We discuss the form of the spin operator in relativistic quantum mechanics. We derive the form of the spin operator in the case when the states with negative energies are admitted. It appears that ...for a Dirac particle the spin operator reduces to the so called mean-spin operator introduced by Foldy and Wouthuysen. We show that the spin operator transforms under Lorentz group action according to an operator Wigner rotation, analogously as a Bloch vector describing polarization of a particle in momentum representation.
► We examine the problem of a relativistic spin operator in the case of a Dirac particle. ► We show that a proper spin operator coincides for positive energies with the operator used in quantum field theory. ► This operator can be extended for negative energies. ► We show that this operator is equivalent to the so called mean-spin operator introduced by Foldy and Wouthuysen. ► The spin operator transforms under Lorentz group action according to the operator Wigner rotation.
A “canned corn-like” odor was periodically detected at Philadelphia's Northeast Water Pollution Control Plant (NEWPCP) for more than two decades. Previous research concluded that it was caused by ...dimethyl sulfide (DMS), from the reduction of dimethyl sulfoxide (DMSO) discharged by a local industrial customer. Several process modifications were implemented at the industrial site to eliminate the “canned corn-like” odor. Results showed that enhancing DMSO recovery by 25% and equalizing the aqueous wash discharge over a longer period of time reduced the DMSO source peak discharge from 1124 to 49
kg/h, and the peak concentrations of DMSO and DMS at the NEWPCP by 81 and 88%. Reduction of DMSO discharge by segregating the first wash for off-site disposal further reduced the peak discharge of DMSO from 49 to 18
kg/h at the source, and DMSO and DMS concentrations at the NEWPCP by 48 and 92%. Segregation of the dehydration distillate for off-site disposal reduced DMSO discharge by 3
kg/h. Modifications by concentrating a higher percentage of the DMSO into the first wash and increasing the DMSO solvent recovery by an additional 33% reduced the total DMSO discharge from 522 to 200
kg and peak discharge rate from 15 to 6
kg/h. All of these process modifications collectively reduced the DMSO source discharge by 92% and the DMSO concentration received at NEWPCP by 97%, from 12
mg/L to ∼500
μg/L. At this reduced concentration, the company's wastewater discharge was no longer found to cause the “canned corn” odor at the fence line of NEWPCP, thereby mitigating any further need for odor control.
Hordeum vulgare L. cv. Bartom seedlings grown on a substrate without or with zeolite were exposed to 450 and 1,000 µmol of Cd(NO₃)₂. Adding the zeolite to a substrate (+Si) resulted in the ...accumulation of mono- and polysilicic acids in the leaves, an increase in the growth of seedlings and biomass production, a decrease of the contents of thiobarbituric acid reactive substances (TBARs), and an increase in the activities of the antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX). The negative effects of Cd²⁺, which were reflected in loss of chlorophyll contents and a decrease of the photosynthesis rate, as well as an increase of TBARs contents were observed in the (−Si)-plants to a greater extent than in the (+Si)-plants. The activities of SOD, APX and GPX increased in the barley leaves of (−Si)- and (+Si)-seedlings with an increase of Cd²⁺concentration in the acting solution. At the same time the values of the ratios between TBARs concentrations and the activities of SOD, APX and GPX in (−Si)-plants were higher than that in (+Si)-plants both under optimal conditions and with Cd stress. This suggests that the use of Si-rich mineral zeolite for growing barley stimulates metabolism and increases the resistance of plants to cadmium stress through a shift in the dynamic equilibrium between the rate of oxidative destruction and the activity of antioxidant systems in favor of the latter.
View From the Inside: Older Adults Nevins, Andrea; Wodarczyk, Ceraldine M.
The Gerontologist,
10/1996, Letnik:
36, Številka:
5
Journal Article, Book Review
Recenzirano
Odprti dostop
The video "View From the Inside: Older Adults" is reviewed.
The replicon of the pTAV3 megaplasmid (approx. 400 kb) of Paracoccus versutus has been localized to a 4center dot3 kb EcoRI restriction fragment and its entire nucleotide sequence determined. The G+C ...content of the entire sequence is 66 mol%, which is within the range (62-66 mol%) previously determined for P. versutus total DNA. ORF1 encodes a replication initiation protein Rep (47.2 kDa), which shares substantial similarity with putative proteins of the Coxiella burnetii plasmids QpH1 and QpDV, and the replication protein of Pseudomonas syringae plasmid pPS10. ORF2, located in the opposite transcriptional orientation to ORF1, encodes a putative protein that shares similarity to a subfamily of ATPases involved in plasmid partitioning. The highest similarity was observed with homologous proteins (RepA) encoded by the repABC family of replicons found in several plasmids of Agrobacterium, Rhizobium and Paracoccus spp. The predicted product of ORF3 was similar to AcoR, Nif and NtrC transcriptional activators. A strong incompatibility determinant (inc) was localized between ORF1 (rep) and ORF2 (parA). The origin of replication of pTAV400 contains a short A+T-rich region and several imperfect palindromic sequences. Curing experiments demonstrated that the megaplasmid bears genes required for growth in minimal media and can therefore be referred to as a mini-chromosome. Megaplasmids pTAV3 of P. versutus UW1 and pKLW2 of Paracoccus pantotrophus DSM 11073 were found to carry closely related, incompatible replicons. It has been shown that plasmid pORI6 (containing oriV of pTAV3 cloned into plasmid pABW1, which does not replicate in Paracoccus spp.) can be trans activated not only by pTAV3, but also by pKLW2. Using pORI6, it was demonstrated that replication systems related to pTAV3 are also present in the replicons of Paracoccus alcaliphilus JCM 7364, Paracoccus thiocyanatus IAM 12816 and Paracoccus methylutens DM 12.
The ZEUS calorimeter first level trigger Silverstein, S.; Ali, I.; Behrens, B. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/1995, Letnik:
360, Številka:
1-2
Journal Article
Recenzirano
An overview of the ZEUS calorimeter first level trigger is presented. The CFLT uses a pipelined architecture to accept and analyze calorimeter data for every 96 ns beam crossing interval. PMT signals ...are combined by analog electronics into electromagnetic and hadronic sums for 896 trigger towers. The analog sums are then digitized and analyzed. The CFLT determines the total, transverse, and missing transverse energy, identifies isolated electrons and muons, and sums energies in programmable subregions. Calculations are performed in 96 ns steps, and new data are accepted for every beam crossing. Trigger data are forwarded to the global first level trigger (GFLT) after 2 μs, allowing a GFLT accept to be issued 5 μs after the beam crossing which produced the event. Important features of the CFLT include a 12-bit effective dynamic range, extensive use of memory lookup tables for trigger calculations, fast pattern searches for isolated leptons, and low electronics noise. During the 1993 HERA run, the CFLT reduced a 50 kHz background rate to around 100 Hz.
Barley (Hordeum vulgare L.) seeds were soaked in aqueous 10⁻⁴ M dihydroquercetin (DHQ) to examine its influence on seed germination and further growth of seedlings under optimal soil watering and ...flooding conditions. The adaptive potential of the plants was estimated by the content of thiobarbituric acid reactive substances (TBARs) and the activity of ascorbate peroxidase (AsP). High-grade seeds were germinated evenly under (-DHQ)- and (+DHQ)-treatments. Low-grade seeds soaked in DHQ, showed no mold and twofold germination rate in comparison with the same seeds soaked in water. The seedlings grown from the similarly germinated seeds did not differ from each other in the shoot growth, independent of the DHQ-pretreatment. The root growth was higher in DHQ-pretreated plants. Soil flooding suppressed the shoot and root growth rates in non-pretreated and DHQ-pretreated plants, however TBARs content was lower in the roots and leaves of (+DHQ)-seedlings as compared to the (-DHQ)-ones. The activity of AsP increased more significantly in the (+DHQ)-plants. The ratio between TBARs content and the AsP activity was lower in the leaves of (+DHQ)-plants both under optimal soil conditions and flooding. Thus, the treatment of low-grade barley seeds with DHQ protects the seeds against mold and increases adaptive potential of the seedlings.
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