Nestedness in mutualistic networks

James et al. (2012) presented simulations that apparently falsify the analytical result by Bastolla et al. (2009), who showed that nested mutualistic interactions decrease interspecific competition and increase biodiversity in model ecosystems. This contradiction, however, mainly stems from the incorrect application of formulas derived for fully connected networks to empirical, sparse networks.Comment: 2 pages, 1 figur

Cold Connections as Used by the Metalsmith and Sculptor

Metal may be joined to metal and non-metal materials by many techniques. It is my intent to discuss one group of such techniques--that of cold connections, and illustrate them with art works. Although there are many types of cold connections, this study will concentrate on the use of rivets, screws, bolts, adhesives, nails and wire as cold connectors. A proper definition for cold connection is attachment of one piece of material to another piece of material without use of heat. Historical reference of the uses of cold connections by prehistoric man, early civilizations of man, through modern times is included in the preface. Truly, cold connections have aided man in the conquest of his environment, providing a means for disassembly, with a possibility of reassembly for any movement of the connected objects. As the methods of cold connection are sometimes underappreciated and overlooked for a myriad of reasons, a philosophy and a list of reasons to use cold connections is included in the introduction. One should be mindful that use of cold connections may become an end in itself--reducing the piece to possible showmanship only. Each type of cold connection has been researched as to varieties available, historical use, advantages and disadvantages and manners of correct use in a section preceding examples of my work (text and illustrations). Observations as to the effectiveness of the chosen cold connection and other techniques used in each piece are listed at the end of each text. I chose to investigate a limited number of cold connections. Knowing a little about several types of cold connections has been more advantageous than knowing a great deal about one type of cold connection. Resultant frustration, boredom, the lack of creative approaches to my work, and the lack of enthusiasm have not influenced my research because I have limited knowledge of each type of cold connection I chose. The ideas were plentiful and the pieces were more than just satisfactorily completed. One could develop quite an extensive discussion on any one type of cold connection successfully. The information is easy to obtain and is quite interesting. As technology provides new materials for mankind to join together, and new techniques and materials for joining, one will either use the existing types of cold connections, re-design them, or will develop new types to fit his needs. The extent of an investigation of the uses of cold connections by a sculptor and metalsmith appears interminable

Constitutional Foundations of the United States Navy

The article examines the attention the navy received during the debate over the ratification of the Constitution in 1787-1788.1 It rests on the normative supposition that naval personnel who have taken an oath to uphold the Constitution will have a serious interest in the organic connection between their chosen branch of military service and the document they are sworn to uphold

Book Review. - Literatur

Book Review. - Literatu

Field-induced transition of the magnetic ground state from A-type antiferromagnetic to ferromagnetic order in CsCo2Se2

We report on the magnetic properties of CsCo$_2$Se$_2$ with ThCr$_2$Si$_2$ structure, which we have characterized through a series of magnetization and neutron diffraction measurements. We find that CsCo$_2$Se2$_2$ undergoes a phase transition to an antiferromagnetically ordered state with a N\'eel temperature of $T_{\rm N} \approx$ 66 K. The nearest neighbour interactions are ferromagnetic as observed by the positive Curie-Weiss temperature of $\Theta \approx$ 51.0 K. We find that the magnetic structure of CsCo$_2$Se$_2$ consists of ferromagnetic sheets, which are stacked antiferromagnetically along the tetragonal \textit{c}-axis, generally referred to as A-type antiferromagnetic order. The observed magnitude of the ordered magnetic moment at $T$ = 1.5 K is found to be only 0.20(1)$\mu_{\rm Bohr}$/Co. Already in comparably small magnetic fields of $\mu_0 H_{MM}$(5K) $\approx$ 0.3 T, we observe a metamagnetic transition that can be attributed to spin-rearrangements of CsCo$_2$Se$_2$, with the moments fully ferromagnetically saturated in a magnetic field of $\mu_0 H_{\rm FM}$(5K) $\approx$ 6.4 T. We discuss the entire experimentally deduced magnetic phase diagram for CsCo$_2$Se$_2$ with respect to its unconventionally weak magnetic coupling. Our study characterizes CsCo$_2$Se$_2$, which is chemically and electronically posed closely to the $A_xFe_{2-y}Se_2$ superconductors, as a host of versatile magnetic interactions

Correlation potentials for molecular bond dissociation within the self-consistent random phase approximation

Self-consistent correlation potentials for H$_2$ and LiH for various inter-atomic separations are obtained within the random phase approximation (RPA) of density functional theory. The RPA correlation potential shows a peak at the bond midpoint, which is an exact feature of the true correlation potential, but lacks another exact feature: the step important to preserve integer charge on the atomic fragments in the dissociation limit. An analysis of the RPA energy functional in terms of fractional charge is given which confirms these observations. We find that the RPA misses the derivative discontinuity at odd integer particle numbers but explicitly eliminates the fractional spin error in the exact-exchange functional. The latter finding explains the accurate total energy in the dissociation limit.Comment: 9 pages, 10 figure

Chronic pain: the importance of a sex and gender-based approach to treatment

Twenty-eight million women in the United States suffer from chronic pain. 70% of patients seeking treatment for chronic pain are women, and are found to return to pain clinics thirty-two times more frequently than men. These findings indicate that women experience insuficient pain relief following intervention. Given that 80% of pain research has been conducted on men, most knowledge of pain pathways in women are extrapolations, shedding light on the ineficiencies of current treatment algorithms, and the importance of a sex and gender-based approach to chronic pain. The biochemistry and physiology of the pain pathway, as well as the pharmacokinetics and pharmacodynamics of medications used to remedy pain responses, are signifcantly different between men and women. Low-estradiol states result in a reduction in both mu-opioid receptor recruitment and basal activation, leading to significant hyperalgesia and sensitivity to chronic pain in women as compared to men. Further compounding the dichotomy between the chronic pain response is the response to analgesics. Women have lower levels of glucuronidation, higher volumes of distribution, and lower clearance of commonly administered analgesics as compared to men. Psychosocial factors such as gender roles, expectations surrounding pain, and coping strategies also determine how pain is perceived and ultimately influence how pain is treated. These findings are just beginning to shed light on the ways in which women and men respond differently in vivo to pain. However, the decision to treat women and men as separate entities with respect to pain management should not be a binary one. While patients should be treated as individuals, pre-menopausal, post-menopausal and transgender women, should all be met with an approach that takes into account the sex and gender differences that exist. Pain management physicians should take heed of these complex differences and utilize a sex and gender-based approach while managing patients.https://jdc.jefferson.edu/sexandgenderhealth/1025/thumbnail.jp

Evidence for strong lattice effects as revealed from huge unconventional oxygen isotope effects on the pseudogap temperature in La2−x_{2-x}Srx_{x}CuO4_{4}

The oxygen isotope ($^{16}$O/$^{18}$O) effect (OIE) on the pseudogap (charge-stripe ordering) temperature $T^{\ast}$ is investigated for the cuprate superconductor La$_{2-x}$Sr$_{x}$CuO$_{4}$ as a function of doping $x$ by means of x-ray absorption near edge structure (XANES) studies. A strong $x$ dependent and sign reversed OIE on $T^{\ast}$ is observed. The OIE exponent $\alpha_{T^{\ast}}$ systematically decreases from $\alpha_{T^{\ast}} = - 0.6(1.3)$ for $x = 0.15$ to $\alpha_{T^{\ast}} = - 4.4(1.1)$ for $x = 0.06$, corresponding to increasing $T^{\ast}$ and decreasing superconducting transition temperature $T_{c}$. Both $T^{\ast}(^{16}{\rm O})$ and $T^{\ast}(^{18}{\rm O})$ exhibit a linear doping dependence with different slopes and critical end points (where $T^{\ast}(^{16}{\rm O})$ and $T^{\ast}(^{18}{\rm O})$ fall to zero) at $x_{c}(^{16}{\rm O}) = 0.201(4)$ and $x_{c}(^{18}{\rm O}) = 0.182(3)$, indicating a large positive OIE of $x_{c}$ with an exponent of $\alpha_{x_{c}} = 0.84(22)$. The remarkably large and strongly doping dependent OIE on $T^{\ast}$ signals a substantial involvement of the lattice in the formation of the pseudogap, consistent with a polaronic approach to cuprate superconductivity and the vibronic character of its ground state