analysis was applied raised problems which have an important bearing on the thesis of the constancy of human channel capacity and on the possible use of information measures in analysing motor tasks. Discrepancies between the photographic and the contact analysis as techniques for defining Movement Loaded and Positioning elements were examined. Whilst the contact analysis showed movement time increasing with decreasing target tolerance the film analysis showed gross movement time to be constant and the variation due to difficulty confined to the relatively small secondary positioning movement. An attempt to analyse the information load on gross and secondary movement respectively indicated that gross movement was made to an area of 2 in. in diameter about the actual target irrespective of its size and that secondary movement began as this target was entered. Values for information transmission rate were found to be constant when based on the individual element times from the photographic analysis but different transmission rates were found when calculations were based on overall times. Finally some assumptions underlying the formula are examined and it is pointed out that other rational assumptions when applied to these data would lead to results which would not support the thesis of the constancy of human channel capacity.
Visual Discrimination of Shape by Octopus. Squares and Triangles
Authors: Sutherland N. S.
Published: March 2008

An experiment was performed upon visual discrimination of shape by the octopus in order to test two predictions derived from a theory of visual discrimination of orientation and shape. Two groups of octopuses were trained to discriminate between a square and a triangle and between a diamond and a triangle. It was found that octopuses discriminate more readily between a square with base horizontal and a triangle than between a diamond and a triangle. Transfer tests showed that: (1) For the octopus, an upright and an inverted triangle have more equivalence than a diamond and a square with base horizontal. (2) Octopuses do not discriminate between the figures used by analysing only differences in one part of the figures (e.g. bases or tops). (3) Having learned the initial discrimination, octopuses transfer to both larger and smaller figures. (4) A pentagon has more equivalence to a square or diamond than to a triangle. (5) A circle is not treated as equivalent to a square. The results are taken to be in agreement with the theory that octopuses analyse the vertical and lateral extents of figures, and that shape discrimination is achieved by analysing the changes in the rates of change in the firing of neurons representing the vertical and lateral extents of the shapes. The results are shown to differ from those obtained with birds and rats, but to agree with results found for higher mammals where these are available for comparison.
An Experimental Synthesis of the Associations and Gestalt Accounts of the Perception of Size: Part I
Authors: Joynson R. B.
Published: March 2008

The Associationists state that our everyday impressions of size are a product of past experience. The Gestalt psychologists state that they are immediately or directly given in present experience. The experiment described here suggests that both past and present experience are simultaneously involved, and that a synthesis of the two accounts is required.
Visual Illusions Viewed as Stabilized Retinal Images
Authors: Pritchard R. M.
Published: March 2008

Some well-known visual illusions have been examined under conditions which remove the effect of eye movements so that the image on the retina is stationary. Under these conditions the simple geometrical illusions are perceived in the normal way. Ambiguous perceptive figures show the reversals at about the usual rate provided that the subject is able to direct his attention to a salient point of the pattern. Certain regular stationary patterns produce illusory shadows which appear to move across the pattern in normal vision. These shadows are not seen when the effect of eye movements is removed.
A Study of Evaluative Problem Solving Part I. Observations on Adults
Authors: Rayner E. H.
Published: March 2008

Six young adults were observed playing each other at a league type series of the board game pegity. This gave an opportunity to observe the development of strategies in the play. Some systematic errors in the play were also investigated.
A Study of Evaluative Problem Solving: Part II. Developmental Observations
Authors: Rayner E. H.
Published: March 2008

A previous article in this journal described observations on six young adults playing the board game pegity. The following article continues this description with observations on six children at each of the age levels five, seven, eleven and fifteen playing a league type series of pegity games. This gave the opportunity to observe the development of strategies of play both with age and with experience of the game. Special attention was paid to changes that took place between the ages of five and seven. Systematic errors were also observed. An explanation of some adult errors in developmental terms was attempted.
Double Drive Learning in Rats without Previous Selective Reinforcement
Authors: Deutsch J. A.
Published: March 2008

Can rats which have never been selectively satiated by food or water respond appropriately by choosing the relevant reward when they are made hungry or thirsty ? A group of 21 rats was put on a diet of wet mash and trained both hungry and thirsty in a T-maze with water on one side and food on the other. 8 out of 10 of the animals which were made thirsty on the test-run chose correctly in spite of an established preference for the other reward. Only 1 out of the 11 animals made hungry chose correctly. Possible explanations of this result are examined.
Apparent Changes in the Visual Threshold as a Function of Subliminal Stimulation: A Preliminary Report
Authors: Dixon N. F.
Published: March 2008

A methodological difficulty in the traditional perceptual defence experiment is that of trying to use verbal reports as a measure of threshold changes. The following experiment handles this difficulty by using the method of closed loop control. The design involves obtaining from the subject a continuous record of his awareness threshold for light entering the left eye while verbal material, dichotomized regarding emotional value, is presented, below threshold to the right eye. The data from this first stage of the research provide some support for the hypothesis that the threshold of awareness will vary as a function of sub-threshold presentations.
Visual Discrimination of Shape by Octopus
Authors: Sutherland N. S.
Published: March 2008

An investigation of the relative discriminability of circles and squares, and circles and triangles for octopus is described. The main findings were: (1) The three pairs of figures, circle and square with base horizontal, circle and square with base at 45° to the horizontal, circle and equilateral triangle were equally discriminable for the octopus. (2) Complete transfer occurred to larger and smaller figures. (3) No transfer occurred from a square in one orientation to a square rotated through 45°, nor did training with the square in one orientation lead to any saving when the discrimination was relearned with the square in the other orientation. (4) No transfer occurred from a square to a pentagon. (5) The method of training with reward on every positive trial leads to quicker initial learning of a discrimination than training with reward only where the positive figure is attacked, but discriminatory performance with the two methods approached the same asymptote. The results are in agreement with findings with other animals where these are available for comparison.
The Lability of the Tactile-Kinaesthetic Framework
Authors: Sandström Carl Ivar
Published: March 2008

This paper is concerned with the ability to recognize settings of a rod (pivoted at the centre) at various angles of tilt without the use of vision. Five angles of tilt, all within the upper right quadrant, were used and 80 subjects took part in the experiments. It is shown that tactile-kinaesthetic recognition of a given angle of tilt is decidedly poor, subjects commonly reporting that the position of the rod had been changed. The direction of these subjective shifts was found to be in general towards the centre of the quadrant. If, following the recognition experiments, the subjects were required to judge settings of the rod in fact vertical and horizontal, errors made tended to be in a direction opposite to that normally found in making these judgements. It was further found that attempts to reinstate the original settings led to mean judgements equivalent to those given on the recognition tests, but with signs reversed. These various phenomena are ascribed to lability and disorganization of the tactile-kinaesthetic framework. An analogy with the autokinetic phenomenon is adduced.
Note on Luminous Flux Discrimination in Monkey and Man
Authors: Gross Charles G. , Weiskrantz Lawrence
Published: March 2008

Subjects were instructed to equate the brightness of two stimuli of different areas presented alternately to the far periphery. The results are closely describable by IA = k (Ricco's Law), indicating that the subjects equated total luminous flux. It is suggested that these results and certain other behavioural and anatomical considerations make it unnecessary to consider flux discrimination a “subcortical” or “lower” visual function as compared with brightness discrimination.
Accuracy of Aiming in Linear Hand-Movements
Authors: Begbie G. H.
Published: March 2008

Six subjects took part in an experiment which consisted of drawing, in a horizontal plane, a number of lines of different lengths and in different directions. The lines were drawn from a starting-point towards a target-point, and the instructions and previous practice were designed to ensure that the lines were drawn in one movement without appreciable amendment during the drawing. The direction and length of the lines were both found to affect the accuracy of aiming, and certain directions showed a persistent bias in the distribution of their errors. Closing the eyes just prior to and during the drawing of the lines had the result of diminishing the effect of changes in direction and length, but it increased the bias. In attempting a theoretical analysis of the results, some of the limitations imposed by human anatomy have been considered in an elementary way. The general conclusion is that, in this task, the effects of altering length, of altering direction and of opening or closing the eyes can, to a great extent, be plausibly ascribed to the particular anatomical nature of the human operator, provided one makes certain simple assumptions about the theory of movement control.