Long-distance Calls Research Articles

Scanning near-field image of the wave front at the end of a holey fibre

Photograph by Jeremy Frey Glass fibres as thin as a human hair now carry most of our long-distance telephone calls. To squeeze even more information down a fibre, new types have been developed that have holes with nothing but air inside them. The holes act to improve the confinement of the radiation in the fibre, and can also be designed to modify the light wave in a variety of ways. These holey fibres are an example of a photonic crystal, an assembly of …

On the establishment of an access VPN in broadband access networks

Many corporate networks use the Internet as a cost-effective substitute for expensive leased lines and long-distance telephone calls, for allowing their users to have on-demand connectivity into their intranets through ad hoc tunnels, a concept known as access VPN. Establishing an access VPN in a broadband access network is very often a difficult networking challenge that requires several tunnels to be established between the various involved entities. This is especially the case in an open broadband access network where the association between a host and its ISP is not known to the network in advance. This article discusses several schemes for establishing an access VPN in a broadband access network, and explains the need for the various tunnels in each scheme.

Behavioural responses of Diana monkeys to male long-distance calls: changes in ranging, association patterns and activity

Although much is known about the relationship between vigilance, group size and predation risk, behavioural responses to predation risk and their resultant costs are less clear. We investigated the response of Diana monkeys to increased predation risk by looking at behavioural changes associated with male long-distance calls, which are reliably given to certain predators. After male long-distance calls, group spread and nearest-neighbour distance decreased whilst travel and association rates for the group increased. The average height and exposure level of individuals in the group did not change after calls. Individual Diana monkeys changed their behaviour and were more likely to be vigilant or travel and less likely to engage in social or resting behaviours after long-distance calls. In addition, movement rates increased with the number of species the Diana monkeys were associated with. Diana monkey long-distance calls facilitate the joining of groups of other species. Black and white colobus and lesser spot-nosed monkeys were more likely to be in an association following a long-distance call than before. Behavioural responses, such as increased travel or association rates, that reduce foraging efficiency are interpreted as evidence of a non-lethal impact of increased predation risk.

Do male "long-distance calls" function in mate defense? A comparative study of long-distance calls in primates

Long-distance calls produced by males are common among vertebrate species. Several hypotheses have been proposed to explain features of male long-distance calls and their phylogenetic distribution in primates, but the putative functions of male long-distance calls have yet to be tested comprehensively. We used phylogenetic comparative methods to investigate hypotheses for the function of male long-distance calls. We focused on the mate defense hypothesis, which states that male long-distance calls function in intra-sexual competition for mates, but we also examined factors involving resource defense, mate attraction, and habitat. Phylogenetic reconstruction of male long-distance calls in 158 primate species indicates that the presence of male long-distance calls is the ancestral state. The carrying distance of male long-distance calls is correlated with the size of the home range, which is consistent with the role of male long-distance calls in defending mates, attracting mates, and defending resources. However, measures of male intra-sexual competition were not associated with the evolution of male long-distance calls. Evolutionary transitions were only partly correlated with factors related to mate attraction. Instead, the strongest correlates of male long-distance calls were activity period, body mass, home range, habitat and some measures of resource defense. Our results are consistent with long-distance call production as a costly signal, but detailed study within species is required to assess these costs and the functions of long-distance calls in individual cases. Electronic Supplementary Material is available if you access this article at http://dx.doi.org/10.1007/.

Habitat structure and alarm call dialects in Gunnison's prairie dog (Cynomys gunnisoni)

We examined the relationship between habitat structure and alarm call characteristics in six colonies of Gunnison's prairie dogs (Cynomys gunnisoni) near Flagstaff, Arizona, before and after a mid-summer vegetation change. We found significant differences in alarm call characteristics between colonies, confirming the existence of alarm call dialects. Differences in frequency components but not temporal components of calls were associated with differences in habitat structure. Playback experiments revealed that differences in alarm call structure affected acoustic transmission of calls through the local habitat. Thus, we identify habitat structure as one factor that may contribute to alarm call differences between colonies of Gunnison's prairie dogs. Relationships between call characteristics and habitat structure changed over seasons. Playback experiments suggested that this changing relationship could reflect a change in the purpose of the alarm call between early and late summer. Some components of alarm calls seem tailored for attenuation over short distances in the early summer but for long-distance transmission at summer's end. These differences might arise because pups stay close to their natal burrows in the early summer and disperse throughout a colony in late summer. Alternatively, these differences in alarm call transmission between seasons could be caused by the increase in vegetation in the mid-summer. At the end of the summer prairie dogs could be more dependent on long-distance antipredator calls to offset the loss of visibility caused by the increase in vegetation in the late summer. Copyright 2002.

Polynomial-Time Algorithms for Minimum-Time Broadcast in Trees

This paper addresses the minimum-time broadcast problem under several modes of the line model, i.e., when long-distance calls can be placed along paths in the network. It is well known that the minimum-time broadcast problem can be solved in polynomial time under the single-port edge-disjoint paths mode. However, it is equally well known that either relaxing the model to the all-port edge-disjoint paths mode, or constraining the model to the single-port vertex-disjoint paths mode, leads to NP-complete problems; and exact solutions have been derived for specific topologies only (e.g., hypercubes or tori). In this paper we present polynomial-time algorithms for minimum-time broadcast in trees. These algorithms are obtained by application of an original technique called the merging method , which can be applied in a larger context, for instance, to solve the multicast problem or to address the restricted regimen. The merging method requires solving the minimal contention-free matrix problem whose solution presents some interest on its own.

Why Do the Poor and the Less-Educated Pay More for Long-Distance Calls?

The benefits of competition among the long-distance interexchange carriers (IXCs) are not realized equally by all their customers. Despite the declines in rates under the discount plans, we document that basic message toll service (MTS) rates have been rising for several years. We show that poorer and less educated customers pay more than better educated and more affluent customers. We suspect that the reason for this correlation is that they are more apt to pay the MTS rates or other high rates, and we present some preliminary evidence that this tendency explains the correlation that we find. We also present evidence that the payment differences exist even after controlling for usage. These findings are significant because it seems likely to us that these two patterns (rising MTS rates and higher payments by the poor and the less educated) will each be ameliorated by the entry of the regional Bell operating companies (RBOCs) into long-distance markets - a state-by-state regulatory process that was nearly complete as of the beginning of 2004.

A web-based intelligent fault diagnosis system for customer service support

In traditional help desk service centres, service engineers provide a world-wide customer support service through the use of long-distance telephone calls. Such a mode of support is found to be inefficient, ineffective and generally results in high costs, long service cycles, and poor quality of service. With the advent of the Internet technology, it is possible to deliver customer service support over the World Wide Web. This paper describes a Web-based intelligent fault diagnosis system, known as WebService, to support customer service over the Web. In the WebService system, a hybrid case-based reasoning (CBR) and artificial neural network (ANN) approach is adopted as the intelligent technique for machine fault diagnosis. Instead of using traditional CBR technique for indexing, retrieval and adaptation, the hybrid CBR–ANN approach integrates ANN with the CBR cycle to extract knowledge from service records of the customer service database and subsequently recall the appropriate service records using this knowledge during the retrieval phase.

Competition and Price Dispersion in International Long-distance Calling

This paper examines the relationship between changes in telecommunications provider concentration on international long distance routes and changes in prices on those routes. Overall, decreased concentration is associated with significantly lower prices to consumers of long distance services. However, the relationship between concentration and price varies according to the type of long distance plan considered. For the international flagship plans frequently selected by more price-conscious consumers of international long distance, increased competition on a route is associated with lower prices. In contrast, for the basic international plans that are the default selection for consumers who do not subscribe to special plans, increased competition on a route is actually associated with higher prices. Thus, somewhat surprisingly, price dispersion appears to increase as competition increases.

Communication in crested tits and the risk of predation

It is usually assumed that communication between forest birds is costly in terms of predation. However, there is no direct empirical evidence of these costs. I examined whether contact calls of crested tits, Parus cristatus, could attract predators during the nonbreeding season. I compared attack rates on life-like stuffed specimens with and without playbacks of trilled long-range calls and high-pitched, short-range calls. Crested tit models without playbacks were used as controls. Crested tit models with playbacks of long-range contact calls were attacked significantly more often by sparrowhawks,Accipiter nisus , than the models with playbacks of high-pitched sounds and those without playbacks. These results suggest that calling increases the risk of predation for wintering tits and provide support for the assumption that conspicuous long-distance calling is costly in terms of predation. That models with playbacks of high-pitched signals were attacked at lower rates may indicate that predators cannot hear short-range communication calls as well as the long-range calls.

An Economic Analysis of the FCC's Notice of Inquiry on Flat Rate Charges in the Long Distance Industry

On July 20, 1999, the Federal Communications Commission released a Notice of Inquiry (NOI) seeking comment the impact of certain flat-rated charges on single-line residential and business customers who make few, or no, interstate long-distance calls (1). These rated charges are attributable universal service and access charge reform (1) that the Commission implemented in January of 1998. The purpose of this reform, as indicated by the Commission, was to phase in an economically rational common line rate structure . . . and reduce the support burden on high-volume long-distance and business customers (1). Although the Commission lists its primary as being on the consequence of its own policy reforms, it also inquired about the impact on consumers of flat monthly account maintenance fees charged by some interexchange carriers (IXCs) customers with zero or low usage. This Policy Paper shows that if the goals of Access Reform, both specifically and generally, are be accomplished, it is necessary that the pricing structure of access services and long distance rates consist of both fixed monthly fees and usage charges. Such cost causative, two part pricing structures are consistent with both the stated intent of the Commission's Access Order and the general economic principles of efficient pricing. The Commission's intention eliminate the implicit subsidies created by the pre Reform access pricing structure will, by necessity, force some consumers pay more. Specifically, previously subsidized consumers will pay more while previously subsidizing consumers will pay less. This consequence of Access Reform was expected, indeed inevitable, and is no cause for alarm. Any attempt regulate away intended consequences is particularly undesirable. In addition, this Policy Paper provides some evidence on the relationship between usage and income. This evidence indicates that while usage and income are positively correlated, the correlation is weak. Furthermore, low usage (the focus of the NOI) is found be common at all income levels suggesting that the recent changes in the industry are not excessively burdensome households of a particular income level. Thus, Access Reform would appear be fairly innocuous on fairness grounds.

Acoustic variation of pant hoot calls by male chimpanzees: a playback experiment

Pant hoots, a type of long-distance calls of chimpanzees (Pan troglodytes), were played back to two male chimpanzees in a group of seven captive individuals to determine if chimpanzees would modify those vocalizations in response to strange males. Subjects emitted pant hoots with higher rates of delivery, shorter duration of buildup, and lower minimum fundamental frequency of climax when they were presented with pant hoots of strangers than when they produced the calls spontaneously. Considering the direction of acoustical change, we concluded that the rate of delivery, duration of buildup, and minimum frequency of climax might be associated with the underlying emotional states of the callers rather than call matching. Individual difference between two subject males was significant in minimum frequency and duration of climax and in average frequency of call, which appears to reflect differences of the caller's age and social status. These results suggest that different acoustic variables relate to within- and interindividual differences of these vocalizations.

Prices for long-distance voice telephony in Germany

This paper examines the first 16 months of competition in the German market for long-distance voice telephony on the fixed network. It concentrates on price level and price structure. Competition induced by the entry of both network operators and switch-based service providers decreased the price level substantially. Furthermore, after initial attempts to design innovative price structures, most firms gave up differentiation, and instead charged uniform prices for long-distance calls for residential customers. Moreover, the decrease in the price level seems to have induced a shift in the peak-load structure, which raises concern about the regulation of the peak-load structure of interconnection charges.

Are Consumer Survey Results Distorted? Systematic Impact of Behavioral Frequency and Duration on Survey Response Errors

Using a large-scale consumer database created by AT&T, the authors investigate how actual behavioral frequency and duration systematically affect the direction of errors in consumer survey responses. By analyzing errors in consumers' reports on their frequency of using long-distance telephone calls, letters, cards, and visits for personal communication, the authors demonstrate that high-frequency groups underreported their behavioral frequencies, whereas low-frequency groups overreported them. Similarly, the results show that consumers underestimate the duration of lengthy telephone conversations, whereas they overestimate the duration of short ones. Overall, the authors find that people tend to overestimate both frequency and duration. These compressive regressive effects toward the mean and overall upward bias for both frequency and duration estimations result in a distorted view of the market, which will be incorrectly perceived to be more homogeneous and larger than it really is.

An integrated help desk support for customer services over the World Wide Web — a case study

In a traditional help desk environment, service engineers typically provide a worldwide customer base support through the use of long-distance telephone calls. Such a mode of support is inefficient, ineffective and generally results in high costs, long service cycles, and poor quality of service. The rapid growth of the World Wide Web technology, with its widespread acceptance and accessibility, have resulted in the emergence of Web-based help desk systems. Depending on the functionality provided by such systems, most of the associated disadvantages of the traditional help desk environment can be eliminated. This paper describes a Web-based integrated system, the WebHotLine system, that possesses Web-based retrieval, online multilingual translation capability for service records, rule-base reasoning for direct intelligent fault diagnosis by customers or service engineers, different modes of video-conferencing for enhanced customer support and network security for secure data communications.

Evaluating the effects of new telephone tariffs on residential users' demand and welfare. A model for Italy

Under the pressure of a more competitive environment, the tariff regime for telephone services in Italy is undergoing major changes. The general tendency is towards higher access fees, higher prices of local calls and lower prices of long-distance calls. In this paper we develop and estimate a microeconometric model of residential users' demand for telephone services in Italy which is useful to simulate the behavioural and welfare effects of structural changes of the tariff regime.

Looking to a Digital Future

The Australian Broadcasting Corporation is in the midst of significant change as a result of budgetary pressures from the government and the challenge of the oncoming digital age. Lack of funding and dwindling resources have forced the ABC to shut down many of its regional services and to outsource many of its formerly in-house productions. However, there do appear some ways in which the ABC might meet, as the rhetoric goes, "the challenge of the digital era". Traditionally, the role of the ABC has included the provision of comprehensive coverage of, and service for, the whole of Australia, including regions that would be economically unfeasible for commercial operations to penetrate. Recently, however, budgetary cuts have eroded this role substantially, with the axing of state based current affairs and the cessation of Radio Triple J's planned expansion into regional Australia. The Internet has provided a potential, if problematic, stop-gap solution, through the launch of the ABC's online news service. Internet based news solutions have few of the production-end overheads of the television service. There are no expensive studio set ups, no presenters, no cameras, just text that can be quickly keyed into the system and formatted for instantaneous, non-linear delivery. I should note at this point that currently, this "delivery" is in the passive sense of the word: users must search out the content and download it onto their machines. In Internet jargon, this is called "pull" technology. New technologies being developed promise to "push" the content automatically and directly to a user's computer. The ABC's implementation, taking advantage of all these benefits, is text-based, comprehensive, updated constantly, and easy to use. Currently, however, delivery of Internet-based content is tied to the existing phone network, and with most Internet service providers based in state capitals, regional Internet access is hindered by the cost of long-distance calls. The potential exists, nonetheless, for the ABC to achieve truly national coverage by methods that bypass existing structures. The planned shift by Australian TV networks to digital transmission has the potential to enable new possibilities for public broadcasting. A digital infrastructure could allow information and programming to be cheaply produced at the local level, then recompiled centrally and redistributed across the country. The convergence of computer and television will enable a greater variety of content to be sent to the home -- and, possibly, sent back out again in an altered form. Such a transformation of the way we experience television may well alter the concept of public broadcasting beyond recognition, if not render it obsolete. However, these possibilities, although reasonable given projected advances in technology, so far largely remain fantasy due to the debate over regulation between the Federal government and the commercial networks. It remains to be seen whether the ABC will be able to take advantage of the new opportunities. Citation reference for this article MLA style: Nick Caldwell. "Looking to a Digital Future: Thoughts on the New ABC." M/C Journal 1.1 (1998). [your date of access] <http://www.media-culture.org.au/9807/abc.php>. Chicago style: Nick Caldwell, "Looking to a Digital Future: Thoughts on the New ABC," M/C Journal 1, no. 1 (1998), <http://www.nedia-culture.org.au/9807/abc.php> ([your date of access]). APA style: Nick Caldwell. (1998) Looking to a digital future: thoughts on the new ABC. M/C Journal 1(1). <http://www.media-culture.org.au/9807/abc.php> ([your date of access]).

Why I (Used to) Hate to Give Grades

A en I was but a sprig on family tree, growing up in New Hampshire college town where my father, Professor Zimmerman, taught chemistry and chemical engineering, an emblematic cartoon by William Steig appeared in New Yorker. It depicted a downcast youth glancing surreptitiously at a report card held with distaste by a man in a suit looming bulbously from his armchair. caption, isn't good enough for a Zimmerman-yes, that really was name in cartoon-so succinctly expressed family ethos that my parents made dozens of copies. cartoon became their Christmas card that year. When my siblings and I were in college, the B-plus joke, as we had come to call it, would arrive, anonymously, at midterm and final exam times. As grandchildren arrived they, too, were blessed with copies of their own. The B-plus joke has become subject of long-distance phone calls, impromptu seminars at family reunions, and considerable sardonic mirth. That a B-plus was in fact never good enough for a Zimmerman, however, is my lifelong legacy. Its message will be inscribed on my grave. Over years I've filled up a depressing stack of grade books. Their limp, academic-green covers conceal a myriad of cryptic symbols, which in turn embed stories of work and goofing-off, hope and despair, brilliance and just-going-along-for-the-ride. Although I have always-well, usuallylooked forward to reading papers, and can even tolerate reading exams, calculus of giving grades had become, over time, preferable only to doing income tax. Until last year.

Diana monkey long-distance calls: messages for conspecifics and predators

Primate long-distance calls have typically been interpreted as communication signals between conspecific groups (the ‘resource defence hypothesis’), but their potential role as anti-predator alarm calls has received comparably little attention. Male diana monkeys,Cercopithecus diana dianain the Taı̈ forest of Côte d’Ivoire often utter long-distance calls, either spontaneously or in reaction to a variety of stimuli, including predators and non-predators. The present study focuses only on predation contexts and provides evidence for communication to both predators and conspecifics. Males called only in response to predators whose hunting success depends on unprepared prey, that is, leopards and crowned hawk eagles, but not in response to pursuit hunters, such as chimpanzees and humans, which can pursue the caller in the canopy. Calling was regularly combined with approaching the predator. Both observations suggest that male long-distance calls are used to signal detection to the predator (‘perception advertisement hypothesis’). Analysis of male long-distance calls given to leopards and eagles showed that they differed according to a number of acoustic parameters. The two call variants were played to different diana monkey groups; conspecifics responded to them as though the original predator were present. We conclude that, in addition to their function in perception advertisement, diana monkey long-distance calls function as within-group semantic signals that denote different types of predators.

Mrs. Brent

Mrs. Brent* Gayle Pemberton (bio) My sister Carolyn and I found Papa’s flashlight. In the broad, full sun of a late summer Los Angeles morning in 1956 we trained its beam on the side of the white stucco duplex on Fourth Avenue. Then we marched several times around this home, owned by our grandparents—with its red tile roof and carefully manicured lawn—pointing the beam everywhere and anywhere. There was no flash in the light until we moved to the very end of the backyard, where a screened-in playhouse stood. It was a large, lovely space, shaded by a quartet of evergreen trees and shrubs that identified property borderlines. It was cool and dark, with a high ceiling. Carolyn and I had never really learned to make good use of the playhouse, though. It demanded a kind of play that I assign to the 19th century—or to my idea of large, well-to-do English families: an open, unadorned space where the imagination created everything that was necessary for fun. Peter Pan could have appeared to the Lord children in this space; Alice’s looking glass might well have been in its corner. Nana, Papa, and Mother encouraged us to spend our days there, but we had no toys or play things during our summers in California. More to the point, play for my sister and me was always grounded in some kind of reality, and the emptiness of the playhouse was simply too much for us. On this day, we had been cast out of the house seconds after my mother had received a telephone call from my father in Chicago. We knew something was wrong. Long-distance calls were too expensive to make even at night, but we never made them during daylight hours. This call had to be weighty, and the odds were heavily on the side of awful news. We were dispatched so quickly that I have no recollection of even seeing my mother after she put the receiver down. And there was no call for lunch that day, although meals were a formal part of our lives and we always ate three of them on schedule. The flashlight provided no information for our Holmes and Watson probe. The playhouse seemed extra cavernous that day, arrogantly rebuking our labored attempts at play. We were worried and afraid. And we knew we were being protected from something we did not want to be protected from—whatever it was. Carolyn, older than I—and too old for the playhouse—tried her best to keep us both calm despite the pall, despite the eerie brightness of the house and of the day as we looked out from the dark, behind the playhouse screens. Our agitated boredom and concern were finally allayed hours into the afternoon when Nana came out to tell us that Mrs. Brent, my mother’s best friend, had been [End Page 277] killed in an automobile accident. For hours my mother had been inconsolable, and following conventional wisdom, my grandparents deemed it a sight children should not see. They could only shelter us from the knowledge for a short time, however. Any longer would have encouraged our own barely suppressed panic. We learned some details. Mrs. Brent had been thrown from the car; her daughter and husband had been injured, but not gravely. Carolyn and I looked at each other with a mixture of embarrassment and distress. Our search for clues with a flashlight now appeared thoroughly without style, intelligence, or sensitivity. We knew how much our mother had treasured her friend. Carolyn knew Mrs. Brent’s daughter, Sylvia, but not well. We could not imagine losing our mother; what must Sylvia have felt? And much as we had been screened all day from this awful news, we wished we could have protected our mother from it, just as Sylvia, broken and motherless in some Chicago hospital, would have given everything, I’m sure, to save her mother. I was seven. Mrs. Brent was the first person I knew who had died. And I witnessed her last meeting with my mother. Carolyn, Mother, and I were set to leave the next day...