A Lesson in Scaling 6LoWPAN -- Minimal Fragment Forwarding in Lossy Networks

This paper evaluates two forwarding strategies for fragmented datagrams in the IoT: hop-wise reassembly and a minimal approach to directly forward fragments. Minimal fragment forwarding is challenged by the lack of forwarding information at subsequent fragments in 6LoWPAN and thus requires additional data at nodes. We compared the two approaches in extensive experiments evaluating reliability, end-to-end latency, and memory consumption. In contrast to previous work and due to our alternate setup, we obtained different results and conclusions. Our findings indicate that direct fragment forwarding should be deployed only with care, since higher packet transmission rates on the link-layer can significantly reduce its reliability, which in turn can even further reduce end-to-end latency because of highly increased link-layer retransmissions.Comment: If you cite this paper, please use the LCN reference: M. S. Lenders, T. C. Schmidt, M. W\"ahlisch. "A Lesson in Scaling 6LoWPAN - Minimal Fragment Forwarding in Lossy Networks." in Proc. of IEEE LCN, 201

Securing name resolution in the IoT: DNS over CoAP

In this paper, we present the design, implementation, and analysis of DNS over CoAP (DoC), a new proposal for secure and privacy-friendly name resolution of constrained IoT devices. We implement different design choices of DoC in RIOT, an open-source operating system for the IoT, evaluate performance measures in a testbed, compare with DNS over UDP and DNS over DTLS, and validate our protocol design based on empirical DNS IoT data. Our findings indicate that plain DoC is on par with common DNS solutions for the constrained IoT but significantly outperforms when additional, CoAP standard features are used such as block-wise transfer or caching. With OSCORE for end-to-end security, we can save more than 10 kBytes of code memory compared to DTLS while enabling group communication without compromising the trust chain when using intermediate proxies or caches. We also discuss a scheme for very restricted links that compresses redundant or excessive information by up to 70%.Comment: 12 pages, 13 figures, 4 table

Landscape change and biodiversity values of floodplains along the River Vistula, Poland.

Item does not contain fulltext20 oktober 200

A 21-Year-Old Pregnant Woman with Hypertension and Proteinuria

Ronald Ma and colleagues describe the differential diagnosis, investigation, and management of a 21-year-old pregnant woman presenting with hypertension and proteinuria at 20 weeks of gestation

A Man with Labile Blood Pressure

Ronald Ma and colleagues discuss the differential diagnosis and management of a patient who presented with recurrent episodes of chest discomfort, palpitations, and labile blood pressure

Pheochromocytoma presenting as recurrent urinary tract infections : a case report

<p>Abstract</p> <p>Introduction</p> <p>Pheochromocytomas are rare, potentially fatal, neuroendocrine tumors of the adrenal medulla or extra-adrenal paraganglia. Their clinical presentation varies greatly from the classic triad of episodic headache, diaphoresis and tachycardia to include a spectrum of non-specific symptomatology.</p> <p>Case presentation</p> <p>A 43-year-old Caucasian woman was referred to us from primary care services with a three-month history of recurrent urinary tract infections on a background of hypertension, latent autoimmune diabetes of adulthood and autoimmune hypothyroidism. At 38 years she required insulin therapy. Despite medication compliance and dietary control, she reported a recent history of increased insulin requirements and uncontrolled hypertension with concomitant recurrent urinary tract infections. A renal ultrasound examination, to rule out underlying renal pathology, revealed an incidental 8cm right adrenal mass of both solid and cystic components. A subsequent computed tomography of her abdomen and pelvis confirmed a solid heterogeneous mass consistent with a pheochromocytoma. There were no other features suggestive of multiple endocrine neoplasia. Urinary collection over 24 hours revealed grossly elevated levels of catecholamines and metabolites. Following an open right adrenalectomy, our patient's insulin requirements were significantly reduced and her symptoms resolved. Two weeks post-operatively, an iodine-131-metaiodobenzylguanidine scintigraphy was negative for residual tumor and metastatic disease. Urinary catecholamine and metabolite concentrations were within the normal range at a follow-up six months later.</p> <p>Conclusion</p> <p>Pheochromocytoma is a rare catecholamine-producing tumor requiring a high index of suspicion for early diagnosis. Our case report serves to highlight the importance of considering pheochromocytoma as a differential diagnosis in the atypical setting of recurrent urinary tract infections and concomitant autoimmune disease.</p

Brown Adipose Tissue in Humans Is Activated by Elevated Plasma Catecholamines Levels and Is Inversely Related to Central Obesity

BACKGROUND: Recent studies have shown that adult human possess active brown adipose tissue (BAT), which might be important in controlling obesity. It is known that ß-adrenoceptor-UCP1 system regulates BAT in rodent, but its influence in adult humans remains to be shown. The present study is to determine whether BAT activity can be independently stimulated by elevated catecholamines levels in adult human, and whether it is associated with their adiposity. METHODOLOGY/PRINCIPAL FINDINGS: We studied 14 patients with pheochromocytoma and 14 normal subjects who had performed both ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) and plasma total metanephrine (TMN) measurements during 2007-2010. The BAT detection rate and the mean BAT activity were significantly higher in patients with elevated TMN levels (Group A: 6/8 and 6.7±2.1 SUVmean· g/ml) than patients with normal TMN concentrations (Group B: 0/6 and 0.4±0.04 SUVmean· g/ml) and normal subjects (Group C: 0/14 and 0.4±0.03 SUVmean·g/ml). BAT activities were positively correlated with TMN levels (R = 0.83, p<0.0001) and were inversely related to body mass index (R = -0.47, p = 0.010), visceral fat areas (R = -0.39, p = 0.044), visceral/total fat areas (R = -0.52, p = 0.0043) and waist circumferences (R = -0.43, p = 0.019). Robust regression revealed that TMN (R = 0.81, p<0.0001) and waist circumferences (R = -0.009, p = 0.009) were the two independent predictors of BAT activities. CONCLUSIONS/SIGNIFICANCE: Brown adipose tissue activity in adult human can be activated by elevated plasma TMN levels, such as in the case of patients with pheochromocytoma, and is negatively associated with central adiposity