bluuebunny/crossref_metadata_2025 huggingface dataset:
Philip Reis, telephone pioneer
Authors: Beyer Robert T.
Published: July 2012

The name of Phillip Reis is widely known and respected in Germany for his early work on the telephone, but he is almost unknown in America. A teacher at the high school level, Reis put together both a mouthpiece and a receiver, and called the combination a telephone, demonstrating its operation on a number of occasions. This was in 1863, 13 years before Bell’s invention. While the U.S. Supreme Court ruled in 1887 that ‘‘to follow Reis is to fail, to follow Bell is to succeed,’’ it must be remembered that Reis died in 1873, and therefore, had no opportunity to rebut the arguments of Bell and his associates. The distinguished Sylvanus Thompson, Professor of Physics at the University of Bristol, wrote of Reis in 1883, ‘‘The inventor of The Telephone (Reis) will be remembered and honoured in the coming if not in the present age.’’ A discussion of Reis’s instrument, including various comments upon it, will be given.
Beam pattern formation and on-/off-axis pressure in the near field through elastic structures
Authors: García-Osuna Fernando , Hixson Elmer L. , Podio Augusto L.
Published: July 2012

Detailed measurements have been done and compared to analytical models of the beam pattern and on-/off-axis pressure in the near-field region of plane circular transducers in order to model the reflection and transmission of ultrasonic waves from and through steel pipes (casing) and plates immersed in oil. It is shown that for broadband and pure tone pulses in the near field, for free field conditions and through a curved or planar layered media, the sidelobes are smaller and the half-power beamwidth is narrower than in the far field. The beamwidth is slightly dispersed (<1 deg) through the casing and plates of similar thickness, being larger through the planar geometry. Off-axis pressure through these elastic structures reveals condensing and dispersing effects (<2 mm) in the curved and planar geometry, respectively. On-axis pressure, however, for λ < structure’s thickness and plane ultrasonic transducers with size a/λ>5, where a is the transducer radius, the reflected and transmitted sound field is the same from and through both structures and behaves as a well-collimated beam in the near-field region. [Work supported by the University of Texas at Austin and the Mexican Petroleum Institute.]
Active underwater acoustic cancellation with pressure sensor and piezocomposite transducer
Authors: Zhang Jinmin , Zhang Woosuk , Varadan Vijay K. , Varadan Vasundara V.
Published: July 2012

Active underwater acoustic cancellation is investigated experimentally in a water-filled pulse tube using a pressure sensor and a piezo-composite actuator. The pressure sensor is made of thin 1-3 piezo-composite disk encapsulated in acoustic transparent rubber and put right in front of the actuator. A 20-dB echo reduction to harmonic incident waves in 5–10 kHz is achieved experimentally by directly phase-shifting the sensor signal and amplifying it to drive the canceling actuator. A robust analog controller is also developed based on the experimentally identified acoustic reflection coefficient of the piezo-composite transducer with steel backing and the transfer function from piezo-composite transducer to the pressure sensor. Issues such as robustness and stability of the analog controller are also discussed.
Band gaps and localization in periodic and random arrays of 2-D isotropic acoustic scatterers
Authors: Hoskinson Emile M. , Ye Zhen
Published: July 2012

A band-structure calculation for a periodic array of scatterers reveals band gaps—bands of frequency outside of which propagation is relatively unhindered, inside of which waves are evanescent and cannot propagate away from their source. In the case of an array of resonant isotropic 2-D acoustic scatterers, a direct, exact, self-consistent technique incorporating all orders of multiple scattering can be used to calculate the scattered field due to a given source. This can be done for the periodic case where the band-structure calculation is relevant: a region of frequencies is found in which the scattered field is localized around the source, and this region coincides with the calculated band gap. The self-consistent technique has the advantage that it can also be used for an arbitrary random distribution of scatterers. Surprisingly, the localization region proves relatively independent of the scatterer distribution. Further investigation reveals that as the frequency is brought within the localization region, the scatter oscillation phases undergo a kind of phase transition into a coherent state which persists within the localization region, also appearing regardless of the scatterer distribution. [Work supported by the National Science Council of the ROC and National Central University.]
Rough surfaces modeling using CTFM sonar
Authors: Zografos Konstantinos , Probert Penny
Published: July 2012

A new statistical model for the scattering of acoustic signals from rough surfaces is presented. It has been developed to support texture measurements from walls and other structural surfaces using air-borne sonar. The rough surface is divided into a number of elementary surfaces, each with random orientation and positioning around the mean for the whole surface. Each elementary surface is modeled using an extension of the Kirchhoff approximation method for a monochromatic wave source [see O. Bozma and R. Kuc, J Acoust. Soc. Am. 89, 2519–2531 (1991)]. Whereas previous work has accounted only for the envelope of the overall energy received at different angles, from a rough surface, the new model accounts for the nonuniformity in the energy pattern. The model is applied to describe the signal received by a KASPA frequency-modulated sensor, a sensor developed originally as a mobility aid for the blind [see L. Kay, Electronic Spatial Sensing for the Blind (Martinus Nijhoff, Boston, 1985), pp. 125–139]. It has been validated with data from different textured surfaces on buildings in Oxford. In the paper we will discuss its use in classifying surfaces to assist navigation and for inspection.
The role of timbre similarity in the binding of musical features
Authors: Hall Michael D. , Wieberg Kimberly , Plonowski James
Published: July 2012

The visual search literature indicates that features are registered separately, and that a feature binding process is required to perceive objects; primary evidence for this process is the occurrence of illusory conjunctions, the perception of incorrect combinations of presented features (e.g., Treisman and Schmidt, 1982). A corresponding auditory process has been established through illusory conjunctions of musical features, though the factors that contribute to auditory illusory conjunctions remain unclear. The role of one potential factor, the perceptual similarity of features, was examined in two experiments with musically trained listeners. In experiment 1, listeners searched pairs of simultaneous, lateralized tones to identify a presented timbre from a target set and its pitch. The perceptual similarity of each target timbre to its nontarget timbre varied across trials. The results were submitted to models of search performance to assess the incidence of illusory conjunctions and feature misperception as a function of timbre similarity and to account for guessing strategies. Experiment 2 directly determined the similarity of the timbres. Perceptual distance was evaluated by submitting the mean ratings of perceived similarity for each pair of timbres to multidimensional scaling analyses. Implications for the nature of auditory feature integration will be discussed.
Perception of audiovisual speech stimuli
Authors: Sams Mikko
Published: July 2012

In face-to-face communication, speech is seen as well as heard. The important role of visual speech becomes evident under noisy conditions. The efficacy of visual speech is also nicely demonstrated by the so-called McGurk effect: when the auditory syllable /aba/ is dubbed on to the video-taped visual articulation of /aga/, most subjects hear a syllable /ada/. Recent neuromagnetic recordings have revealed a specific integration signal generated at or close to the primary auditory cortex. The onset of this signal is 150–250 ms. In a similar vein, fMRl studies have indicated that the primary and/or secondary auditory cortical areas are active during silent lipreading. It was recently demonstrated in our laboratory that the integration is similar when nonwords and real words are used as stimuli, suggesting that the integration is not much influenced by lexical representations and probably occurs at the phonetical-perceptual information processing stage. New data from our laboratory preliminarily suggests that the perception of audiovisual stimuli is influenced by attention. This indicates that the integration is not, at least totally, automatic.
The interface between the perception and production of speech
Authors: Wise Richard , Scott Sophie
Published: July 2012

Four positron emission tomography studies were reanalyzed to identify anatomically separable, functional subsystems associated with speech perception, speech production, hearing complex, nonspeech sounds, and verbal semantic category verbal fluency. The results from a total of 26, right-handed, male volunteers were included. The results indicated two separate caudal (posterior) ‘‘streams’’ of auditory processing. One, directed along the supratemporal cortical plane, responded to both nonspeech and speech sounds, including the sound of the speaker’s own voice. Activity in response to perception merged at the temporo-parietal junction with a region where activity was linked to speech production. In contrast, the left superior temporal sulcus below (ventrolateral to) the caudal supratemporal plane responded only to an external source of verbal stimuli: but, in addition, it was activated by the recall of lists of words during verbal fluency. The results are compatible with a hypothesis that the caudal superior temporal cortex is specialized for the mimicry of sounds, including repetition, the role of the caudal left superior temporal sulcus being to transiently represent verbal sequences, whether heard or internally generated and rehearsed. These processes are central to the perception, rehearsal (both covert and overt), and eventual acquisition of long-term lexical memories of novel words.
Comparison of wide-band matched field processing algorithms
Authors: Hursky Paul , Tiemann Chris O. , Porter Michael B. , Evans Richard B.
Published: July 2012

There are several ways to realize a wide-band MFP process. The data may be processed in the frequency domain, one frequency at a time, and then incoherently or coherently integrated over the band. Alternatively, the data may be processed in the time domain, by matching modeled correlations (e.g., calculated using a ray trace model) with measured correlations. Auto correlations at a single sensor or interelement cross correlations can be used. We compare the frequency-domain and time-domain approaches with respect to array configuration requirements, sensitivity to array element location errors, and sensitivity to environmental mismatch. We demonstrate our findings using simulated and experiment data.
Acoustic tomography for optimizing matched field processing on a tracking range
Authors: Lazauski Colin J. , Cembrola Joan M. , Miller James H.
Published: July 2012

A future Navy passive tracking range will use a real-time matched field processing (MFP) method. As environmental uncertainty affects the performance of matched field processing (MFP) schemes, a need for near real-time 3-D sound speed profile (SSP) estimations exists. The Navy MFP tracking range will be equipped with a tomographic system to obtain these estimates. This will reduce the error risk of MFP by having timely in situ data available. The tracking range considered covers on the order of up to 340 km2 and is located in shallow water with a sloping bottom (200–600 m). Time and space scales of the oceanography can be short in these regions and rapidly degrade the MFP solutions. Obtaining a real-time estimation of the sound speed field using conventional means requires more time and facilities than are available and therefore the use of tomographic methods is proposed. This study shows that the acoustic tomography system designed for the Navy range can achieve an accuracy of better than 1 m/s. Spatial resolution of 4 km in the horizontal and 10 m in the vertical are possible with eight sources and four vertical receiving arrays.
A Gibbs sampling approach to matched-field source localization and deconvolution
Authors: Michalopoulou Zoi-Heleni
Published: July 2012

In narrow-band source localization the source spectrum is typically unknown. Matched-field techniques employ normalization schemes to remove the uncertainty for the unknown amplitude at the source, whereas consideration of phase differences between replicas and true field addresses the unknown phase issue. In this work we implement a matched-field technique that simultaneously estimates source location and source spectrum. The estimation is performed using an efficient Gibbs sampling scheme. Results of the Gibbs sampling estimation approach are compared to those of the linear (Bartlett) processor under several noise levels. The comparison reveals that the simultaneous process of deconvolution and localization has superior performance to that of the linear localization process. Moreover, improvement in localization is obtained without a significant increase in computational requirements. In addition to the improved performance, the proposed method has the advantage of providing more information than conventional matched-field localization, since it also estimates the source spectrum which is often of great interest. [Work supported by ONR.]
Measurements of stage support on a 1/25 scale model of an orchestra platform
Authors: Jeon Jin Yong
Published: July 2012

Stage support values known as ST1 and ST2 were measured in different stage positions both in a 1/25 scale model and a computer model of an actual large concert hall stage. Tests on the scale model were made both with and without model musicians. For the measurement of ST, different distances to the first musician were tried; 2m clear space around the source and receiver looks optimal. The effect of the side wall profile of the stage was investigated; the profile in the actual hall was found to be unhelpful for support. Different positions were also tested for the orchestra on the large stage. The position with greatest acoustic support was found to be at the rear of the stage, not the position close to the front of the stage, which is commonly used.
The effects of cylindrical diffusers on sound diffusion in a rectangular concert hall
Authors: Chiang Weihwa , Wu Hueiping , Shu Yankun
Published: July 2012

Acoustical measurements in a 1:20 scale model were conducted to investigate the influence of a 1/4-cylinder diffuser on sound diffusion in a rectangular concert hall. Diffusion was evaluated regarding temporal and directional distribution of acoustical energy at individual seats as well as energy distribution over all seats. With volume of 19,000 m3 and seating area of 1,200 m2, the size and shape of the hall were determined based on three classical rectangular concert halls. Overall, diffusers around the stage were more effective for the source at the center, front of the stage than the source at the side, rear of the stage. The hall average values of late interaural cross correlation (IACCL3) were reduced by using transversal diffusers on ceiling or longitudinal diffusers on the side walls. Although the influences on the hall average values of echo criteria (EC) and temporal diffusion (TD) were relatively small, diffusers on the rear stage wall were effective in reducing EC values for the seats near the side walls. Strength factor (G) at the seats under the balcony was significantly increased by placing diffusers on the ceiling. On-going research is conducted to evaluate the effects of diffusers in the audience section. [Work supported by the National Science Council of Taiwan.]
Modal response of coupled spaces
Authors: Najolia Dorothy A. , Atchley Anthony A. , Burroughs Courtney B. , Fahnline John
Published: July 2012

To simulate coupled rooms, two rectangular enclosures were built with a common removable partition between them. The frequency response and spatial distribution of the sound fields were measured when the spaces were coupled together. The inner dimensions of the volumes are 43-by-33-by-26 in. and 32-by-25-by-20 in. The walls are constructed from 0.75-in-thick medium density fiber board. Each enclosed space was instrumented with a 2-D microphone array that was moved in the third dimension, so that the sound field was measured over a 3-D grid. The array in the larger enclosure consisted of 70 electret microphones arranged on a 4-by-4-in. grid, while the array in the smaller enclosure consisted of 42 microphones arranged on a 3.5-by-4-in. grid. An externally coupled compression driver located in a corner excited the larger enclosure. The common wall was interchangeable so that location and size of the opening between the enclosures could be studied. A detailed description of the enclosures is presented, as well as representative data showing the utility of the enclosures in investigating the effects different couplings have on the sound fields. [This work is supported in part by the Penn State Applied Research Laboratory and the College of Engineering.]
Comparison of acoustical measurements, calculations, and software for a seminar room
Authors: Christoff Jerry P. , Vital Rebeka
Published: July 2012

The Verle Annis Gallery is a rectangular room with a volume of approximately 20000 ft3. Used primarily for seminars, it is known for its poor acoustic qualities. Various acoustical parameters were measured in the space using MLSSA software. The results were compared to calculations based upon the room geometry and the acoustical properties of the room surfaces. Finally, CATT-Acoustic software was used to model the room in its present condition and also with the addition of acoustical treatment and sound reflecting panels. A novel mechanized device was designed to improve the sound isolation between two simultaneous presentations. A comparison of the measured, calculated, and simulated results are presented. [This work was partially supported by the Paul S. Veneklasen Research Foundation.]
Buried objects detection and classification with a 3-D parametric sonar
Authors: Guyonic Stéphane
Published: July 2012

This paper deals with a new sonar concept suitable for mine detection and classification in shallow and very shallow water. This concept is based on a 3-D high-resolution imaging information obtained from a 2-D scanning. Sediment penetration and narrow-beam constraint is made possible by the use of the parametric technique. A specific tool has been designed to be able to make a connection between a real operational configuration and experimental needs. A 2×2 m2 suspension frame has been built to allow the sonar displacement along the two axis direction. This suspension frame has been deployed first in a pool and then at sea above three different areas where mines and rocks had been buried. Experiments have been conducted in a shallow water area with the suspension frame mounted 2 m above the sea floor made of rough sand. Three-dimensional imaging techniques have been used to process the data and very good results have been obtained. Underwater mine and object detection and shape classification have been successfully demonstrated up to half a meter sediment burial. This paper shows these first results and describes sonar and signal characteristics and then discusses the data and image processing.
Low frequency sound propagation across a land-water boundary
Authors: White Michael J.
Published: July 2012

Sound waves propagating beyond a shoreline experience changes in surface impedance, surface roughness and refraction profile with distance. Measurements of the temperature and wind with tethersonde balloons indicate significantly weaker sound speed gradients over water than over land. At times when over land a temperature inversion was observed, the inversion was always smaller over the water. When the solar heating produced strong upward refraction near the land surface, the temperature profile over water was neutral (lapse). Simulations were run with a parabolic equation model incorporating range dependent boundary refraction profiles and range dependent boundary conditions. The signal levels exhibit changes with distance due to strong refraction over land, but the changes nearly cease in places where the propagation extends over water. Measured spectrum levels from explosion sound propagating across land-water boundaries agree well with the simulations. [Work supported by USACERL, CHPPM and NAVFAC.]
Cross-linguistic perceptual assimilation of American English /r/–/l/ by Korean speakers and Japanese speakers
Authors: Komaki Ryo , Tajima Keiichi , Akahane-Yamada Reiko , Choi Youngon
Published: July 2012

According to the Perceptual Assimilation Model (PAM) [Best et al., JEP:HPP 14, 345–360 (1988)], the difficulties that second-language learners have in distinguishing non-native phoneme contrasts is predictable from the way learners assimilate the non-native sounds into their native phonological system. The present study examined Korean and Japanese adults’ perceptual assimilation of American English (AE) /r/–/l/ contrasts in first two experiments. In experiment 1 (assimilation task), subjects listened to nonsense AE words contrasting /r/ and /l/ in five syllabic positions, and chose one of the native orthographies displayed visually. In experiment 2 (rating task), they listened to the same nonsense words, and rated the ‘‘goodness-of-fit’’ of each stimulus to the presented native orthography on the scale from 1 (least fit) to 7 (best fit). Then, in experiment 3 (identification task), the ability of Korean and Japanese to identify both real AE words and nonsense words was measured, and a significant effect of position was found in both language groups. When the assimilation and rating data from experiments 1 and 2 were interpreted in terms of the PAM categories, the predicted levels of identification accuracy were in good agreement with the identification results in experiment 3.
Perception of English linguadental fricatives by Haitian Kreyol-African American English bilinguals
Authors: Felder Lynda J. , Strange Winifred
Published: July 2012

This study examined Haitian Kreyol/English bilingual speakers’ ability to discriminate non-native fricative and stop contrasts representing substitution patterns in productions of linguadental fricatives in Haitian-accented English and African American English (AAE). Theories of second language (L2) speech learning propose that much of accented speech production in an L2 is due to difficulties in perceiving speech sounds that are not contrastive in L2 learners’ native language or dialect. Neither voiced nor voiceless linguadental fricatives occur in Haitian Kreyol, and Haitian L2 English learners typically substitute /t, d, or v/ for linguadental fricatives. Linguadental fricatives occur in AAE, but vary with context (linguadental, labiodental substitutions or deletions). Haitian/AAE speakers and AAE/standard AE bidialectal speakers were given a categorial discrimination test in which contrasts between linguadental fricatives and alveolar stops or labiodental fricatives in initial, intervocalic, and final position were presented in real words embedded within a short sentence. Preliminary results showed that bilingual Haitian Kreyol/AAE speakers had different patterns of perceptual errors than bidialectal speakers of AAE/SAE. Perceptual error patterns were somewhat related to substitution patterns in Haitian Kreyol and AAE. Further research is underway to investigate age of English learning and dominance of dialect effects on perception. [Work supported by NIDCD-00323.]
Childhood speaking experience and perception of sentences in noise
Authors: Knightly Leah M. , Au Terry K.
Published: July 2012

Perceiving sentences in noise is a challenge for non-native speakers. Does childhood experience with a language help adult learners hear sentences in noise better? Nineteen native Spanish speakers, seven childhood speakers who had spoken Spanish fluently for several years during childhood before becoming predominantly English speaking, 10 overhearers who had overheard Spanish regularly as children but had spoken Spanish minimally, and 27 late learners who had no regular experience with Spanish until high school were asked to repeat aloud 12 Spanish sentences presented in noise (+5 dB S/N level) and then repeat the same sentences presented without noise. Performance on sentences without noise was excellent across groups, with 92%–99% of the words repeated correctly. For sentences in noise, percentages of correctly repeated words differed across groups: 88% (native speakers), 68% (childhood speakers), 49% (overhearers), and 41% (late learners) [F(3,58)=22.417, p<0.001, with sentences-without-noise performance co-varied out]. Native speakers reliably outperformed all other groups; childhood speakers reliably outperformed late learners [by HSD, ps<0.01]; overhearers did not differ reliably from either childhood speakers or late learners. When the test was repeated two months later, childhood speakers performed comparably to native speakers. Results suggest that childhood speaking experience may benefit speech perception when that language is later re-learned in adulthood.
Engaging Students in Molecular Biology via Case-Based Learning
Authors: Bergland Mark , Klyczek Karen , Lin Chi-Cheng , Lundeberg Mary , Tosado-Acevedo Rafael , Toro Arlin , White Dinitra , Wolter Bjorn
Published: July 2012

Case It!, an IBI prize–winning module, provides computer simulations that enable student analysis of biological materials not usually available in laboratories.
The Connectome of a Decision-Making Neural Network
Authors: Jarrell Travis A. , Wang Yi , Bloniarz Adam E. , Brittin Christopher A. , Xu Meng , Thomson J. Nichol , Albertson Donna G. , Hall David H. , Emmons Scott W.
Published: July 2012

The Male Wiring Diagram

The function of the nervous system is thought to represent an emergent property of its network connectivity. However, there are few complete descriptions of all the physical connections between neurons within a real nervous system. Working in nematodes,

Jarrell
et al.

(p.
437
; see the Perspective by

Chklovskii and Bargmann

) identified the complete connectome—every single chemical and gap junction synapse—of the tail ganglia, which govern mating behavior.
Plasmonic Nanolaser Using Epitaxially Grown Silver Film
Authors: Lu Yu-Jung , Kim Jisun , Chen Hung-Ying , Wu Chihhui , Dabidian Nima , Sanders Charlotte E. , Wang Chun-Yuan , Lu Ming-Yen , Li Bo-Hong , Qiu Xianggang , Chang Wen-Hao , Chen Lih-Juann , Shvets Gennady , Shih Chih-Kang , Gwo Shangjr
Published: July 2012

Going Green with Nanophotonics

Plasmons are optically induced collective electronic excitations tightly confined to the surface of a metal, with silver being the metal of choice. The subwavelength confinement offers the opportunity to shrink optoelectronic circuits to the nanometer scale. However, scattering processes within the metal lead to losses.

Lu
et al.

(p.
450
) developed a process to produce atomically smooth layers of silver, epitaxially grown on silicon substrates. A cavity in the silver layer is capped with a SiO insulating layer and an AlGaN nanorod was used to produce a low-threshold emission at green wavelengths.
A Roadmap for the Assembly of Polyhedral Particles
Authors: de Graaf Joost , Manna Liberato
Published: July 2012

How particles pack together as a solid can often be predicted just from their shape and how many neighbors they have in the fluid phase.
By the Skin of Their Teeth
Authors: Pennisi Elizabeth
Published: July 2012

A catfish that lives in an underground stream in a cave in Ecuador

relies on teeth to sense the water flow around it—teeth that stick out all over its body, a sensory neurobiologist reported at the meeting.
Unusual presentation of a spinal epidural abscess
Authors: Noy Mariana Luisa , George Scaria
Published: July 2012

A 59-year-old female patient presented with a 3-day history of abdominal pain and confusion. She had no significant medical history. On admission her Glasgow Coma Scale was 14/15; she was septic and examination revealed right upper quadrant tenderness. She deteriorated quickly, becoming acidotic and hypoxic, and was sedated, intubated and transferred to the intensive care unit.

Blood tests revealed raised inflammatory markers and blood cultures grewStaphylococcus aureus. Initial CT head revealed raised intracranial pressure and she was treated for meningoencephalitis. Repeat CT head 12 days later showed resolving oedema, and a lumbar puncture was attempted. This drew only frank pus and an abscess was suspected. CT spine confirmed a possible paravertebral abscess. Once extubated, MRI spine was possible which confirmed spinal epidural abscesses—1 month postadmission. These were rapidly drained by the neurosurgical team and the patient is currently receiving rehabilitation in a specialist centre.
Unusual presentation of midgut malrotation with incidental nutcracker syndrome in adulthood: case report and literature review
Authors: HitenKumar Panchal N , Shah Dharita , Priyanka Chiripal B
Published: July 2012

Malrotation of the midgut is generally regarded as paediatric pathology with the majority of patients presenting in childhood. The diagnosis is rare in adults, which sometimes results in delayed diagnosis and treatment. We present the case of a 28-year-old woman who presented with vomiting and mild acute pain in the abdomen. CT scan showed abnormal location of the midgut and abnormal relation of the superior mesenteric artery (SMA) and superior mesenteric vein (SMV) and duodenal jejunal flexure, confirming midgut malrotation. Peroperative findings showed the duodenum, small bowel loops located on the right side of the abdomen. The caecum and appendix were located at the midline in the epigastrium with the presence of Ladd's bands. SMA right and anterior to SMV whirled around SMA. Incidentally, the intraoperatively dilated left renal vein was compressed between the SMA and the aorta, which was confirmed retrospectively on CT scan with no symptoms related to the condition.
Ischaemic colitis associated with oral contraceptive and bisacodyl use
Authors: Ajani Shahnaz , Hurt Ryan T , Teeters David A , Bellmore Lawrence R
Published: July 2012

A woman with a history of hip replacement presented 3 days prior to revision of the hip with abdominal pain, diarrhoea and haematochezia. These symptoms began 6 h after she began taking bisacodyl in preparation for her upcoming surgery. She was on low-dose estradiol for hormone replacement therapy (HRT). Subsequent colonoscopy and biopsies were consistent with acute colonic ischaemia (CI). She was treated with intravenous fluids and antibiotics and discharged and told to stop HRT and bisacodyl. Follow-up colonoscopy 1 month after discharge was normal. This case adds to the three other previously reported cases of bisacodyl-associated CI.
Patterns of abdominal injury in 37 387 disaster patients from the Wenchuan earthquake
Authors: Xu Yinglong , Huang Jiwei , Zhou Jixiang , Zeng Yong
Published: July 2012

Objectives

Due to lack of sufficient data it is difficult to understand fully the pattern of abdominal injury after an earthquake. This study aimed to evaluate the pattern of abdominal injury by analysing the data of trauma patients with abdominal injury incurred during the 2008 Wenchuan earthquake.

Methods

We retrospectively reviewed the medical records of 37 387 inpatients. Among them, 883 (2.36%) cases of abdominal injury were deemed eligible and enrolled for analysis. The data analysed included demographics, category of abdominal injury, associated injury type, cause of injury, treatment and clinical outcome, as well as risk factors for death.

Results

Abdominal injury was often accompanied with multiple injuries. Injury of the abdominal wall was the most frequent type of earthquake-related abdominal injury (32%). The spleen was the most commonly injured abdominal organ (18%). Of the 883 patients evaluated, 221 cases received operations and 41 cases died. The highest death rate was found in patients with haemorrhagic shock (28/41, 68.3%) caused by intra-abdominal bleeding.

Conclusions

Abdominal injuries are relatively uncommon in earthquake disasters and often present with associated injuries. A timely and complete diagnosis of both abdominal as well as associated injuries is of primary importance in the treatment of patients with abdominal injuries. Knowledge of different types of abdominal injury, and their relative proportions, prevalence of associated injuries, risk factors and final clinical outcomes observed in this study may be of valuable reference in dealing with major earthquake events in the future.
Tissue oxygen saturation measurement in prehospital trauma patients: a pilot, feasibility study
Authors: Lyon Richard M , Thompson Julian , Lockey David J
Published: July 2012

Background

This study evaluated the feasibility of prehospital tissue oxygen saturation (StO2) in major trauma patients.

Methods

A prospective, pilot feasibility study carried out in a physician based prehospital trauma service.

Results

Prehospital StO2was recorded on 13 patients. Continuous StO2monitoring was achieved on all patients, despite intermittent failure of pulse oximetry and non-invasive blood pressure monitoring in six patients. No adverse outcomes of StO2monitoring were reported. The specific equipment used was reported to be inconveniently bulky and heavy for use in the prehospital setting.

Conclusions

Prehospital measurement and monitoring of StO2is feasible in trauma patients undergoing prehospital anaesthesia and may be useful in the early identification of shock, triggering of transfusion protocols and guiding fluid resuscitation.
A SEQUENCE OF QUANTUM GATES
Authors: HARDY Y. , STEEB W.-H.
Published: July 2012

We study a sequence of quantum gates in finite-dimensional Hilbert spaces given by the normalized eigenvectors of the unitary operators. The corresponding sequence of the Hamilton operators is also given. From the Hamilton operators we construct another hierarchy of quantum gates via the Cayley transform.
Expansion properties of (secure) wireless networks
Authors: Panconesi Alessandro , Radhakrishnan Jaikumar
Published: July 2012

We show that some topologies arising naturally in the context of wireless networking are low-degree, expander graphs.
Centralized and distributed task allocation in multi-robot teams via a stochastic clustering auction
Authors: Zhang Kai , Collins Emmanuel G. , Shi Dongqing
Published: July 2012

This article considers the problem of optimal task allocation for heterogeneous teams, for example, teams of heterogeneous robots or human-robot teams. It is well-known that this problem is NP-hard and hence computationally feasible approaches must develop an approximate solution. Here, we propose a solution via a Stochastic Clustering Auction (SCA) that uses a Markov chain search process along with simulated annealing. This is the first stochastic auction method used in conjunction with global optimization. It is based on stochastic transfer and swap moves between the clusters of tasks assigned to the various robots and considers not only downhill movements, but also uphill movements, which can avoid local minima. A novel feature of this algorithm is that, by tuning the annealing suite and turning the uphill movements on and off, the global team performance after algorithm convergence can slide in the region between the global optimal performance and the performance associated with a random allocation. Extensive numerical experiments are used to evaluate the performance of SCA in terms of costs and computational and communication requirements. For centralized auctioning, the SCA algorithm is compared to fast greedy auction algorithms. Distributed auctioning is then compared with centralized SCA.
An erasure-resilient encoding system for flexible reading and writing in storage networks
Authors: Mense Mario , Schindelhauer Christian
Published: July 2012

We introduce the Read-Write-Coding-System (RWC), a very flexible class of linear block codes that generate efficient and flexible erasure codes for storage networks. In particular, given a message
x
of
k
symbols and a codeword
y
of
n
symbols, an RW code defines additional parameters
k≤ r,w≤ n
that offer enhanced possibilities to adjust the fault-tolerance capability of the code. More precisely, an RWC provides linear
(n,r,d)
-codes that have: (a) minimum (Hamming) distance
d = n-r+1
for any two codewords, and (b) for any codeword
y
1
there exists a codeword
y
2
with distance of at most
w
. Furthermore, depending on the values
r,w
and the code alphabet, different block codes such as parity codes (e.g., RAID 4/5) or Reed-Solomon (RS) codes (if
r = k
and thus,
w = n
) can be generated. In storage networks in which I/O accesses are very costly and redundancy is crucial, this flexibility has considerable advantages as
r
and
w
can optimally be adapted to read or write intensive applications; only
w
symbols must be updated if the message
x
changes completely, which is different from other codes that always need to rewrite
y
completely as
x
changes. In this article, we first state a tight lower bound and basic conditions for all RW codes. Furthermore, we introduce special RW codes in which all mentioned parameters are adjustable even online, that is, RW codes which are adaptive to changing demands. At last, we investigate the question for which choices of
(k,r,w,n)
a coding system exists over the binary alphabet F
2
= {0,1} and discuss how RW codes can be combined.
A shared-secret free security infrastructure for wireless networks
Authors: Sang Lifeng , Arora Anish
Published: July 2012

This article develops a shared-secret free wireless security infrastructure that provides confidentiality, identity authentication, message authentication, integrity, sender nonrepudiation, receiver nonrepudiation, and anonymity. Our infrastructure is based on two physical primitives, namely collaborative jamming and spatial signature enforcement, and a zero knowledge alternative for bootstrapping trust. Notably, it eschews the use of shared secrets, while providing a cryptosystem that is no less secure than conventional cryptosystems.
Control-based p-persistent adaptive communication protocol
Authors: Blanchini Franco , Caneva Daniele De , Montessoro Pier Luca , Pierattoni Davide
Published: July 2012

An enhancement to the CSMA p-persistent protocol family is proposed, based on a fully decentralized control that adjusts the message transmission rate of each node to the estimated density of surrounding transmitting nodes. The system does not require enumeration of nodes nor control messages, the only input to the control coming from the physical medium occupation. In addition to communication protocols, this technique can be used as inexpensive and efficient density estimation of physical entities in highly dynamic scenarios. Stability conditions are proposed by means of a rigorous theoretical investigation. We prove that our algorithm ensures stability even with unknown and time--varying network topologies. We show that good channel exploitation levels can be assured as well by suitably tuning the control parameters. A digital algorithm for practical implementation is proposed. The results are supported by simulation experiments.
Advertising gets personal
Authors: Greengard Samuel
Published: July 2012

Online behavioral advertising and sophisticated data aggregation have changed the face of advertising and put privacy in the crosshairs.
The internet is everywhere, but the payoff is not
Authors: Forman Chris , Goldfarb Avi , Greenstein Shane
Published: July 2012

Examining the uneven patterns of Internet economics.
Continuity and robustness of programs
Authors: Chaudhuri Swarat , Gulwani Sumit , Lublinerman Roberto
Published: July 2012

Computer scientists have long believed that software is different from physical systems in one fundamental way: while the latter have continuous dynamics, the former do not. In this paper, we argue that notions of continuity from mathematical analysis are relevant and interesting even for software. First, we demonstrate that many everyday programs are
continuous
(i.e., arbitrarily small changes to their inputs only cause arbitrarily small changes to their outputs) or
Lipschitz continuous
(i.e., when their inputs change, their outputs change at most proportionally). Second, we give an mostly-automatic framework for verifying that a program is continuous or Lipschitz, showing that traditional, discrete approaches to proving programs correct can be extended to reason about these properties. An immediate application of our analysis is in reasoning about the
robustness
of programs that execute on uncertain inputs. In the longer run, it raises hopes for a toolkit for reasoning about programs that freely combines logical and analytical mathematics.
An initial study of effects of temporary disabilities
Authors: Macík Miroslav , Sporka Adam J. , Slavík Pavel
Published: July 2012

The research of disabilities and their effects on the usability of the user interfaces has long since been established itself in the field of the human-computer interaction. The target groups of this research mostly include people with permanent disabilities (vision-, motor-, or hearing-related). Due to a number of reasons (illness, injury, etc.), a user may enter the state of disability only for a limited amount of time
(temporary disability)
.
Abstracts of recent doctoral dissertations in computer algebra
Authors: Johnson Jeremy
Published: July 2012

Each month we are pleased to present abstracts of recent doctoral dissertations in Computer Algebra and Symbolic Computation. We encourage all recent Ph.D. graduates (and their supervisors), who have defended in the past two years, to submit their abstracts for publication in CCA. Please send abstracts to the CCA editors editors_SIGSAM@acm.org for consideration.
Series crimes
Authors: Stoutemyer David R.
Published: July 2012

Puiseux series are power series in which the exponents can be fractional and/or negative rational numbers. Several computer algebra systems have one or more built-in or loadable functions for computing truncated Puiseux series. Some are generalized to allow coefficients containing functions of the series variable that are dominated by any power of that variable, such as logarithms and nested logarithms of the series variable. Some computer algebra systems also have built-in or loadable functions that compute infinite Puiseux series. Unfortunately, there are some little-known pitfalls in computing Puiseux series. The most serious of these is expansions within branch cuts or at branch points that are incorrect for some directions in the complex plane. For example with each series implementation accessible to you.

Compare the value of (
z
2
+
z
3
)
3/2
with that of its truncated series expansion about
z
= 0, approximated at
z
= ?0.01. Does the series converge to a value that is the negative of the correct value?

Compare the value of ln(
z
2
+
z
3
) with its truncated series expansion about
z
= 0, approximated at
z
= ?0.01 + 0.1i. Does the series converge to a value that is incorrect by 2π
i
?

Compare arctanh(?2 + ln(
z
)
z
) with its truncated series expansion about
z
= 0, approximated at
z
= ?0.01. Does the series converge to a value that is incorrect by about π
i
?

At the time of this writing, most implementations that accommodate such series exhibit such errors. This article describes how to avoid these errors both for manual derivation of series and when implementing series packages.
Erratum: Photopatternable Electrical Conductive Ag- SU-8 Nanocomposite for MEMS/MST
Authors: Khosla Ajit , Gray B.L.
Published: July 2012

On page 313, the complete list of authors should include M. Pallapa, I. G. Foulds, and M. Parameswaran, who are all affiliated with the Institute for Micromachine and Microfabrication Research, Simon Fraser University, Burnaby, BC, V5A1S6.
Biomechanical constraints on the feedforward regulation of endpoint stiffness
Authors: Hu Xiao , Murray Wendy M. , Perreault Eric J.
Published: July 2012

Although many daily tasks tend to destabilize arm posture, it is still possible to have stable interactions with the environment by regulating the multijoint mechanics of the arm in a task-appropriate manner. For postural tasks, this regulation involves the appropriate control of endpoint stiffness, which represents the stiffness of the arm at the hand. Although experimental studies have been used to evaluate endpoint stiffness control, including the orientation of maximal stiffness, the underlying neural strategies remain unknown. Specifically, the relative importance of feedforward and feedback mechanisms has yet to be determined due to the difficulty separately identifying the contributions of these mechanisms in human experiments. This study used a previously validated three-dimensional musculoskeletal model of the arm to quantify the degree to which the orientation of maximal endpoint stiffness could be changed using only steady-state muscle activations, used to represent feedforward motor commands. Our hypothesis was that the feedforward control of endpoint stiffness orientation would be significantly constrained by the biomechanical properties of the musculoskeletal system. Our results supported this hypothesis, demonstrating substantial biomechanical constraints on the ability to regulate endpoint stiffness throughout the workspace. The ability to regulate stiffness orientation was further constrained by additional task requirements, such as the need to support the arm against gravity or exert forces on the environment. Together, these results bound the degree to which slowly varying feedforward motor commands can be used to regulate the orientation of maximum arm stiffness and provide a context for better understanding conditions in which feedback control may be needed.
Self-motion leads to mandatory cue fusion across sensory modalities
Authors: Prsa Mario , Gale Steven , Blanke Olaf
Published: July 2012

When perceiving properties of the world, we effortlessly combine multiple sensory cues into optimal estimates. Estimates derived from the individual cues are generally retained once the multisensory estimate is produced and discarded only if the cues stem from the same sensory modality (i.e., mandatory fusion). Does multisensory integration differ in that respect when the object of perception is one's own body, rather than an external variable? We quantified how humans combine visual and vestibular information for perceiving own-body rotations and specifically tested whether such idiothetic cues are subjected to mandatory fusion. Participants made extensive size comparisons between successive whole body rotations using only visual, only vestibular, and both senses together. Probabilistic descriptions of the subjects' perceptual estimates were compared with a Bayes-optimal integration model. Similarity between model predictions and experimental data echoed a statistically optimal mechanism of multisensory integration. Most importantly, size discrimination data for rotations composed of both stimuli was best accounted for by a model in which only the bimodal estimator is accessible for perceptual judgments as opposed to an independent or additive use of all three estimators (visual, vestibular, and bimodal). Indeed, subjects' thresholds for detecting two multisensory rotations as different from one another were, in pertinent cases, larger than those measured using either single-cue estimate alone. Rotations different in terms of the individual visual and vestibular inputs but quasi-identical in terms of the integrated bimodal estimate became perceptual metamers. This reveals an exceptional case of mandatory fusion of cues stemming from two different sensory modalities.