Investigating viscous damping using a webcam

We describe an experiment involving a mass oscillating in a viscous fluid and analyze viscous damping of harmonic motion. The mechanical oscillator is tracked using a simple webcam and an image processing algorithm records the position of the geometrical center as a function of time. Interesting information can be extracted from the displacement-time graphs, in particular for the underdamped case. For example, we use these oscillations to determine the viscosity of the fluid. Our mean value of 1.08 \pm 0.07 mPa s for distilled water is in good agreement with the accepted value at 20\circC. This experiment has been successfully employed in the freshman lab setting.Comment: 13 pages, 5 figure

Design of microprocessor-based hardware for number theoretic transform implementation

Number Theoretic Transforms (NTTs) are defined in a finite ring of integers Z (_M), where M is the modulus. All the arithmetic operations are carried out modulo M. NTTs are similar in structure to DFTs, hence fast FFT type algorithms may be used to compute NTTs efficiently. A major advantage of the NTT is that it can be used to compute error free convolutions, unlike the FFT it is not subject to round off and truncation errors. In 1976 Winograd proposed a set of short length DFT algorithms using a fewer number of multiplications and approximately the same number of additions as the Cooley-Tukey FFT algorithm. This saving is accomplished at the expense of increased algorithm complexity. These short length DFT algorithms may be combined to perform longer transforms. The Winograd Fourier Transform Algorithm (WFTA) was implemented on a TMS9900 microprocessor to compute NTTs. Since multiplication conducted modulo M is very time consuming a special purpose external hardware modular multiplier was designed, constructed and interfaced with the TMS9900 microprocessor. This external hardware modular multiplier allowed an improvement in the transform execution time. Computation time may further be reduced by employing several microprocessors. Taking advantage of the inherent parallelism of the WFTA, a dedicated parallel microprocessor system was designed and constructed to implement a 15-point WFTA in parallel. Benchmark programs were written to choose a suitable microprocessor for the parallel microprocessor system. A master or a host microprocessor is used to control the parallel microprocessor system and provides an interface to the outside world. An analogue to digital (A/D) and a digital to analogue (D/A) converter allows real time digital signal processing

Attraction of mononchoides longicaudatus and M. fortidens (Nematoda: Diplogasterida) towards prey and factors influencing attraction

The attraction of Mononchoides longicaudatus and M. fortidens towards prey and factors influencing their attraction were studied on agar plates. These predators were attracted towards excised and non-excised (live) prey in response to prey secretions, attractants. Predators also responded positively towards agar containing unidentified bacteria. M. longicaudatus and M. fortidens showed preference for the prey nematodes which were tested either alive or by cutting into two pieces (excised). Hirschmanniella oryzae, Tylenchorhynchus mashhoodi and Hoplolaimus indicus attracted predators most while Longidorus SP., and Helicotylenchus indicus elicited least response from the predators. The rest of the prey nematodes attracted predators moderately. Both species of predators were also attracted towards their own individuals. Different factors viz., prey number, temperature, incubation period of prey, starvation of predators and distance of predators from prey affected attraction of the predators towards Hirschmanniella oryzae and the second stage juveniles of Meloidogyne incognita. Both predators were attracted in maximum numbers when 50 prey nematodes were incubated for 12 h in Petri-dishes, at 25°-30°. Starvation of predators increased their attraction towards prey; increase in prey distance decreased attraction

Albumin precursorandHsp70modulatecornealwoundhealinginanorgan culturemodel

In order to investigate the role of albumin precursor and Hsp70 in corneal wound healing, we have analyzed the distribution of these proteins in wounded and non-wounded corneas of rabbits and the effects of topical applications of anti-albumin precursor and anti-Hsp70 antibodies on wound healing. Anti-albumin precursor and anti-Hsp70 antibodies were topically applied in healing corneal epithelium of rabbit eyes in organ culture. Corneas were allowed to heal in vitro for up to 120 h in serum-free medium with 5 and 10 μg/ml or without (migrating control) anti-albumin precursor/ or anti-Hsp70 antibodies. Fibronectin (Fb) (5 μg/ml) was used as a positive control. Immunofluorescence labelling was used to detect proteins in corneal epithelium at various time intervals following an epithelial defect. Delay in wound healing (pp120 h with 10 μg/ml. Additionally, immunofluoresence showed a strong co-localization of Hsp70 and albumin precursor during the active phase of wound healing. The presence of albumin precursor and Hsp70 in the epithelial compartment of the cornea indicates a role for these proteins in modulating cell behavior such as epithelial growth, adhesion or regeneration, thus contributing to corneal epithelial wound healing

A study of the intestinal contents of some mononchs

The intestinal contents of over one thousand specimens of thirty three species belonging to nine genera of the order Mononchida were analysed to determine their range and preference for prey. The study showed that mononchs feed upon tylenchs, dorylaims, mononchs and free-living saprophagous nematodes besides rotifers. Cuticular remains of al1 types including trophi of rotifers and other unidentifiable objects of prey were of frequent occurrence. Forty five percent of the predators had prey in their intestine. Feeding of different mononchs is polyvalent and predation aleatory. However, more predators 75% had free-living saprophagous nematodes within the intestine rather than tylenchs (45%) or dorylaims (42%). Pratylenchus, Hoplolaimus, Tylenchorhynchus, Tylencholaimus, Aporcelaimus, Thornenema, Iotonchus, Mylonchulus, Rhabditis, Acrobeloides and Chiloplacus were found most frequently in the intestine of different species of mononchs. Parahadronchus shakili appeared to be most active predator as 68 % of its specimens had prey in their intestine while Coomansus indicus was least active with only 21% having prey. Twenty percent predators were cannibals while 27% devoured mononchs belonging to other species/genera. Mylonchulus spp., and Iotonchus baqrii did not contain any prey or its remains in their intestine. None to eight prey could be present in the intestine of a single predator

Some factors influencing predation by Mononchus aquaticus

This article does not have an abstract

Hepatitis B virus interacts with albumin precursor in vivo

A range of proteins has been recognized as mediators/hypothetical receptors for hepatitis B virus (HBV), but the results are conflicting and inconclusive especially regarding their biological significance. This study was aimed at identifying a novel HBV-interacting protein which would provide a better understanding of its transport in blood, attachment, fusion and entry into hepatocytes. Serum samples positive for HBV confirmed by PCR were subjected to ammonium sulfate fractionations at 50, 75, 100%, saturation. PCR of each fraction demonstrated amplification of HBV in 100% fraction. Protein analysis by SDS PAGE of fractions showed one band of approximately 69 kDa protein, in 100% fraction. The 100% fraction band was excised from gel and sequence was determined by MALDI TOF which showed mass values from 705 to 3722. Mass spectrometry of trypsinized 69 kDa species revealed peptide sequences that covered 54% of the serum albumin precursor amino acid sequence, with pI of 5.9. Western blot, carried out using primary anti-albumin precursor antibody, further validated this protein. This study establishes that Hepatitis B Virus binds to albumin precursor, suggesting its role in the initiation of HBV infection and hence may offer new therapeutic strategies against HBV infection

Craniocerebral aspergillosis: A review of advances in diagnosis and management

Craniocerebral aspergillosis is a rare but dangerous central nervous system infection. The infection has a spectrum of presenting features, mostly affecting immunocompromised individuals. The incidence appears to be on the rise that has been especially observed in the immunocompetent population. A high index of suspicion, a comprehensive understanding of the infectious process and advanced laboratory and radiological diagnostic techniques, allow early diagnosis. Surgery, followed by systemic antifungal medications, remains the cornerstone of management. Early administration of empirical anti-fungal agents along with immunomodulators may further improve prognosis. Immunocompetent patients tend to have better outcomes as compared to those who are immunocompromised. Patients with intradural disease carry the worst prognosis

Crystal structure of [(2R,3R,4S)-3,4-bis-(acetyloxy)-5-iodo-3,4-dihydro-2H-pyran-2-yl]methyl acetate

Acknowledgements We thank Professor Regina H. A. Santos from IQSC–USP for the X-ray data collection. The Brazilian agencies CNPq (305626/2013–2 to JZS; 306121/2013-2 to IC; 308320/2010-7 to HAS) and FAPESP are acknowledged for financial support.Peer reviewedPublisher PD