Smaller Neighbors Research Articles

The effect of neighbours on the mortality of harvester ant colonies

1. This study investigates how the density and size of conspecific neighbours affected the mortality of established colonies. Data were from a population of 250–300 colonies of the red harvester ant [Pogonomyrmex barbatus (F. Smith)], on a 10‐ha site, from 1988 to 1995. 2. Colonies are more likely to die as they grow older. 3. Small neighbours tend to lower the probability of dying. 4. The probability of dying varied significantly from year to year. 5. There was little effect of crowding on mortality. 6. There appeared to be no spatial effects, on the scale of 25. m, on the probability of dying. 7. Previous work shows effects of density on the founding of new colonies and on the reproductive output of established ones. The results presented here indicate that competition with neighbours rarely causes the death of established colonies.

Symmetry of Below-Ground Competition between Kochia scoparia Individuals

Competition among individual plants is usually asymmetric, i.e. larger plants are able to obtain a disproportionate share of the resources (for their relative size) and suppress the growth of smaller individuals. There is evidence that the asymmetry of competition is primarily due to shading, but there is very little information about the symmetry of competition below ground. We grew Kochia scoparia individuals singly and in pairs in containers for 54 d with dividers above ground so that competition could occur only below ground. Initial size differences were generated by a 10-d difference in sowing date. There was no evidence that larger individuals had a disproportionate effect on smaller individuals; the effect of a small neighbor on the growth rate of a plant was similar for large and small plants, as was the effect of a large neighbor. The results demonstrate that competition for resources below ground can be symmetric. When competition is symmetric, it will not exacerbate initial size differences.

Regional Powers and Small State Security: India and Sri Lanka, 1977–90. By K. M. de Silva. Washington, D.C.: Woodrow Wilson Center Press, 1995. xvii, 388 pp. $48.50 (cloth).

Regional Powers and Small State Security recounts India's involvement in the affairs of its much smaller neighbour, Sri Lanka, over the question of Tamil separatists in the northern and eastern parts of the island. K. M. de Silva first examines Indian regional ambitions and Indian-Sri Lankan relations during the cold war. He explores the origins of ethnic strife in Sri Lanka and the interests of lndia, with its own large Tamil population, in that strife. He then tells the story of lndia's involvement in three stages. From about 1980, India provided covert support for Sri Lanka's Tamil separatists operating from the southern Indian state of Tamil Nadu. From 1983 to 1987, India attempted to serve as mediator between the separatists and the Sri Lankan government. From 1987 to 1990, India was a combatant against the separatists in Sri Lanka. The author has had special access to confidential Sri Lankan official sources. On the basis of those documents, he further interviewed all politicians and senior officials involved in negotiations on both the Indian and the Sri Lankan side. This book significantly broadens the base of information available for students of South Asia and of ethnic conflict.

Inducible aggression and intraspecific competition for space in a marine bryozoan, Membranipora membranacea

We experimentally investigated the causes and consequences of stolon production in the marine bryozoan Membranipora membranacea. Inducible stolons appear to mediate contests for space among conspecifics by slowing the growth of adjacent competitors. However, because stolons are produced in some but not all competitive interactions, we examined whether environmental factors such as food and hydrodynamic regime regulate their production. Furthermore, because stolons are ephemeral, persisting for only 24 h, we removed stolons to determine whether stolon production affected the outcome of competitive contests. Removing stolons from large colonies reduced their ability to surround a small neighbor, but increased their growth rate. Control colonies, producing their full complement of stolons, grew more slowly than colonies with stolons removed, suggesting that there is a tradeoff between stolon production and growth. The rate of stolon production was higher in colonies grown under lower food conditions. The likelihood that waterborne chemical or hydrodynamic cues induce stolon formation is diminished by our finding that the frequency of stolon production was unaffected by the relative positions of two interacting colonies in unidirectional flow.

Microstructural study of hot pressed HDDR Nd - Fe - B magnets

Systematic microstructural studies of hot pressed HDDR, fully dense magnets have been carried out. A fine grained, hard magnetic phase structure with a grain size of a few hundreds of nanometres is the most outstanding microstructural characteristic of these magnets. Apart from the compact fine grained microstructure with hardly any Nd-rich phase, partially isolated, fine hard magnetic grains with a Nd-rich surrounding were also found. Abnormal grains were observed, arising from the early stages of growth. These grains had a close contact to small neighbouring grains as well as larger abnormal grains of up to with straight borders. Other phases identified were the and intergranular platelets.

Effect of arbuscular mycorrhiza on inter- and intraspecific competition of two grassland species.

We were interested in the role of arbuscular mycorrhiza (AM) in the competition between plants of different sizes. A pot experiment of factorial design was established, in which AM root colonization and competition were used as treatments. Five-week-old Prunella vulgaris seedlings were chosen as target plants (i.e. plants whose response to competition was studied) and the following (13 replicates of each) were used as neighbours: (1) a large, 10-week-old P. vulgaris, (2) two P. vulgaris seedlings, and (3) a large, 10-week-old Fragaria vesca. In the experiment where small neighbours were grown together with small target plants, competition did not reduce target plant weight significantly, compared to the other two treatments. The competitive effects of large neighbours were significant, regardless of species (both older neighbours reduced the weights of target plants similarly), but there was a clear difference between intra- and interspecific competition when plants were mycorrhizal. In intraspecific competition with a large neighbour, the target plant shoot weight was reduced 24% when inoculated with AM. Thus, AM amplified rather than balanced intraspecific competition. In interspecific competition with old F. vesca, the shoot weights of target plants were 22% greater when inoculated with AM than when non-mycorrhizal. The results showed that, for given soil condition, AM might increase species diversity by increasing competitive intraspecific suppression and decreasing the interspecific suppression of small plants by larger neighbours.

Plant size and spatial pattern in a natural population of Myosotis micrantha

Abstract. We examined spatial distributions and plant sizes along a transect through a natural population of a winter annual, Myosotis micrantha. A size hierarchy existed, as indicated by high values of Gini coefficients of inequality for plant mass and correlated measures. Plants with no immediate conspecific neighbors were larger than plants with one or more near neighbors, suggesting that competition from near neighbors depressed plant size. However, there was strong positive spatial autocorrelation in plant size: large plants were associated with large neighbors and small ones with small neighbors. Plant size was also positively correlated with the combined biomass of near neighbors. The population formed a two‐phase mosaic of patches of relatively large plants alternating with patches of smaller plants. The data suggest that individual plants compete with conspecifics, but the effects of competition are symmetrical. The most likely explanations for this spatially structured size hierarchy are variation in plant density, patchy distribution of resources, or a combination of the two.

A comparison of crown asymmetry between Piceaabies and Betulamaximowicziana

Morphological plasticity in terms of asymmetric display of crowns was compared between Piceaabies (L.) Karst. and Betulamaximowicziana Regel. To evaluate crown asymmetry in relation to local environment, a model that predicts crown asymmetry from topography and configuration of neighbors was applied to data derived from a mixed forest in Hokkaido, northern Japan. Betulamaximowicziana had greater crown asymmetry than P. abies in absolute value. However, observed crown asymmetry of both species was determined by local environment to similar degrees. Some other differences were found between the two species. Crowns of P. abies were more influenced by neighbors than topography, while crowns of B. maximowicziana were more influenced by topography than neighbors. Crowns of P. abies were influenced mainly by larger neighbors, while crowns of B. maximowicziana were influenced by large and by relatively small neighbors.

Cytomimetic Organic Chemistry: Early Developments

AbstractThis article describes how chemical and physical stimuli cause a simple system, the giant vesicle, to undergo a variety of “cytomimetic” transformations such as fusion, fission, endocytosis, budding, aggregation, birthing, and foraging. For example, when a giant vesicle, which happens to have a smaller vesicle inside it, is exposed to octyl glucoside, the smaller vesicle can pass through the outer membrane into the external medium (“birthing”). The resulting injury to the membrane of the host vesicle heals immediately. Addition of cholic acid, on the other hand, induces a feeding frenzy in which a vesicle grows rapidly as it consumes its smaller neighbors. After the food is gone, the giant vesicle then self‐destructs (a case of “birth, growth, and death”). Such lifelike morphological changes were obtained by using commercially available chemicals; thus these processes should be assigned to organic chemistry, and not to biology or even biochemistry, and not to biology or even biochemistry. Experimental details (e.g. the preparation and observation of the vesicles) are included in this review in hopes of helping others enter this undeveloped field.

Germany and the European Community: Beyond Hegemony and Containment?

PART 1 SECTORS: 1 German Business and 1992 - Michael Huelshoff 2 West German Labour and Europe 1992 - Andrei Markovits and Alexander Otto. PART II GERMAN HEGEMONY: 3 Germany and European Integration - Towards Economic and Political Dominance? - Simon Bulmer 4 United Europe and Social Democracy - The EC, West Germany and Its Three Small Neighbours - Paulette Kurzer and Christopher Allen. PART III NETWORKS: 5 The European Left and Political Integration - A New Stage in Social Democracy? - Robert Ladrech 6 The Green Project and Transnational Market Integration - Carl Lankowski. PART IV EXTERNAL RELATIONS: 7 Unified Germany, A Single European Economic Space and the Prospects for the Atlantic Economy - James Clyde Sperling.

Real Exchange Rates Within and Between Currency Areas: How Far Away is EMU?

The renewed quest for a European monetary union raises the question: Is Europe ready for a common currency? We compare the conditional variance and the persistence of real exchange rate shocks within the German monetary union and between Germany and eight European countries to assess the viability of a monetary union in Europe. The results suggest a 'Europe of Two Speeds': A core union among Germany, her smaller neighbors and France would be viable today. Further reduction of real exchange rate variability is needed, in contrast, between these countries and Denmark, Italy, and the United Kingdom. Alternatively, monetary union should be postponed until further adjustment has occurred. Such a waiting period would neither require nor benefit much from further tightening of the current EMS. Copyright 1994 by MIT Press.

The UN and the Cambodian Transition

The UN and the Cambodian Transition Julio A. Jeldres (bio) On 23 May 1993, after more than a decade of repression and intimidation, the people of Cambodia put their trust in the secret ballot in an election organized and supervised by the United Nations and guaranteed by international monitors. In so doing, the majority of Cambodians, for the first time in many years, expressed their desire to live in a democratic society and spoke up by themselves instead of being told what to say by their rulers or being spoken for by foreign sponsors. In a massive voter turnout—90 percent nationwide and as high as 97 percent in some provinces—Cambodians gave 45 percent of the vote and 58 seats in the 120-member Constituent Assembly to the United National Front for an Independent, Neutral, Peaceful, and Cooperative Cambodia (FUNCINPEC in its French acronym), a royalist grouping led by Prince Norodom Ranariddh. The incumbent ruling party, Premier Hun Sen's Vietnamese-backed Cambodian People's Party (CPP), came in second with 38 percent and 51 seats. The Buddhist Liberal Democratic Party (BLDP) won 3.8 percent and 10 seats, with the remaining single seat going to a minor party known as Moulinaka. The guerrilla cadres of the Khmer Rouge, meanwhile, remained on the sidelines, neither fielding candidates nor making good on their threats to disrupt the balloting. Few societies have been as badly devastated by war, foreign occupation, and state repression as Cambodia. In the early 1970s, following the military overthrow of Prince Ranariddh's father, Prince [End Page 104] Norodom Sihanouk, massive U.S. bombing related to the Vietnam War wreaked havoc on the country's infrastructure. Then in 1975 came the darkest chapter in Cambodian history as the Khmer Rouge, a small and extremely violent group of French-educated Marxist intellectuals, fought their way into power. Their rule from 1975 to 1978 was the time of the "killing fields," as at least one million Cambodians were murdered in a horrific campaign of bloody purges and forced evacuations of entire cities. In December 1979, Vietnam launched a massive invasion of its smaller neighbor and installed in power an administration comprising Hun Sen and other former Khmer Rouge cadres hand-picked for their loyalty to Hanoi. The Vietnamese invasion caused a realignment of forces in the region. The countries comprising the Association of Southeast Asian Nations (ASEAN), previously worried most about Chinese expansionism in the region, now joined forces with China and the United States to check the imperial designs of heavily armed Vietnam. The members of ASEAN saw the Khmer Rouge as their only buffer against Vietnam, but one that badly needed to be lent some respectability: thus the noncommunist Cambodian resistance was created. In addition to the FUNCINPEC-sponsored National Army of Independent Cambodia, the noncommunist resistance included the Khmer People's National Liberation Front (KPNLF) forces of Son Sann (who also leads the BLDP). The ranks of the resistance swelled with recruits drawn from the hundreds of thousands of refugees who had fled Cambodia for Thailand immediately after the Vietnamese invasion. On 22 June 1982, the two noncommunist groups joined the Khmer Rouge in establishing an uneasy alliance called the Coalition Government of Democratic Kampuchea (CDGK), which received diplomatic and financial support from ASEAN, China, and the United States and swore continuing resistance to Vietnam and its satellite regime in Phnom Penh. The CGDK occupied the Cambodian seat at the UN, retained diplomatic missions (run by Khmer Rouge members) around the world, controlled some territory in western Cambodia near the Thai border, and was successful in preventing international recognition of the Phnom Penh regime, as well as in securing an annual UN General Assembly resolution condemning Vietnam's actions in Cambodia. But relations between the partners of the CDGK were bloody, with Khmer Rouge troops often killing soldiers from both of the two noncommunist fronts. In 1986, after years of bloody stalemate between the Cambodian resistance on one hand and the forces of Vietnam and the Hun Sen regime on the other, the first signs of movement toward a settlement appeared as both sides gave indications that they would be prepared to talk, first through foreign...

Management of land and livestock contaminated with polychlorinated biphenyls.

Investigations were conducted on several small neighbouring beef cattle and sheep farms that were found to be contaminated with polychlorinated biphenyls (PCBs). The residues detected contained about 62% w/w chlorine and soil concentrations ranged from 0.35 to 1.9 mg/kg. Beef cattle and sheep grazing the contaminated land had PCB concentrations in their fat of 0.3 to 1.7 mg/kg and 0.19 to 0.45 mg/kg, respectively. The concentration of PCBs in the caudal fat of cattle was 0.3 to 2 times the concentration of PCBs in the land they were grazing and was positively related to stocking rates. PCBs were present in milk fat from cattle at about the same concentration as in caudal fat, and lactation appeared to contribute to decontamination. Wool grease from sheep contained about 1 to 2 times the concentration of PCBs in subcutaneous fat. Calves of contaminated cows also became contaminated. The half-life for decontamination of PCBs in a group of 8 young female beef cattle was calculated at 13 months. PCBs were detected in pasture samples at concentrations ranging from less than 0.01 mg/kg to 0.12 mg/kg. However, PCBs were not detected in any sample of hay cut from these paddocks. In 4 sheep fed a sole ration of this hay, traces of PCBs were detected in their fat following 89 days of feeding. Grazing livestock for meat production on land contaminated with PCBs is not recommended because livestock readily acquire residues, and PCBs persist in soil and livestock for long periods. Grazing sheep for wool production on land contaminated with PCBs may be an option.

Geomorphic change implied by regolith — Slope relationships on steepland hillslopes, Taranaki, New Zealand

Slope angle and regolith depth were measured along profile lines covering a range of hillslopes in several small neighbouring drainage basins in Taranaki hill country, New Zealand. Slope measurements show a cyclic variation along the length of broadly rectilinear profiles. Variation in slope on the lower portion of profiles adjacent to stream channels indicates that hillslopes have undergone phases of accelerated downcutting and hillslope rejuvenation. A recent phase of increased erosion and hillslope rejuvenation is suggested for hillslopes steeper than 31° by the steep lowerslope and incised stream channel. Hillslope evolution occurs primarily by parallel retreat of steeper swale sites and slope decline during pauses in the rate of downcutting. All slope profiles show a large range in regolith depth. Mean regolith depth of swale sites is highly correlated with mean profile slope angle. Mean regolith depth decreases and the frequency of landslides increase with increasing mean profile slope angle. Microtopographic variation in regolith depth is attributed mainly to vegetation effects, recurrent landsliding, and in-part to bedrock curvature, hillslope position, and slope angle. Shallowing of regolith is caused by recurrent landsliding on steep swale sites, fluvial erosion at the base of steep profiles, and surface erosion on extremely convex spur sites. The very shallow soil on the steep lowerslope portion of profiles suggests a phase of soil removal, consistent with hillslope rejuvenation. Average depth of regolith is least at 97 cm, and variability greatest, on hillslopes with a profile mean exceeding 31°. Erosion rates are greater on these sites where soil is derived predominantly from underlying Tertiary sandstone. This is attributed to a greater frequency of landsliding compared to hillslopes with a profile slope less than 31° where a more regular and deeper average regolith of 153 cm infers a longer period of hillslope stability consistent with the high volcanic ash content of soils. Airfall andesitic volcanic ash, deposited throughout the Holocene, has largely been removed from steeper sites. The work demonstrates the need to interpret the frequency and distribution of landslides in context with natural geomorphic changes in order to assess the effect that landuse changes has on erosion rates.

Tò πλẽθος in a Treaty Concerning the Affairs of Argos, Knossos and Tylissos

Two inscriptions, one (A) found at Tylissos on Crete, the other (B) found at Argos, both dated about 450, concern relations between Argos and the Cretan towns of Knossos and its smaller neighbour, Tylissos. The close relationship between the treaties of fragment A and fragment B – and therefore the interconnection among Argos, Knossos, and Tylissos – seems generally recognized by scholars. The articles of the agreement lay down a diverse and complex set of arrangements among the three parties, but as a whole, the treaty has been interpreted in two ways: (1) the three πóλεις have entered into some sort of federal union; (2) only Argos and Knossos are signatories to the treaty, while Tylissos is a dependency of Argos. The former interpretation has gained wider acceptance than the latter, and if it is correct, just such a federal union would represent a remarkable advance in the development of Greek political institutions. In this paper we shall press a philological point based upon the information we have both from the treaty and from contemporary sources, and in so doing, we shall attempt to show that a federal union is unlikely. We shall then offer our own interpretation of the regulations governing the insular cities with regard to the formation of alliances and the declaration of friends and enemies.

India's Regional Security Doctrine

Close observers of India's foreign relations in the 1980s disagreed about whether New Delhi's policies toward its smaller neighbors in South Asia' were driven by a clear regional security doctrine. The author of one major study of Indian foreign policy under Indira Gandhi found that no Indian version of the Monroe Doctrine has functioned in Southern Asia.2 Another analyst agreed, declaring in his comprehensive examination of Indian security policy:

The “Gulliver effect” and the “optimal divergence” approach to trade policies: The case of nepal

A country could be small in the world economy yet become big in relation to its smaller neighbors, imposing on them its relative price structure and the consequences of its trade policies. We examine here the consequences of such a “Gulliver” effect, looking at the case of Nepal whose economy is closely linked to the economy of India. Since India's protective policies are not optimal for Nepal, we consider the various alternatives for Nepal. The “optimal divergence” is for Nepal to allow the free import of intermediate and capital goods, while, for import-competing industries, it cannot depart from India's trade policy.

Indian Security Perspectives in the 1990s

For the coming decade, it is imperative that a correct estimate be made for India's security considerations in a changing security environment, and an analysis of the responses that India considers appropriate. The underestimation of a threat would mean an inadequate degree of preparedness, which in turn would mean the erosion of national security in the face of an attack as happened in the case of India's 1962 war with China. On the other hand, an exaggerated estimate of a threat would involve a higher defense preparedness, which would mean countermeasures by an opponent leading to a higher threat environment and, again, the erosion of national security. Sometimes, countermeasures undertaken for safeguarding security become counterproductive. This is what has happened with India's global and regional concerns. India's security considerations are not confined to its immediate neighborhood but span a wider area. Measures undertaken by India to cope with its concerns, coupled with the lifting of many financial constraints, led to the modernization of its armed forces. This has, understandably, led to an increase in threat perceptions among India's smaller neighbors and has created a feeling that India is out to become a regionally dominant minisuperpower. To counter this perceived threat, the smaller nations have developed extraregional links and succumbed to arms proliferation. Like a vicious circle, these latter developments have led to measures from the Indian side for further armed development and a larger threat perception for both India and other South Asian countries.

Formation of voids from negative density perturbations

view Abstract Citations (12) References (11) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Formation of Voids from Negative Density Perturbations de Araujo, J. C. N. ; Opher, R. Abstract The formation of voids from negative density perturbations, present in the recombination era, is of appreciable interest, and a number of investigations on the subject have recently been made. These investigations, in general, include only the effect of gravity and neglect nongravitational physical processes (NPP) such as photon drag and photon cooling. In the present investigation we study the effect of NPP in the formation of voids, following the analysis published by de Araujo and Opher in 1988 made for positive density perturbations. Previous investigations made similarity analysis or postulated the magnitude of the initial density perturbation, δ_i_. We obtain the magnitude of δ_i_ using the same mass dependence as previously used for positive perturbations (e.g., de Araujo and Opher). In general we find that the inclusion of NPP act as a drag, impeding the formation of underdense regions and increasing their present density. We study a spectrum of negative perturbations of the form δ_i_ = -(M/M_0_)^-α^(1 + z_rec_)^-1^, where M_0_ is the mass scale, and z_rec_ is the redshift at recombination. We find, for example, for α = 1/2 (corresponding to a white noise spectrum) and M_0_ ~ 10^15^ M_sun_ (corresponding to a galactic cluster) that the inclusion of the NPP increases the final density of the underdense regions ~ 35%-75% for M ~ 10^9^-10^12^ M_sun_. Our calculations produce underdense regions over several megaparsecs. It is of interest to obtain (for a given range of redshifts), for small neighbor distances (< 1^deg^), the distribution of dwarf galaxies of mass ~ 10^9^ M_sun_ ( ~5 optical mag greater than average galaxies). Our results predict the existence of regions <~ 1/10 the average density for regions of mass ~10^9^-10^10^ M_sun_, and the distribution of dwarf galaxies of mass M ~ 10^9^ M_sun_ are sensitive to these underdense regions. Publication: The Astrophysical Journal Pub Date: February 1990 DOI: 10.1086/168405 Bibcode: 1990ApJ...350..502D Keywords: Cosmology; Mass Distribution; Perturbation Theory; Density (Mass/Volume); Galactic Clusters; Galactic Evolution; Astrophysics; COSMOLOGY; GALAXIES: CLUSTERING; GALAXIES: FORMATION full text sources ADS |

Distance-Dependent Competition Measures for Predicting Growth of Individual Trees

Abstract Modified distance-dependent competition indices were developed for predicting tree growth in plantations. These modified indices adjust the growth of an average tree up and down depending on the size of competitors as compared to the subject tree. A neighbor larger than the subject tree--dominant neighbor--places the subject tree at a competitive disadvantage, whereas a smaller neighbor--suppressed competitor--places it at a competitive advantage. Dead neighbors are included as a special kind of suppressed neighbor. Based on this philosophy, new versions and modifications of distance-weighted size ratio and area overlap indices were developed and compared to some previously published indices. Data from a spacing study established in eucalypt plantations in Portugal were used for the empirical aspects of this study. Single correlations with growth, on a spacing X age basis, were generally higher for the modified indices than for their original unmodified counterparts. Modified indices, in conjunction with stand-level variables, also performed well in multiple linear regression equations for predicting growth of individual trees. For. Sci. 35(3):816-831.