Neutral theory of chemical reaction networks

To what extent do the characteristic features of a chemical reaction network reflect its purpose and function? In general, one argues that correlations between specific features and specific functions are key to understanding a complex structure. However, specific features may sometimes be neutral and uncorrelated with any system-specific purpose, function or causal chain. Such neutral features are caused by chance and randomness. Here we compare two classes of chemical networks: one that has been subjected to biological evolution (the chemical reaction network of metabolism in living cells) and one that has not (the atmospheric planetary chemical reaction networks). Their degree distributions are shown to share the very same neutral system-independent features. The shape of the broad distributions is to a large extent controlled by a single parameter, the network size. From this perspective, there is little difference between atmospheric and metabolic networks; they are just different sizes of the same random assembling network. In other words, the shape of the degree distribution is a neutral characteristic feature and has no functional or evolutionary implications in itself; it is not a matter of life and death.Comment: 13 pages, 8 figure

Species Abundance Patterns in Complex Evolutionary Dynamics

An analytic theory of species abundance patterns (SAPs) in biological networks is presented. The theory is based on multispecies replicator dynamics equivalent to the Lotka-Volterra equation, with diverse interspecies interactions. Various SAPs observed in nature are derived from a single parameter. The abundance distribution is formed like a widely observed left-skewed lognormal distribution. As the model has a general form, the result can be applied to similar patterns in other complex biological networks, e.g. gene expression.Comment: 4 pages, 3 figures. Physical Review Letters, in pres

Predicate constituent order variation in the Spanish-Quechua contact situation of Cusco, Peru

This study examines predicate constituent order variation (object-verb/verb-object) in the varieties of Andean Spanish and Quechua spoken in Cusco. Though the investigated languages exhibit mirror-image ordering typologies— VO-dominant order in Andean Spanish and OV-dominant order in Quechua—a relatively high incidence of non-canonical order is attested in both languages, as exemplified in (1) and (2). In Andean Spanish, OV order occurs at a rate ranging from 17-28% (Klee 1996; Muntendam 2009; Muysken 1984; Ocampo & Klee 1995), which exceeds the rates reported for non-contact varieties, like Rio Platense Spanish, 6.9% (Ocampo 1995). Similarly, predicate constituent order is quite variable in Quechua, with non-canonical VO order rates ranging from 10.8% to 85.1% depending on the region and data elicitation method (Kalt & Geary 2021; Sánchez 2003). In general, predicate constituent order variation in both languages is attributed to indirect contact, though social factors (e.g. socioeconomic status) and linguistic factors (e.g., information structure) also reportedly condition variation in this syntactic domain. Using naturalistic speech data elicited via Sociolinguistic Interviews from monolingual (Andean Spanish) and bilingual (Andean Spanish-Quechua) Cusqueño participants, I conclude that variable predicate constituent order constitutes a linguistic change mediated by language contact. Applying the relevant criteria for establishing contact-induced change advanced by Poplack & Levey (2010), I compare OV/VO variation in each language in both a vertical (i.e., current versus earlier versions of a language) and horizontal (i.e., recipient versus source language) fashion. Concerning the former, through an apparent-time analysis I find an inverse correlation between age and VO order frequency in both Andean Spanish and Quechua. This finding suggests a change in progress in which OV/VO variation is moving toward the prescriptive norm in Andean Spanish and moving away from the prescriptive norm in Quechua. Next, through a horizontal comparison I find evidence of two parallel structures—OV order with demonstrative and universally-quantified pronominal objects and VO order with explicit subjects, as illustrated in (3) and (4), respectively. I argue that, taken together, the change in progress and existence of parallel structures constituent evidence of bidirectional contact-induced change in the Quechua-Spanish contact situation regarding predicate constituent order variation

Electron-based crystalline undulator

We discuss the features of a crystalline undulator of the novel type based on the effect of a planar channeling of ultra-relativistic electrons in a periodically bent crystals. It is demonstrated that an electron-based undulator is feasible in the tens of GeV range of the beam energies, which is noticeably higher than the energy interval allowed in a positron-based undulator. Numerical analysis of the main parameters of the undulator as well as the characteristics of the emitted undulator radiation is carried out for 20 and 50 GeV electrons channeling in diamond and silicon crystals along the (111) crystallographic planes.Comment: 16 pages, 8 figures, Latex, IOP styl

Calibrating and testing tissue equivalent proportional counters with 37Ar

A method for testing and calibrating tissue equivalent proportional counters with37Ar is described.37Ar is produced by exposure of argon in its normal isotope composition to thermal neutrons. It is shown that - up to volume ratios of 0.01 of argon to the tissue equivalent gas - there is no appreciable effect of the argon admixture on the function of the proportional counter. Conventional calibration methods with characteristic x-rays or with -particles require modifications of the detectors, and they test only small sub-volumes in the counters. In contrast, argon permits calibrations and tests of the resolution that are representative for the entire counter volume and that do not require changes in detector construction. The method is equally applicable to multi-element proportional counters; it is here exemplified by its application to a long cylindrical counter of simplified design that is part of such a multi-element configuration

Electromagnetic Cascades and Cascade Nucleosynthesis in the Early Universe

We describe a calculation of electromagnetic cascading in radiation and matter in the early universe initiated by the decay of massive particles or by some other process. We have used a combination of Monte Carlo and numerical techniques which enables us to use exact cross sections, where known, for all the relevant processes. In cascades initiated after the epoch of big bang nucleosynthesis $\gamma$-rays in the cascades will photodisintegrate $^4$He, producing $^3$He and deuterium. Using the observed $^3$He and deuterium abundances we are able to place constraints on the cascade energy deposition as a function of cosmic time. In the case of the decay of massive primordial particles, we place limits on the density of massive primordial particles as a function of their mean decay time, and on the expected intensity of decay neutrinos.Comment: compressed and uuencoded postscript. We now include a comparison with previous work of the photon spectrum in the cascade and the limits we calculate for the density of massive particles. The method of calculation of photon spectra at low energies has been improved. Most figures are revised. Our conclusions are substantially unchange

Fire Blight of Pears and Apples

This fact sheet describes fire blight, a bacterial disease of concern to apple and pear growers, and how it can be managed

Placeholder na in Quechua-Spanish bilinguals

Placeholder na in Quechua-Spanish bilinguals The current study analyzes the lexical item na in Cusco-Callao Quechua (Southern Peru), illustrated in (1) below. Using sociolinguistic interview data from bilingual (Quechua/Spanish) speakers from the Cusco region, we observe two primary uses of na. First, it functions as what Fox (2010) refers to as a “placeholder filler” (henceforth ‘placeholder’ similar to English ‘whatchamacallit’) to stand in for another word in the discourse (1-2) (see also Seraku 2024). Second, Nobel and Lacasa (2007) observe that na can be “used alone as a hesitation filler while the speaker is contemplating the next word, but it must have affixed to it the particle that would be affixed to the missing word” (226). In the Quechua data, our analysis reveals patterns, not yet described in the literature, in which na is used with reference to taboo or sensitive topics. Moreover, our Spanish data demonstrate considerable borrowing of na, where it varies with other hesitation markers, such as mm and pues. Hornberger and Hornberger (2013) describe Quechua na as “a declinable and conjugatable root used to take place of a forgotten or deleted word” (65). In (1) na is affixed to a locative marker pi ‘in’, and with example (2), na is affixed to both a locative marker and person/number inflection. For example (1), na may be interpreted as a typical placeholder, allowing the speaker to fill the pause while recalling the name of a location (Ururu). In (2) the lexical item substituted with na is made clear in context, where the speaker uses na to avoid referring directly to his father’s death, mentioned previously in the discourse—as in wañu-pu-n ‘he died.’ Using sociolinguistic interview data, we demonstrate that na is used both to mark hesitations, as shown in (3) and (4), and to stand in for another word, as in (5), which demonstrates that, like Quechua, na can be inflected depending on the lexical class it replaces—i.e. na-r for verbs. Our data suggest that cases of inflected na with Spanish/Quechua bilinguals are infrequent, particularly when compared to its use as a hesitation marker. More generally, our study illustrates that discourse structures in peripheral domains (e.g., placeholders and hesitation markers) are subject to borrowing and that they often display meanings akin to their source (see Zavala 2001 for pues in Andean Spanish). Examples (1) ¿Na-pi… Ururu-pi ka-sa-ncheh-ña? (Nobel and Lacasa 2007: 226) NA-loc Ururu-loc be-prog-1pl.incl-yet ‘Eh…are we in Ururu yet?’ (2) chayman hinay papa-y-pis nishu-ta macha-pu-qti-n, na-pu-n then thusly father-1sg.poss- conj much-adv drink-loc-sub-3sg NA-loc-3sg ‘Then, thusly, my father, having drunk a lot, FP-ed’ (3) Mm, ya, yo también aquí en Chinchero yo nacido y na aquí siempre vevemos aquí ‘Mm, okay, I too, here in Chinchero, was born and NA here we always live’ (4) estamos haciendo puskha. Para manta, para poncho, para na, para frasar tiene que ser grueso ‘we are spinning [wool]. For blankets, for ponchos, for NA, for clothing it has to be thick’ (5) De repente a nosotros, como nosotros, trabajamos pequeñas… de repente se va a nar… mm se va desaparecer ‘Maybe to us, because we work little… maybe it will NA… mm it will disappear’ References Fox, B. 2010. Introduction. In Fillers, Pauses and Placeholders, ed. by Nino Amiridze, Boyd H. Davis, and Margaret Maclagan, 1-9. Amsterdam/Philadelphia: John Benjamins. Hornberger, E.S. and N.H. Hornberger. 2013. Diccionario trilingüe Quechua de Cusco: Qhiswa, English, Castellano, 4ta edición. Cusco, Perú: Centro Bartolomé de las Casas. Noble, J. and J. Lacasa. 2007. Introduction to Quechua: Language of the Andes, 2nd Edition. Indianapolis: Dog Ear Publishing. Seraku, T. 2024. Placeholders in crosslinguistic perspective: abilities, preferences, and usage motives. Linguistics. https://doi.org/10.1515/ling-2023-0068 Zavala, V. 2001. Borrowing evidential functions from Quechua: The role of pues as a discourse marker in Andean Spanish. Journal of Pragmatics 33.999-1023