Open Socket Research Articles

Development of a secure video chat based on the WebRTC standard for video conferencing

The article describes the process of developing a secure video chat based on the WebRTC standard for establishing a connection and exchanging information between end users during a video conference. The analysis of a variety of technologies when creating a video chat was performed, theoretical information on the WebRTC standard was studied. As a result of the analytical review, the shortcomings of the WebRTC technology were revealed - disclosure of the private IP address of the system user. Therefore, an application architecture was proposed that solves this problem. Conventionally, the architecture consists of a number of entities - sending a message to the signal and STUN servers to obtain the necessary information for making a video call and a loop that, using an open socket connection, listens, transmits and reproduces audio and media streams between system participants. A software product was also written as part of this work, which allows you to use video chat without the risk of revealing a private IP address. This product was also compared with existing analogues and a number of features were identified. The developed product can be used for online conferences. To organize a broadcast, you only need to create a room and share a link with its participants. The advantage of this development is security because data transmission occurs only over HTTPS, media streams are encrypted (DTLS and SRTP), the technology does not require the installation of plug-ins. In addition, there is no need to install additional software, the service is cross-platform, supported by most browsers.

The non-ferrous metal toolkit of the Petrovka Culture of the South Trans-Urals

The article presents data on the morphological and typological characteristics of the trade tools of the Pet-rovka Culture of the South Trans-Urals and middle Tobol River region, originating from the sites of Chelyabinsk, Kurgan, and Tyumen Regions (77 specimens in total; 126 specimens in total including knives). According to the radiocarbon dating, the chronological period of the Petrovka sites in the Southern Trans-Urals spans the 19th through 18th centuries B.C. The distribution of tools into types was based on the techniques of typological division of the artifacts, taking into account their shape, presence of certain qualitative features, as well as consideration of the geographical and cultural areal of similar articles. The produce of the Southern Trans-Urals center is repre-sented by a diverse set of metal tools and by functioning of large settlements with metallurgical specialization — Kulevchi 3, Ustye 1, and Shibaevo 1. In the typology of the tool complex of the Petrovka Culture of the Southern Trans-Urals and the Middle Pre-Tobol region, common Eurasian types dominate, being genetically associated with the centers of the Middle Bronze Age of the Circumpontian Metallurgical Province — the Late Yamnaya-Poltavkino, Catacomb Culture, and metal-producing centers of the Corded Ware Culture — Volsk-Lbische and Balanovo. A pronounced variety of the morphotypes of the tools, especially knives, is characteristic of the initial stage of ethnogenesis of the cultures of the forest-steppe and steppe zone of Eurasia during the transitional pe-riod from the MBA to the LBA. Common Eurasian types of tools are characteristic of the cultures of the 1st phase of the Eurasian (West Asian) metallurgical province of the forest-steppe and steppe belt from the Don region to the Irtysh region: Abashevo; Sintashta; Early Srubnaya (Pokrovka); Petrovka (Early Alakul). Specific groups of tools inherent in the tribes of the Petrovka Culture were revealed: axes with a massive head; medium-curved sick-les with a prominent handle; socketed spearheads without eyelets and raised ribs along the edge of the socket; forged arrowheads with a through socket; knives with a straight prominent handle — double-edged and single-edged; knives with a forged open socket. In the appearance of some types of tools among the Petrovka population of the Trans-Urals, such as forged socketed tools — chisels, knives, arrows, double-edged knives with a prominent handle, and sickles with a small curvature, the influence of the Abashevo stereotypes of production is discernible. In the meantime, sufficient data have been obtained on the direct imports or on the conjugation of types of the metal tools and weapons of the Sintashta, Petrovka, and Seima-Turbino Cultures in closed complexes.

IRON AGRICULTURAL TOOLS FROM REVNE

Iron agricultural tools from the Revne agglomeration of Slavs of the 8th—10th centuries is analyzed in the paper. The complex is one of the outstanding sites of the Eastern Croats Slavic tribal group in the Ukrainian Carpathian region (fig. 1). During ca. 50 years of stationary and supervisory explorations almost complete set of agricultural tools for primary and secondary tillage and for harvesting has been accumulated.
 The paper provides detailed description of the tools. Comparative analysis of the materials in geographical environment was carried out both in the area of Raiky culture and synchronous and chronologically close cultures and sites. Iron parts of plow-type tools certify a high level of technical equipment for tillage. Asymmetrical heads are inherent in bow ard. This plow-type tool had the head with iron wide-bladed tip posed horizontally to the ground and also knife coulter and mouldboard. Arable tools of this type cutted and turned the soil. Their use indicates the highest level of development of technical capabilities of tillage in the area of Raiky culture and synchronous archaeological cultures (fig. 2—4, 9). Hoes of two types are presented: the socketed items with a vertical open socket and those with a horizontal solid socket. Both types are well-known (the first type is much more common) but functionally there is no difference between them. Their analogies are common in the area of Raiky culture and synchronous surrounding (fig. 5, 6, 9).
 The harvesting process can be considered traditional for the people of Raiky culture. However there are insignificant differences comparing to the aggregate data. Thus, scythes with a curved handle (mainly used for haymaking and possibly for harvesting cereals with a tight ear) have not yet been occurred in Revne. However, such findings are generally much less common than sickles (fig. 7—9).
 The complex of iron agricultural tools shows the highest level of development of agriculture in the people of Raiky culture. Comparative analysis with other cultural and ethnic groups of the late 1st millennium AD in Central and Eastern Europe also shows that the level of agriculture is close to the achievements of the Saltiv culture.

The application of 3D printed resorbable polymer membranes in extraction sockets and implant sites

Background Hard tissue augmentation prior to and during dental implantation is one of the greatest areas of potential development. Graft materials and barrier membranes are widely utilised but offer relatively little structural support to the augmented tissue during the healing period. A directly 3D printed bioresorbable membrane has the potential to incorporate structural and design features offering support to the graft during bone formation while maintaining barrier properties. Aim/Hypothesis The aims of this study were to assess the feasibility and hard and soft tissue response of the placement of chair side produced sterile, resorbable polymer barrier membranes in extraction sites and buccal wall defects of dental implant sites. Materials and Methods Ten patients were selected with a mean range of 67 years for each of two groups. Group A required socket augmentation following extraction and the other group (B) buccal augmentation to repair a dehiscence or fenestration at the time of implant placement. Teeth were extracted and scanned as STL files (3-shape). The files were then used to design (Fusion 360 + AutoCAD) a rigid resorbable polymer graft (Polyoss R+ Ossform Pty. Australia). This was printed using a Graftmaker FDM 3D printer (Ossform Pty. Australia) as a sterile device at the chair side and fitted at the time of extraction implantation. Biooss (Geistlich AB, Switzerland) was used to fill any significant voids beneath the grafts. Characteristics of Inflammation+ Contour, Stiffness and Closure were ranked non-parametrically by the surgeon on a scale of 0-5 for each parameter at the time of surgery, 2,4,6 and 12 weeks after. Contour was further evaluated by scanning alginate impressions of each graft at placement and 12 weeks Results The parameters of Inflammation, Contour, Stiffness, Stability and Closure were ranked for each group (A - Socket augmentation, B- Implant placement) at 0, 2,4,6 and 12 weeks. The mean and median values for each parameter were tabulated. Mean values were rounded up or down as appropriate. The mean values for inflammation were (0 = no inflammation - 5 frank inflammation with crusting, breakdown and exudate) 0 for Groups A and B at all time intervals. Median values were 0 for both groups. Graft contour (0 for complete lack of contour - 5 as original anatomy) had a mean value of 3 for Group A and 4 for B.Graft stiffness (0 = no support just as an unsupported membrane - 5 sound bone) had mean values of 4 at all intervals for both groups. Stability (0 = moveable, slidable graft - 5 rigid, immobile graft) had mean values of 4 for Group A and 3 for Group B. Wound closure (0 for open socket - 5 is complete closure no exposure of membrane) had a mean value of 2 for Group A and 4 for Group B. Conclusion and Clinical Implications This preliminary clinical study demonstrates that a rigid resorbable polymer graft can be designed and fabricated at the chair side. It can be successfully placed at surgery with no evidence of inflammation. The graft offers benefits in terms of stiffness and support for the early bone formation whilst retaining the features of a barrier membrane. Further studies will provide a means of comparison with established technologies.

Extraction socket sealing using palatal gingival grafts and resorbable collagen membranes

BackgroundSocket sealing surgery is performed for the preservation of the form and volume of the soft tissue by covering the resulting socket with autogenous soft tissue graft or membrane barriers. This procedure is usually necessary to improve the esthetic results of the maxillary anterior or premolar areas.MethodsThis study retrospectively investigated cases involving the open membrane technique or socket sealing surgery with a palatal gingival graft or collagen membrane where implant placement and bone grafting were performed immediately after tooth extraction. From January 2005 to December 2008, socket sealing surgery was performed in 24 patients, and 25 implants were placed.ResultsAll implants were successful in the follow-up period. In the palatal gingival graft group, the mean marginal bone loss was 1.17 mm during the mean follow-up period of 81.0 months. In the collagen membrane group, the mean marginal bone loss was 1.23 mm during the mean follow-up period of 76.9 months. There was no significant difference between the two groups.ConclusionsConsequently, socket sealing surgery is effective at minimizing the loss of soft tissue and alveolar bone.

HTTPAS: active authentication against HTTPS man‐in‐the‐middle attacks

Hypertext transfer protocol secure (HTTPS) relies on a group of pre-trusted certificate authorities (CAs) for authentication and hence can avoid man-in-the-middle attacks. However unfortunately, this authentication architecture can be completely subverted in case any one (usually the weakest one) of CAs has been compromised. To tackle this critical flaw, pioneer works such as notary-based systems and pre-shared secrets have been proposed. These state-of-the-art techniques can neither seek maximal protection from available CAs nor resist potential man-in-the-middle variants. In this study, the authors propose HTTPAS, a new HTTP Active Secure framework that can enhance the HTTPS authentication against man-in-the-middle attacks by actively utilising available CAs and exploiting Internet path diversity as much as possible. In particular, HTTPAS is designed with four practical solutions, each of which can make a unique trade-off among authentication capability, deployment difficulty and efficiency. They have implemented HTTPAS using the open secure sockets layer (SSL) suite, and also evaluated the implementation through experiments on several public certificate data sets and the Internet. Their results have successfully confirmed the authentication effectiveness of HTTPAS with only a few performance overheads and moderate deployment effort.

Safety and absorption characterization of a novel dental collagen wound dressing

Event Abstract Back to Event Safety and absorption characterization of a novel dental collagen wound dressing Monsour Al-Rajhi1, Harold Aberman2 and Gregory Pomrink1 1 NovaBone Products, Research and Development, United States 2 Purdue University, Veterinary Clinical Sciences, United States Purpose: The study evaluated and compared the local reaction and material absorption characteristics of NovaBone Dental Collagen Wound Dressing with a predicate dental collagen wound dressing, ACE Resorbable Collagen Plug (RCP) upon implantation into an open socket extraction site of minipigs. Necropsy was performed 2, 4, or 8 weeks after initial implantation. Methods: Twelve minipigs underwent bilateral surgery to remove the second and third premolars on the right and left mandible. Empty sockets on the animals’ left side received the ACE-RCP (control article) and those on the contralateral side received the NovaBone Dental Collagen Wound Dressing (test article). Figure 1 maps out the implantation sites. Animals were randomized and assigned to three groups consisting of four animals per group. Animals assigned to Group 1 were sacrificed 14 days post-surgery, those in Group 2 were sacrificed 27 or 29 post-surgery (2 animals/day), and those assigned to Group 3 were sacrificed 56 days post-surgery. Local reactivity and material absorption (defined as the physical disappearance of the implanted material from the implantation site) were evaluated via histologic methods at each sacrifice interval. Lighted microscopic evaluations were performed consisting of semi-quantitative evaluation of paired sections for tissue and inflammatory reactions and residual collagen implant absorption. Results: All animals survived to scheduled termination. Overall, animals gained weight throughout the course of the study. There were no adverse changes in appearance, behavior, or activity in animals that were attributed to either the test or control articles. No gross observations attributed to the test or control articles were noted at necropsy (Figure 2). Neither the control nor test implant sites contained recognizable implant material. The predominant implant site findings were fibrosis and osteoneogenesis, which were present in all implant sites at all sacrifice intervals. Adipose tissue infiltrates in implant sites was also similar in the control and test article sites at all sacrifice intervals. This finding was least frequent 14 days post-surgery but had increased 27-29 days post-surgery at which time it plateaued. Cellular infiltrates were most frequent 14 days post-surgery and progressively decreased at subsequent sacrifice intervals. All of these observations were expected responses to the extraction and implant procedure and none were considered to be adverse. The severity scores are summarized in Figure 3. Conclusions: None of the implant sites contained recognizable implant material suggesting that both test and control articles were completely resorbed within 14 days of implantation. Cellular infiltrates were most frequent 14 days post-surgery and progressively decreased at each subsequent sacrifice interval. All of these observations were expected responses to the extraction and implant procedure and none were considered to be adverse. The mean implant site scores for the control and test articles were similar at each sacrifice interval and decreased between day 14 and day 56 post-surgery. Based on the similarity and frequency of the histologic findings and the mean group implant site scores, NovaBone Dental Collagen Wound Dressing and the predicate ACE-RCP perform similarly in vivo. Dr. Dawn Ruben, D.V.M.; Hans Peter Dyke, J.D.; Dr. Melinda Tyner, Ph.D.

Evaluation of hemosponge in promoting dental socket healing after 3rd mandibular premolar extraction in a feline model

Aim: To investigate the healing process following use of collagen sponges in the dental socket after extraction. Wound complications during the study were also evaluated. Methods: 32 cats were included in this study. IV administration of the combination of diazepam (0.22 mg/kg) and ketamine (10 mg/kg) was used to induce general anesthesia. Surgical extraction of both 3rd mandibular premolars was performed. The open dental sockets were divided in two groups. In Group A, the open dental socket on the left side was closed using 4-0 Monocryl in simple interrupted pattern. In Group B, the right dental socket was filled with lyophilized hydrolyzed collagen and the buccal and lingual flaps were sutured using 4-0 Monocryl and simple interrupted pattern. Meloxicam (0.2 mg/kg) was used to manage the post-extraction pain in all cats. Ampicilline 20 mg/kg was used as prophylaxis. The wounds were observed during the study to evaluate any signs of inflammation or dehiscence. Radiographs were taken to compare healing of the socket 3 weeks after the procedure. A 1 mm biopsy punch sample was taken from sockets in all cats for comparison of the healing in both groups. Results: Hemorrhage occurred only in the sockets of Group A. Remission of radiolucent area occurred in both groups. Mean score of inflammation was lower and mean scores of fibrotic reaction and fibroplasia were higher in Group B (p<0.05). Conclusions: Use of hemosponge in alveolar socket may accelerate fibroplasia and formation of the connective tissue and reduce inflammation after tooth extraction. Therefore, post-extraction use of the hemostatic agent in the dental socket is recommended.

Application of Contactless Testing to PCBs with BGAs and Open Sockets

This paper introduces a practical test method that combines statistics with a contactless test approach. Experiments using real PCBs show the effectiveness of the method, where significant z-scores are obtained to discriminate defective interconnects. The studied test cases involve conventional Printed Circuit Boards (PCBs) with Ball Grid Array (BGA) packages and open sockets.

An optimization of the ALICE XRootD storage cluster at the Tier-2 site in Czech Republic

ALICE, as well as the other experiments at the CERN LHC, has been building a distributed data management infrastructure since 2002. Experience gained during years of operations with different types of storage managers deployed over this infrastructure has shown, that the most adequate storage solution for ALICE is the native XRootD manager developed within a CERN - SLAC collaboration. The XRootD storage clusters exhibit higher stability and availability in comparison with other storage solutions and demonstrate a number of other advantages, like support of high speed WAN data access or no need for maintaining complex databases. Two of the operational characteristics of XRootD data servers are a relatively high number of open sockets and a high Unix load. In this article, we would like to describe our experience with the tuning/optimization of machines hosting the XRootD servers, which are part of the ALICE storage cluster at the Tier-2 WLCG site in Prague, Czech Republic. The optimization procedure, in addition to boosting the read/write performance of the servers, also resulted in a reduction of the Unix load.

Reflection Phase Shift for PWB and PCBA Production Testing

Testing of printed wiring boards (PWBs) and printed circuit board assemblies (PCBAs) is part of electronics production that has a great impact on profitability. High throughput and low cost testing is always needed for high quality and reliability. Bare board testing, that is, testing before loading components, is crucial, and can detect such defects as opens, bridges, near-opens, near-bridges, and characteristic impedance mismatches due to process variations and compounding raw material tolerances. If not detected at the bare board stage, the cost of defects can increase 10-fold. Another motivation for an unpopulated board test is that loading expensive components on a set of defective boards could be economically catastrophic. Flying probe systems, which were developed in late 1980s, are commonly used and favorable to perform bare board isolation and continuity testing, especially when the volume is not great enough to justify bed-of-nails purchase. Flying probe system performance for a given bare board depends on the test algorithm, the mechanical speed, and the number of probes. To reduce the cost on expensive test probes and probe maintenance and to accelerate the test time, this paper presents a new and cost-efficient approach to testing both populated and unpopulated boards with open sockets, using a single probe. Specifically, a coaxial probe injects one frequency signal into the PWB trace, and the phase shift between the reflected signal from the trace and the incident wave is detected and compared with the nominal value. This nominal value is determined by testing a defect-free board that already passed direct continuity and isolation testing. By applying this test solution to bed-of-nails equipment, we reduce the amount of probes by 50%. By employing this solution to flying probe systems with two probes, for a given design with NI isolated traces and NA adjacent pairs, we reduce the number of tests from (NI + NA) tests to NI tests as isolation and continuity are performed in one go. Flying probe systems involve mechanical movements that dominate the test time. By reducing the number of mechanical movements, we will dramatically increase test throughput. The experiments demonstrate feasibility for practical use in automatic test equipment (ATE) for PWB and PCBA testing. At the highest sensitivity of the phase shift detector, the prototyped tester is capable of distinguishing between a defective and error-free board with significant margins in case of defects such as opens, DC and RF bridges, and exceeded and different width lines. The margin in the measurement between a defective and a correct board, which depends on the type of the defect, is about 7% to 68%. In the case of loaded board testing, the approach is capable of detecting opens with important margins (our test cases showed 40% and 33%), which makes it a strong candidate approach to be applied officially to PCBA testing where probing is feasible. The approach can be applied to the complete layout or to boost the test strategy where the applied test solutions do not cover 100% of the possible defects.

Single Probe for Bare Board Continuity and Isolation Testing

Bare board testing is vital before components loading. Defects after the PCB manufacturing process are possible such as opens, bridges, near-opens, near-bridges and characteristic impedance mismatches due to process variations and compounding raw material tolerances. Moreover, defects might cost about ten times more when detected in the next test phase, another motivation for unpopulated board test is loading expensive components on a set of defective boards might be economically catastrophic. Flying probe systems, which were developed in late 1980’s are commonly used and favorable to perform bare board isolation and continuity testing, especially when the volume is not big enough to justify bed of nails purchase. Flying probe system performance for a given bare board depends on the test algorithm, the mechanical speed and the number of probes. To reduce the cost on expensive test probes and probe maintenance and to accelerate the test time, this paper presents a new and cost efficient approach to test unpopulated and populated board with open sockets, using a single probe. Specifically, a coaxial probe injects one frequency signal into the PCB trace, the phase shift between the reected signal from the trace and the incident wave is detected and compared with the nominal value, which has been captured from a defect free board, which already underwent direct continuity and isolation testing. The conducted experiments have shown a good feasibility for practical use in the ATE (Automatic Test Equipment) for bare board and loaded board with open sockets. At the highest sensitivity of the phase shift detector, the prototyped tester is capable to distinguish between a defective and error free board with significant margins in case of defects such as opens, DC and RF bridges, exceeded and different width lines. The margin in the measurement between a defective and a correct board, which depends on the type of the defect is about 8 % to 65 %.

Reducing Processor Usage on Heavily-Loaded Network Servers with POSIX Real-Time Scheduling Control

Polling I/O mechanisms on the Unix platform such as select( ) and poll( ) cause high processing overhead when they are used in a heavily-loaded network server with many concurrent open sockets. Large waste of processing power incurs not only service degradation but also various troubles such as high electronic power consumption and worsened MTBF of server hosts. It is thus a serious issue especially in large-scale service providers such as an Internet data center (iDC) where a great number of heavily-loaded network servers are operated. As a solution of this problem, we propose a technique of fine-grained control on the invocation intervals of the polling I/O function. The uniqueness of this study is the utilization of POSIX real-time scheduling to enable the fine-grained execution control. Although earlier solutions such as an explicit event delivery mechanism also addressed the problem, they require major modification in the OS kernel and transition from the traditional polling I/O model to the new explicit event-notification model. On the other hand, our technique can be implemented with low cost because it just inserts a few small blocks of codes into the server program and does not require any modification in the OS kernel.

Secure UNIX socket-based controlling system for high-throughput protein crystallography experiments.

A control system for high-throughput protein crystallography experiments has been developed based on a multilevel secure (SSL v2/v3) UNIX socket under the Linux operating system. Main features of protein crystallography experiments (purification, crystallization, loop preparation, data collecting, data processing) are dealt with by the software. All information necessary to perform protein crystallography experiments is stored (except raw X-ray data, that are stored in Network File Server) in a relational database (MySQL). The system consists of several servers and clients. TCP/IP secure UNIX sockets with four predefined behaviors [(a) listening to a request followed by a reply, (b) sending a request and waiting for a reply, (c) listening to a broadcast message, and (d) sending a broadcast message] support communications between all servers and clients allowing one to control experiments, view data, edit experimental conditions and perform data processing remotely. The usage of the interface software is well suited for developing well organized control software with a hierarchical structure of different software units (Gaponov et al., 1998), which will pass and receive different types of information. All communication is divided into two parts: low and top levels. Large and complicated control tasks are split into several smaller ones, which can be processed by control clients independently. For communicating with experimental equipment (beamline optical elements, robots, and specialized experimental equipment etc.), the STARS server, developed at the Photon Factory, is used (Kosuge et al., 2002). The STARS server allows any application with an open socket to be connected with any other clients that control experimental equipment. Majority of the source code is written in C/C++. GUI modules of the system were built mainly using Glade user interface builder for GTK+ and Gnome under Red Hat Linux 7.1 operating system.

An open socket technique for through-knee amputations in relation to skin problems of the stump: an explorative study

Objective: To compare the conventional socket for through-knee amputees with an open socket system for skin problems and other relevant items. Design: All data were collected during three visits to the prosthetic clinic. At the second visit the conventional socket was replaced by the open socket. The use of both socket types was evaluated with a questionnaire and stump inspection. Setting: The subjects were evaluated at the Rehabilitation Centre, St Maartenskliniek, Nijmegen, the Netherlands. Subjects: Twenty subjects with a unilateral through-knee amputation were included and 13 subjects had a trial with the open socket. Results: There is a significant decrease of hyperhydrosis when wearing the open socket, there is no significant decrease in skin irritation or ulcers. The open socket also gives more comfort in sitting position. Conclusion: A further trial is needed in a selected group of prosthesis users among through-knee amputees to establish the long-term acceptance and benefits of the prosthesis with an open socket.

An open socket technique for through-knee amputations in relation to skin problems of the stump: an explorative study.

To compare the conventional socket for through-knee amputees with an open socket system for skin problems and other relevant items. All data were collected during three visits to the prosthetic clinic. At the second visit the conventional socket was replaced by the open socket. The use of both socket types was evaluated with a questionnaire and stump inspection. The subjects were evaluated at the Rehabilitation Centre, St Maartenskliniek, Nijmegen, the Netherlands. Twenty subjects with a unilateral through-knee amputation were included and 13 subjects had a trial with the open socket. There is a significant decrease of hyperhydrosis when wearing the open socket, there is no significant decrease in skin irritation or ulcers. The open socket also gives more comfort in sitting position. A further trial is needed in a selected group of prosthesis users among through-knee amputees to establish the long-term acceptance and benefits of the prosthesis with an open socket.

Radiographic Reconstruction of Root Morphology in Skeletonized Remains: A Case Study

This is a case study in the application of a laboratory technique first described by Dr. Brion C. Smith in the Journal of Forensic Sciences in January 1992. Our study evaluated a human skull that showed perimortem and/or postmortem tooth loss. It was discovered in 1991 and deemed to have no usable dental information due to severe alveolar bone destruction. In 1994, using minor modifications of Dr. Smith's technique, we sealed off the open tooth sockets and injected a radiopaque material which, after radiographic analysis, revealed previously unobserved dental information. This report demonstrates that root morphology can be reconstructed. This yields radiographic information that may be useful in the identification of unknown human remains.

EFFECT OF OPEN SOCKET ON CABLE TENSION ESTIMATED BY VIBRATION METHOD

The method of estimating tension of bridge cables by measuring their natural frequency, so-called vibration method, is convenient on construction site of structures with cables, Concerning the method some papers have been reported hitherto. In these reports cables are assumed to be clamped on both ends. However, for the estimated tension of cable supported by open sockets, vibration of the sockets has a notable effect, which has not been investigated. In order to get reliable and accurate estimation for tension of cables with open socket, some experimental works were performed and reported in this paper.

Simple and easy method for measurement of ambulatory activity in mice (author's transl)

A hand-made apparatus which is easily manipulative, cheap, durable and clean was used to measure ambulatory activity of a mouse. The apparatus was assembled with the same type of two plastic round basins commercially available (25 cm in diameter) put one upon another. A pivot was fixed at the center of the outsurface of the inner basin (A), and its open end was inserted into the open socket fixed at the center on the bottom of the outer basin (B). Three microswitches equipped on the brim of (B) at equal intervals were activated and the counts were recorded according to the tiltings of (A) through the movements of the mouse. In order to examine accuracy of the measurement, effects of d-amphetamine (1.25 approximately 5.0 mg/kg), methamphetamine (1.0 approximately 4.0 mg/kg), cocaine (10 approximately 40 mg/kg) and morphine (5.0 approximately 20.0 mg/kg) on the ambulatory activity were investigated. Marked accelerating effects were observed dose dependently after the administrations of all the drugs. Furthermore, the patterns of the activity showed characteristic properties of each drug. This method is especially useful to measure the acute effect of drugs on the ambulatory activity in mice, and many units can be set up at the same time.

Acrylic resin root implants: A preliminary report

An investigation was developed to test the clinical possibilities of a method to preserve the residual alveolar bone immediately following tooth extractions. Clinical observations of bone stability over retained roots or teeth led to this study. Observations showed that resorption proceeds at a slower rate over the implant area and that the presence of the implant did minimize the amount of bone loss over the period observed. The nagging fear of the development of malignancy through the use of acrylic resins has caused the temporary withdrawal of an otherwise handy and practical material from future phases of this investigation. It is hoped similarly based investigations using roots of the extracted teeth themselves as implants will be continued. Primary union of the oral tissue over the open socket is an important factor for success. The positioning of the implants (3 mm. or more below the infraalveolar bone crest) appears as a factor in the success of the implant and the organization of the blood clot. Future investigations must bear these important features in mind.