Cooperation and Competition Shape Ecological Resistance During Periodic Spatial Disturbance of Engineered Bacteria

Cooperation is fundamental to the survival of many bacterial species. Previous studies have shown that spatial structure can both promote and suppress cooperation. Most environments where bacteria are found are periodically disturbed, which can affect the spatial structure of the population. Despite the important role that spatial disturbances play in maintaining ecological relationships, it remains unclear as to how periodic spatial disturbances affect bacteria dependent on cooperation for survival. Here, we use bacteria engineered with a strong Allee effect to investigate how the frequency of periodic spatial disturbances affects cooperation. We show that at intermediate frequencies of spatial disturbance, the ability of the bacterial population to cooperate is perturbed. A mathematical model demonstrates that periodic spatial disturbance leads to a tradeoff between accessing an autoinducer and accessing nutrients, which determines the ability of the bacteria to cooperate. Based on this relationship, we alter the ability of the bacteria to access an autoinducer. We show that increased access to an autoinducer can enhance cooperation, but can also reduce ecological resistance, defined as the ability of a population to resist changes due to disturbance. Our results may have implications in maintaining stability of microbial communities and in the treatment of infectious diseases

Patterns of calcium oxalate monohydrate crystallization in complex biological systems

The paper presents the features of calcium oxalate crystallization in the presence of additives revealed through experimental modeling. The patterns of phase formation are shown for the Ca{2+} – C[2]O[4]{ 2–} – H[2]O and Ca{2+} – C[2]O[4]{2–} – PO[4]{3–} – H[2]O systems with the components and pH of the saline varying over a wide concentrations range. The effect of additives on crystallization of calcium oxalate monohydrate was investigated. It was found that the ionic strength and magnesium ions are inhibitors, and calcium oxalate and hydroxyapatite crystals are catalysts of calcium oxalate monohydrate crystallization. The basic calcium phosphate (apatite) was found to be most thermodynamically stable, which indicates its special role in kidney stone formation since it is found in virtually all stones

American palm ethnomedicine: A meta-analysis

<p>Abstract</p> <p>Background</p> <p>Many recent papers have documented the phytochemical and pharmacological bases for the use of palms (<it>Arecaceae</it>) in ethnomedicine. Early publications were based almost entirely on interviews that solicited local knowledge. More recently, ethnobotanically guided searches for new medicinal plants have proven more successful than random sampling for identifying plants that contain biodynamic ingredients. However, limited laboratory time and the high cost of clinical trials make it difficult to test all potential medicinal plants in the search for new drug candidates. The purpose of this study was to summarize and analyze previous studies on the medicinal uses of American palms in order to narrow down the search for new palm-derived medicines.</p> <p>Methods</p> <p>Relevant literature was surveyed and data was extracted and organized into medicinal use categories. We focused on more recent literature than that considered in a review published 25 years ago. We included phytochemical and pharmacological research that explored the importance of American palms in ethnomedicine.</p> <p>Results</p> <p>Of 730 species of American palms, we found evidence that 106 species had known medicinal uses, ranging from treatments for diabetes and leishmaniasis to prostatic hyperplasia. Thus, the number of American palm species with known uses had increased from 48 to 106 over the last quarter of a century. Furthermore, the pharmacological bases for many of the effects are now understood.</p> <p>Conclusions</p> <p>Palms are important in American ethnomedicine. Some, like <it>Serenoa repens </it>and <it>Roystonea regia</it>, are the sources of drugs that have been approved for medicinal uses. In contrast, recent ethnopharmacological studies suggested that many of the reported uses of several other palms do not appear to have a strong physiological basis. This study has provided a useful assessment of the ethnobotanical and pharmacological data available on palms.</p

Cloud technologies in teaching modeling of complex systems

Purposeful and systematic teaching of the method of modeling brings students closer to the methods of scientific knowledge, ensures their intellectual development. But for this purpose it is necessary to have at one's disposal a whole range of means and tools, which will allow to pass a way from creating a model to checking its consistency and adequacy. If we speak about sufficiently complex objects of research, computing resources required for calculation can significantly exceed the capabilities of a student's personal computer and the modeling process itself can take an indefinite amount of time. Just in this case the cloud systems come to the rescue, which can provide the necessary resources to calculate the model

Adsorption from Binary Gas Mixtures and its Theoretical Description

The experimental and theoretical investigation of adsorption of a number of binary gas mixtures on graphitized thermal black (GTB), on black TG-10 and on silochrome S-80 was carried out to discover the thermodynamic characteristics of the adsorbed substance, when the surface concentration of component 1 was very small and the concentration of component 2 was varied over rather wide limits. The adsorption was measured by the gas chromatographic method. The dependence of the Henry constant, K 1 , of the component 1 on the degree of coverage, θ 2 , of the adsorbent surface by the adsorbed component 2 was determined. For the theoretical description of the adsorption data obtained on the homogeneous GTB surface three models were used: (a) two-dimensional lattice model of adsrption from gas mixture in the Bragg–Williams approximation; (b) the well-known model of non-localized (mobile) adsorption on the basis of two-dimensional van der Waals' equation of state; (c) unidimensional lattice model of adsorbing surface which takes into account the interaction between the neighbouring adsorbed molecules. For the last model the exact solution was obtained by the matrix method. The numerical calculations with the suitably chosen parameters were carried out using the limiting forms of the isotherm equations for the dependence of K 1 on θ 2 . The results of calculations were compared with experimental data

СПЕКТРОСКОПІЯ КООПЕРАТИВНИХ ЛАЗЕРНИХ ЕЛЕКТРОННО-ГАММАЯДЕРНИХ ПРОЦЕСІВ У БАГАТОАТОМНИХ МОЛЕКУЛАХ: OsO4

The consistent quantum approach to calculating the electron-nuclear g transition spectra (a set of the vibration-rotational satellites in a spectrum of molecule) of a nucleus in the multiatomic molecules is used to obtain the accurate data on the vibration-nuclear transition probabilities in a case of the emission and absorption spectrum of the nucleus 188Os (E(0) g = 155 ke V) in the molecule of OsO4 . Analysis shows that more sophisticated theoretical approach gives the higher values for the cited probabilities.Последовательный квантовый подход к расчету электронно-гамма-ядерного спектра (система колебательно-вращательных спутников в спектре молекуле) в многоатомных молекулах используется, чтобы получить уточненные данные о вероятностях колебательноядерных переходов в молекуле OsO4 в случае испускания и поглощения гамма-кванта ядром 188Os (E(0) g = 155 kэВ). Анализ показывает, что более последовательный теоретический подход дает более высокие значения искомых вероятностей.Послідовний квантовий підхід до розрахунку електронно-гамма-ядерного спектру (система коливально-обертальних супутників у спектрі молекули) в багатоатомних молекулах використовується, щоб отримати уточнені дані по ймовірностям коливально-ядерних переходів в молекулі OsO4 у випадку випромінювання та поглинання гамма-кванта ядром 188Os (E(0) g = 155 кеВ). Аналіз показує, що більш послідовний теоретичний підхід дає більш високі значення шуканих ймовірностей

КВАНТОВО-ХІМІЧНЕ ВИВЧЕННЯ СТРУКТУРИ І ДИНАМІКИ РЕЛАКСАЦІЇ ТРІМЕТІН-ЦІАНІНОВОГО БАРВНИКА

Quantum-chemical studying polymethine dyes molecular structure and investigation of the relaxation processes of excitation have been carried out. Particularly, in the highly excited triplet state the dissociative surface exists, which corresponds to σ → σ*-excitation of the molecule; relaxation of excitations in the framework of this surface leads to dissociation of the molecule by lengthening the C-C bond of the molecule at the central carbon atom.Приведены результаты квантово-химического изучения молекулярной структуры и процессов релаксации возбуждения полиметиновых красителей. В частности, в сильно возбужденном триплетном состоянии существует поверхность диссоциации, отвечающая возбуждению σ → σ * молекулы; релаксация возбуждения приводит к диссоциации молекулы за счет удлинения CC связи молекулы на центральном атоме углерода.Приведені результати квантово-хімічного вивчення молекулярної структури та процесів релаксаціїв збудження поліметинових барвників. Зокрема, в сильно збудженому триплетному стані існує поверхня дисоціації, що відповідає збудженню σ→σ* молекули; релаксація збудження приводить до дисоціації молекули за рахунок подовження CC зв’язку молекули на центральному атомі вуглецю