The Complexity of Safety Stock Placement in General-Network Supply Chains

We consider the optimization problem of safety stock placement in a supply chain, as formulated in [1]. We prove that this problem is NP-Hard for supply chains modeled as general acyclic networks. Thus, we do not expect to find a polynomial-time algorithm for safety stock placement for a general-network supply chain.Singapore-MIT Alliance (SMA

Multilinear Wavelets: A Statistical Shape Space for Human Faces

We present a statistical model for $3$D human faces in varying expression, which decomposes the surface of the face using a wavelet transform, and learns many localized, decorrelated multilinear models on the resulting coefficients. Using this model we are able to reconstruct faces from noisy and occluded $3$D face scans, and facial motion sequences. Accurate reconstruction of face shape is important for applications such as tele-presence and gaming. The localized and multi-scale nature of our model allows for recovery of fine-scale detail while retaining robustness to severe noise and occlusion, and is computationally efficient and scalable. We validate these properties experimentally on challenging data in the form of static scans and motion sequences. We show that in comparison to a global multilinear model, our model better preserves fine detail and is computationally faster, while in comparison to a localized PCA model, our model better handles variation in expression, is faster, and allows us to fix identity parameters for a given subject.Comment: 10 pages, 7 figures; accepted to ECCV 201

The porcelain gallbladder – laparoscopic approach

Clinica I Chirurgie, Clinica Universitară „Sf.Spiridon”, Universitatea de Medicină şi Farmacie „Gr.T.Popa”, Iaşi, România, Al XII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova cu participare internațională 23-25 septembrie 2015Introducere: Un timp îndelungat colecistul de porţelan a fost considerat o contraindicaţie relativă către colecistectomia laparoscopică datorită incidenţei înalte a cancerului veziculei biliare. Material şi metode: Dintre 12000 pacienţi supuşi colecistectomiei în Clinica I Chirurgie, Iaşi, 5 (0,04%) pacienţi au avut colecist de porţelan. Toţi bolnavii au fost supuşi examenului ultrasonografic. Pacienţii cu colecist de porţelan au fost clasificaţi ca Tip I şi II în conformitate cu rezultatele analizei ultrasonografice preoperatorii: trei cazuri cu colecist de porţelan de tip I şi două cazuri cu colecist de porţelan de tip II (într-un caz a fost identificat carcinom asociat de veziculă biliară). Rezultate: Noi descriem trei cazuri de colecist de porţelan de tip I (calcificarea completă a peretelui vezicii biliare) tratate prin metoda laparoscopică. Colecistectomia laparoscopică a fost dificilă din cauza adeziunii şi problemelor de tracţiune a veziculei biliare cu pereţii îngroşaţi, însă parcursul postoperator a fost fără particularităţi. Rezultatul histopatologic a pieselor a permis stabilirea diagnosticului de colecist de porţelan de tip I şi lipsa cancerului în peretele calcificat al veziculei biliare. Concluzii: În baza cazurilor prezentate şi revistei literaturii, concluzionăm că în pofida unei rate înalte de conversie, pacienţilor cu colecist de porţelan de tip I ar urma să le fie indicată colecistectomia laparoscopică, utilizînd selecţia preoperatorie în baza rezultatelor ultrasonografiei.Introduction: A long time porcelain gallbladder was considered a relative contraindication to laparoscopic cholecystectomy, because of a high incidence of gallbladder cancer. Material and methods: From 12000 patients underwent cholecystectomy in First Surgical Clinic of Iasi, 5 (0.04%) patients had porcelain gallbladder. All patients underwent ultrasound examen. Patients with porcelain gallbladder were classified as Type I to II according to preoperative ultrasound findings: three cases with porcelain gallbladder type I and two cases with porcelain gallbladder type II (in one case we found associated gallbladder carcinoma). Results: We describe a three cases with porcelain gallbladder type I (complete calcification of gallbladder wall) treated by laparoscopic approach. Laparoscopic cholecystectomy was difficult because of adhesions and problems with grasping the thick gallbladder wall, but the postoperative course was uneventful. The histopathologic result of the specimen established the diagnosis of porcelain gallbladder type I and no cancer in the calcified wall of the gallbladder. Conclusions: We conclude based on cases presented and the literature review, although there is a high conversion rate, that patients with a type I porcelain gallbladder should be considered for laparoscopic cholecystectomy using a preoperative selection based on the ultrasound findings

Constrained von Neumann inequalities

An equivalent formulation of the von Neumann inequality states that the backward shift $S^*$ on $\ell_{2}$ is extremal, in the sense that if $T$ is a Hilbert space contraction, then $\|p(T)\| \leq \|p(S^*)\|$ for each polynomial $p$. We discuss several results of the following type : if $T$ is a Hilbert space contraction satisfying some constraints, then $S^*$ restricted to a suitable invariant subspace is an extremal operator. Several operator radii are used instead of the operator norm. Applications to inequalities of coefficients of rational functions positive on the torus are given.Comment: Preprint versio

Design of a nitrogen-implanted titanium-based superelastic alloy with optimized properties for biomedical applications

International audienceIn this study, a superelastic Ni-free Ti-based biomedical alloy was treated in surface by the implantation of nitrogen ions for the first time. The N-implanted surface was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and secondary ion mass spectroscopy, and the superficial mechanical properties were evaluated by nano-indentation and by ball-on-disk tribological tests. To investigate the biocompatibility, the corrosion resistance of the N-implanted Ti alloy was evaluated in simulated body fluids (SBF) complemented by in-vitro cytocompatibility tests on human fetal osteoblasts. After implantation, surface analysis methods revealed the formation of a titanium-based nitride on the substrate surface. Consequently, an increase in superficial hardness and a significant reduction of friction coefficient were observed compared to the non-implanted sample. Also, a better corrosion resistance and a significant decrease in ion release rates have been obtained. Cell culture experiments indicated that the cytocompatibility of the N-implanted Ti alloy was superior to that of the corresponding non-treated sample. Thus, this new functional N-implanted titanium-based superelastic alloy presents the optimized properties that are required for various medical devices: superelasticity, high superficial mechanical properties, high corrosion resistance and excellent cytocompatibility

Retrosternal goiters

Clinica 1 Chirurgie, Clinica de Endocrinologie, Spitalul „Sf.Spiridon”, UMF ”Gr.T.Popa”, Iaşi, România, Al XII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova cu participare internațională 23-25 septembrie 2015Introducere: Noțiunea de guşă retrosternală sau substernală reprezintă coborîrea a mai mult de 50% de glanda tiroidă în cavitatea toracică. Material şi metode: A fost efectuat un studiu retrospectiv a cazurilor de guşă retrosternală sau substernală din totalul de 2482 pacienți ce au suportat tiroidectomie în Clinica 1 Chirurgie din Iaşi în perioada 2000-2010. Guşa retrosternală a fost depistată la 54 (2,17%) pacienți. Toți bolnavii au fost îndreptați la operație din Clinica de Endocrinologie. Rezultate: Vîrsta medie a pacienților la momentul instalării diagnosticului a constituit 55,3±3,58 ani, majoritatea fiind femei – 83,3%. În manifestările clinice ale guşei retrosternale au dominat fenomenele de compresie. Dereglările funcției glandei tiroide au fost determinate prin teste hormonale efectuate în Clinica de Endocrinologie în 15 (27,7%) cazuri. Diagnoza de guşă retrosternală a fost suspectată în baza examenului clinic şi confirmată imagistic: radiografie toracică, ultrasonografie, computer tomografie. Abordul cervical a fost utilizat cu siguranță, sternotomia fiind necesară doar în 8 (14,8%) cazuri. Morbiditatea postoperatorie a constituit 5,5% (3 cazuri) cu mortalitate nulă. Durata medie de spitalizare a fost 4,3 zile. Noi am comparat datele noastre recente cu raportul privind tratamentul guşei retrosternale şi toracice în Clinica 1 Chirurgie din Iaşi în perioada anilor 1950-1979, publicat în revista „Chirurgia” în 1981. Concluzii: Guşa retrosternală reprezintă o formă specifică de patologie a glandei tiroide cu o incidență scăzută. Diagnosticul şi tratamentul guşei retrosternale implică o abordare multidisciplinară. Medicul endocrinolog are un rol important în diagnosticul şi supravegherea postoperatorie. Deşi intervenția chirurgicală este o metoda curativă de elecție pentru guşa substernală, persistă controverse privind abordul chirurgical şi rata complicațiilor. Abordul cervical poate fi utilizat cu siguranță aproape în toate cazurile, sternotomia fiind efectuată fără ezitare în caz de necesitate.Introduction: The term of retrosternal or substernal goiter means that more than 50% of thyroid gland descends in the thorax. Material and methods: There is a retrospective study on retrosternal and substernal goiter and its pathological features among 2482 patients who underwent thyroidectomy between 2000 and 2010 in the First Surgery Clinic of Iasi. Retrosternal goiter was diagnosed in 54 (2.17%) patients. All patients were referred to surgery from the Clinic of Endocrinology. Results: Mean age at diagnosis was 55.3±3.58 years, and most cases were found in women – 83.3%). The clinical picture of retrosternal goiter was dominated by compressive disorders. Thyroid function abnormalities were identified by hormonal assays performed on Endocrinology Clinic Iasi in 15 (27.7%) cases. The diagnosis of retrosternal goiter was suggested by clinical examination and confirmed by imaging: chest X-ray, ultrasound, CT scan. The cervical approach was safely performed. Only in 8 cases (14.8%), sternotomy was necessary. There was no mortality, and morbidity was 5.5% (3 cases). The length of stay in the hospital was 4.3 days. We compared our recent data with a previous report on retrosternal and thoracic goiter treated in First Surgery Clinic of Iasi during 1950 to 1979 and published in the journal “Chirurgia” in 1981. Conclusions: Retrosternal goiter is a particular form of thyroid surgical pathology presented with reduced incidence. Diagnosis and treatment of retrosternal goiter involve a multidisciplinary team. The endocrinologist has an important role in diagnosis and postoperative follow-up. Surgery is the treatment of choice for substernal goiters, but there are still some controversies on surgical approach, and complication rate. The cervical approach can be safely performed in almost all cases but when required, sternotomy should be performed without hesitation

Color-accurate underwater imaging using perceptual adaptive illumination

Capturing color in water is challenging due to the heavy non-uniform attenuation of light in water across the visible spectrum, which results in dramatic hue shifts toward blue. Yet observing color in water is important for monitoring and surveillance as well as marine biology studies related to species identification, individual and group behavior, and ecosystem health and activity monitoring. Underwater robots are equipped with motor control for large scale transects but they lack sensors that enable capturing color-accurate underwater images. We present a method for color-accurate imaging in water called perceptual adaptive illumination. This method dynamically mixes the illumination of an object in a distance-dependent way using a controllable multi-color light source. The color mix compensates correctly for color loss and results in an image whose color composition is equivalent to rendering the object in air. Experiments were conducted with a color palette in the pool and at three different coral reefs sites, and with an underwater robot collecting image data with the new sensor.United States. Office of Naval Research (Project N000140911051