When is star formation episodic? A delay differential equation negative feedback model

We introduce a differential equation for star formation in galaxies that incorporates negative feedback with a delay. When the feedback is instantaneous, solutions approach a self-limiting equilibrium state. When there is a delay, even though the feedback is negative, the solutions can exhibit cyclic and episodic solutions. We find that periodic or episodic star formation only occurs when two conditions are satisfied. Firstly the delay timescale must exceed a cloud consumption timescale. Secondly the feedback must be strong. This statement is quantitatively equivalent to requiring that the timescale to approach equilibrium be greater than approximately twice the cloud consumption timescale. The period of oscillations predicted is approximately 4 times the delay timescale. The amplitude of the oscillations increases with both feedback strength and delay time. We discuss applications of the delay differential equation (DDE) model to star formation in galaxies using the cloud density as a variable. The DDE model is most applicable to systems that recycle gas and only slowly remove gas from the system. We propose likely delay mechanisms based on the requirement that the delay time is related to the observationally estimated time between episodic events. The proposed delay timescale accounting for episodic star formation in galaxy centers on periods similar to P 10 Myrs, irregular galaxies with P 100 Myrs, and the Milky Way disk with P~ 2Gyr, could be that for exciting turbulence following creation of massive stars, that for gas pushed into the halo to return and interact with the disk and that for spiral density wave evolution, respectively.Comment: submitted to MNRA

Entry of Yersinia pestis into the Viable but Nonculturable State in a Low-Temperature Tap Water Microcosm

Yersinia pestis, the causative agent of plague, has caused several pandemics throughout history and remains endemic in the rodent populations of the western United States. More recently, Y. pestis is one of several bacterial pathogens considered to be a potential agent of bioterrorism. Thus, elucidating potential mechanisms of survival and persistence in the environment would be important in the event of an intentional release of the organism. One such mechanism is entry into the viable but non-culturable (VBNC) state, as has been demonstrated for several other bacterial pathogens. In this study, we showed that Y. pestis became nonculturable by normal laboratory methods after 21 days in a low-temperature tap water microcosm. We further show evidence that, after the loss of culturability, the cells remained viable by using a variety of criteria, including cellular membrane integrity, uptake and incorporation of radiolabeled amino acids, and protection of genomic DNA from DNase I digestion. Additionally, we identified morphological and ultrastructural characteristics of Y. pestis VBNC cells, such as cell rounding and large periplasmic spaces, by electron microscopy, which are consistent with entry into the VBNC state in other bacteria. Finally, we demonstrated resuscitation of a small number of the non-culturable cells. This study provides compelling evidence that Y. pestis persists in a low-temperature tap water microcosm in a viable state yet is unable to be cultured under normal laboratory conditions, which may prove useful in risk assessment and remediation efforts, particularly in the event of an intentional release of this organism

A local human Vδ1 T cell population is associated with survival in nonsmall-cell lung cancer

Murine tissues harbor signature γδ T cell compartments with profound yet differential impacts on carcinogenesis. Conversely, human tissue-resident γδ cells are less well defined. In the present study, we show that human lung tissues harbor a resident Vδ1 γδ T cell population. Moreover, we demonstrate that Vδ1 T cells with resident memory and effector memory phenotypes were enriched in lung tumors compared with nontumor lung tissues. Intratumoral Vδ1 T cells possessed stem-like features and were skewed toward cytolysis and helper T cell type 1 function, akin to intratumoral natural killer and CD8(+) T cells considered beneficial to the patient. Indeed, ongoing remission post-surgery was significantly associated with the numbers of CD45RA(-)CD27(-) effector memory Vδ1 T cells in tumors and, most strikingly, with the numbers of CD103(+) tissue-resident Vδ1 T cells in nonmalignant lung tissues. Our findings offer basic insights into human body surface immunology that collectively support integrating Vδ1 T cell biology into immunotherapeutic strategies for nonsmall cell lung cancer

A local human Vδ1 T cell population is associated with survival in nonsmall-cell lung cancer

Murine tissues harbor signature γδ T cell compartments with profound yet differential impacts on carcinogenesis. Conversely, human tissue-resident γδ cells are less well defined. In the present study, we show that human lung tissues harbor a resident Vδ1 γδ T cell population. Moreover, we demonstrate that Vδ1 T cells with resident memory and effector memory phenotypes were enriched in lung tumors compared with nontumor lung tissues. Intratumoral Vδ1 T cells possessed stem-like features and were skewed toward cytolysis and helper T cell type 1 function, akin to intratumoral natural killer and CD8+ T cells considered beneficial to the patient. Indeed, ongoing remission post-surgery was significantly associated with the numbers of CD45RA−CD27− effector memory Vδ1 T cells in tumors and, most strikingly, with the numbers of CD103+ tissue-resident Vδ1 T cells in nonmalignant lung tissues. Our findings offer basic insights into human body surface immunology that collectively support integrating Vδ1 T cell biology into immunotherapeutic strategies for nonsmall cell lung cancer

Nutrition and health claims in legal regulations and opinions of consumers

W artykule dokonano przeglądu aktów prawnych regulujących umieszczanie oświadczeń żywieniowych i zdrowotnych na opakowaniach produktów żywnościowych w Unii Europejskiej. Ponadto przedstawiono wybrane wyniki badań na temat sposobu postrzegania oświadczeń przez konsumentów. Opakowanie jest pierwszym elementem produktu żywnościowego, z którym konsument ma kontakt i tym samym wydaje się być odpowiednim miejscem do komunikowania się z nim. W roku 2006 uchwalono Rozporządzenie nr 1924/2006 (WE) w sprawie stosowania oświadczeń żywieniowych i zdrowotnych w krajach Unii Europejskiej, które zawiera zharmonizowane zasady posługiwania się przez podmioty obecne na rynku oświadczeniami w odniesieniu do żywności. Zgodnie z tym aktem prawnym za oświadczenia uznaje się wszelkie komunikaty sugerujące, że produkt żywnościowy charakteryzuje się szczególnymi właściwościami. Producenci chętnie wykorzystują oświadczenia w etykietowaniu, aby podkreślić w łaściwości danego produktu lub korzyści zdrowotne płynące z jego spożycia. Stosowanie tych informacji przez producentów jest odpowiedzią na oczekiwania konsumentów, którzy w coraz większym stopniu zauważają zależność pomiędzy dietą a zdrowiem. Wyniki dotychczas przeprowadzonych badań dowodzą, że oświadczenia żywieniowe i zdrowotne mogą wpływać na postrzeganie przez konsumentów poszczególnych cech produktu, a także ogólnej oceny jego jakości, brak jednak jednoznacznych danych, że umieszczenie oświadczeń skłoni konsumentów do wyboru produktów korzystniejszych dla zdrowia. Kluczowym zagadnieniem jest również problem interpretacji i rozumienia treści oświadczeń przez konsumentów.The paper is a review of legal regulations regulating the inserting of nutrition and health claims on the packaging of food products in the European Union. Moreover, some selected research results are presented on how the consumers perceive those claims. The packaging is the first element of food product to contact the consumer and, therefore, it seems to be a proper means to communicate with them. In December 2006, Regulation (EC) No. 1924/2006 was adopted on the use of nutrition and health claims in the EU countries; it contains harmonised provisions on the use of claims made on food by entities present on the market. According to this legal act, ‘claim’ is any communication, which suggests that a food product has particular characteristics. Manufacturers willingly utilize claims to label foods in order to highlight properties of a given food product or its health benefits when consuming it. The application of such information is a response to the expectations of consumers who are more and more aware of the relationship between diet and health. The results of the hitherto studies confirm that the nutrition and health claims may impact the consumer perception of individual attributes of a product and their overall evaluation of its quality. However, there are no clear data indicating that a claim placed on the label can convince consumers to choose products that are more beneficial to health. The key issue is also how consumers understand and interpret the contents of nutrition and health claims

The agricultural and food products adulteration in the eyes of the legal regulations and activities of the offi cial food control authorities in Poland

The aim of the research was to present legal regulations concerning adulteration on the market of agricultural and food products, and the effects of actions taken by IJHARS in this regard. The study has covered the Polish and EU legal regulations concerning the issues of irregularities and of the liability of entrepreneurs on the foodstuffs market. This goal has been achieved by analysing secondary data, i.e. legal acts and the available results of the inspections conducted in 2009–2017 by the official food control authorities. The administrative decisions issued by IJHARS pursuant to Article 29 of the Act on Merchantable Quality of Agricultural and Food Products, concerning the adulteration of agricultural and food products, which are published on the Inspection’s website, have been analysed in particular detail. The results of the control activities indicate that further control activities are justified, in particular with regard to food labelling.</jats:p