Biochemical characterization of proopiomelanocortin variants in human and owls

In humans the proopiomelanocortin (POMC) gene is located on the short arm of the chromosome 2 at the 23.3 position and encodes a 39kDa peptide with 241 amino acids. This peptide is the precursor of the proopiomelanocortin prohormone and it is produced in both the anterior and posterior lobes of the pituitary, as well as the arcuate nucleus of the hypothalamus. Maturation of POMC involves glycosylation, acetylation, and selective, sequential and tissue specific processing events mediated by proprotein convertases PC-1/3 and PC-2. Proteolytic cleavage of POMC at 9 different locations produces a variety of hormones, including adrenocorticotrophin (ACTH), α-, β- and γ-melanocyte-stimulating hormones (α-MSH, β-MSH, γ-MSH), corticotrophin-like intermediate peptide (CLIP), β-lipotropin (β-LPH), and β-endorphin (Fig. 1.)

Public Review - A Cooperative Uplink Power Control Scheme for Elastic Data Services in Wireless CDMA Systems

This is a paper that is actually an excellent illustration of how CCR differs from more traditional publications, and also one for which I am glad to have the opportunity to write a public review that hopefully can shed some light on the reasons behind its acceptance. Don’t get me wrong, this is not a paper that I regret seeing in CCR, but this is paper that most likely would not have been accepted in most other publications, including conferences and workshops, at least not in its first submission. The focus of the paper is on resource management on the uplink of a CDMA wireless system, and in particular the combination of an admission control algorithm and a cooperative power control algorithm that maximize a utility function across admitted mobiles while taking QoS requirements into account. The topic is arguably important given the growing presence of CDMA wireless systems and the emergence of new standards such EVDO-1X Rev. A, which offer a range of new options allowing the use of independent transmission policies by mobile devices rather than always subjecting them to tight control from the base station. Understanding, if, when, and how such flexibility can be beneficial or harmful is an interesting and timely research area

Coherent population trapping of a single nuclear spin under ambient conditions

Coherent control of quantum systems has far-reaching implications in quantum engineering. In this context, coherent population trapping (CPT) involving dark resonances has played a prominent role, leading to a wealth of major applications including laser cooling of atoms and molecules, optical magnetometry, light storage and highly precise atomic clocks. Extending CPT methods to individual solid-state quantum systems has been only achieved in cryogenic environments for electron spin impurities and superconducting circuits. Here, we demonstrate efficient CPT of a single nuclear spin in a room temperature solid. To this end, we make use of a three-level system with a $\Lambda$-configuration in the microwave domain, which consists of nuclear spin states addressed through their hyperfine coupling to the electron spin of a single nitrogen-vacancy defect in diamond. Dark state pumping requires a relaxation mechanism which, in atomic systems, is simply provided by spontaneous emission. In this work, the relaxation process is externally controlled through incoherent optical pumping and separated in time from consecutive coherent microwave excitations of the nuclear spin $\Lambda$-system. Such a pumping scheme with controlled relaxation allows us (i) to monitor the sequential accumulation of population into the dark state and (ii) to reach a new regime of CPT dynamics for which periodic arrays of dark resonances can be observed, owing to multiple constructive interferences. This work offers new prospects for quantum state preparation, information storage in hybrid quantum systems and metrology.Comment: 13 pages including supplementary information, links to figures correcte

Acoustic behavior of melon-headed whales varies on a diel cycle.

Many terrestrial and marine species have a diel activity pattern, and their acoustic signaling follows their current behavioral state. Whistles and echolocation clicks on long-term recordings produced by melon-headed whales (Peponocephala electra) at Palmyra Atoll indicated that these signals were used selectively during different phases of the day, strengthening the idea of nighttime foraging and daytime resting with afternoon socializing for this species. Spectral features of their echolocation clicks changed from day to night, shifting the median center frequency up. Additionally, click received levels increased with increasing ambient noise during both day and night. Ambient noise over a wide frequency band was on average higher at night. The diel adjustment of click features might be a reaction to acoustic masking caused by these nighttime sounds. Similar adaptations have been documented for numerous taxa in response to noise. Or it could be, unrelated, an increase in biosonar source levels and with it a shift in center frequency to enhance detection distances during foraging at night. Call modifications in intensity, directionality, frequency, and duration according to echolocation task are well established for bats. This finding indicates that melon-headed whales have flexibility in their acoustic behavior, and they collectively and repeatedly adapt their signals from day- to nighttime circumstances

On Evaluating Loss Performance Deviation: A Simple Tool and Its Practical Applications

The focus of this paper is on developing and evaluating a practical methodology for determining if and when different types of traffic can be safely multiplexed within the same service class. The use of class rather than individual service guarantees offers many advantages in terms of scalability, but raises the concern that not all users within a class see the same performance. Understanding when and why a user will experience performance that differs significantly from that of other users in its class is, therefore, of importance. Our approach relies on an analytical model developed under a number of simplifying assumptions, which we test using several real traffic traces corresponding to different types of users. This testing is carried out primarily by means of simulation, to allow a comprehensive coverage of different configurations. Our findings establish that although the simplistic model does not accurately predict the absolute performance that individual users experience, it is quite successful and robust when it comes to identifying situations that can give rise to substantial performance deviations within a service class. As a result, it provides a simple and practical tool for rapidly characterizing real traffic profiles that can be safely multiplexed

Application-Specific Path Switching: A Case Study for Streaming Video

The focus of this paper is on improving the quality of streaming video transmitted over the Internet. The approach we investigate assumes the availability of multiple paths between the source and the destination, and dynamically selects the best one. Although this is not a new concept, our contribution is in estimating the goodness of a path from the perspective of the video stream, instead of relying only on raw network performance measures. The paper starts by showing that the use of raw network performance data to control path switching decisions can often result in poor choices from an application perspective, and then proceeds to develop a practical approach for evaluating, in real-time, the performance of different paths in terms of video quality. Those estimates are used to continuously select the path that yields the best possible transmission conditions for video streaming applications. We demonstrate the feasibility and performance of the scheme through experiments involving different types of videos

On the Robustness of Router-based Denial-of-Service (DoS) Defense Systems

This paper focuses on router-based defense mechanisms, and whether they can provide effective solutions to network Denial-of-Service (DoS) attacks. Router-based defenses operate either on traffic aggregates or on individual flows, and have been shown, either alone or in combination with other schemes, e.g., traceback, to be reasonably effective against certain types of basic attacks. Those attacks are, however, relatively brute-force, and usually accompanied by either significant increases in congestion, and/or traffic patterns that are easily identified. It is, therefore, unclear if router-based solutions are viable in the presence of more diverse or sophisticated attacks. As a result, even if incorporating defense mechanisms in the routers themselves has obvious advantages, such schemes have not seen wide deployments. Our ultimate goal is to determine whether it is possible to build router-based defense mechanisms that are effective against a wide range of attacks. This paper describes a first phase of this effort aimed at identifying weaknesses in existing systems. In particular, the paper demonstrates that aggregate defense systems can be readily circumvented, even by a single attacker, through minor modifications of its flooding patterns. Flow-based defenses fare slightly better, but can still be easily fooled by a small number of attackers generating transient flooding patterns. The findings of the paper provide insight into possible approaches for designing better and more robust router-based defense systems

Aggregation and Conformance in Differentiated Service Networks: A Case Study

The Differentiated Service (Diff-Serv) architecture [1] advocates a model based on different “granularity” at network edges and within the network. In particular, core routers are only required to act on a few aggregates that are meant to offer a pre-defined set of service levels. The use of aggregation raises a number of questions for end-to-end services, in particular when crossing domain boundaries where policing actions may be applied. This paper focuses on the impact of such policing actions in the context of individual and bulk services built on top of the Expedited Forwarding (EF) [7] per-hop-behavior (PHB). The findings of this investigation confirm and quantify the expected need for reshaping at network boundaries, and identify a number of somewhat unexpected behaviors. Recommendations are also made for when reshaping is not available